MIT boffins fashion working plasma rocket from Coke can MIT astro brainboxes say they're on the track of tech which could greatly prolong the life of satellites, as well as helping them avoid banging into each other. They have illustrated this by fashioning a crude plasma thruster out of a Coke can and a glass bottle. Needless to say, the MIT vid of the Coke bottle-rocket is …
Where's the pork in that? Self-evidently the technology is not going anywhere soon.
OTOH there's quite a lot of basic research that could be done in the field of plasmas - were it not for the fact that it threatens to overturn several well-filled prok barrels, such as the search for the fabulous gravitational waves. So who's up for a real scientific Challenge?
we're closer to building a Bacon-and-Beans Megarocket! Commander Keen will be able to save the galaxy using only bits from his kitchen (and his brother's football helmet)!
Wow, I feel old...
I wonder if I could build one of these in my kitchen- having a small plasma engine sat burning away would be sweeee-eet.
But seriously.
"Like VASIMR, they eject reaction mass using electrical power rather than a chemical reaction in the fuel itself. "
And every other ionised particle thruster system, Hall and the the conventional one on several Hughes (and other) comm sats for station keeping and I believe several more besides.
I'd love all these groups to put up 2 things. What's their power input to thrust ratio (current and potential) and their maximum size IE are there inhearent problems with the physics which stop a design.
Of course if the rocket test on the ISS is actually a complete working prototype and actually fires that would be a much more serious proposition.
Clearly must have read "Q-Pootle 5" by Nick Butterworth
see: http://www.amazon.co.uk/Q-Pootle-5-Nick-Butterworth/dp/000664712X
and to quote the review Amazon use
A burned-out rocket booster puts a kink in pudgy, green Q Pootle 5's plans to make it to his friend Z Pootle 6's birthday party on the Moon. That booster looks remarkably like a tin can in Butterworth's simply drawn cartoons-and indeed, after a forced landing on Earth, Q Pootle 5 finds that a more or less empty can of cat food makes the perfect replacement part. Once Henry the cat has finished his supper, of course, he makes certain it is empty and it does the trick. No, not exactly rocket science, but the pictures are well stocked with page-filling disaster noises-including a four-page, giant-sized "sssscccrrreeeeeeeee . . ." that is Q Pootle's landing-and helpful earthlings, mostly of the four-legged variety. An unfolding, poster-sized party scene brings up the rear of this droll close encounter of the silly kind. "(Picture book. 5-7)" (Kirkus Reviews)
There is a classic catch 22 concerning new technology in space, everyone wants to have better tech available for their birds, but nobody wants to fly anything but space-proven hardware. This is understandable considering the megabucks it takes to buy a launch (it is my understanding that the rule-of-thumb in space business is that the payload tends to be about the same price tag as the ride you are using to put it in space, so the whole package is now 2*megabucks). With so much at stake, the imperative is to leave as little as possible to chance, as recent events underline:
http://www.theregister.co.uk/2009/02/24/oco_launch_failure/
By being willing to flight test new technology, government space programs (be they civil, as in NASA, or military, as in DARPA) can get some of the maximum bang for their buck by proving out technology that both they and everyone else can get to use. Note that this gives you the classic definition of a "public good" (non-rivaled and non-excludable) where government involvement makes the most sense. I would also note that this is not without recent precedent, from 1998 to 2001, NASA operated Deep Space 1, whose primary purpose was to prove out new technology (it was successful at this, several of the technologies it pioneered have since been used on other missions). High specific impulse drives like this are particularly important because they can give an exponential improvement in what you can get from a given amount of reaction mass. We need more of this.
Good , I'm glad I'm not the only one who thought of QPootle5. A very fine book. Forget flying cars , I want my own spaceship easily repaired using materials available in the home.
I guess as it was run in a vacuum chamber there was no smell of caramelised soft drink afterwards.
I was at an open house at JPL, where one of the "science fair" displays (think of a JPL open house as an adult version of the science fair...) was a plasma thruster design, happily spurting away in a vacuum jar. It was constructed out of similar "junk box" stuff, and used ionized polyethylene plastic as the propellant. The JPL model used a fairly small lab-bench power supply, charging a couple of caps that then discharged to ionize the propellant and fire off the resonant cavity to accelerate the particle stream.
The design was a prototype for - you guessed it - a cheap, long-life stabilizer motor for a satellite...
(Not knocking the MIT effort at all: it's just that this has been kicking around for a L-O-N-G time...)
It is a similar idea, but different in how the thrust is generated. In an ion engine, you are applying a potential difference to accelerate the (charged, by definition) ions. In this plasma rocket you are using a specific frequency of RF to form and then excite the plasma. The magnetic fields enclosing the plasma partially effectively becomes a magnetic rocket nozzle, with the excited plasma "wanting" to exit at high speeds.
Two advantages in this approach that I have heard mentioned are: 1) You don't need a neutralizer (to keep your rocket from acquiring net charge), because there are an equal number of electrons and singly ionized atoms emitted. And 2) There is no need to insert anything like a grid into the exhaust stream, which you need to do in ion engines to give you that potential difference. Since the grid is prone to erosion from this and is a potential failure point, either from that erosion or from something like clogging. This makes the engine more robust.
What wasn't mentioned and I am not sure why not, is that an ion engines are limited in the size of potential difference you can apply (use too much and you will just get arcing). I don't see where this limit would have a counterpart for the plasma engine (although I might be missing something there).
Nothing new here, move along. Geeze! I even worked on ion thrusters up to 30 cm in diameter in the late 70's at Hughes that had over 98% efficiency. (1 Joule in, 0.98 to 0.99 Joule ended up in the thrust beam). This technology has not made it into wide scale use due to issues having nothing to do with the thruster technology. The Hughes division is now part of Boeing:
http://www.boeing.com/defense-space/space/bss/factsheets/xips/xips.html
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