A typical solar sail picks up just one millimeter in speed per second of
acceleration. But the advantage it has over a conventional rocket is that
acceleration is constant and can be maintained over a period of days, weeks, or
months. While a rocket stops accelerating after a few minutes of firing, a
solar sail just keeps on going. At an acceleration rate of 1 millimeter per
second per second, a typical solar sail would increase its speed by
approximately 195 miles per hour after one day, moving 4700 miles in the
process. After 12 days it will have increased its speed to 2300 miles per hour.
A solar sailed probe would reach Pluto in five years, rather than the nine
years for the rocket propelled probe now being readied by NASA. A space craft
propelled by a solar sail does not encumber itself with fuel that a space craft
propelled by a rocket must take with it.
History of the Solar Sail
Solar sails were first proposed by the German astronomer Johannes Kepler in
the 17th Century. The concept was rediscovered by Friedrich Zander in the
1920s. In the 1970s, the Jet Propulsion Laboratory investigated several solar
sail concepts for a possible probe to Halley’s Comet. The Japanese managed to
launch two prototype solar sails on August
9th, 2004. The latest attempted test of a solar sail was conducted
by the Planetary Society and was called Cosmos 1.
Cosmos 1
The Planetary Society, in conjunction with Cosmos Studios, attempted to
launch a prototype of a solar sail called Cosmos 1. Cosmos 1 would have used a
solar sail changed as eight triangular blades that could be rotated to maneuver
the space craft. It was to be launched into low Earth by a Russian submarine
using a Volna rocket. It would have deployed the sails and spent several weeks
maneuvering in low Earth orbit using just the light pressure of the sun to
propel the sail. Unfortunately, the launch attempt which took place on June
21st of 2005 ended in failure with the Cosmos 1 never deploying.