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From: al@ames.UUCP (Al Globus)
Newsgroups: net.space
Subject: Re: Momentum transfer in light sails
Message-ID: <841@ames.UUCP>
Date: Mon, 4-Mar-85 14:18:38 EST
Article-I.D.: ames.841
Posted: Mon Mar  4 14:18:38 1985
Date-Received: Sat, 9-Mar-85 10:50:15 EST
References: <794@mordor.UUCP>
Organization: NASA-Ames Research Center, Mtn. View, CA
Lines: 12

> 
> 
>      After reading Rick McGeers' description of momentum transfer between
> photons and a light sail, it seems to me that all momentum imparted to the
> sail must be radial to the sun.  Is there any way to impart momentum to the 
> sail in a tangential direction?

Yes.  The acceleration is normal to the plane of the sail.  Draw the
vectors in 2D in a piece of paper with the photon comming in at an
angle.  Take the vector sums and maintain conservation of momentum in
all directions and you'll see what I mean.   I wish I could put my
Mac drawings on this thing.