space travel engine

NASA engine capable of travelling at nearly the speed of light detailed in new report

As more countries join the race to explore space, a NASA scientist has revealed a new propulsion method that could give his agency the edge.

‘Moon is made of gas’: Embarrassing fail

TV station accidentally airs man’s testicles

Musk’s latest Aussie space passenger

A NASA scientist has cooked up plans for a bonkers new rocket engine that can reach close to the speed of light — without using any fuel.

Travelling at such speeds, the theoretical machine could carry astronauts to Mars in less than 13 minutes, or to the Moon in just over a second.

However, the real purpose of the so-called “helical engine” would be to travel to distant stars far quicker than any existing tech, according to NASA engineer Dr David Burns.

Dr Burns, from NASA’s Marshall Space Flight Centre in Alabama, unveiled the idea in a head-spinning paper posted to NASA’s website.

“This in-space engine could be used for long-term satellite station-keeping without refuelling,” Dr Burns writes in his paper .

“It could also propel spacecraft across interstellar distances, reaching close to the speed of light.”

RELATED: Humans ‘not prepared’ for alien bombshell

Travelling at these speeds, light would struggle to keep up with you, warping your vision in bizarre ways.

Everything behind you would appear black, and time would appear to stop altogether, with clocks slowing down to a crawl and planets seemingly ceasing to spin.

Dr Burns’ mad idea is revolutionary because it does away with rocket fuel altogether.

Today’s rockets, like those built by NASA and SpaceX, would need tonnes of propellants like liquid hydrogen to carry people to Mars and beyond.

The problem is, the more fuel you stick on the craft, the heavier it is. Modern propellant tanks are far too bulky to take on interstellar flights.

The helical engine gets around this using hi-tech particle accelerators like those found in Europe’s Large Hadron Collider.

Tiny particles are fired at high speed using electromagnets, recycled back around the engine, and fired again.

Using a loophole in the laws of physics, the engine could theoretically reach speeds of around 297 million metres per second, according to Dr Burns.

The contraption is just a concept for now, and it’s not clear if it would actually work.

“If someone says it doesn’t work, I’ll be the first to say, it was worth a shot,” Dr Burns told New Scientist .

“You have to be prepared to be embarrassed. It is very difficult to invent something that is new under the sun and actually works.”

In its simplest terms, the engine works by taking advantage of how mass changes at the speed of light.

In his paper, Dr Burns provides a concept to break this down that describes a ring inside a box, attached to each end by a spring.

When the ring is sprung in one direction, the box recoils in the other, as is described by Newton’s laws of motion: Every action must have an equal and opposite reaction.

“When the ring reaches the end of the box, it will bounce backwards, and the box’s recoil direction will switch too,” New Scientist explains.

However, if the box and the ring are travelling at the speed of light, things work a little differently.

At such speeds, according to Albert Einstein’s theory of relativity, as the ring approaches the end of the box it will increase in mass.

This means it will hit harder when it reaches the end of the box, resulting in forward momentum.

The engine itself will achieve a similar feat using a particle accelerator and ion particles, but that’s the general gist.

RELATED: Space race as HQ falls behind schedule

“Chemical, nuclear and electric propulsion systems produce thrust by accelerating and expelling propellants,” Dr Burns writes in his paper.

“Deep space travel is often a trade-off between thrust and large propellant storage tanks that eventually limit performance.

“The objective of this paper is to introduce and examine a unique engine that uses a closed-cycle propellant.”

The design is capable of producing a thrust up to 99 per cent the speed of light without breaking Einstein’s theory of relativity, according to Dr Burns.

However, the plan does breach Newton’s law of motion — violating the laws of physics.

That’s not the only thing holding the helical engine back: Dr Burns reckoned it would have to be 198 metres long and 12 metres wide to work.

The gizmo would also only operate effectively in the frictionless environment of deep space.

It may sound like a harebrained scheme, but engine concepts that do away with rocket fuel have been proposed before.

They include the EM drive, a machine that could theoretically generate rocket thrust using rays of light. The idea was later proved impossible.

“I know that it risks being right up there with the EM drive and cold fusion,” Dr Burns told New Scientist .

This article originally appeared on The Sun and was reproduced with permission

Add your comment to this story

To join the conversation, please log in. Don't have an account? Register

Join the conversation, you are commenting as Logout

A politician has gone viral for a very unusual act during the recent eclipse.

A news outlet has been ridiculed after it aired a man’s testicles while presenting viewer-submitted footage of Monday’s solar eclipse.

Australia’s fastest growing company has made an appearance on the passenger list of Elon Musk’s latest space launch.

Universe simulator

SpaceEngine is a realistic virtual Universe you can explore on your computer. You can travel from star to star, from galaxy to galaxy, landing on any planet, moon, or asteroid with the ability to explore its alien landscape. You can alter the speed of time and observe any celestial phenomena you please. All transitions are completely seamless, and this virtual universe has a size of billions of light-years across and contains trillions upon trillions of planetary systems. The procedural generation is based on real scientific knowledge, so SpaceEngine depicts the universe the way it is thought to be by modern science. Real celestial objects are also present if you want to visit them, including the planets and moons of our Solar system, thousands of nearby stars with newly discovered exoplanets, and thousands of galaxies that are currently known.

Cosmographic's Second Anniversary

Author: Alexander T. Long, CEO Yesterday we celebrated our second year as a studio! A lot has happened in the last year, and we have plans for even mo...

Update 0.990.46.2000: Catalog Update and Bug Fixes

Author: Dr. Megan Tannock Today’s update includes several smaller updates to several SpaceEngine features. The first is a major exoplanet catalog ex...

Update 0.990.46.1990: Climate Model Update Full Release

Recently, we announced the addition of a Climate Model to SpaceEngine, which introduced global temperature maps, local pressures, local densities, win...

All types of celestial objects

represented

Galaxies, nebulae, stars and star clusters, planets and moons, comets and asteroids

Thousands of known

celestial objects

Known galaxies, stars, planets, asteroids, nebulae are represented using catalogs: HIPPARCOS, NGC/IC, Messier, MPC, NASA Exoplanet Archive and many others

procedural generation

for uncharted regions

Uncharted regions of space feature procedurally generated objects: galaxies, stars, star clusters, nebulae and planetary systems

Incredibly huge

and realistic Universe

Trillions of galaxies with billions of star systems in each, everything is realistically scaled

free to move

around the universe

Seamless transition from the surface of a planet to the most distant galaxies, and free game-like movement with the WASD keys

Easy navigation

many useful tools

Click on any visible object with the mouse and hit the 'G' key to fly directly to it. Search for objects by name, search by parameters within a certain radius, browse an interactive map of the surrounding space and view a map of the current planetary system

Save locations

and name objects

Save a favorite point in space and time and share it with friend. Give a name to any discovered planet, star or galaxy, and write a description for it.

Observe the Universe

Accelerate, decelerate, or reverse the flow of time to see the orbital motion of planets and moons, and watch sunsets and eclipses

Tools to learn

how the Universe works

Read detailed physical and astronomical data of any celestial body using the built-in Wiki system. Look at the orbital path lines of planets and moons, and compare their size side-by-side

3D landscapes on planets

volumetric galaxies and nebulae

Solar System bodies have real terrain models obtained by space probes; realistic hi-detail terrain on procedural planets

Photorealistic

Photorealistic lighting and atmospheric model

Space ships

with realistic orbital mechanics

Pilot star ships with realistic orbital mechanics, Alcubierre warp drives, and aerodynamics in planetary atmospheres

Multilanguage

Localization in 20 languages, with a simple system for creating new translations

Huge modding

Import space ship models, planetary surface textures and terrain, astronomical catalogs, and more

And much more

Movement made possible with free, spacecraft or aircraft mode

``Select and fly`` autopilot to automatically go directly to the object

Automatic binding of the observer to moving objects

Automatic selection of optimum flight speed

Built-in wiki system with descriptions and ability to extend

Ability to import user addons: models, textures, catalogs

3D models of galaxies and nebulae with interstellar dust clouds

Accurate planetary atmosphere models

Controllable space ships

Original music with context-dependent track switching

Localization in many languages, with the ability to add new ones

• CPU: Intel Core i3-3220T, AMD FX-4100
• GPU: Nvidia GeForce GTX 1050 Ti, AMD Radeon RX 460; 3+ GB dedicated video memory (VRAM)
• OS: Windows 10

Recommended

• CPU: Intel Core i5-4430, AMD FX-8350
• GPU: Nvidia GeForce GTX 1060, AMD Radeon RX 480; 5+ GB dedicated video memory (VRAM)
• OS: Windows 10/11

If you like SpaceEngine, buy the latest version on Steam , and receive free updates as we make improvements and add new features!

At the moment, we are no longer accepting donations via PayPal. If you want to support SpaceEngine beyond purchasing it for yourself, consider buying a copy for a friend or simply tell your friends and family about SpaceEngine and why you love it. No matter what you do, we deeply appreciate your support!

To revisit this article, visit My Profile, then View saved stories .

• Backchannel
• Newsletters
• WIRED Insider
• WIRED Consulting

Daniel Oberhaus

A Mythical Form of Space Propulsion Finally Gets a Real Test

Since the birth of the space age, the dream of catching a ride to another solar system has been hobbled by the “tyranny of the rocket equation ,” which sets hard limits on the speed and size of the spacecraft we sling into the cosmos. Even with today’s most powerful rocket engines, scientists estimate it would take 50,000 years to reach our closest interstellar neighbor , Alpha Centauri. If humans ever hope to see an alien sunrise , transit times will have to drop significantly.

Of the advanced propulsion concepts that could theoretically pull that off, few have generated as much excitement—and controversy—as the EmDrive. First described nearly two decades ago, the EmDrive works by converting electricity into microwaves and channeling this electromagnetic radiation through a conical chamber. In theory, the microwaves can exert force against the walls of the chamber to produce enough thrust to propel a spacecraft once it’s in space. At this point, however, the EmDrive exists only as a laboratory prototype, and it’s still unclear whether it’s able to produce thrust at all. If it does, the forces it generates aren’t strong enough to be registered by the naked eye, much less propel a spacecraft.

Over the past few years, however, a handful of research teams, including one from NASA, claim to have successfully produced thrust with an EmDrive. If true, it would amount to one of the biggest breakthroughs in the history of space exploration. The problem is that the thrust observed in these experiments is so small that it’s hard to tell if it’s real.

The resolution lies in designing a tool that can measure these minuscule amounts of thrust. So a team of physicists at Germany’s Technische Universität Dresden set out to create a device that would fill this need. Led by physicist Martin Tajmar, the SpaceDrive project aims to create an instrument so sensitive and immune to interference that it would put an end to the debate once and for all. In October, Tajmar and his team presented their second set of experimental EmDrive measurements at the International Astronautical Congress, and their results will be published in Acta Astronautica this August. Based on the results of these experiments, Tajmar says a resolution to the EmDrive saga may only be a few months away.

Many scientists and engineers dismiss the EmDrive because it appears to violate the laws of physics. Microwaves pushing on the walls of an EmDrive chamber seem to generate thrust ex nihilo, which runs afoul of the conservation of momentum—it’s all action and no reaction. Proponents of the EmDrive, in turn, have appealed to fringe interpretations of quantum mechanics to explain how the EmDrive might work without violating Newtonian physics. “From the theory point of view, no one takes this seriously,” Tajmar says. If the EmDrive is able to produce thrust, as some groups have claimed, he says they have “no clue where this thrust is coming from.” When there’s a theoretical rift of this magnitude in science, Tajmar sees only one way to close it: experimentation.

In late 2016, Tajmar and 25 other physicists gathered in Estes Park, Colorado, for the first conference dedicated to the EmDrive and related exotic propulsion systems. One of the most exciting presentations was given by Paul March, a physicist at NASA’s Eagleworks lab , where he and his colleague Harold White had been testing various EmDrive prototypes. According to March’s presentation and a subsequent paper published in the Journal of Propulsion and Power , he and White observed several dozen micro-newtons of thrust in their EmDrive prototype. (For the sake of comparison, a single SpaceX Merlin engine produces around 845,000 Newtons of thrust at sea level.) The problem for Harold and White, however, was that their experimental setup allowed for several sources of interference, so they couldn’t say for sure whether what they observed was thrust.

Tajmar and the Dresden group used a close replica of the EmDrive prototype used by Harold and White in their tests at NASA. It consists of a copper frustum—a cone with its top lopped off—that is just under a foot long. This design can be traced back to the engineer Roger Shawyer, who first described the EmDrive in 2001. During tests, the EmDrive cone is placed in a vacuum chamber. Outside the chamber, a device generates a microwave signal that gets relayed, using coaxial cables, to antennas inside the cone.

This isn’t the first time the Dresden team has sought to measure nearly imperceptible amounts of force. They built similar contraptions for their work on ion thrusters, which are used to precisely position satellites in space. These micro-newton thrusters are the kind that were used by the LISA Pathfinder mission, which needs extremely precise positioning ability to detect faint phenomena like gravitational waves. But to study the EmDrive and similar propellantless propulsion systems, Tajmar says, required nano-newton resolution.

Their approach was to use a torsion balance, a pendulum-type balance that measures the amount of torque applied to the axis of the pendulum. A less sensitive version of this balance was also used by the NASA team when they thought their EmDrive produced thrust. To accurately gauge the small amount of force, the Dresden team used a laser interferometer to measure the physical displacement of the balance scales produced by the EmDrive. According to Tajmar, their torsion scale has a nano-newton resolution and supports thrusters weighing several pounds, making it the most sensitive thrust balance in existence.

Dell Cameron

Andy Greenberg

Rhett Allain

Ryan Waniata

But a really sensitive thrust balance isn’t much use unless you can also determine whether the detected force is in fact thrust and not an artifact of outside interference. And there are plenty of alternate explanations for Harold and White’s observations. To determine whether an EmDrive actually produces thrust, researchers must be able to shield the device from interference caused by the Earth's magnetic poles, seismic vibrations from the environment, and the thermal expansion of the EmDrive due to heating from the microwaves.

Tweaks to the design of the torsion balance—to better control the EmDrive's power supply and shield it from magnetic fields—took care of some of the interference issues, Tajmar says. A more difficult problem was how to address “thermal drift.” When power flows to the EmDrive, the copper cone heats up and expands, which shifts its center of gravity just enough to cause the torsion balance to register force that can be mistaken as thrust. Tajmar and his team hoped that changing the orientation of the thruster helped address that issue.

Over the course of 55 experiments, Tajmar and his colleagues registered an average of 3.4 micro-newtons of force from the EmDrive, which was very similar to what the NASA team found. Alas, these forces did not appear to pass the thermal drift test. The forces seen in the data were more indicative of thermal expansion than thrust.

All hope is not lost for the EmDrive, however. Tajmar and his colleagues are also developing two additional types of thrust balances, including a superconducting balance that will, among other things, help to eliminate false positives produced by thermal drift. If they detect force from an EmDrive on these balances, there’s a high probability that it is actually thrust. But if no force is registered on these balances, it likely means that all the previous EmDrive thrust observations were false positives. Tajmar says he hopes to have a final verdict by the end of the year.

But even a negative result from that work might not kill the EmDrive for good. There are many other propellantless propulsion designs to pursue. And if scientists ever do develop new forms of weak propulsion, the hyper-sensitive thrust balances developed by Tajmar and the Dresden team will almost certainly play a role in sorting science fact from science fiction.

• My glorious, boring, almost-disconnected walk in Japan
• What do Amazon's star ratings really mean?
• Drugs that boost circadian rhythms could save our lives
• The 4 best password managers to secure your digital life
• What tech companies pay employees in 2019
• 🏃🏽‍♀️ Want the best tools to get healthy? Check out our Gear team's picks for the best fitness trackers , running gear (including shoes and socks ), and best headphones .
• 📩 Get even more of our inside scoops with our weekly Backchannel newsletter

Sabrina Weiss

Stephen Clark, Ars Technica

Reece Rogers

Ben Brubaker

R Douglas Fields

• April 11, 2024 | Powering the Future: Unbiased PEC Cells Achieve Unprecedented Efficiency
• April 11, 2024 | Neuroscience Breakthrough Unveils How We Learn and Remember
• April 11, 2024 | Salty Secrets: NASA Decodes El Niño’s Coastal Impact
• April 11, 2024 | Webb Telescope Uncovers Neutron Star Hidden in Supernova Debris
• April 11, 2024 | How Our Brains Work: Connecting Lab-Grown Brain Cells Yields New Insights

Prometheus Ignites: Future of Space Travel With Reusable Rockets

By European Space Agency (ESA) June 30, 2023

Prometheus full ignition, ArianeGroup test center in Vernon, France on June 22, 2023. The Prometheus engine, designed with a thrust capacity of 100 tonnes, uses innovative materials and manufacturing techniques such as 3D printing to cut its costs down to one-tenth of its predecessor, the Ariane 5’s Vulcain 2. Prometheus operates on a clean-burning, liquid oxygen-liquid methane fuel to simplify handling and enhance reusability. Furthermore, the engine is mounted on a reusable rocket stage prototype, Themis, and will undergo a series of hop-tests to evaluate flight and landing capabilities. Credit: ArianeGroup

Progressing with the development of reusable European rockets, ArianeGroup successfully tested Prometheus, a 100-tonne thrust class engine that uses liquid oxygen-liquid methane fuel and 3D printing for cost-effective, clean, and reusable operations. Mounted on a prototype reusable rocket stage, Themis, the engine is set for further tests to assess flight and landing capabilities and is expected to be a central element in future European launchers.

Work to develop a reusable engine for European rockets is progressing, with full ignition of an early prototype of Prometheus. These images were taken on June 22, 2023, at ArianeGroup’s test facility in Vernon, France during a 12-second burn. 

The 100-tonne thrust class Prometheus features extensive use of new materials and manufacturing techniques designed to reduce its cost to just a tenth of Ariane 5’s Vulcain 2, an upgraded version of which – Vulcain 2.1 – powers the core stage of Ariane 6. 

Prometheus burns liquid oxygen-liquid methane fuel. Methane is clean burning and simplifies handling, to help enable reusability and reduce the cost of ground operations before and after flight.

Prometheus features variable thrust and multiple ignition capabilities. Additive layer manufacturing – so-called 3D printing – features extensively, reducing the number of parts, speeding up production, and reducing waste. 

For the Vernon and Lampoldshausen tests, Prometheus is mounted in a prototype of a reusable rocket stage, called Themis, which is being developed in parallel with the engine. Later, this engine-stage combination will attempt a series of “hop-tests,” lifting a few meters above the ground to check flight and landing capability. 

Together, Prometheus and Themis are envisioned to be common technological building blocks for a future family of European launchers. 

More on SciTechDaily

Fired Up: A Look at the 55 Engines and Motors That Power NASA’s Artemis Mission

NASA’s THEMIS Mission Tracks Space Weather & the Magnetosphere

Progress Underway on NASA Space Launch System (SLS) Moon Rockets for Artemis II, III, and IV

NASA at Your Table: Where Food Meets Methane and the Greenhouse Effect

NASA Upgrades Powerful SLS Rocket Engines – Production Restarted for Next Era of Space Exploration

Cassini Spacecraft Gets Close-Up of Saturn’s Moon Prometheus

Neutronic Engine: New Engine Capability Accelerates Advanced Vehicle Research

Mystery of auroral beads uncovered with nasa’s themis spacecraft, 3 comments on "prometheus ignites: future of space travel with reusable rockets".

What a rubbish headline. Igniting the future of reusable rockets …. You dumb f***s, spacex beat everyone to the punch. End of. Give Elon the credit he deserves. The only currently available reusable rockets courtesy of Musk. Not Bezos, or rocket lab or any of the government agencies. Musk and musk along done it and proved the concept. 10 fucking years ago. That’s a decade for any ret***s that can’t count.

It seems that if the Americans did something good already, we Europeans are to ignore it? Pretend it doesn’t exist? Understood. Carry on.

I have reservations about the article or blog titled “Prometheus Ignites: Future of Space Travel With Reusable Rockets” by the European Space Agency (ESA) published on June 30, 2023. Firstly, it fails to acknowledge the existing successful reusable rocket technologies employed by companies such as SpaceX and Blue Origin. These companies have clearly demonstrated the viability and economic benefits of reusability. Ignoring their contributions creates a misleading impression that the European Space Agency is a pioneer in this field, which is far from accurate. It is important to acknowledge and credit the efforts of SpaceX, who have played a crucial role in driving the entire rocketry and space industry towards sustainable and reusable rocket technology.

In order to provide a comprehensive and balanced perspective, the article or blog should have acknowledged the significant achievements made by SpaceX and Blue Origin in the realm of reusable rockets. These companies have made remarkable progress, not only in developing reusable launch vehicles but also in successfully landing and relaunching them. Their breakthroughs have paved the way for a paradigm shift in space travel and have inspired other organizations, including the European Space Agency, to explore similar concepts. Recognizing the contributions of SpaceX and Blue Origin would have highlighted the collaborative nature of scientific and technological advancements in the space industry.

It is essential for articles or blogs discussing advancements in space travel to give credit where it is due, particularly to those who have made substantial contributions. By acknowledging the pioneering efforts of SpaceX, the European Space Agency’s article or blog would have provided a more accurate representation of the progress in reusable rocket technology. Such recognition would foster a spirit of collaboration and encourage further innovation in the industry, benefiting all stakeholders involved in the pursuit of sustainable and cost-effective space exploration.

Leave a comment Cancel reply

Email address is optional. If provided, your email will not be published or shared.

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

An illustration shows what an EmDrive looks like.

NASA's 'Impossible' Space Engine Tested—Here Are the Results

The first independent tests of the EmDrive suggest there's a mundane explanation for the wildly controversial device.

Spaceflight is hard. Blasting heavy cargo, spacecraft, and maybe people to respectable speeds over interplanetary distances (not to mention the luxury of stopping at destinations) requires an amount of propellant too massive for current rockets to haul into the void.

That is, unless you have an engine that can generate thrust without fuel .

It sounds impossible, but scientists at NASA’s Eagleworks Laboratories have been building and testing just such a thing. Called an EmDrive, the physics-defying contraption ostensibly produces thrust simply by bouncing microwaves around inside a closed, cone-shaped cavity, no fuel required.

It would be a bit like Han Solo flying the Millennium Falcon just by head-butting the dashboard, and if you think that sounds controversial, you’re right.

The device last made headlines in late 2016 when a leaked study reported the results of the latest round of NASA testing. Now, independent researchers in Germany have built their own EmDrive, with the goal of testing innovative propulsion concepts and determining whether their seeming success is real or an artifact.

So, what did they find?

The NASA Eagleworks EmDrive sits inside a test chamber.

“The ‘thrust’ is not coming from the EmDrive, but from some electromagnetic interaction,” the team reports in a proceeding for a recent conference on space propulsion .

The group, led by Martin Tajmar of the Technische Universität Dresden, tested the drive in a vacuum chamber with a variety of sensors and automated gizmos attached. Researchers could control for vibrations, thermal fluctuations, resonances, and other potential sources of thrust, but they weren’t quite able to shield the device against the effects of Earth’s own magnetic field.

When they turned on the system but dampened the power going to the actual drive so essentially no microwaves were bouncing around, the EmDrive still managed to produce thrust—something it should not have done if it works the way the NASA team claims.

The researchers have tentatively concluded that the effect they measured is the result of Earth’s magnetic field interacting with power cables in the chamber, a result that other experts agree with.

“In the EmDrive case, interactions with the Earth's magnetic field seems to be the leading candidate explanation of the small thrusts seen,” says Jim Woodward of California State University, Fullerton.Woodward has theorized a propulsive device of his own called the Mach Effect Thruster, which the Dresden group also tested.

To determine what’s going on with the EmDrive, though, the group needs to enclose the device in a shield made of something called mu metals, which will insulate it against the planet’s magnetism. Importantly, this kind of shield was not part of Eagleworks’ original testing apparatus either, which suggests the original findings could also be a consequence of leaking magnetic fields.

That sounds like a blow to the concept of the EmDrive, but Woodward is not ready to close the case on the contraption just yet. Aside from the lack of mu metal shielding, the Dresden lab’s tests were run at very low power levels, meaning that “any real signal would likely be swamped by noise from spurious sources,” he says.

So, perhaps an even more powerful test is what the space doctors ordered to help settle the debate.

FREE BONUS ISSUE

Related topics.

• SPACE EXPLORATION

You May Also Like

U.S. returns to the moon as NASA's Odysseus successfully touches down

Why go back to the moon? NASA’s Artemis program has even bigger ambitions

NASA sent a map to space to help aliens find Earth. Now it needs an update.

Exclusive: Here’s What It’s Like to Spend a Year in Space

Humans are about to explore a metal-rich asteroid for the first time. Here's why.

• Environment
• Paid Content

History & Culture

• History & Culture
• History Magazine
• Gory Details
• 2023 in Review
• Mind, Body, Wonder
• Terms of Use
• Privacy Policy
• Your US State Privacy Rights
• Children's Online Privacy Policy
• Interest-Based Ads
• About Nielsen Measurement
• Do Not Sell or Share My Personal Information
• Nat Geo Home
• Attend a Live Event
• Book a Trip
• Inspire Your Kids
• Shop Nat Geo
• Visit the D.C. Museum
• Learn About Our Impact
• Support Our Mission
• Advertise With Us
• Customer Service
• Renew Subscription
• Manage Your Subscription
• Work at Nat Geo
• Sign Up for Our Newsletters
• Contribute to Protect the Planet

Copyright © 1996-2015 National Geographic Society Copyright © 2015-2024 National Geographic Partners, LLC. All rights reserved

The Nuclear Thermal Rocket That Could Get Us to Mars in Just 45 Days

The path to higher thrust propulsion starts here.

• NASA has hired Lockheed Martin to design, build, and test a nuclear-powered rocket for space travel.
• The technology could speed up a manned trip to Mars from the current seven-month minimum to as few as 45 days.
• A nuclear fission reactor would power the rocket’s engine for nuclear propulsion.

NASA and the U.S. Department of Defense’s Defense Advanced Research Projects Agency (DARPA) contracted Lockheed Martin to design, build, and test nuclear thermal rocket technology for a shorter, faster trip to the Red Planet. The rocket is also expected to operate with twice the efficiency as conventional chemical rockets, which combine fuel and an oxidizer for combustion power.

“Working with DARPA and companies across the commercial space industry will enable us to accelerate the technology development we need to send humans to Mars,” Pam Melroy, NASA deputy administrator, says in a statement . “This demonstration will be a crucial step in meeting our Moon-to-Mars objectives for crew transportation into deep space.”

Lockheed Martin will lead spacecraft design, integration, and testing of the roughly $500 million project, and BWX Technologies will design and build the nuclear fission reactor to power the engine.

Tabitha Dodson, DARPA program manager for the project, says in a statement that the DRACO project (Demonstration Rocket for Agile Cislunar Operations) “aims to give the nation leap-ahead propulsion capability.”

A nuclear thermal rocket could achieve high thrust—much like chemical propulsion—but is up to three times more efficient. This means that instead of the seven month-minimum it now takes to get to Mars , a nuclear-powered trip would only take 45 days . And going to Mars in 45 days isn’t the only benefit, as NASA is also looking for an efficient Earth-to-Moon connection.

“In order for our country, for our species, to further explore space, we need changes in more efficient propulsion,” Kirk Shireman, Lockheed Martin’s vice president for lunar exploration campaign, said in a press conference, according to the Washington Post . “Higher thrust propulsion is really, really important. And I think we’re on the cusp of that here.”

The United States started down the nuclear rocket path in the 1950s, but the idea was scraped during a 1970s budget cut. The DRACO program aims to build on that early research, but with a new fuel option for fewer logistical hurdles. Using a high-assay, low-enriched uranium fuel, the fission -based reactor can split apart atoms, heat up liquid hydrogen, and shoot that high-temperature gas through an engine nozzle for the needed thrust.

The greater efficiency from a nuclear thermal rocket not only slashes transit time, but also reduces astronaut risks and cuts down on payload needs for both supplies and systems.

One challenge yet to be overcome, according to Live Science , is the need to heat the hydrogen to 4,400°F while also storing it a minus-420°F. “This is just as much a demonstration of on-orbit storage of cryogenic liquid hydrogen as it is a demo of the nuclear thermal rocket,” Dodson says.

In the hoped-for 2027 test launch, the engine’s fission reactor will stay turned off—for obvious safety reasons—until the rocket reaches its designated orbit. The U.S. Space Force will provide a launch vehicle to take the test vessel into space.

The initial DRACO test plans to send the craft at least 435 miles and no more than 1,240 miles into space. It has no planned maneuvers, and will instead allow the vehicle’s reactor to use the new fuel and collect data along the way. With a planned two months of liquid hydrogen stored on the craft, crews may also test, according to Space News , the possibility of an in-space refueling.

“We’re going to put this together,” Shireman told reporters, according to Live Science , “we’re going to fly this demonstration, gather a bunch of great data and really, we believe, usher in a new age for the United States [and] humankind, to support our space exploration mission.”

Tim Newcomb is a journalist based in the Pacific Northwest. He covers stadiums, sneakers, gear, infrastructure, and more for a variety of publications, including Popular Mechanics. His favorite interviews have included sit-downs with Roger Federer in Switzerland, Kobe Bryant in Los Angeles, and Tinker Hatfield in Portland. 

.css-cuqpxl:before{padding-right:0.3125rem;content:'//';display:inline;} Moon and Mars .css-xtujxj:before{padding-left:0.3125rem;content:'//';display:inline;}

How to View the Solar Eclipse

How a Lunar Supercollider Could Upend Physics

The Moon Is Going Nuclear

Private Company to Mine Helium-3 from the Moon

3 Moons Emerged From Around Neptune and Uranus

4 People Are Spending a Year In a Martian World.

America Has Planted Its Feet on the Moon Once More

The Strange Origin of the Hollow Moon Conspiracy

The Moon Is Shrinking Where We're Trying to Land

Rover Reveals Bizarre Shapes on Martian Surface

Ingenuity Has Made Its Final Flight on Mars.

February 1, 2009

14 min read

The Efficient Future of Deep-Space Travel--Electric Rockets

Efficient electric plasma engines are propelling the next generation of space probes to the outer solar system

By Edgar Y. Choueiri

Alone amid the cosmic blackness, NASA's Dawn space probe speeds beyond the orbit of Mars toward the asteroid belt. Launched to search for insights into the birth of the solar system, the robotic spacecraft is on its way to study the asteroids Vesta and Ceres, two of the largest remnants of the planetary embryos that collided and combined some 4.57 billion years ago to form today's planets.

But the goals of the mission are not all that make this flight notable. Dawn, which took off in September 2007, is powered by a kind of space propulsion technology that is starting to take center stage for long-distance missions a plasma rocket engine. Such engines, now being developed in several advanced forms, generate thrust by electrically producing and manipulating ionized gas propellants rather than by burning liquid or solid chemical fuels, as conventional rockets do.

Dawn's mission designers at the NASA Jet Propulsion Laboratory selected a plasma engine as the probe's rocket system because it is highly efficient, requiring only one tenth of the fuel that a chemical rocket motor would have needed to reach the asteroid belt. If project planners had chosen to install a traditional engine, the vehicle would have been able to reach either Vesta or Ceres, but not both.

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.

Indeed, electric rockets, as the engines are also known, are quickly becoming the best option for sending probes to far-off targets. Recent successes made possible by electric propulsion include a visit by NASA's Deep Space 1 vehicle to a comet, a bonus journey that was made feasible by propellant that was left over after the spacecraft had accomplished its primary goal. Plasma engines have also provided propulsion for an attempted landing on an asteroid by the Japanese Hayabusa probe, as well as a trip to the moon by the European Space Agency's SMART-1 spacecraft. In light of the technology's demonstrated advantages, deep-space mission planners in the U.S., Europe and Japan are opting to employ plasma drives for future missions that will explore the outer planets, search for extrasolar, Earth-like planets and use the void of space as a laboratory in which to study fundamental physics.

Although plasma thrusters are only now making their way into long-range spacecraft, the technology has been under development for that purpose for some time and is already used for other tasks in space.

As early as the first decade of the 20th century, rocket pioneers speculated about using electricity to power spacecraft. But the late Ernst Stuhl inger a member of Wernher von Braun's legendary team of German rocket scientists that spearheaded the U.S. space program finally turned the concept into a practical technology in the mid-1950s. A few years later engineers at the NASA Glenn Research Center (then known as Lewis) built the first operating electric rocket. That engine made a suborbital flight in 1964 onboard Space Electric Rocket Test 1, operating for half an hour before the craft fell back to Earth.

In the meantime, researchers in the former Soviet Union worked independently on concepts for electric rockets. Since the 1970s mission planners have selected the technology because it can save propellant while performing such tasks as maintaining the attitude and orbital position of telecommunications satellites in geosynchronous orbit.

The benefits afforded by plasma engines become most striking in light of the drawbacks of conventional rockets. When people imagine a ship streaking through the dark void toward a distant planet, they usually envision it trailing a long, fiery plume from its nozzles. Yet the truth is altogether different: expeditions to the outer solar system have been mostly rocketless affairs, because most of the fuel is typically expended in the first few minutes of operation, leaving the spacecraft to coast the rest of the way to its goal. True, chemical rockets do launch all spacecraft from Earth's surface and can make midcourse corrections. But they are impractical for powering deep-space explorations because they would require huge quantities of fuel too much to be lifted into orbit practically and affordably. Placing a pound (0.45 kilogram) of anything into Earth orbit costs as much as $10,000.

To achieve the necessary trajectories and high speeds for lengthy, high-precision journeys without additional fuel, many deep-space probes of the past have had to spend time often years detouring out of their way to planets or moons that provided gravitational kicks able to accel erate them in the desired direction (slingshot moves called gravity-assist maneuvers). Such circuitous flight paths limit missions to relatively small launch windows; only blasting off within a certain short time frame will ensure a precision swing past a cosmic body serving as a gravitational booster.

Even worse, after years of travel toward its destination, a vehicle with a chemical rocket motor would typically have no fuel left for braking. Such a probe would need the ability to fire its rocket so that it could slow enough to achieve orbit around its target and thus conduct extended scientific observations. Unable to brake, it would be limited to just a fleeting encounter with the object it aimed to study. Indeed, after a trip of more than nine years, New Horizons, a NASA deep-space probe launched in 2006, will get only a brief encounter of not more than a single Earth day with its ultimate object of study, the recently demoted "dwarf planet" Pluto.

For those who wonder why engineers have been unable to come up with ways to send enough chemical fuel into space to avoid such difficulties for long missions, let me clarify the immense hurdles they face. The explanation derives from what is called the rocket equation, a formula used by mission planners to calculate the mass of propellant required for a given mission. Russian scientist Konstantin E. Tsiolkovsky, one of the fathers of rocketry and spaceflight, first introduced this basic formula in 1903.

In plain English, the rocket equation states the intuitive fact that the faster you throw propellant out from a spacecraft, the less you need to execute a rocket-borne maneuver. Think of a baseball pitcher (a rocket motor) with a bucket of baseballs (propellant) standing on a skateboard (a spacecraft). The faster the pitcher flings the balls rearward (that is, the higher the exhaust speed), the faster the vehicle will be traveling in the opposite direction when the last ball is thrown or, equivalently, the fewer baseballs (less propellant) the pitcher would have to hurl to raise the skateboard's speed by a desired amount at any given time. Scientists call this incremental increase of the skateboard's velocity "delta-v."

In more specific terms, the equation relates the mass of propellant required by a rocket to carry out a particular mission in outer space to two key velocities: the velocity at which the rocket's exhaust will be ejected from the vehicle and the mission's delta-v how much the vehicle's velocity will increase as a result of the exhaust's ejection. Delta-v corresponds to the energy a craft must expend to alter its inertial motion and execute a desired space maneuver. For a given rocket technology (that is, one that produces a given rocket exhaust speed), the rocket equation translates the delta-v for a desired mission into the mass of propellant required to complete it. The delta-v metric can therefore be thought of as a kind of "price tag" of a mission, because the cost of conducting one is typically dominated by the cost of launching the needed propellant.

Conventional chemical rockets achieve only low exhaust velocities (three to four kilometers per second, or km/s). This feature alone makes them problematic to use. Also, the exponential nature of the rocket equation dictates that the fraction of the vehicle's initial mass that is composed of fuel the "propellant mass fraction" grows exponentially with delta-v. Hence, the fuel needed for the high delta-v required for a deep-space mission could take up almost all the starting mass of the spacecraft, leaving little room for anything else.

Consider a couple of examples: To travel to Mars from low-Earth orbit requires a delta-v of about 4.5 km/s. The rocket equation says that a conventional chemical rocket would require that more than two thirds of the spacecraft's mass be propellant to carry out such an interplanetary transfer. For more ambitious trips such as expeditions to the outer planets, which have delta-v requirements that range from 35 to 70 km/s chemical rockets would need to be more than 99.98 percent fuel. That configuration would leave no space for other hardware or useful payloads. As probes journey farther out into the solar system, chemical rockets become increasingly useless unless engineers can find a way to significantly raise their exhaust speeds.

So far that goal has proved very difficult to accomplish because generating ultrahigh exhaust speeds demands extremely high fuel combustion temperatures. The ability to reach the needed temperatures is limited both by the amount of energy that can be released by known chemical reactions and by the melting point of the rocket's walls.

Plasma propulsion systems, in contrast, offer much greater exhaust speeds. Instead of burning chemical fuel to generate thrust, the plasma engine accelerates plasmas clouds of electrically charged atoms or molecules to very high velocities. A plasma is produced by adding energy to a gas, for instance, by radiating it with lasers, microwaves or radio-frequency waves or by subjecting it to strong electric fields. The extra energy liberates electrons from the atoms or molecules of the gas, leaving the latter with a positive charge and the former free to move freely in the gas, which makes the ionized gas a far better electrical conductor than copper metal. Because plasmas contain charged particles, whose motion is strongly affected by electric and magnetic fields, application of electric or electromagnetic fields to a plasma can accelerate its constituents and send them out the back of a vehicle as thrust-producing exhaust. The necessary fields can be generated by electrodes and magnets, using induction by external antennas or wire coils, or by driving electric currents through the plasma.

The electric power for creating and accelerating the plasmas typically comes from solar panels that collect energy from the sun. But deep-space vehicles going past Mars must rely on nuclear power sources, because solar energy gets too weak at long distances from the sun. Today's small robotic probes use thermoelectric devices heated by the decay of a nuclear isotope, but the more ambitious missions of the future would need nuclear fission (or even fusion) reactors. Any nuclear reactor would be activated only after the vessel reached a stable orbit at a safe distance from Earth. Its fuel would be secured in an inert state during liftoff.

Three kinds of plasma propulsion systems have matured enough to be employed on long-distance missions. The one in most use and the kind powering Dawn is the ion drive.

The ion engine, one of the more successful electric propulsion concepts, traces its roots to the ideas of American rocketry pioneer Robert H. Goddard, formed when he was still a graduate student at Worcester Polytechnic Institute a century ago. Ion engines are able to achieve exhaust velocities ranging from 20 to 50 km/s [see box on next page].

In its most common incarnation, the ion engine gets its electric power from photovoltaic panels. It is a squat cylinder, not much larger than a bucket, that is set astern. Inside the bucket, xenon gas from the propellant tank flows into an ionization chamber where an electromagnetic field tears electrons off the xenon gas atoms to create a plasma. The plasma's positive ions are then extracted and accelerated to high speeds through the action of an electric field that is applied between two electrode grids. Each positive ion in the field feels the strong tug of the aft-mounted, negatively charged electrode and therefore accelerates rearward.

The positive ions in the exhaust leave a spacecraft with a net negative charge, which, if left to build up, would attract the ions back to the spacecraft, thus canceling out the thrust. To avoid this problem, an external electron source (a negative cathode or an electron gun) injects electrons into the positive flow to electrically neutralize it, which leaves the spacecraft neutral.

Dozens of ion drives are currently operating on commercial spacecraft mostly communications satellites in geosynchronous orbit for orbital "station-keeping" and attitude control. They were selected because they save millions of dollars per spacecraft by greatly shrinking the mass of propellant that would be required for chemical propulsion.

At the end of the 20th century, Deep Space 1 became the world's first spacecraft using an electric propulsion system to escape Earth's gravitation from orbit. The probe then accelerated by about 4.3 km/s, while consuming less than 74 kilograms of xenon propellant (about the mass of an untapped beer keg), to fly through the dusty tail of the comet Borrelly. This is the highest velocity increment gained via propulsion (as opposed to gravity assists) by any spacecraft to date. Dawn should soon break that record by adding 10 km/s to its velocity. Engineers at the Jet Propulsion Laboratory have recently demonstrated ion drives able to function flawlessly for more than three years of continuous operation.

A plasma rocket's performance is determined not only by the speed of the exhaust particles but also by its thrust density, which is the amount of thrust force an engine produces per unit area of its exhaust aperture. Ion engines and similar electrostatic thrusters suffer from a major shortcoming, called space-charge limitation, that severely reduces their thrust density: as the positive ions pass between the electrostatic grids in an ion engine, a positive charge inevitably builds up in this region. This buildup limits the attainable electric field to drive the acceleration.

Because of this phenomenon, Deep Space 1's ion engine produces a thrust force that is roughly equivalent to the weight of a single sheet of paper hardly the thundering rocket engine of sci-fi movies and more akin to a car that takes two days to accelerate from zero to 60 miles per hour. As long as one is willing to wait long enough (typically, many months), though, these engines can eventually attain the high delta-vs needed for distant journeys. That feat is possible because in the vacuum of space, which offers no resistance, even a tiny push, if constantly applied, will lead to high propulsion speeds.

A plasma propulsion system called the Hall thruster [see box at right] avoids the space-charge limitation and can therefore accelerate a vessel to high speeds more quickly (by way of its greater thrust density) than a comparably sized ion engine can. This technology has been gaining acceptance in the West since the early 1990s, after three decades of steady development in the former Soviet Union. The Hall thruster will soon be ready to take on long-range missions.

The system relies on a fundamental effect discovered in 1879 by Edwin H. Hall, then a physics graduate student at Johns Hopkins University. Hall showed that when electric and magnetic fields are set perpendicular to each other inside a conductor, an electric current (called the Hall current) flows in a direction that is perpendicular to both fields.

In a Hall thruster a plasma is produced when an electric discharge between an internal positive anode and a negative cathode situated outside the device tears through a neutral gas inside the device. The resulting plasma fluid is then accelerated out of the cylindrical engine by the Lorentz force, which results from the interaction of an applied radial magnetic field and an electric current (in this case, the Hall current) that flows in an azimuthal direction that is, in a circular "orbit" around the central anode. The Hall current is caused by the electron's motion in the magnetic and electric fields. Depending on the available power, exhaust velocities can range from 10 to more than 50 km/s.

This form of electric rocket avoids a space-charge buildup by accelerating the entire plasma (of both positive ions and negative electrons), with the result that its thrust density and thus its thrust force (and so its potential delta-v) is many times that of an ion engine of the same size. More than 200 Hall thrusters have been flown on satellites in Earth orbit. And it was a Hall thruster that the European Space Agency used to efficiently propel its SMART-1 spacecraft frugally to the moon.

Engineers are now trying to scale up today's rather small Hall thrusters so that they can handle higher amounts of power to generate greater exhaust speeds and thrust levels. The work also aims to extend their operating lifetimes to the multiyear durations needed for deep-space exploration.

Scientists at the Princeton Plasma Physics Laboratory have taken a step toward these goals by implanting segmented electrodes in the walls of a Hall thruster. The electrodes shape the internal electric field in a way that helps to focus the plasma into a thin exhaust beam. This design reduces the useless nonaxial component of thrust and improves the system's operating lifetime by keeping the plasma beam away from the thruster walls. German engineers have achieved similar results using specially shaped magnetic fields. Researchers at Stanford University have meanwhile shown that lining the walls with tough, synthetic-polycrystalline diamond substantially boosts the device's resistance to plasma erosion. Such improvements will eventually make Hall thrusters suitable for deep-space missions.

One way to further raise the thrust density of plasma propulsion is to increase the total amount of plasma that is accelerated in the engine. But as the plasma density in a Hall thruster is raised, electrons collide more frequently with atoms and ions, which makes it more difficult for the electrons to carry the Hall current needed for acceleration. An alternative known as the magnetoplasmadynamic thruster (MPDT) allows for a denser plasma by forgoing the Hall current in favor of a current component that is mostly aligned with the electric field [see box at left] and far less prone than the Hall current to disruption by atomic collisions.

In general, an MPDT consists of a central cathode sitting within a larger cylindrical anode. A gas, typically lithium, is pumped into the annular space between the cathode and the anode. There it is ionized by an electric current flowing radially from the cathode to the anode. This current induces an azimuthal magnetic field (one that encircles the central cathode), which interacts with the same current that induced it to generate the thrust-producing Lorentz force.

A single MPD engine about the size of an average household pail can process about a million watts of electric power from a solar or nuclear source into thrust (enough to energize more than 10,000 standard lightbulbs), which is substantially larger than the maximum power limits of ion or Hall thrusters of the same size. An MPDT can produce exhaust velocities from 15 to 60 km/s. It truly is the little engine that could.

This design also offers the advantage of throttling; its exhaust speed and thrust can be easily adjusted by varying the electric current level or the flow rate of the propellant. Throttling allows a mission planner to alter a spacecraft's engine thrust and exhaust velocity as needed to optimize its trajectory.

Intensive research on mechanisms that hamper the performance and lifetimes of MPD devices, such as electrode erosion, plasma instabilities and power dissipation in the plasma, has led to new, high-performance engines that rely on lithium and barium vapors for propellants. These elements ionize easily, yield lower internal energy losses in the plasma and help to keep the cathode cooler. The adoption of these liquid-metal propellants and an unusual cathode design that contains channels that alter how the electric current interacts with its surface has resulted in substantially less erosion of the cathode. These innovations are leading to more reliable MPDTs.

A team of academic and NASA researchers has recently completed the design of a state-of-the-art lithium-fed MPDT called 2, which could potentially drive a nuclear-powered vessel hauling heavy cargo and people to the moon and Mars as well as robotic missions to the outer planets.

Ion, Hall and MPD thrusters are but three variants of electric plasma rocket technology, albeit the most mature. During the past few decades researchers have developed many other promising related concepts to various degrees of readiness. Some are pulsed engines that operate intermittently; others run continuously. Some generate plasmas through electrode-based electric discharge; others use coil-based magnetic induction or antenna-generated radiation. The mechanisms they apply to accelerate plasmas vary as well: some use Lorentz forces; others accelerate the plasmas by entraining them in magnetically produced current sheets or in traveling electromagnetic waves. One type even aims to exhaust the plasma through invisible "rocket nozzles" composed of magnetic fields.

In all cases, plasma rockets will get up to speed more slowly than conventional rockets. And yet, in what has been called the "slower but faster paradox," they can often make their way to distant destinations more quickly by ultimately reaching higher spacecraft velocities than standard propulsion systems can using the same mass of propellant. They thus avoid time-consuming detours for gravity boosts. Much as the fabled slow and steady tortoise beats out the intermittently sprinting hare, in the marathon flights that will become increasingly common in the coming era of deep-space exploration, the tortoise wins.

So far the most advanced designs could impart a delta-v of 100 km/s much too slow to take a spacecraft to the far-off stars but plenty enough to visit the outer planets in a reasonable amount of time. One particularly exciting deep-space mission that has been proposed would return samples from Saturn's largest moon, Titan, which space scientists believe has an atmosphere that is very similar to Earth's eons ago.

A sample from Titan's surface would offer researchers a rare chance to search for signs of chemical precursors to life. The mission would be impossible with chemical propulsion. And, with no in-course propulsion, the journey would require multiple planetary gravity assists, adding more than three years to the total trip time. A probe fitted with "the little plasma engine that could" would be able to do the job in a sig nificantly shorter period.

Note: This article was originally printed with the title, "New Dawn for Electric Rockets".

Warp drives: Physicists give chances of faster-than -light space travel a boost

Associate Professor of Physics, Oklahoma State University

Disclosure statement

Mario Borunda does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

Oklahoma State University provides funding as a member of The Conversation US.

View all partners

The closest star to Earth is Proxima Centauri. It is about 4.25 light-years away, or about 25 trillion miles (40 trillion km). The fastest ever spacecraft, the now- in-space Parker Solar Probe will reach a top speed of 450,000 mph. It would take just 20 seconds to go from Los Angeles to New York City at that speed, but it would take the solar probe about 6,633 years to reach Earth’s nearest neighboring solar system.

If humanity ever wants to travel easily between stars, people will need to go faster than light. But so far, faster-than-light travel is possible only in science fiction.

In Issac Asimov’s Foundation series , humanity can travel from planet to planet, star to star or across the universe using jump drives. As a kid, I read as many of those stories as I could get my hands on. I am now a theoretical physicist and study nanotechnology, but I am still fascinated by the ways humanity could one day travel in space.

Some characters – like the astronauts in the movies “Interstellar” and “Thor” – use wormholes to travel between solar systems in seconds. Another approach – familiar to “Star Trek” fans – is warp drive technology. Warp drives are theoretically possible if still far-fetched technology. Two recent papers made headlines in March when researchers claimed to have overcome one of the many challenges that stand between the theory of warp drives and reality.

But how do these theoretical warp drives really work? And will humans be making the jump to warp speed anytime soon?

Compression and expansion

Physicists’ current understanding of spacetime comes from Albert Einstein’s theory of General Relativity . General Relativity states that space and time are fused and that nothing can travel faster than the speed of light. General relativity also describes how mass and energy warp spacetime – hefty objects like stars and black holes curve spacetime around them. This curvature is what you feel as gravity and why many spacefaring heroes worry about “getting stuck in” or “falling into” a gravity well. Early science fiction writers John Campbell and Asimov saw this warping as a way to skirt the speed limit.

What if a starship could compress space in front of it while expanding spacetime behind it? “Star Trek” took this idea and named it the warp drive.

In 1994, Miguel Alcubierre, a Mexican theoretical physicist, showed that compressing spacetime in front of the spaceship while expanding it behind was mathematically possible within the laws of General Relativity . So, what does that mean? Imagine the distance between two points is 10 meters (33 feet). If you are standing at point A and can travel one meter per second, it would take 10 seconds to get to point B. However, let’s say you could somehow compress the space between you and point B so that the interval is now just one meter. Then, moving through spacetime at your maximum speed of one meter per second, you would be able to reach point B in about one second. In theory, this approach does not contradict the laws of relativity since you are not moving faster than light in the space around you. Alcubierre showed that the warp drive from “Star Trek” was in fact theoretically possible.

Proxima Centauri here we come, right? Unfortunately, Alcubierre’s method of compressing spacetime had one problem: it requires negative energy or negative mass.

A negative energy problem

Alcubierre’s warp drive would work by creating a bubble of flat spacetime around the spaceship and curving spacetime around that bubble to reduce distances. The warp drive would require either negative mass – a theorized type of matter – or a ring of negative energy density to work. Physicists have never observed negative mass, so that leaves negative energy as the only option.

To create negative energy, a warp drive would use a huge amount of mass to create an imbalance between particles and antiparticles. For example, if an electron and an antielectron appear near the warp drive, one of the particles would get trapped by the mass and this results in an imbalance. This imbalance results in negative energy density. Alcubierre’s warp drive would use this negative energy to create the spacetime bubble.

But for a warp drive to generate enough negative energy, you would need a lot of matter. Alcubierre estimated that a warp drive with a 100-meter bubble would require the mass of the entire visible universe .

In 1999, physicist Chris Van Den Broeck showed that expanding the volume inside the bubble but keeping the surface area constant would reduce the energy requirements significantly , to just about the mass of the sun. A significant improvement, but still far beyond all practical possibilities.

A sci-fi future?

Two recent papers – one by Alexey Bobrick and Gianni Martire and another by Erik Lentz – provide solutions that seem to bring warp drives closer to reality.

Bobrick and Martire realized that by modifying spacetime within the bubble in a certain way, they could remove the need to use negative energy. This solution, though, does not produce a warp drive that can go faster than light.

[ Over 100,000 readers rely on The Conversation’s newsletter to understand the world. Sign up today .]

Independently, Lentz also proposed a solution that does not require negative energy. He used a different geometric approach to solve the equations of General Relativity, and by doing so, he found that a warp drive wouldn’t need to use negative energy. Lentz’s solution would allow the bubble to travel faster than the speed of light.

It is essential to point out that these exciting developments are mathematical models. As a physicist, I won’t fully trust models until we have experimental proof. Yet, the science of warp drives is coming into view. As a science fiction fan, I welcome all this innovative thinking. In the words of Captain Picard , things are only impossible until they are not.

• General Relativity
• Theoretical physics
• Interstellar
• Speed of light
• Albert Einstein

Faculty of Law - Academic Appointment Opportunities

Operations Manager

Senior Education Technologist

Audience Development Coordinator (fixed-term maternity cover)

Lecturer (Hindi-Urdu)

share this!

May 10, 2021

A new era of spaceflight? Promising advances in rocket propulsion

by Gareth Dorrian and Ian Whittaker, The Conversation

The US Defense Advanced Research Projects Agency (Darpa) has recently commissioned three private companies, Blue Origin, Lockheed Martin and General Atomics, to develop nuclear fission thermal rockets for use in lunar orbit.

Such a development, if flown, could usher in a new era of spaceflight. That said, it is only one of several exciting avenues in rocket propulsion . Here are some others.

Chemical rockets

The standard means of propulsion for spacecraft uses chemical rockets. There are two main types: solid fuelled (such as the solid rocket boosters on the Space Shuttle), and liquid fuelled (such as the Saturn V ).

In both cases, a chemical reaction is employed to produce a very hot, highly pressurized gas inside a combustion chamber. The engine nozzle provides the only outlet for this gas which consequently expands out of it, providing thrust.

The chemical reaction requires a fuel, such as liquid hydrogen or powdered aluminum, and an oxidiser (an agent that produces chemical reactions) such as oxygen. There are many other variables which ultimately also determine the efficiency of a rocket engine, and scientists and engineers are always looking to get more thrust and fuel efficiency out of a given design.

Recently, private company SpaceX has been conducting test flights of their Starship launcher prototype. This vehicle uses a "full-flow staged combustion (FFSC) engine," the Raptor , which burns methane for fuel and oxygen for oxidiser. Such designs were tested by the Russians in the 1960s and the US government in the 2000s, but as yet none has flown in space. The engines are much more fuel efficient and can generate a much higher thrust-to-weight ratio than traditional designs.

Fission thermal rockets

The nucleus of an atom consists of sub-atomic particles called protons and neutrons. These determine the mass of an element—the more protons and neutrons, the heavier it is. Some atomic nuclei are unstable and can be split into several smaller nuclei when bombarded with neutrons. This is the process of nuclear fission , and it can release an enormous amount of energy. As the nuclei decay, they also release more neutrons which go on to fissure more atoms—producing a chain reaction.

In a nuclear fission thermal rocket, a propellant gas, such as hydrogen, is heated by nuclear fission to high temperatures, creating a high pressure gas within the reactor chamber. Like with chemical rockets, this can only escape via the rocket nozzle, again producing thrust. Nuclear fission rockets are not envisaged to produce the kind of thrust necessary to lift large payloads from the surface of the Earth into space. Once in space though, they are much more efficient than chemical rockets—for a given mass of propellant, they can accelerate a spacecraft to much higher speeds.

Nuclear fission rockets have never been flown in space, but they have been tested on the ground. They should be able to shorten flight times between Earth and Mars from some seven months to about three months for future crewed missions. Obvious drawbacks, however, include the production of radioactive waste, and the possibility of a launch failure which could result in radioactive material being spread over a wide area.

A major engineering challenge is to sufficiently miniaturize a reactor so that it will fit on a spacecraft. There is already a burgeoning industry in the production of compact fission reactors, including the development of a fission reactor which is smaller than an adult human .

Electric propulsion

A staple of science fiction , real ion drives generate charged particles (ionization), accelerate them using electric fields and then fire them from a thruster. The propellant is a gas such as xenon, a fairly heavy element that can be easily electrically charged.

As the charged xenon atoms accelerate out of the thruster, they transfer a very small amount of momentum (the product of mass and velocity) to the spacecraft, providing gentle thrust. While slow, ion drives are among the most fuel-efficient of all spacecraft propulsion methods, so could get us further. Ion drives are commonly used for attitude control (changing which direction a spacecraft is facing) and have been considered for deorbiting old satellites .

Current ion engines are powered by solar cells , effectively making them solar powered, and requiring very little propellant. They have been used on Esa's SMART-1 mission to the Moon and Bepi-Colombo mission en-route to Mercury. Nasa are currently developing a high power electric propulsion system for the Lunar Gateway , an outpost which will orbit the Moon.

Solar sails

While propulsion usually requires propellant of some description, a more "green" method relying only on light from the Sun itself.

Sails rely on the physical property of conservation of momentum. On Earth, we are used to seeing this momentum as a dynamic pressure from air particles blowing into a sheet when sailing, propelling a vessel forwards . Light is comprised of photons , which have no mass, but they do have momentum and can transfer it to a sail. As the energies of individual photons are very small, an extremely large sail size is needed for any appreciable acceleration.

The speed gain will also depend on how far from the Sun you are. At Earth, the power received from sunlight is about 1.3 kW per square meter. If we had a sail the size of a football pitch, this would equate to 9.3 MW, providing a very low acceleration, even to a low mass object.

Solar sails have been tested by the Japanese IKAROS spacecraft which successfully flew by Venus, and the Planetary Society Lightsail-2 , which is presently in orbit around Earth.

A way of improving efficiency and reducing sail size is to use a laser to propel the spacecraft forward . Lasers produce very intense beams of photons which can be directed onto a sail to provide much higher acceleration, but would require being built in Earth orbit to avoid loss of intensity in the atmosphere. Lasers have also been proposed as a means of de-orbiting space junk—the light from the laser can slow down a piece of orbital junk, which would then fall out of orbit and burn up in the atmosphere.

The development of nuclear fission rockets may excite some and concern others. However, as private companies and national space agencies are increasingly committing to a sustained human presence in space, these alternative means of propulsion will become more mainstream and have the potential to revolutionize our nascent space-faring civilisation.

Provided by The Conversation

Explore further

Feedback to editors

Research team discovers more than 50 potentially new deep-sea species in one of the most unexplored areas of the planet

8 hours ago

New study details how starving cells hijack protein transport stations

New species of ant found pottering under the Pilbara named after Voldemort

9 hours ago

Searching for new asymmetry between matter and antimatter

Where have all the right whales gone? Researchers map population density to make predictions

Exoplanets true to size: New model calculations shows impact of star's brightness and magnetic activity

10 hours ago

Decoding the language of cells: Profiling the proteins behind cellular organelle communication

A new type of seismic sensor to detect moonquakes

Macroalgae genetics study sheds light on how seaweed became multicellular

11 hours ago

Africa's iconic flamingos threatened by rising lake levels, study shows

Relevant physicsforums posts, will we ever communicate with extraterrestial life in a reasonable time frame.

3 hours ago

Our Beautiful Universe - Photos and Videos

7 hours ago

Speed of the umbra during eclipse vs rate of the Earth's rotation

16 hours ago

Orientation of the Earth, Sun and Solar System in the Milky Way

Apr 11, 2024

What is the actual shape of black holes?

Apr 10, 2024

Increase frequency of solar eclipses

More from Astronomy and Astrophysics

Related Stories

To safely explore the solar system and beyond, spaceships need to go faster—nuclear-powered rockets may be the answer

May 20, 2020

SpaceX vs NASA: Who will get us to the moon first? Here's how their latest rockets compare

Jan 29, 2021

Earth to Mars in 100 days: The power of nuclear rockets

Jul 1, 2019

Flight by Light: Mission accomplished for LightSail 2

Aug 1, 2019

A CubeSat will test out water as a propulsion system

Jan 27, 2021

NASA Reignites Program for Nuclear Thermal Rockets

Aug 14, 2017

Recommended for you

NASA unveils probe bound for Jupiter's possibly life-sustaining moon

18 hours ago

A total solar eclipse races across North America as clouds part along totality

Apr 8, 2024

What do scientists hope to learn from total solar eclipse in US?

Apr 7, 2024

Huge star explosion to appear in sky in once-in-a-lifetime event

Apr 6, 2024

Three companies in the running for NASA's next moon rover

Apr 4, 2024

Let us know if there is a problem with our content

Use this form if you have come across a typo, inaccuracy or would like to send an edit request for the content on this page. For general inquiries, please use our contact form . For general feedback, use the public comments section below (please adhere to guidelines ).

Please select the most appropriate category to facilitate processing of your request

Thank you for taking time to provide your feedback to the editors.

Your feedback is important to us. However, we do not guarantee individual replies due to the high volume of messages.

E-mail the story

Your email address is used only to let the recipient know who sent the email. Neither your address nor the recipient's address will be used for any other purpose. The information you enter will appear in your e-mail message and is not retained by Phys.org in any form.

Newsletter sign up

Get weekly and/or daily updates delivered to your inbox. You can unsubscribe at any time and we'll never share your details to third parties.

More information Privacy policy

Donate and enjoy an ad-free experience

We keep our content available to everyone. Consider supporting Science X's mission by getting a premium account.

E-mail newsletter

• Share full article

Advertisement

Supported by

NASA Picks 3 Companies to Help Astronauts Drive Around the Moon

The agency’s future moon buggies will reach speeds of 9.3 miles per hour and will be capable of self-driving.

By Kenneth Chang

NASA will be renting some cool wheels to drive around the moon.

Space agency officials announced on Wednesday that they have hired three companies to come up with preliminary designs for vehicles to take NASA astronauts around the lunar south polar region in the coming years. After the astronauts return to Earth, these vehicles would be able to self-drive around as robotic explorers, similar to NASA’s rovers on Mars.

The self-driving capability would also allow the vehicle to meet the next astronaut mission at a different location.

“Where it will go, there are no roads,” Jacob Bleacher, the chief exploration scientist at NASA, said at a news conference on Wednesday. “Its mobility will fundamentally change our view of the moon.”

The companies are Intuitive Machines of Houston, which in February successfully landed a robotic spacecraft on the moon ; Lunar Outpost of Golden, Colo.; and Venturi Astrolab of Hawthorne, Calif. Only one of the three will actually build a vehicle for NASA and send it to the moon.

NASA had asked for proposals of what it called the lunar terrain vehicle, or L.T.V., that could drive at speeds up to 9.3 miles per hour, travel a dozen miles on a single charge and allow astronauts to drive around for eight hours.

The agency will work with the three companies for a year to further develop their designs. Then NASA will choose one of them for the demonstration phase.

The L.T.V. will not be ready in time for the astronauts of Artemis III, the first landing in NASA’s return-to-the-moon program , which is currently scheduled for 2026 .

The plan is for the L.T.V. to be on the lunar surface ahead of Artemis V, the third astronaut landing that is expected in 2030, said Lara Kearney, manager of the extravehicular activity and human surface mobility program at the NASA Johnson Space Center.

“If they can get there earlier, we’ll take it earlier,” Ms. Kearney said.

The L.T.V. contract will be worth up to $4.6 billion over the next 15 years — five years of development and then a decade of operations on the moon, most of it going to the winner of this competition. But Ms. Kearney said the contracts allow NASA to later finance the development of additional rovers, or allow other companies to compete in the future.

The contract follows NASA’s recent strategy of purchasing services rather than hardware.

In the past, NASA paid aerospace companies to build vehicles that it then owned and operated. That included the Saturn V rocket, the space shuttles and the lunar roving vehicles — popularly known as moon buggies — that astronauts drove on the moon during the last three Apollo missions in 1971 and 1972.

The new approach has proved successful and less expensive for the transportation of cargo and astronauts to the International Space Station. NASA now pays companies, notably Elon Musk’s SpaceX, fixed fees for those services, more akin to plane tickets or FedEx shipments.

For the company chosen to build the L.T.V., the vehicle will remain its property, and that company will be able to rent it to other customers when it is not needed by NASA.

“It’s commercially available for us as a commercial business to sell capacity on that rover,” said Steve Altemus, the chief executive of Intuitive Machines, “and do that for international partners and for other commercial companies and space agencies around the world.”

The competition created alliances between small startups and larger, more established aerospace companies, as well as car companies. The Intuitive Machines team includes Boeing, Northrop Grumman and Michelin, the tire maker. Lunar Outpost added to its team Lockheed Martin, Goodyear and General Motors, which had helped design the Apollo moon buggies.

Astrolab is working with Axiom Space of Houston, which has sent private astronauts to the space station and is building a commercial module to the International Space Station. Astrolab announced last year that it had signed an agreement to send one of its rovers to the moon on a SpaceX Starship rocket as early as 2026. That mission is independent of whether it is selected by NASA, a company spokesman said.

While Lunar Outpost is competing with Intuitive Machines on this contract, it plans to work with the company separately, sending smaller robotic rovers to the moon on the company’s lunar landers.

Kenneth Chang , a science reporter at The Times, covers NASA and the solar system, and research closer to Earth. More about Kenneth Chang

What’s Up in Space and Astronomy

Keep track of things going on in our solar system and all around the universe..

Never miss an eclipse, a meteor shower, a rocket launch or any other 2024 event  that’s out of this world with  our space and astronomy calendar .

Scientists may have discovered a major flaw in their understanding of dark energy, a mysterious cosmic force . That could be good news for the fate of the universe.

A new set of computer simulations, which take into account the effects of stars moving past our solar system, has effectively made it harder to predict Earth’s future and reconstruct its past.

Dante Lauretta, the planetary scientist who led the OSIRIS-REx mission to retrieve a handful of space dust , discusses his next final frontier.

A nova named T Coronae Borealis lit up the night about 80 years ago. Astronomers say it’s expected to put on another show  in the coming months.

Is Pluto a planet? And what is a planet, anyway? Test your knowledge here .

• Undergraduate
• Postdoctoral Programs
• Future Engineers
• Professional Education
• Open Access
• Global Experiences
• Student Activities
• Leadership Development
• Graduate Student Fellowships
• Aeronautics and Astronautics
• Biological Engineering
• Chemical Engineering
• Civil and Environmental Engineering
• Electrical Engineering and Computer Science
• Institute for Medical Engineering and Science
• Materials Science and Engineering
• Mechanical Engineering
• Nuclear Science and Engineering
• Industry Collaborations
• Engineering in Action
• In The News
• Video Features
• Newsletter: The Infinite
• Ask an Engineer
• Facts and Figures
• Diversity, Equity & Inclusion
• Staff Spotlights
• Commencement 2023

Ask An Engineer

Related Questions

• How do the blades of a jet engine start turning?
• Why can’t cars run on water instead of gasoline?
• Are Santa’s reindeer used for propulsion or navigation?
• How does an aircraft steer while taxiing on a runway?
• Can I start my car with a voice command?
• Why don’t spacecraft burn up or veer off course during reentry from space?
• Is there a way to detect my car’s keyless remote if I don’t know where it is?
• How can a person ride a motorcycle 100 mph but not stand up in a 100 mph wind?
• What’s the difference between a motor and an engine?
• Will public transportation ever replace the automobile?

What are the future propulsion systems for interplanetary travel?

In a few decades, enhanced versions of current propulsion technology could reduce travel time to Mars from about a year to a few months…

The current methods for space travel haven’t changed much in the four decades since we landed on the moon, says Paulo Lozano, H.N. Slater Assistant Professor of Aeronautics and Astronautics—though they continue to work well enough to send satellites into space, and take humans 300-400 kilometers above Earth in relative safety.

Current spaceflight depends on a rocket that burns fuel and oxidizer, which turns out to be both expensive and deficient as a means of propulsion for long-distance space travel, explains Lozano. Chemical-based rockets get terrible fuel efficiency, achieving very little thrust per kilogram of propellant used, and their exhaust velocity can’t exceed 5,000 meters per second. Using these tools, Lozano adds, it would take at least nine months to get to Mars (if your timing and the planets’ alignment are just right), and “the rockets would be huge compared to the payload.”

An alternative is on the horizon, though: the plasma rocket. “Instead of burning fuel, we ionize it, ripping electrons from atoms in the propellant,” says Lozano. The rockets use gases like xenon or krypton—the ones on the right side of the periodic table—and an electrical source accelerates the ions in the gas to create plasma. In this scheme, the higher the voltage exciting the plasma, the more velocity a rocket can achieve.

NASA has begun using a version of this kind of propulsion system for non-human space exploration, with solar arrays providing a limited but steady source of electricity for space missions that last years. But future generations of ion engines could deliver the goods for the kind of space voyages humans have long imagined, says Lozano. “There’s no impediment to applying thousands of volts to charged particles, and instead of moving five thousand meters per second, we can now have an exhaust moving at several tens of thousands meters per second, or more.” Compact and efficient nuclear reactors on board could provide the electric juice for ion engines propelling cargos swiftly from point to point in our solar system.

We’d still need the power of a chemical rocket to break the bonds of Earth, though. Ultimately, we might “take a chemical rocket taxi to low earth orbit,” says Lozano, and then “get on the high speed train, the rocket with the ion engine” to other planets.

At MIT’s Space Propulsion Lab, Lozano is working on small-scale, super-efficient thrusters for satellites. He credits the movies in part for his fascination with space travel, and specifically, with propulsion: “I saw in Star Wars that the rocket was the most important part. To escape the bad guys or explore new worlds, you needed rockets.” Personally, Lozano leans toward a combination of robotic and human discovery missions, and looks forward to a time when new propulsion systems “bring huge robotic space craft to the moons of Jupiter and Saturn, and explore these fascinating and quite exotic worlds.”

Posted: March 24, 2010

Nuclear fusion breakthrough: What does it mean for space exploration?

Some scientists say nuclear fusion propulsion is inevitable. But how far away is it, given recent breakthroughs?

The announcement this week of fusion ignition is a major scientific advancement, one that is decades in the making. More energy was produced than the laser energy used to spark the first controlled fusion triumph. 

The result: replicating the fusion that powers the sun .

On Dec. 5, a team at Lawrence Livermore National Laboratory's National Ignition Facility (NIF) achieved the milestone . As noted by Kim Budil, director of the laboratory: "Crossing this threshold is the vision that has driven 60 years of dedicated pursuit — a continual process of learning, building, expanding knowledge and capability, and then finding ways to overcome the new challenges that emerged," Budil said.

The nuclear fusion feat has broad implications, fueling hopes of clean, limitless energy. As for space exploration, one upshot from the landmark research is attaining the long-held dream of future rockets that are driven by fusion propulsion. 

But is that prospect still a pipe dream or is it now deemed reachable? If so, how much of a future are we looking at?

Related: Major breakthrough in pursuit of nuclear fusion unveiled by US scientists

Data points

The fusion breakthrough is welcomed and exciting news for physicist Fatima Ebrahimi at the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory in New Jersey. 

Get the Space.com Newsletter

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

Ebrahimi said the NIF success is extraordinary.

"Any data points obtained showing fusion energy science achievement is fantastic! Fusion energy gain of greater than one is quite an achievement," Ebrahimi said. However, engineering innovations are still requisite for NIF to be commercially viable as a fusion reactor, she added.

Ebrahimi is studying how best to propel humans at greater speeds out to Mars and beyond. The work involves a new concept for a rocket thruster, one that exploits the mechanism behind solar flares . 

The idea is to accelerate particles using "magnetic reconnection," a process found throughout the universe , including the surface of the sun. It's when magnetic field lines converge, suddenly separate, and then join together again, producing loads of energy. By using more electromagnets and more magnetic fields, Ebrahimi envisions the ability to create, in effect, a knob-turning way to fine-tune velocity.

As for the NIF victory impacting space exploration, Ebrahimi said for space applications, compact fusion concepts are still needed. "Heavy components for space applications are not favorable," she said.

Necessary precursor

Similar in thought is Paul Gilster, writer/editor of the informative Centauri Dreams website. 

"Naturally I celebrate the NIF's accomplishment of producing more energy than was initially put into the fusion experiment. It's a necessary precursor toward getting fusion into the game as a source of power," Gilster told Space.com. Building upon the notable breakthrough is going to take time, he said.

"Where we go as this evolves, and this seems to be several decades away, is toward actual fusion power plants here on Earth . But as to space exploration, we then have to consider how to reduce working fusion into something that can fit the size and weight constraints of a spacecraft," said Gilster.

There's no doubt in Gilster's mind that fusion can be managed for space exploration purposes, but he suspects that's still more than a few decades in the future. 

"This work is heartening, then, but it should not diminish our research into alternatives like beamed energy as we consider missions beyond the solar system ," said Gilster.

Exhaust speeds

Richard Dinan is the founder of Pulsar Fusion in the United Kingdom. He's also the author of the book "The Fusion Age: Modern Nuclear Fusion Reactors." 

"Fusion propulsion is a much simpler technology to apply than fusion for energy. If fusion is achievable, which at last the people are starting see it is, then both fusion energy and propulsion are inevitable," Dinan said. "One gives us the ability to power our planet indefinitely, the other the ability to leave our solar system. It's a big deal, really."

Exhaust speeds generated from a fusion plasma, Dinan said, are calculated to be roughly one-thousand times that of a Hall Effect Thruster, electric propulsion hardware that makes use of electric and magnetic fields to create and eject a plasma.

"The financial implications that go with that make fusion propulsion, in our opinion, the single most important emerging technology in the space economy," Dinan said.

Pulsar Fusion has been busy working on a direct fusion drive initiative, a steady state fusion propulsion concept that's based on a compact fusion reactor.

According to the group's website, Pulsar Fusion has proceeded to a Phase 3 task, manufacturing an initial test unit. Static tests are slated to occur next year, followed by an in-orbit demonstration of the technology in 2027.

Aspirational glow

"The net energy gain reported in the press is certainly a significant milestone," said Ralph McNutt, a physicist and chief scientist for space science at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. "As more comes out, it will be interesting to see what the turning point was that pushed this achievement past the previous unsuccessful attempts," he said.

McNutt said that getting to a commercial electric power station from this recent milestone is likely to be a tough assignment. "But the tortoise did eventually beat the hare. Tenacity is always the virtue when one is handling tough technical problems."

With respect to space exploration, it certainly does not hurt in providing an example that great things can still be accomplished, McNutt said. 

"All of that said, it should be still a sobering thought that despite all of the work on NERVA/Rover there is still no working nuclear thermal rocket engine, and the promise of nuclear electric propulsion for space travel only had a brief glimmer with SNAP-10A in April of 1965," recalled McNutt. 

The actual use of ICF in a functional spacecraft has been a long-held dream, McNutt said, but that is very unlikely to change for a long time to come.

"Space travel has always been tough. That NASA has 'blazed the trail' that many commercial entities are now following does not mean space has gotten easier, but the new ICF results have added to the aspirational glow on the horizon of the future," McNutt added. 

"That said, no one should be fooled into thinking that space will somehow not be tough someday. It's called 'rocket science,' with all that implies in popular culture for a reason," he concluded. 

Follow us on Twitter @Spacedotcom or on 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].

Leonard David is an award-winning space journalist who has been reporting on space activities for more than 50 years. Currently writing as Space.com's Space Insider Columnist among his other projects, Leonard has authored numerous books on space exploration, Mars missions and more, with his latest being "Moon Rush: The New Space Race" published in 2019 by National Geographic. He also wrote "Mars: Our Future on the Red Planet" released in 2016 by National Geographic. Leonard  has served as a correspondent for SpaceNews, Scientific American and Aerospace America for the AIAA. He was received many awards, including the first Ordway Award for Sustained Excellence in Spaceflight History in 2015 at the AAS Wernher von Braun Memorial Symposium. You can find out Leonard's latest project at his website and on Twitter.

Could these big expandable habitats help humanity settle the moon and Mars?

SpaceX launches 23 Starlink satellites in nighttime liftoff (photos, video)

Why Peter Higgs leaves a massive legacy in the field of physics

• bwana4swahili And producing 3.15MJ of output for 300+MJ is somehow a major breakthrough!? We're still a long, long, long way from anything useful!! Reply
• Vernon Brechin In order to embrace the ground-based and spaced-based fusion concepts covered in this article one likely assumes that we have 20-30 years to turn this 'Titanic' around. Such dreamers typically have become masterful at excluding the following warnings from their consciousness. IPCC report: ‘now or never’ if world is to stave off climate disaster https://www.theguardian.com/environment/2022/apr/04/ipcc-report-now-or-never-if-world-stave-off-climate-disaster UN chief: World has less than 2 years to avoid 'runaway climate change' https://thehill.com/policy/energy-environment/406291-un-chief-the-world-has-less-than-2-years-to-avoid-runaway-climate * This statement was made 4-years ago. Reply
• bwana4swahili Always gloom and doom, gloom and doom! Homo sapiens will adapt or die just as billions of species before them. Reply

bwana4swahili said: Always gloom and doom, gloom and doom! Homo sapiens will adapt or die just as billions of species before them.

• Unclear Engineer There is nothing about the climate that is going to kill off all humans by 2025, 2050 or even 2100, even if we continue to emit more CO2 than we pledged. What will happen is that a lot of our coastal infrastructures will be inundated and need to be moved or replaced, and a lot of people will find their climate has changed - some for the worse and some for the better. In the long run, if we continue as we are doing, sea level will top out at about 300' higher than today. The predictions that Earth will become unfit for life are not likely outcomes, because there will be social feedbacks that force changes in our ways. The bigger issue is whether those changes result in wars over migration that will existentially threaten our species in the nearer term. Reply

Unclear Engineer said: There is nothing about the climate that is going to kill off all humans by 2025, 2050 or even 2100, even if we continue to emit more CO2 than we pledged. What will happen is that a lot of our coastal infrastructures will be inundated and need to be moved or replaced, and a lot of people will find their climate has changed - some for the worse and some for the better. In the long run, if we continue as we are doing, sea level will top out at about 300' higher than today. The predictions that Earth will become unfit for life are not likely outcomes, because there will be social feedbacks that force changes in our ways. The bigger issue is whether those changes result in wars over migration that will existentially threaten our species in the nearer term.

• Unclear Engineer Vernon, you are drastically underestimating my credentials and experience, as well as my interest in the natural ecosystems beyond just human comfort. So, please drop the attitude that I am naïve, undereducated or otherwise unaware about the things you are advocating. I have been actually involved in the issues we are discussing for decades, so this is much more than an academic exercise for me. And, I am well aware of the IPCC and other reports on global warming - I have been following the issues since the 1970s, and am updating the projected sea levels (and local land subsidence) for impacts on my home every time there is an update, as well as following the research on the ice sheets in Greenland and Antarctica to see how new knowledge is likely to affect those estimates. I am also working on a solar installation for my property. I am also involved in habitat restorations and preservations in my local area. I don't just post about things that matter, I get out and do things that I hope will matter. So, you are going to have to adopt a more balanced style for discussing the issues if you want to have any effect on my understanding of them. Trying to come across as possessing superior education, experience or knowledge isn't getting you any traction. Debate the issues with facts, please. Reply
• Helio Vernon, ask yourself why RCP8.5 was replaced with RCP4.5? Climate modeling still doesn't have a strong grip on all the variables and how they affect climate, though it is critical that they keep improving this work. I like the use of the phrase, "climate sensitivity", to better address the real effort in climate modeling of all those variables, like the impact from CO2. Language is important and it has been abused. Consider how stupid the phrase "climate denier" sounds, which is, no doubt, intended as an ad hominem. I can't imagine anyone claiming there is no such thing as a climate? I wonder how many realize that more will die from cold than from heat in the next 12 months.? The CDC shows significantly more from cold in the US, which is based on death certificates. Other sources, however, say it is about even. Yet, world-wide, the mortality from cold is likely more than 5 to 1. here] Heat in the winter requires, currently, fossil fuels. Air conditioners made the south livable, also requiring fossil fuels. We are playing with lives of the vulnerable if we move off fossil fuels too quickly, and rhetoric suggests that's the direction being taken. Wind and solar can help but we must understand their limitations. More science, less hullabaloo. Reply

Admin said: Nuclear fusion has broad implications, fueling hopes of clean, limitless energy and the long-held dream of future rockets that are driven by nuclear propulsion. Nuclear fusion breakthrough: What does it mean for space exploration? : Read more

• Unclear Engineer Yes, that is interesting. Pulsar Fusion has made other types of engines, but not fusion based, yet. See https://pulsarfusion.com/ . Considering that their website says "NUCLEAR FUSION SET TO BE THE WORLD’S DOMINANT POWER SOURCE BY 2100", I put them in the "advocate" category rather than the "objective forecaster" category. So, when I read "Pulsar has now proceeded to phase 3, the manufacture of the initial test unit. Static tests are to begin in 2023 followed by an In Orbit Demonstration (IOD) of the technology in 2027," I am hopeful but not overly optimistic. Research groups have been building fusion devices here on Earth for decades, and none are yet "continuous" or even close to it. True, an open system is much easier to run continuously than the closed systems that the other current projects hope to create for electric power production here on Earth's surface. "Containment" becomes "direction" in open systems designed to produce thrust. But, considering how slow the progress has been on other fusion projects, I will be amazed if Pulsar Fusion gets a successful orbital demonstration as early as 5 years from now. Reply
• View All 20 Comments

Most Popular

By Harry Baker April 10, 2024

By Robert Lea April 10, 2024

By Daisy Dobrijevic April 10, 2024

By Mike Wall April 10, 2024

By Elizabeth Howell April 09, 2024

By Daisy Dobrijevic April 09, 2024

By Robert Lea April 09, 2024

By Josh Dinner April 09, 2024

By Robert Z. Pearlman April 09, 2024

By Mike Wall April 09, 2024

By Keumars Afifi-Sabet April 09, 2024

• 2 See Jupiter close to a crescent moon (Mars near Saturn, too) in the 'View a Planet Day' night sky
• 3 What happened when the moon 'turned itself inside out' billions of years ago?
• 4 Could these big expandable habitats help humanity settle the moon and Mars?
• 5 US needs new space tech or it 'will lose,' Space Force chief says