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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).
Something like a Magnetorquer?
No folly is more costly than the folly of intolerant idealism. - Winston Churchill
What about having Packing Ratio Sats that are designed to stuff as many sats as possible into the payload faring of a rocket? Are cubes the best for cylindrical rockets?
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'
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...
Engage the Ion Thrusters, No. 1.
Each edge of a Rubik's cube is 5.7 cm long. The cubesats are 5.5 times as large.
You know what's funny about this, is we're going to end up with a situation where increases in the propulsion systems end up sending newer satellites past ones launched earlier before they complete their missions. We'll end up with a cloud of ever decreasing technological junk arriving at distant civilizations....
Ace
I remember in physics class theorizing a propulsion system for a space ship. I figured that the only way to get thrust would be to accelerate hydrogen to as fast as you can then zip it out the thrusters. You'd have low mass, but high velocity propulsion. It sounds like this guy figured out a way to do this in a compact form. If this seriously works, I'm excited because it will allow satellites all over the solar system for relatively cheap. Put a high imaging camera on your satellite and snap pictures from around the solar system! It is nice that even though NASA has a shoestring budget that space exploration can still make advances.
God spoke to me.
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.
My blog. Good stuff (when I remember to update it). Read it.
Sorry, had to say it. That CubeSats? BORG CUBES!
Buanzo Consulting - 15 Years of GNU/Linux experience, for you.
Ion thrusters are used on just about every modern satellite needing trajectory correction, but this is one more small step for man. Analogy time - perpendicular recording technology on hard drives: It was not the jump from floppy disk to flash memory, but still a technological leap which made for an acceleration in increasing storage densities that had been stagnating for a while.
You fail to see this jump and potential - imagine a small array of these propulsion chips on both sides of the solar panel wings of normal sized satellites - they could be continuously spraying a few millinewtons of thrust when the attitude of the panels is near tangent to the orbit for the whole mission life to counteract orbital decay - with more efficient thrust per propellant weight than on-board ion thrusters, which could then be smaller or even eliminated if deemed redundant.
Now if we could figure out a way to install attitude control on parent poster...
DTUsat-I, a CubeSat attempted this a few years ago. Unfortunately contact was never established with the satellite so it has not actually been tested, but the physical construction is fairly simple.
More info.
I stopped reading after the 3rd or 4th time they explained what something as simple as an ion was. Hello MIT, you guys are eggheads, not the Discovery Channel.
I want to delete my account but Slashdot doesn't allow it.
A magnetotorquer applies torque, not thrust. It's a nice propellantless way to maintain orientation, though.
Stop worrying about the risks of nuclear power and start worrying about the risks of not using nuclear power.
How long can they last? Doesn't emitting ions cause the emitter to simply vaporize over time?