[X] My Assistant

[Guest_DonPMitchell_*]

OK, I'm in that unpopular camp that believes that the Breakthrough Propulsion Program should never be funded again -- we should not spend any money on Heim Theory, gyroscopic antigravity, space elevators, antimater engines, Bussard ramjets, black hole engines, UFO research, and zero-point energy. I have a radical alternative proposal.

Instead of using Wired Magazine physics to get to the stars, I'd like to use The Feynman Lectures physics to get to the stars. I propose building a craft powered by atomic fission. The engine would be a high-current linear ion accelerator, consisting of a superconducting niobium cavity resonator like this one, to get a nice healthy relativistic exhaust velocity.

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Next, we crack open a good book, like Taylor & Wheeler's Spacetime Physics, and figure out how long it would take to get a real spaceship to Alpha Centuri. What is the relativistic form to Tsiolkovsky's Rocket Equation? (OK, T&W does that for you) How much Plutonium would it have to carry? How much ionizable reaction mass?

I guarentee you, this hypothetical ship will get to the nearest star long before anyone invents a warp drive. Maybe I should ask NASA for $1.6 million, to develop this idea?

[jsheff]

Here's another idea:
As someone here previously mentioned, the problem limiting power output from a nuclear fission reactor is operating temperature. Power is proportional to temperature, but beyond a certain temperature, the core melts.
There has been an idea advanced called the gaseous-core fission reactor, where the core is undergoing fission in a plasma state, so operating temperature is no longer a limitation. I remember reading a book by a propulsion engineer named Hunter back in the sixties (which I wish I could find again), and he worked out some of the performance aspects of such a reactor. You'd have the uranium in the form of a plasma that reaches criticalilty inside a chamber with "glass" walls, that it does not come into contact with. Instead the plasma simply reaches criticality and then gets exhausted out the back of the ship before it comes into contact with anything it can melt. But unlike in Orion, the fissioning material does not do the pushing. Instead - and here's the key point: the plasma heats fuel in a surrounding chamber by the radiative flux going through the "glass" walls. The heated fuel then exhausts out the back (along with the uranium plasma) and produces thrust.
He calculated that such a ship would be capable of speeds of 100,000 - 1,000,000 feet/second. It could do 1 AU (Earth-Sun distance) in about 11 days. At such speeds you don't need to travel along a long curving Hohmann trajectory to reach another planet, and you don't have to wait for the planets to come into position. The trajectory of the ship is esssentially a straight line from one planet to another. Such a ship may still be way too slow to travel to Alpha Centauri, but it would open up the solar system to commerce. Pretty cool.