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New ion engine could reach Mars in 39 days


July 28, 2009

The VASIMR engine could make a manned flight to Mars in about a sixth of the time of conventional rockets

The VASIMR engine could make a manned flight to Mars in about a sixth of the time of conventional rockets

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Last week, as the world celebrated the first lunar landing, Apollo 11 astronauts Buzz Aldrin and Michael Collins both called for NASA to make Mars its next goal. But the chemical propulsion system that took them to the moon would take six months, at least, to get a man to Mars and cost hundreds of billions of dollars. However, a new ion plasma rocket being developed by another former astronaut, Franklin Chang-Diaz, could potentially reach Mars in just 39 days using a fraction of the fuel.

The problem with traditional rockets is that they’re terribly inefficient. About 90% of a mission’s initial weight is fuel, most of which is burned up escaping earth’s gravitational pull. After that, a traditional rocket could only slowly coast to Mars. Very slowly. Scientists describe rocket efficiency in terms of specific impulse, which is a rough measure of how fast fuel is ejected out of the back of the rocket. A chemical rocket has a relatively low specific impulse of 450 seconds - in other words, it gets one pound of thrust from one pound of fuel for 450 seconds.

Chang-Diaz’s prototype, however, promises specific impulses as high as 15,000 seconds. How? Well, his rocket doesn’t achieve propulsion by combusting fuel but, rather, by superheating atoms to create and expel a plasma plume.

The Variable Specific Impulse Magnetoplasma Rocket (VASIMR, for short) consists of three linked magnetic cells. The first stage works a bit like a kettle, heating the atoms of a neutral gas like argon with a radio frequency (RF) generator until electrons “boil” off, creating plasma.

The plasma is now very hot – about 50,000 degrees Celsius – but not hot enough to produce efficient thrust. The second stage of VASIMR acts as an amplifier, further energizing the plasma using electromagnetic waves. By now, the plasma reaches about a million degrees, comparable to the center of the sun.

The third and final stage is a “magnetic nozzle” that converts the energy of this superheated plasma into directed motion and, ultimately, high velocity thrust. And, in case you’re wondering how anything so hot could be possibly contained, that’s one of the reasons the cells are all magnetic. A magnetic field not only helps heat plasma but also contains it, so it won’t ever actually touch anything.

VASIMR could, theoretically, reach power levels a hundred times that of other ion engines. But there are still two big problems that need to be addressed before anyone can start packing their bags for Mars.

The first is that the 200kW VASIMR only produces a pound of thrust. That’s more than enough in the vacuum of space, where the ion engine can fire continuously for months on end and a pound of thrust can push two tonnes of cargo from the sun to Jupiter in 19 months. But it means VASIMR will never get off the earth on its own – it would need to catch a lift with one of those old gas-guzzling rockets.

The second issue is that, while the current engine can run entirely on solar power – making it perfect for moon trips and other near-earth duties – for a deep space mission, it would need more like 200MW of power. And only an on-board nuclear reactor could provide that.

In the meantime, Chang-Diaz and his colleagues at the Ad Astra Rocket Company (such a wonderfully old-fashioned name) are busy readying VASIMR for a 2012 test with NASA on the International Space Station. It could just be the beginning of a new power in long-distance space travel.


this is cool

Jimi Joe

39 days... Do I need to say more?

Robert Gray

About time!!!

Chris Doble

only if we get a pretty ion blue thrust flame. none of this insane ultraviolet radiation thrust look, get Mr Lucas to fine tune it for looks :) actually no, it'll end up with a Jamaican accent... never mind testing it at the ISS. ATTACH one and get in some cruising.

Craig Jennings

no words in world for that stuff. so we r reaching closer to light's speed....................

Facebook User

What about an orbital based spacecraft?. A vasmir spacecraft could be kept in orbit attached to the iss and launched from there. there has been a break through in magnetic fields to protect astronauts from solar flares and radiation so lets stop talking about it and get out there!!

David Kelly

may be is posible to launch vessels with suplies from an hercules like plane flying near the space to reduce chemical fuel, this kind of launching has been announced but never built, does anybody know why?

Juan Elgueta

And that 39 days is with the 200kW solar powered version.... just think how much would be cut out of that if it were the 200MW version. only a few days to get to Mars!

@Craig Jennings, The current ion drive does have a blue plume, but it is actually kinda hard to see. Since this one is much more powerful, maybe we will get a nice bright exhaust!

Jay Lloyd

Why not combine it with the Startram maglev train? Synergy!


First off; can we please get an update on this project? It's 2012 let's see where they are at.

Second; someone should tell these guys: http://www.gizmag.com/mars-one-human-settlement-2023/22799/ about this.

Third: "...only produces a pound of thrust..."? so strap 1000 of these suckers on the back of a ship and see how fast it goes.


How about LENR as the power source?

"A volume about the size of a #2 pencil eraser of water provides as much energy as two 48-gallon drums of gasoline. That is 355,000 times the amount of energy per volume – five orders of magnitude." ( http://oilprice.com/Energy/Energy-General/New-LENR-Machine-is-the-Best-Yet.html ).

This phenomenon (LENR) has been confirmed in hundreds of published scientific papers: http://lenr-canr.org/acrobat/RothwellJtallyofcol.pdf

"Over 2 decades with over 100 experiments worldwide indicate LENR is real, much greater than chemical..." --Dennis M. Bushnell, Chief Scientist, NASA Langley Research Center

"Total replacement of fossil fuels for everything but synthetic organic chemistry." --Dr. Joseph M. Zawodny, NASA

By the way, here is a survey of some of the companies that are bringing LENR to commercialization: http://www.cleantechblog.com/2011/08/the-new-breed-of-energy-catalyzers-ready-for-commercialization.html

For those who still aren't convinced, here is a paper I wrote that contains some pretty convincing evidence: http://coldfusionnow.org/the-evidence-for-lenr/

Brad Arnold

"...it would need more like 200MW of power. And only an on-board nuclear reactor could provide that."

So? Why this continuous disparagment of nuclear power?


The real cost of space flight is not the fuel its the rocket. We build a $70,000,000 rocket and throw it away after one launch. The fuel only costs $200,000. About 0.3% of the cost of a launch is the fuel. Once we get 100% reusable rockets space flight will only be expensive not prohibitive. SpaceX is well on the way to having truly reusable rockets. There grasshopper test system has demonstrated rocket powered take off and landing to close to a mile altitude. They are moving testing to a new site where they can go higher. They hope to be to 60 mile altitude by next year. It does not take much fuel to land an empty booster.


I know I'm showing my ignorance but; won't it spend half the time in reverse to slow back down. I never see that mentioned in terms of interplanetary trips. Thkx

LeeLoo Dogert

I got a question: would this engine also provide a better fuel volume to thrust ratio compared to a jet engine wich runs on kerosene

Dave GearHead
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