LightSail: Carl Sagan's solar sail spacecraft concept finally realised

A concept for a solar-powered space craft, first imagined 40 years ago by the late astronomer Carl Sagan, is to finally be realised in an ambitious project headed by "the Science Guy" Bill Nye.

The LightSail project, funded by the Planetary Society in the US, was first described publicly by Sagan on The Tonight Show in 1976.

"There's a tremendously exciting prospect called solar sailing, which travels on the radiation and particles that come out of the sun - the wind from the sun," Sagan told Johnny Carson.

"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."

Two variations of Sagan's solar sail have since been developed, one by NASA and one by the Japanese space agency IKAROS. The LightSail project marks the first privately-funded attempt.

The device itself consists of four triangular Mylar sails for navigation and a small "CubeSat" satellite that utilises four arms to deploy the sails. It also runs on the open-source Linux operating system and uses the C programming language to code its functions.

The Planetary Society, co-founded by Sagan and now led by Nye, now plans to test the LightSail device on 20 May in Earth orbit, with the hope of launching a space flight in 2016.

"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."