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Researchers developing fusion rocket to slash travel time of Mars missions

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April 8, 2013

Artist's concept of a fusion-drive ship

Artist's concept of a fusion-drive ship

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Traveling through deep space is a hazardous undertaking and choosing the right engine can mean the difference between a fast, successful mission and a slow one with mounting dangers of radiation sickness, equipment failures and personal conflicts. A team of researchers from the University of Washington (UW) and Redmond, Washington-based MSNW are aiming to expand the options by developing a new fusion drive rocket engine that promises to make possible a manned spacecraft that could reach Mars and return to Earth in months rather than years.

There are a number of ways of getting to Mars, but the options are pretty limited if it includes having a crew on board. The obvious choice is chemical rockets. That’s how all space vehicles from Earth are launched and most are set on their trajectories. It’s a tried and trusted technology, but long ago reached the point of diminishing returns. Without getting into the maths, using chemical rockets would mean building a huge Mars ship that is mostly fuel with a tiny payload that will take years to complete the journey.

Nuclear thermal rockets

One alternative is a nuclear thermal rocket that gets its power from splitting heavy atoms such as plutonium in more or less the same way as power plants do on Earth. These rockets have been under development since the 1940s, but none have ever been used on a space mission. There are a remarkable number of designs, from straightforward fission reactors that heat hydrogen as it passes through the core, to exotic gas core reactors.

With their greater power output and energy density, they hold the promise of more powerful engines and thus shorter journeys, but there are a lot of tradeoffs that offset the advantages – such shielding and larger tanks to accommodate lighter weight propellants. So in reality, even the most practical ones don’t reach much more than a 30 percent improvement over chemical rockets.

According to the research team, a nuclear thermal rocket Mars mission would require nine launches to put the Mars ship into Earth orbit at a cost of more than US$12 billion – and that doesn't include the rest of the budget for building the ship, exploring Mars or making the tea. The ship would weigh 848 tonnes (935 tons) and a round trip mission to Mars would take 4.6 years.

“Using existing rocket fuels, it’s nearly impossible for humans to explore much beyond Earth,” said lead researcher John Slough, a UW research associate professor of aeronautics and astronautics. “We are hoping to give us a much more powerful source of energy in space that could eventually lead to making interplanetary travel commonplace.”

Fusion Driven Rocket could be the answer

The team believes that they can do better using a Fusion Driven Rocket (FDR). As the name implies, it uses fusion, the fusing of light elements, as a power source instead of fission. There are a number of ways of causing fusion and here the Washington team is using a Field Reversed Configuration (FRC).

FRC fusion engine

A FRC is a device for confining plasma on closed magnetic field lines without a central penetration. It uses huge electric capacitors powering an extremely powerful magnetic field with one million amps that causes large lithium metal foil rings to implode on a blob of ionized hydrogen plasma as it squirts into the engine. The metal foil squeezes the plasma for a few microseconds until fusion occurs. The magnetic field then channels the superheated, ionized metal out of the rocket nozzle at high velocity in a pulse of thrust.

It’s not a very smooth ride. The pulses come at one minute intervals, so the ship travels in a series of jolts rather than a constant thrust, but the Washington team believes that it can do the job and is very efficient with only a bit of material the size of a grain of sand producing as much power as a gallon (3.7 l) of chemical rocket fuel. According to the team, a Mars ship using the FDR engine would have a mass of only 134 tonnes (148 tons), need only one launch to put it into orbit, and could make the trip to Mars and back in 210 days with a 30 day stopover.

Details of a fusion-drive ship

Currently, the team is working to develop individual components and then combining them into a working prototype of a whole engine. “I think everybody was pleased to see confirmation of the principal mechanism that we’re using to compress the plasma,” Slough said. “We hope we can interest the world with the fact that fusion isn't always 40 years away and doesn't always cost $2 billion.”

The results of the team’s work was presented last month at the 2013 NIAC Symposium.

The brief animation below shows how the fusion drive works.

Sources: University of Washington, MSNW

About the Author
David Szondy David Szondy is a freelance writer based in Monroe, Washington. An award-winning playwright, he has contributed to Charged and iQ magazine and is the author of the website Tales of Future Past.   All articles by David Szondy
22 Comments

1 million amps?

blobs of ionised hydrogen plasma?

Where do these come from?

Adrien
9th April, 2013 @ 03:06 am PDT

Not a convincing argument that fusion is required for a manned Mars trip.

Also, not a convincing fusion rocket engine design, and it appears to require a small nuclear fission reactor to supply the electricity to run it. But at least the company has built actual hardware and this is not entirely a computer graphics fantasy.

MBadgero
9th April, 2013 @ 05:39 am PDT

Sounds like a higher-tech version of the Orion nuclear pulse rocket design from the late 1950's - 60's that Freeman Dyson worked on.

Dave MacLachlan
9th April, 2013 @ 07:52 am PDT

still need HLLVs to boost atomic rocket into Orbit for assembly alone.

& need to expand ISS for role or add other Orbital Hub

Be radical to get to Mars in months vs years, radical.

Stephen N Russell
9th April, 2013 @ 09:06 am PDT

I doubt that the solar panels in the illustration would provide enough power to make this work.

for deep space operations you need to have a high yield radiation shield to protect against solar flares putting a fission reactor on the sunward side of the shield is not a problem.

Slowburn
9th April, 2013 @ 09:44 am PDT

I worked on a project at Lockheed Sunnyvale in the early 60's called RIFT Reactor In Flight Test nuch different that this, Very Interestion

Dick Doeren
9th April, 2013 @ 09:48 am PDT

Whether this machine proves viable or not, it or others like it will make our solar system seem much smaller and more reachable. I agree with MBadgero. This technology is not essential to make it to Mars. We already have technology that can do that, but research like this is good and the potential of cutting travel time in half or better is nothing to dismiss lightly. I hope they make enough progress to keep the funding going so that they can make a practical machine. It seems like a solid concept. We have a hard time keeping fusion reactions contained in our stationary fusion reactor labs but we don't need to contain them with a fusion propulsion engine. What was a problem becomes something wonderful: THRUST!!

Rustin Haase
9th April, 2013 @ 10:03 am PDT

Mars Mars mars, blah blah blah.

The resources we need are on the Moon, not Mars. Everyone is in some sort of hurry, and wants to skip the logical step.

That error will cost us dearly.

Bob Komarek
9th April, 2013 @ 11:55 am PDT

#Dick Doeren - Did you mean "not much different"?

Looks like you're no longer with Lockheed; can you tell us more about the old program? I don't remember it, myself.

David Bell
9th April, 2013 @ 12:08 pm PDT

Ion engines work now??? just use a nuke power source!

Leonard Foster Jr
9th April, 2013 @ 06:22 pm PDT

Oh, By the way, the output hydrogen gas is DEFINITELY radioactive... details, details... They are testing it on Earth now - no mention of containment... May be when the ISS will look down, it will see the blue-white glowing of the test facitility and can track the people who work there and live nearby that way too? I want (and NEED) a high-output "star-drive" too, but perhaps we should look at consequences also at the same time?

Just a thought...

AsteroidMiningGuy
9th April, 2013 @ 08:38 pm PDT

When I first saw the description I was very skeptical because fusion has not passed break-even energy performance were the energy created by the fusion reaction is greater than the energy to start the fusion reaction.

On reflection I realized that break-even is not required. At close to break-even the energy heating the propellent would be double the external energy input thus greatly increasing the potential specific thrust. Also the temperatures achieved could greatly exceed those of chemical reactions and ion drives so the performance potential is greater.

It is disappointing that no information about energy requirements for the fusion drive was given.

Dominic From NASA
9th April, 2013 @ 09:04 pm PDT

This is not offering shorter duration trips than ion rockets.

Slowburn
9th April, 2013 @ 09:35 pm PDT

re; AsteroidMiningGuy

I don't see hydrogen 1&2 picking up the neutrons to become hydrogen 3. The helium produced by the fusion probably will be radio active but is a very low percentage of the exhaust.

Why is this a problem?

Slowburn
9th April, 2013 @ 11:33 pm PDT

Slowburn, the helium is not radioactive, but the neutrons produced are, and they can cause other materials to become radioactive.

If you dig through the links from this article you will find a paper by John Slough and David Kirtley, "Nuclear Propulsion based on Inductively Driven Liner Compression of Fusion Plasmoids". This shows the authors knowledge of plasma physics, and while the paper spends a lot of time on fusion reaction basics it also explains their engine design, which is plausible. However, it unfortunately also shows their lack of knowledge of Mars and currently planned Mars missions.

MBadgero
10th April, 2013 @ 05:25 am PDT

Very cool idea. i like that it does not require the fusion reaction to get more energy out then put in. all it requires is large amounts of thrust to be created. sounds like it could work. But where is this huge amount of power gonna come from to power this magnet? certainly not those puny solar panels... for now it seems like space flights only hope is compact fission reactors such as the ones used on naval submarines and aircraft carriers currently.

brahmo
10th April, 2013 @ 06:27 am PDT

shades of "to the moon and back" from 50 years or so back using dynamite to produce quick bursts.

so i am wondering what the g force of each fusion event will be on the passengers?

notarichman
10th April, 2013 @ 12:25 pm PDT

re; MBadgero

There are eight known isotopes of helium, but only helium-3 and helium-4 are stable. I went with my experience playing dice.

re; notarichman

Use springs and dampeners. Although optimally would be to time the thrust pulses to the springs natural oscillation.

Slowburn
10th April, 2013 @ 02:48 pm PDT

NASA should stick with the stolen UFO technology at area 51

Stewart Mitchell
10th April, 2013 @ 04:27 pm PDT

Please correct me, but in order to reach the speed to go to mars and back with this only bursting 1 time every minute, wouldnt the amount of G force created on each burst roughly force the ship forward at 1000mph instantly? the g's would destroy the ship and all the people on board.

Ranscapture
11th April, 2013 @ 12:04 am PDT

re; Ranscapture

The transit time they are suggesting are about the same as for ion rockets that run for the duration of the trip. Assuming one hundredth of a G acceleration for the ion rocket ship makes each pulse add 6.144 feet per second (4.189mph) to your velocity. 0 to 60 in 6 seconds adds 10 mph per second So with a good spring between the thruster and the rest of the ship the acceleration is quite comfortable.

Slowburn
11th April, 2013 @ 10:34 am PDT

Yeah, I think if they can find a power source that produces 1 million amps every minute and be able to create a magnetic field that can squeeze that fusion explosion out a nozzle, they can power the rocket with it. Forget about the fusion.

Ellison Chan
10th November, 2013 @ 10:50 am PST
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