(Source: NerdModo)
The Sagan-inspired LightSail-1 will launch next year aboard a Russian or American rocket. (Source: Rick Sternbach/Planetary Society)
The solar sail will unfold once in orbit and hopefully catch the sun's light, helping it to acclerate. (Source: Frank O'Connell/The New York Times)
Design may be suitable for carrying probes to the stars
The problem of making space travel more efficient is a complex one. First there's the challenge of getting materials cheaply into orbit. Space elevators are currently viewed as perhaps the most promising solution for this. Then there's the challenge of developing sufficient impulse and thrust to push probes or spacecraft to the stars. For this challenge everything from plasma, to ion, to nuclear engines have been dreamed up.
Joining the various in-space alternative propulsion technologies to be tested in the near future is a relatively old idea -- the solar sail. Next year the Planetary Society, a space research group, and Cosmos Studios of Ithaca, N.Y., headed by Ann Druyan, a film producer and widow of the late astronomer and author Carl Sagan, will launch LightSail-1, a solar sail design.
Louis Friedman, Ph.D, director of the Planetary Society, brags, "Sailing on light is the only technology that can someday take us to the stars."
The solar sail was embraced by late writer Carl Sagan, and now is championed by his widow. The concept is simple -- absorb the energy from incoming light and cosmic rays and use it to accelerate the spacecraft, much like wind on an ocean sail. A solar sail's ability to constantly draw on solar energy for thrust enables it to, in theory, traverse the solar system in 5 years -- a feat likely not possible with other engine designs. With a concentrated laser, a 100 year trip to another solar system might be possible, allowing humans to potentially explore another solar system for the first time.
Currently radiation on such a trip would be prohibitive and would likely kill any humans that went solar sailing. Weight restrictions also would make such a long trip hard to manage -- the more weight you want to transport, the bigger the sail you need.
Both NASA and Japan's space agency, JAXA, have developed and tested solar sails, but thus far no one has tried to sail them anywhere. The collaboration between the Planetary Society and Cosmos Studios aims to be the first to do that, launching a series of solar sails over the next few years. It looks to first prove the technology, then launch a sail into deep space.
The group first tried to launch as solar sail called Cosmos-1 back in 2005. Approximately 100-feet per side, the square sail was launched from a Russian missile submarine in June 2005, but the launch failed, leaving the sail at the bottom of the Barents Sea.
Undeterred the team turned to a NASA contract for funding, developing a smaller 18-foot-per-side Nanosail, which could be used to deorbit satellites. They took that design and used it as a basis for the new LightSail-1.
The LightSail-1 features an aluminized Mylar sail, about a quarter as thick as a trash bag. The sail will carry three 4 in. x 4 in. x 4 in. CubeSats, tiny electronics boxes developed by students at Stanford. Two of the boxes hold the sails, before they are stretched, while the third will contain the electronics to control positioning of the sails. By positioning the sails to balance gravity with the force from solar energy, the spacecraft will be able to perform complex maneuvers like braking or hovering in place. The system will weigh a scant 5 kg to make the most of the small sail area.
The groups are looking to piggyback the design on an American or Russian rocket launch carrying another satellite. This should be possible thanks to the small size.
The first planned flight will simply send the sail into orbit and hopes to spot signs of acceleration via a built in camera. The team describes this as their "Kitty Hawk moment", referring to the famous Wright brothers flight. The next flight will involve a larger sail, which will orbit for several days building enough acceleration to raise its orbit tens or hundreds of miles.
A third flight will look to send a sail out of Earth's orbit, attempting to place it at the L1 point, about 900,000 miles from the Earth, where the solar gravity will be balanced by the force from light energy on the sail, causing the sail to stall in place, orbiting the sun. This most ambitious objective will likely require a small chemical rocket to provide the extra power needed to escape orbit, something that may frustrate fans of the design, admits Dr. Friedman.
However, Mr. Friedman likens the chemical rocket to the motor that is typically needed to get sailboats out of the harbor and onto the open sea. He says that once the Earth's gravity well is escaped, the sail can take over. If the team can achieve its goal, the positioned satellite will then be used to watch the sun's activity for magnetic storms that could damage spacecraft or on-Earth electronics.
"You can bet that Sony built a long-term business plan about being successful in Japan and that business plan is crumbling." -- Peter Moore, 24 hours before his Microsoft resignation
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