Vid 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 available on YouTube:

The recycled-materials space thruster was assembled Dr Oleg Batishchev and his team, of the MIT Department of Aeronautics and Astronautics. Batishchev's mob are working on a heavily simplified version of the Variable Specific Impulse Magnetoplasma Rocket (VASIMR), which might soon be used to adjust the orbit of the International Space Station - or one day carry astronauts beyond Mars.

Batishchev believes, however, that full-on VASIMR plasma drives are too complex for use on the most common of humanity's spacecraft today - normal Earth-orbiting satellites. But satellites need a propulsion system. They carry small chemical rockets, used for adjusting their orbit - either to keep on track, to change what ground they pass over, or to avoid collision with other objects in space.

When a satellite runs low on fuel, it must normally use the remainder to re-enter the Earth's atmosphere under control and splash down safely in the ocean - though this doesn't always happen. Either way, manoeuvring fuel is the main limiting factor on a satellite's useful life, so it would be good to have more fuel efficiency.

That's where Batishchev & Co's cut-down VASIMR plasma drives come in. Like VASIMR, they eject reaction mass using electrical power rather than a chemical reaction in the fuel itself. This permits the exhaust velocity to be much higher, getting a lot more poke out of each gramme of reaction mass.

"The idea was that a rocket based on the first stage VASIMR could be small and simple, for more economical applications," says Batishchev. Small indeed: the team's prototype "would fit in a large shoe box".

The machine is known as the "Mini-helicon", and works by ionising nitrogen reaction-mass in a quartz tube using a radio antenna coiled around it. Magnets enclosing both systems control the resulting plasma.

"The plasma beam exhausted from the tube is what gives us the thrust to propel the rocket," Batishchev says.

The MIT rocket scientist released the above vid yesterday, of a "fun" prototype fashioned by his crew from a glass bottle (acting as the quartz tube) and a Coke can (replacing the antenna). Apparently it actually worked in the MIT vacuum chamber, producing a (very small) amount of thrust.

"This shows that this is a robust, simple design," argues Batishchev. "An even simpler design could be developed." (Possibly made out of yogurt pots?)

Batishchev doesn't see his tech getting into space any time soon, saying that certification issues are a problem. His research is funded by the US Air Force: one might note that famed Pentagon crazytech agency DARPA are also interested in the general idea.

There's more from the MIT team, including pics, here. ®