Solar sails use the steady stream of particles (and light) from the Sun (light sail when some other source is used, e.g. a laser) for propulsion, not unlike sailboats on Earth that utilize the force of wind to travel. Often cited as the future most economical way for inter-stellar travel, such sails would normally be large, thin, and lightweight, so as to capture the maximum possible radiation from the Sun. When the solar thrust is not needed, the sail can be either collapsed into a smaller area, or re-aligned to present the smallest area to the solar stream.
NASA engineers (and partners) are preparing to
test two 20-meter (66-feet) long solar sail propulsion system designs (starting April 18). Such sails can be utilized for deeps-space missions later in this century.
Solar Sail (Courtesy: Wikimedia)The system designs were developed by two engineering firms,
L'Garde Inc., of Tustin, and
ATK Space Systems of Goleta, both in California. Their work is led by the
In-Space Propulsion Technology Office at NASA's
Marshall Space Flight Center in Huntsville, Alabama.
Solar sails are normally hundreds of times thinner that a slice of paper. Thin, yet durable, the only hazards they might face in space is a random micro-meterorite impact. The NASA sails will be tested in a vacuum chamber that will simulate the space environment. Both the sails will be tested during April-June 2005.
Among the future propulsion systems that are currently on the drawing board, solar sails are the cheapest to implement, and have the greatest potential. Since there is little need for other fuel, solar-powered spaceships can be light-weight. And of course, by 2100, one should have such a hardy bunch of ships, carrying supplies from one space-colony to another in the solar system. Hey, it doesn't hurt to dream, right?! :):)