NASA may have put an end to the shuttle program, but they continue to pursue cutting edge technology. The same people who took us to the moon and made memory foam a reality are now attempting to perfect and implement solar sails that could be used as an alternative energy source for deep space travel. Solar sails function much like regular sails on boats except that, instead of harnessing the power of wind, they harness sunlight. As Ray Sanders over at Universe Today explains it, photons from the sun are gathered by the sail and stored until there is enough power to provide thrust to a small spacecraft.
NASA has been experimenting with solar sail technology for a little while now. NanoSail-D, for example, has been slowly descending from the upper atmosphere via a solar sail and transmitting back data for months. The latest announced demonstration, however, would involve a solar sail 7 times larger than any flown in space to date. It will also test attitude control and execute a navigation sequence at mission-capable level, bringing us one step closer to implementation of the technology in actual space flight.
Successful solar sail technology would be a great boon to space travel. It would allow spacecraft to travel great distances on less fuel, potentially lowering the cost of missions if the sails are reliable and affordable enough. NASA says solar sails could be employed in a number of other areas, as well. Small solar sail thrusts could remove orbital debris and solar sails integrated into satellites could allow them to de-orbit at the end of their missions. Solar sails could also provide enough low thrust to stabilize space stations situated in otherwise unstable locations.