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The project, in concert with US government agency DARPA, aims to develop pioneering propulsion system for space travel as soon as 2027:
The project is intended to develop a pioneering propulsion system for space travel far different from the chemical systems prevalent since the modern era of rocketry dawned almost a century ago.
"Using a nuclear thermal rocket allows for faster transit time, reducing risk for astronauts," Nasa said in a press release.
[...] Using current technology, Nasa says, the 300m-mile journey to Mars would take about seven months. Engineers do not yet know how much time could be shaved off using nuclear technology, but Bill Nelson, the Nasa administrator, said it would allow spacecraft, and humans, to travel in deep space at record speed.
[...] Using low thrust efficiently, nuclear electric propulsion systems accelerate spacecraft for extended periods and can propel a Mars mission for a fraction of the propellant of high-thrust systems.
Also at CNN and Engadget. Link to Nasa press release.
(Score: 5, Interesting) by VLM on Friday January 27, @01:49PM (2 children)
http://orbit.medphys.ucl.ac.uk/ [ucl.ac.uk]
As per Orbiter game from the turn of the century, orbital mechanics is non-trivial and for various safety reasons they'll want a non-return orbit such that if the thrusters cut out at any point in the mission the craft won't impact the earth. Ironically the human safety people will want the opposite so if the main engine cuts out they can use the RCS thrusters to line up a re-entry so the crew doesn't end up lost in space.
The meta argument about this is its a waste of chemical fuel to haul supplies and too dangerous to use nuclear fuel to haul people, which means you'll "have to" have a much more complicated mission profile. And those usually don't have much of a time limit. So the engineers are confused about "how long it will take" because it'll probably haul something the size of the ISS to Mars "eventually" rather than breaking speed records with humans on board.
Then again, who knows what they'll end up doing.
(Score: 4, Informative) by Immerman on Friday January 27, @03:55PM
Keep in mind that the primary use-case for nuclear engines is interplanetary flights: Where a safe return trajectory is not an option[1], and the desire for more speed is almost entirely because space radiation and microgravity are both slowly killing and crippling your passengers the entire time they're in transit.
We're going to be putting these on passenger craft just as soon as we're sure they're reliable - there's no reason not to.
They'll also be nice for more cheaply getting big payloads there "eventually", but the high-efficiency Hohmann Transfer Orbit route is locked at... I think it's around 9 months between Earth and Mars, regardless of engine type used.
[1] there's no trajectory between Earth and Mars that, if the "arrrival burn" at the other planet fails, will pass anywhere close to either planet again for a few years. At which point it's probably far to late to rescue anyone. And a fast trajectory will be even worse - it could be decades before it approaches either planet again.
It's easy for the moon, since any transfer orbit that's not stopped in lunar orbit is still in Earth orbit and will immediately loop back to Earth. But for interplanetary flights a "miss" will remain in orbit around the sun, with an orbital period that doesn't coincide with either Earth or Mars, so when it next passes either of the planet's orbits, the planets themselves will be nowhere remotely nearby.
(Score: 3, Informative) by Immerman on Friday January 27, @04:03PM
Oh, and as for the danger of nuclear fuel in a spaceship... it doesn't really exist.
You're already flying through a radioactive hellscape filled with far higher energy cosmic rays
It's easy to shield the reactor from the passenger compartment by putting your water tanks between them - every ~7cm of water halves the radiation levels, and it's not going to take much to bring the reactor-sourced radiation down below the ambient background radiation of interplanetary space.
Finally, nuclear fuel isn't substantially radioactive (if it were it wouldn't still exist after 4.5 billion years in the ground), only the nuclear waste and the reactor itself are. So launching fuel into orbit is a non-issue - way less dangerous than launching a probe/rover with a standard RTG into orbit, which *is* highly radioative within its protective casing.