Thursday, June 2, 2005
NASA has completed a major test of a 20-meter square solar sail, marking a “crucial milestone” in space propulsion technology. It is not the first to test solar sails, as the Japanese have deployed two solar sails in space. The Planetary Society is planning on launching a solar sail possibly by June 21.
Shot into orbit by a converted intercontinental ballistic missile (ICBM), the Cosmos 1 would be launched from a submerged Russian submarine from within the Barents Sea. The spacecraft, powered by the sail, will have no destination. The purpose is simply to test the propulsion system that uses the pressure from solar light particles to move the ship outward from a starting orbit around the earth at 500 miles.
The propulsion technology is currently believed to be the most efficient available for interstellar space travel. Theoretically a craft propelled by the pressure of a constant light source, such as a purpose-built laser, could achieve speeds approaching the speed of light. This is due to the efficiencies of the spacecraft not having to carry its own fuel. Approaching the speed of light would, however, require a long period of constant acceleration. Such high speed will be impossible for the current test vehicles and any launched in the foreseeable future, as they rely on the light from the Sun, which rapidly becomes weaker with increasing distance.
According to the National Geographic News, “NASA, the European Space Agency, Japan, and Russia all have developed solar sails, but none has yet tried to prove that the sails can propel a spacecraft under controlled flight.”