bic_fuel_000822 LOGAN, Utah Using the same butane fuel found in cigarette lighters, the smallest
propulsion system to fly in space will help a soccer ball-sized "nanosatellite" rendezvous with another spacecraft late this year.After considering various thruster propellants, designers chose butane, so "in the end, we flew a Bic lighter in space, " said Jeffrey Ward, managing director of Britains Surrey Satellite Technology, Ltd. "It shows you can build small propulsion systems that are cheap and can work."
Building the 1-pound (450-gram) thruster system for $15,000 with off-the-shelf parts "brings us one step closer to swarms of nanosatellites performing cooperative missions" while flying in formation, he added.
Butane is not ignited by the newfangled thruster, but instead vaporizes "like gas coming out of a spray can," Ward said. The propulsion system is aboard the 14-pound (6.5-kilogram) SNAP 1 satellite, which was launched June 28 on a COSMOS rocket that blasted off from Russias Plesetsk Cosmodrome. The rocket also carried the 110-pound (50-kilogram) Tsinghua 1 microsatellite and a much larger search-and-rescue satellite that is part of a joint U.S.-Russian system to detect beacons from downed aircraft and ships in trouble, Ward said.
This 1-pound, butane-powered thruster is used to maneuver the SNAP 1 nanosatellite.
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thruster was tested for the first time for 100 milliseconds on August 15, then for three seconds on August 16, when it raised SNAP 1s orbit by 164 feet (50 meters), he said.Ward said the thruster will fire 30 more times during the coming weeks so SNAP 1 can rendezvous in November with Tsinghua 1, a microsatellite developed by Surrey and by Chinas
Tsinghua Aerospace Research Center.The entire propulsion system carries a mere 1.15 ounces (32.6 grams) of butane, Ward said.
He called SNAP 1 "the smallest propulsive satellite thats ever been flown" and the thruster "the smaller propulsion system ever flown."
Triangular-shaped tank
One of the propulsion systems unusual features is that its fuel "tank" is not tank-shaped, but instead is made of $25 worth of triangular-shaped coils of titanium alloy tubing.
Ward spoke Monday as Utah State University and the American Institute of Aeronautics and Astronautics opened the 14th annual Small Satellite Conference in Logan, Utah. The meeting, which runs through Thursday, drew nearly 500 people from universities, space agencies, space contractors and the military.
The new propulsion system "is innovative," said Robert Meurer, the meetings technical chairman and a senior director of Orbital Sciences Corp. in Dulles, Virginia. "When we start to truly get into building constellations of nanosatellites, it will take these kinds of innovative, somewhat outside-the-box ideas to make it work."
SNAP 1 the Surrey Nanosatellite Applications Platform satellite "is about the size of a soccer ball" and was designed, built and launched in only seven months, said Ward, whose company is a commercial-satellite-building arm of the University of Surrey.
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The tiny satellite was designed to demonstrate how nanosatellites can be used to rendezvous with and inspect other satellites, and to test technologies for rendezvous and for swarms of nanosatellites to fly in formation, he added.
SNAP 1 is supposed to take pictures of Tsinghua 1. Ward said the idea is to use cameras on nanosatellites to inspect other satellites to confirm deployments of solar panels, instruments and antennas; identify the causes of malfunctions; or simply for surveillance purposes.
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propulsion system will raise SNAP 1s orbit so Tsinghua 1 can catch up with it. Then SNAP 1 is to move within 330 feet (100 meters) of the other satellite. 
"In the end, we flew a Bic lighter in space."
But the technology is so new that "if we get anywhere near it, it will be a big success," Ward said.
Because SNAP 1 had to be built quickly and cheaply, the propulsion fuel had to be loaded in Surrey before the satellite was shipped to Russia for launch.
The safety of butane
Hydrazine and ammonia were considered too toxic, although ammonia might be used in future systems, Ward said. Nitrogen or xenon gas could not be used because high pressure was required to store enough of those gases, and the off-the-shelf thruster parts could handle only low pressures.
That left propane or butane as possible thruster propellants because the required amounts could be carried on a tiny satellite at low pressures, Ward said. Butane was chosen for its safety.
Butane is a decidedly low-tech way to power nanosatellite thrusters. Ward said engineers believe that in the future, the ideal thrusters for tiny satellites will either be powered by
ion propulsion, by microthrusters, which are like integrated circuits with tiny explosives, or by micro-electromechanical systems (MEMS) which are extremely tiny, fuel-containing thrusters.
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