Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/18/84; site uwvax.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!allegra!bellcore!decvax!genrad!mit-eddie!godot!harvard!seismo!uwvax!derek
From: derek@uwvax.UUCP (Derek Zahn)
Newsgroups: net.space
Subject: Re: Light Sails
Message-ID: <129@uwvax.UUCP>
Date: Thu, 21-Feb-85 18:12:38 EST
Article-I.D.: uwvax.129
Posted: Thu Feb 21 18:12:38 1985
Date-Received: Tue, 26-Feb-85 20:32:28 EST
References: <595@mordor.UUCP>
Organization: U of Wisconsin CS Dept
Lines: 27

I is only an ameteur, so bear with me.

I am under the impression that a Light Sail would get its propulsion from
the solar wind, a stream of protons and neutrons that are expelled from
the sun constantly (and cause the Aurora Borealis, I think).  It seems to
me that the "light pressure" from photons would be insufficient for any
substantial thrust.

What we need to know (from some more knowledgable source), is the velocity
and density of the solar wind.  If someone could post this and similar 
information, I would appreciate it, since I have been thinking about it
lately.  Anyway, from this, it should not be too hard to compute what
velocity could be attained by a light sail if we make some assumptions about
area/mass of the sail material.

I think that when launching a light sail, we would want to launch it directly
toward the sun.  The reason for this is that closer to the sun the solar wind
should be denser and we can get more thrust there -- in fact, I suspect that
most of our acceleration will be gotten quite close to the sun.

Any comments?

derek
-- 
Derek Zahn @ wisconsin
...!{allegra,heurikon,ihnp4,seismo,sfwin,ucbvax,uwm-evax}!uwvax!derek
derek@wisc-rsch.arpa