After nearly four years of delays, the world's first solar-sail-powered spacecraft is ready for its day in the sun.
Cosmos 1 will rocket into space June 21 aboard a modified Russian missile, according to mission planners.
If all is successful, the spacecraft will become the first to boost itself into a higher orbit using nothing more than the gentle pressure of sunlight bouncing off its sails. The feat could open the door to all sorts of new and far-reaching missions.
"Things are looking good for June 21st," said Louis Friedman, executive director of the Planetary Society, the nonprofit space advocacy group sponsoring the mission. "There's no threat to the mission at this point. We've done our best and we're proud of where we are."
Astronomers have long theorized that a spacecraft could propel itself through the cosmos cheaply by harnessing the pressure exerted by sunlight, the way sailboats use the pressure exerted by wind. Cosmos 1's sole mission is to test this technique.
Initially scheduled for a 2001 launch, the mission has been pushed back several times due to technical glitches, delays in getting parts and the need for additional ground tests, according to Friedman. An accident with a test flight in 2001 also set the mission back.
The keys to Cosmos 1's innovative propulsion system are its eight triangular sails, made from highly reflective, 50-foot-tall Mylar sheets. Mylar is the material commonly used for novelty helium-filled balloons.
Once the sails are unfurled in orbit at an altitude of about 500 miles, photons streaming away from the sun will bounce off them, giving the spacecraft a little push as they go.
Though these tiny pushes won't amount to much at first, they are expected to add up over time, propelling Cosmos 1 faster and faster. With each day that passes, the spacecraft is expected to gain another 100 mph in speed. Eventually, it will be able to fight Earth's gravitational pull and move into a higher orbit.
The demonstration will last no more than several weeks, according to the Planetary Society. By then, the spacecraft's fragile sails will have disintegrated.
In theory, however, a spacecraft with stronger sails could keep accelerating indefinitely, breaking out of Earth orbit and heading for other planets -- or even the edge of the solar system -- faster than any other spacecraft has gone before. In three years, a solar sail could be traveling faster than 100,000 mph. And it could do it without a drop of onboard fuel.
This is why both NASA and the Japanese Aerospace Exploration Agency are working on solar-sail projects of their own.
In 2004, the Japanese space agency unfurled two solar sails in space, but the prototypes tested only the deployment procedure, not the actual propulsion. NASA, meanwhile, is still testing its solar-sail technology in the lab.
Friedman said the Planetary Society team is proud to have beaten NASA in getting to the launch stage. But he acknowledged that the bigger and more expensive victories, like using a solar sail to travel to another planet, would most likely belong to NASA.
"In a positive way, we have sort of prodded them," said Friedman. "By committing to a test flight before them, we have put their eyes on the goal."
Kim Newton, a spokeswoman for NASA's Marshall Space Flight Center, said NASA has already asked the Planetary Society for data from the mission. "We're excited that they're doing it," she said. "Any developments are great."
The $4 million Cosmos 1 mission is funded largely by a donation from Cosmos Studios, a media and entertainment firm run by Ann Druyan, wife of the late astronomer Carl Sagan. Philanthropist Peter Lewis and members of the Planetary Society also donated to the cause, according to Friedman.
To save money, the Planetary Society will launch Cosmos 1 on a modified Russian ballistic missile, fired from a submarine in the Barents Sea. Friedman said the society got "a good deal" on the arrangement because Russia wants to find commercial uses for the missiles rather than destroying them.
The Planetary Society attempted to launch a prototype of Cosmos 1 in the same way in 2001, but the spacecraft failed to separate from the final stage of the missile. It crashed in Kamchatka, Russia.
