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[Chicago Astronomer - Astro Joe]

Solar Sail Plans from NASA

NASA

Solar sails are a creative and unique way to harness the sun's energy for transportation, requiring no other fuel. Solar sails act just as the name implies: They are a physical sail, pushed by the sun's energy. The sun constantly spews out a high-energy stream of photons. (Photons create the images "caught" by camera film, digital camera CCDs, and the rods and cones in our eyes. "Photograph" and "photon"... It's not a coincidence. In fact, a solar sail is sometimes called a "photon sail". But for this article, the literal - and perhaps more appropriate - name loses out to the conceptual one: Photon sails are out, and we'll stick with "solar sails".

The sun shines, spraying photons in all directions. The solar sail is just a large panel, highly reflective and very lightweight. The force of the photons pushes the against the solar sail. The sail is attached to a spaceship (the green pickle-like thing above), and the force of the photons moves it away from the sun. The direction of movement can be changed by changing the angle of the solar sail. There's not much to it, apart from mind-melting high-level mathematics needed to steer the thing, designing an ultra-light yet strong frame, and knowing how to manage the gigantic sail itself. A fairly simple concept, but executing it requires heavy brainpower.

Here is some background info on the effoerts from NASA and their Solar Sail projects.

From Andybrain.com:

www.andybrain.com/extras/solar-sail.htm#sail1

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It's a shame that The Planetary Societies Solar Sail failed. I anticipate the next ones.

[Maddad]

I was surprised to discover that a solar sail can not only propell a space craft to another star, but it can also slow it down at the end of the voyage as well. I don't remember all of the web page, but something on the craft detaches. That part reflects light back to the space craft, giving it a photon push in the opposite direction, thereby braking it.

[Chicago Astronomer - Astro Joe]

To continue on this thought...

I haven't studied the mechanics of the Solar Sail theory, but it would seem to me that there is a point between two stars that equals out - where the pushing and the pulling forces of the suns balance. Is it that the momentum of the initial push carries the craft into the gravitational field of the target star?
Hmmmmm... #dunno#

The braking concept is also interesting as well...

[Maddad]

Yeah, I would expect that the craft builds up a high speed initially, like in the first year, when it is close to the first star. Then it would mostly just coast to the target star. Only problem is, what do you do when you need to go to the bathroom in the middle?