Japan Successfully Deploys a Solar Sail in Space
EERE Network News - June 30, 2010
The Japan Aerospace Exploration Agency (JAXA) has successfully deployed
a solar sail in outer space. While solar energy has successfully powered
small cars and airplanes, nobody has yet managed to use the sun's energy
to propel a spacecraft, although that goal is now within reach of JAXA.
The agency's Small Solar Power Sail Demonstrator, or IKAROS
(Interplanetary Kite-craft Accelerated by Radiation of the Sun), was
launched on May 10 and passed its initial operation check on May 21. On
June 3, the agency began deploying the solar sail, and on June 10, JAXA
confirmed that the solar sail was successfully expanded.
The concept of a solar sail, which could use the pressure of sunlight to
propel a spacecraft, has long been a dream of both scientists and
science fiction writers. Though the concept is roughly 100 years old,
IKAROS will be the first practical demonstration of the technology. The
sail was deployed by spinning its cylindrical launch vehicle to 25
rotations per minute, then allowing angular momentum to spread the sail
out from that central hub to form a square measuring about 35 feet on
each side. The sail is made of an extremely thin, flexible plastic and
includes thin-film solar cells on part of its surface to generate
electricity. Over the next five months or so, JAXA will attempt to prove
the technology by accelerating the craft and steering it toward Venus.
Meanwhile, European engineers are aiming to set another first by flying
a piloted solar-powered airplane through one day and one night. The
Solar Impulse HB-SIA is scheduled to take off on the morning of July 1
on a flight that will continue until the morning of July 2. During the
day, the aircraft will charge its lithium-polymer batteries, then
increase the amount of available energy by climbing to an elevation of
nearly 28,000 feet. During the night, the craft will run on battery
power while slowly descending, greeting the morning at an elevation of
just under 5,000 feet. The Solar Impulse HB-SIA is essentially a flying
wing, with solar cells covering its entire 207-foot wingspan. The craft
is made from carbon fiber composites and is powered by four propellers,
each driven by a 7-kilowatt motor. The solar-powered aircraft is meant
to test the flight characteristics and performance of the technology in
preparation for a future craft that will be designed to fly around the
world on solar power.
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