An anonymous donor has donated a million dollars to the Planetary Society to help get a solar sail up and running.
The organisation reckons it should have a spacecraft that can fly on sunlight alone by the end of next year.
The sail is literally pushed by photons. While they don't exactly give it much momentum to start with, they provide a continuous acceleration, allowing the sail to reach high speeds in a relatively short time.
This first model will remain in earth orbit at around 800km high. It will be built of a stack of three cubesats, each just ten centimeters across.
One will house the electronics, and the other two the four ultrathin Mylar sails. These sails together cover 32 square meters and are just 4.5 microns thick. They are arranged in a diamond shape, like a giant kite.
"Lightsail-1 fits into a volume of just three liters before the sails unfurl to fly on light. It's elegant," says Planetary Society Vice President Bill Nye.
If the first flight is successful, says the Planetary Society, LightSail-2 will be operated at higher orbit. "LightSail-3 will go to libration point L1, where we hope eventually to see a solar sail permanently placed as a solar weather station, monitoring geomagnetic storms," it says.
The solar sail will need a lift from a spacecraft that's headed that way anyway. "We have identified several candidate American and Russian launch possibilities and hope to make arrangements with a specific launch vehicle provider early in 2010," say the developers.