'Electric Sails' Could Propel Superfast Spacecraft by 2025

Robotic spacecraft may ride the solar wind toward interstellar space at unprecedented speeds a decade or so from now. Researchers are developing an "electric sail" (e-sail) propulsion system that would harness the solar wind, the stream of protons, electrons and other charged particles that flows outward from the sun at more than 1 million mph (1.6 million kilometers per hour). "It looks really, really promising for ultra-deep-space exploration," Les Johnson, of NASA's Marshall Space Flight Cent