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New Ion Engine Being Tested
Dr Cool writes "A new design of spacecraft ion engine has been tested by the European Space Agency which dramatically improves performance over present thrusters and marks a major step forward in space propulsion capability. Ion engines are a form of electric propulsion and work by accelerating a beam of positively charged particles (or ions) away from the spacecraft using an electric field. ESA is currently using electric propulsion on its Moon mission, SMART-1. The new engine is over ten times more fuel efficient than the one used on SMART-1."
The low torque is not a big concern. In space you can rotate a spaceship any way you want by using gyroscopes.
Conservation of angular momentum says that if you turn on a gyroscope, the spaceship must start rotating in the opposite sense so the total angular momentum is the same as in the beginning. At some point you stop the gyroscope and the ship stops rotating.
Think momentum, not energy.
I've got a bad attitude and karma to burn. Go ahead. Mod me down.
Not really, what the extra grids are doing are focusing the beams more so that they actually proceed through the grid rather than hitting it. Ions hitting the grids and causing them to collapse over time is the primary failure mode for an ion thruster, so being able to focus it more seems to allow more power to be pumped into it so that the stream is accelerated faster. I guess more grids might allow you to focus it more, but I'd guess that its a diminishing returns thing. I'm doing research with these thrusters (trying to show a particular fluid simulation, which is particularly good with parallel processing, is valid), especially for the reasons the article talks about with the testing. I think im going to try this multiple grid situation and see how it acts later.
Is there any reason that they couldn't just keep adding grids with varying voltages? And why are the last two voltages both low? Wouldn't it make sense to alternate them?
If you put a high-voltage grid after a low-voltage one, the ions would be repelled by it, not attracted. The voltage gradient must go in one direction: out of the thruster. I'm no scientist, but I don't think you'd gain much by adding a third couple of grids inbetween the two with a medium-voltage level. It would probably be more fruitfull to simply increase the difference between the high and low levels.
I assume the last two grids are low for the same reason the first two are high, to prevent errosion.
So while the ESA is desperately trying to generate some positive press to help people forget about their recent failings the good old US of A is putting proven and effective technology into getting back to the moon.
Care to point out some of the recent failure sof ESA?
As a sidenote: the currently only ion drive propulsed moon orbiter is a european one
angel'o'sphere
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
Actually, in many cases you can get where you want to go with little or no thrust at all, simply by riding the elevator up past the altitude of geosynchronous orbit. The higher above that altitude you go, the greater the centrifugal force from being spun around the Earth, so it's just a matter of calculating when to let go of the elevator.
I don't care if it's 90,000 hectares. That lake was not my doing.
Even though the parrent was trying to be funny a space catapult is a sensible idea.
/C
It would drasticly reduce the cost to throw things into space.
One idea is to put a linear acellerator on the side of mount kilimanjaro (strategic position near equator)
and use it to "kickstart" rokets. this way you can get more payload from a smaller rocket that uses less fuel.
You dont have to be an analretentive nitpicker to be a tester.... But it helps