Setting Sail Into Space, Propelled by Sunshine

Peter Pan would be so happy.

About a year from now, if all goes well, a box about the size of a loaf of bread will pop out of a rocket some 500 miles above the Earth. There in the vacuum it will unfurl four triangular sails as shiny as moonlight and only barely more substantial. Then it will slowly rise on a sunbeam and move across the stars.

LightSail-1, as it is dubbed, will not make it to Neverland. At best the device will sail a few hours and gain a few miles in altitude. But those hours will mark a milestone for a dream that is almost as old as the rocket age itself, and as romantic: to navigate the cosmos on winds of starlight the way sailors for thousands of years have navigated the ocean on the winds of the Earth.

“Sailing on light is the only technology that can someday take us to the stars,” said Louis Friedman, director of the Planetary Society, the worldwide organization of space enthusiasts.

Even as the National Aeronautics and Space Administration continues to flounder in a search for its future, Dr. Friedman announced Monday that the Planetary Society, with help from an anonymous donor, would be taking baby steps toward a future worthy of science fiction. Over the next three years, the society will build and fly a series of solar-sail spacecraft dubbed LightSails, first in orbit around the Earth and eventually into deeper space.

http://www.nytimes.com/2009/11/10/science/space/10solar.html?th&emc=th

"There is also a misunderstanding that solar sails capture energy primarily from the solar wind high speed charged particles emitted from the sun. These particles would impart a small amount of momentum upon striking the sail, but this effect would be small compared to the force due to radiation pressure from light reflected from the sail. The force due to light pressure is about 5,000 times as strong as that due to solar wind. A much larger type of sail called a magsail would employ the solar wind.<24>.<25>"

http://en.wikipedia.org/wiki/Solar_sail