Artist's impression of a solar sail. Photo: Michael Carroll/The Planetary Society.

The Planetary Society announced Wednesday that it plans to continue a project to fly a solar sail despite the failure of a suborbital test flight last month.

Officials of the space advocacy organization and its partners said that they will attempt an orbital test flight of the Cosmos 1 solar sail early next year. The announcement was made at the Planetary Society headquarters in Pasadena, California.

"The next flight in the Cosmos 1 solar sail project will be an orbital test of an eight-bladed sail," said Louis Friedman, executive director of the Planetary Society.

The status of the project was uncertain after the failure of a suborbital test flight July 20. That flight was going to test the deployment mechanism for the solar sail using two "blades", or segments, of the full eight-blade sail. However, the spacecraft failed to separate from the third stage of the Volna booster that launched it.

An investigation into the launch failure traced the problem to the booster's third-stage engine, which failed to generate as much thrust as planned. Software on the rocket then failed to issue the command for the spacecraft to separate, dooming the mission.

"This error had nothing to do with the payload or solar sail spacecraft, but was a rare problem in our rocket," said Viacheslav Danyelkin, deputy director of the Makeev Rocket Design Bureau, the Russian organization responsible for the launch vehicle.

Rather than refly the suborbital test, however, the Planetary Society and its Russian partners decided to go ahead with the orbital flight of the full solar sail. "The experience gained preparing and integrating the payload was valuable enough to allow us to proceed to the next step," said Konstantin Pichkhadze, general director of the Babakin Space Center, designers of Cosmos 1.

"We are more committed than ever to the mission, and we can't wait to share it with the world," said Ann Druyan, CEO of Cosmos Studios, one of the sponsors of the mission. Druyan is also the widow of famed astronomer Carl Sagan, one of the founders of the Planetary Society.

If all goes well, the Cosmos 1 solar sail will be launched in early 2002 by another Volna booster, launched from a submarine in the Barents Sea. Once launched, the 40-kilogram spacecraft will deploy eight triangular blades, forming a sail 30 meters in diameter. The spacecraft will use this sail to gradually spiral out from its initial 850-kilometer Earth orbit.

The Planetary Society also said that it will also begin work building a backup to Cosmos 1, funded by insurance money collected after the July launch failure. That spacecraft would be used for another flight later in 2002 if Cosmos 1 fails to meet its mission objectives.

If successful, the flight would be the first ever for a solar sail. The concept of the solar sail -- using reflected light to slowly but continuously propel a spacecraft -- is not new: the idea dates back to the 1920s, and has been studied in detail by NASA and other space agencies for decades. A 1970s NASA proposal to use a solar sail on the mission to Halley's Comet was rejected and a 1980s international competition to build solar sails for a race to the Moon fizzled out by the early 1990s because of a lack of funding.

The mission will also mark other firsts. The mission will be the first mission organized and funded by a space interest organization, and is also the first privately-funded mission to test space exploration technology. The cost of the mission is estimated to be several mission dollars.