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VASIMR Plasma Thruster To Be Tested Aboard ISS
Toren Altair brings news that NASA and the Ad Astra Rocket Company finalized a Space Act Agreement earlier this week to test the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) on the International Space Station. The agreement hinges on a series of requirements for the thruster's performance and efficiency in ground-based tests. "The primary technical objective of the project is to operate the VASIMR VF-200 engine at power levels up to 200 kW. Engine operation will be restricted to pulses of up to 10 minutes at this power level. Energy for these high-power operations will be provided by a battery system trickle-charged by the ISS power system. These tests will mark the first time that a high-power, steady-state electric thruster will be used as part of a manned spacecraft." Reader clarkes1 points out related news of a runway trial for Virgin Galactic's WhiteKnightTwo, the mothership that is designed to carry SpaceShipTwo from the ground to 50,000 feet. A very brief video shows the oddly-shaped plane moving down a runway under its own power.
Maybe it is strong enough, but with the only join between the two hulls being a wing, I don't think I would want to travel in it or under it. Reminds me of something I heard in a documentary about the competition for for the joint strike fighter between Boeing and Lockheed Martin. One of the LM guys said something like a principle of winning many of these competitions is that it has to look like fighter plane. The idea being that theres looked more like a fast scary fighter while the Boeing fighter had that giant scoop and didn't look like a 'traditional' fighter. White Knight 2 doesn't look like something that should be safe... at least to me.
-- I ignore anonymous replies to my comments and postings.
Indeed, the power supply problem does exist, and is actually the limiting factor in the performance of ion thruster engines and electric propulsion in general. That limitation actually causes very high specific impulses to be undesirable as the power supply weight savings exceeds the mass savings in propellant. The ideal specific impulse then becomes an optimization problem.
That said, my point is that there are particular applications for which electric propulsion is better than conventional methods (long-distance robotic missions, to pick one), and there are other applications in which chemical propulsion is better than electric propulsion (such as moving a satellite from low-Earth orbit to geostationary orbit... we don't want to wait months for that to occur!) Kind of like in anything involving engineering, you have trade-offs that you have to consider for a particular mission. But assuming that big liquid propulsion rockets are the solution to all the problems is rather lame.
After 8 years of crews testing obscure basic science, they finally have the first tentative approval for the most obvious experiments some time in the future. Incredible.