A 64.5-foot-wide test version of the Sunjammer solar sail sits unfurled in a large vacuum chamber during tests at NASA’s Plum Brook facility in Ohio.
Slated for launch in 2017, the full-size 124-foot-wide version will be the largest orbiting solar sail ever, employing 13,000 square feet of thin Kapton film to harness the weak but constant force of solar photons. Movable vanes at the sail’s four corners act like rudders so operators can help it achieve and maintain a gravitationally stable solar orbit. Despite its size, the sail weighs just 70 pounds and will carry scientific instruments to observe space weather.
