[img2=left]
http://i.a.cnn.net/cnn/2005/TECH/space/06/21/russia.cosmos.reut/story.spacesail2.jpg[/img2]The world's first solar sail spacecraft takes flight on Tuesday, launched by space enthusiasts who cobbled the privately funded mission together on $4 million and an untested theory that light can power limitless space exploration.
Cosmos 1, a disc-shaped craft whose two segmented sails suggest flower petals, is set to blast off from a submerged Russian submarine in the Barents Sea at 12:46 p.m. PDT (1946 GMT) on Tuesday.
Mission controllers hope to fill each sail's four 49-foot (15-meter) segments with streams of photons, or light particles, emanating from the sun to lift Cosmos 1 to a higher orbit.
The mission's sponsors at the Planetary Society in Pasadena, California, think Cosmos 1's flight ultimately will prove the science-fiction conceit that sailing to the stars aboard a light-powered ship is possible.
"Our role is as the dreamers and instigators behind this spacecraft," Emily Lakdawalla, project operations assistant, said on Monday.
"It is very promising technology but one that nobody is really pursuing into space. All we are trying to do is to demonstrate that the technology can work," Lakdawalla said.
The project started as a dream held by Planetary Society founders Carl Sagan, the late science fiction writer, and Louis Friedman, who proposed sending a solar sail craft to rendezvous with Halley's Comet in the 1970s when he worked at NASA.
Friedman, the society's executive director, and others believed the impact from a constant stream of photons bouncing off a huge sail be enough would impel a craft through frictionless space at an ever-increasing rate of speed.
With sunlight as its only fuel, a solar sail craft could open the farthest reaches of the solar system to space travel.
Off drawing board
The collapse of the Soviet Union and the need to find commercial uses for Russia's long-range missiles helped Cosmos 1 get off the drawing board three decades later.
The project was funded mainly by an entertainment company run by Sagan's widow, Ann Druyan, and by contributions from Planetary Society members and philanthropist Peter Lewis.
Cosmos 1 was built by Russian spacecraft contractor NPO Lavochkin. It will be launched in the tip of a converted intercontinental ballistic missile that was part of the Soviet Cold War arsenal. The plan is for it to orbit Earth for at least a month.
The rocket trip and a boost from a "kick motor" will put the 220.5-pound (100 kg) spacecraft into orbit about 550 miles (885 km) above Earth shortly after 1 p.m. PDT (1800 GMT).
Cosmos 1 will orbit for several days to acclimatize its instruments to the vacuum of space before its twin sails are deployed via inflatable booms. Mission controls now plan to deploy the sails late on Saturday.
Each sail is made up of eight triangular blades whose combined structure looks like a disk. The reflective Mylar sails are about 5 microns thick, or about one-quarter the thickness of a plastic trash bag.
After it deploys its sails, Cosmos 1 will be visible as it circles the Earth about once every 100 minutes.
