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From: Katz.uci-750a%Rand-Relay@sri-unix.UUCP
Newsgroups: net.space
Subject: Re: space elevators -- another advantage
Message-ID: <12844@sri-arpa.UUCP>
Date: Thu, 20-Oct-83 21:11:28 EDT
Article-I.D.: sri-arpa.12844
Posted: Thu Oct 20 21:11:28 1983
Date-Received: Wed, 26-Oct-83 01:29:29 EDT
Lines: 13

Although the chief advantage of rocket alternatives is that you don't have
to lift the fuel, energy recycling is another advantage.  With two way
transfers (i.e. missions which eventually return), some lifting methods can
act like an energy bank.  You make a withdrawal when going put (up in the
gravity well), and you return most of what you withdrew when you return.
For a space elevator and some other systems, payloads going down help to
supply energy for the payloads going up.  Admittedly, some energy is almost
always lost and one can't always store up enough between launches.

Thus, SSteinberg's summary of Newtonian mechanics of launch are correct, but
neglect the change in mass due to fuel burning.  You reminded him about the
mass change, but neglected energy recycling.  Is there anything else we left
out?