Fusion Thrusters For Space Travel 192
kgeiger writes "John J. Chapman, a physicist and electronics engineer at NASA's Langley Research Center, envisions a laser-pumped fusion drive. Chapman estimates the drive can produce thrust 40 times more efficiently than existing ion engines such as those on the Dawn mission now exploring the asteroid belt."
Re:research! (Score:2, Interesting)
My math may be wrong, but... (Score:1, Interesting)
2.9 MeV per alpha particle * 100,000 ~= 0.00000047 joules
I'm not into engine building, but that seems like a tiny amount of force for 87.2 KWH.
Re:research! (Score:4, Interesting)
1) SpaceX's rockets? The engines were developed by NASA in the 90's, but squelced by 1996 CONgress.
2) Perhaps SpaceX's tank's? Again development by NASA, but squelced by 2001 W/CONgress destruction of X-33.
3) Inflatable space stations? Transhab that was crush by 1996 CONgress, but allowed into private enterprise by Clinton
4) Laser Drilling? Crushed by 1996 CONgress, but allowed to go to Colorado Mines by Clinton.
5) VASIMR? Crushed by 1996 CONgress, but allowed to go private by Clinton.
The list goes on and on and on. NASA does a LOT of R&D, but it is CONgress and typically short-sighted pres (nixon and W being the worst 2) that destroy it. You will be hard pressed to find any ORIGINAL SPACE R&D by private enterprise that is NOT an off branch of something that NASA came up with and funded.
Re:It seems more fission than fusion (Score:4, Interesting)
When the proton hits the boron-11 nucleus they fuse giving an excited (that bit's important) carbon-12, which in very short order (sorry, the exact time escapes me) splits into a helium nucleus and a beryllium-8 nucleus, which in turn splits into another two helium nuclei. So what you have in effect is a fusion-fission reaction but the fission part isn't usually mentioned - something to do with OMG nuke! types, perhaps?
However, I suppose it is true that all of the energy is coming from fusion, as 12C -> 4He + 4He + 4He is exothermic. (The reverse reaction is an energy source for stars under some circumstances.)
Actually, the triple-alpha process, which produces carbon in some stars is closer to this:
He + He -> Be
Be + He -> C
I expect that the probability of a 3-body collision between 3 helium nuclei is so vanishingly small as to be insignificant, but hopefully someone who knows this subject well can fill in that particular blank.
As for why the carbon that gets produced doesn't immediately decay like the one made in a p+B11 fusion reactor, I couldn't say as IANANP (just an interested layman) but I imagine it's something to do with that business of being in an excited state I touched upon earlier.
P.S. A dictionary isn't a good place to start learning about nuclear physics; try an encyclopaedia instead. In fact, here [focusfusion.org] is a good article, which was the second result Google gave when I searched for p+B11. To address your issue with particles: yes, more atoms come out than go in, but the number of nucleons remains the same.
Re:Fiscal Sanity? (Score:5, Interesting)
We spend the equivalent of a huge forest of money trees on USELESS aggression; bring those troops and ships home, destroy deployed equipment in place, sell it to the locals, or bring it home if practical, leave the military brought home employed for a strong standing defense, and (a) we'd be acting morally for the first time in decades and (b) the money spent on the standing army, now home, would go right back into our OWN economy, and (c) we'd have huge overall spending reductions we could apply to the debt and perhaps once again, someday, have money to spend for our actual benefit.
Our budget problems are 100% solvable. All you need to do is get the cowards out of congress. Somehow.
Point It at the Earth (Score:4, Interesting)
We should have these power collectors/transmitters in orbit around the Sun, pointed down at the Earth to collectors floating on the seas. Where they could electrolyze water, or any of a number of other ways to get the energy back to the land where it can be consumed. Emissions free, vastly more power than we can use for the foreseeable future.
The beams would have to be only a few times the intensity of sunlight, but shine all day/night (courtesy of geosync relay satellites) over a few dozen square kilometers on each station. No danger from a beam missing the target, though extra protection added by laser interlocks back from the surface to space that drop both up and down beams when the down beam goes off the target.
That system would require several $billion, perhaps several hundred $billion, investment. But at $0.01:KWh, and $100B is only 1KW:m^2 * 3intensity * 36Km^2 * 6stations * $0.01:KWh = 22.5 months payback time. That's better than 50% ROI, on hundreds of $billions. Plus the value of eliminating emissions, terrestrial fuel production and distribution, energy wars and corruption. And regaining the envy of the world.