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NASA Ground Tests Ion Engine
herda05 writes "New Scientist reports from a press release by NASA on a successful ground test of the HiPEP (High Power Electric Propulsion) ion engine, which is the first 'major milestone' for Project Prometheus. Also some pictures and more info on the HiPEP engine."
Is there really a lot of xenon gas in outer space? Wouldn't ionizing hydrogent work a lot better? And, is it really a vacuum chamber if it's filled with xenon gas?
"Freedom means freedom for everybody" -- Dick Cheney
"NASA Ground-tested an Ion Engine" would have been a less headline-ish way of saying it.
"Murphy was an optimist" - O'Toole's commentary on Murphy's Law
This I think makes it only usefull for long flights. No tie fighters. Fortuanly real space flight has a lot of long flights.
MMO Quests are like orgasms:
You may solo them, I prefer them in a group.
Before anyone has visions of nimble fighters, we must remember that ion engines have extremely low thrust. A quick calc based on the numbers in the article, which I hope I did correctly, suggests that the thrust is only about 0.3 Newtons (1 ounce for you Imperialists). What makes these engines exciting is that they can sustain that thrust of years. Estimated fuel consumption is only about 14 grams per hour.
Slow and steady wins the race.
Two wrongs don't make a right, but three lefts do.
One of the earlier "nuclear" test engines was this puppy, the nuclear thermal rocket. If you have seen a video of it when it was being tested, you would know that that thing is one mighty beast. The soviets also attempted to design one (both the Soviet and the American versions had the purpose of getting people to mars) which looks a lot cooler. I would love to have a model of that sitting on my desk. :)
Anyway, this nuclear propulsion is somewhat related to the newer Xenon method albeit with lower specific impulse but much higher acceleration.
I had but a simple dream, to destroy all humans.
Yep. And considering current "MMRG" units and SRGs(check out their homepage- they're basically two of I-dunno-how-many nuclear-powered generators NASA has at the moment) top out at 100W per module, well...
I think the problem is that NASA, rightly so, is extremely nervous about putting nuclear stuff into orbit, because of the frequency with which these things blow up. So it tends to be very simple, not very efficient(the MMRG only captures 100 out of 250w produced), and not very powerful. For example, the MMRG modules produce heat just by natural decay, and they're designed to survive a crash as a whole intact(nasa notes that previously they were designed to burn up, but are now designed to stay intact- probably because things don't always get high enough to burn up).
Problem is, even with solar power- which starts getting pretty sparse(why they came up with the nuclear power sources)- a large(sheet of plywood sized) solar panel isn't much, at least on earth(you get more power outside the earth's atmosphere). It'd take a LOT of that sized solar panels to power such an engine. Probably somewhere above 50 for starters...
Please help metamoderate.
Ion propulsion works very differently than any other type of normal rocket. The idea with ion engines is that they're able to take individual atoms of their "propellant" and accelerate them to high velocities, using electricity as the energy, rather than some sort of chemical reaction.
Rockets in space work by taking some mass and throwing it in the opposite direction you want to go. Imagine yourself floating in space holding a bowling ball. You wouldn't have to push the ball away from you very hard to get yourself moving, since it's very heavy. But what if you only had a ping-pong ball: to get yourself moving quickly, you'd have to "throw" the ping-pong ball away from you very very very fast, to make up for its very small mass.
Chemical rockets take some combination of chemicals that react strongly together, creating heat. The result is a hot gas at high pressure, which blows out in the direction of the rocket nozzle, providing thrust the other direction.
The xenon ion engine takes xenon gas at very very low pressure, ionizes the atoms so that they're electrically charged, and then uses electric force to fling them at VERY high speed out into space. The velocity is much higher than in any chemical rocket. But ion engines aren't very strong -- the process works with just a little tiny bit of xenon at a time, so the engine as a whole winds up giving just a very gentle push. But since not much xenon is used up, the xenon that you have will last a LONG time.
That's the "specific impluse": a measure of how much a rocket can push you "per pound" of fuel. This page says that the space shuttle's chemical engines have a specific impulse of 460. This latest ion engine has a specific impulse of 6000!
So with the same weight of fuel, the ion engine would get you going about 13 times faster by the time you used up the fuel.
- Peter
INsigNIFICANT