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NASA Wants Revolutionary Radiation Shielding Tech
coondoggie writes "Long term exposure to radiation is one of the biggest challenges in long-duration human spaceflights, and NASA is now looking for what it calls 'revolutionary' technology that would help protect astronauts from harmful exposure. 'It is believed that the best strategy for radiation protection and shielding for long duration human missions is to use electrostatic active radiation shielding while, in concert, taking the full advantage of the state-of-the-art evolutionary passive (material) shielding technologies for the much reduced and weaken radiation that may escape and hit the spacecraft.'"
Nope. Completely different type of radiation.
In space, the main problem (unless your spacecraft is nuclear-powered) are high energy cosmic rays.
In Japan, the issue is with radionuclide contamination.
Also, NASA's looking for a way to keep external radiation out - in Japan they're trying to contain radioactive substances within a vessel that contains superheated water that is pressurizing it, water which is unfortunately radioactive (resulting in the steam being radioactive if they vent it)
retrorocket.o not found, launch anyway?
Alpha particles are blocked by a thin sheet of paper, so no risk to astronautics as long as the alpha particle producers stay outside the craft
Secondary gammas release on impact. Ouch.
Beta particles are neutrons
No electrons.
Gamma rays are an electromagnetic wave, like light, and hence also can't be deflected by an electric field.
There are other types of radiation, but I got the feeling they were rare (ie. not found except in particle accelerators) - can someone correct me?
Not really. nuke radiation is pretty much defined as alpha beta and gamma "waves/particles" plus our mostly artificially generated pal, the neutron. If we could make muons or other particles in bulk we'd probably add those. Delta waves and stuff are only found in star trek technobabble.
The concept of "rare" is kind of vague in particle physics.
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
Active shielding will only work for Alpha, Beta, and high energy Protons. It will do nothing for Neutron, Gamma, Xrays, and so on. For Neutron you could us a material with lots of Boron in it but I am not sure if Boron only captures some energies of Neutrons effectively or all of them. If it only captures thermal neutrons then you could combine it with carbon and have pretty efective material. But when you are talking about high energy Photons the only thing that I know works is mass.
So pick your radiation and there will be a different way to shield it.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
Well, not to put too fine a point on it, but NASA wants active shielding for the sorts of natural radiation astronauts encounter in space. Cosmic rays, solar flares, and the Van Allen radiation belts. All of which are charged particles.
As a general rule, one only encounters neutrons, gamma rays, and x-rays from artificial sources, such as nuclear weapons and nuclear power plants.
So unless NASA is contemplating starting a space war with alien invaders from another solar system, they will be well served by active shielding.
And . . . jeeze: "Water, when exposed to vacuum, freezes."
No, it evaporates.
Or to be more precise, it evaporates, and the loss of heat due to the latent heat of vaporization results in cooling, which in turn results in freezing when the temperature gets sufficiently low (after which point you will still have some cooling due to sublimation of solid ice)..
The coolant in nuclear power plants is radioactive *mainly* because it has small amounts of insoluble stuff (commonly called "crud") suspended in it and soluble stuff dissolved in it that are radioactive, mostly Na-24 and Cl-38. Just a teeny little bit of cobalt from alloys in valves and pumps getting into the coolant and getting activated to Co-60 contributes a majority of the long-lived radioactivity of reactor coolant. There are some water activation products but they are smaller contributors and have short half-lives.
...the future crusty old bastards are already drinking the Kool-Aid.
Check out "Project Pluto" some time. It was a nuclear-powered ramjet cruise missile. At some point they realized that simply flying the dirty engine at low-altitude mach 3 over anything was about as bad as actually bombing the target. The stuff the engine spewed out the back was so bad that there was no safe way to flight test it, and you could never fly it over a friendly nation on its way to a target.
The living have better things to do than to continue hating the dead.