Solar Sailing

Russia Sails the Space Frontier

In 1993, the Russian Space Agency launched a 20-meter diameter, spinning mirror called Znamya 2 (pictured), hoping to beam solar power back to the ground.

"Some call Znamya 2 a sail because it was made of a large, lightweight reflector and unfurled like a solar sail might be unfurled," says Les Johnson of the NASA Marshall Space Flight Center, co-author of the newly published book Solar Sails: A Novel Approach to Interplanetary Travel. "In fact, if I were asked to demonstrate solar sail technology and was constrained to deploy it from a large spacecraft, I might design a 'sail' like Znamya."

The foil reflector unfurled and when illuminated produced a spot of light which crossed Europe from France to Russia. Unable to control its own flight, however, the mirror burned up in the atmosphere over Canada. Russia's proto-sail program was abandoned in 1999 after a larger, follow-up mission (Znamya 2.5) failed to deploy properly.

Solar sails were an accessory on India's INSAT 2A and 3A communications satellites, circa 1992 and 2003. The satellites were powered by a 4-panel solar array on one side. A solar sail was mounted on the north side of each satellite to offset the torque resulting from solar pressure on the array.

In 2004, the Japanese deployed solar sail materials sub-orbitally from a sounding rocket. Although it was not a demonstration of a free-flying solar sail that could be used for deep-space exploration, the deployment was nevertheless "a valuable milestone" remarks Friedman, who appreciates the challenges of deploying gossamer sheets from fast-moving spacecraft.

To date, no solar sail has been successfully deployed in space as a primary means of propulsion.

But solar sails have a bright future. Read on to find out more....