Today's launch of the first spacecraft powered by a hybrid solar sail was scrubbed due to bad weather. The Japan Aerospace Exploration Agency will try again on May 21. In the meantime, National Geographic News has a feature about the solar sail technology, something of a holy grail in space exploration since the idea was first proposed nearly a century ago. The spacecraft, called Ikaros (Interplanetary Kite-Craft Accelerated by Radiation of the Sun), is outfitted with a 14-meter-wide sail that will hopefully get it to Venus and beyond. From National Geographic:
"It's the space equivalent of a yacht sailing on the sea," said Yuichi Tsuda, deputy project manager for Ikaros. Like wind filling a boat's sails, particles of light–or photons–streaming from the sun bounce onto a mirrorlike aluminized solar sail.
As each photon strikes, its momentum is transmitted to the spacecraft, which begins to gather speed in the almost frictionless environment of space. A solar sail can eventually reach speeds five to ten times greater than a rocket powered by conventional fuels.
Ikaros is considered a hybrid, because the sail's membrane–itself just 0.0075 millimeters thick–sports thin-film solar cells for generating electricity, which will power Ikaros's high-efficiency ion-propulsion engines, Tsuda said.
The first month of the Ikaros mission will be spent deploying the sail and carrying out initial checks, Tsuda said.
"As soon as the sail has deployed, the craft will be able to start solar sailing," Tsuda said. "Over the six-month scheduled duration of the mission, we believe it will reach a velocity of a hundred meters [328 feet] per second."