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Shiny and crinkly, the material looks more like something meant to wrap frozen foods than to provide a new way to travel through space. The aluminized Mylar reflects sunlight, thereby deriving a little kick from the recoiling photons. In principle, big sheets could act as solar sails that over time would reach speeds exceeding 100 kilometers a second—far faster than chemical rockets. The first solar sail, called Cosmos 1, will go for its test flight in early 2004. The demonstration of a revolutionary way to travel to the planets and maybe even to the stars would seem to be a...

Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured , along with a brief explanation written by a professional astronomer. 2003 March 8 Solar Sail Credit: NASA / MSFC Illustration Explanation: Nearly 400 years ago astronomer Johannes Kepler observed comet tails blown by a solar breeze and suggested that vessels might likewise navigate through space using appropriately fashioned sails. It is now widely recognized that sunlight does indeed produce a force which moves comet tails and a large, reflective sail could be a practical means of propelling...

<p>A long-time goal of space enthusiasts is about to reach fruition — the first solar sail is about to take flight.</p> <p>It's great to see it finally happening.</p> <p>To the degree that many people are aware of the concept of solar sails, they mistakenly believe — taking the nautical analogy — that they are blown by the solar wind. But solar sails, or light sails (the more generic term, because they could be powered with lasers as well as the sun) actually get their thrust from radiation pressure. The solar wind is composed of heavy, highly-energetic particles that would blow right through a sail, destroying rather than propelling it. The sail is instead impinged by photons, the components of light.</p>