Believers in extraterrestrial life cheered today as the Japanese space agency, JAXA, successfully unfurled a solar sail in space for the first time. Solar sails offer the best hope for deep space exploration because they eliminate the need to carry fuel. Deploying them is no easy task — given, you know, the whole lack of gravity thing — but this morning’s action went off without a hitch.
The Japanese spacecraft IKAROS created centrifugal force by spinning, allowing it to launch the .0003-inch-thick sail. While deployment is a challenge in a zero gravity environment, spacecraft — unlike airplanes — don’t have to contend with drag, so with each photon of light that hits the sail, the spacecraft could gather speed. The sail isn’t yet propelling IKAROS; that will be the true measure of the mission’s success.