Artist’s conception of solar sail. (Credit: JAXA.)

Japan has successfully deployed a solar sail on a spacecraft, demonstrating for the first time that such technology can be used to convert the sun’s energy to the power needed to move a vessel in the cosmos. As an added feature, the IKAROS spacecraft uses LCD technology to alter its attitude using the pressure of sunlight – a first for solar sails.

The sail measures 20 meters diagonally, but is only 0.0075 millimeters thick – or about half the thickness of a human hair.

IKAROS launched in May, and soon after became the first solar sail to be propelled by sunlight. Liquid crystal devices along the outer edge of the sail are used to help steer the craft. These devices control the reflectivity of the outer sections of the sail; switching one on creates a mirror-like effect, allowing sunlight to push more on those parts. The sail can slowly be spun by turning the LCD devices on and off, synchronized to the spin cycle.

“With this we can control both the orbit and the attitude using only sunlight,” says Yuichi Tsuda of the Japan Aerospace Exploration Agency.

Compared with onboard thrusters, which remain the main method of steering spacecraft, the effect of the reflecting devices is slight. The sail can only change its attitude by about 1 degree per day, Tsuda says, and it gets less effective the faster the sail spins.

This short video displays images that IKAROS took of the solar sail from space. Try to ignore the Styx Muzak.

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