space travel and health

Scientists Release Largest Trove of Data on How Space Travel Affects the Human Body

A collection of 44 new studies, largely based on a short-duration tourist trip in 2021, provides insight into the health effects of traveling to space

Will Sullivan

Daily Correspondent

More and more humans are traveling to space. Several missions in 2021 took private citizens on tourist flights. Last month, six people flew to the edge of Earth’s atmosphere and back. NASA plans to put astronauts back on the moon later this decade, and SpaceX recently tested a rocket it hopes will one day carry humans to Mars.

With even more ambitious crewed flights on the horizon, scientists want to better understand the effects that space’s stressors—such as exposure to radiation and a lack of gravity—have on the human body. Now, a newly released set of 44 papers and troves of data, called the Space Omics and Medical Atlas (SOMA), aims to do just that.

SOMA is the largest collection of data on aerospace medicine and space biology ever compiled. It dramatically expands the amount of information available on how the human body changes during spaceflight. And the first studies to come out of this project improve scientists’ understanding of how space travel affects human health.

“This will allow us to be better prepared when we’re sending humans into space for whatever reason,” Allen Liu , mechanical engineer at the University of Michigan who is not involved in the project, tells Adithi Ramakrishnan of the Associated Press (AP).

Much of the new atlas is based on data collected from the four members of the Inspiration4 mission , a space tourism flight that sent four civilians on a three-day trip to low-Earth orbit in September 2021. The findings suggest people on short-term flights experience some of the same health impacts that astronauts face on long-term trips to space.

“We don’t yet fully understand all of the risks” of long-duration space travel, Amy McGuire , a biomedical ethicist at Baylor College of Medicine who did not contribute to the work, says to Science ’s Ramin Skibba. “This is also why it is so important that early space tourists participate in research.”

Space travel poses a number of risks to health. Without Earth’s atmosphere and magnetic field to protect them, astronauts are exposed to space radiation , which can increase their risk for cancer and degenerative diseases. Fluid shifts into astronauts’ heads when they are experiencing weightlessness, which can contribute to vision problems , headaches and changes in the structure of the brain . The microgravity environment can also lead to a loss of bone density and atrophied muscles , prompting long-haul astronauts to adopt specific exercise regimens .

But on top of those known risks, the new research highlights other potential issues. One study published Tuesday in the journal Nature Communications found that mice exposed to a dose of radiation meant to simulate a round trip to Mars experienced kidney damage and dysfunction. Human travelers might need to be on dialysis on the way back from the Red Planet if they were not protected from this radiation, writes the Guardian ’s Ian Sample.

“It’s likely to be a serious issue,” Stephen Walsh , a co-author of the study and clinician scientist at University College London, tells the publication. “It’s very hard to see how that’s going to be okay.”

The health information from the Inspiration4 astronauts sheds light on how space travel can affect private citizens who have not extensively trained for it. The findings also highlight changes to cells and DNA that can occur during short trips to space.

Biomarkers that changed during the Inspiration4 mission returned to normal a few months after the trip, suggesting that space travel doesn’t pose a greater risk to civilians than it does for trained astronauts, Christopher Mason , a geneticist at Cornell University who helped put together the atlas, says to New Scientist ’s Clare Wilson.

The Inspiration4 research also suggests women may recover faster from space travel than men. Data from the mission’s two male and two female participants, along with data from 64 NASA astronauts, indicated that gene activity related to the immune system was more disrupted in male astronauts, per the Guardian . And men’s immune systems took longer to return to normal once back on Earth.

Taken together, the new papers could help researchers learn how to ameliorate the harms space travel can cause, Afshin Beheshti , a co-author of the work and a researcher with the Blue Marble Space Institute of Science, says to the AP.

And the scientists say nothing in the data suggests humans should not go to space.

“There’s no showstopper,” Mason tells the Washington Post ’s Joel Achenbach. “There’s no reason we shouldn’t be able to safely get to Mars and back.”

Get the latest stories in your inbox every weekday.

Will Sullivan | | READ MORE

Will Sullivan is a science writer based in Washington, D.C. His work has appeared in Inside Science and NOVA Next .

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

• Publications
• Account settings

Preview improvements coming to the PMC website in October 2024. Learn More or Try it out now .

• Advanced Search
• Journal List

Human Health during Space Travel: State-of-the-Art Review

Chayakrit krittanawong.

1 Department of Medicine and Center for Space Medicine, Section of Cardiology, Baylor College of Medicine, Houston, TX 77030, USA

2 Translational Research Institute for Space Health, Houston, TX 77030, USA

3 Department of Cardiovascular Diseases, New York University School of Medicine, New York, NY 10016, USA

Nitin Kumar Singh

4 Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA

Richard A. Scheuring

5 Flight Medicine, NASA Johnson Space Center, Houston, TX 77058, USA

Emmanuel Urquieta

6 Department of Emergency Medicine and Center for Space Medicine, Baylor College of Medicine, Houston, TX 77030, USA

Eric M. Bershad

7 Department of Neurology, Center for Space Medicine, Baylor College of Medicine, Houston, TX 77030, USA

Timothy R. Macaulay

8 KBR, Houston, TX 77002, USA

Scott Kaplin

9 Department of Dermatology, Baylor College of Medicine, Houston, TX 77030, USA

Stephen F. Kry

10 Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA

Thais Russomano

11 InnovaSpace, London SE28 0LZ, UK

Marc Shepanek

12 Office of the Chief Health and Medical Officer, NASA, Washington, DC 20546, USA

Raymond P. Stowe

13 Microgen Laboratories, La Marque, TX 77568, USA

Andrew W. Kirkpatrick

14 Department of Surgery and Critical Care Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada

Timothy J. Broderick

15 Florida Institute for Human and Machine Cognition, Pensacola, FL 32502, USA

Jean D. Sibonga

16 Division of Biomedical Research and Environmental Sciences, NASA Lyndon B. Johnson Space Center, Houston, TX 77058, USA

Andrew G. Lee

17 Department of Ophthalmology, University of Texas Medical Branch School of Medicine, Galveston, TX 77555, USA

18 Department of Ophthalmology, Blanton Eye Institute, Houston Methodist Hospital, Houston, TX 77030, USA

19 Department of Ophthalmology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA

20 Department of Ophthalmology, Texas A and M College of Medicine, College Station, TX 77807, USA

21 Department of Ophthalmology, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA

22 Departments of Ophthalmology, Neurology, and Neurosurgery, Weill Cornell Medicine, New York, NY 10021, USA

Brian E. Crucian

23 National Aeronautics and Space Administration (NASA) Johnson Space Center, Human Health and Performance Directorate, Houston, TX 77058, USA

Associated Data

The field of human space travel is in the midst of a dramatic revolution. Upcoming missions are looking to push the boundaries of space travel, with plans to travel for longer distances and durations than ever before. Both the National Aeronautics and Space Administration (NASA) and several commercial space companies (e.g., Blue Origin, SpaceX, Virgin Galactic) have already started the process of preparing for long-distance, long-duration space exploration and currently plan to explore inner solar planets (e.g., Mars) by the 2030s. With the emergence of space tourism, space travel has materialized as a potential new, exciting frontier of business, hospitality, medicine, and technology in the coming years. However, current evidence regarding human health in space is very limited, particularly pertaining to short-term and long-term space travel. This review synthesizes developments across the continuum of space health including prior studies and unpublished data from NASA related to each individual organ system, and medical screening prior to space travel. We categorized the extraterrestrial environment into exogenous (e.g., space radiation and microgravity) and endogenous processes (e.g., alteration of humans’ natural circadian rhythm and mental health due to confinement, isolation, immobilization, and lack of social interaction) and their various effects on human health. The aim of this review is to explore the potential health challenges associated with space travel and how they may be overcome in order to enable new paradigms for space health, as well as the use of emerging Artificial Intelligence based (AI) technology to propel future space health research.

1. Introduction

Until now space missions have generally been either of short distance (Low Earth Orbit—LEO) or short duration (Apollo Lunar Missions). However, upcoming missions are looking to push the boundaries of space travel, with plans to travel for longer distances and durations than ever before. Both the National Aeronautics and Space Administration (NASA) and several commercial space companies (e.g., Blue Origin, SpaceX) have already started the process of preparing for long distance, long-duration space exploration and currently plan to explore inner solar planets (e.g., Mars) by the 2030s [ 1 ].

Within the extraterrestrial environment, a multitude of exogenous and endogenous processes could potentially impact human health in several ways. Examples of exogenous processes include exposure to space radiation and microgravity while in orbit. Space radiation poses a risk to human health via a number of potential mechanisms (e.g., alterations of gut microbiome biosynthesis, accelerated atherosclerosis, bone remodeling, and hematopoietic effects) and prolonged microgravity exposure presents additional potential health risks (e.g., viral reactivation, space motion sickness, muscle/bone atrophy, and orthostatic intolerance) [ 2 , 3 , 4 , 5 , 6 , 7 ]. Examples of endogenous processes potentially impacted by space travel include alteration of humans’ natural circadian rhythm (e.g., sleep disturbances) and mental health disturbances (e.g., depression, anxiety) due to confinement, isolation, immobilization, and lack of social interaction [ 8 , 9 , 10 ]. Finally, the risk of unknown exposures, such as yet undiscovered pathogens, remain persistent threats to consider. Thus, prior to the emergence of long distance, long duration space travel it is critical to anticipate the impact of these varied environmental factors and identify potential mitigating strategies. Here, we review the available medical literature on human experiments conducted during space travel and summarize our current knowledge on the effects of living in space for both short and long durations of time. We also discuss the potential countermeasures currently employed during interstellar travel, as well as future directions for medical research in space.

1.1. Medical Screening and Certification Prior to Space Travel

When considering preflight medical screening and certification, the requirements and recommendations vary based on the duration of space travel. Suborbital spaceflight, part of the new era of space travel, has participants launching to the edge of space (defined as the Karman line, 100 Km above mean sea level) for brief 3–5 min microgravity exposures. Orbital spaceflight, defined as microgravity exposure for up to 30 days, involves healthy individuals with preflight medical screening. In addition to a physical examination and metabolic screening, preflight medical screening assessing aerobic capacity (VO 2max ), and muscle strength and function may be sufficient to ensure proper conditioning prior to mission launch [ 11 , 12 , 13 , 14 ]. Age-appropriate health screening tests (e.g., colonoscopy, serum prostate specific antigen in men, and mammography in women) are generally recommended for astronauts in the same fashion as their counterparts on Earth. In individuals with cardiovascular risk factors or with specific medical conditions, additional screening may be required [ 15 ]. The goal of these preflight screening measures is to ensure that medical conditions that may result in sudden incapacitation are identified and either disqualified or treated before the mission begins. In addition to the medical screening described above, short-duration space travelers are also required to undergo acceleration training, hypobaric and hypoxia exposure training, and hypercapnia awareness procedures as part of the preflight training phase.

In preparation for long-duration space travel, astronauts generally undergo a general physical examination, as well as imaging and laboratory studies at the time of initial selection. These screening tests would then be repeated annually, as well as upon assignment to an International Space Station (ISS) mission. ISS crew members are medically certified for long-duration spaceflight missions through individual agency medical boards (e.g., NASA Aerospace Medical Board) and international medical review boards (e.g., Multilateral Space Medicine Board) [ 16 , 17 ]. In order for an individual to become certified for long-duration space travel, an individual must be at the lowest possible risk for the occurrence of medical events during the preflight, infight, and postflight periods. Following spaceflight, it is recommended that returning astronauts undergo occupational surveillance for the remainder of their lifetime for the detection of health issues related to space travel (e.g., NASA’s Lifetime Surveillance of Astronaut Health program) [ 18 ]. Table 1 summarizes the preflight, inflight, and postflight screening recommendations for each organ system. Further research utilizing data from either long-term space missions or simulated environments is required in order to develop an adequate preflight scoring system capable of predicting inflight and postflight health outcomes in space travelers based on various risk factors.

Summarizes the pre-flight, in-flight and post-flight screening in each system.

Below we discuss potential Space Hazards for each organ system along with possible countermeasures ( Table 2 ). Table 3 lists prospective opportunities for artificial intelligence (AI) implementation.

Summary of Space Hazards to each organ system and potential countermeasures.

Potential AI applications in space health.

1.2. Effects on the Cardiovascular System

During short-duration spaceflight, microgravity alters cardiovascular physiology by reducing circulatory blood volume, diastolic blood pressure, left ventricular mass, and cardiac contractility [ 42 , 123 ]. Several studies have demonstrated that peak exercise performance is reduced both inflight and immediately after short-duration spaceflight due primarily to a reduction in maximal cardiac output and O 2 delivery [ 124 , 125 ]. Prolonged exposure to microgravity does cause unloading of the cardiovascular system (e.g., removal of expected loading effects from Earth’s gravity when upright during the day), resulting in cardiac atrophy. These changes may be an example of adaptive physiologic changes (“physiologic atrophy”) that returns to baseline after returning from spaceflight. This process may be similar to the adaptive physiologic changes to the cardiovascular system seen during athletic training (“physiologic hypertrophy”). Thus far, there is no evidence that the observed short-term cardiac atrophy could permanently impair systolic function. However, this physiologic adaptation to microgravity in space could lead to orthostatic hypotension/intolerance upon returning to Earth’s gravity due to changes in the comparative position of peripheral resistance and sympathetic nerve activity [ 41 , 126 , 127 ]. Figure 1 demonstrates potential effects of the space environment on each organ system.

Potential effects of the space environment on each organ system.

Another potential effect of microgravity exposure is that an alteration of hydrostatic forces in the vertical gravitational (Gz) axis could lead to the formation of internal jugular vein thromboses [ 28 , 29 ]. Anticoagulation would not be an ideal choice for prevention as astronauts have an increased risk of suffering traumatic injury during spaceflight, thus potentially inflating the risk of developing an intracerebral hemorrhage or subdural hematoma. In addition, if a traumatic accident were to occur during spaceflight, the previously discussed cardiovascular adaptations could impair the body’s ability to tolerate blood loss and shock [ 45 , 46 , 47 ].

During long-duration spaceflight, one recent study demonstrated that astronauts did not experience orthostatic hypotension/intolerance during routine activities or after landing following 6 months in space [ 128 ]. It is worth noting that all of these astronauts performed aggressive exercise countermeasures while in flight [ 128 ]. Another study of healthy astronauts after 6 months of space travel showed that the space environment caused transient changes in left atrial structure/electrophysiology, increasing the risk of developing atrial fibrillation (AF) [ 129 ]. However, there was no definitive evidence of increased incidence of supraventricular arrhythmias and no identified episodes of AF [ 129 ]. Evaluation with echocardiography or cardiac MRI may be considered following long-duration spaceflight in certain cases.

Prior human studies with supplemental data obtained from animal studies, have shown that healthy individuals with prolonged exposure to ionizing radiation may be at increased risk for the development of accelerated atherosclerosis secondary to radiation-induced endothelial damage and a subsequent pro-inflammatory response [ 3 , 4 , 57 , 58 , 59 , 60 , 123 ]. One study utilizing human 3D micro-vessel models showed that ionizing radiation inhibits angiogenesis via mechanisms dependent on the linear energy transfer (LET) of charged particles [ 130 ], which could eventually lead to cardiac dysfunction [ 131 , 132 ]. In fact, specific characteristics of the radiation encountered in space may be an important factor to understanding its effects. For example, studies of pediatric patients undergoing radiotherapy have shown an increase in cardiac-related morbidity/mortality due to radiation exposure, but not until radiation doses exceeded 10 Gy [ 133 ]. At lower dose levels the risk is less clear: while a study of atomic bomb survivors with more than 50 years of followup demonstrated elevated cardiovascular risks at doses < 2 Gy [ 134 ]. A recent randomized clinical trial with a 20-year follow-up showed no increase in cardiac mortality in irradiated breast cancer patients with a median dose of 3.0 Gy (1.1–8.1 Gy) [ 135 ]. The uncertainty in cardiovascular effects of ionizing radiation, are accentuated in a space environment as the type and quality of radiation likely play an important role as well.

Further research is required to understand the radiation dosage, duration, and quality necessary for cardiovascular effects to manifest, as well as develop preventive strategies for AF and internal jugular vein thrombosis during space travel.

1.3. Effects on the Gastrointestinal System

During short-duration spaceflight, the presence of gastrointestinal symptoms (e.g., diarrhea, vomiting, and inflammation of the gastrointestinal tract) are common due to microgravity exposure [ 35 , 136 , 137 ]. Still unknown however is whether acute, surgical conditions such as cholecystitis and appendicitis occur more frequently due to microgravity-induced stone formation or alterations in human physiology/anatomy, and immunosuppression [ 40 ]. Controlling for traditional risk factors associated with the development of these conditions (e.g., adequate hydration, maintenance of a normal BMI, dietary fat avoidance, etc.) may help mitigate the risk.

During long-duration spaceflight, it is possible that prolonged radiation exposure could lead to radiation-induced gastrointestinal cancer. Gamma radiation exposure is a known risk factor for colorectal cancer via an absence of DNA methylation [ 138 ]. NASA has recently developed a space radiation simulator, named the “GCR Simulator”, which allows for the more accurate radiobiologic research into the development and mitigation of radiation-induced malignancies [ 139 ]. Preflight colorectal cancer screening via colonoscopy or inflight screening via gut microbiome monitoring may be beneficial, but further research is required to demonstrate their clinical utility. Several studies, including the NASA Twins study have shown that microgravity could lead to alterations in an individual’s gut microbial community (i.e., gut dysbiosis) [ 2 , 140 , 141 , 142 ]. While changes to an individual’s gut microbiome can cause inflammation of the gastrointestinal tract [ 143 , 144 ], it remains unclear whether the specific alterations observed during spaceflight pose a risk to astronaut health. In fact, increased gut colonization by certain bacterial species is even associated with a beneficial effect on the gastrointestinal tract [ 2 , 140 ]. ( Table S1 ) Certain limitations of these studies, such as variations in genomic profile, diet, and a lack of adjusted confounders (e.g., the microbial content of samples) should be considered. Another potential consequence of prolonged microgravity exposure is the possibility of increased fatty-acid processing [ 145 ], leading to the development of non-alcoholic fatty liver disease (NAFLD) and hepatic fibrosis [ 146 , 147 ].

Further research is required to better understand gut microbial dynamics during space travel, as well as spaceflight-associated risk factors for the development of NAFLD, cholecystitis, and appendicitis.

1.4. Effects on the Immune System

During spaceflight, exposure to microgravity could potentially induce modifications in the cellular function of the human immune system. For example, it has been hypothesized that microgravity exposure could lead to an increase in the production of inflammatory cytokines [ 148 ] and stress hormones [ 149 , 150 ], alterations in the function of certain cell lines (NK cells [ 151 , 152 ], B cells [ 153 ], monocytes [ 154 ], neutrophils [ 154 ], T cells [ 5 , 155 ]), and impairments of leukocyte distribution [ 156 ] and proliferation [ 155 , 157 , 158 ]. The resultant immune system dysfunction could lead to the reactivation of latent viruses such as Epstein-Bar Virus (EBV), Varicella-Zoster Virus (VZV), and Cytomegalovirus (CMV) [ 31 , 32 ]. Persistent low-grade pro-inflammatory responses microgravity could lead to space fever. [ 159 ] Studies are currently underway to evaluate countermeasures to improve immune function and reduce reactivation of latent herpesviruses [ 33 , 160 , 161 , 162 ]. Microgravity exposure could also lead to the development of autoantibodies, predisposing astronauts to various autoimmune conditions [ 136 , 163 ]. ( Table S2 ) Most importantly, studies have shown that bacteria encountered within the space environment appear to be more resistant to antibiotics and more harmful in general compared to bacteria encountered on Earth [ 164 , 165 ]. This is in addition to the threat of novel bacteria species (e.g., Methylobacterium ajmalii sp. Nov. [ 76 ]) that we have not yet discovered.

Upon returning from the space environment astronauts remain in an immunocompromised state, which has been particularly problematic in the era of the COVID-19 pandemic. Recently, NASA has recommended postflight quarantine and immune status monitoring (i.e., immune-boosting protocol) to mitigate the risk of infection [ 77 ]. This is similar to the Apollo and NASA Health Stabilization Programs that helped establish the preflight protocol (pre-mission quarantine) currently used for this purpose.

Further research is required to understand the mechanisms of antibiotic resistance and the modifications in inflammatory cytokine dynamics, in order to develop immune boosters and surrogate immune biomarkers.

1.5. Effects on the Hematologic System

During short-duration spaceflight, the plasma volume and total blood volume de-crease within the first hours and remain reduced throughout the inflight period, a finding previously identified as space anemia [ 166 ]. Space anemia during spaceflight is perhaps due to a normal physiologic adaptation of newly released blood cells and iron metabolism to microgravity [ 167 ].

During long-duration spaceflight, microgravity exposure could potentially induce hemoglobin degradation, leading to hemolytic anemia. In a recent study of 14 astronauts who were on 6-month missions onboard the ISS, a 54% increase in hemolysis was ob-served after landing one year later [ 50 ]. In another small study, nearly half of astronauts (48%) landing after long duration missions were anemic and hemoglobin levels were characterized as having a dose–response relationship with microgravity exposure [ 51 ]. An additional study collected whole blood sample from astronauts during and after up to 6 months of orbital spaceflight [ 168 ]. Upon analysis, once the astronauts returned to Earth RBC and hemoglobin levels were significantly elevated. It is worth noting that these studies analyzed blood samples from astronauts collected after spaceflight, which may be influenced by various factors (e.g., the stress of landing and re-adaptation to conditions on Earth). In addition, these studies may be confounded by other extraterrestrial environmental factors such as fluid shifts, dehydration, and alteration of the circadian cycle.

Further research is urgently needed to understand plasma volume physiology dur-ing spaceflight and delineate the etiology and degree of hemolysis with longer space exposure, such as 1-year ISS or Mars exploration missions.

1.6. Oncologic Effects

Even during short-duration spaceflight, the stochastic nature of cancer development makes it possible that space radiation exposure could cause cancer via epigenomic modifications [ 63 ]. Currently, our epidemiological understanding of radiation-induced cancer risk is based primarily on atomic bomb survivors and accidental radiation exposures, which both show a clear association between radiation exposure and cancer risk [ 169 , 170 ]. However, these studies are hard to generalize to spaceflight as the patient populations vary significantly (generally healthy astronauts vs. atomic bomb survivors [NCRP 126]) [ 171 ]. Moreover, the radiation encountered in space is notably different than that associated with atomic bomb exposure. Most terrestrial exposures are based on low LET radiation (e.g., atomic bomb survivors received <1% dose from high LET neutrons) [ 172 ], whereas space radiation is comprised of higher LET ions (solar energetic particles and galactic cosmic rays) [ 173 , 174 ].

During long-duration spaceflight, our current understanding of cancer risk is also largely unknown. Our current epidemiologic understanding of long-duration radiation exposure and cancer risk is primarily based on the study of chronic occupational exposures and medically exposed individuals, supplemented with data obtained from animal studies, which are again based overwhelmingly on low LET radiation [ 169 , 170 , 175 , 176 ]. In animal studies, exposure to ionizing radiation (up to 13.5 months) has been associated with an increased risk of developing a variety of cancers [ 162 , 177 , 178 , 179 , 180 ]. Ionizing radiation exposure may cause DNA methylation patterns similar to the specific patterns observed in human adenocarcinomas and squamous cell carcinomas [ 63 ]; however, this response is not yet certain [ 181 , 182 ].

For the purposes of risk prediction, the elevated biological potency of heavy ions is modeled through concepts such as the radiation weighting factor, with NASA recently releasing unique quality factors ( Q NASA ) focused on high density tracks [ 183 ]. Although these predictive models can only estimate the impact of radiation exposure, extrapolation of current terrestrial-based data suggest that this risk could be at least substantial for astronauts. NASA, for example, has updated crew permissible career exposure limits to 0.6Sv, independent of age and sex. This degree of exposure results in a 2–3% mean increased risk of death from radiation carcinogenesis (NCRP 2021) [ 184 ]. This limit would be reached between 200 and 400 days of space travel (depending on degree of radiation shielding) [ 48 ].

Further research is urgently needed to understand the true risk of space radiation exposure. This is especially important for individuals with certain genotype-phenotype profiles (e.g., BRCA1 or DNA methylation signatures) who may be more sensitive to the effects of radiation exposure. Most importantly, the utilization of genotype-phenotype profiles of astronauts or space travelers is valuable not just for pre-flight screening, but also during in-flight travel, especially for long-duration flights to deeper space. An individual’s genetic makeup will in-variably change during spaceflight due to the shifting epigenetic microenvironment. Future crewed-missions to deep space will have to adapt to these anticipated changes, be-come aware of impending red-flag situations, and determine whether any meaningful shift or change to ones’ genetic makeup is possible. For example, personalized radiation shields could potentially be tailored to an individuals’ genotype-phenotype profile, individualized pulmonary capillary wedge pressure under microgravity may be different due to transient changes in left atrial structure, or preflight analysis of the globin gene for the prediction of space anemia [ 50 , 129 , 185 ]. This research should be designed to identify the radiation type, dose, quality, frequency, and duration of exposure required for cancer development.

1.7. Effects on the Neurologic System

During the initial days of spaceflight, space motion sickness (SMS) is the most commonly encountered neurologic condition. Microgravity exposure during spaceflight commonly leads to alterations in spatial orientation and gaze stabilization (e.g., shape recognition [ 186 ], depth perception and distance [ 187 , 188 ]). Postflight, impairments in object localization during pitch and roll head movements [ 189 , 190 ] and fine motor control (e.g., force modulation [ 191 ], keyed pegboard completion time [ 192 ], and bimanual coordination [ 193 ]) are common. Anecdotally, astronauts also reported alterations in smell and taste sensations during their missions [ 27 , 194 , 195 ]. The observed impairment in olfactory function is perhaps due to elevated intracranial pressure (ICP) with increased cerebrospinal fluid outflow along the cribriform plate pathways [ 196 ]. However, to date, there have been no studies directly measuring ICP during spaceflight.

Upon returning from spaceflight, studies have observed that astronauts experience decrements in postural and locomotor control that can increase fall risk [ 197 ]. These decrements have been observed in both standard sensorimotor testing and functional tasks. While recovery of sensorimotor function occurs rapidly following short-duration spaceflight (within the first several days after return) [ 192 , 198 ], recovery after long-duration spaceflight often takes several weeks. Similar to SMS, post-flight motion sickness (PFMS) is very common and occurs soon after g-transition [ 30 ]. Deficits in dexterity, dual-tasking, and vehicle operation [ 199 ] are also commonly observed immediately after spaceflight. Therefore, short-duration astronauts are recommended to not drive automobiles for several days, and only after a sensorimotor evaluation (similar to a field sobriety test).

Similarly to the effects seen following short-duration spaceflight, those returning from long-duration spaceflight can also experience deficits in dexterity, dual-tasking, and vehicle operation. Long-duration astronauts are recommended to not drive automobiles for several weeks, and also require a sensorimotor evaluation. While central nervous system (CNS) changes [ 53 ] associated with long-duration spaceflight are commonly observed, the resulting effects of these changes both during and immediately after spaceflight remain unclear [ 199 ]. Observed CNS changes include structural and functional alterations (e.g., upward shift of the brain within the skull [ 54 ], disrupted white matter structural connectivity [ 55 ], increased fluid volumes [ 56 ], and increased cerebral vasoconstriction [ 200 ]), as well as modifications to adaptive plasticity [ 53 ]. Adaptive reorganization is primarily observed in the sensory systems. For example, changes in functional connectivity during plantar stimulation have been observed within sensorimotor, visual, somatosensory, and vestibular networks after spaceflight [ 201 ]. In addition, functional responses to vestibular stimulation were altered after spaceflight―reducing the typical deactivation of somatosensory and visual cortices [ 202 ]. These studies provide evidence for sensory reweighting among visual, vestibular, and somatosensory inputs.

Further research is required to fully understand the observed CNS changes. In addition, integrated countermeasures are needed for the acute effects of g-transitions on sensorimotor and vestibular function.

1.7.1. Effects on the Neuro-Ocular System

Prolonged exposure to ionizing radiation is well known to produce secondary cataracts [ 61 , 62 ]. Most importantly, Spaceflight Associated Neuro-Ocular Syndrome (SANS) is a unique constellation of clinical and imaging findings which occur to astronauts both during and after spaceflight, and is characterized by: hyperopic refractive changes (axial hyperopia), optic disc edema, posterior globe flattening, choroidal folds, and cotton wool spots [ 43 ]. Ophthalmologic screening for SANS, including both clinical and imaging assessments is recommended. ( Figure 2 ) Although the precise etiology and mechanism for SANS remain ill-defined, some proposed risk factors for the development of SANS include microgravity related cephalad fluid shifts [ 203 ], rigorous resistive exercise [ 204 ], increased body weight [ 205 ], and disturbances to one carbon metabolic pathways [ 206 ]. Many scientists believe that the cephalad fluid shift secondary to microgravity exposure is the major pathophysiological driver of SANS [ 203 ]. Although inflight lumbar puncture has not been attempted, several mildly elevated ICPs have been recorded in astronauts with SANS manifestations upon returning to Earth [ 43 ]. Moreover, changes to the pressure gradient between the intraocular pressure (IOP) and ICP (the translaminar gradient) have been proposed as a pathogenic mechanism for SANS [ 207 ]. The translaminar gradient may explain the structural changes seen in the posterior globe such as globe flattening and choroidal folds [ 207 ]. Alternatively, the microgravity induced cephalad fluid shift may impair venous or cerebrospinal drainage from the cranial cavity and/or the eye/orbit (e.g., choroid or optic nerve sheath). Impairment of the glymphatic system has also been proposed as a contributing mechanism to SANS, but this remains unproven [ 208 , 209 ]. Although permanent visual loss has not been observed in astronauts with SANS, some structural changes (e.g., posterior globe flattening) may persist and have been documented to remain for up to 7 years of long-term follow-up [ 210 ]. Further research is required to better understand the mechanism of SANS, and to develop effective countermeasures prior to longer duration space missions.

Ophthalmologic screening for SANS.

1.7.2. Effects on the Neuro-Behavioral System

The combination of mission-associated stressors with the underlying confinement and social isolation of space travel has the potential to lead to cognitive deficits and the development of psychiatric disorders [ 211 ]. Examples of previously identified cognitive deficits associated with spaceflight include impaired concentration, short-term memory loss, and an inability to multi-task. These findings are most evident during G-transitions, and are likely due to interactions between vestibular and cognitive function [ 212 , 213 ]. Sopite syndrome, a neurologic component of motion sickness, may account for some cognitive slowing. The term “space fog”, has been used to describe the generalized lack of focus, altered perception of time, and cognitive impairments associated with spaceflight, which can occur throughout the mission. This may be related to chronic sleep deprivation as deficiencies (including decreased sleep duration and quality of sleep) are prevalent despite the frequent use of sleep medications [ 71 ]. These results highlight the broad impact of space travel on cognitive and behavioral health, and support the need for integrated countermeasures for long-duration explorative missions.

1.8. Effects on the Musculoskeletal System

During short-duration spaceflight, low back pain and disk herniation are common due to the presence of microgravity. While the pathogenesis of space-related low back pain and disk herniation is complex, the etiology is likely multifactorial in nature (e.g., microgravity induced hydration and swelling of the vertebral disk, muscle atrophy of the neck and lower back) [ 19 , 214 , 215 ]. Additionally, various joint injuries (e.g., space-suited shoulder injuries) can also occur in space due to the presence of microgravity [ 16 , 216 , 217 , 218 ]. Interestingly, one study showed that performing specific exercises could potentially promote automatic and tonic activation of lumbar multifidus and transversus abdominis as well as prevent normal lumbopelvic positioning against gravity following bed rest as a simulation of space flight [ 219 ], and the European Space Agency suggested that exercise program could relieve low back pain during spaceflight [ 220 ]. Further longitudinal studies are required to develop specialized exercise protocols during space travel.

During long-duration spaceflight, the presence of microgravity could cause an alteration in collagen fiber orientation within tendons, reduce articular cartilage and meniscal glycosaminoglycan content, and impair the wound healing process [ 22 , 23 , 24 , 221 ]. These findings seen in animal studies suggest that mechanical loading is required in order for these processes to occur in a physiologic manner. It is theorized that there is a mandatory threshold of skeletal loading necessary to direct balanced bone formation and resorption during healthy bone remodeling [ 222 , 223 ]. Despite the current countermeasure programs, the issue of skeletal integrity is still not solved [ 224 , 225 , 226 ].

Space radiation could also impact bone remodeling, though the net effect differs based on the amount of radiation involved [ 6 ]. In summary, high doses of space radiation lead to bone destruction with increased bone resorption and reduced bone formation, while low doses of space radiation actually have a positive impact with increased mineralization and reduced bone resorption. Most importantly, space radiation, particularly solar particle events in the case of a flare, may induce acute radiation effects, leading to hematopoietic syndrome [ 7 ]. This risk is highest for longer duration missions, but can be substantially minimized with current spacecraft shielding options.

Longitudinal studies are required to develop special exercise protocols and further assess the aforementioned risk of space radiation on the development of musculoskeletal malignancies.

1.9. Effects on the Pulmonary System

During short-duration spaceflight, a host of changes to normal, physiologic pulmonary function have been observed [ 73 , 227 ]. Studies during parabolic flight have shown that the diaphragm and abdomen are displaced cranially due to microgravity, which is accompanied by an increase in the diameter of the lower rib cage with outward movement. Due to the observed changes to the shape of the chest wall, diaphragm, and abdomen, alterations to the pressure-volume curve resulted in a net reduction in lung volumes [ 228 ]. In five subjects who underwent 25 s of microgravity exposure during parabolic flight, functional residual capacity (FRC) and vital capacity (VC) were found to be reduced [ 229 ]. During the Spacelab Life Sciences-1 mission, microgravity exposure resulted in 10%, 15%, 10–20%, and 18% reductions in VC, FRC, expiratory reserve volume (ERV), and residual volume (RV), respectively, compared to values seen in Earth’s gravity [ 227 ]. The observed physiologic change in FRC is primarily due to the cranial shift of the diaphragm and abdominal contents described previously, and secondarily to an increase in intra-thoracic blood volume and more uniform alveolar expansion [ 227 ].

One surrogate measure for the inhomogeneity of pulmonary perfusion can be assessed through changes in cardiogenic oscillations of CO 2 (oscillations in exhaled gas composition due to differential flows from different lung regions with differing gas composition). Following exposure to microgravity, the size of cardiogenic oscillations were significantly reduced to 60% in comparison to the preflight standing values [ 230 , 231 ]. Possible causes of the observed inhomogeneity of ventilation include regional differences in lung compliance, airway resistance, and variations in motion of the chest wall and diaphragm. Access to arterial blood gas analysis would allow for enhanced physiologic evaluations, as well as improved management of clinical emergencies (e.g., pulmonary embolism) occurring during space travel. However, there is currently no suitable method for assessing arterial blood in space. The earlobe arterialized blood technique for collecting blood gas has been proposed, but evidence is limited [ 232 ]. Further research is required in this area to establish an effective means for sampling arterial blood during spaceflight.

In comparison to the changes seen during short-duration spaceflight, studies conducted during long-duration spaceflight showed that the heterogeneity of ventilation/perfusion (V/Q) was largely unchanged, with preserved gas exchange, VC, and respiratory muscle strength [ 73 , 233 , 234 ]. This resulted in overall normal lung function. This is supported by long-duration studies (up to 6 months) in microgravity which demonstrated that the function of the normal human lungs is largely unchanged following the removal of gravity [ 233 , 234 ]. It is worth noting that there were some small changes which were observed (e.g., an increase in ERV in the standing posture) following long-duration spaceflight, which can perhaps be attributed to a reduction in circulating blood volume [ 233 , 234 ]. However, while microgravity can causes temporary changes in lung function, these changes were reversible upon return to Earth’s gravity (even after 6 months of exposure to microgravity). Based on the currently available data, the overall effect of acute and sustained exposure to microgravity does not appear to cause any deleterious effects to gas exchange in the lungs. However, the biggest challenge for long-duration spaceflight is perhaps extraterrestrial dust exposure. Further research is required to identify the long term consequences of extraterrestrial dust exposure and develop potential countermeasures (e.g., specialized face masks) [ 73 ].

1.10. Effects on the Dermatologic System

During short-duration space travel, skin conditions such as contact dermatitis, skin sensitivity, biosensor electrolyte paste reactions, and thinning skin are common [ 44 , 235 ]. However, these conditions are generally mild and unlikely to significantly impact astronaut safety or prevent completion of space missions [ 44 ].

The greatest dermatologic concern for long-duration space travelers is the theoretical increased risk of developing skin cancer due to space radiation exposure. This hypothesis is supported by one study which found the rate of basal cell carcinoma, melanoma, and squamous cell carcinoma of the skin to be higher among astronauts compared to a matched cohort [ 236 ]. While the three-fold increase in prevalence was significant, there were a number of confounders (e.g., the duration of prolonged UV exposure on Earth for training or recreation, prior use of sunscreen protection, genetic predisposition, and variations in immune system function) that must also be taken into account. A potential management strategy for dealing with various skin cancers during space travel involves telediagnostic and telesurgical procedures. Further research is needed to improve the telediagnosis and management of dermatological conditions (e.g., adjustment for a lag in communication time) during spaceflight.

1.11. Diagnostic Imaging Modalities in Space

In addition to routine physical examination, various medical imaging modalities may be required to monitor and diagnose medical conditions during long-duration space travel. To date, ultrasound imaging acquired on space stations has proven to be helpful in diagnosing a wide array of medical conditions, including venous thrombosis, renal and biliary stones, and decompression sickness [ 29 , 237 , 238 , 239 , 240 , 241 , 242 ]. Moreover, the Focused Assessment with Sonography for Trauma (FAST), utilized by physicians to rapidly evaluate trauma patients, may be employed during space missions to rule out life-threatening intra-abdominal, intra-thoracic, or intra-ocular pathology [ 243 ]. Remote telementored ultrasound (aka tele-ultrasound) has been previously investigated during the NASA Extreme Environment Missions Operations (NEEMO) expeditions [ 244 ]. Today, the Butterfly iQ portable ultrasound probe can be linked directly to a smartphone through cloud computing, allowing physicians/specialists to promptly analyze remote ultrasound images [ 245 ].

Currently, alternative imaging modalities such as X-ray, CT, PET and MRI scan are unable to be used in space due to substantial limitations (e.g., limited space for large imaging structures, difficulties in interpretation due to microgravity). However, it is possible that the future development of a photocathode-based X-ray source may one day make this a possibility [ 101 , 246 ]. If X-ray imaging was possible, certain caveats would need to be taken into account for accurate interpretation. For example, pleural effusions, air-fluid levels, and pulmonary cephalization commonly seen on terrestrial imaging, would need to be interpreted in an entirely different way due to the effect of microgravity [ 247 ]. While this adjustment might be challenging, the altered principles of weightless physiology may provide some advantages as well. For example, one study found that intra-abdominal fluid was better able to be detected in space than in the terrestrial environment due to gravitational alterations in fluid dynamics [ 248 ]. Further research is required to identify and optimize inflight imaging modalities for the detection and treatment of various medical conditions.

1.12. Medical and Surgical Procedures in Space

Despite the presence of microgravity, both basic life support and advanced cardiac life support are feasible during space travel with some modifications [ 249 , 250 ]. For example, the recent guidelines for CPR in microgravity recommend specialized techniques for delivering chest compressions [ 251 ]. The use of mechanical ventilators, and moderate sedation or general anesthesia in microgravity are also possible but the evidence is extremely limited [ 252 , 253 ]. In addition, there are several procedures such as endotracheal intubation, percutaneous tracheostomy, diagnostic peritoneal lavage, chest tube insertion, and advanced vascular access which have only been studied through artificial stimulation [ 254 , 255 ].

Once traditionally “surgical” conditions are appropriately diagnosed, the next step is to determine whether these conditions should be managed medically, percutaneously, or surgically (laparoscopic vs. open procedures) [ 47 , 256 ]. For example, acute appendicitis or cholecystitis that would historically be managed surgically in terrestrial hospitals, could instead be managed with antibiotics rather than surgery. While the use of antibiotics for these conditions is usually effective on Earth, there remain concerns due to space-induced immune alterations, increased pathogenicity and virulence of microorganisms, and limited resources to “rescue” cases of antibiotic failure [ 39 ]. In cases of antibiotic failure, one potential minimally invasive option could be ultrasound-guided percutaneous drainage, which has previously been demonstrated to be possible and effective in microgravity [ 257 ]. Another potential approach is to focus on the early diagnosis and minimally invasive treatment of appropriate conditions, rather than treating late stage disease. In addition to expediting the patient’s post-operative recovery, minimally invasive surgery in space has the added benefit of protecting the cabin environment and the remainder of the crew [ 258 , 259 ].

As in all aspects of healthcare delivery in space, the presence of microgravity can complicate even the most basic of procedures. However, based on collective experience to date, if the patient, operators, and all required equipment are restrained, the flow of surgical procedures remains relatively unchanged compared to the traditional, terrestrial experience [ 260 ]. A recent animal study confirmed that it was possible to perform minor surgical procedures (e.g., vessel and wound closures) in microgravity [ 261 ]. Similar study during parabolic flight has further confirmed that emergent surgery for the purpose of “damage control” in catastrophic scenarios can be conducted in microgravity [ 262 ]. As discussed previously, telesurgery may be feasible if the surgery can be performed with an acceptably brief time lag (<200 ms) and if the patient is within a low Earth orbit [ 263 , 264 ]. However, further research and technological advancements are required for this to come to fruition.

1.13. Lifestyle Management in Space

Based on microgravity simulation studies, NASA has proposed several potential biomedical countermeasures in space [ 33 , 160 , 161 ]. Mandatory exercise protocols in space are crucial and can be used to maintain physical fitness and counteract the effects of microgravity. While these protocols may be beneficial, exercise alone may not be enough to prevent certain effects of microgravity (e.g., an increase in arterial thickness/stiffness) [ 20 , 265 , 266 , 267 ]. For example, a recent study found that resistive exercise alone could not suppress the increase in bone resorption that occurs in space [ 20 ]. Hence, a combination of resistance training and an antiresorptive medication (e.g., bisphosphonate) appears to be optimal for promotion of bone health [ 20 , 21 ]. Further research is needed to identify the optimal exercise regimen including recommended exercises, duration, and frequency.

In addition to exercise, dietary modification may be another potential area for optimization. The use of a diet based on caloric restriction (CR) in space remains up for debate. Based on data from terrestrial studies, caloric restriction may be useful for improving vascular health; however, this benefit may be offset by the associated muscle atrophy and osteoporosis [ 268 , 269 ]. Given that NASA encourages astronauts to consume adequate energy to maintain body mass, there has been an attempt to mimic the positive effects of CR on vascular health while providing appropriate nutrition. Further research is needed this area to identify the ideal space diet.

Based on current guidelines, only vitamin D supplementation during space travel is recommended. Supplementation of A, B6, B12, C, E, K, Biotin, folic acid are not generally recommended at this time due to insufficient evidence [ 64 ] ( Table S3 ). The use of traditional prescription medications may not function as intended on Earth. Therefore, alternative methods such as synthetic biologic agents or probiotics may be considered [ 35 , 38 ]. However, evidence in this area is extremely limited, and it is possible that the synthetic agents or probiotics may themselves be altered due to microgravity and radiation exposure. Further research is needed to investigate the relationship between these supplements and potential health benefits in space.

Currently, most countermeasures are directed towards cardiovascular system and musculoskeletal pathologies but there is little data against issues like immune and sleep deprivation, SANS, skin, etc. Artificial Gravity (AG) has been postulated as adequate multi-system countermeasure especially the chronic exposure in a large radius systems. Previously, the main barrier is the huge increase in costs [ 270 , 271 , 272 ]. However, there are various studies that show the opposite and also the recent decrease in launch cost makes the budget issue nearly irrelevant especially when a huge effort is paid to counteract the lack of gravity. The use of AG especially long-radius chronic AG is feasible. Further studies are needed to determine the utilization of AG in long-duration space travel.

1.14. Future Directions for Precision Space Health with AI

In this new era of space travel and exploration, ‘future’ tools and novel applications are needed in order to prepare deep space missions, particularly pertaining to strategies for mitigating extraterrestrial environmental factors, including both exogenous and en-dogenous processes. Such ‘future’ tools could help assist and ensure a safe travel to deep space, and more importantly, help bring space travelers and astronauts back to Earth. These tools and methods may initially be ‘remotely’ controlled, or have its data sent back to Earth for analysis. Primarily efforts should be focused on analyzing data in situ, and on site during the mission itself, both for the purpose of efficiency, and for the progressive purpose of slowly weaning off a dependency on Earth.

AI is an emerging tool in the big data era and AI is considered a critical aspect of ‘fu-ture’ tools within the healthcare and life science fields. A combination of AI and big data can be used for the purposes of decision making, data analysis and outcome prediction. Just recently, there have been encourage in advancements in AI and space technologies. To date, AI has been employed by astronauts for the purpose of space exploration; however, we may just be scratching the surface of AI’s potential. In the area of medical research, AI technology can be leveraged for the enhancement of telehealth delivery, improvement of predictive accuracy and mitigation of health risks, and performance of diagnostic and interventional tasks [ 273 ]. The AI model can then be trained and have its inference leveraged through cloud computing or Edge TPU or NVIDIA Jetson Nano located on space stations. ( Table 3 and Table S4 ) Figure 3 demonstrates potential AI applications in space.

Potential AI applications in space.

As described previously, the capability to provide telemedicine beyond LEO is primarily limited by the inability to effectively communicate between space and Earth in real-time [ 274 ]. However, AI integration may be able to bridge the gap and advance communication capabilities within the space environment [ 275 , 276 ]. One study demonstrated a potential mechanism for AI incorporation in which an AI-generated predictive algorithm displayed the projected motion of surgical tools to adjust for excess communication lag-time [ 277 ]. This discovery could potentially enable AI-enhanced robotics to complete repetitive, procedural tasks in space without human inputs (e.g., vascular access) [ 278 ]. Today, procedures performed with robotic assistance are not yet fully autonomous (they still require at least one human expert). It is possible with future iterations that an AI integration could be created with the ability to fully replicate the necessary human steps to make terrestrial procedures (e.g., percutaneous coronary intervention, incision and drainage [ 103 ], telecholecystectomy [ 105 , 106 ], etc.) feasible in space [ 275 , 279 ]. The seventh NEEMO mission previously demonstrated that robotic surgery controlled by a remote physician is feasible within the environment of a submarine, but it remains to be seen whether this can be expanded to the space environment [ 280 ].

On space stations, Edge TPU-accelerated AI inference could be used to generate accurate risk prediction models based on data obtained from simulated environments (e.g., NASA AI Risk Prediction Challenge) [ 281 ]. For example, AI could potentially utilize data (e.g., -omics) obtained from research conducted both on Earth and in simulated environments (e.g., NASA GCR Simulator) to predict an astronaut’s risk of developing cancer due to high-LET radiation exposure (cytogenetic damage, mitochondrial dysregulation, epigenetic alterations, etc.) [ 63 , 78 , 79 , 282 , 283 , 284 ].

Another potential area for AI application is through integration with wearable technology to assist in the monitoring and treatment of a variety of medical conditions. For example, within the field of cardiovascular medicine, wearable sensor technology has the capability to detect numerous biosignals including an individual’s cardiac output, blood pressure, and heart rate [ 285 ]. AI-based interpretation of this data can facilitate prompt diagnosis and treatment of congestive heart failure and arrhythmias [ 285 ]. In addition, several wearable devices in various stages of development are being created for the detection and treatment of a wide array of medical conditions (obstructive sleep apnea, deep vein thrombosis, SMS, etc.) [ 285 , 286 , 287 , 288 ].

As discussed previously, the confinement and social isolation associated with prolonged space travel can have a profound impact on an astronaut’s mental health [ 8 , 10 , 67 ]. AI-enhanced facial and voice recognition technology can be implemented to detect the early signs of depression or anxiety better than standardized screening questionnaires (e.g., PHQ-9, GAD-7) [ 68 , 69 ]. Therefore, telepsychology or telepsychiatry can be used pre-emptively for the diagnosis of mental illness [ 68 , 69 , 289 ].

2. Conclusions

Over the next decade, NASA, Russia, Europe, Canada, Japan, China, and a host of commercial space companies will continue to push the boundaries of space travel. Space exploration carries with it a great deal of risk from both known (e.g., ionizing radiation, microgravity) and unknown risk factors. Thus, there is an urgent need for expanded research to determine the true extent of the current limitations of long-term space travel and to develop potential applications and countermeasures for deep space exploration and colonization. Researchers must leverage emerging technology, such as AI, to advance our diagnostic capability and provide high-quality medical care within the space environment.

Acknowledgments

The authors would like to thank Tyson Brunstetter, (NASA Johnson Space Center, Houston, TX) for his suggestions and comments on this article as well as providing the update NASA’s SANS Evidence Report, Ajitkumar P Mulavara, (Neurosciences Laboratory, KBRwyle, Houston, TX), Jonathan Clark, (Neurology & Space Medicine, Center for Space Medicine, Houston, TX), Scott M. Smith, (Nutritional Biochemistry, Biomedical Research and Environmental Sciences Division, Human Health and Performance Directorate, NASA Johnson Space Center, Houston, TX) for his suggestions and providing the update NASA’s Nutrition Report, G. Kim Prisk, (Department of Medicine, Division of Physiology, University of California, San Diego, La Jolla, CA), Lisa C. Simonsen (NASA Langley Research Center, Hampton, VA), Siddharth Rajput, (Royal Australasian College of Surgeons, Australia and Aerospace Medical Association and Space Surgery Association, USA), David S. Martin, MS, (KBR, Houston, TX), ‪David W. Kaczka, (Department of Anesthesia, University of Iowa Carver College of Medicine, Iowa City, Iowa), Benjamin D. Levine (Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, University of Texas Southwestern Medical Center), Afshin Beheshti (NASA Ames Research Center), Christopher Wilson (NASA Goddard Space Flight Center), Michael Lowry (NASA Ames Research Center), Graham Mackintosh (NASA Advanced Supercomputing Division), and staff from NASA Goddard Space Flight Center for their suggestions. In addition, the authors would like to thank the anonymous reviewers for their careful reading of our manuscript, constructive criticism, and insightful comments and suggestions.

Abbreviations

Supplementary materials.

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/cells12010040/s1 , Table S1: title Summary of gut microbial alteration during spaceflight; Table S2: title Summary of immune/cytokine changes during spaceflight; Table S3: title Summary of diet recommendation during spaceflight; Table S4: title Summary of AI technology and potential applications in space.

Funding Statement

This research received no external funding.

Conflicts of Interest

Krittanawong discloses the following relationships-Member of the American College of Cardiology Solution Set Oversight Committee, the American Heart Association Committee of the Council on Genomic and Precision Medicine, the American College of Cardiology/American Heart Association (ACC/AHA) Joint Committee on Clinical Data Standards (Joint Committee), and the American College of Cardiology/American Heart Association (ACC/AHA) Task Force on Performance Measures, The Lancet Digital Health (Advisory Board), European Heart Journal Digital Health (Editorial board), Journal of the American Heart Association (Editorial board), JACC: Asia (Section Editor), and The Journal of Scientific Innovation in Medicine (Associate Editor). Other authors have no disclosure.

Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Suggested Searches

• Climate Change
• Expedition 64
• Mars perseverance
• SpaceX Crew-2
• International Space Station
• View All Topics A-Z
• Humans in Space

Earth & Climate

The solar system, the universe, aeronautics, learning resources, news & events.

New NASA Sonifications Listen to the Universe’s Past

What’s Up: September 2024 Skywatching Tips from NASA

NASA Mission Gets Its First Snapshot of Polar Heat Emissions

• Search All NASA Missions
• A to Z List of Missions
• Upcoming Launches and Landings
• Spaceships and Rockets
• Communicating with Missions
• James Webb Space Telescope
• Hubble Space Telescope
• Why Go to Space
• Commercial Space
• Destinations

Living in Space

• Explore Earth Science
• Earth, Our Planet
• Earth Science in Action
• Earth Multimedia
• Earth Science Researchers
• Pluto & Dwarf Planets
• Asteroids, Comets & Meteors
• The Kuiper Belt
• The Oort Cloud
• Skywatching
• The Search for Life in the Universe
• Black Holes
• The Big Bang
• Dark Energy & Dark Matter
• Earth Science
• Planetary Science
• Astrophysics & Space Science
• The Sun & Heliophysics
• Biological & Physical Sciences
• Lunar Science
• Citizen Science
• Astromaterials
• Aeronautics Research
• Human Space Travel Research
• Science in the Air
• NASA Aircraft
• Flight Innovation
• Supersonic Flight
• Air Traffic Solutions
• Green Aviation Tech
• Drones & You
• Technology Transfer & Spinoffs
• Space Travel Technology
• Technology Living in Space
• Manufacturing and Materials
• Science Instruments
• For Kids and Students
• For Educators
• For Colleges and Universities
• For Professionals
• Science for Everyone
• Requests for Exhibits, Artifacts, or Speakers
• STEM Engagement at NASA
• NASA's Impacts
• Centers and Facilities
• Directorates
• Organizations
• People of NASA
• Internships
• Our History
• Doing Business with NASA
• Get Involved

NASA en Español

• Aeronáutica
• Ciencias Terrestres
• Sistema Solar
• All NASA News
• Video Series on NASA+
• Newsletters
• Social Media
• Media Resources
• Upcoming Launches & Landings
• Virtual Guest Program
• Image of the Day
• Sounds and Ringtones
• Interactives
• STEM Multimedia

NASA Invites Social Creators to Experience Launch of Europa Clipper Mission

NASA’s Mini BurstCube Mission Detects Mega Blast

NASA-Funded Research Institute Seeks Space Health Postdoctoral Fellows

NASA, Boeing Optimizing Vehicle Assembly Building High Bay for Future SLS Stage Production

NASA Seeks Input for Astrobee Free-flying Space Robots

NASA JPL Developing Underwater Robots to Venture Deep Below Polar Ice

NASA Project in Puerto Rico Trains Students in Marine Biology

NASA, ESA Missions Help Scientists Uncover How Solar Wind Gets Energy

September’s Night Sky Notes: Marvelous Moons

Hubble Zooms into the Rosy Tendrils of Andromeda

NASA Earth Science Education Collaborative Member Co-Authors Award-Winning Paper in Insects

NASA G-IV Plane Will Carry Next-Generation Science Instrument

NASA Develops Pod to Help Autonomous Aircraft Operators 

NASA Composite Manufacturing Initiative Gains Two New Members

First NASA-Supported Researcher to Fly on Suborbital Rocket

How Do I Navigate NASA Learning Resources and Opportunities?

Carbon Nanotubes and the Search for Life on Other Planets

235 Years Ago: Herschel Discovers Saturn’s Moon Enceladus

Preguntas frecuentes: Estado del retorno de la prueba de vuelo tripulado Boeing de la NASA

Astronauta de la NASA Frank Rubio

Diez maneras en que los estudiantes pueden prepararse para ser astronautas

The human body in space.

Nathan Cranford

Jennifer Turner

Space radiation, isolation and confinement, distance from earth, gravity fields, hostile/closed environments.

For more than 50 years, NASA’s  Human Research Program (HRP) has studied what happens to the human body in space. Researchers are using what they learn to design procedures, devices, and strategies to keep astronauts safe and healthy throughout their missions.

NASA engineers use the lessons learned to better design spacecraft and improve the fit and functions of spacesuits. The research also aids in the development and assessment of medical standards, physical fitness programs and standards, physiological and psychological adaptation training, sensorimotor training, and nutritional health protocols.

Understanding the effects of spaceflight on humans is essential as astronauts move from the  International Space Station in low-Earth orbit to deep space destinations on and around the Moon, and beyond. With the  Artemis program , NASA will land the first woman and next man on the Moon using innovative technologies to explore more of the lunar surface than ever before, gathering new data while keeping astronauts healthy and safe.

NASA is particularly interested in investigating how the body reacts to long-duration spaceflight as the agency plans for extended missions on the Moon and Mars.  Scott Kelly  and Christina Koch were the first American astronauts to spend nearly one year in space onboard the space station, twice the previous average. Scott, Christina, and seven other astronauts have spent  more than 200 days in space during a single spaceflight .

In addition to spending almost a year in space, Scott was involved in the unique  Twins Study . Scott participated in several biomedical studies onboard the space station while his identical twin brother, retired astronaut Mark Kelly, stayed on Earth as a control subject, someone who provides a basis of comparison.

The study provided valuable data about what happened to Scott, physiologically and psychologically, as compared to his brother Mark. Their contribution to science helped generate data that researchers will use for decades to come.

NASA is planning more dedicated extended-duration research on the space station. The studies are expected to shed light on how the body adapts to living in the spaceflight environment for various longer time periods, which will be pivotal for future deep space missions.

What exactly happens to the body in space and what are the risks? Are the risks the same for astronauts who spend six months on the space station versus those who may be away on a Mars mission for years?

The simple answer is: No. NASA is researching risks for Mars missions which are grouped into five human spaceflight hazards related to the stressors they place on the body. These can be summarized with the acronym “ RIDGE ,” short for Space  R adiation,  I solation and Confinement,  D istance from Earth,  G ravity fields, and Hostile/Closed  E nvironments .

On Earth, we are shielded by the planet’s magnetic field and atmosphere from the majority of particles that make up the  space radiation  environment. Even so, everyone on Earth is exposed to low levels of radiation every day, from the food we eat to the air we breathe .  

In space, astronauts are exposed to varied and increased levels of radiation that are different from those on Earth. Three major sources contribute to the space radiation environment: particles trapped in Earth’s magnetic field, solar energetic particles from the Sun, and galactic cosmic rays.

A big challenge in reducing the risks of radiation exposure is that some space radiation particles (especially galactic cosmic rays) are difficult to shield against. Exposure to increased radiation can be associated with both short- and long-term health consequences, depending on how much total radiation astronauts experience and the time frame in which they experience that exposure.

Increased risk of  cancer  and  degenerative diseases , such as heart disease and cataracts, have been observed in human populations exposed to radiation on Earth. Health risks for astronauts from radiation exposure in space are mainly driven by long-term impacts.

Additionally, animal and cellular research indicate that the type of radiation in the space environment has a larger impact on health outcomes compared to the radiation experienced on Earth. Not only will astronauts be exposed to more radiation in space than on Earth, but the radiation they are exposed to could pose increased risks.

The Key:  The  current strategy  to reduce the health risks of space radiation exposure is to implement shielding, radiation monitoring, and specific operational procedures. Compared to typical six-month space station missions, later Moon and Mars missions will be much longer on average. Consequently, the total amount of radiation experienced and associated health risks may increase.

NASA is developing new radiation detectors to  monitor  and characterize the radiation environment, which will provide better estimates of the dose and type of radiation to which the crews are exposed. Scientists and engineers are optimizing and implementing operational procedures that use available vehicle stowage and materials to reduce radiation exposure effectively.

To investigate the health risks of space radiation exposure beyond low-Earth orbit, NASA supports research that analyzes the biological effects of simulated cosmic rays at  ground-based research facilities . Research at these facilities helps NASA understand and reduce the risk of space radiation, ensure proper measurement of the doses that astronauts receive on the space station and in future spacecraft, and develop advanced materials that improve radiation shielding for future missions.

Studies of radiation-exposed human cohorts are also being conducted to estimate the health risks in populations relevant to astronauts.

Expedition crews selected for a stay onboard the space station are carefully chosen, trained, and supported to ensure they will be able to work effectively as a team for the duration of their six to 12-month missions. Crews for a Moon or Mars mission will undergo even more careful assessment, selection, and preparation since they will travel farther and potentially for longer than previous humans in an isolated and confined environment, with only a few other people. Additionally, crews will likely be international and multi-cultural, making cross-cultural sensitivity and team dynamics paramount to mission success.

Ensuring astronauts get quality sleep is also important; otherwise, their internal biological clocks, or  circadian rhythm , might be altered by factors like different dark and light cycles, a small and noisy environment, the stress of prolonged isolation and confinement, and a 37-minute extended day on Mars.

It is important to prepare for the fatigue astronauts may experience during spaceflight, given that there will be times with heavy workloads and shifting schedules. To prevent crew boredom, NASA considers the kinds of activities in which the astronauts will participate during a multi-year round trip to Mars.

Communication and understanding among crew members are vital to the success of the mission, and changes in morale and motivation are possible as the mission unfolds. This may relate to reduced stimulation, the longing for loved ones, or feeling unable to assist with family emergencies back on Earth, regardless of how long the mission lasts.

Using spaceflight analogs on Earth, NASA’s research has revealed that both the duration and type of confined and isolated experience are important to consider. The more restricted the space, and the less contact with people outside the environment, the more likely humans are to develop behavioral or cognitive conditions or psychiatric disorders.

The Key:  NASA has been studying people in isolated and confined environments for years, and has developed methods and technologies to counteract possible problems.

NASA scientists are using devices, such as actigraphy, that help assess and improve sleep and alertness by recording how much people move and how much ambient light is around them. New lighting, spurred by the development of Light-Emitting Diode (LED) technology, is used on the space station to help align astronaut’s circadian rhythms and to improve sleep, alertness, and performance.

A 10-minute self-test of vigilance and attention assesses the effect of fatigue on performance. Astronauts write in journals as a safe place to vent frustrations and provide researchers a tool to study behavioral issues that are on the minds of crew members who are living and working in isolation and confinement.

Researchers are also looking into using virtual reality to simulate relaxing environments to help improve the mood of crews in isolation. Engaging in relevant, meaningful activities, including learning a language or learning new medical skills, could help ward off depression and boost morale. Crews may even tend to a  space garden , which could have positive behavioral health benefits in addition to providing a fresh source of food and helping to purify the air.

Researchers are using Earth-based analogs to investigate how much   privacy and living space will be needed on longer missions where crew members will be restricted in a relatively small spacecraft together. NASA is also determining strategies to formulate the best  crew  by studying individual and team attributes, composition, and dynamics.

The space station orbits 240 miles above Earth. The Moon is 1,000 times farther from Earth than the space station. In contrast, Mars is on average  140 million miles  from Earth. With a communication delay of up to  20 minutes  one-way while on Mars, astronauts must be able to solve problems and identify solutions as a team without help from NASA’s mission control.

The types of food and medicine to be packed for a multi-year trip without access to a grocery store or pharmacy are also important to consider. Unlike space station crews, which regularly receive supplies from cargo flights from Earth, astronauts going to Mars will have to bring all of the food, equipment, and medical supplies they need.

The Key:  NASA is using its human spaceflight experience on the space station to figure out what types of medical events happen in space over time and what types of skills, procedures, equipment, and supplies are needed so that they will have a good idea of what to pack for future missions to the Moon and Mars.

Space station astronauts already receive medical training before and during space missions that teach them how to respond to health problems as they arise. For example, astronauts learn how to use onboard space station equipment to produce an intravenous (IV) solution from purified water, which can be used for medical administration.

Crew members also perform  ultrasound scans  on each other to monitor organ health. If one crew member becomes sick during the mission, crews are ready to perform laboratory testing to help make the right diagnosis and guide treatment.

NASA is working on developing a medical data architecture for spacecraft that enables the capabilities of  clinical decision support tools , which could use artificial intelligence and machine learning to further help diagnose and treat various illnesses. Researchers are also looking into the role that virtual assistants could play to help crews identify and respond to spaceflight anomalies quickly for more distant missions.

Additionally, the agency is studying and improving  food formulation , processing, packaging, and preservation systems to ensure the nutrients remain stable and the food remains acceptable for years. Space-resilient medications and packaging systems that preserve the integrity of pharmaceuticals for long-duration missions are another significant part of NASA’s research.  

Astronauts will encounter three different gravity fields on a Mars mission. On the six-month trek between the planets, crews will be weightless. While living and working on Mars, crews will be in approximately one-third of Earth’s gravity. Finally upon returning home, crews will have to readapt to Earth’s gravity.

Transitioning from one gravity field to another is trickier than it sounds. It affects spatial orientation, head-eye and hand-eye coordination, balance, and locomotion, with some crew members experiencing space motion sickness.

Landing a spacecraft on Mars could be challenging as astronauts adjust to the gravity field of another celestial body. When shifting from weightlessness to gravity, astronauts may experience post-flight orthostatic intolerance where they are unable to maintain their blood pressure when standing up, which can lead to lightheadedness and fainting.

NASA has learned that without Earth’s gravity affecting the human body, weight-bearing bones lose on average  1% to 1.5%  of mineral density per month during spaceflight. After returning to Earth, bone loss might not be completely corrected by rehabilitation; however, their risk for fracture is not higher. Without the proper diet and exercise routine, astronauts also lose muscle mass in microgravity faster than they would on Earth.

Moreover, the fluids in the body shift upward to the head in microgravity, which may put pressure on the eyes and cause vision problems. If preventive or countermeasures are not implemented, crews may experience an increased risk of developing kidney stones due to dehydration and increased excretion of calcium from their bones.

The Key:  By analyzing how the body changes in weightlessness and after returning to Earth’s gravity, NASA is developing protective measures against these changes for a Mars mission.

Functional task testing is in place to help detect and improve balance control after landing on a gravitational surface.  Fine motor skill testing is done to detect any changes in the ability of astronauts to interact with computer-based devices.

Distribution of the fluids in the body is closely monitored to help evaluate any connection to changes in  vision. Compression cuffs worn on the thighs help keep the blood in the lower extremities to counteract those fluid shifts. A lower-body negative pressure device could help draw fluids from the head into the legs as well.

Back pain, which some astronauts have reported experiencing during spaceflight, is monitored by obtaining  spinal ultrasounds . Muscle size and bone density are assessed for deterioration using MRI and high-resolution imaging techniques, before and after flight. Crew members perform periodic fitness self-evaluations  to help researchers better understand the decline in heart function that can occur during spaceflight.

Medicines that NASA is studying, such as potassium citrate, may help combat the physiological change that could increase the risk of developing kidney stones. Bisphosphonate medications have been shown in NASA studies to be effective in preventing bone loss.

NASA has also designed an efficient way to collect and measure how much urine a crew member produces in space, which is essential to human research since it reveals key information about a person’s health. For example, researchers can analyze different levels of certain substances in an astronaut’s urine to determine whether they are at risk of developing a  kidney stone  in space, and make modifications to the diet, exercise routine, and water intake as preventive measures.

Aerobic and resistive exercise has been shown to keep the heart healthy,  bones and muscles strong , the mind alert, as well as maintain a more positive outlook, and may even help with  balance and coordination . Software-generated workout partners could be used to help motivate astronauts to exercise regularly for longer space missions. NASA has even completed a joint Earth-based bed rest study to determine whether centrifuge artificial gravity  may be an effective way to counter the physiological effects of weightlessness.

NASA has learned that the ecosystem inside the spacecraft plays a big role in everyday astronaut life in space. Microbes can change characteristics in space, and micro-organisms that naturally live on the human body are transferred more easily from person to person in closed habitats, such as the space station. Stress hormone levels are elevated and the immune system is altered, which could lead to increased susceptibility to allergies or other illnesses.

Earth-based analogs do not perfectly simulate the spaceflight environment, making them insufficient for studying on the ground how human immune systems react in space. However, NASA-funded Antarctic analog studies could provide insight into how certain spaceflight stressors may affect the human immune system. What is known is that spaceflight changes the immune system, although crews do not tend to get sick upon returning to Earth. Even though astronauts’ acquired immunity is intact, more research is needed into whether spaceflight induced altered immunity may lead to autoimmune issues, in which the immune system mistakenly attacks the healthy cells, organs, and tissues present in the body.

Beyond the effects of the environment on the immune system, every inch and detail of living and working quarters must be carefully thought-out and designed. No one wants their house to be too hot, too cold, cramped, crowded, loud, or not well lit, and no one would enjoy working and living in such a habitat in space either.

The Key:  NASA is using technology to monitor the air quality of the space station to ensure the atmosphere is safe to breathe and not contaminated with gases, such as formaldehyde, ammonia, and carbon monoxide.  Thermal Control Systems  function to maintain temperatures of the space station and keep astronauts comfortable.

Blood and saliva samples are analyzed to identify changes in the immune system and the reactivation of latent viruses during spaceflight. NASA uses advanced molecular techniques to evaluate the risk of microbes that may cause illness for crew members. Various parts of the body and the space station are swabbed regularly for analysis of the microbial population that inhabits the environment. Crews change out air filters, clean surfaces, and treat the water to prevent illnesses that may result from the accumulation of contaminants.

Astronauts are advised to get a  flu  shot to boost their immunity and are  quarantined  before their missions to avoid catching any sort of illness before launch. During the Twins Study and One-Year Mission, Scott Kelly administered a flu vaccine to himself while his brother received his on Earth. The immunization proved to work as well in space as it does on Earth, which is a good finding for longer missions to the Moon and Mars.

Living quarters and work environments are carefully planned and evaluated to ensure that designs balance comfort and efficiency. Lighting onboard the space station is similar to what would be experienced naturally on Earth, thanks to the new  LED  lighting system.    

NASA is taking action on all of these risks and working to solve the challenges of human spaceflight with some of the most brilliant minds in their fields. The results garnered from laboratories, ground analogs, and space station missions will provide more insight into these adaptations and present a stepping stone for longer missions.

On upcoming Artemis missions to lunar orbit and the surface of the Moon, even more data will be collected as this work continues. On future longer duration missions to the Moon and Mars, astronauts will benefit from years of research that will ensure they will be able not just to survive, but thrive on their spacefaring missions.

Click here for an infographic summarizing the risks of human spaceflight and the safeguards against them .

NASA’s  Human Research Program , or HRP, pursues the best methods and technologies to support safe, productive human space travel. Through science conducted in laboratories, ground-based analogs, and the International Space Station, HRP scrutinizes how spaceflight affects human bodies and behaviors. Such research drives HRP’s  quest  to innovate ways that keep astronauts healthy and mission-ready as space travel expands to the Moon, Mars, and beyond.

For a 508 Compliant PDF of this post, follow this link.

Related Terms

Human Research Program

Explore More

NASA Funds Studies to Support Crew Performance on Long-Duration Missions

Discover more topics from nasa.

Space Station Research and Technology

• Skip to main content
• Keyboard shortcuts for audio player

Your Health

• Treatments & Tests
• Health Inc.
• Public Health

Why do some people get rashes in space? There's a clue in astronaut blood

Canadian astronaut David Saint-Jacques has his blood sampled on board the International Space Station for an experiment that examines the space-related changes that occur in blood and bone marrow. NASA hide caption

Canadian astronaut David Saint-Jacques has his blood sampled on board the International Space Station for an experiment that examines the space-related changes that occur in blood and bone marrow.

Astronauts are supposed to be in excellent health. It's part of the job description. They quarantine before blasting off to avoid getting sick and derailing a mission. Once aloft, they live and work in a sterile environment.

And yet, when they get to outer space, some have viral flareups or break out in rashes. It's a puzzle that got Odette Laneuville , a molecular biologist at the University of Ottawa, asking herself, "Why is it that they get infections up there?"

In a new study in Frontiers in Immunology , Laneuville and her colleagues suggest it could be due to the reduced activity of one hundred immune-related genes, which help give opportunistic infections a toehold.

40 years ago, Sally Ride became the first American woman in space

Knowing what causes astronauts to be more vulnerable to infections could help make future missions to space safer, experts say — and may improve treatments for those who are immunocompromised back here on Earth.

Normally, Laneuville says our bodies host a multitude of viruses and bacteria at any given moment — even when we feel just fine.

"And because we're healthy, we manage to keep those at check and dormant," she says. "But if we're stressed or if there's a dysregulation of the immune system," then those viruses and bacteria can cause infections. Laneuville thought maybe something in space was triggering a change in the gene activity of of the immune cells in astronaut blood that was allowing these opportunistic infections to surface.

So she and her colleagues enlisted 14 American and Canadian astronauts — all headed to the International Space Station for several months at different times. Laneuville had their blood sampled before and after their missions here on Earth, but also during their time in outer space. The 10-minute procedure on land took 90 minutes in orbit.

"They have to be very careful to pull out all their equipment, the needles, the tubes. And they have to secure everything," Laneuville says. "We don't want any leak. Not a drop of blood. Otherwise, it will float in the air and contaminate everybody."

The astronauts spun the blood down and stored it in a super-cold freezer until they returned to Earth, samples in tow. "I was supposed to hire someone to process those," she says. "But then I said, 'No, they're too precious. This blood comes from space.' It was my baby and I had to take care of it."

Ottawa-based researchers Dr. Odette Laneuville (left) and Dr. Guy Trudel (right) were part of a team that studied how the space environment affects astronauts' blood. University of Ottawa hide caption

Ottawa-based researchers Dr. Odette Laneuville (left) and Dr. Guy Trudel (right) were part of a team that studied how the space environment affects astronauts' blood.

All told, across multiple missions to the International Space Station, it took five years to collect all the samples. "One has to be very patient," says Laneuville. "But it's worth waiting. I was gonna wait more if I had to."

Here's what that special blood revealed. Exactly one hundred immune-related genes get dialed down in outer space. It could be due to stress. But Laneuville thinks there's another possibility: "Those genes respond to a decrease in gravitational force."

She says that when an astronaut enters microgravity, their blood shifts from their legs to their torsos and heads. It's uncomfortable and throws things out of whack. Their body resolves the problem by reducing the fluid by up to 15%. But that now means that there are too many immune cells crammed into this smaller amount of blood.

Laneuville thinks the drop in gene activity helps eliminate those extra cells. And this in turn affects the way the immune system responds to pathogens.

"It's as if the body is telling them, 'Don't defend, put your guards down,'" she says.

And this would allow viral and bacterial infections — normally held at bay — to rise up, infecting the astronauts.

But once they step foot on land again, the whole thing reverses as the genes are dialed back up and fluid levels return to normal. This reversal takes no longer than a year, but for many genes it's only a matter of a few weeks.

NASA assigns astronauts to enter lunar orbit for the first time in decades

Down the road, the study may have something to say about those with compromised immune systems right here on Earth, says Brian Crucian, a research immunologist at NASA who wasn't involved in the work.

"Think about a transplant patient," or someone who's elderly or under a large amount of stress. "There are a lot of ties between astronauts and terrestrial medicine."

People who spend long periods of time in Antarctica may also benefit from this research. With these individuals, "you run them through difficult travel to a profoundly extreme environment," says Crucian. "You put them in a base for a year, they experience 24-hour darkness, 24-hour daylight. And so you've got almost everything but microgravity and radiation in the Antarctic."

This study is a good start, says Jeremy Teo , a biomedical engineer at NYU Abu Dhabi who wasn't part of the research.

As we send astronauts farther and father out — to the Moon and even Mars — experts say it will be harder to get them back to Earth for recovery or expedient treatment.

"The feasibility of extraditing compromised astronauts back to Earth is just not there anymore," says Teo. "And hence, we need to develop these new countermeasures to cater to these space travel stresses on the immune system."

• Infectious Disease
• immune system
• space travel
• immune suppression
• outer space

Advertisement

Astronaut medical records reveal the health toll of space travel

The largest collection yet of detailed medical data and tissue samples from astronauts should help researchers better understand the impacts of space flight on health

By Clare Wilson

11 June 2024

Astronauts Robert L. Curbeam Jr. (left) and Christer Fuglesang on the International Space Station

More light could be shed on how space flight affects astronauts’ health after the creation of the first “space-omics” biobank – a collection of thousands of blood and tissue samples, plus medical information, taken over multiple space missions.

These include missions to the International Space Station, as well as the first all-civilian space flight, SpaceX’s Inspiration4 , which took four non-government-trained astronauts into space for three days in 2021.

Called the Space Omics and Medical Atlas (SOMA), the resource contains detailed medical data, such as on DNA damage and changes in people’s gene activity and immune system functioning, collectively known as biomarkers.

Is the universe conscious? It seems impossible until you do the maths

Space flight is known to pose certain health risks. For instance, astronauts lose bone density and muscle mass due to the lack of gravity, and higher levels of radiation in space seem to cause cell and DNA damage, which have a range of impacts on the body. These effects may be why astronauts are more prone to developing heart disease in later life and some have experienced worsening vision after being in space.

Collecting astronauts’ medical data in a consistent way via the SOMA biobank will help researchers understand more about these changes and potentially develop ways to mitigate them, says Christopher Mason at Weill Cornell Medicine in New York, who helped put the biobank together.

Sign up to our Health Check newsletter

Get the most essential health and fitness news in your inbox every Saturday.

“Biomarkers don’t always translate into anything that’s clinically meaningful, but it’s a nice way to start to understand how this unique environment is impacting us,” says Damian Bailey at the University of South Wales in the UK, who wasn’t involved in the work.

One insight from the Inspiration4 mission is that, despite the astronauts experiencing a host of biomarker changes, most measurements returned to normal within a few months of them coming back to Earth .

This suggests that sending civilians into space doesn’t pose more health risks than sending professional astronauts, says Mason. “Instead of people training for decades to go, we could start to really open up space towards more and more people.”

The results from Inspiration4, which was crewed by two men and two women, also suggest that the changes in gene activity returned to normal faster in the women. That may be because women’s bodies have to be able to cope with a potential pregnancy , says Mason. “Being able to tolerate large changes in physiology and fluid dynamics may be great for being able to manage pregnancy, but also manage the stress of spaceflight.”

Why the big bang may not have been the beginning of the universe

Timothy Etheridge at the University of Exeter in the UK says it will be helpful for researchers around the world to have a common resource they can use. “You need to have a consistent approach to collecting samples,” he says.

Thomas Smith at King’s College London says understanding the health impacts of space flight will become more important if longer missions happen, such as journeys to Mars. “Anything that leads to extended duration missions, it’s more important to know what’s going on and, ideally, address it,” he says.

Journal reference:

Nature DOI: 10.1038/s41586-024-07639-y

• astronaut /

Sign up to our weekly newsletter

Receive a weekly dose of discovery in your inbox! We'll also keep you up to date with New Scientist events and special offers.

More from New Scientist

Explore the latest news, articles and features

Scientists wonder if space tourists will want to have sex in orbit

Subscriber-only

Space flight may increase erectile dysfunction among astronauts

How-to guide for CPR in space may help treat astronaut cardiac arrest

Data leak means anyone can see when astronauts urinate on the ISS

Popular articles.

Trending New Scientist articles

NASA scientists consider the health risks of space travel

Humans aren't built to live in space, and being there can pose serious health risks . For space administrations like NASA, a major goal is to identify these risks to hopefully help lessen them. 

That was a major theme during NASA’s Spaceflight for Everybody Virtual Symposium in November, a virtual symposium dedicated to discussing current knowledge and research efforts around the impact of spaceflight on human health. During a panel discussion titled “Human Health Risks in the Development of Future Programs” on Nov. 9, NASA scientists discussed these risks and how they are using existing knowledge to plan future missions. 

Each panelist emphasized that the health risks presented by space travel are complex and multifaceted and that all types of risks should be considered closely when planning future missions. 

Related:  Space travel can seriously change your brain  

Five types of risk

When discussing the risks presented by living in space and space travel, there are five main types, the scientists outlined in the presentation. 

Two types of risk, radiation and altered gravity, come simply from being in space, they said. Research has shown that both can have major negative effects on the body, and even the brain . Others, like isolation and confinement as well as being in a hostile closed environment, encompass risks posed by the living situations that are necessary in space, including risks to both mental and physical health. 

Then, there are the risks presented simply by being a long way from Earth. The farther humans get from the Earth, the riskier living in space becomes in almost every way. 

Get the Space.com Newsletter

Breaking space news, the latest updates on rocket launches, skywatching events and more!

Everything from fresh food to unexpired medication will be extremely difficult to make accessible with longer journeys farther away. On the International Space Station, astronauts aren’t too far from us, and we can routinely send supplies to the crews in orbit. But a mission to the moon or Mars would pose more problems. 

Communication delays would increase, and there would likely be communication blackouts, said Sharmi Watkins, assistant director for exploration in NASA’s Human Health and Performance Directorate who served as a panelist for this discussion.   She said it would also take longer to get back to Earth if there was a medical emergency. 

"We're not going to measure it in hours, but rather in days, in the case of the moon, and potentially weeks or months, when we start to think about Mars," said Watkins.

Steve Platts, the chief scientist in NASA’s human research program, broke down different levels of risk in space and discussed how NASA uses a "phased approach" when it comes to research on human health. In this approach, initial "phases" include research on the health effects of being in space has also been done in simulated conditions on Earth, from isolation experiments in Antarctica to radiation exposure at Brookhaven National Laboratory in Long Island, New York. Likewise, experiments on the space station will help us to prepare for risk on the moon and Mars — these later phases build on knowledge gained from simulations. 

"We do work on Earth, we do work on low earth orbit and then we'll be doing lunar missions, all to help us get to Mars," Platts said. 

— Deep-space radiation could cause have big impacts on the brain, mouse experiment shows

— Without gravity, the fluid around an astronaut's brain moves in weird ways

— Long space missions can change astronaut brain structure and function

Still, no matter how much we may prepare on Earth, every space mission comes with risk, so NASA has set health standards to minimize this risk for astronauts. 

NASA has over 800 health standards that they’ve developed based on current research. These standards describe everything from how much space astronauts should have in a spacecraft to how much muscle and bone loss an astronaut can experience without being seriously harmed. These standards also include levels of physical fitness and health the astronauts need to meet before going into space. All of NASA’s health standards for astronauts are available online . 

A mission can impact astronauts’ health, but it also works the other way — health troubles with astronauts could impact a mission if they aren’t able to perform mission tasks adequately, said Mary Van Baalen, acting director of human system risk management at NASA and the panel’s moderator. She emphasized the complex interplay between these two types of impacts, both of which NASA scientists must keep in mind when planning missions. 

"Space travel is an inherently risky endeavor," she said. "And the nature of human risk is complex."

You can watch the full recording of the panel discussion and other talks from the symposium here . 

Follow us on Twitter @Spacedotcom or Facebook.

Join our Space Forums  to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at:  [email protected].

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: [email protected].

Rebecca Sohn is a freelance science writer. She writes about a variety of science, health and environmental topics, and is particularly interested in how science impacts people's lives. She has been an intern at CalMatters and STAT, as well as a science fellow at Mashable. Rebecca, a native of the Boston area, studied English literature and minored in music at Skidmore College in Upstate New York and later studied science journalism at New York University. 

SpaceX's Falcon 9 rocket can return to flight, FAA says

'Deadpool & Wolverine' has a sneaky Canadarm robot arm cameo at the end of time — but blink and you'll miss it

'A lot has changed': NOAA is rewriting the book on how to rank solar storms

Most Popular

• 2 Satellites are making the night sky brighter — as a launch site, New Zealand has a duty to combat light pollution
• 3 Stick to the shade in new extended 'Dune: Awakening' gameplay trailer (video)
• 4 'Unbreakable' quantum communication closer to reality thanks to new, exceptionally bright photons
• 5 Star-packed Triangulum Galaxy shines in new Hubble Telescope image

Human Health during Space Travel: State-of-the-Art Review

Affiliations.

• 1 Department of Medicine and Center for Space Medicine, Section of Cardiology, Baylor College of Medicine, Houston, TX 77030, USA.
• 2 Translational Research Institute for Space Health, Houston, TX 77030, USA.
• 3 Department of Cardiovascular Diseases, New York University School of Medicine, New York, NY 10016, USA.
• 4 Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.
• 5 Flight Medicine, NASA Johnson Space Center, Houston, TX 77058, USA.
• 6 Department of Emergency Medicine and Center for Space Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
• 7 Department of Neurology, Center for Space Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
• 8 KBR, Houston, TX 77002, USA.
• 9 Department of Dermatology, Baylor College of Medicine, Houston, TX 77030, USA.
• 10 Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
• 11 InnovaSpace, London SE28 0LZ, UK.
• 12 Office of the Chief Health and Medical Officer, NASA, Washington, DC 20546, USA.
• 13 Microgen Laboratories, La Marque, TX 77568, USA.
• 14 Department of Surgery and Critical Care Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada.
• 15 Florida Institute for Human and Machine Cognition, Pensacola, FL 32502, USA.
• 16 Division of Biomedical Research and Environmental Sciences, NASA Lyndon B. Johnson Space Center, Houston, TX 77058, USA.
• 17 Department of Ophthalmology, University of Texas Medical Branch School of Medicine, Galveston, TX 77555, USA.
• 18 Department of Ophthalmology, Blanton Eye Institute, Houston Methodist Hospital, Houston, TX 77030, USA.
• 19 Department of Ophthalmology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
• 20 Department of Ophthalmology, Texas A and M College of Medicine, College Station, TX 77807, USA.
• 21 Department of Ophthalmology, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA.
• 22 Departments of Ophthalmology, Neurology, and Neurosurgery, Weill Cornell Medicine, New York, NY 10021, USA.
• 23 National Aeronautics and Space Administration (NASA) Johnson Space Center, Human Health and Performance Directorate, Houston, TX 77058, USA.
• PMID: 36611835
• PMCID: PMC9818606
• DOI: 10.3390/cells12010040

The field of human space travel is in the midst of a dramatic revolution. Upcoming missions are looking to push the boundaries of space travel, with plans to travel for longer distances and durations than ever before. Both the National Aeronautics and Space Administration (NASA) and several commercial space companies (e.g., Blue Origin, SpaceX, Virgin Galactic) have already started the process of preparing for long-distance, long-duration space exploration and currently plan to explore inner solar planets (e.g., Mars) by the 2030s. With the emergence of space tourism, space travel has materialized as a potential new, exciting frontier of business, hospitality, medicine, and technology in the coming years. However, current evidence regarding human health in space is very limited, particularly pertaining to short-term and long-term space travel. This review synthesizes developments across the continuum of space health including prior studies and unpublished data from NASA related to each individual organ system, and medical screening prior to space travel. We categorized the extraterrestrial environment into exogenous (e.g., space radiation and microgravity) and endogenous processes (e.g., alteration of humans' natural circadian rhythm and mental health due to confinement, isolation, immobilization, and lack of social interaction) and their various effects on human health. The aim of this review is to explore the potential health challenges associated with space travel and how they may be overcome in order to enable new paradigms for space health, as well as the use of emerging Artificial Intelligence based (AI) technology to propel future space health research.

Keywords: human health; microgravity; space exploration; space mission; space radiation; space travel.

Publication types

• Artificial Intelligence
• Circadian Rhythm
• Extraterrestrial Environment
• Space Flight*
• Weightlessness*

Grants and funding

March 22, 2023

Health Research Is Needed Now before Sending Civilians to Space

Now is the time to protect the health and safety of civilians who will be traveling, living and working in the dangerous environment of space

By Michael Marge

Blue Origin’s New Shepard lifts off from the Launch Site One launch pad carrying Good Morning America co-anchor Michael Strahan, Laura Shepard Churchley, daughter of astronaut Alan Shepard, and four other civilians on December 11, 2021 near Van Horn, Texas. The six are riding aboard mission NS-19, the third human spaceflight for the company which is owned by Amazon founder Jeff Bezos.

Mario Tama/Getty Images

Within decades, hundreds and perhaps thousands of average civilians will travel, live and work in space . Along with their space suits, they will bring with them their illnesses, chronic health problems and disabilities.

That changes the space story because until recently, career astronauts have been the only travelers in space, aside from the infrequent space tourist . But now that new space businesses are launching , the travelers and workers will be mostly civilians.

This civilian move into space has already started. Ticket-buying or privately funded passengers have traveled into suborbital space, 50 to 60 miles above Earth, during the past couple of years, courtesy of “New Space” firms Blue Origin and Virgin Galactic. In September 2021, billionaire Jared Isaacman rented Elon Musk’s Crew Dragon Resilience spaceship to carry him and three other civilians on a three-day journey around the Earth. Even without scientific evidence about health risks of such travel, Isaacman and Musk are willing to push the envelope further: They plan another flight this year called Polaris Dawn that would carry a private crew of four to the highest Earth orbit ever flown; the flight will include a spacewalk, one of space’s most hazardous endeavors. In addition, NASA has awarded incentive grants to three space corporations to build commercial orbital platforms that will start operating by the end of this decade. These space stations will be occupied by civilians as tourists and employees.

On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing . By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

We need to go the extra mile to protect civilians if they are to travel, live and work in space.

NASA’s reports on astronauts before, during and after extended space travel and habitation make this clear : astronauts face chronic motion sickness, neurological disorders, cardiovascular problems, increased risk for blood clotting and vision problems, as well as increased risks of cancer, muscle atrophy and bone loss. That’s despite their excellent health, physical and mental fitness, and years of training. As astronauts, they are fully aware of these risks and willing to take them. As former astronaut and now Senator Mark Kelly once said, “Being an astronaut is a high-risk job.” But average civilians in space should not take such risks, which for them are even more real.

In 2022, the CDC reported that within the U.S. population six in 10 adults have chronic disease , and four in 10 have two or more chronic diseases. Also, one in four have disabilities . These health conditions add a new and challenging dimension to space hazards on the human body. What we have learned from NASA is that the health profiles of astronauts and the health profiles of civilians are notably different.

To get ahead of this problem, a landmark scientific meeting was hosted in 2021 by the Commercial Spaceflight Federation (CSF) with the blessings of the National Space Council. Intended to develop the first ever “Human Research Program for Civilians in the Commercialization of Space,” a workshop of 100 experts, which I co-chaired, identified high-priority human research projects to safeguard civilians in space.

Unfortunately, some of the commercial space companies behind the health research program now appear uninterested. Why the turnaround? We can only speculate, but a host of answers suggest themselves, starting with the space industry hoping to retain a 2004 decision by Congress that imposed a moratorium on new safety regulations on human spaceflight , in the absence of death, serious injury or close call ; this “learning period,” which has been extended several times, gives the industry considerable leeway to experiment with humans. Second, these space companies compete with one another and are in a hurry to realize breakthroughs for their own business without slowing down for safety research. Third, some of the leaders in these companies challenge the cautions about the fragility of civilians in space. They argue that the hazards will have minor or short-term health impact. SpaceX CEO Elon Musk referred to the Inspiration4 spaceflight as “an intense roller coaster ride,” and added that anyone who can tolerate that “should be fine for flying on Dragon,” Musk’s spaceship. Some in the industry prefer to place average civilians in spaceflight, study them during and after flight and then examine ways to protect civilians in future flights. This risk-ridden exploratory approach to discovery should be discouraged.  It returns us to the days of the Wright brothers (who had multiple crashes and the first air passenger death ), where discovery occurs by risking calamity. 

If there is a catastrophic event where civilians become seriously ill, injured or die, only then will we wake up to the proposition that humans in space should travel without harm. Only then will we realize that the best approach is to conduct an unbiased, objective, large-scale, scientific human research program against all the known risks of space travel. 

But given today’s space-race realities, here’s a compromise: While space companies prosper under the moratorium, let them send civilians into space only after each one has undergone a thorough physical, mental and performance examination and preparatory training comparable to what is required of NASA’s career astronauts. Each company should publicize its preflight health and performance testing and training program. In addition, the space industry should publicly support the human research program it originally endorsed. Taking these steps would send civilians into space in the coming months and years in a responsible and safe manner. It would benefit the industry, assure public trust, and help protect civilians in space.

Even without industry support, we need health research now to protect future civilians in space, under the Federal Aviation Administration’s Office of Space Transportation (AST), Federal Aviation Agency. The AST has the experience, the mission, expertise and organizational setup to do an exceptional job.

The time to act is now by asking the Biden administration and Congress to fund a program of human research for civilians in space before it is too late, and we learn once more that “guinea pig” discoveries are rarely happy ones.

This is an opinion and analysis article, and the views expressed by the author or authors are not necessarily those of  Scientific American.

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

• View all journals
• My Account Login
• Explore content
• About the journal
• Publish with us
• Sign up for alerts
• Review Article
• Open access
• Published: 05 November 2020

Red risks for a journey to the red planet: The highest priority human health risks for a mission to Mars

• Zarana S. Patel   ORCID: orcid.org/0000-0003-0996-6381 1 , 2 ,
• Tyson J. Brunstetter 3 ,
• William J. Tarver 2 ,
• Alexandra M. Whitmire 2 ,
• Sara R. Zwart 2 , 4 ,
• Scott M. Smith 2 &
• Janice L. Huff   ORCID: orcid.org/0000-0003-4236-7698 5  

npj Microgravity volume  6 , Article number:  33 ( 2020 ) Cite this article

96k Accesses

165 Citations

360 Altmetric

Metrics details

• Cardiovascular diseases
• Eye diseases
• Neurological disorders
• Psychiatric disorders

NASA’s plans for space exploration include a return to the Moon to stay—boots back on the lunar surface with an orbital outpost. This station will be a launch point for voyages to destinations further away in our solar system, including journeys to the red planet Mars. To ensure success of these missions, health and performance risks associated with the unique hazards of spaceflight must be adequately controlled. These hazards—space radiation, altered gravity fields, isolation and confinement, closed environments, and distance from Earth—are linked with over 30 human health risks as documented by NASA’s Human Research Program. The programmatic goal is to develop the tools and technologies to adequately mitigate, control, or accept these risks. The risks ranked as “red” have the highest priority based on both the likelihood of occurrence and the severity of their impact on human health, performance in mission, and long-term quality of life. These include: (1) space radiation health effects of cancer, cardiovascular disease, and cognitive decrements (2) Spaceflight-Associated Neuro-ocular Syndrome (3) behavioral health and performance decrements, and (4) inadequate food and nutrition. Evaluation of the hazards and risks in terms of the space exposome—the total sum of spaceflight and lifetime exposures and how they relate to genetics and determine the whole-body outcome—will provide a comprehensive picture of risk profiles for individual astronauts. In this review, we provide a primer on these “red” risks for the research community. The aim is to inform the development of studies and projects with high potential for generating both new knowledge and technologies to assist with mitigating multisystem risks to crew health during exploratory missions.

Similar content being viewed by others

Selected discoveries from human research in space that are relevant to human health on Earth

Molecular and physiological changes in the SpaceX Inspiration4 civilian crew

Impact of diet on human nutrition, immune response, gut microbiome, and cognition in an isolated and confined mission environment

Introduction.

Spaceflight is a dangerous and demanding endeavor with unique hazards and technical challenges. Ensuring the overall safety of the crew—their physical and mental health and well-being—are vital for mission success. These are large challenges that are further amplified as exploration campaigns extend to greater distances into our solar system and for longer durations. The major health hazards of spaceflight include higher levels of damaging radiation, altered gravity fields, long periods of isolation and confinement, a closed and potentially hostile living environment, and the stress associated with being a long distance from mother Earth. Each of these threats is associated with its own set of physiological and performance risks to the crew (Fig. 1a ) that must be adequately characterized and sufficiently mitigated. Crews do not experience these stressors independently, so it is important to also consider their combined impact on human physiology and performance. This “space exposome” is a unifying framework that reflects the interaction of all the environmental impacts on the human body (Fig. 1b ) and, when combined with individual genetics, will shape the outcomes of space travel on the human system 1 , 2 .

a The key threats to human health and performance associated with spaceflight are radiation, altered gravity fields, hostile and closed environments, distance from Earth, and isolation and confinement. From these five hazards stem the health and performance risks studied by NASA’s Human Research Program. b The space exposome considers the summation of an individual’s environmental exposures and their interaction with individual factors such as age, sex, genomics, etc. - these interactions are ultimately responsible for risks to the human system. Images used in this figure are courtesy of NASA.

The NASA Human Research Program (HRP) aims to develop and provide the knowledge base, technologies, and countermeasure strategies that will permit safe and successful human spaceflight. With agency resources and planning directed toward extended missions both within low Earth orbit (LEO) and outside LEO (including cis-lunar space, lunar surface operations, a lunar outpost, and exploration of Mars) 3 , HRP research and development efforts are focused on mitigation of over 30 categories of health risks relevant to these missions. The HRP’s current research strategy, portfolio, and evidence base are described in the HRP Integrated Research Plan (IRP) and are available online in the Human Research Roadmap, a managed tool used to convey these plans ( https://humanresearchroadmap.nasa.gov/ ). To determine research priorities, NASA uses an evidence-based risk approach to assess the likelihood and consequence (LxC), which gauges the level of each risk for a set of standard design reference missions (Fig. 2 ) 4 . Risks are assigned a rating for their potential to impact in-mission crew health and performance and for their potential to impact long-term health outcomes and quality of life. “Red” risks are those that are considered the highest priority due to their greatest likelihood of occurrence and their association with the most significant risks to crew health and performance for a given design reference mission (DRM). Risks rated “yellow” are considered medium level risks and are either accepted due to a very low probability of occurrence, require in-mission monitoring to be accepted, or require refinement of standards or mitigation strategies in order to be accepted. Risks rated “green” are considered sufficiently controlled either due to lower likelihood and consequence or because the current knowledge base provides sufficient mitigation strategies to control the risk to an acceptable level for that DRM. Milestones and planned program deliverables intended to move a risk rating to an acceptable, controlled level are detailed in a format known as the path to risk reduction (PRR) and are developed for each of the identified risks. The most recent IRP and PRR documents are useful resources for investigators during the development of relevant research approaches and proposals intended for submission to NASA HRP research announcements ( https://humanresearchroadmap.nasa.gov/Documents/IRP_Rev-Current.pdf ).

NASA uses an evidence-based approach to assess likelihood and consequence for each documented human system risk. The matrix used for classifying and prioritizing human system risks has two sets of consequences—the left side shows consequences for in-mission risks while the right side is used to evaluate long-term health consequences (Romero and Francisco) 4 .

This work reviews HRP-defined high priority “red” risks for crew health on exploration missions: (1) space radiation health effects that include cancer, cardiovascular disease, and cognitive decrements (2) Spaceflight-Associated Neuro-ocular Syndrome (3) behavioral health and performance decrements, and (4) inadequate food and nutrition. The approaches used to address these risks are described with the aim of informing potential NASA proposers on the challenges and high priority risks to crew health and performance present in the spaceflight environment. This should serve as a primer to help individual proposers develop projects with high potential for generating both new knowledge and technology to assist with mitigating risks to crew health during exploratory missions.

Space radiation health risks

Outside of the Earth’s protective magnetosphere, crews are exposed to pervasive, low dose-rate galactic cosmic rays (GCR) and to intermittent solar particle events (SPEs) 5 . Exposures from GCR are from high charge (Z) and energy (HZE) ions, high-energy protons, and secondary protons, neutrons, and fragments produced by interactions with spacecraft shielding and human tissues. The main components of an SPE are low-to-medium energy protons. In LEO, the exposures are from GCR modulated by the Earth’s magnetic field and from trapped protons in the South Atlantic Anomaly. The absorbed doses for crews on the International Space Station (ISS) on 6- to 12-month missions range from ~30 to 120 mGy. Outside of LEO, without the protection offered by the Earth’s magnetosphere, absorbed radiation doses will be significantly higher. Estimates for a 1 year stay on the lunar surface range from 100 to 120 mGy, and 300 to 450 mGy for an ~3-year Mars mission (transit and surface stay) 6 . The exact dose a crewmember will receive is highly dependent on exact parameters of a given mission, such as detailed vehicle and habitat designs, and mission location and duration 7 . Time in the solar cycle is also a large factor contributing to crew exposure, with highest GCR exposure occurring during periods of minimum solar activity. The lowest GCR exposures occur during periods of maximum solar activity when the heightened magnetic activity of the Sun diverts some cosmic rays; however, during maximum solar activity, the probability of an SPE is higher 8 , 9 . SPEs, which vary in the magnitude and frequency, will obviously also contribute to total mission doses so it is important to note that total mission exposures are only estimates. Further information on the space radiation environment that astronauts will experience is discussed in Simonsen et al. 5 and Durante and Cucinotta 10 .

An important consideration for risk assessment is that the types of radiation encountered in space are very different from the types of radiation exposure we are familiar with here on Earth. HZE ions, although a small fraction of the overall GCR spectrum compared to protons, are more biologically damaging. They differ from terrestrial forms of radiation, such as X-rays and gamma-rays, in both the amount (dose) of exposure as well as in the patterns of DNA double-strand breaks and oxidative damage that they impart as they traverse through tissue and cells (Fig. 3 ) 5 . The highly energetic HZE particles produce complex DNA lesions with clustered double-stranded and single-stranded DNA breaks that are difficult to repair. This damage leads to distinct cellular behavior and intracellular signaling patterns that may be associated with altered disease outcomes compared to those for terrestrial sources of radiation 11 , 12 , 13 . As an example, persistently high levels of oxidative damage are observed in the intestine from mice examined 1 year after exposure to 56 Fe-ion radiation compared to gamma radiation and unirradiated controls 14 , 15 . The higher levels of residual oxidative damage in HZE ion-irradiated tissue is significant because of the association of oxidative stress and damage with the etiology of many human diseases, including cancer, cardiovascular and late neurodegenerative disorders. These types of alterations are believed to contribute to the higher biological effectiveness of HZE particles 10 , 11 .

a HZE ions produce dense ionization along the particle track as they traverse a tissue and impart distinct patterns of DNA damage compared to terrestrial radiation such as X-rays. γH2AX foci (green) illuminate distinct patterns of DNA double-strand breaks in nuclei of human fibroblast cells after exposure to b gamma-rays, with diffuse damage, and c HZE ions with single tracks. Image credits: NASA ( a ) and Cucinotta and Durante 97 ( b and c ).

Within the HRP, the Space Radiation Element (SRE) has developed a research strategy involving both vertical translation and horizontal integration, as well as products focused on mitigating space radiation risks across all phases of a mission. Vertical translation involves the integration of benchtop research with preclinical studies and clinical data. Horizontal integration involves a multidisciplinary approach that includes a range of expertize from physicians to clinicians, epidemiologists to computational modelers 16 . The suite of tools includes computational models of the space radiation environment, mission design tools, models for risk projection, and tools and technologies for accurate simulation of the space radiation environment for radiobiology investigations. Ongoing research is focused on radiation quality, age, sex, and healthy worker effects, medical countermeasures to reduce or eliminate space radiation health risks, understanding the complex nature of individual sensitivity, identification and validation of biomarkers (translational, surrogate, predictive, etc.) and integration of personalized risk assessment and mitigation approaches. Owing to the lack of human data for heavy ion exposure on Earth and the complications of obtaining reliable data for space radiation health effects from flight studies, SRE conducts research at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory. The NSRL is a ground-based analog for space radiation, where a beamline and associated experimental facilities are dedicated to the radiobiology and physics of a range of ions from proton and helium ions to the typical GCR ions such as carbon, silicon, titanium, oxygen, and iron 5 , 17 , 18 .

Radiation carcinogenesis

Central evidence for association between radiation exposure and the development of cancer and other non-cancer health effects comes from epidemiological studies of humans exposed to radiation 19 , 20 , 21 , 22 . Scaling factors are used by NASA and other space agencies in the analysis of cancer (and other risks) to account for differences between terrestrial radiation exposures and cosmic radiation exposures 23 . The risk of radiation carcinogenesis is considered a “red” risk for exploration-class missions due to both the high likelihood of occurrence, as well as the high potential for detrimental impact on both quality of life and disease-free survival post flight. The major cancers of concern are epithelial in origin (particularly cancers of the lung, breast, stomach, colon, and bladder), as well as leukemias ( https://humanresearchroadmap.nasa.gov/Evidence/reports/Cancer.pdf ). Owing to the lack of human epidemiology directly relevant to the types of radiation found in space, current research utilizes a translational approach that incorporates rodent and advanced human cell-based model systems exposed to space radiation simulants along with comparison of molecular pathways across these systems to the human.

A key question that impacts risk assessment and mitigation is how HZE tumors compare to either radiogenic tumors induced by ground-based radiation or spontaneous tumors. As a unifying concept, NASA studies have sought to examine how space radiation exposure modifies the key genetic and epigenetic modifications noted as the hallmarks of cancer (Fig. 4 ) 24 , 25 , 26 , 27 . This approach provides data for development of translational scaling factors (relative biological effectiveness values, quality factors, dose-rate effectiveness factor) to relate the biological effects of space radiation to effects from similar exposures to ground-based gamma- and X-rays and extrapolation of results to large human epidemiology cohorts. It also supports acquisition of mechanistic information required for successful identification and implementation of medical countermeasure strategies to lower this risk to an acceptable posture for space exploration, and it is relevant for the future development of biologically based dose-response models and integrated systems biology approaches 25 . Cancer is a long-term health risk and although it is rated as “red”, most research in this area is currently delayed, as HRP research priorities focus on in-mission risks.

Shown are the enabling characteristics and possible mechanisms of radiation damage that lead to these changes observed in all human tumors. (Adapted from Hanahanand Weinberg) 24 .

Risk of cardiovascular disease and other degenerative tissue effects from radiation exposure and secondary spaceflight stressors

A large number of degenerative tissue (non-cancer) adverse health outcomes are associated with terrestrial radiation exposure, including cardiovascular and cerebrovascular diseases, cataracts, digestive and endocrine disorders, immune system decrements, and respiratory dysfunction ( https://humanresearchroadmap.nasa.gov/Evidence/other/Degen.pdf ). For cardiovascular disease (CVD), a majority of the evidence comes from radiotherapy cohorts receiving high-dose mediastinal exposures that are associated with an increased risk for heart attack and stroke 28 . Recent evidence shows risk at lower doses (<0.5 Gy), with an estimated latency of 10 years or more 29 , 30 , 31 . For a Mars mission, preliminary estimates suggest that circulatory disease risk may increase the risk of exposure induced death by ~40% compared to cancer alone 32 . NASA is also concerned about in-flight risks to the cardiovascular system ( https://humanresearchroadmap.nasa.gov/Evidence/other/Arrhythmia.pdf ), when considering the combined effects of radiation exposure and other spaceflight hazards (Fig. 5 ) 33 . The Space Radiation Element is focused on accumulating data specific to the space radiation environment to characterize and quantify the magnitude of the degenerative disease risks. The current efforts are on establishing dose thresholds, understanding the impact of dose-rate and radiation quality effects, uncovering mechanisms and pathways of radiation-associated cardiovascular and cerebrovascular diseases, and subsequent risk modeling for astronauts. Uncovering the mechanistic underpinnings governing disease processes supports the development of specific diagnostic and therapeutic approaches, is a necessary step in the translation of insights from animal models to humans, and is the basis of personalized medicine approaches.

In blue are the known risk factors for CVD and in black are the other spaceflight stressors that may also contribute to disease development. Image used in this figure is courtesy of NASA.

This information will provide a means to reduce the uncertainty in current permissible exposure limits (PELs), quantify the impact to disease-free survival years, and determine if additional protection or mitigation strategies are required. The research portfolio includes evaluation of current clinical standard-of-care biomarkers for their relevance as surrogate endpoints for radiation-induced disease outcomes. Studies are also addressing the possible role of chronic inflammation and increased oxidative stress in the etiology of radiation-induced CVD, as well as identification of key events in disease pathways, like endothelial dysfunction, that will guide the most effective medical countermeasures. Products include validated space radiation PELs, models to quantify the risk of CVD for the astronaut cohort, and countermeasures and evidence to inform development of appropriate recommendations to clinical guidelines for diagnosis and mitigation of this risk.

Elucidating the role that radiation plays in degenerative disease risks is problematic because multiple factors, including lifestyle and genetic influences, are believed to play a major role in the etiology of these diseases. This confounds epidemiological analyses, making it difficult to detect significant differences from background disease without a large study population 34 . This issue is especially significant in astronaut cohorts because those studies have small sample sizes 35 . There is also a general lack of experimental data that specifically addresses the role of radiation at low, space-relevant doses 36 . Selection of experimental models needs to be carefully considered and planned to ensure that the cardiovascular disease mechanisms and study endpoints are clinically relevant and translatable to humans 37 , 38 . Combined approaches using data from wildtype and genetically modified animal models with accelerated disease development will likely be necessary to elucidate mechanisms and generate the body of knowledge required for development of accurate permissible exposure limits, risk assessment models, and to develop effective mitigation approaches.

Risk of acute (in-flight) and late CNS effects from space radiation exposure

The possibility of acute (in-flight) and late risks to the central nervous system (CNS) from GCR and SPEs are concerns for human exploration of space ( https://humanresearchroadmap.nasa.gov/Evidence/reports/CNS.pdf ). Acute CNS risks may include altered neurocognitive function, impaired motor function, and neurobehavioral changes, all of which may affect human health and performance during a mission. Late CNS risks may include neurological disorders such as Alzheimer’s disease, dementia, or accelerated aging. Detrimental CNS changes from radiation exposure are observed in humans treated with high doses of gamma-rays or proton beams and are supported by a large body of experimental evidence showing neurocognitive and behavioral effects in animal models exposed to lower doses of HZE ions. Rodent studies conducted with HZE ions at low, mission-relevant doses and time frames show a variety of structural and functional alterations to neurons and neural circuits with associated performance deficits 39 , 40 , 41 , 42 , 43 , 44 . Fig. 6 shows an example of changes in dendritic spine density following HZE ion radiation. However, the significance and relationship of these results to adverse outcomes in astronauts is unclear, as similar decrements are not seen with comparable doses of terrestrial radiation. Therefore, scaling to human epidemiology data, as is done for cancer and cardiovascular disease, is not possible. It is also important to note that to date, no radiation-associated clinically significant operational or long-term deficits have been identified in astronauts receiving similar doses via long-duration ISS missions. It is clear that further development of standardized translational models, research paradigms, and appropriate scaling approaches are required to determine significance in humans 45 , 46 . In addition, elucidation of how space radiation interacts with other mission hazards to impact neurocognitive and behavioral health and performance is critical to defining appropriate PELs and countermeasure strategies. The current research approach is a combined effort of SRE, the human factors and behavioral performance element, and the human health countermeasures element in support of an integrated CBS (CNS/behavioral medicine/sensorimotor) plan ( https://humanresearchroadmap.nasa.gov/Risks/risk.aspx?i=99 ). Further information on this risk area is presented below in the Behavioral Health and Performance section and can also be found at the Human Research Roadmap.

Representative digital images of 3D reconstructed dendritic segments (green) containing spines (red) in unirradiated (0 cGy) and irradiated (5 and 30 cGy) mice brains. Multiple comparisons show that total spine numbers (left bar chart) and spine density (right bar chart) are significantly reduced after exposure to 5 or 30 cGy of 16 O particles. Data are expressed as mean ± SEM. * P  < 0.05, ** P  < 0.01 versus control; ANOVA. Adapted from Parihar et al. 39 . Permission to reproduce open-source figure per the Creative Commons Attribution 4.0 International License. https://creativecommons.org/licenses/by/4.0 .

To summarize, the health risks posed by the omnipresent exposure to space radiation are significant and include the “red” risks of cancer, cardiovascular diseases, and cognitive and behavioral decrements. While research on the late health risk of cancer is currently delayed, research on the in-flight effects of radiation on the cardiovascular system and CNS within the context of the space exposome are considered the highest priority and are the focus of investigations. Major knowledge gaps include the effects of radiation quality, dose-rate, and translation from animal models to human systems and evaluation of the requirement for medical countermeasure approaches to reduce the risk.

Spaceflight-Associated Neuro-ocular Syndrome

The Risk of Spaceflight-Associated Neuro-ocular Syndrome (SANS), originally termed the Risk of Vision Impairment Intracranial Pressure (VIIP), was first discovered about 15 years ago. VIIP was the original name used because the syndrome most noticeably affects a crewmember’s eyes and vision, and its signs can appear like those of the terrestrial condition idiopathic intracranial hypertension (IIH; which is due to increased intracranial pressure). Over time, it was realized that the VIIP name required an update. Most notably, SANS is not associated with the classic symptoms of increased intracranial pressure in IIH (e.g., severe headaches, transient vision obscurations, double vision, pulsatile tinnitus), and it has never induced vision changes that meet the definition of vision impairment, as defined by the National Eye Institute. In 2017, VIIP was renamed to SANS, a term that welcomes additional pathogenesis theories and serves as a reminder that this syndrome could affect the CNS well beyond the retina and optic nerve.

SANS presents with an array of signs, as documented in the HRP Evidence Report ( https://humanresearchroadmap.nasa.gov/evidence/reports/SANS.pdf ). Primarily, these include edema (swelling) of the optic disc and retinal nerve fiber layer (RNFL), chorioretinal folds (wrinkles in the retina), globe flattening, and refractive error shifts 47 . Flight duration is thought to play a role in the pathogenesis of SANS, as nearly all cases have been diagnosed during or immediately after long-duration spaceflight (i.e., missions of 30 days duration or longer), although signs have been discovered as early as mission day 10 48 . Because of SANS, ocular data are nominally collected during ISS missions. For most ISS crewmembers, this testing includes optical coherence tomography (OCT), retinal imaging, visual acuity, a vision symptom questionnaire, Amsler grid, and ocular ultrasound (Fig. 7 ).

Image courtesy of NASA.

From a short-term perspective (e.g., a 6-month ISS deployment), SANS presents four main risks to crewmembers and their mission: optic disc edema (ODE), chorioretinal folds, shifts in refractive error, and globe flattening 49 . Approximately 69% of the US crewmembers on the ISS experience a > 20 µm increase in peripapillary retinal thickness in at least one eye, indicating the presence of ODE. With significant levels of ODE, a crewmember can experience an enlargement of his/her blind spots and a corresponding loss in visual function. To date, blind spots are uncommon and have not had an impact on mission performance.

If chorioretinal folds are severe enough and located near the fovea (the retina associated with central vision), a crewmember may experience visual distortions or reduced visual acuity that cannot be corrected with glasses or contact lenses, as noted in the SANS Evidence Report. Despite a prevalence of 15–20% in long-duration crewmembers, chorioretinal folds have not yet impacted astronauts’ visual performance during or after a mission. An on-orbit shift in refractive error is due to a shortening of the eye’s axial length (distance between the cornea and the fovea), and it occurs in about 16% of crewmembers during long-duration spaceflight. This risk is mitigated by providing deploying crewmembers with several pairs of “Space Anticipation Glasses” (or contact lenses) of varying power. On-orbit, the crewmember can then select the appropriate lenses to restore best-corrected visual acuity. Approximately 29% of long-duration crewmembers experience a posterior eyeball flattening, which is typically centered around the insertion of the optic nerve into the globe. Globe flattening can induce chorioretinal folds and shifts in refractive error, posing the respective risks described above.

From a longer-term perspective, SANS presents two main risks to crewmembers: ODE and chorioretinal folds. It is unknown if a multi-year spaceflight (e.g., a Mars mission) will be associated with a higher prevalence, duration, and/or severity of ODE compared to what has been experienced onboard the ISS. Since the retina and optic nerve are part of the CNS, if ODE is severe enough, the crewmember risks a permanent loss of optic nerve and RNFL tissue and thus, a permanent loss of visual function. It should be stressed that no SANS-related permanent loss of visual function has yet been discovered in any astronauts.

For choroidal folds, improvement generally occurs post-flight in affected crewmembers; however, significant folds can persist for 10 or more years after long-duration missions. Using MultiColor Imaging and autofluorescence capabilities of the latest OCT device, it was discovered recently that one crewmember’s longstanding (>5 years) post-flight choroidal folds have induced disruption to its overlying retinal pigment epithelium (RPE) 50 . The RPE is a monolayer of pigmented cells located between the vascular-rich choroid and the photoreceptor outer segments. This layer forms the posterior blood-brain barrier for the retina and is essential for maintaining the health of the posterior retina via the transport of nutrients and fluids, among other key functions. If the RPE is damaged, it could potentially lead to a degeneration of the local retina and progress to vision impairment.

Recent long-duration head-down tilt studies have shown potential for recreating SANS signs in terrestrial cohorts 51 . However, SANS is considered a pathology unique to spaceflight. In microgravity, fluid within the body is free to redistribute uniformly. This means that much of the fluid that normally pools in a person’s feet and legs due to gravity can transfer upward towards the head and cause a general congestion of the cerebral venous system. The central pathogenesis theories of SANS are based on these facts, but the actual cause(s) and pathophysiology of SANS are yet unknown 49 . The most publicized theory for SANS has been that cerebral spinal fluid outflow might be impeded, causing an overall increase in intracranial pressure (ICP) 47 , 52 . Other potential mechanisms (see Fig. 8 ) include cerebral venous congestion or altered folate-dependent 1-carbon metabolism via a cascade of mechanisms that may ultimately increase ICP or affect the response of the eye to fluid shifts 53 , 54 . Potential confounding variables for SANS pathogenesis include resistive exercise, high-sodium dietary intake, and high carbon dioxide levels.

Image created with BioRender.com.

Discovering patterns and trends in the SANS population has been difficult due to the relatively low number of crewmembers who have completed long-duration spaceflight. This is especially true for female astronauts. However, there is now enough evidence to state—emphatically—that SANS is not a male-only syndrome. OCT has been utilized onboard the ISS since late 2013, and it has revolutionized NASA’s ability to objectively detect and monitor SANS and build a high-resolution database of retinal and optic nerve head images. Through this technology, it has been recently discovered that that a majority of long-duration astronauts (including females) present with some level of ODE and engorgement of the choroidal vasculature 48 , 55 . The trends and patterns of these ocular anatomical changes may hold the key to deciphering the pathophysiology of SANS 48 , 55 .

Beginning in 2009 in response to SANS, all NASA crewmembers receive pre- and post-flight 3 Tesla magnetic resonance imaging of the brain and orbits. Based on these images, there is growing evidence that brain structural changes also occur during long-duration spaceflight. Most notably, a 10.7–14.6% ventricular enlargement (i.e., approximately a 2–3 ml increase) has been detected in astronauts and cosmonauts by multiple investigators 56 , 57 , 58 , 59 . On-orbit and post-flight cognitive testing have not revealed any systemic cognitive decrements associated with these anatomical changes. Moreover, additional research is required to determine if spaceflight-associated brain structural changes are related to ocular structural changes (i.e., SANS) or if the two are initiated by a common cause. Thus, until a relationship is established, SANS will be defined by ocular signs.

Future SANS medical operations, research, and surveillance will focus on: 1) determining the pathogenesis of the syndrome, 2) developing small-footprint diagnostic devices for expeditionary spaceflight, 3) establishing effective countermeasures, 4) monitoring for any long-term health consequences, and 5) discovering what factors make certain individuals more susceptible to developing the syndrome.

In summary, SANS is a top risk and priority to NASA and HRP. The primary SANS-related risk is ODE, due to the possibility of permanent vision impairment; however, choroidal folds also present a short- and long-term risk to astronaut vision. Shifts in refractive error are relatively common in long-duration missions, but crewmembers do not experience a loss of visual acuity if adequate correction is available. SANS affects female astronauts, not just males, although it is not yet known if SANS prevalence is equal between the sexes. There are no terrestrial pathologies identical to SANS, including IIH. Long-duration spaceflight is also associated with brain anatomical changes; however, it is not yet known whether these changes are related to SANS. Finally, the pathogenesis of SANS remains elusive; however, the main theories are related to increased intracranial pressure, ocular venous congestion, and individual anatomical/genetic variability.

Behavioral health and performance

The Risk of Adverse Cognitive and Behavioral Conditions and Psychiatric Disorders (BMed) focuses on characterizing and mitigating potential decrements in performance and psychological health resulting from multiple spaceflight hazards, including isolation and distance from earth. Spaceflight radiation is also recognized as contributing factor, particularly relative to a deep space planetary mission. The potential of additive or synergistic effects on the CNS resulting from simultaneous exposures to radiation, isolation and confinement, and prolonged weightlessness, is also of emerging concern ( https://humanresearchroadmap.nasa.gov/Risks/risk.aspx?i=99 ).

The official risk statement in the BMed Evidence Report notes, “ given the extended duration of future missions and the isolated, confined and extreme environments, there is a possibility that (a) adverse cognitive or behavioral conditions will occur affecting crew health and performance; and (b) mental disorders could develop should adverse behavioral conditions be undetected and unmitigated ” ( https://humanresearchroadmap.nasa.gov/Evidence/reports/BMED.pdf ). Primary outcomes for this risk include decrements in cognitive function, operational performance, and psychological and behavioral states, with the development of psychiatric disorders representing the least likely but one of the most consequential outcomes crew could experience in extended spaceflight. BMed is considered a “red” risk for planetary missions, given the long-duration of isolation, extended confinement, and exposure to additional stressors, including increased radiation exposure. The Human Factors and Behavioral Performance Element within HRP utilizes a research strategy that incorporates flight studies on astronauts, research in astronaut-like individuals and teams in ground analogs, and works with the Space Radiation Element to use animal models supporting research on combined spaceflight stressors.

While astronauts successfully accomplish their mission objectives and report very positive experiences living and working in space, some anecdotal accounts from current and past astronauts suggest that psychological adaptation in the long-duration spaceflight environment can be challenging. However, clinically significant operational decrements have not been documented to date, as noted in the BMed Evidence Report. Discrete events that have been documented include accounts of adverse responses to workload by Shuttle payload specialists, and descriptions of ‘hostile’ and ‘irritable’ crew in the 84-day Skylab 4 mission, as well as symptoms of depression reported on Mir by 2 of the 7 NASA astronauts.

Currently, potential stressors affiliated with missions to the ISS include extended periods of high workload and/or schedule shifting, physiological adaptation including fluid shifts caused by weightlessness and possibly, exposure to other environmental factors such as elevated carbon dioxide (see the BMed Evidence Report). While still physically isolated from home, the presence of the ISS in LEO facilitates a robust ground behavioral health and performance support team who offer services such as bi-weekly private psychological conferences and regular delivery of novel goods and surprises from home in crew care packages. Coupled with the relatively ample volume in the ISS, near-constant real-time communication with Earth, new crewmembers rotating periodically throughout missions, and relatively low levels of radiation exposure, —it is expected that behavioral challenges experienced today do not represent those that future crews will face during exploration missions.

Nevertheless, the few completed behavioral studies on the ISS suggest that subjective perceptions of stress increase over time for some crewmembers, as shown by an in-flight study collecting subjective ratings of well-being and objective measures of fatigue 60 . Notably, it was found that astronaut ratings of sleep quality and sleep duration (also measured through visual analog scales) were found to be inversely related to ratings of stress. Another in-flight investigation seeking to characterize behavioral responses to spaceflight is the “Journals” study by Stuster 61 . This investigation provided a systematic approach to examining a rich set of qualitative data by evaluating astronaut journal entries for temporal patterns of across different behavioral states over the course of a mission (Fig. 9 ). Based on findings, some categories suggest temporal patterns while other categories of outcomes do not suggest a pattern relative to time, which may be due to no temporal relationship between outcomes and time, and/or various contextual factors within missions that negate the presence of such a relationship (e.g., visiting crew). An overall assessment by Stuster of negative comments relative to positive comments over time suggests evidence of a third quarter phenomenon in Adjustment alone, a category which reflects individual morale 61 .

Example bar graph showing distribution of journal entries related to general adjustment to the spaceflight enivronment during each quarter of an ISS mission 61 .

Other in-flight investigations support and expand upon contributors to increased stress on-orbit, including studies documenting reductions in sleep duration 62 , 63 and evaluation of crew responses to habitability and human factors during spaceflight 64 . While no studies have assessed potentially relevant mechanisms for behavioral or other reported symptoms, a recently completed investigation suggests neurostructural changes may be occurring in the spaceflight environment 56 . Magnetic resonance imaging scans were conducted on astronauts pre- and post-flight on both long-duration missions to the ISS or short-duration Shuttle missions. Assessments from a subgroup of participants ( n  = 12) showed a slight upward shift of the brain after all long-duration flights but not after short-duration flights ( n  = 6), and they also showed narrowing of cerebral spinal fluid spaces at the vertex after all long-duration flights ( n  = 6) and in 1 of 6 crew after short-duration flights. A retrospective analysis of free water volume in the frontal, temporal, and occipital lobes before versus after spaceflight suggests alterations in free water distribution 65 . Whether there is a functionally relevant outcome as a result of such changes remains to be determined. Hence, while certain aspects of the spaceflight environment have been shown to increase some behavioral responses (e.g., reduced sleep owing to workload), the direct role of spaceflight-specific factors (such as fluid shifts and weightlessness) on behavioral outcomes or functional performance has not yet been established.

Future long-duration missions will pose threats to behavioral health and performance, such as extreme confinement in a small volume and communication delays, that are distinct from what is currently experienced on missions to the ISS. Analog research is concurrently underway to help further characterize the likelihood and consequence of an adverse behavioral outcome, and the effectiveness of potential countermeasures. Ground analogs, such as the Human Exploration Research Analog (HERA) at NASA Johnson Space Center, provide a test bed where controlled studies of small teams for periods up to 45 days, can be implemented (Fig. 10 ). HERA can be used to provide scenarios and environments analogous to space (e.g., isolation and confinement, communication delays, space food, and daily tasks and schedules) to investigate their effects on behavioral health, human factors, exploration medical capabilities, and communication and autonomy. Research in locations such as Antarctica also offer a unique opportunity to conduct research in less controlled but higher fidelity conditions. In general, these studies show an increased risk in deleterious effects such as decreased mood and increased stress, and in some instances, psychiatric outcomes (see the BMed Evidence Report).

HERA is used to simulate environments and mission scenarios analogous to spaceflight to investigate a variety of behavioral and human factors issues. Images courtesy of NASA.

In 2014, Basner and colleagues 62 completed an assessment of crew health and performance in a 520-day mission at an isolation chamber in Moscow at the Institute for Biomedical Problems (IBMP). During this simulated mission to Mars, the crew of six completed behavioral questionnaires and additional testing weekly. One of six (20%) crew reported depressive symptoms based on the Beck Depression Inventory in 93% of mission weeks, which reached mild-to-moderate levels in >10% of mission weeks. Additional indications of changes in mood were observed via the Profile of Mood States. Additionally, two crewmembers who had the highest ratings of stress and physical exhaustion accounted for 85% of the perceived conflicts, and other crew demonstrated dysregulation in their circadian entrainment and sleep difficulties. Two of the six crewmembers reported no adverse behavioral symptoms during the missions 62 . Building on this work, the NASA HRP and the IBMP have ongoing studies in the SIRIUS project, a series of long-duration ground-analog missions for understanding the effects of isolation and confinement on human health and performance ( http://www.nasa.gov/analogs/nek/about ).

Finally, more recent research in the HERA analog at Johnson Space Center is underway to assess not only individual, psychiatric outcomes but also changes in team dynamics and team performance over time (Fig. 10 ). A recent publication reported that conceptual team performance (e.g., creativity) seems to decrease over time, while performance requiring cognitive function and coordinated action improved 66 . While results from additional team studies in HERA are currently under review, the Teams Risk Evidence Report ( https://humanresearchroadmap.nasa.gov/Evidence/reports/Team.pdf ) provides a thorough overview of the evidence surrounding team level outcomes.

In summary, evidence from spaceflight and spaceflight analogs suggests that the BMed Risk poses a high likelihood and high consequence risk for exploration. Given the possible synergistic effects of prolonged isolation and confinement, radiation exposure, and prolonged weightlessness, mitigating such enhanced risks faced by future crews are of highest priority to the NASA HRP.

Inadequate food and nutrition

Historically, nutrition has driven the success—and often the failure—of terrestrial exploration missions. For space explorers, nutrition provides indispensable sustenance, provides potential countermeasures to some of the negative effects of space travel on human physiology, and also presents a multifaceted risk to the health and safety of astronauts ( https://humanresearchroadmap.nasa.gov/Evidence/other/Nutrition-20150105.pdf ).

At a minimum, the need to prevent nutrient deficiencies is absolute. This was proven on voyages during the Age of Sail, where scurvy—caused by vitamin C deficiency— killed more sailors than all other causes of death. On a closed (or even semi-closed) food system, the risk of nutrient deficiency is increased. On ISS missions, arriving vehicles typically bring some fresh fruits and/or vegetables to the crew. While limited in volume and shelf-life, these likely provide a valuable source of nutrients and phytochemicals every month or two. One underlying concern is that availability of these foods may be mitigating nutrition issues of the nominal food system, and without this external source of nutrients on exploration-class missions, those issues will be more likely to surface.

As a cross-cutting science, nutrition interfaces with many, if not all, physiological systems, along with many of the elements associated with space exploration, including the spacecraft environment (Fig. 11 ). Thus, beyond the basics of preventing deficiency of specific nutrients, at best, nutrition can serve as a countermeasure to mitigate risks to other systems. Conversely, at worst, diet and nutrition can exacerbate risks to other physiological systems and crew health. For example, many of the diseases of concern as related to space exploration are nutritionally modifiable on Earth, including cancer, cardiovascular disease, osteoporosis, sarcopenia, and cataracts.

Many of the physiological systems and performance characteristics that are touched by nutrition are shown in white text, while the unique elements of spacecraft and space exploration are shown in red text.

The NASA Nutritional Biochemistry Laboratory approaches astronaut health with both operational and research efforts. These efforts aim to keep current crews healthy while working to understand and define optimal nutrition for future crews, to maximize performance and overall health while minimizing damaging effects of spaceflight exposure.

A Clinical Nutrition Assessment is conducted for ISS astronauts dating back to ISS Expedition 1 67 , 68 , which includes pre- and post-flight biochemical analyses conducted on blood and urine samples, along with in-flight monitoring of dietary intake and body mass. The biochemical assessments include a wide swath of nutritional indicators such as vitamins, minerals, proteins, hematology, bone markers, antioxidant markers, general chemistry, and renal stone risk. These data are reported to the flight surgeon soon after collection for use in the clinical care of the astronaut. Initial findings from the Clinical Nutritional Assessment protocol identified evidence of vitamin D deficiency, altered folate status, loss of body mass, increased kidney stone risk, and more 69 , 70 . These initial findings led to several research efforts (described below), including the Nutritional Status Assessment flight project, and research in the Antarctic on vitamin D supplementation 71 , 72 .

In addition to in-flight dietary intake monitoring, research to understand the impact and involvement of nutrition with other spaceflight risks such as bone loss and visual impairments, and interaction with exercise and spacecraft environment, are performed by the Nutrition Team using both flight and ground-analog research efforts. Tracking body mass is a very basic but nonetheless indispensable element of crew health 73 . Loss of body mass during spaceflight and in ground analogs of spaceflight is associated with exacerbated bone and muscle loss, cardiovascular degradation, increased oxidative stress, and more 70 , 73 , 74 . Historically, it was often assumed that some degree of body mass loss was to be expected, and that this was a typical part of adaptation to microgravity. Fluid loss is often assumed to be a key factor, but research has documented this to be a relatively small contributor, of approximately 1% of weight loss being fluid 74 , 75 . While on average, crewmembers on ISS missions have lost body mass over the course of flight, not all do 74 . Importantly, those that did not lose body mass managed to maintain bone mineral density (discussed below) 76 .

Bone loss has long been a concern for space travelers 77 , 78 , 79 , 80 , 81 . It has been shown that an increase in bone resorption was the likely culprit and that bone formation was largely unchanged in microgravity or ground analogs 77 , 78 , 79 . The search for a means to counteract this bone loss, and this hyper-resorptive state specifically, has been extensive. The potential for nutrition to mitigate this bone loss was identified early but studies of increasing intakes of calcium, or fluoride, or phosphate, were unsuccessful 74 , 77 , 79 , 82 , 83 , 84 .

Exercise provides a multisystem countermeasure, and heavy resistive exercise specifically provides for loading of bone to help mitigate weightlessness-induced bone loss.

In evaluating the data from astronauts using the first “interim” resistive exercise device (iRED) on ISS compared to a later, “advanced” resistive exercise device (ARED) (Fig. 12 ), it was quickly realized that exercise was not the only difference in these two groups of astronauts. ARED crews had better dietary intakes (as evidenced by maintenance of body mass) and better vitamin D status as a result of increased dose of supplementation and awareness of the importance of these supplements starting in 2006 76 . Bone mineral density was protected in these astronauts 76 , proving that diet and exercise are a powerful countermeasure combination. Follow-on evaluations showed similar results and further that the effects of microgravity exposure on bone health in men and women were similar 85 despite differences in pre-flight bone mass.

Sunita Williams exercising on the iRED ( a ), and on a later mission, Sandy Magnus exercises on the much improved ARED device ( b ). Images courtesy of NASA.

From a purely nutrition perspective, ISS and associated ground analog research has identified several specific dietary effects on bone health. Fish intake, likely secondary to omega-3 fatty acid intake, is beneficial for bone health 86 . Conversely, high intakes of dietary protein 87 , 88 , iron 89 and sodium 90 are detrimental to bone. The mechanism of the effect of protein and sodium on bone are likely similar, with both contributing to the acidogenic potential of the diet, leading to bone dissolution 91 , 92 . This effect was recently documented in a diet and bone health study on ISS, where the acidogenic potential of the diet correlated with post-flight bone losses 93 . The data from terrestrial research, along with the more limited spaceflight research, clearly identifies nutrition as important in maintenance of bone health and in the mitigation of bone loss. While initial evaluations of dietary quality and health are underway at NASA, much work remains to document the full potential of nutrition to mitigate bone loss and other disease processes in space travelers.

Another health risk with nutrition underpinnings is SANS, which was described earlier. When this issue first arose, an examination of data from the aforementioned ISS Nutrition project was conducted. This analysis revealed that affected crewmembers had significantly higher circulating concentrations of homocysteine and other one-carbon pathway metabolites when compared to non-cases and that these differences existed before flight 53 . Many potential confounding factors were ruled out, including: sex, kidney function, vitamin status, and coffee consumption, among others. After identifying differences in one-carbon biochemistry, the next logical step was to examine the genetics—single-nucleotide polymorphisms (SNPs)—involved in this pathway as possible causes of the biochemical differences, but perhaps also their association with the astronaut ocular pathologies. An initial study examined a small set of SNPs—five to be exact—and when the data were statistically modeled, it was found that B-vitamin status and genetics were significant predictors of many of the observed ophthalmic outcomes in astronauts 94 . Interestingly, the same SNPs identified in astronauts to be associated with ophthalmic changes after flight were associated with greater changes in total retina thickness after a strict head-down tilt with 0.5% CO 2 bed rest study 54 . A follow-on study is underway to evaluate a much broader look at one-carbon pathway and associated SNPs, potentially to help better characterize this relationship.

A hypothesis was developed to plausibly link these genetics and biochemical differences with these ophthalmic outcomes, as there is no existing literature regarding such a relationship. This multi-hit hypothesis posits that one-carbon pathway genetics is an indispensable factor, and that the combination with one or more other factors (e.g., fluid shifts, carbon dioxide, radiation, endocrine effects) lead to these pathologies. This has been detailed in a hypothesis paper 95 and in a recent review 96 . In brief, the hypothesis is that genetics and B-vitamin status contribute to endothelial dysfunction, as folate (and other B-vitamins) play critical roles in nitric oxide synthesis and endothelial function. A disruption in nitric oxide synthesis can also lead to an activation of matrix metalloproteinase activation, increasing the turnover and breakdown of structural elements of the sclera, altering retinal elasticity and increasing susceptibility to fluid shifts to induce ophthalmic pathologies like optic disc edema and choroidal folds 54 . This is likely exacerbated cerebrally due to limitations of transport of B-vitamins across the blood-brain barrier. In or around the orbit, endothelial dysfunction, oxidative stress, and potentially individual anatomical differences contribute to leaky blood vessels, and subsequent edema. This can impinge on cerebrospinal fluid drainage from the head, increasing those fluid pressures, which can impinge upon the optic nerve and eye itself, yielding the aforementioned ophthalmic pathologies. These are hypotheses proposed as starting points for further research. Given the irrefutable biochemical and genetic findings to date, this research should be a high priority to either prove or dismiss these as contributing factors in SANS to mitigate that “red” risk.

Another intriguing element from this research is that there is a clinical population that has many of the same characteristics of affected astronauts (or characteristics that they are purported to have), and that is women with polycystic ovary syndrome (PCOS) 95 , 96 . Women with PCOS have higher circulating homocysteine concentrations (as do their siblings and fathers), and also have cardiovascular pathology, including endothelial dysfunction. Studies are underway between NASA and physicians at the Mayo Clinic in Minnesota to evaluate this further. If validated, women with PCOS might represent an analog population for astronaut ocular issues, and research to counteract this could benefit both populations 87 . This research may lead to the identification of one-carbon pathway genetic influences on cardiovascular function in astronauts (and women with PCOS). This information will not be used in any sort of selection process, for several reasons, but as a means to identify countermeasures. Given the effects are intertwined with vitamin status, and likely represent higher individual vitamin requirements, targeted B-vitamin supplementation is the most obvious, and lowest risk, countermeasure that needs to be tested. There is tremendous potential for nutrition research to solve one of the key risks to human health on space exploration missions.

To summarize, nutrition is a cross-cutting field that has influence on virtually every system in the body. While we need to understand nutrition to avoid frank deficiencies, we need to understand how optimizing nutrition might also help mitigate other spaceflight-induced human health risks. Examples of this are myriad, ranging from effects of dietary intake on cognition, performance, and morale, inadequate intake on cardiovascular performance, excess nutrient intakes, leading to excess storage and increased oxidative stress, nutrient insufficiencies, leading to bone loss, insufficient fruit and vegetable intake on bone health, radiation protection, and cardiovascular health, to name a just few. Throughout history, nutrition has served, or failed, many a journey to explore. We need to dare to use and expand our twenty-first century knowledge of nutrition, uniting medical and scientific teams, to enable future exploration beyond LEO, while simultaneously benefitting humanity.

The NASA Human Research Program is focused on developing the tools and technologies needed to control the high priority “red” risks to an acceptable level—a great challenge as the risks do not exist in the vacuum of space as standalone entities. They are inherently interconnected and represent the intersection points where the five hazards of spaceflight overlap, and nature meets nurture. This is the space exposome: the total sum of spaceflight and lifetime exposures and how they relate to individual genetics and determine the whole-body outcome. The space exposome will be an important unifying concept as the hazards and risks of spaceflight are evaluated in a systems biology framework to fully uncover the emergent effects of the extraterrestrial experience on the human body. This framework will provide a path forward for mitigating detrimental health and performance outcomes that may stand in the way of successful, long-duration space travel, especially as NASA plans for a return to the Moon, to stay, and beyond to Mars.

Wild, C. P. The exposome: from concept to utility. Int. J. Epidemiol. 41 , 24–32 (2012).

Article   PubMed   Google Scholar  

Crucian, B. E. et al. Immune system dysregulation during spaceflight: potential countermeasures for deep space exploration missions. Front. Immunol. 9 , 1–21 (2018).

Article   CAS   Google Scholar  

Cassell, A. M. Forward to the Moon: NASA’s Strategic Plan for Human Exploration (NASA Ames Research Center ARC-E-DAA-TN73512, 2019).

Romero, E. & Francisco, D. The NASA human system risk mitigation process for space exploration. Acta Astronaut. 175 , 606–615 (2020).

Article   Google Scholar  

Simonsen, L. C., Slaba, T. C., Guida, P. & Rusek, A. NASA’s first ground-based Galactic Cosmic Ray Simulator: enabling a new era in space radiobiology research. PLOS Biol. 18 , e3000669 (2020).

Article   CAS   PubMed Central   PubMed   Google Scholar  

Norbury, J. W. et al. Galactic cosmic ray simulation at the NASA Space Radiation Laboratory. Life Sci. Space Res. (Amst.) 8 , 38–51 (2016).

NCRP. Report No. 183—Radiation Exposure in Space and the Potential for Central Nervous System Effects: Phase II . (National Council on Radiation Protection, 2019).

Slaba, T., Mertens, C. J. & Blattnig, S. R. Radiation Shielding Optimization on Mars . (NASA/TP–2013-217983, 2013).

Simonsen, L. C. & Nealy, J. E. Radiation Protection for Human Missions to the Moon and Mars . (NASA-TP-3079, 1991).

Durante, M. & Cucinotta, F. A. Heavy ion carcinogenesis and human space exploration. Nat. Rev. Cancer 8 , 465–472 (2008).

Article   CAS   PubMed   Google Scholar  

Li, M. et al. Health risks of space exploration: targeted and nontargeted oxidative injury by high-charge and high-energy particles. Antioxid. Redox Signal. 20 , 1501–1523 (2014).

Sridharan, D. M., Chappell, L. J., Whalen, M. K., Cucinotta, F. A. & Pluth, J. M. Defining the biological effectiveness of components of High-LET track structure. Radiat. Res. 184 , 105–119 (2015).

Rose, Li,Y. et al. Mutational signatures in tumours induced by high and low energy radiation in Trp53 deficient mice. Nat. Commun. 11 , 394 (2020).

Datta, K., Suman, S., Kallakury, B. V. S. & Fornace, A. J. Exposure to heavy ion radiation induces persistent oxidative stress in mouse intestine. PLoS ONE 7 , e42224 (2012).

Kumar, S., Suman, S., Fornace, A. J. & Datta, K. Space radiation triggers persistent stress response, increases senescent signaling, and decreases cell migration in mouse intestine. Proc. Natl Acad. Sci. USA 115 , E9832–E9841 (2018).

Article   CAS   PubMed   PubMed Central   Google Scholar  

National Academies of Sciences, Engineering, and Medicine of Sciences. A Midterm Assessment of Implementation of the Decadal Survey on Life and Physical Sciences Research at NASA . (The National Academies Press, 2018).

La Tessa, C., Sivertz, M., Chiang, I.-H., Lowenstein, D. & Rusek, A. Overview of the NASA space radiation laboratory. Life Sci. Space Res. (Amst.) 11 , 18–23 (2016).

Schimmerling, W. Genesis of the NASA space radiation laboratory. Life Sci. Space Res. (Amst.) 9 , 2–11 (2016).

Ozasa, K., Cullings, H. M., Ohishi, W., Hida, A. & Grant, E. J. Epidemiological studies of atomic bomb radiation at the radiation effects research foundation. Int. J. Radiat. Biol. 95 , 879–891 (2019).

Boice, J. D. et al. The past informs the future: an overview of the million worker study and the mallinckrodt chemical works cohort. Health Phys. 114 , 381–385 (2018).

Richardson, D. B. et al. Site-specific solid cancer mortality after exposure to ionizing radiation. Epidemiology 29 , 31–40 (2018).

Article   PubMed Central   PubMed   Google Scholar  

Kamiya, K. et al. Long-term effects of radiation exposure on health. Lancet 386 , 469–478 (2015).

Cucinotta, F. A., Kim, M.-H. Y. & Chappell, L. J. Space Radiation Cancer Risk Projections and Uncertainties–2012 . Vol. 186 (2013).

Hanahan, D. & Weinberg, R. A. Hallmarks of cancer: the next generation. Cell 144 , 646–674 (2011).

Barcellos-Hoff, M. H. et al. Concepts and challenges in cancer risk prediction for the space radiation environment. Life Sci. Space Res. (Amst.) 6 , 92–103 (2015).

Barcellos-Hoff, M. H. & Mao, J.-H. HZE radiation non-targeted effects on the microenvironment that mediate mammary carcinogenesis. Front. Oncol. 6 , 57 (2016).

Sridharan, D. M. et al. Understanding cancer development processes after HZE-particle exposure: roles of ROS, DNA damage repair and inflammation. Radiat. Res. 183 , 1–26 (2015).

Sylvester, C. B., Abe, J.-I., Patel, Z. S. & Grande-Allen, K. J. Radiation-induced cardiovascular disease: mechanisms and importance of linear energy transfer. Front. Cardiovasc. Med. 5 , 5 (2018).

Article   PubMed Central   CAS   PubMed   Google Scholar  

Darby, S. C. et al. Risk of ischemic heart disease in women after radiotherapy for breast cancer. N. Engl. J. Med. 368 , 987–998 (2013).

Little, M. P. et al. Systematic review and meta-analysis of circulatory disease from exposure to low-level ionizing radiation and estimates of potential population mortality risks. Environ. Health Perspect. 120 , 1503–1511 (2012).

ICRP. ICRP statement on tissue reactions and early and late effects of radiation in normal tissues and organs-threshold doses for tissue reactions in a radiation protection context. ICRP Publication 118. Ann. ICRP 41 , 1–322 (2012).

Google Scholar  

Cucinotta, F. A., Kim, M.-H. Y., Chappell, L. J. & Huff, J. L. How safe is safe enough? Radiation risk for a human mission to Mars. PLoS ONE 8 , e74988 (2013).

Hughson, R. L., Helm, A. & Durante, M. Heart in space: effect of the extraterrestrial environment on the cardiovascular system. Nat. Rev. Cardiol. 15 , 167–180 (2018).

Kreuzer, M. et al. Low-dose ionising radiation and cardiovascular diseases-Strategies for molecular epidemiological studies in Europe. Mutat. Res. Rev. Mutat. Res. 764 , 90–100 (2015).

Elgart, S. R. et al. Radiation exposure and mortality from cardiovascular disease and cancer in early NASA astronauts. Sci. Rep. 8 , 8480 (2018).

Boerma, M. An introduction to space radiation and its effects on the cardiovascular system. THREE , 1–12 (2016).

Camacho, P., Fan, H., Liu, Z. & He, J.-Q. Small mammalian animal models of heart disease. Am. J. Cardiovasc. Dis. 6 , 70–80 (2016).

CAS   PubMed Central   PubMed   Google Scholar  

Ko, K. A. et al. Developing a reliable mouse model for cancer therapy-induced cardiovascular toxicity in cancer patients and survivors. Front. Cardiovasc. Med. 5 , 1–13 (2018).

Parihar, V. K. et al. Cosmic radiation exposure and persistent cognitive dysfunction. Sci. Rep. 6 , 34774 (2016).

Parihar, V. K. et al. Persistent nature of alterations in cognition and neuronal circuit excitability after exposure to simulated cosmic radiation in mice. Exp. Neurol. 305 , 44–55 (2018).

Hinkle, J. J., Olschowka, J. A., Love, T. M., Williams, J. P. & O’Banion, M. K. Cranial irradiation mediated spine loss is sex-specific and complement receptor-3 dependent in male mice. Sci. Rep. 9 , 18899 (2019).

Liu, B. et al. Space-like 56Fe irradiation manifests mild, early sex-specific behavioral and neuropathological changes in wildtype and Alzheimer’s-like transgenic mice. Sci. Rep. 9 , 12118 (2019).

Raber, J. et al. Combined Effects of Three High-Energy Charged Particle Beams Important for Space Flight on Brain, Behavioral and Cognitive Endpoints in B6D2F1 Female and Male Mice. Front. Physiol. 10 , 1–15 (2019).

Rosi, S. The final frontier: transient microglia reduction after cosmic radiation exposure mitigates cognitive impairments and modulates phagocytic activity. Brain Circ. 4 , 109–113 (2018).

Kiffer, F., Boerma, M. & Allen, A. Behavioral effects of space radiation: a comprehensive review of animal studies. Life Sci. Space Res. (Amst.) 21 , 1–21 (2019).

Whoolery, C. W. et al. Multi-domain cognitive assessment of male mice shows space radiation is not harmful to high-level cognition and actually improves pattern separation. Sci. Rep. 10 , 2737 (2020).

Mader, T. H. et al. Optic disc edema, globe flattening, choroidal folds, and hyperopic shifts observed in astronauts after long-duration space flight. Ophthalmology 118 , 2058–2069 (2011).

Macias, B. et al. Anterior and posterior ocular structures change during long-duration spaceflight and one year after landing. Invest. Ophthalmol. Vis. Sci. 59 , 722 (2018).

Lee, A. G. et al. Spaceflight associated neuro-ocular syndrome (SANS) and the neuro-ophthalmologic effects of microgravity: a review and an update. NPJ Microgravity 6 , 1–10 (2020).

Brunstetter, T. J. & Tarver, W. J. Spaceflight Associated Neuro-ocular Syndrome (SANS): Current Clinical Insight & Questions of Interest (Translational Research Institute for Space Health - The Red Risk School, 2018).

Lee, J. K. et al. Head down tilt bed rest plus elevated CO 2 as a spaceflight analog: effects on cognitive and sensorimotor performance. Front. Hum. Neurosci. 13 , 1–11 (2019).

Lee, A. G., Mader, T. H., Gibson, C. R. & Tarver, W. Space flight-associated neuro-ocular syndrome. JAMA Ophthalmol. 135 , 992–994 (2017).

Zwart, S. R. et al. Vision changes after spaceflight are related to alterations in folate- and vitamin B-12-dependent one-carbon metabolism. J. Nutr. 142 , 427–431 (2012).

Zwart, S. R. et al. Association of genetics and B vitamin status with the magnitude of optic disc edema during 30-day strict head-down tilt bed rest. JAMA Ophthalmol. 137 , 1195–1200 (2019).

Patel, N., Pass, A., Mason, S., Gibson, C. R. & Otto, C. Optical coherence tomography analysis of the optic nerve head and surrounding structures in long-duration international space station astronauts. JAMA Ophthalmol. 136 , 193–200 (2018).

Roberts, D. R. et al. Effects of spaceflight on astronaut brain structure as indicated on MRI. N. Engl. J. Med. 377 , 1746–1753 (2017).

Van Ombergen, A. et al. Brain ventricular volume changes induced by long-duration spaceflight. Proc. Natl Acad. Sci. USA 116 , 10531–10536 (2019).

Alperin, N., Bagci, A. M. & Lee, S. H. Spaceflight-induced changes in white matter hyperintensity burden in astronauts. Neurology 89 , 2187–2191 (2017).

Kramer, L. A. et al. Intracranial effects of microgravity: a prospective longitudinal MRI Study. Radiology 295 , 640–648 (2020).

Dinges, D. F. et al. PVT on ISS: reaction self-test (RST) from 6-month missions. (Human Research Program Investigators’ Workshop, 2017).

Stuster, J. Behavioral Issues Associated with Isolation and Confinement: Review and Analysis of Astronaut Journals (NASA Human Research Program NASA/TM-2010-216130, 2016).

Basner, M. et al. Psychological and behavioral changes during confinement in a 520-day simulated interplanetary mission to mars. PLoS ONE 9 , e93298 (2014).

Barger, L. K. et al. Prevalence of sleep deficiency and use of hypnotic drugs in astronauts before, during, and after spaceflight: an observational study. Lancet Neurol. 13 , 904–912 (2014).

Greene, M. et al. ISS Habitability Data Collection and Preliminary Findings (Houston Human Factors and Ergonomic Society , 2018).

Lee, J. K. et al. Spaceflight-associated brain white matter microstructural changes and intracranial fluid redistribution. JAMA Neurol. 76 , 412–419 (2019).

Larson, L. et al. Team performance in space crews: Houston, we have a teamwork problem. Acta Astronaut. 161 , 108–114 (2019).

NASA Johnson Space Center. Nutritional Status Assessment for Extended-duration Space Flight . (NASA JSC Document #JSC-28566, Revision 1, 1999).

Smith, S. M. et al. Nutritional status assessment in semiclosed environments: ground-based and space flight studies in humans. J. Nutr. 131 , 2053–2061 (2001).

Smith, S. M., Zwart, S. R., Block, G., Rice, B. L. & Davis-Street, J. E. The nutritional status of astronauts is altered after long-term space flight aboard the International Space Station. J. Nutr. 135 , 437–443 (2005).

Smith, S. M., Zwart, S. R., Kloeris, V. & Heer, M. Nutritional Biochemistry of Space Flight . (Nova Science Publishers, 2009).

Smith, S. M., Gardner, K. K., Locke, J. & Zwart, S. R. Vitamin D supplementation during Antarctic winter. Am. J. Clin. Nutr. 89 , 1092–1098 (2009).

Zwart, S. R. et al. Response to vitamin D supplementation during Antarctic winter is related to BMI, and supplementation can mitigate Epstein-Barr Virus Reactivation. J. Nutr. 141 , 692–697 (2011).

Zwart, S. R. et al. Body mass changes during long-duration spaceflight. Aviat. Space Environ. Med. 85 , 897–904 (2014).

Smith, S. M., Zwart, S. R. & Heer, M. Human Adaptation to Spaceflight: the Role of Nutrition . (NASA Johnson Space Center #NP-2014-10-018-JSC, 2014).

Leach, C. S. et al. Regulation of body fluid compartments during short-term spaceflight. J. Appl. Physiol. 81 , 105–116 (1996).

Smith, S. M. et al. Benefits for bone from resistance exercise and nutrition in long-duration spaceflight: evidence from biochemistry and densitometry. J. Bone Miner. Res. 27 , 1896–1906 (2012).

Smith, S. M. et al. Fifty years of human space travel: implications for bone and calcium research. Annu. Rev. Nutr. 34 , 377–400 (2014).

Sibonga, J. D. et al. Adaptation of the skeletal system during long-duration spaceflight. Clin. Rev. Bone Miner. Metab. 5 , 249–261 (2008).

Smith, S. M., Heer, M. & Zwart, S. R. in Nutrition and bone health, 2nd edn . (eds. Holick, M. & Nieves, J.) 687–705 (Springer, 2015).

Sibonga, J. D., Spector, E. R., Johnston, S. L. & Tarver, W. J. Evaluating bone loss in ISS astronauts. Aerosp. Med. Hum. Perform. 86 (suppl. 1), 38–44 (2015).

LeBlanc, A. D., Spector, E. R., Evans, H. J. & Sibonga, J. D. Skeletal responses to space flight and the bed rest analog: a review. J. Musculoskelet. Neuronal Interact. 7 , 33–47 (2007).

CAS   PubMed   Google Scholar  

Schneider, V. S. et al. The Prevention of Bone Mineral Changes Induced by Bed Rest: Modification by Static Compression Simulating Weight Bearing, Combined Supplementation of Oral Calcium and Phosphate, Calcitonin Injections, Oscillating Compression, the Oral Diphosphonate Disodium Etidronate, and Lower Body Negative Pressure (Final Report) . (NASA CR-141453, 1974).

Maheshwari, U. R. et al. Comparison of fluoride balances during ambulation and bed rest. Proc. West. Pharmacol. Soc. 24 , 151–153 (1981).

Baecker, N., Frings-Meuthen, P., Smith, S. M. & Heer, M. Short-term high dietary calcium intake during bedrest has no effect on markers of bone turnover in healthy men. Nutrition 26 , 522–527 (2010).

Smith, S. M. et al. Men and women in space: bone loss and kidney stone risk after long-duration spaceflight. J. Bone Miner. Res. 29 , 1639–1645 (2014).

Zwart, S. R., Pierson, D., Mehta, S., Gonda, S. & Smith, S. M. Capacity of omega-3 fatty acids or eicosapentaenoic acid to counteract weightlessness-induced bone loss by inhibiting NF-kappaB activation: from cells to bed rest to astronauts. J. Bone Miner. Res. 25 , 1049–1057 (2010).

Heer, M. et al. Effects of high-protein intake on bone turnover in long-term bed rest in women. Appl. Physiol. Nutr. Metab. 42 , 537–546 (2017).

Zwart, S. R. et al. Amino acid supplementation alters bone metabolism during simulated weightlessness. J. Appl. Physiol. 99 , 134–140 (2005).

Zwart, S. R., Morgan, J. L. & Smith, S. M. Iron status and its relations with oxidative damage and bone loss during long-duration space flight on the International Space Station. Am . J. Clin. Nutr. 98 , 217–223 (2013).

Frings-Meuthen, P. et al. High sodium chloride intake exacerbates immobilization-induced bone resorption and protein losses. J. Appl. Physiol. 111 , 537–542 (2011).

Frings-Meuthen, P., Baecker, N. & Heer, M. Low-grade metabolic acidosis may be the cause of sodium chloride-induced exaggerated bone resorption. J. Bone Miner. Res. 23 , 517–524 (2008).

Heer, M. et al. Increasing sodium intake from a previous low or high intake affects water, electrolyte and acid-base differently. Br. J. Nutr. 101 , 1286–1294 (2009).

Zwart, S. R. et al. Dietary acid load and bone turnover during long-duration spaceflight and bed rest. Am. J. Clin. Nutr. 107 , 834–844 (2018).

Zwart, S. R. et al. Genotype, B-vitamin status, and androgens affect spaceflight-induced ophthalmic changes. FASEB J. 30 , 141–148 (2016).

Zwart, S. R. et al. Astronaut ophthalmic syndrome. FASEB J. 31 , 3746–3756 (2017).

Smith, S. M. & Zwart, S. R. Spaceflight-related ocular changes: the potential role of genetics, and the potential of B vitamins as a countermeasure. Curr. Opin. Clin. Nutr. Metab. Care 21 , 481–488 (2018).

Cucinotta, F. A. & Durante, M. Cancer risk from exposure to galactic cosmic rays: implications for space exploration by human beings. Lancet Oncol. 7 , 431–435 (2006).

Download references

Acknowledgements

This review was supported in part by a grant to Dr. Patel from the Translational Research Institute for Space Health (TRISH) from the Baylor College of Medicine (The Red Risk School). It was also supported by funding through NASA Human Health and Performance Contract #NNJ15HK11B (Z.S.P., S.R.Z., J.L.H.) and NASA directly (T.J.B., W.J.T., A.M.W., S.M.S., J.L.H.).

Author information

Authors and affiliations.

KBR, Houston, TX, USA

Zarana S. Patel

NASA Lyndon B. Johnson Space Center, Houston, TX, USA

Zarana S. Patel, William J. Tarver, Alexandra M. Whitmire, Sara R. Zwart & Scott M. Smith

U.S. Navy, NASA Lyndon B. Johnson Space Center, Houston, TX, USA

Tyson J. Brunstetter

University of Texas Medical Branch at Galveston, Galveston, TX, USA

Sara R. Zwart

NASA Langley Research Center, Hampton, VA, USA

Janice L. Huff

You can also search for this author in PubMed   Google Scholar

Contributions

Drs. Z.S.P. and J.L.H. compiled and edited the overall manuscript and drafted the radiation risk overviews. Drs. T.J.B. and W.J.T. drafted the SANS risk overview, Dr. A.M.W. drafted the behavioral health risks overview, and Drs. S.R.Z. and S.M.S. drafted the nutrition risk overview. Data are available upon request.

Corresponding author

Correspondence to Zarana S. Patel .

Ethics declarations

Competing interests.

All of the authors declare that they have no “competing interests” related to funding, person, or financial interest. Although the authors work directly (T.J.B., W.J.T., A.M.W., S.M.S., J.L.H.) as employees or indirectly as contractors (Z.S.P., S.R.Z.) for NASA, the views and opinions expressed here are those of the authors and do not necessarily reflect the views of NASA or the United States government.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ .

Reprints and permissions

About this article

Cite this article.

Patel, Z.S., Brunstetter, T.J., Tarver, W.J. et al. Red risks for a journey to the red planet: The highest priority human health risks for a mission to Mars. npj Microgravity 6 , 33 (2020). https://doi.org/10.1038/s41526-020-00124-6

Download citation

Received : 09 July 2020

Accepted : 30 September 2020

Published : 05 November 2020

DOI : https://doi.org/10.1038/s41526-020-00124-6

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

Quick links

• Explore articles by subject
• Guide to authors
• Editorial policies

Sign up for the Nature Briefing: Cancer newsletter — what matters in cancer research, free to your inbox weekly.

• Angles 2019: Table of Contents
• MIT Comparative Media Studies/Writing
• Umaer Basha Fund

Angles / 2019

selected essays from introductory writing subjects at MIT

Home » Headspace: How Space Travel Affects Astronaut Mental Health

Headspace: How Space Travel Affects Astronaut Mental Health

Image collage created by David Dezell Turner.

The year was 1982. Cosmonaut Valentin Lebedev, about five months into his 211-day mission on the Salyut 7 space station, began to notice that as his time spent aboard the station grew longer, the state of his mental health grew worse. In his journal, he described counting the days until the mission was over, becoming increasingly irritable with his fellow crew members and mission control — even when they were just asking, “How do you feel?” — and even losing his desire to look out the window. Lebedev’s fight with depression called attention to the need for more research into how the experience of space travel affects astronauts psychologically (Potter, 2008). Although there have been considerable advancements in space exploration since Lebedev’s mission, our understanding of space psychology still has a long way to go. Dr. Tyler Moore, a psychiatrist who has worked with NASA, explained in an e-mail to the author [1], “The main things that need investigation are all behavioral aspects. We’re pretty well prepped when it comes to the engineering…but the biggest unknown with potential to cause mission failure is the human factor” (Moore, 2018). An astronaut struggling with a behavioral health issue could make a mistake that jeopardizes the success of the mission or even the lives of crewmates (Caddy, 2018).

A poor sleep cycle can be counterproductive for astronauts, whose tasks can include anything from conducting experiments to repairing satellites, and it can also be potentially damaging to an astronaut’s mental health.

One major way in which space travel affects astronauts’ mental health is by disrupting their sleep schedules, a phenomenon MIT research scientist Dr. Andrew Liu has studied extensively. According to Liu, “Once you go up into space, there won’t be the same 24-hour clock necessarily that you get here on Earth…. So without that you have to either [set a sleep schedule] artificially or figure out some way to kind of maintain and ensure that people get enough sleep” (Liu, 2018). Because of their orbit around the Earth, for each 24-hour Earth day, astronauts on the International Space Station (ISS) see 16 sunrises and sunsets (NASA, 2018b). However, a drastic change in dark-light cycles isn’t the only cause of the disruption of astronaut sleep patterns; the other major culprit is the station’s artificial light. According to Liu, the artificial light on the station is largely made up of a specific wavelength of blue light. Unfortunately for the astronauts, “when you’re exposed to the blue light late at night, your body starts thinking, ‘Oh, you want to stay up later,’ so it tends to try and keep you up, so you don’t get the release of melatonin that helps you go to sleep….” (Television screens and computers also emit blue light, which is why watching these screens late at night can disrupt your sleep.) Liu also explains that people who consistently lose sleep tend to have decreased executive function, or the set of mental processes involving concentration and decision-making. When people consistently sleep fewer hours than needed, their performance on mental tests tends to decline, even though after a while they usually feel they have adjusted to the lack of sleep (Liu, 2018). A poor sleep cycle can be counterproductive for astronauts, whose tasks can include anything from conducting experiments to repairing satellites, and it can also be potentially damaging to an astronaut’s mental health. For example, when Valentin Lebedev was showing signs of depression, he also had a disorderly sleep schedule (Potter 2008). An astronaut suffering from a poor sleep cycle could also be potentially dangerous to the rest of the crew; for instance, an astronaut piloting a craft while sleep-deprived could end up putting his crewmates in peril.

However, when asked what aspect of space travel is potentially the most harmful to an astronaut’s mental health, Dr. Moore argues that it’s probably exposure to radiation. Earth’s atmosphere keeps us safe from most harmful radiation hurtling in from space. However, in space, astronauts have a higher chance of exposure to this radiation, which can cause radiation sickness or nervous system damage, and can even increase their chances of getting cancer (NASA, 2018a). Moore alludes to reports of astronauts “seeing ‘flashes’ while going to sleep,” which he says is likely due to particles “tearing through” their eyes and brains (Moore, 2018). Liu also explains that the effects of increased radiation exposure is one of the least understood dangers of longer missions: “The one wild card factor is probably radiation. Like, if there weren’t any radiation damage, you could probably get a good sense of how people would react to being on that mission and controlling their [blue] light exposure [for sleep].” (Liu, 2018). Since missions to Mars and beyond will be significantly longer than current space missions, the effects of radiation on astronauts require more research to be adequately understood.

Astronaut John Grunsfield’s work on the Hubble Space telescope is just one example of the many stressful tasks astronauts are expected to perform. (NASA, 2009)

In addition, outer space isn’t just a physically demanding environment, but a mentally and emotionally demanding one as well. Crew members are forced to live in a confined space, away from their families for long periods of time, and perform difficult tasks like satellite repairs with their work constantly examined by experts on earth. Sometimes the pressure gets to them; in the 1980s, Chinese payload specialist Taylor Wang threatened to not come back to earth after his experiment failed (NASA, 2016b; Morris, 2017). Other times, fear of the dangers of space can compromise a crew member; astronaut Harry Hartsfield said of a crewmate, “We had one payload specialist that became obsessed with the hatch. ‘You mean all I got to do is turn that handle and the hatch opens and all the air goes out?’ It was kind of scary…so we began to lock the hatch” (Morris, 2017). There was even report of an instance in which the entire crew of a mission might have shared the same delusion; in 1976, the Soviet Soyuz 21 mission had to be terminated after the crew complained of an awful smell. However, the cause of the smell was never found, and a recent NASA report proposed that the crew had simply imagined the smell (NASA, 2016b).

As nearly inhospitable as space is from a physiological health perspective, space itself may not be intrinsically dangerous to mental health (except for possibly radiation exposure). NASA psychiatrist Dr. Gary Beven asserts, “One misconception is a concern or theory that the spaceflight environment may be inherently harmful or hazardous, from a psychological standpoint…. Any previously reported behavioral health problems have appeared to occur because of common earthbound issues” (Inglis-Arkell, 2012). In fact, under two percent of medical issues reported on the 89 shuttle missions between 1981 and 1998 were due to behavioral health, while more than 40 percent were issues with adjusting to the lack of gravity (Morris, 2017). Beven also points out that these “earthbound issues” — such as having crew members with clashing personality types in a confined space — could have been the reason behind many of the psychological issues of the Mir and Salyut missions (Inglis-Arkell, 2012). For instance, tensions were reportedly running high between the cosmonauts of the Soyuz 21 mission to the Salyut 5 station – the same mission that was terminated after the crew reported a terrible smell (NASA, 2016b). Also, according to Beven, some NASA astronauts aboard the Mir space station struggled with depression and feelings of loneliness (Inglis-Arkell, 2012).

Surprisingly, some studies suggest space travel can actually be good for an astronaut’s mental well-being.

Surprisingly, some studies suggest space travel can actually be good for an astronaut’s mental well-being. In a 2007 study, psychiatric researchers Dr. Jennifer Ritsher, Dr. Nick Kanas, Dr. Eva Ilhe, and Stephanie Saylor conclude, based on a group of previously conducted surveys, that space missions provide an example of salutogenesis , a process in which people are positively impacted by having to adapt to a harsh and stressful environment. This same phenomenon happens to some individuals in similarly nigh-uninhabitable environments, such as researchers at polar stations or people who travel in submarines. Researchers measured the subjects’ stress levels before and after they adapted to their respective harsh environments, and the experience of adaptation actually seemed to reduce their stress levels. Surveys suggest that many astronauts undergo the same kind of adaptation (Ritsher, Kanas, Ihle, & Saylor, 2007). In one study, Ritsher, Ihle, and Kanas sent anonymous surveys to 175 astronauts; of the 39 who returned the survey, all reacted positively to the experience of spaceflight, leading the researchers to conclude that “being in space is a meaningful experience that makes an enduring positive impression on astronauts and cosmonauts” (Ihle, Ritsher, & Kanas, 2006).  The authors caution, however, that these conclusions “must be considered tentative given the small sample size and the potential for self-selection bias” (Ihle, Ritsher and Kanas, 2006).

Another survey of 54 astronauts reported that the “shared experience and excitement of space flight” helped improve their communication with both mission control and their fellow crewmates (Ritsher, Kanas, Ihle, & Saylor, 2007). Another team of researchers analyzed the memoirs of U.S. astronauts John Glenn, Gordon Cooper, “Buzz” Aldrin, and Michael Collins; the team noticed that all four astronauts reported that their experiences in space increased their spirituality (Suedfeld & Weiszbeck, 2004; Ritsher, Kanas, Ihle, & Saylor, 2007).

Surprisingly, one factor that likely contributes to this salutogenic effect is astronauts’ recognition and acceptance of the potential for danger. Retired astronaut Marsha Ivins explains, “We understand the danger involved in human spaceflight, and we accept the risk because we feel the reward of human space exploration is worth taking that risk.” She goes on to explain that even though training and spaceflight forces astronauts to spend years under intense pressure, “the experience overall is one of a mental high” (Ivins, 2019). Unfortunately, this emphasis on success under pressure can deter some astronauts from seeking psychiatric help when they need it; these astronauts may feel they can handle issues on their own and believe seeking psychiatric help indicates a weakness (Hylton, 2007). Still, according to NASA psychiatrist Gary Beven, astronauts aboard the ISS generally adapt to the environment after about six weeks, and many want to stay in space even longer. Beven maintains that “with six properly selected and well trained crew members in a relatively large living and working space, astronauts and cosmonauts truly thrive in such a spaceflight environment” (Inglis-Arkell, 2012).

Lebedev was struggling with depression after only seven months; a roundtrip mission to Mars would take about 18 months (Liu, 2018).

Despite some evidence of space travel promoting salutogenesis, however, the lack of data on the behavioral side of space psychology means that the positive and negative effects of space travel on behavioral health are still inadequately understood. Many of the studies exploring astronaut mental health have relatively small sample sizes, as research is limited by the number of people who have travelled to space (Ritsher, Kanas, Ihle, & Saylor, 2007). The lack of information available in the field of space psychology becomes an even more pressing issue when one considers the fact that we know even less about how astronauts will react to longer missions. Lebedev was struggling with depression after only seven months; a roundtrip mission to Mars would take about 18 months (Liu, 2018). Even Ritsher, Kanas, Ihle, and Saylor concede, “The level of stress is expected to be even higher on the planned expedition class missions to Mars. Therefore, the risk of negative mental health effects… is not negligible and poses a serious threat to mission success” (Ritsher, Kanas, Ihle, & Saylor, 2007). Understanding the nature and causes of these potential behavioral issues and creating measures to mitigate them is of the utmost importance if we want to send astronauts to Mars and beyond.

Fortunately, NASA is making efforts to decrease mental health risks for astronauts. A large portion of these efforts include designing realistic simulations of space missions here on Earth. In 2014, NASA debuted the Human Exploration Research Analog (HERA), a habitat at Johnson Space Center designed to simulate a variety of missions, including a journey to an asteroid. HERA replicates the isolation and confinement of space missions, as well as other aspects of life in space. Just as on a real mission, HERA “astronauts” adhere to strict sleep schedules and mainly consume freeze-dried foods. The crew is also kept in constant contact with mission control, but just as on an actual mission of this magnitude, communications suffer from a 10-minute delay (NASA, 2019; Mallonee, 2017). Missions can last for up to 45 days (NASA, 2019). Though HERA is not a perfect simulation — as HERA cannot, for instance, replicate microgravity — the habitat does have virtual reality helmets onboard, allowing the astronauts to simulate tasks such as piloting the craft and walking in space. The nine video cameras onboard and the biometric trackers worn by the participants allow NASA to constantly monitor the crew (Mallonee, 2017). HERA is just one of many analog missions helping NASA to better understand how the confinement and isolation of space travel affects astronauts psychologically (NASA, 2016a).

Potential astronauts are given training to strengthen skills that are imperative to mission success, such as conflict resolution, leadership, and stress management (Clay, 2016).

Furthermore, potential NASA astronauts are required to undergo extensive psychological evaluations and training to even be considered for the astronaut program (Lewis 2014; Clay 2016). The evaluation process begins with a preliminary set of interviews, followed by a set of psychiatric interviews. A psychiatrist examines applicants for factors that could potentially disqualify them, such as mental illness or even marital problems (Lewis, 2014). Applicants deemed to have the highest chances of having a behavioral emergency in space are disqualified. Astronaut candidates are also scored based on “personality, emotional stability, interviews, assessed performance in the field exercises, and family demands” to determine their suitability for space travel (NASA, 2016). In addition to these assessments, candidates must perform a series of field exercises at Johnson Space Center designed to replicate the conditions of a real mission (Lewis, 2014). Potential astronauts are given training to strengthen skills that are imperative to mission success, such as conflict resolution, leadership, and stress management (Clay, 2016). Since people can change over time, the psychiatric evaluation and training process is imperfect and can become less accurate as more time passes (NASA, 2016b). Nevertheless, thorough psychological evaluations are a necessity for the success of future missions and for minimizing mental health risks in space.

Mission crews also have medical countermeasures in case a behavioral emergency arises. On the space shuttle, medical kits contained medications for depression, psychosis, anxiety, insomnia, fatigue, pain, and space motion sickness. The current medical kit on the ISS includes two antidepressants, two antipsychotics, and two anxiolytics (to treat anxiety). (Unfortunately, there isn’t much data on how these drugs would affect a human body in microgravity.) Additionally, crew medical officers and flight surgeons have access to sedatives and physical restraints in the event that a crew member’s behavioral emergency threatens the safety of the rest of the crew (NASA, 2016b).

The International Space Station crew celebrating New Year’s together. (NASA, 2017)

Another way to decrease mental health risks is to increase the crew’s chances of undergoing a salutogenic experience (Ritsher, Kanas, Ihle, & Saylor,  2007), which is exactly why NASA has a Behavioral Health Team. The Behavioral Health Team tries to do everything it can to keep these spacebound astronauts feeling grounded, including remotely checking crew members’ behavioral health, consulting to help create safe work-rest schedules to prevent overworking, and working with clinical psychiatrists to provide aid should any mental health issues arise. They also encourage crew members’ families to make care packages (or they make some themselves), and they send them up to the International Space Station. A team of psychological support coordinators also helps astronauts video conference with their families. According to Beven, astronauts on the ISS are given “adequate sleep, healthy and good tasting food, exercise, meaningful work, leisure time, the availability of social and recreational events – music, movies, contact with family and friends – privacy, adequate space, and a supportive ground team” (Inglis-Arkell, 2012). Scientists are even looking into different kinds of lighting that will hopefully be less harmful to astronaut sleep patterns (Brainard, 2018). While the uncertainty concerning the psychological impacts of longer missions still remains, developments like these provide hope for maintaining the mental health of astronauts in future space travel.

Imagine the year 2032. A crew of NASA astronauts are about five months into their 18-month mission to Mars. The journey isn’t perfect, but everyone on this crew knows that they have extensive resources for emotional support if anything goes wrong. Space is enormously stressful, but they’re all braving it together. They’ll adapt. They’ll roll with the punches. And thanks to the hard work of space psychologists, all of them will be the better for it.

Brainard, G. C., & Lockley, S. W. (2018, November 8). Testing Solid State Lighting Countermeasures to Improve Circadian Adaptation, Sleep, and Performance During High Fidelity Analog and Flight Studies for the International Space Station. Retrieved July 22, 2019, from https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=2013

Caddy, B. (2018, July 09). The tech that could keep astronauts happy on their missions to the stars. TechRadar. Retrieved July 22, 2019, from https://www.techradar.com/news/the-tech-that-could-keep-astronauts-happy-on-their-missions-to-the-stars

Clay, R. (2016, September). 4 questions for Kelly Slack, PhD. Monitor on Pyschology, 47 (8). Retrieved July 21, 2019, from https://www.apa.org/monitor/2016/09/people-slack

Hylton, H. (2007, February 8). Why Astronauts Don’t Like Shrinks. Time. Retrieved July 22, 2019, from http://content.time.com/time/health/article/0,8599,1587495,00.html

Ihle, E. C., Ritsher, J. B., & Kanas, N. (2006). Positive psychological outcomes of spaceflight: an empirical study. Aviation, Space, and Environmental Medicine , 77 (2), 93–101.

Ivins, M. (2017, March 29). What Hollywood Gets Wrong About Female Astronauts and the Reality of Space. Time. Retrieved July 21, 2019, from https://time.com/4716473/hollywood-misconceptions-about-female-astronauts-space/

Inglis-Arkell, E. (2012, December 11). What Does Space Travel Do to Your Mind? NASA’s Resident Psychiatrist Reveals All. Gizmodo. Retrieved July 22, 2019, from https://io9.gizmodo.com/5967408/what-does-space-travel-do-to-your-mind-nasas-resident-psychiatrist-reveals-all

Lewis, R. (2015, February 23). Behavioral Health. Retrieved July 22, 2019, from http://www.nasa.gov/content/behavioral-health

Lewis, T. (2014, August 12). The Right (Mental) Stuff: NASA Astronaut Psychology Revealed. Space.com . Retrieved July 21, 2019, from https://www.space.com/26799-nasa-astronauts-psychological-evaluation.html

Liu, A. (2018, December 4). Personal interview.

Mallonee, L. (2017, November 07). Spending 45 Days Inside a Fake Spaceship in the Name of Science. Wired. Retrieved July 21, 2019, from https://www.wired.com/story/nasa-hera-space-simulator-mission/

Moore, T. (2018, December 1). E-mail.

Morris, N. P. (2017, March 14). Mental Health in Outer Space. Retrieved December 1, 2018, from https://blogs.scientificamerican.com/guest-blog/mental-health-in-outer-space/

National Aeronautics and Space Administration. (2016a, February 17). About Analog Missions. Retrieved July 21, 2019, from https://www.nasa.gov/analogs/what-are-analog-missions

National Aeronautics and Space Administration. (2016b, April 11). Evidence Report: Risk of Adverse Cognitive or Behavioral Conditions and Psychiatric Disorders (Behavioral and psychiatric emergencies). Retrieved July 22, 2019, from https://humanresearchroadmap.nasa.gov/Evidence/reports/BMed.pdf

National Aeronautics and Space Administration. (2018a, April 13). Why Space Radiation Matters. Retrieved July 22, 2019, from https://www.nasa.gov/analogs/nsrl/why-space-radiation-matters

National Aeronautics and Space Administration. (2018b, April 27). International Space Station Facts and Figures. Retrieved July 22, 2019, from https://www.nasa.gov/feature/facts-and-figures

NASA. (2019, July). Human Research Program Human Exploration Research Analog (HERA) Facility and Capabilities Information. Retrieved July 21, 2019, from https://www.nasa.gov/sites/default/files/atoms/files/2019_hera_facility_capabilities_information.pdf

Potter, N. (2008, August 18). Feeling Low Up High: the Lonely Astronaut. Retrieved December 2, 2018, from https://abcnews.go.com/Technology/story?id=5588291&page=1

Ritsher, J. B., Kanas, N. A., Ihle, E. C., & Saylor, S. A. (2007). Psychological adaptation and salutogenesis in space: Lessons from a series of studies. Acta Astronautica , 60 (4), 336–340. https://doi.org/10.1016/j.actaastro.2006.09.002

Serrano, A. (2007, February 06). Astronaut Nabbed In Bizarre Kidnap Plot. CBS News. Retrieved July 22, 2019, from https://www.cbsnews.com/news/astronaut-nabbed-in-bizarre-kidnap-plot/

Suedfeld, P., & Weiszbeck, T. (2004). The impact of outer space on inner space [Abstract].  Aviat Space Environ Med,75 (7). Retrieved July 22, 2019, from https://www.ncbi.nlm.nih.gov/pubmed/15267069 .

Image Citations

National Aeronautics and Space Administration. (2009). A Week of Work on the Hubble Telescope [Photograph]. Retrieved from https://www.nasa.gov/multimedia/imagegallery/image_Feature_1355.html

National Aeronautics and Space Administration. (2017). Astronauts celebrating New Year’s [Photograph]. Retrieved from https://www.space.com/35195-space-station-rings-in-2017.html

[1]The research for this article involved both primary and secondary sources. The author conducted an e-mail interview with psychiatrist Dr. Tyler Moore and a face-to-face interview with MIT research scientist Dr. Andrew Liu.

Back to the Table of Contents

David Dezell Turner

About the author

David Dezell Turner is a member of the class of 2022 majoring in aerospace engineering. He was born and raised in Iowa, like Peggy Whitson and Captain Kirk, which means he basically has space exploration (and corn) coursing through his veins. When he’s not studying, he’s serving as an ambassador for NASA’s Lucy Mission, singing in the MIT Gospel Choir, or drawing with an Etch-A-Sketch. Turner stumbled across the issue of astronaut mental health while researching spacesuits, and much to his surprise, what began as an assignment quickly became an issue he cared deeply about.

Subject: 21W.035 Berezin

Assignment: Investigative Article

• Entries RSS
• Comments RSS
• WordPress.org
• MIT Comparative Media Studies / Writing

Proudly powered by WordPress / Theme: Academica by WPZOOM .

• Full IELTS Practice Tests
• Practice Tests

Space Travel and Health

• View Solution

Solution for: Space Travel and Health

Answer table.

 Found a mistake? Let us know!

 Share this Practice Test

Exam Review

A. Space biomedicine is a relatively new area of research both in the USA and in Europe. Its main objectives are to study the effects of space travel on the human body, identifying the most critical medical problems, and finding solutions to those problems. Space biomedicine centers are receiving increasing direct support from NASA and/or the European Space Agency (ESA).

B. This involvement of NASA and the ESA reflects growing concern that the feasibility of travel to other planets, and beyond, is no longer limited by engineering constraints but by what the human body can actually withstand. The discovery of ice on Mars, for instance, means that there is now no necessity to design and develop a spacecraft large and powerful enough to transport the vast amounts of water needed to sustain the crew throughout journeys that may last many years. Without the necessary protection and medical treatment, however, their bodies would be devastated by the unremittingly hostile environment of space.

C. The most obvious physical changes undergone by people in zero gravity are essentially harmless; in some cases, they are even amusing. The blood and other fluids are no longer dragged down towards the feet by the gravity of Earth, so they accumulate higher up in the body, creating what is sometimes called ‘fat face`, together with the contrasting ‘chicken legs’ syndrome as the lower limbs become thinner.

D. Much more serious are the unseen consequences after months or years in space. With no gravity, there is less need for a sturdy skeleton to support the body, with the result that the bones weaken, releasing calcium into the bloodstream. This extra calcium can overload the kidneys, leading ultimately to renal failure. Muscles too lose strength through lack of use. The heart becomes smaller, losing the power to pump oxygenated blood to all parts of the body, while the lungs lose the capacity to breathe fully. The digestive system becomes less efficient, a weakened immune system is increasingly unable to prevent diseases and the high levels of solar and cosmic radiation can cause various forms of cancer.

E. To make matters worse, a wide range of medical difficulties can arise in the case of an accident or serious illness when the patient is millions of kilometers from Earth. There is simply not enough room available inside a space vehicle to include all the equipment from a hospital’s casualty unit, some of which would not work properly in space anyway. Even basic things such as a drip depend on gravity to function, while standard resuscitation techniques become ineffective if sufficient weight cannot be applied. The only solution seems to be to create extremely small medical tools and ‘smart` devices that can, for example, diagnose and treat internal injuries using ultrasound. The cost of designing and producing this kind of equipment is bound to be, well, astronomical.

F. Such considerations have led some to question the ethics of investing huge sums of money to help a handful of people who, after all, are willingly risking their own health in outer space, when so much needs to be done a lot closer to home. It is now clear, however, that every problem of space travel has a parallel problem on Earth that will benefit from the knowledge gained and the skills developed from space biomedical research. For instance, the very difficulty of treating astronauts in space has led to rapid progress in the field of telemedicine, which in turn has brought about developments that enable surgeons to communicate with patients in inaccessible parts of the world. To take another example, systems invented to sterilize wastewater onboard spacecraft could be used by emergency teams to filter contaminated water at the scene of natural disasters such as floods and earthquakes. In the same way, miniature monitoring equipment, developed to save weight in space capsules, will eventually become tiny monitors that patients on Earth can wear without discomfort wherever they go.

G. Nevertheless, there is still one major obstacle to carrying out studies into the effects of space travel: how to do so without going to the enormous expense of actually working in space. To simulate conditions in zero gravity, one tried and tested method is to work underwater, but the space biomedicine centers are also looking at other ideas. In one experiment, researchers study the weakening of bones that results from prolonged inactivity. This would involve volunteers staying in bed for three months, but the center concerned is confident there should be no great difficulty in finding people willing to spend twelve weeks lying down.AII in the name of science, of course.

Questions 1-5

Reading Passage 1 has seven paragraphs A-G. Choose the correct heading for paragraphs B-E and G from the list of headings below. Write the correct member (i-x) in boxes 1—5 on your answer sheet.

List of Headings

i. The problem of dealing with emergencies in space ii. How space biomedicine can help patients on Earth iii. Why accidents are so common in outer space iv. What is space biomedicine? v. The psychological problems of astronauts vi. Conducting space biomedical research on Earth vii. The internal damage caused to the human body by space travel viii. How space biomedicine First began ix. The visible effects of space travel on the human body x. Why space biomedicine is now necessary

Example Paragraph A Answer iv 1 i ii iii iv v vi vii viii ix x Paragraph B Answer: x 2 i ii iii iv v vi vii viii ix x Paragraph C Answer: ix 3 i ii iii iv v vi vii viii ix x Paragraph D Answer: vii 4 i ii iii iv v vi vii viii ix x Paragraph E Answer: i Example Paragraph F Answer ii 5 i ii iii iv v vi vii viii ix x Paragraph G Answer: vi

Questions 6-7

Answer the questions below using NO MORE THAN THREE WORDS for each answer. 6. Where, apart from Earth, can space travelers find water?  6 Answer: (ON/FROM) MARS 7. What happens to human legs during space travel?  7 Answer: THEY BECOME THINNER

Questions 8-12

Do the following statements agree with the writer’s views in Reading Passage?  Write YES if the statement agrees with the views of the writer NO, if the state does not agree with the views of the writer NOT GIVEN if there is no information about this in the passage

8 YES NO NOT GIVEN The obstacles to going far into space are now medical, not technological. Answer: YES 9 YES NO NOT GIVEN Astronauts cannot survive more than two years in space. Answer: NOT GIVEN 10 YES NO NOT GIVEN It is morally wrong to spend so much money on space biomedicine. Answer: NO 11 YES NO NOT GIVEN Some kinds of surgery are more successful when performed in space. Answer: NOT GIVEN 12 YES NO NOT GIVEN Space biomedical research can only be done in space. Answer: NO

Questions 13-14

Complete the table below. Choose NO MORE THAN THREE WORDS from the passage for each answer

Other Tests

• 5 - YES-NO-NOT GIVEN
• 4 - Matching Information
• 5 - Sentence Completion

Personality and appearance

• Recent Actual Tests
• 0 unanswered

The Plan to Bring an Asteroid to Earth

• 6 - TRUE-FALSE-NOT GIVEN
• 7 - Summary, form completion

The history of tea

The history of dolls.

• 9 - TRUE-FALSE-NOT GIVEN
• 5 - Summary, form completion

The Bite That Heat

• 5 - TRUE-FALSE-NOT GIVEN
• 4 - Sentence Completion
• 4 - Summary, form completion

The dugong: sea cow

Found a mistake let us know.

Please descibe the mistake as details as possible along with your expected correction, leave your email so we can contact with you when needed.

Describe what is wrong with the practice test:

Please enter description

Enter your name:

Enter your email address:

Please enter a valid email

Space Travel And Health- IELTS Reading Answers

15 min read

Updated On Aug 14, 2024

Share on Whatsapp

Share on Email

Share on Linkedin

Table of Contents

Reading passage, space travel and health, answers of space travel and health reading answers with location and explanations, tips to solve the question types in space travel and health ielts reading answers.

Limited-Time Offer : Access a FREE 10-Day IELTS Study Plan!

Various question types are asked in IELTS Academic Reading to test specific reading skills and some of them are given in Space Travel and Health IELTS Reading Answers. These question types are:

• IELTS Reading Matching Headings to Paragraphs
• Short Answer Questions IELTS Reading
• IELTS Reading Yes, No, Not Given
• IELTS Reading Table Completion

Ideally, IELTS test-takers should take around 20 minutes to solve a passage like ‘Space Travel and Health’ in IELTS Academic Reading. Therefore, to master this skill, they need to take  IELTS reading practice tests  regularly. Let’s see how easy this passage is for you and if you’re able to make it in 20 minutes.

Questions of SPACE TRAVEL AND HEALTH

Questions 1-5

Reading Passage 1 has seven paragraphs A-G.

Choose the correct heading for paragraphs B-E and G from the list of headings below.

Write the correct member (i-x) in boxes 1—5 on your answer sheet.

List of Headings

i. The problem of dealing with emergencies in space

ii. How space biomedicine can help patients on Earth

iii. Why accidents are so common in outer space

iv. What is space biomedicine?

v. The psychological problems of astronauts

vi. Conducting space biomedical research on Earth

vii. The internal damage caused to the human body by space travel

viii. How space biomedicine First began

ix. The visible effects of space travel on the human body

x. Why space biomedicine is now necessary

Example Paragraph A Answer iv

• Paragraph B
• Paragraph C
• Paragraph D
• Paragraph E

Example Paragraph F Answer ii

• Paragraph G

Questions 6 and 7

6 Where, apart from Earth, can space travelers find water? ………….

7 What happens to human legs during space travel? ……………..

Questions 8-12

Do the following statements agree with the writer’s views in Reading Passage 1? Write

YES if the statement agrees with the views of the writer

NO, if the state does not agree with the views of the writer

NOT GIVEN if there is no information about this in the passage

8 The obstacles to going far into space are now medical, not technological.

9 Astronauts cannot survive more than two years in space.

10 It is morally wrong to spend so much money on space biomedicine.

11 Some kinds of surgery are more successful when performed in space.

12 Space biomedical research can only be done in space.

Questions 13-14

Research area

Application in space

Application on Earth

Telemedicine

treating astronauts

13 ……….. in remote areas

Sterilization

sterilizing wastewater

14 …………….in disaster zones

Miniaturization

saving weight

wearing small monitors comfortably

Go through the answers and detailed explanations of each question in the Space Travel and Health passage and prepare to get a high IELTS Reading band score . 

1 Answer:  x

Question type:  Matching Headings

Answer location:  Paragraph B

Answer explanation:  Paragraph B illustrates, “This involvement of  NASA and the ESA reflects growing concern that the feasibility of travel to other planets, and beyond, is no longer limited by engineering constraints but by what the human body can actually withstand. The discovery of ice on Mars,  for instance, means  that there is now no necessity to design and develop a spacecraft large and powerful enough to transport the vast amounts of water needed to sustain the crew throughout journeys that may last many years. Without the necessary protection and medical treatment, however, their bodies would be devastated by the unremittingly hostile environment of space.”  We can deduce from these lines that the feasibility of traveling to other planets is no longer confined by engineering constraints but by what the human body can actually withstand. However, in the last line of the paragraph, it is revealed that without necessary protection and medical treatment, the bodies will be destroyed by the hostile environment of space. As a result, space biomedicine is very important. Thus, the answer is x.

2 Answer:  ix

Answer location:  Paragraph C

Answer explanation:  The initial lines of paragraph C state that the  most obvious physical changes undergone by people in zero gravity are essentially harmless ; in some cases, they are even  amusing . The  blood and other fluids are no longer dragged down towards the feet by the gravity of Earth , so they  accumulate higher up in the body,  creating what is sometimes called  ‘fat face`, together with the contrasting ‘chicken legs’ syndrome as the lower limbs become thinner.  These lines suggest that the physical changes of a person in zero gravity are harmless and are sometimes amusing too. Thus, it is clear that paragraph C explains the visible effects of space travel on the human body. Therefore, the answer is ix.

3 Answer:  vii

Answer location:  Paragraph D

Answer explanation:  Paragraph D states that much more  serious are the unseen consequences after months or years in space.  With no gravity, there is less need for a  sturdy skeleton to support the body , with the result that the  bones weaken, releasing calcium into the bloodstream . This extra calcium can  overload the kidneys, leading ultimately to renal failure . Muscles too lose strength through lack of use. The heart becomes  smaller, losing the power to pump oxygenated blood to all parts of the body, while the lungs lose the capacity to breathe fully.  The  digestive system  becomes  less efficient , a weakened  immune system is increasingly unable to prevent diseases  and the high levels of  solar and cosmic radiation can cause various forms of cancer . We understand that paragraph D elucidates the possible effects and diseases that a human body living in space would have. As a result, the paragraph discusses the internal damage caused to the human body by space travel. Thus, the answer is vii.

4 Answer:  i

Answer location:  Paragraph E

Answer explanation:  In paragraph E, it is mentioned that to make matters worse, a wide range of  medical difficulties can arise in the case of an accident or serious illness when the patient is millions of kilometers from Earth.  There is simply not  enough room  available inside a  space vehicle to include all the equipment from a hospital’s casualty unit , some of which would not work  properly in space anyway . Even basic things such as  a drip depend on gravity to function, while standard resuscitation techniques become ineffective if sufficient weight cannot be applied.  The only solution seems to be to create extremely  small medical tools and ‘smart` devices that can , for example,  diagnose and treat internal injuries using ultrasound . The cost of  designing and producing this kind of equipment is bound to be, well, astronomical.  These lines indicate the problems of dealing with emergencies in space, for instance, even a drip depends on gravity to function while resuscitation techniques are ineffective if weight is not applied. Moreover, there’s no room for more medical equipment in the space. Thus, the answer is i.

5 Answer:  vi

Answer location:  Paragraph G

Answer explanation:  Paragraph G states the fact that  nevertheless, there is still one major obstacle to carrying out studies into the effects of space travel :  how to do so without going to the enormous expense of actually working in space . To  simulate conditions in zero gravity ,  one tried and tested method is to work underwater , but  the space biomedicine centers are also looking at other ideas . In one experiment, researchers study the  weakening of bones that results from prolonged inactivity . This would involve  volunteers staying in bed for three months , but the center is confident there should be no  great difficulty in finding people willing to spend twelve weeks lying down . AII in the name of science, of course. We understand from these lines that conducting space biomedical research on Earth is difficult as it’d be challenging to do the research without actually visiting the space. As a result, space biomedicine centers are looking for other alternative ideas. Thus, the answer is vi.

6 Answer:  (on/ from) Mars

Question type:  Short Answer Question

Answer location:  Paragraph B, line 2

Answer explanation:  The 2nd line of paragraph B states that the  discovery of ice on Mars,  for instance, means that there is now  no necessity to design and develop a spacecraft large and powerful enough to transport the vast amounts of water  needed to  sustain the crew throughout journeys that may last many years.  We can deduce from these lines that the discovery of ice on Mars reflected that there’s no necessity of developing or designing a spacecraft to transport water required to sustain the crew. Therefore, space travelers can find water on Mars apart from the Earth. Thus, the answer is (in/on) Mars.

7 Answer:  they become thinner

Answer location:  Paragraph C, last line

Answer explanation:  Paragraph C illustrates the  obvious effects of space travel on the human body.  The last line of the paragraph reveals that the  blood and other fluids are no longer dragged down  towards the feet by the gravity of Earth, so they  accumulate higher up in the body,  creating what is sometimes called  ‘fat face`,  together with the  contrasting ‘chicken legs’ syndrome  as the  lower limbs become thinner . Thus, it is evident that human legs become thinner during space travel. So, the answer is they become thinner.

8 Answer:  Yes

Question type:  Yes/ No/ Not Given

Answer location:  Paragraph A, line 2

Answer explanation:  The 2nd line of paragraph A states that its  main objectives are to study the effects of space travel on the human body, identify the most critical medical problems, and find solutions to those problems . These lines indicate that the primary aim of studying the effects of space travel on the human body is to identify important medical problems and find appropriate solutions to these problems. Thus, the statement agrees with the information, so, the answer is Yes.

9 Answer:  Not Given

Answer location:  Paragraph F

Answer explanation:  We find a reference for Astronauts in Paragraph F, where it is mentioned that the  very difficulty of treating astronauts in space has led to rapid progress in the field of telemedicine,  which in turn has brought about  developments that enable surgeons to communicate with patients in inaccessible parts of the  world. These lines suggest that the difficulty of treating Astronauts in space has resulted in the progress of telemedicine. However, there’s no reference to the fact that Astronauts survive for more than two years in space. Thus, the answer is Not Given.

10 Answer:  No

Answer explanation:  The introductory lines of paragraph F states that such  considerations have led some to question the ethics of investing huge sums of money  to help a  handful of people who, after all, are willingly risking their own health in outer space , when so many needs to be done a lot closer to home. These lines suggest that considerations have resulted in the ethics of investing huge amounts of money to help people who are willing to risk their own health in outer space. It is clear that people are willing to spend money on space biomedicine. Thus, the statement contradicts the information, so, the answer is No.

11 Answer:  Not Given

Answer location:  Paragraph E, line 2

Answer explanation:  We know paragraph E explains the problems of dealing with emergencies in space. The 2nd line of paragraph E state, that there is  simply not enough room available inside a space vehicle to include all the equipment from a hospital’s casualty unit , some of which  would not work properly in space anyway.  Even basic things such as a  drip depend on gravity to function, while standard resuscitation techniques become ineffective if sufficient weight cannot be applied . The only solution seems to be to create extremely  small medical tools and ‘smart` devices  that can, for example, diagnose and treat internal injuries using ultrasound. These lines suggest how to deal with problems in space. It is stated that there’s no room to include much medical equipment in space, some of which wouldn’t work. Therefore, it is not mentioned anywhere in the paragraph that surgery is successful when performed in space. Thus, the answer is Not Given.

12 Answer:  No

Answer explanation:  Paragraph G explains conducting space biomedical research on Earth. The initial lines suggest that nevertheless, there is still one  major obstacle to carrying out studies into the effects of space travel :  how to do so without going to the enormous expense of actually working in space.  To simulate conditions in zero gravity,  one tried and tested method is to work underwater , but the  space biomedicine centers are also looking at other ideas.  We can deduce from these lines that there’s another tried and tested method of conducting space biomedical research, which is to work underwater. However, space biomedicine centers are looking for other alternatives. Therefore, the statement contradicts the information, so, the answer is No.

13 Answer:  communicate with patients

Question type:  Table Completion

Answer explanation:  Paragraph F illustrates an example stating that  the very difficulty of treating astronauts in space has led to rapid progress in the field of telemedicine, which in turn has brought about developments that enable surgeons to communicate with patients in inaccessible parts of the world.  These lines indicate that the difficulty of treating astronauts in space has resulted in the progress of telemedicine. It has brought developments that allow surgeons to communicate with patients even in inaccessible areas. Thus, the answer is to Communicate with patients.

14 Answer:  filter contaminated water

Answer explanation:  Another example of sterilization can be found in paragraph F, which states that the systems invented to  sterilize wastewater onboard spacecraft  could be used by  emergency teams to filter contaminated water at the scene of natural disaster s such as floods and earthquakes. These lines indicate that systems were invented to sterilize wastewater, which could be used by the emergency teams to filter contaminated water in disaster zones. Thus, the answer is to filter contaminated water.

Now that you have the answers and explanations for Space Travel and Health Reading Answers, let’s explore some IELTS exam preparation tips for answering the four question types.

Matching Headings: 

You must match the heading in this type of question to the appropriate paragraph or reading segment in the text to score a high IELTS band score . Your ability to figure out the paragraph’s key concept and its supporting ideas will be put to the test.

• Take your time to rephrase the potential headings’ keywords.
• Find the main idea from the paragraphs by using IELTS Reading keyword techniques . Sometimes the essential idea of the paragraph is expressed in the header.
• For clarification on the paragraph’s main idea, see the first and last sentences. Likewise, quickly scan the middle of the paragraph to make sure you comprehend it.
• Don’t try to match words. Your primary goal is to match a correct paragraph.
• Choose the heading that best fits the paragraph after reading it again if two seem to be appropriate.
• The number of headings will always be greater than the number of paragraphs or sections. Therefore, some headings will never be utilized.

Short-Answer Type Questions: 

Short Answer Type Questions is a type of reading question in IELTS exam that requires you to scan through a passage and answer questions based on the information given following the word limit.  To answer them, you can use the following strategies:

• Go through the instructions carefully – You will find the word limit for the answers there, which you have to follow strictly .
• Read the questions and highlight the keywords – The next step will be to read the questions to know what keywords or information you have to look for in the passage.
• Use the ‘Wh’ words in the questions – Words like ‘What’, (names), ‘Where’ (place), ‘When’ (time), etc. will enable you to understand the type of information you are looking for.
• Use reading techniques to study the passage quickly – Do not waste your time reading the whole passage. Scan through the passage to find out the keywords or their synonyms. If headers are given, use them to locate the answer easily.
• Check the spelling – Once you find the answer, note the correct spelling in your answer sheet.

Yes/No/Not Given

Unlike True/False/Not Given IELTS Reading questions , ‘Yes/No/Not Given’ questions are based on opinions, views and beliefs of the author of the reading passage. A few statements will be provided to you, and it is up to you to determine whether they conform with the views/opinions of the writer by reading the text. Y ou can use the following strategies to answer this question type:

• Always begin by reading the question and identifying the keywords . Before reading the material, have a look at your list of Yes, No, and Not Given questions. 
• You need to scan the passage for synonyms or paraphrased words of the keywords . Once you have highlighted the keywords, swiftly read the text to look for paraphrases or synonyms.
• Matching highlighted words, or keywords in the questions with their synonyms in the text is the best way to figure out the answer . Once you find both sets of keywords, cross-check them to find the answer.
• Do NOT waste time if you are confused. If the facts match, the answer is YES, and in case it doesn’t match, it is NO. If you are unable to find the answer or unsure of it, mark it NOT GIVEN.

Table Completion:

The way to solve the table completion questions of the IELTS Reading is similar to IELTS Reading Summary Completion . You will be asked to fill in missing information in a table based on the information provided in the passage. Here’s a detailed guide on how to approach table completion effectively:

• Read the instructions carefully: Before you start reading the passage or table, make sure you understand what the question is asking for. Pay attention to the instructions provided for word limit.
• Skim the table and headings: Quickly glance over the table and its headings to get an idea of the structure and what information it contains. This will help you understand the context before you start reading in detail.
• Identify keywords: Look for keywords or key phrases in the question that will help you locate the relevant information in the passage or table. Circle or underline these keywords to stay focused while reading.
• Scan the passage: Scan the passage for the specific information mentioned in the question. You don’t need to read every word in detail; instead, look for keywords or related terms that match those in the question.
• Use context clues: Sometimes, the information needed to fill in the table may not be explicitly stated but can be inferred from the surrounding text. Use context clues to make educated guesses if necessary.
• Be cautious with synonyms: The information in the passage may be paraphrased or expressed using synonyms. Stay alert for variations of keywords or terms that convey the same meaning.

Check More IELTS Reading Answers

Practice ielts reading based on question types.

Start Preparing for IELTS: Get Your 10-Day Study Plan Today!

Kasturika Samanta

Kasturika is a professional Content Writer with over three years of experience as an English language teacher. Her understanding of English language requirements, as set by foreign universities, is enriched by her interactions with students and educators. Her work is a fusion of extensive knowledge of SEO practices and up-to-date guidelines. This enables her to produce content that not only informs but also engages IELTS aspirants. Her passion for exploring new horizons has driven her to achieve new heights in her learning journey.

Explore other Reading Topics

Janice Thompson

Post your Comments

Recent articles.

IELTSMaterial Master Program

1:1 Live Training with Band 9 Teachers

4.9 ( 3452 Reviews )

Our Offices

Gurgaon city scape, gurgaon bptp.

Step 1 of 3

Great going .

Get a free session from trainer

Have you taken test before?

Please select any option

Email test -->

Please enter Email ID

Mobile Band 9 trainer -->

Please enter phone number

Application

Please select any one

Already Registered?

Select a date

Please select a date

Select a time (IST Time Zone)

Please select a time

Mark Your Calendar: Free Session with Expert on

Which exam are you preparing?

Great Going!

Space travel has unexpected effects on gut health

The boundless expanse of space continues to capture our imagination, but as we venture deeper into the cosmos, we need to understand its impact on our bodies. This is becoming increasingly vital as we prepare for long-duration spaceflight.

One subject that has been recently explored in greater depth is the effects of spaceflight on gut health, and the findings are startling.

Spaceflight alters the gut

In a new study, a global consortium led by the University College Dublin (UCD), and McGill University , Canada, has shed light on how space travel impacts the gut microbiome.

Collaborating with NASA and other international partners, this research has provided the most in-depth profile to-date of the changes that occur in our gut microbes during space travel .

This fascinating study utilized cutting-edge genetic technologies to analyze changes in the gut microbiomes , colons, and livers of mice aboard the International Space Station (ISS) for three months.

The outcomes revealed significant shifts in specific bacteria and related changes in host gene expression related to immune and metabolic dysfunction commonly observed in space. This offers fresh insights into how such changes could affect astronaut physiology during prolonged missions.

Astronaut physiology and spaceflight

“Spaceflight extensively alters astronaut physiology, yet many underlying factors remain a mystery. By integrating new genomic methods, we can simultaneously explore gut bacteria and host genetics in extraordinary detail and are beginning to see patterns that could explain spaceflight pathology,” said Dr. Emmanuel Gonzalez.

“It’s clear we’re not just sending humans and animals to space, but entire ecosystems, the understanding of which is crucial to help us develop safeguards for future space exploration.”

Ireland’s role in space research

This study is a significant part of The Second Space Age: Omics, Platforms and Medicine across Space Orbits – the largest coordinated release of space biology discoveries in history. The research emphasizes Ireland’s burgeoning role in microbiome and space life sciences research.

Comprehending biological adaptations to spaceflight can boost aerospace medicine and have major implications for terrestrial health.

“These discoveries highlight the intricate dialogue between specific gut bacteria and their mouse hosts, critically involved in bile acid, cholesterol, and energy metabolism. They shed new light on the importance of microbiome symbiosis to health and how these Earth-evolved relationships may be vulnerable to the stresses of space,” said Professor Nicholas Brereton of UCD School of Biology and Environmental Science.

“We hope this research exemplifies how cooperative Open Science can drive discoveries with clear medical benefits on Earth, while also supporting upcoming Artemis missions, the deployment of the Gateway deep space station, and a crewed mission to Mars.”

Safe and effective space missions

This pioneering study is an important piece of the puzzle of understanding how spaceflight impacts astronauts.

According to Jonathan Galazka at NASA Ames Research Center, these discoveries will aid the design of safe and effective missions to Earth orbit, the Moon, and Mars.

Galazka also pointed out the importance of the collaborative nature of this project as a blueprint for how Open Science can accelerate the pace of discovery.

As we stand on the brink of a new era in space exploration, understanding the effect of spaceflight on gut health, among other physiological changes , is essential.

The insights gained from this study offer new ways of preparing astronauts for the rigors of space travel and ensuring their health and safety during their missions.

Countering the gut changes of space travel

As we continue to unravel the complexities of how spaceflight alters the human body, diet and nutrition emerge as critical components in maintaining astronaut health.

Researchers are now turning their attention to how targeted dietary interventions could mitigate the adverse effects on gut health observed during space missions.

Nutritional strategies that support a balanced gut microbiome in space are a promising area of study. By incorporating prebiotics, probiotics, and specific dietary components known to strengthen gut health, scientists aim to develop personalized nutritional plans for astronauts.

These interventions could help counteract the negative shifts in gut bacteria and associated metabolic dysfunctions revealed in the recent study.

As preparations for longer missions, such as those to Mars, accelerate, the role of nutrition in safeguarding astronaut health becomes even more critical.

The study is published in the journal npj Biofilms and Microbiomes .

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap , a free app brought to you by Eric Ralls and Earth.com.

Krasnodar Krai Travel Guide: All You Need To Know

Krasnodar Krai, often referred to as Krasnodar, is a federal subject (krai) of Russia located in the Southern Federal District. It is known for its diverse landscapes, including the Black Sea coastline, fertile farmland, and the Caucasus Mountains. The administrative center of Krasnodar Krai is the city of Krasnodar. Here’s some information about Krasnodar Krai:

Places to Visit in Krasnodar Krai: Sochi: This coastal city on the Black Sea is famous for its subtropical climate, beautiful beaches, and the host of the 2014 Winter Olympics. Visit the Sochi Arboretum, Rosa Khutor Alpine Ski Resort, and the Black Sea coast.

Krasnodar: Explore the largest city in the region, known for its parks, cultural attractions, and the Krasnodar Stadium. The Krasnodar Park and Safari Park are popular.

Anapa: A popular seaside resort town with sandy beaches, historical sites, and a mild climate.

Caucasus Mountains: Hike and explore the stunning landscapes of the Caucasus Mountains, including the Sochi National Park and Krasnaya Polyana.

Adler: A city near Sochi, known for its beautiful beachfront and proximity to the Adler Arena Skating Center.

Abrau-Dyurso: Visit the famous Abrau-Dyurso wine estate, known for its sparkling wines, and enjoy wine tasting.

Best Time to Visit Krasnodar Krai: Summer (June to August): The summer months are ideal for visiting Krasnodar Krai, especially the coastal areas, as the weather is warm and beach activities are in full swing.

Spring and Early Autumn: Spring (April to May) and early autumn (September to October) are also pleasant, with milder temperatures and fewer crowds.

Things to Do in Krasnodar Krai: Beach Activities: Enjoy swimming, sunbathing, water sports, and beachfront promenades along the Black Sea coast.

Outdoor Adventures: Explore the natural beauty of the region, including hiking, mountain biking, and winter sports in the Caucasus Mountains.

Cultural Exploration: Discover local traditions, museums, and historical sites to learn about the region’s rich heritage.

Wine Tasting: Visit vineyards and wineries in the region to sample local wines.

How to Get Around Krasnodar Krai: Public Transportation: Public buses, trams, and trolleybuses serve the major cities in Krasnodar Krai. Sochi, Krasnodar, and Anapa have well-developed public transportation networks.

Taxis: Taxis are readily available and can be used for short trips within the cities and for transportation to more remote areas.

Car Rental: Renting a car can be a convenient option for exploring the region, especially if you plan to visit various locations.

Domestic Flights: Major cities like Sochi and Krasnodar have airports with domestic flights connecting them to other Russian cities.

Where to Eat in Krasnodar Krai: Local Cuisine: Savor traditional Russian and Caucasian dishes, including shashlik (kebabs), borscht (beet soup), and local seafood in coastal areas.

Cafes and Restaurants: Explore cafes and restaurants offering international cuisine, including European, Asian, and Middle Eastern dishes.

Street Food: Try local snacks and street food from vendors in markets and along popular tourist areas.

Where to Stay in Krasnodar Krai: Krasnodar Krai offers a range of accommodation options, including hotels, guesthouses, hostels, and resorts. The coastal cities, such as Sochi and Adler, have a variety of lodging choices to suit different budgets and preferences.

Travel Tips for Krasnodar Krai: Language: Russian is the primary language spoken in Krasnodar Krai, so having some knowledge of the language can be helpful, especially in more remote areas.

Currency: The currency used in Krasnodar Krai is the Russian Ruble (RUB). Credit cards are widely accepted in hotels and restaurants, but it’s a good idea to carry cash for smaller establishments and markets.

Safety: Krasnodar Krai is generally safe for tourists, but, like in any travel, be cautious with your belongings and personal safety.

Climate: The climate in the coastal areas is milder compared to the mountainous regions. Be prepared for seasonal temperature variations.

Local Customs: Be respectful of local customs and traditions, particularly when visiting cultural or religious sites.

Transportation: Familiarize yourself with the local transportation system, and consider using taxis or ridesharing apps for convenience.

Krasnodar Krai offers a mix of natural beauty, cultural experiences, and outdoor adventures. By following these travel tips, you can have a memorable and enjoyable visit to this diverse and scenic region in southern Russia.

You might also enjoy:

Exploring petnjica: a hidden gem in montenegro, changchun travel guide: all you need to know.

Best Travel Insurances in 2022 covering COVID-19

Gansu travel guide: all you need to know, leave a comment cancel reply.

Your email address will not be published. Required fields are marked *

Save my name, email, and website in this browser for the next time I comment.

Ukraine war latest: Zelenskyy reveals plan after Kursk invasion; more than 50 killed in double missile strike

Two missiles have killed more than 50 people and injured hundreds in a city in central Ukraine, one of the deadliest attacks by Russia since the invasion of Ukraine. Meanwhile, Volodymyr Zelenskyy has spoken about his intentions after Kyiv launched an incursion into Russia last month.

Tuesday 3 September 2024 22:57, UK

• Missiles kill more than 50 people in double strike on Ukrainian city
• 'Russian scum will pay,' Zelenskyy vows
• Video shows damage left by deadly attack
• Mongolia explains why Putin was not arrested
• Ukraine plans to indefinitely hold seized territory in Russia, Zelenskyy says  
• Watch: Zelenskyy discusses Kursk invasion in TV interview
• Big picture: Everything you need to know on the war this week
• Live reporting by Katie Williams

Expert view

• Dominic Waghorn: Putin rubbing salt in wounds as Kyiv pleads for long-range attacks
• Sean Bell: Strike proves Putin's priority is on Ukraine, not incursion into Russia

That brings an end to our live coverage of the Ukraine war for this evening.

We'll be back with any major developments overnight and our rolling updates will continue soon.

Before we go, here's a reminder of the day's key events:

• Ukrainian authorities said at least 51 people were killed and more than 200 injured in a Russian ballistic missile attack on the central city of Poltava. The missiles hit a military academy and a nearby hospital, officials said;
• Three days of mourning were declared by Poltava regional head Philip Pronin after one of the deadliest attacks of the war;
• Moldova's government said its energy dependence on Russia made it difficult to heed a requirement by the International Criminal Court  to arrest Vladimir Putin  as he visited the country.
• Meanwhile, several government ministers resigned and the deputy head of the Ukrainian president's office was sacked ahead of an expected government reshuffle;
• And Volodymyr Zelenskyy told NBC News in an exclusive interview that Ukraine planned to indefinitely hold territory seized in its shock invasion of Kursk last month as part of a plan to force Mr Putin to the negotiating table.

Washington plans to send more military aid to Ukraine in the coming weeks, the White House has said.

National security spokesperson John Kirby told a briefing that the US's support for Kyiv remains "unshakeable" and it was focused on strengthening Ukraine's military and defences against Russian attacks.

He noted that the US recently announced another drawdown of military assistance - and said it intends to send another round of aid in the coming weeks.

Mongolia ignored the International Criminal Court's arrest warrant for Vladimir Putin as it rolled out the red carpet to receive him today.

The Russian president should, in theory, have been handcuffed as he arrived - but the Mongolian government said earlier that it was difficult to arrest him due to the country's position of energy dependence on Moscow (see 17.35 post).

Mr Putin was welcomed in the main square of Ulaanbaatar by an honour guard as a crowd of people watched behind temporary barriers.

He and Mongolian leader Ukhnaa Khurelsukh later laid a wreath at a monument to Soviet Marshal Georgy Zhukov, visited a school curated by a Russian economic university and attended a reception ceremony where Mr Putin gave a toast.

Russia has launched another attack on Ukraine, officials have said, less than a day after its deadly ballistic missile strike killed more than 50 people in Poltava.

The regional administration of the northeastern Sumy region said Russian forces launched an airstrike on Sumy city tonight, hitting one of its university buildings.

It said a guided bomb was believed to have been used in the attack. There were no details of any casualties.

"All necessary services are available on site," the administration said in a post to Telegram .

We reported earlier on Voldymyr Zelenskyy's comments that Ukraine plans to indefinitely hold territory it has seized in its Kursk invasion (see 18.17 post).

Asked about the surprise invasion in an interview with our US partner network   NBC News , Mr Zelenskyy said the operation was aimed at restoring Ukraine's "territorial integrity".

He also said Kyiv did not "need" Russian land - but he remained silent on what the next steps would be.

Watch a clip from the interview here...

People are still trapped under the rubble of a building destroyed by a Russian attack in Poltava, Volodymyr Zelenskyy has said.

Rescue efforts are ongoing and rubble is still being cleared, he said in his nightly address.

The Ukrainian president confirmed at least 51 people have died and 271 are injured as a result of one of the deadliest attacks of the war so far.

"I am grateful to all the rescuers, doctors, medical nurses and all the Poltava residents who have joined in to help, donated blood, and who provide support," he said.

"We know that there are people under the rubble of the destroyed building. Everything is being done to save as many lives as possible."

Volodymyr Zelenskyy has posted a video of his meeting with the UN's nuclear chief Rafael Mariano Grossi in Kyiv today.

Mr Grossi, director-general of the International Atomic Energy Agency, met the Ukrainian president ahead of his visit to the Zaporizhzhia power plant, where he said the situation was "very fragile".

"The station is again on the verge of being on a blackout. We've had eight of those in the past. A blackout [means] no power; no power, no cooling. No cooling, then maybe you have a disaster," he told reporters before the meeting.

Mr Zelenskyy said his talks with Mr Grossi were focused "on the issue of strengthening nuclear safety in Ukraine, ensuring constant monitoring not only of the state of NPPs (nuclear power plants), but also of substations that are critical for their operation".

Russia has launched a new military-focused school course as it looks to prepare teenagers "mentally and physically" for service, the UK Ministry of Defence has said.

In its latest intelligence update, the ministry said the course for 15 to 18-year-olds is part of a new programme called "Foundations of Security and Defence of the Motherland".

Over 11 modules, students will cover a range of topics including "combined arms combat and small arms familiarisation", it said.

"The programme seeks to create and will likely result in a more militarised and security focused society," the MoD said.

It added that the new youth strategy in Russia was aimed primarily at preparing "pre-conscription age teenagers mentally and physically for military service".

Russia has also increased the number of summer camps for children which involve various military activities, according to the MoD.

Volodymyr Zelenskyy has dismissed the deputy head of the Ukrainian president's office, Rostyslav Shurma, according to a decree on the presidential website.

Ukrainian media outlets had been reporting that the dismissal of Mr Shurma, who took up the role in November 2021, was being considered by parliament.

The decree does not explain why he was sacked.

Meanwhile, Olha Stefanishyna, Ukraine's deputy prime minister responsible for European integration, has resigned, according to Ukraine's parliamentary speaker.

Her resignation comes after Ukraine's strategic industries, justice and environment ministers also tendered their resignation earlier today (see 15.37 post).

An expected shakeup of Ukraine's government comes at a critical time during the war with Russia, and ahead of Mr Zelenskyy's visited to the US this month where he hopes to present a "victory plan" to Joe Biden.

The Ukrainian president said changes were being undertaken to ensure Ukraine had the strengthened government it needed. 

"Autumn will be extremely important. Our state institutions must be structured in such a way so that Ukraine can achieve all the results it needs," he said.

"For this, we must strengthen some areas of the government and changes in its makeup have been prepared. There will also be changes in the (president's) office." 

A volunteer has recalled how he knew "something evil" had happened as he heard the explosions caused by Russia's missile strike on Poltava today.

Yevheniy Zemskyy, who headed to the area of the attack to offer help, said: "I heard explosions... I was at home at that time. When I left the house, I realized that it was something evil and something bad, I was scared."

Mr Zemskyy said he was worried about the children and other residents of the city.

"That's why we are here today to help our city in any way we can," he said.

According to the prosecutor general's office of Ukraine, at least 51 people were killed in the ballistic missile strike by Russian forces earlier this afternoon. More than 200 people have been injured.

Regional head Philip Pronin called the attack  "a great tragedy" and announced three days of mourning starting tomorrow.

Be the first to get Breaking News

Install the Sky News app for free