Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/5/84; site mordor.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!ihnp4!zehntel!dual!mordor!space@mit-mc From: space@mit-mc Newsgroups: net.space Subject: Re: Momentum transfer in light sails Message-ID: <788@mordor.UUCP> Date: Fri, 1-Mar-85 17:33:32 EST Article-I.D.: mordor.788 Posted: Fri Mar 1 17:33:32 1985 Date-Received: Sun, 3-Mar-85 03:09:36 EST Sender: daemon@mordor.UUCP Lines: 21 From: Rick McGeer (on an aaa-60-s)Sure there is. Use various sails, of differing sizes, at varying angles and distances from your craft. The momentum vector of your craft is the sum of the momentum vectors of the various light sails, which are all radial to the sun (but the sum vector need not be). The restriction is that net momentum is always *away* from the sun: you can't accelerate in a sunward direction using a light sail. Actually, now that I think of it, there's no reason that the momentum vector of a sail need be radial to the sun: if the sail were forced to deform, so that pole of the sail was not in its centre, then the resultant vector *wouldn't* be radial to the sun. Further thought on tacking into the sun: yes, it can be done, if you use gravitational interactions. That is, tack in an outbound direction against your current elliptical solar orbit: you'll kill your radial velocity and fall inward. Rick.