Making the stuff of science fiction into reality, NASA engineers are testing solar sails–a unique propulsion technology that one day could enable deep space missions. Much like the wind pushing a sailboat through water, solar sails rely on sunlight to propel vehicles through space. The sail captures constantly streaming solar particles, called photons, with giant sails built from a lightweight material. Over time, the buildup of these particles provides enough thrust for a small spacecraft to travel in space. This image is of a four-quadrant solar sail system, measuring 66 feet on each side that is being tested in the world’s largest vacuum chamber at NASA’s Glenn Research Center at Plum Brook Station in Sandusky, Ohio. Image Credit: NASA