The World's Biggest Solar Sail Launches Next Year

Illustration for article titled The Worlds Biggest Solar Sail Launches Next Year

Space is noticeably short on gas 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.

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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 protonos 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 it's thinness and can withstand temperatures from −273 to +400 degrees C.

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Illustration for article titled The Worlds Biggest Solar Sail Launches Next Year

"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.

[Cleantechnica - Space - Wikipedia 1, 2 - NASA - Image: NASA]

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DISCUSSION

This is a solution to a rather specific problem though. It allows very long distance travel, but is rather useless for short distance. In order to begin travelling to, say, Mars or the asteroid belt, you need to get out of Earth's gravity well. This requires A LOT more thrust (and in a shorter time) than a solar sail can provide. A solar sail can be used to achieve great speeds at very little expense, but it takes a long time to get up to speed, and you have to be travelling away from the sun. This is pretty useless when you are stuck in Earth orbit.

Also, even if you have enough fuel for a traditional chemical engine to use to get an escape velocity, then all the work is already done, and your trajectory (if executed properly) will already be on an intercept with whatever object outside of Earth's SOI you are travelling to. No more energy is required (aside from minor course corrections).

Like I said, the solar sail is only really useful for travelling to places outside of the solar system (or at least to the outer solar system).