Solar sail

Heard on NPR this morning that The Planetary Society is about ready to test their solar sail. It will launch tomorrow out of a Russian submarine in a converted ICBM.

Launch Time: June 21, 2005 19:46:09 UTC (GMT)

There are solar sail-like representations that you may have seen in 'Tron' (the Solar Sailer) and 'Star Wars: Attack of the Clones' (Count Dooku's ship).

Do you know that solar sails are pushed by photons? This test model will 'have a total surface area of 600 square meters (6500 square feet). This is about one and a half times the size of a basketball court.' Solar sails, in concept (since this is the first trial), accelerate VERY slowly, as you might imagine. 'a solar sail on an interplanetary mission would gain only 1 millimeter per second in speed every second.' But solar sails accelerate CONSTANTLY, carry no fuel, and:

can ultimately reach speeds much greater than those of a rocket-launched craft. At an acceleration rate of 1 millimeter per second per second (20 times  greater than the expected acceleration for Cosmos 1), a solar sail would increase its speed by approximately 310 kilometers per hour (195 mph) after one day, moving 7500 kilometers (4700 miles) in the process. After 12 days it will have increased its speed 3700 kilometers per hour (2300 mph)... Given time, however, with small but constant acceleration, a solar sail spacecraft can reach any desired [non-relativistic] speed.

Where does the coolness stop?!