Developers of a secondary NASA payload on the next SpaceX Falcon 1 launch attempt hope to demonstrate deployment of a solar sail in orbit, advancing a concept that holds promise in both deep-space propulsion and debris mitigation in low-Earth orbit.

Dubbed NanoSail-D, the aluminum and plastic payload weighs less than 10 pounds, and unfurls to a four-segment square about 10 feet on a side on four spokes that roll out from a central hub.

It is designed to ride in a piggyback-payload "Poly Picosatellite Orbital Deployer" developed by the University of California Polytechnic Institute, and open up in a 685-by-330 kilometer orbit at an inclination of 9 degrees to demonstrate solar-wind propulsion.

Engineers see large solar sails as an efficient way for spacecraft to harness the "wind" of particles blown from the sun and achieve high-velocities as they move into deep space.

From its initial orbit NanoSail-D is set to use drag from the tenuous atmosphere at that altitude to slow it back to a reentry five to 14 days after launch, according to Edward Montgomery of NASA's Marshall Space Flight Center, the payload manager.

"NanoSail-D will be the first fully deployed solar sail in space, and the first spacecraft to use solar pressure as a primary means of attitude control or orbital maneuvering," Montgomery says.

Launch from the SpaceX facility at Kwajalein Atoll's Omelek Island is set for a window that opens July 29 and runs until Aug. 6. On June 25 SpaceX conducted a launch-pad static test of the rocket, which will be making its third attempt to reach orbit.

Photo of NanoSail-D during ground preparations: NASA