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Plasma Rocket Successful Full Power Test
Matt_dk writes "VASIMR is a new high-power plasma-based space propulsion technology, initially studied by NASA and now being developed privately by Ad Astra. A VASIMR engine could maneuver payloads in space far more efficiently and with much less propellant than today's chemical rockets. Ultimately, VASIMR engines could also greatly shorten robotic and human transit times for missions to Mars and beyond."
In theory, we could always do that, in practise I don't think we'll ever do that. Getting anywhere really fast burns a ton of extra energy, plasma drive or not. Most of the really long-distance missions haven't accelerated to that speed, they've done a slingshot trip around jupiter or something like that. Even on a Mars mission we're really just waiting for Mars to be in the right position to leap orbit and minimize the rocket use, not plotting a course or going from full impulse to full stop in seconds like you see on Star Trek. It would still cut a lot of costs but the cheapest route is still the slow one.
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OK, this is a classic plasma rocket - ionize an inert gas (here argon) and push it out with an electric field (not done in this test). So what are the numbers? How much argon are they using per unit thrust? How much electric power does this take. Is 200KW the input, or the output?
You still have to carry reaction mass; that's the argon. So you can't just keep boosting as long as you have power.
It's not a bad idea, but it's not clear how good the implementation is.
The same incorporates "variable specific impulse" so you have to use a range.
3,000 seconds is comparable to a ion motor.
30,000 seconds is better than the predicted Isp of the Orion nuke-bomb drive.
I thought it seemed fairly straightforward.
1. the hotter the flame, the more thrust you have and the more efficient the thrust. Your limit is when it's hot enough to melt the rocket's nozzle.
2. Since it's a plasma, you can control it with a magnetic field, to the point that its heat won't affect the rocket's nozzle.
More efficient=less fuel needed. In addition to keeping the heat away from the metal, being able to control it with a magnetic field means you don't have to have a moveable nozzle to steer the thing, making it possibly simpler than traditional designs.
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