Solar spacecraft launch cleared to go

PASADENA, Calif. Monday's announcement comes more than four years after the society's first solar sail spacecraft ended up in the ocean when the Russian rocket carrying it failed to reach orbit. The new project is being boosted by an anonymous $1 million donation.

The Planetary Society hopes to launch three solar sail spacecraft over the next few years, the first by the end of next year.

A solar sail is not propelled by the stream of ionized gas known as the solar wind but by the pressure of light, photons pushing against a surface.

AP contributed to this report.