A spacecraft propelled through space by the radiation from the Sun was first envisioned by Carl Sagan 40 years ago. Next week it takes another step towards realisation when the LightSail project, funded by the Planetary Society in the US, launches it solar-powered sailing ship.
The ambitious project headed by “the Science Guy” Bill Nye, will test the craft on 20 May in Earth orbit – too low to capture the power of the Suns rays, but with the hope of launching a space flight in 2016.
“Light is made of packets of energy called photons. While photons have no mass, a photon traveling as a packet of light has energy and momentum.” the Planetary Society explains.
“Solar sail spacecraft capture light momentum with large, lightweight mirrored surfaces—sails. As light reflects off a sail, most of its momentum is transferred, pushing on the sail. The resulting acceleration is small, but continuous.”
Back in 1976, Sagan himself spoke of the power and advantages of the system in an appearance on Johnny Carson’s, The Tonight Show.
“It works exactly as an ordinary sail boat does, so it can go out from the sun, it can tack inwards to the sun, and because it has a constant acceleration it can get you around the inner part of the solar system a lot faster and a lot more conveniently than the usual sorts of rocket propulsion.”
LightSail is the third project to test the theory. One was previously developed by NASA and another by the Japanese space agency IKAROS.
The craft itself consists of four triangular Mylar sails for navigation and a small “CubeSat” satellite – about the size of a loaf of bread.
“I’m proud to say we’re about to realise Professor Sagan’s vision,” Nye said. “We have built our own light sail spacecraft – it’s our own solar sail.
“It’s remarkable. We’re advancing space science and exploration so the citizens of the world will be enabled to know the cosmos and our place within it.”
Bill Condie is a science journalist based in Adelaide, Australia.
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