But, since Uranium isn't that expensive, and you don't need that much of it, and it weighs very little compared to the mass of Hydrogen you need for the thing... why bother? Just flush the Uranium out the back to turn the engine off.
]]>Nuclear fission/electric propulsion doesn't make a great deal of sense with current reactor technology for manned applications. A vapor core reactor or something else exotic like that would be needed.
Of course, there is always the engine of my namesake, the Gas Core Nuclear (fission) Rocket.
]]>The new system would make the moon, which is about 239,000 miles away from Earth, a short trip.
I doubt an ion engine would produce enough thrust to significantly shorten the flight time between Earth and Moon, especially if it is used to spiral out from LEO instead of a chemical sling shot. But for Earth->Mars or even further it could make a big difference.
Assumed the 200 000 Mph is delta v, that's about 80km/sec. Hmm interesting, it would have to work at tremendeous ISP to make the dry-weight/propellant ratio big enough (which also means very low thrust, even with a nuclear reactor).
Herakles and the other elements of a Prometheus craft are scheduled for advanced flight development in 2006.
The craft would be powered by an onboard nuclear reactor.
The ion beam produced from xenon gas to propel the craft to speeds of 200,000 mph, 10 times faster than the top speed of the space shuttle.