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From: karn@eagle.UUCP (Phil Karn)
Newsgroups: net.space
Subject: Re: Electric rockets
Message-ID: <1061@eagle.UUCP>
Date: Sun, 7-Aug-83 16:53:05 EDT
Article-I.D.: eagle.1061
Posted: Sun Aug  7 16:53:05 1983
Date-Received: Mon, 8-Aug-83 03:50:03 EDT
References: sri-arpa.3870
Lines: 19

Speaking of electric rockets, AMSAT has come up with a similar rocket that
could be used on a future payload launched from a GAS can on the
shuttle.  The problem here is that you want an engine to boost the
payload into a longer lived orbit than 300 km, but to prove to the NASA
people at the same time that it is intrinsically safe to fly on a manned
vehicle.

The proposal is to fly a steam rocket.  Liquid water is directly preheated
with solar energy and fed to a thrust chamber where an electrically
powered heater turns it to steam.  Specific impulse is terrible (~140 sec)
but mass isn't a limitation; only a couple tens of kilograms of water
would be required for the job.

Of course it would be much easier and quicker to just carry two solid
rocket motors to perform a two-impulse Hohmann transfer to the higher
circular orbit, but just getting permission from NASA to deploy
something from the GAS can will be a major accomplishment.

Phil