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Re: starship-design: solar sail

"Curtis L. Manges" <clmanges@worldnet.att.net> wrote:
> In discussions of solar/laser sail systems, the question of braking at
> destination seems to be a problem which hasn't been resolved. It has
> occurred to me that perhaps the sail can be physically reshaped to
> permit some braking, without having to turn the ship around.
Yeah, nanotech power!!!(or big machinery) 
> First of all, since catenaries waste energy, I see the best sail
> as a flat panel, for maximum rearward reflection of the beam. Think
of a
> bicycle wheel: a thin, light outer rim, with cables in place of rigid
> spokes, the reflecting material stretched across these, and the
> package at the hub. Fire your moon-based laser cannon, and away it
Why not a kite like shape??
> Near arrival, the shape changes (requiring the services of the Mad
> Topologist) to something more like a half-folded umbrella, with a
> concentric section of the sail being removed, and the inner and outer
> concentric sail sections forming a mirror system which sends the laser
> beam on ahead of you, hopefully providing some reverse pressure. Think
> of a simple periscope to envision the ray paths.
You can also use a second mirror in front of the big one. You'd have
to make a hole in the center of the principal reflector, but that'd be
easier than reshaping it...
So, when you want to brake, you do a hole in the middle of the
principal reflector, so that the laser beam passes though and reflects
to the main reflector...

> Of course, this doesn't help you get back home again, but it might be
> okay for a one-way robot explorer.
Well, the other planet's got a sun too... You could also build a laser
on the planet (or in orbit around the sun)

Vive le Québec libre... dé souverainistes!!!

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