U.S. Department of Energy

    Planetary Society Launches a Solar Sail

    June 22, 2005


    An illustration of the solar sail, consisting of eight triangles connected by one corner to a central white dot and forming a loose octagon, although the triangles are tilted slightly out of the plane of the octagon. In the background is space, with part of the Earth showing in one corner of the illustration.

    An artist's conception of the solar sail in orbit.
    Credit: The Planetary Society

    The Planetary Society launched a prototype "solar sail" into space on June 21st, marking the first attempt to prove that thin films of reflective material can be deployed in space to capture the solar wind. Solar sails may one day serve as a space propulsion technology; although they accelerate slowly, they will continue to accelerate for a long time without the need for fuel. The Planetary Society, which bills itself as the world's largest nonprofit, non-governmental space advocacy group, is trying to prove the potential of solar sails by placing one in Earth orbit. Called Cosmos 1, the craft features eight triangular sails, each 50 feet long, which will deploy outward from the small craft. Cosmos 1 was launched from a Russian nuclear submarine aboard a converted intercontinental ballistic missile. As of the evening of June 21st, the Planetary Society still didn't know if the craft was successfully inserted into Earth orbit and operating correctly. If the launch proves successful, Cosmos 1 will attempt to capture the solar wind and use the energy to move to a higher orbit. See the Solar Sail Web site, and for the latest news, see the Solar Sail Weblog, posted by the Planetary Society's Emily Lakdawalla.

    Both Japan and the United States are investigating solar sails. Japan's Institute of Space and Astronautical Science (ISAS) successfully deployed two solar sails in space last August, but did not attempt to control the sails once they were launched. Last month, Alliant Techsystems and the National Aeronautic and Space Administration (NASA) conducted a successful ground test of a solar sail measuring 66 feet wide in a vacuum chamber operated by the NASA Glenn Research Center. See the press releases from ISAS and Alliant Techsystems.