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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.'"
Seems to be the first line of defence for many...
A feeling of having made the same mistake before: Deja Foobar
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?
With the exception of Project Orion, all of the nuclear propulsion concepts I've read about, and even the actual trials made in the 1960s, have much lower thrust than chemical fueled rockets. In the case of ion and plasma thrusters, vanishingly little thrust. Even in the case of fission/thermal rockets (e.g., NERVA), only about a third of the thrust of chemical rockets. They are less suitable for getting stuff into orbit than chemical rockets.
Once you're in orbit (or beyond), thrust counts for much less than exhaust velocity.
And as for Project Orion: Yeah, some of the proposed designs could heave a pretty damn big ship into orbit, But the fear of fallout from hundreds of little atomic bombs going off in the atmosphere is anything but irrational. One of the principles of the project, Freeman Dyson, specifically stated that the risk wasn't worth it. (I mean, maybe if there was a big asteroid on the way . . .)
And . . . jeeze:
"Water, when exposed to vacuum, freezes."
No, it evaporates.
The one downside of nuclear rockets is that if we had another Challenger-esque disaster, this time with, say, plutonium fuel, the repercussions would be much, much, much more immense. Just to be sure, we'd have to launch all rockets from tiny little atolls in the middle of the ocean.
Except you wouldn't use plutonium for fuel.
When NASA were planning to launch NERVA rockets the flight path would have been south from California so that any launch failure would either dump the NERVA into the ocean or the Antarctic. And since it would have been boosted by a conventional Saturn V, there wouldn't be any really nasty radioactivity until the NERVA started firing late in the launch.
That said, using nuclear fission rockets for launch from Earth still seems pretty optimistic to me.