A new approach to solar sails is taking shape in a clean room in an Illinois laboratory. Researchers there have designed a sail that would unfurl from bobbins into a giant space ribbon 250 meters long, says Victoria Coverstone, an aerospace engineer at the University of Illinois at Urbana-Champaign. This project, also dubbed Cube Sail, is basically ready to fly, she says, if the team can find money for a launch and to upgrade the Mylar film that makes up the sail. The Illinois group next aims to test a spinning deployment of sail blades, on the way to an ambitiously large spinning sail whose rotating blades could measure up to 5 or even 10 kilometers long.
Meanwhile, the German space agency DLR and the European Space Agency are planning their own series of solar sails dubbed Gossamer. The first of these would launch a 25-square-meter sail into Earth orbit in 2014, followed by bigger ones over the next several years.
Japan and U.S. have been working on solar sails and the privately funded Planetary Society expects to launch its own sail in 2012, as does a satellite design team based at the University of Surrey in England. After 100 days, a solar sail could reach 14,000 kilometers per hour; after three years it could be zipping along at 240,000 kilometers per hour. At that rate it could get to Pluto in less than five years, rather than the nine years the plutonium-powered New Horizons spacecraft, now on its way, is taking. Solar sails are the tortoise to the hare of chemical rocketry.
In 2010, IKAROS unfolded its sail, 20 meters across diagonally, and made its way toward Venus, flying past that planet in December. By turning on and off an innovative set of liquid crystals, project engineers showed they could change the sail’s reflectivity and thus direct its motion.
JAXA has extended the mission to March 2012 so engineers can test some more risky flight maneuvers. “I’m just so in admiration of them,” says Friedman. The agency is also working on a much larger solar sail, 50 meters across, with hopes of launching it around 2020 to set sail for Jupiter and distant asteroids. Eventually, JAXA wants to develop novel hybrid propulsion systems, combining solar sails with ion drives to enable long trips through the solar system.