NASA Sunjammer solar sail prepares to shoot the breeze
December 3, 2013
The team of NASA, L’Guarde, and Space Services Inc. are preparing for the Sunjammer space mission that in 2015 will see the first deep space deployment of a solar sail. On September 30, the Sunjammer team completed a milestone when they successfully deployed a quarter panel of the spacecraft’s solar sail.
The test was conducted at L’Guarde’s facility in Tustin California with the aim of demonstrating how the four sail quadrants would deploy from the spacecraft. For the ground-based test, only one quadrant of the 13,000 sq ft (1,200 sq m) sail was unfurled with a sturdy boom supporting the sail on two sides.
Carrying the test out under Earth gravity and with air resistance actually made things more difficult than an actual deployment in the weightlessness and vacuum of space. "If this test succeeded under these stressing conditions, we certainly anticipate it will work exceedingly well in space" says Nathan Barnes, President of L'Garde.
At launch, the sail will fold up into a package about the size of a dishwasher. Weighing about 70 lbs (32 kg), the sail is made of a fabric called Kapton, which is able to withstand the extreme temperatures of space.
The Sunjammer mission is scheduled to launch January, 2015, and will send the unique spacecraft out of the Earth’s orbit to a location near the Earth-Sun L1 Lagrangian point to study the Sun from closer quarters. It is hoped that the solar mission will bring further knowledge of the Sun, and help measure and understand solar storms. Besides the science mission, the spacecraft will carry a “cosmic archive” of recordings, music, and videos for future generations to discover.
Solar sails do not use rockets or propellants to maneuver in space but rely on sunlight bouncing off the reflective sail to produce thrust. Scientists first noticed that the tails of comets point away from the sun, indicating that some amount of force was being imparted by sunlight. The solar sail uses this principle that light exerts a tiny amount of pressure on a surface to change speed or direction in space.
The Sunjammer uses small triangular steering vanes at the corners of the sail to change the sail angle to the sunlight and thus its trajectory. While the amount of pressure created by sunlight is tiny, the sail is always in the light, and has an enormous surface area relative to its mass. The sunlight provided thrust builds up over time, giving potential for extensive voyages of exploration using the technology.
Commercial partners for the mission are L’Guarde, of Tustin California, and Space Services Inc, of Houston Texas. L’Guarde is a specialist in inflatable structures for space, and originally made inflatable targets and decoys for the Ballistic Missile Defense Organization. Space Services was once run by astronaut Donald “Deke” Slayton, and is most famous for providing space burial services via its subsidiary, Celestis.
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