Japan's space sail generating energy

Japan's space sail was successfully deployed 770 kilometres above the earth and has started producing power, the country's main space agency said Friday.

The Japan Aerospace Exploration Agency said Ikaros — a 200-metre-square solar kite — was unfurled on Thursday and began using photons from the sun to produce energy.

"We have confirmed that it was successfully expanded and was generating power through its thin film solar cells," JAXA said in a press release. "We will measure and observe the power generation status of the thin film solar cells, accelerate the satellite by photon pressure, and verify the orbit control through that acceleration."

The Japanese experiment is designed to prove whether fabrics made from tiny solar cells can generate motion in space. Such a power source could assist in energy-generation in certain types of space missions.

The scientific theory underlying the technology is that photons — particles of light — hitting a highly reflective surface will exert pressure on the sail. Although the pressure is tiny, it is constant, scientists said, eventually resulting in movement.

A winner

JAXA is betting that the pressure will build up in sufficient quantities to be able to pull a small disk-shaped spacecraft which is already attached to the space kite.

Supporters, however, are already calling Japan's deployment of the sail a victory.

"They haven't demonstrated actual solar sailing yet — that's still to come, and may be weeks in the future — but with today's announcement they've achieved their stated minimum success goals for the mission, so it's definitely time to celebrate," said Emily Lakdawalla, writing on the website of The Planetary Society, an organization that advocates space exploration.