Posted on 12/03/2005 2:20:44 PM PST by KevinDavis
The Planetary Society solar sail team is working to try again to fly the world’s first solar sail spacecraft. With a tested spacecraft design, almost all flight components available, and at least two attractive launch vehicle possibilities, we are well positioned to reach our goal.
We’ve made considerable progress: Our Lavochkin/Space Research Institute team in Russia has identified two promising and affordable launch vehicles candidates for our spacecraft.
The Soyuz rocket with a Fregat upper stage successfully launched the European Space Agency’s Mars Express and Venus Express, among other missions. Soyuz is the reliable workhorse of Russian rockets and, with the Space Shuttle grounded, it is the only vehicle now taking astronauts to the International Space Station. It would carry our solar sail as secondary payload, piggybacking on a commercial launch.
(Excerpt) Read more at planetary.org ...
This has come up from time to time. I have asked the same question and have not had an answer. I can understand the part about "sailing" away from the sun. However, how do you get back?
Solar gravitational pull. Dive into the sun!
10. Can a solar sail only provide thrust away from the Sun?Basically, everything in the solar system is moving on its own momentum in a circumferential path around the sun. Angle the sails to take away some of that sideways momentum, and the sun's gravity will start to pull you in.
No, thrust can be generated inward or outward with respect to the sun. By turning the sail at different angles, we can add or subtract velocity to the spacecraft. When we add velocity, the sail flies away from the Sun. When we subtract velocity, its orbit spirals inward.
Russians have so far lost them two ships, but on their budget the Russians are probably all they can afford. The Russians aren't perfect, but they have gotten a lot up into orbit over the years and will likely succeed in time. At least along the way we've disposed of a couple old sub lunched ICBMs that they aren't pointed at us any longer and kept some of their scientists busy and off the terror WMD launching market. All for much less money than we waste on the average Democratic politician.
My thoughts exactly. Remember the last solar sail experiment that was launched on a refurbished Russian SLBM? And it ended up in Davey Jones' Locker?
Can the delta vee actually be directed? How much of the beam is reflected specularly?
Well the sail's made out of Mylar, which I guess has pretty good specular qualities.
Enough to overcome losses so that the resultant vector will point inward, toward the sun, or only enough to reduce the efficiency and slow the inevitable outward spiral a few percent?
Let me see if I have this straight. The solar sail spaceship is on a course away from the sun, being pushed by photons striking the sail. Of course, we know that it is not really going in a straight line away from the sun. It is really in a highly elliptical orbit around the sun. So we can lose the sail (furl) at any time and wait until the sun pulls it back along its highly elliptical orbit. Of course, that could take centuries. The idea seems to need some work.
Presumably until it reaches its target planet.
So we can lose the sail (furl) at any time and wait until the sun pulls it back along its highly elliptical orbit.
No, they don't furl the sail. Instead, they angle them off in a different direction. The light is going to push in a (more-or-less) perpendicular direction to the orientation of the sail. So the idea is to angle the sail so that the force of the light works mostly against the direction in which the craft is moving around the sun. This will allow the sun's gravity to work more effectively in pulling it back in.
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