starship-design: solar sail

["Curtis L. Manges" <clmanges@worldnet.att.net>]

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.

First of all, since catenaries waste energy, I see the best sail design
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 payload
package at the hub. Fire your moon-based laser cannon, and away it goes.

Near arrival, the shape changes (requiring the services of the Mad
Topologist) to something more like a half-folded umbrella, with a middle
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.

Of course, this doesn't help you get back home again, but it might be
okay for a one-way robot explorer.

What think ye?

Curtis