Japan to Launch ‘Space Yacht’ Propelled by Solar Sail

IKAROS solar sail
An undated handout illustration shows the Interplanetary Kite-craft Accelerated by Radiation of the Sun (IKAROS) solar sail, provided to the media on April 27, 2010. Source: JAXA via Bloomberg

The Japan Aerospace Exploration Agency plans to launch the world’s first satellite powered by a giant solar sail to demonstrate next-generation renewable-energy technology, the agency said today.

The 20-meter (66-foot) sail, which cost about 1.5 billion yen ($16 million), will be wrapped around the “space yacht” during liftoff and will unfurl once the craft leaves the Earth’s atmosphere, JAXA said. The Ikaros will be launched by Mitsubishi Heavy Industries Ltd., Japan’s biggest heavy-machinery maker, from Tanegashima Space Center in southwestern Japan on May 18, the agency said.

The flexible sail is covered in a film of solar cells and will be about 32.5 micrometers thick, about half a human hair, JAXA said. The technology, known as thin-film solar, is being developed to one day replace fixed solar panels because it can be shaped to fit in small and irregularly shaped places, said Hiroaki Benten at Kyoto University.

“Solar film has an enormous potential for use in our everyday lives if this technology becomes economically viable,” Benten, an assistant professor of polymer chemistry, said today by telephone. “You’re going to be able to bring a solar-film battery with you as you walk about. It can be wrapped around anything.”

The sail propels the craft using resistance created by energy from the sun in much the same way as the wind propels a sailboat across the water. Photons, or solar energy particles, bounce off tiny mirrors, providing enough thrust for satellites to perform maneuvers such as rotating or hovering, JAXA said.

NASA, Russians

Solar sails can also use ion propulsion like conventional satellites. The panels generate electricity to ionize gas, which it emits at high speed to thrust the satellite, the U.S. National Aeronautics and Space Administration said on its Web site.

NASA and Russia are exploring solar-sail technology, which can create lighter and smaller craft than conventional satellites. While prototypes have been unfurled, no solar sail has been successfully used to propel a craft in space, JAXA said.

Thin-film solar cells are being developed by companies including First Solar Inc. and Toledo, Ohio-based Xunlight Corp. to expand the use of solar power beyond rooftop installations on houses and other buildings. The cells for Ikaros were supplied by Ames, Iowa-based PowerFilm Inc., JAXA said today.

Six-Month Mission

Ikaros’s mission will conclude within six months, and JAXA plans to launch a larger sail-powered satellite in the early part of the next decade to explore Jupiter and the Trojan asteroids, it said.

The Ikaros will use photon propulsion on this mission, and electricity from the sail will power equipment on the satellite. Both ion and photon propulsion will be used in the mission to Jupiter, according to JAXA.

Ikaros, a homonym for Icarus, the figure in Greek mythology who flew too close to the sun and fell to the sea, stands for Interplanetary Kite-craft Accelerated by Radiation of the Sun.

“Unlike the mythical Icarus, this Ikaros will not crash,” Yuichi Tsuda, an assistant professor at JAXA, said today.

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