Feature
Veteran astronaut Franklin Chang Diaz has spent four decades developing his rocket fueled by nuclear reactors and liquid hydrogen. Now NASA just might let it fly

Artistic Rendering of the Vasimr Engine: The Vasimr rocket uses an enduring electrical source, such as a nuclear reactor or a solar generator, to transform hydrogen gas into plasma. Powerful magnets force the plasma out of the engine to propel the rocket at 123,000 mph.  Daniel Schumpert/Jason Briney

The Challenge
Chang Díaz, of all people, knows how hard it is to return safely to Earth. His career was bookended by death—death that could have been his own but for the routine tweaks of NASA’s scheduling log. The agency decided to pull him off his first scheduled mission on the space shuttle Challenger in 1986 and put him on the mission just before instead. Sixteen days later, newly returned to Earth, he watched his close friends and colleagues perish when Challenger exploded 73 seconds after takeoff. He went on to fly a total of seven missions between 1986 and 2002—he’s tied for the all-time record among astronauts—and logged 1,601 hours beyond Earth’s atmosphere. Then, a few months after his final mission, Columbia broke apart during reentry, killing all seven people aboard.

Chang Díaz’s invention will do little to reduce the dangers of liftoff. Plasma engines depend on the vacuum of space and still require “venerable chemical rockets,” as Chang Díaz calls them, to reach Earth orbit. But outer space is where his work stands to vastly improve the safety of a crew. As he points out, a lot can go wrong en route to another planet. The limitation of space travel with a conventional rocket is that the rocket must use its entire fuel supply at once in a single, controlled explosion to reach Earth orbit. It then coasts along at a mostly uniform speed until it enters Mars’s gravity. NASA estimates that such a trip would take about seven months. During that time, Chang Díaz explains, there is no abort procedure. The ship cannot change course. If an accident occurs, Earth would be watching, in a 10-minute communications delay, the slow death of the crew. “Chemical rockets are not going to get us to Mars,” he says flatly. “It’s just too long a trip.”

A plasma rocket like Vasimr, on the other hand, sustains propulsion over the entire journey. It accelerates gradually, reaching a maximum speed of 34 miles per second over 23 days. That’s at least four times as fast as any chemical rocket could travel, shaving at least six months off a trip to Mars and minimize the risk of mechanical dangers, exposure to solar radiation (Chang Díaz’s design shields the crew behind hydrogen
tanks), bone loss, muscle atrophy or any of a thousand other liabilities along the way. And because propulsion is available throughout the trip, the ship could change course at any time.

But human spaceflight programs are currently built around old-fashioned rocketry. NASA has invested mostly in propulsion systems powered by chemical fuel, and for sensible reasons. Chang Díaz’s rocket presents many challenges. For one thing, a Vasimr-powered Mars craft would need several nuclear reactors on board to generate the large amount of electricity required to heat the plasma. NASA set to work on a nuclear reactor for space travel in 2003 but scrapped the project after only two years—the risk of radiation from an explosion or crash was likely too great— and redirected its resources to more conventional propulsion programs. For another, no one has yet determined how to make certain that plasma gas can be safely channeled through a magnetic field. Or just how the human body might respond to traveling at speeds of up to 34 miles per second. “The reality is, rockets don’t always work,” says Elon Musk, the driving force behind the rocket company SpaceX, one of the key players in the emerging private space industry. For Musk, who struggled for years to get his Falcon 1 rocket into orbit, the stakes seem particularly high in the case of rockets carrying nuclear material. “If something goes wrong, you have radioactive debris falling to Earth—you have a disaster,” he says.

It’s true that conventional rockets would be required to put a Mars-bound plasma ship into orbit, but Chang Díaz disputes the notion that launching Vasimr would pose extra risks. The reactors would remain inactivate until the ship was out of the danger zone for spreading radiation back to Earth, he notes. And NASA has already successfully launched several nuclear-electric probes. Nothing is impossible. “We can do this safely,” he says. “Our understanding is evolving all the time, but we know that in order to go far, we have to go fast. That’s what Vasimr is all about.”

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36 Comments

You can do it, buddy! Where do I sign up?

"NASA set to work on a nuclear reactor for space travel in 2003 but scrapped the project after only two years—the risk of radiation from an explosion or crash was likely too great"

You guessed wrong. Launching nuclear reactors into space presents significant challenges, but they are not insurmountable. For example, Mars Science Laboratory is set to launch next year with 10 pounds of plutonium on board. NASA's work on nuclear propulsion begun in 2003 was scrapped two years later because the money was reallocated to the Constellation program. Many other promising science and technology programs suffered the same fate.

We Gotta keep Strivin' Foward ..Pushin' ahead..Someone has got to Lead The way ...Continue to Keep Pushin Positively Forever Forward into the Future..

The best possible future ..Would be to.. Explore/Inhabit other Worlds/Planets..And Still have a home to come back to for Supper...

Over and Out there from Here ...DEEEEEP SPAAAACE...( Spend half my time there ;))

;):)

is it possible to use anti-matter to heat the plasma?

I'm seeing star treck in the near future (minus the WWIII part)

Such a propulsion system is so vital to our future exploration of space(both robotic and human), I'm surprised it hasn't caused much more of a stir than it has so far. The obvious advantage to the decrease in data recovery wait time is such a strong advocate all by itself, especially for more distant gas giants & dwarf planets. I hope the wait won't be too much longer.

You guys should of put that 10 min interview vid. on N. Science Now of the plasma engine in action.

You'd probably have to buy the rights to do so though.

Would a space elevator be a possible solution to the nuclear element? If people are worried about putting something explosive near a nuclear device, why not have the nuclear device assembled, shipped up to space, then attached to the ship after it leaves the atmosphere? This may seem a little sci-fi, but bear with me. Not only would you need less fuel to lift the spacecraft into space, there would be no risk of nuclear explosion in the atmosphere. To me, it seems like a viable option (assuming we ever build a space elevator, that is XD).

I don't get the bit where the article says we don't know "just how the human body might respond to traveling at speeds of up to 34 miles per second."

... um, my understanding of this is that the astronaut won't be able to tell what speed he is going. So I'm guessing the response will be boredom.

Yeah. That was a little weird. It's not like 34mps is a relativistic velocity. Acceleration, though constant, is almost zero. Whats the problem?

Sounds like historic naysayers to space travel, breaking the sound barrier, human flight, running the one minute mile etc.

We, all Costa rican people are very proud about Franklin Chang Díaz achievements. We all know his goals for an interplanetary engine will prove realistic in the future.
Go on Franklin.

Jose L. Castro, EE, Costa Rica

I read somewhere that you can use shuttles to bring up parts and assemble it in orbit, rather than launching it from Earth or using a space elevator. Maybe that's an idea.

Do people bother to read articles?

This article doesn't propose anything to do with a space elevator. So why ask?

Nor does the article say anything about how a Mars mission craft would be assembled, in orbit or otherwise. However, common sense does suggest that a Mars mission ship will be a tad large, I'll make a guess and say that it will need to be several hundred tonnes. No rocket exists that could launch this from Earth, and ... um, we don't seem to have a space elevator handy, so maybe, just maybe, they might be considering building it in orbit.

... maybe I should post my reply 38 times, so that the idiots will read it.

Great article...

This article is worthless. "That's how you grow," this article claims, and that by destroying the government and NASA?
I am just wondering which private corporation was instrumental in sending the first astronauts to outer space and then to the moon in the 1960s. Was it Enron or perhaps Virgin Galactic or SpaceX?

If the morons will think, then of course we need NASA and government funding to get us to mars and then to build these space vehicles and the infrastructure to get there. This will never work and who is so dumb to believe this article that destroying NASA and government is what we need to get to space. As it is already doing it is killing space travel.

SCIENCE FICTION IS NEAT

The G-force effect on the human body isnt even a factor through 'gradual accelleration'.

As it is, we on earth are already traveling at just over 1000 miles per hour.
When lauched into space at almost 29,000 mph and the G-force, though brutal, is still something we have no problem with.
Like anything in travel...the force on the object (human or craft) is noted in the cause of the friction and the friction itself.
One of the main causes of friction or negative force is gravity and atmosphere...
In space there is no such atmosphere and gravitational pull is at a pretty large minimum unless you aproach another object of substantial mass.
Thus, at a gradual increase in speed, much like one does with an accellerator in a car a body would eventually reach a level of comfort at speeds at 173,000 mph in an environment that has little or no resistance to the human body itself.
The world may be passing by at extremely accellerated speeds, but in our 'lil' world, everything is seems normal.

The only thing I have a problem with is how this guy plans on making a reactive plasma engine that can sustain temperatures of 2 million degrees for long periods of time without melting the engine itself.

The highest melting point of any element or carbon alloy, doesnt even come close to sustaining these temperatures.

Currently the record-holder is tantalum hafnium carbide (Ta4HfC5), a refractory compound with a melting point of 4488 K (4215 °C, 7619 °F).

Rocket boosters only reach a maximum temperature of 6000 degrees F.

So I would say hes got a long way to go, just to build an apparatus that can hold his Idea.

You think space travel is dangerous and tedious now? Try sending something that needs to heat up to 2,000,000 degrees F out of our atmosphere. It would just melt or probably go 'poof!' in about two seconds.

Great Idea...but unless this guy has God himself holding the reactor...its not going to happen.

I mean for crud's sake the surface of the sun is waaaay colder than what he is saying hes going to accomplish with heat exhaust prepulsion.

Check what I found on Ad Astra's website!

http://www.adastrarocket.com/aarc/VX200

Look at the fifth picture with the caption "A photograph of Ad Astra scientists using a laser alignment rig with the VX-200. Credit: Ad Astra Rocket Company"

Is that a NORTH KOREAN flag on the laser alignment rig?

With gradual accelleration, the speed is not an issue. What IS an issue is going to be micro-meteorites or other floating spatial material that will strike the surface of the spacecraft moving that fast, and will more than likely penetrate the ships' outer hull. The second big concern will be how effectively the craft can rotate so as to not have its sides exposed to cosmic radiation for any given length of time as it will eventually be a health concern of radiation exposure. Now, given the velocity they are trying to achieve, I would think the stress caused in trying to moderately turn a craft on an axis would be quite significant.

@ dontbother

it looks like it but why would it be there.

The picture isnt high quality enough to get a match

@dontbother

The flag is from Costa Rica.
Your first clue should have been from a previous comment from jlcastroa that began "We, all Costa rican people are very proud about Franklin Chang Díaz achievements."

I still think the most viable solution to Mars in 39... Is to use a nonconventional nuclear reactor... A liquid thorium.... Much safer, much lighter, well within today's technology ... To power this plasma drive our friend above is taking about. And thorium is both plentiful and makes a good solar radiation shield.

best way of getting the nuclear material into orbit without harming anyone or burning too much fuel, would be to package it into an unmanned rocket which would be piggy-backed on a plane, flown up to near atmosphere, launched in mid air. this way, any risk should be massively reduced. if its unmanned, we dont lose our genius astronauts. only downside, is that as we all know, a nuclear explosion in the upper atmospher would cause an e.m.p. as for the heat issues, there would be minimal friction due to the use of magnets, and the speed at which you would be travelling would keep you away from the heat, because the plasma that is being heated is being ejected and left behind you, plus the fact that by the looks of the design, the hydrogen is whats being burned, and that being used as a catalyst for the plasma as it is ejected, not within a chamber or otherwise. before he lost his arm, my dad was an aircraft engineer, im not, but learned a few bobs. seems like a sweet design to me. and lets face it, if nasa has let the dude into the fold, he clearly has some kudos, else they'd have just told him they held a patent themselves and kicked him to the kerb.

@jaydeadone It doesn't seem that you read the whole article.

Of course there's no material which can contain anything at such temperatures, however in the article and drawings you can see that the idea is to hold the plasma with magnetic fields.

And this is not just an idea, it's something that they are already doing in their labs, that's why their plans have realy near dates (in this industry two years is a really short term).

Just to set you guys straight. It is not a nuclear explosion or reactor melt-down they are worried about. That should be easy enough to avoid. What they are referring to is the chemical rocket taking the reactor to orbit exploding and dispersing the nuclear material in the atmosphere causing radioactive fallout. Think dirty bomb, not A-bom/H-bomb.

As for the 2 million degree plasma burning up the containment vessel. I would hazard a guess that electro-magnetic fields would be involved in containing it rather than physical walls.

Another proud Costa Rican citizen salutes you Franklin; live long and prosper!

I hope to see you flying in your own spaceship and hopefully to Mars!

Thanks for being a AAA citizen!

I find it incredible that we Earthlings don't give a hang about releasing nuclear radiation IN SPACE. All the comments I read seemed to say "As long as we can get the nuclear propulsion hardware safely into space, then there's no reason not to use it.
Is the assumption that extraterrestrials are so likely to be of a totally different biology, that we don't even have to consider their safety, in indiscriminately spewing some serious half-life matter in all directions. And please, no lectures on the vastness of space. Our vehicle is presumably going SOMEWHERE, and how will that somewhere not become contaminated? I'll try not to mention the potential danger to the crew. I respect their bravery and scientific curiosity. The astronaut/inventor, Mr. Chiang Diaz himself, states he plans to use this technology as propulsion for his start up space garbage trucking company. And though he's operating in a vacuum literally, such work will no doubt entail contact with other spacefarers, so in that sense he won't be irradiating 'in a vaccum.'

OK, I think I understand that the fission is expected to be contained, and only the plasma, when superheated by the fission, will be expelled into space. Can this be done without the plasma becoming radioactive? And what is the percentage likelihood of this new technology working perfectly from the start, and successfully containing all nuclear radiation?
Oh I forgot, that's a risk that can be safely ignored.
?

Viva Costa Rica just the same. I had a great friend from there, turned me on to Elvis Presley in 1957 : )

tommym, I believe there is quite a bit of radiation in space already. We do happen to have a totally unshielded fusion reactor hovering somewhere near the center of our solar system.;) Also, it is believed that we have a super-massive black hole at the center of our galaxy, which most likely is spewing out x-rays and other forms of radiation.

The concern about accidentally spreading radioactive material around the globe, should a space launch go wrong, is valid and unfortunately has happened before. However, I'm sure that hasn't stopped NASA or the US military or the Soviet Union from launching significant amounts of nuclear material into orbit. While I'm sure it's not exactly routine, I'll bet we know how to push a few pounds of nuclear material into space with a reasonable degree of safety.

Congratulations to Franklin Chang Diaz and good luck with this exciting project.

@tommym "But what about the safety of the aliens?" Did you seriously just turn all environmentalist about aliens that we're not even sure exist? That's gotta be a first, not to mention the looniest species-protection argument ever made. If there are even any aliens where we're going at all (and there's obviously no guarantee of that), it's not like we're talking about dropping nukes on another planet here. Nor would the propulsion system be pointed directly at the planet, anyway - it'd be facing the other way.

As for the risks involved, why do you the guy is proposing to gradually test the engine type on a smaller scale first? It's not like he's suggesting that he wants to just build the full-scale Mars exploration rocket right off the bat. There are always risks involved with every new technology, but scientists with brains, like Diaz, don't let that stop them. They just keep improving their inventions until the risk is minimized to an acceptable level. I, for one, hope he gets his design to that point soon, because all of mankind could stand to benefit as a result. Go for it, Diaz!

a nuclear explosion going off in the upper atmosphere would be one of the worst things that could happen to the planet

sometimes it pays to go towards the direction of science fiction. otherwise you either take tiny incremental steps that get you nowhere in a hurry or you get the budgetary ax or political ax.

to the person who asked about antimatter it is just on the edge of possibility and if you could get enough of it and store it safely it will heat the exhaust gas far more powerfully. in fact it is the only known way to get significant payload to relativistic speeds necessary for interstellar travel. fusion won't do it nor will nuclear fission augmented gas or plasma rockets. and light sails or beamed propulsion isn't exactly feasible either for a number of reasons. at least not for interstellar travel. maybe inside the solar system.

the first problem; where to get it or make it is yielding to progress now. initially the PAMELA probe confirmed only small amounts in the upper atmosphere. however the measurements have subsequently been greatly upgraded. and that does not count particles of it around other planets with atmospheres or near the sun. also progress has been made on technology to generate it on earth.

the second problem essentially how to keep it from accidentally blowing up; may be solved by forming it into neutral anti-hydrogen and then freezing it into a solid or slush and then using dimagnetism to suspend it in vacuum chambers. this renders it much safer (relatively speaking) than traditional magnetic schemes and does away with erosion of the vessel walls by straying particles. Magnetic traps always leak if they are used to contain gas or plasma. with antimatter ice in a vacuum there are far fewer stray particles.

these vacuum chambers should be small with fail safes for the dimagnetic suspension, vacuum pumps, and cryogenics systems and be ejectable in the event of imminent failure of those systems. each chamber should have independent containment cooling and vacuum systems so that failure of one chamber does not result in an annihilation reaction of all the stored antimatter in all the others. a pusher plate and separation collar should be between the fuel area and the rest of the ship so that a catastrophic failure of containment hopefully pushes the crew section away from the blast in the event of containment failure.

and to the guy worried about irradiating aliens...

well lets just talk abotu the technical reasons why that isn't a problem for either Chang's invention or for that matter most of the other schemes using nuclear reactors indirectly like VASIMR and closed system fission nuclear rockets.

the radiation is in the reactor and the propellent travels through the reactor to pick up heat. the radioactive stuff is not mixed with the exhaust. radioactive stuff could only be released if the rocket blew up or broke apart. VASIMR uses the power generated by the reactor to power the VASIMR magnets and plasma heating.

now it is true that more advanced nuclear concepts which produce higher specific impulse and delta V's do mix the propellant with the nuclear stuff and they should never be considered as a means to get something off the earth's surface.

ok, now as to your objections to irradiating aliens you are aware that all the elements we have (except a tiny bit we make ourselves) beyond helium come from stellar explosions. this includes BTW uranium and plutonium so there are billions and billions or trillions of massive radioactive engines of alien destruction and genocide going on all the time. poor aliens.

a nuclear explosion in the vein of nuclear bomb like explosions are impossible in a reactor. thats called a super critical reaction and it takes a lot of special effort to generate that. firstly the nuclear material must be enriched to bomb grade which is significantly higher than the grade used in reactors. secondly to get enough neutrons hitting nuclei the fissile material must be machined to the perfect spherical shape. then there must be enough fissile material in the sphere of material to maintain the reaction long enough to get explosive amounts of matter energy conversion. in the case of fusion bombs there must be a properly shaped special explosive packed around the plutonium pit. these must be detonated in precisely the correct timed sequence to start an even inward compression of the nuclear pit. without tritium doping the amount of plutonium must be much larger than what would be required for a modern weapon and presumably for the little rods or balls of stuff used in a reactor.

none of these conditions exist in a reactor and therefor a reactor going wrong on the way to space cannot blow up like a nuclear bomb. so no EMP. what could happen is the nuclear material could be dispersed in the atmosphere and present a mutation and cancer hazard for people in the fallout zone. but it is not a planet killer. when nuclear bombs were being tested several atmospheric and open ground and oceanic explosions occurred. Though i would not recommend exploding bombs like that we are still around, the world is not lifeless and we don't have eyeballs in the center of our foreheads.



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