Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/18/84; site petrus.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!allegra!bellcore!petrus!karn
From: karn@petrus.UUCP
Newsgroups: net.space,net.physics
Subject: Re:  Re: Light Sails
Message-ID: <302@petrus.UUCP>
Date: Mon, 4-Mar-85 10:18:11 EST
Article-I.D.: petrus.302
Posted: Mon Mar  4 10:18:11 1985
Date-Received: Tue, 5-Mar-85 02:43:08 EST
References: <861@mordor.UUCP> <6960@rochester.UUCP>
Organization: Bell Communications Research, Inc
Lines: 8
Xref: watmath net.space:3664 net.physics:2201

It would seem to me that photons reflected off a sail would indeed appear
to be shifted in wavelength to an observer watching both the outgoing solar
radiation and the reflected radiation. This would be due to the doppler
shift caused by the relative motion of the sail with respect to the sun.
The effect is equivalent to that which makes a police radar function.
Energy is still conserved.

Phil