Giving CubeSats Electric Propulsion 74
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 a revolution (Score:5, Insightful)
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 [umich.edu]
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.
Re:CubeSats are a revolution (Score:4, Insightful)
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.
Yeah... Just what we need -- more tiny objects in orbit around Earth. We have enough problems avoiding crashing into the big satellites we can actually see with radar, let alone worrying about a few hundred rubic's cubes up there. -_- Big satellites can be retired from choice orbits and sent to a maintenance orbit, or back plunging into the atmosphere to burn up. Is this tech going to provide enough thrust to de-orbit when they die?
Re:CubeSats are a revolution (Score:5, Funny)
Yeah... Just what we need -- more tiny objects in orbit around Earth. We have enough problems avoiding crashing into the big satellites we can actually see with radar, let alone worrying about a few hundred rubic's cubes up there.
That was my first thought, too. My second thought, after reading TFA, was that this guy has slightly modified the basic design of an inkjet printer and figured out a way to avoid having his business cut into by refill vendors.
Re:CubeSats are a revolution (Score:4, Funny)
That was my first thought, too. My second thought, after reading TFA, was that this guy has slightly modified the basic design of an inkjet printer and figured out a way to avoid having his business cut into by refill vendors.
At $6,000+ a gallon, we should consider using rocket fuel in our inkjet printers instead. It'd be cheaper...
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My 1st thought was "Damn. I've been hearing about $10,000 to put up 1kg for almost 15 years now; when is it finally going to get here"?
My 2nd thought was that I'm not going to update my plans for a primarily Solar Powered, electrostatic ion thruster propelled, Black Sabbath "Sabotage" playing mars probe.
It would take about 15 years to get there.
Re:CubeSats are a revolution (Score:5, Informative)
This is where electrodynamic tethers [wikipedia.org] and laser brooms [wikipedia.org] come in handy.
PACKING RATIO (Score:2)
Re:PACKING RATIO (Score:5, Interesting)
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.
Re:CubeSats are a revolution (Score:5, Informative)
Well, despite what the article says, most CubeSats are launched into deteriorating orbits which eventually burn up.
As for radar, yes, it's nice to be able to get ground confirmation and CubeSats are more than big enough to do that, especially considering they are deployed on-orbit in clusters.
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I think it is actually the FCC that dictates that a satellite must decay in 25 years after the completion of the mission. This all comes about because they license LEO.
Re:CubeSats are a revolution (Score:5, Informative)
The Air Force and other government agencies are interested in using CubeSats that can move between different orbits in space, and more specifically, that have the propulsion required to reenter Earth’s atmosphere and destroy themselves at the end of their mission (thereby keeping them from becoming “space junk”).
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The article also says they don't need it because they'd be placed in a destructive orbit anyway. So which is it? Probably both. There's nothing about the design that requires it to be in a certain orbit. Some may be placed in LEO. Others in polar orbit... others, maybe into a non-destructive orbit.
Where's the backup if the primary propulsion system fails? Oh. Right... there isn't one. One loose wire and it'll be up there for centuries, instead of years.
Re:CubeSats are a revolution (Score:4, Insightful)
Having propulsion means you can operate it for a long time in an orbit which will decay and still expect it to reenter if it stops working.
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Space Craft [feeddistiller.com] Feed @ Feed Distiller [feeddistiller.com]
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Re:CubeSats are a revolution (Score:4, Informative)
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Pico (Score:5, Funny)
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.
Re:Pico (Score:4, Funny)
Marketing bullshit is currently up to femto.
See femtocell.
Re:Pico (Score:5, Funny)
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...it makes sense, no?
Yoda? Is that you? I told you to go back to bed again! It only makes sense to you, because you’re senile! ;)
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Uh, Yoda would have said "Sense it makes, no?"
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Actually, it's a typo.
Typosats? I guess you're talking about the Mars Climate Orbiter [wikipedia.org] ;)
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Having recently attended a small satellite conference, I learned that when it comes to satellites, micro- refers to satellites under 100 kg, nano- refers to satellites under 10 kg, and pico- refers to satellites under 1 kg. Since the nominal mass of a 1-unit CubeSat is 1 kg, they are typically called picosatellites.
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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.
Small to the eXtreme!!!
Re:Pico (Score:4, Insightful)
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.
Small to the eXtreme!!!
The mass of the moon is 7.36 × 1022 kilograms [google.com] so maybe 10^12 is normal for natural satellites.
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Launched, yes. Orbited, not so much. (Score:5, Informative)
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This should be part of the intro - none of these satellites currently exist. They were all blown up during their failed launch.
Re:Launched, yes. Orbited, not so much. (Score:4, Informative)
This should be part of the intro - none of these satellites currently exist. They were all blown up during their failed launch.
Actually that's incorrect. My predecessors had a cubesat on the DNEPR-1 launch; yes it blew up. That said, it was neither the first rocket to carry cubesats, nor by any means the last. TFA is correct in saying there are at least a dozen of these satellites in orbit right now, although many are now past their operation a life, and are waiting to naturally burn up. Saying that "none of these exist" is a bit of a misnomer as well, since there are cubesats waiting for launch in labs all around the world; I myself have two that will likely be going up in about three years from now.
TFA is correct, however, in saying that no cubesat currently has a propulsion system. It is wrong, however, in saying that no one else is working on this problem; in fact that is the very topic of my own research. I'd be much more impressed, however, if we could see simulations of the corrected orbits, estimated increases in lifetime, and, best yet, a working prototype. Claiming you can do this is bold; it is not an easy problem. Chemical rockets, and even 'standard' electric propulsion are become well-characterized solutions. Cubesat propulsion is on a completely different level, based on both the weakness of the thrusters, and the relatively low masses of the satellites. I feel this is a bit premature to be posted on the front of slashdot; this should have gone up in the 4-5 months TFA claims it will take to get a working prototype. That said, I applaud the novel approach. I hope it works, 'cause I know I'd buy one.
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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'
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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.
Re:why even use propelant ? (Score:4, Interesting)
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).
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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...
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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 [dtusat.dtu.dk].
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A magnetotorquer applies torque, not thrust. It's a nice propellantless way to maintain orientation, though.
A physics process? (Score:4, Insightful)
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>
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Personally, I was expecting that every CubeSat would have its own pony. OMG! PONIES! LOTS AND LOTS OF PINK PONIES!!!11!!!!
Ion drive (Score:3, Interesting)
Sounds like a variant of an ion drive [wikipedia.org], which have been around since the 50's.
Re:Ion drive (Score:4, Insightful)
A variant, yes, but without the high energy cost of ionizing the fuel during thrusting. Also not much need for accelerating structures. if the article is accurate, the reaction mass is pre-ionized and locked into the structure. When you need thrust you pretty much just release it and it pushes you away. Neat trick, if the article is accurate.
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This doesn't sound like vaporware or pseudo-science -- I'd imagine the article is pretty accurate.
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I wonder how they manage that? Isn't it equivalent to carrying a very large electric charge and somehow keeping it from getting neutralized? Same problem as in large capacitors. If they have tech to do that, wouldn't it be a wonderful electricity storage system!
engage (Score:1)
Engage the Ion [memory-alpha.org] Thrusters [wikipedia.org], No. 1.
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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
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How long can they last? Doesn't emitting ions cause the emitter to simply vaporize over time?
Too large for a Rubik's cube (Score:3, Informative)
Each edge of a Rubik's cube is 5.7 cm long. The cubesats are 5.5 times as large.
As the technology increases (Score:2)
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....
Cool, sounds like it holds water (Score:2)
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If it's in LEO, there should be enough free atmospheric molecules (and hydrogen) to run an EHD-based "lifter" type of propulsion (aka Biefeld-Brown or Serrano effect), given an electrical supply (solar cells?):
http://en.wikipedia.org/wiki/Ionocraft [wikipedia.org]
So, no need to store fuel, either.
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One problem I see coming up is energy, roughly speaking (Newtonian physics) kinetic energy is proportional to the square of the velocity
So if you double your exhaust velocity (and keep your energy losses the same) you double your propellant efficiency but halve your energy efficiency.
In other words if you want a spaceship with high acceleration and high propellant efficancy you are going to need to find a shitload of power from somewhere....
BORG! (Score:1)
MIT = written for retards? (Score:1)
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.