Fusion power has long been the dream of those seeking endless energy supplies, although efforts to smash atomic particles together and harness their energy have been dubious at best. Now a NASA scientist is proposing a new form of fusion-based energy to power a deep space probe.
Instead of using fusion's excess energy to drive a generator, it would use the kinetic energy of radioactive decay particles to provide thrust.
John J. Chapman, a physicist and electronics engineer at NASA's Langley Research Center, proposes a boron-based fusion motor instead of a system based on deuterium and tritium. He explained the system at an IEEE Symposium on Fusion Engineering in Chicago this week.
It uses a commercially available laser beam aimed at a two-layer, 8-inch diameter target, IEEE Spectrum explains. As the laser beam hits the first layer, am ultra-thin piece of metal foil, it releases a hail of electrons, leaving the foil with a net positive charge. The protons' self-repulsive force causes the foil to explode apart, propelling protons toward the second layer, a thin film of boron-11. Here the protons fuse with boron nuclei to form carbon nuclei, which immediately decay into daughter products, which themselves decay into alpha particles.
IEEE Spectrum explains: "For each proton-boron pair that reacts, you get three alpha particles, each with a kinetic energy of 2.9 megaelectron volts."
The electromagnetic force pushes the alpha particles in opposite directions, and they are directed to exit the spacecraft through a nozzle, providing thrust.
A laser is needed to jump-start this process, but each pulse from a beam producing 2x10-18 watts per square centimeter should generate 100,000 particles, Chapman says, so it's highly efficient. Just 11 grams of boron would yield 300 MW of power, Chapman tells IEEE. He even believes some of the energy can be used to power a spacecraft's computer systems.
This is a long way from reality, of course — Chapman says it could take a decade of work to build a functional spacecraft powered by this method.
Boron is abundant on the Earth, and if a few grams of the stuff can drive a spaceship to Mars and beyond, it's an idea worth studying, at the very least.
Could you test this idea now with an alpha decay source?
11 grams can produce 300MW of power? Why worry about Spacecraft when this would solve the energy crisis?
Love it, I'm very glad there are scientists thinking about ways to get us to do space travel faster. I wasn't aware you could release so much energy this way-sounds like it'll be good for use on the planet (for power plants and vehicles) as well as for space travel.
Of course we'll need some technology to get us close to the speed of light for voyages to other stars, but this is definitely a step in the right direction.
While it may not get us interstellar travel right away, maybe it's fast enough to get let us vacation on a base on one of Jupiter's moons so we get a fantastic view of that gas giant.
Space is where us humans belong-out there wandering among the stars. I just wish NASA didn't turn into another wasteful bureaucracy and focused instead on creating better technologies for deeper space exploration.
@Turbo Two Tone : It provides 300MW of power, yes, but its VIA kinetic energy on an atomic scale. I dont know that we have any viable means by which to produce usable electrical power from that reaction. Its only useful in this aplication as reaction mass in microgravity... in a vacuum.
Sorry to double post, but for reference, fission fragments (whose kinetic energy is deposited as heat energy in coolant mediums in fission reactors to produce power) have on the order of 150+ MeV, depending on the isotope used, along with around another 50 MeV from various other particle releases resulting from fission, for a total of about 200 MeV. Thats in comparison to the reported ~9 MeV (2.9x3)you get from this process. I imagine it would be difficult to attain usable coolant temperatures at this smaller release scale.
@Golimaaar...don't be too hard on NASA, they have done great things, will do more great things, on their own and in cooperation with private enterprise (which wouldn't have much of a chance with out NASA's help), NASA can't help being a bureaurocrat, however, it is still the best spent tax dollars ever
put that 'motor' on a turbine and use it as a spinning power source like they use water in the hoover dam.
thus solves the 'cant get hot enough' problem as stated by iambronco
eh? eh? :D
"11 grams can produce 300MW of power? Why worry about Spacecraft when this would solve the energy crisis?"
11 grams and a laser, which wont power itself.
Also, isn't this similar to the ion engines where you are basically ejecting small particles to generate tiny amounts of acceleration?
So you can attain high velocities if you have a long time but your trip to jupiter could be half your life.
Dear Popsci: many of your readers are adept at sceince. Please give us information that we might actually want to consider.
"11 grams of boron could produce as much as 300MW of power"
watt= power = energy/time. If the discharge is fast enough, the amount of energy could be equivalent to that stored in a AA battery.
The ENERGY that can be released from 11grams of boron would be interesting to know. A power level from a finite fuel is completely meaningless without the discharge time; useful only if you're talking about a powerplant (which implies that power release is constant.)
The answer is likely why such an induced fusion reaction hasn't be considered as a reliable power source.
It does seem similiar to ion thrust engines, but it has one key difference, if you have a ion at speed that repels a magnet, the magnet is 'pushed' in the direction that the ion was travelling. With normal ion engines the magnet pushes the particle which puts an equal and opposite force on the magnet; with this the ion's already have speed (very fast actually) and it some cases the ion's leave and are given more speed by the magnetic field, and in other cases the ions decay and go in the other direction, deflecting off the magnetic field and pushing the magnet along.
Actually now that I've said all that, and taken into account that when the ions decay forwards they push the plate backwards, and then the ions need to be deflected backwards, and they need to be deflected backwards at a higher velocity than they decayed, to achieve a net thrust from those ions, this engine doesn't appear to be as efficient as an ion plasma engine. No wait, Distance matters in magnetic fields! Just remembered that! Read next....
When the particles decay they are much closer to the speed of light than we can accelerate them, if the magnetic containment field is strong enough so that the forward particles can't punch through it, then the forward particles are going to come to rest VERY VERY close to the strongest part of the magnetic field. The short distance between the particle and the field will cause the particle to 'bounce' back at nearly the same speed it entered the field, which is far faster a speed than we can accelerate the particles to.
TL;DR I know BUT Summary, So the idea is that the particles when they decay are moving faster than we have the technology to accelerate them to, and after they bounce off the magnetic field they exit in uniform direction at a velocity much higher than we can accelerate particles to. Very good particle thrust engine.
@brian144 I think the use of volts is accurate in the context that that is the output power of the design that was exampled, not the output power of the boron itself. If I were to measure the potential energy there I would use joules, but if I was talking about the output power of a design of an engine I would probably use watts to describe output, and joules to describe energy storage. Will agree it was a bad sentence.
This is infuriating.
You people cant see what a complete waste of money and resources space exploration is STILL??? STILL???
Thanks to all of you who want clean energy here at home instead of wasting TRILLIONS of dollars per year on ways to waste and burn through all of our resources in the biggest hoax and robbery in history. All your gold and precious metals, all your hydrogen, all of your money, its all feeding people laughing at you calling you sheep and cattle.
Send them all to Mars. Good luck on terraforming it because you dont deserve to live on Earth you locusts.
Everyone seems to be missing a MAJOR Key factor, this type of drive *ONLY* works in Zero Gravity. It follows the same principles of vector adjustments currently used by our space craft, since there isn't anything in "Space" to push against, it's the release of energy pushing on the craft that causes the movement. So the proposed drive is driven by this "push" caused by the reaction itself, not by the particals being exhausted out the rear. The direction of the exhaust also controls the direction of the "push" caused by the release of this exhaust, causing it to be more controlled, but in essence you could have this reaction in open space right behind a craft and it would still push the craft with control of the direction of that push being more or less random.
To address the power needs for the computer and laser systems, that's a secondary system, since the craft would still need some sort of surface to orbit launch, as well as vector adjustment engines/thrusters, the big positive with this drive is that it would use a few thousand pounds less of fuel that would normally be required for any deep space travel. And saving on weight putting it into space, saves on cost, and ultimatly makes it more feasable.
All saying "use this tech to solve the energy crunch", the wattage estimate is simply an analogy. In an atmosphere, this process would do nothing more than make pretty sparks, the net outcome in force would not have the power to move the laser used to start the reaction, let alone power a turbine... think of it this way, try to push boat with your hands and make it move, when it's on land. Not going to happen, but while in the water, pushing a boat by hand is quite easy, now apply that to an object with zero friction... and you might be able to understand a little better.
Playing Devil's Advocate since 1978
"The only constant in the universe is change"
-Heraclitus of Ephesus 535 BC - 475 BC
VASIMR is essentially an ion engine, and a 200MW version can get us to Mars in 39 days... I'm assuming a 300MW ion engine with similar acceleration characteristics could cut that time to about 20 days.
Now lets consider fuel. 11 grams is nothing, thats about the weight of two US quarters (currency). What if it carried a pound of fuel? Thats a little more than 453 grams. Lets consider it will burn (1) fuel to go (2) fuel to return and (3) wants to keep some fuel unspent for unexpected situations. So of that lets say it burns 200 grams to get there, 200 to get back, and keeps 53 in reserves. If for every 11 grams you get 300MW, 200 grams will yield ~8GW (that's GIGAWATTS!!!). This makes transit time to Mars approximately 1 day.
However, considering you'd be accelerating 50% of the way, and decelerating the other 50% of the way we are talking EXTREME forces acting on the body. So much that the typical concept of an astronaut floating in zero-g in the space shuttle as it orbits the Earth simply won't work. Unless we invent the fabled Star Trek intertia-dampening system, we'd likely end up submerging our astronauts in water which might (speculatively) protect them.
But water makes the craft very heavy, even if only a portion of the craft were designed to carry/protect the crew during high speed journeys were to be filled with water, it'd add several dozen tons. The extra weight slows the acceleration, so maybe 2 days to Mars.
And lets not forget these types of engines do nothing for atmospheric flight, so the vessel would need to carry a smaller shuttle (new generation of space shuttle's, anyone? I vote for the Skylon!) to allow the crew to actually land on Mars, again, more weight, less acceleration, 3 days to Mars. But that's no worse than driving across country!
While you guys are free to dream on all you like, I find it naive to think that 11grams of something gets you 300MW of energy as in equivalence :)
For your further understanding: 11grams = 6 SD memory cards (I've actually weighted these just now) :)
Sorry to burst your bubbles. Have fun!
true but imagine that those were micro SD memory sticks carrying 32 gb each. which is possible. 32x8=256. a lot of memory(300MW of power)in small micro SD cards(11 grams). instead of having a heavy old external hard drive which weighs 2 pounds.
@JediMindset: I get what you're tying to say but that would apply to battery storage of energy.
In terms of 300MW, here is a small calculation to aid you further: One person using a bicycle generator can do around 60 watts/hour (the person must pedal at a rate that demands good physical shape). If you were to generate 300MW using the same person and setup, you would need roughly 5,000,000 hours (continuously) which translates to roughly 570 years. Deduct the energy required to keep this person pedaling and you are going to add a few dozen years :)
So hope you can better appreciate the 11grams worth of 300MW is not going to happen.
wow 570 years?! incredible. you right. it seems that i are not even close to packing that much. makes sense.
some one please slap cadillac with a dead fish...
The idea described in this article was actually first mentioned in a testimonial from Bob Lazar, after his Area 52 debriefing. That is exactly how he described the inner workings of the UFO propulsion.
I have invented also a novel propulsion system. It's an electro-mechanical engine, which means it converts electricity directly into mechanical force instead of using fuel. It's a novel concept and it's hard to explain how it works and creates thrust because some people (as I expected) told me it violates conservation of momentum. In theory yes but in practice I don't think so. I hope I will have a prototype of it fabricated and put to test soon. You may check it out on my website:
-Hossein Nabipour, inventor of the first practical interstellar propulsion engine
Ok. I get the physics of this. Nothing new, just new application of the boron isotope. My question is about the foil. Fatigue versus the laser driven stress in the foil, in the cold of space. Also, this fuel cycle is dependent on some level of saturation overall, in every shot. It's unrealistic to think there won't be decreasing efficiency over time, and the ultrathin nature of the foil is working against both of these factors.