The difficulty is that rockets need so much fuel that they can't push their own weight into interstellar space. Thin, reflective sails could be propelled through space by sunlight, microwave beams or laser beams - just as the wind pushes sailboats on Earth. Rays of light from the Sun would provide tremendous momentum to the gigantic structure. The sail will be the largest spacecraft ever built, spanning 440 yards - twice the diameter of the Louisiana Superdome. Nothing this big has ever been deployed in space.
Researchers are optimistic about recent breakthroughs with strong, lightweight composite materials.
In space the material would unfurl like a fan when it's deployed from an expendable rocket. The Marshall Center is leading NASA's transportation research for interstellar probes. Engineers at Marshall are conducting laboratory experiments to evaluate and characterize materials for space sails. Materials will be exposed to harsh conditions in a simulated space environment to test their performance and durability in extremely hot and cold temperatures. The emphasis of the current research effort is on the interstellar precursor missions designed to set the stage for missions to other star systems later this century.