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IKAROS spacecraft to unfurl solar sail, head to Venus

Japan is scheduled to launch the IKAROS spacecraft this week, which will be powered by wafer-thin solar sails. The craft is headed for Venus, making it the first to attempt interplanetary travel using only solar power.

By Correspondent / May 17, 2010


Japan will launch a spacecraft that will use a solar sail to attempt a trip to Venus and beyond later this week.

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The IKAROS spacecraft will be the first to attempt interplanetary travel using only solar power. It is among a package of satellites originally scheduled for launch in Japan on Tuesday but postponed until at least Friday due to thunder clouds. Also to be launched is a satellite named AKATSUKI designed to orbit Venus and study its climate.

But it is IKAROS (an acronym from "Interplanetary Kite-Craft Accelerated by Radiation Of the Sun") that is grabbing the attention of the global scientific community with its hybrid solar sail technology, not least because its relatively low $16 million price tag carries the prospect of a boom for space exploration.

After it separates from the launch rocket, centrifugal force will open IKAROS' wafer-thin sail, which Japan's JAXA space agency expects will propel the craft to Venus.

The craft will use energy from the sun in two different way. Photonic radiation will bounce off the 14 meter (46 foot) solar sail, pushing the craft forwards like a yacht sailing into the wind. In addition, thin-film solar panels on the 0.0075 millimeter thick sail should power an ion-propulsion engine, making IKAROS a hybrid spacecraft.

The idea of solar sails has been around for almost a century and the European Space Agency, Russia and the US have all tried to master the technology.

“One of the main differences between IKAROS and the two solar-powered craft the US launched previously is that they were earth-orbiting satellites. Whereas this is the first time interplanetary travel has been attempted with solar technology,” explains Yuichi Tsuda, one of the scientists working on the project. “And the two US missions failed.”

Six-month trip to Venus

IKAROS is expected to take six months to reach Venus, and the team is hoping it will go on communicating for up to a year as it goes past the planet and continues its journey.

“Solar sailing has been the 'ace in the hole' of space travel. And now the technology seems to have been developed very well by this project,” says Kazuto Suzuki, an expert on space policy who has previously worked for JAXA and as a government adviser on the subject.

The IKAROS, which weighs 675 pounds, cost about a tenth of a conventional spacecraft, according to the project’s Dr. Tsuda.