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From: maxwell@babel.DEC
Newsgroups: net.space
Subject: Light-weight, omni-directional communications...
Message-ID: <2373@decwrl.UUCP>
Date: Thu, 30-May-85 10:17:02 EDT
Article-I.D.: decwrl.2373
Posted: Thu May 30 10:17:02 1985
Date-Received: Sat, 1-Jun-85 01:34:41 EDT
Sender: daemon@decwrl.UUCP
Organization: DEC Engineering Network
Lines: 16

Regarding Henry Spencer's ultra-light (2 kg) sail payload:

> Power and  communications  will obviously be major issues.... Communications
> will probably require a steerable antenna, alas. Would optical communication
> be better?

If an  omni-directional  mirror,  such  as those left on the moon as a laser
target,  could  be  made  light  enough,  how about the following: Cover the
'mirror'  with  an  LCD  shutter, which is modulated by (low power) on-board
electronics.  The payload is tracked by ground based telescopes, which point
a laser  at  the  target  (the  sail  should be easy to track optically) and
record  the  reflection. Result: no moving parts. Problems to solve: mass of
mirror,  LCD  longevity,  and the mirror's size, shape and fight orientation
(since it's fixed relative to the sail throughout the flight).

-+- Sid Maxwell, DEC @ Spit Brook, Nahsua NH