Space is noticeably short on petrol stations, requiring spacecraft to carry huge reserves of expensive and cumbersome propellant which limits their range. But with NASA's newest Sun-powered propulsion concept, future astronauts could sail to the stars on solar winds.
Built by L'Garde Inc. of Tustin, California, the Sunjammer demonstrator is the largest solar sail ever constructed. It measures 124 x 124 feet when fully opened. That's about a third of an acre of surface area with which to catch the protons that constitute solar wind and generate the craft's 0.01 newton of thrust. For comparison, the Space Shuttle's pair of solid state rocket boosters generated a combined thrust of 5.3 million netwon.
Amazingly, the sail itself is a mere five microns thick. NASA collaborated with the DuPont company to fabricate the sheet out of Kapton, a flexible poyimide film often employed as the outermost layer of spacesuits. Kapton is surprisingly rugged despite its thinness and can withstand temperatures from −273 to +400 degrees C.
"All space travel right now is limited by expendables," said Billy Derbes, the chief engineer for Sunjammer. "If you show a technology not limited by expendables - and Kapton (the material the solar sail is constructed from) is a long-lasting film material - what new applications will people think up? We're opening up a whole new kind of thinking about how you do things in space."
NASA intends to launch the Sunjammer next year aboard SpaceX to conduct viability testing. NASA engineers will inspect the sail's altitude, navigation and trim controls, as well as its overall stability in flight. If the technology proves reliable, it could conceivably find use in the private sector as a propellantless propulsion system for asteroid-mining operations.