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Giving CubeSats Electric Propulsion
eldavojohn writes "Thirteen picosatellites were launched back in June of 2006 with the price coming down dramatically in the years since. But the Rubik's cube sized devices have no mobility, meaning once they're put in orbit, they stay in that orbit. The big problem is that traditional chemical propulsion systems are too large for ten-centimeter sided cubes weighing a kilogram. A new electric propulsion system designed by Paulo Lozano of MIT might change that. "
"The article explains how it works: 'Lozano's design relies on electrospraying, a physics process that uses electricity to extract positive and negative ions from a liquid salt that is created in a laboratory and serves as the system's propellant. The liquid contains no solvent, such as water, and can be charged electrically with no heat involved. Whereas other electric propulsion systems charge the ions in a chamber on the satellite, the ionic liquid in Lozano's design has already been charged on the ground, which is why his system doesn't need a chamber. Electricity is then converted from the main power source of the CubeSat, typically batteries or a solar panel, and applied to a tiny structure roughly the size of a postage stamp. This thin panel is made of about 1,000 porous metal structures that resemble needles and have several grams of the ionic liquid on them. By applying voltage to the needles, an electric field is created that extracts the ions from the liquid, accelerates them at very high speeds and forces them to fly away. This process creates an ionic force strong enough to produce thrust.'"
CubeSats are the "cheap access to space" needed for research and technology risk reduction that's been needed since the dawn of the space age.. and it didn't require some magical new propulsion method or even new economies of scale in launchers, just good standards and a very big customer, the Airforce academy.
For those of you who find the article a little light on details, here's the scientific paper:
http://sgc.engin.umich.edu/erps/IEPC_2007/PAPERS/IEPC-2007-145.pdf
This preliminary work is now being flight tested.. and, if all goes well, it'll soon be commercially available. When's soon? 3 to 5 years. That's what CubeSats give you, a reduction in lab-to-market from 10 years or longer to 6.
How we know is more important than what we know.
What, we've exhausted the marketability of the buzzword nano and have stepped it up to pico? Somehow I doubt that regular satellites mass 10^12 kilograms.
The engines on the the DNEPR-1 launched on 26 July 2006 shut down 86 seconds into the flight. It crashed approximately 25 km downrange. So, quite a bit of "bang" for your buck.
No folly is more costly than the folly of intolerant idealism. - Winston Churchill
Larger satellite use magnetorquers to orient themselves in orbit. To use magnetics as a drive system, your spacecraft would have to be long so you could pulse a magnetic field down the length of it (think of it as a rail gun in reverse).
Lozano's design relies on electrospraying, a physics process...
No way! I thought it would be a magic fairy magic process! (So magic, they used the word twice!) With glitter and unicorns!
</sarcasm>
Any sufficiently advanced intelligence is indistinguishable from stupidity.
Sounds like a variant of an ion drive, which have been around since the 50's.
You silly SCA types.
Just because you have a trebuchet that doesn't mean that anything that fits in the bucket is payload. -or maybe it does...
-I'm Just Sayin'
Cubesats are never the primary payload. They're individually tiny, so they're launched in bunches as a secondary payload along with something else much bigger. Their cubical shape makes for easy fabrication of both the satellite itself and the spring-loaded launcher that they're packed in for the launch. Since they're basically freeloading on some other launch, using empty space that would otherwise be completely wasted, their own form factor doesn't really matter much. They fit in the odd bits of leftover space that a typical satellite leaves inside a rocket faring.
And the usual answer to that is to unreel a tether after achieving orbit. In theory a picosatellite could contain a tether on a small spool. Admittedly getting such a thin tether to unwind properly might be difficult...
Each edge of a Rubik's cube is 5.7 cm long. The cubesats are 5.5 times as large.
Not anything that fits in the bucket is payload, but anything that IS in the bucket is payload... note to self: stay away from flingy end of trebuchets with SCA people in attendance.
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