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Path: utzoo!henry
From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.space
Subject: re: launch windows
Message-ID: <5300@utzoo.UUCP>
Date: Tue, 19-Mar-85 13:50:35 EST
Article-I.D.: utzoo.5300
Posted: Tue Mar 19 13:50:35 1985
Date-Received: Tue, 19-Mar-85 13:50:35 EST
References: <1091@mordor.UUCP>, <310@petrus.UUCP>
Organization: U of Toronto Zoology
Lines: 12

As Phil mentions, it is generally more efficient to do plane changes
at apogee.  I thought people might be interested in why.  Basically,
when you're far away from a gravitating body, all orbits look similar
in one sense:  velocities are small, and the differences between the
velocity vectors of different orbits are therefore small.  So you can
make orbit changes in general, and plane changes in particular, with
relatively modest expenditures of fuel.  Of course, you have to haul
the fuel up to the maneuvering altitude, but it turns out that you
still come out ahead in general.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry