Solar Sail Launch Date Set

smooth wombat writes "Get out your PDAs and set aside March 1, 2005. That is date the solar sail, named Cosmos 1, is set to be launched from a submerged Russian submarine in the Barents Sea. If the sail cannot be launched on that date the launch window extends to April 7. The goal of the mission is to be the first controlled solar-sail flight. The project is being undertaken by The Planetary Society, which was co-founded by Carl Sagan. Space.com also has a writeup about the launch. The announcement of the launch date coincided with Carl Sagan's birthday. Sagan would have been 70 years old. He served as President of The Planetary Society until his death in 1996."

Comments

How controlled is controlled

[delta_avi_delta]

Do they simply plan to test the technology in a straightforward drag-test away from the sun, or is it "truely" controlled - will they send it away from earth and then bring it back?

Re:How controlled is controlled

[Councilor Hart]

How can they brink it back?
The sail catches the particles emitted by the sun, and is driven forward by them.
Inside the solar system, the direction of these particles is outward. Their speed/impuls is larger than that of extra solar system particles coming in.
Anyway, the net effect is a wind blowing out of the solar system.
No way to bring it back in the same way it got there.

Can anyone tell me what's up with /. these days? I have been gone for 3 months, and now it's damn slow and infested with 503's.

Re:How controlled is controlled

[delta_avi_delta]

Well, if you take the "wind" metaphor, and the "sail" metaphor, I was wondering if someone had figured a way to metaphorically "tack"

Re:How controlled is controlled

[pragma_x]

But even a sailboat cannot sail directly /into/ the wind.

It might be able to to sail (indirectly) towards the sun, if it uses gravity to tack. This is akin to how a sailboat tacks by using its keel as an opposing force to the wind. Also, positioning the sails perpendicular to the solar wind will also allow it to use a local gravity well (Earth, Venus, Saturn, etc) more effectively.

Re:How controlled is controlled

[Retric]

The thing is orbiting the sun at a high rate of speed. All they need to do is angle sail such that it's acceleration reduces the sail's orbital speed and it will enter a lower orbit.

It would take a while but the best way to get a solar sail out of the sun's gravity well is to give it a vary eliptical orbit and then acsellerate as fast as it can on the last pass by the sun.

Re:How controlled is controlled

[merlin_jim]

In order to tack, you need to be able to hold a sail at 45 degrees to the wind, while holding your vessel pointing towards the wind, with a predisposition to move in that direction (supplied by the hull/daggerboard) which, while feasibly possible with a solar sail, would be an engineering feat, to say the very least.

not feasibly possible the way you describe it. There is no hull, there's no viscuous medium. Sailboats tack by transferring momentum to the water through the keel or whatever.

Solar sails can't do that. If we could build a solar sail that could do that, we could build a warp drive, because what you're talking about is a reactionless thruster.

Now what we CAN do is in fact even easier. Through out the sailboat metaphor. You've got a flat sheet with a significant amount of radiation pressure on it, with a central mass with quite a bit of orbital inertia.

You *can* tack against that orbital inertia, using the radiation pressure to keep the sail taut. Change the lengths of the cables connecting the sail to the inertial mass and you can change the direction that the radiation pressure is thrusting you in, up to about 45 degrees away from out in either direction.

See my other post in this story for a discussion of how to use that thrust to move closer to the sun.

Re:Acceleration

[Tsalg]

Forget about solar wind - have a laser shooting at it. Some plans involve banks of lasers or microwave transmitters in orbit around the Earth or the Sun or even on the lunar surface to accelerate the craft, rather than using solar photons. With that you could reach 1/10th of the speed of light (about 300,000 km/sec), though there are other, rather more optimistic, suggestions that as much as half the speed of light could be obtained.

One of the major problems with these designs are the lasers would have to be prohibitively large to prevent the beams diverging at great distances. Further to this laser technology would have to be greatly improved to hit moving targets millions of kilometres away.

more about that on solar sails webpage