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From: pearse@hound.UUCP (S.PEARSE)
Newsgroups: net.space
Subject: Re: Gravity slingshots
Message-ID: <1153@hound.UUCP>
Date: Tue, 14-May-85 10:55:33 EDT
Article-I.D.: hound.1153
Posted: Tue May 14 10:55:33 1985
Date-Received: Wed, 15-May-85 01:15:34 EDT
References: <1671@mordor.UUCP> <24@escher.UUCP>, <10563@brl-tgr.ARPA> <5592@utzoo.UUCP>, <1169@phoenix.UUCP>
Organization: AT&T Bell Labs, Holmdel NJ
Lines: 11

I have read a lot of sci-fi books which use the principle of "Gravity
Slingshots". Could someone explain from a net-energy point of view
how this works? I know you don't get something for nothing. When
a satellite approaches Jupiter, it gains energy from the approach,
but as it departs, it loses just as much. Where is the net gain
in velocity=energy? Is it from Jupiter's orbital velocity?

Thanks,
-- 
Steve Pearse
ihnp4!hound!pearse