From: Henry Spencer <henry@zoo.toronto.edu>
Newsgroups: sci.space.tech
Subject: Re: nuclear reactors in orbit
Date: Tue, 9 Jan 1996 17:50:24 GMT

In article <DKuzpq.Ant@cee.hw.ac.uk> ceeetc@cee.hw.ac.uk (Edward T Chappell) writes:
>some fiction authors suggest that big sypsats (russian /US ) are
>nuc powered but i dunno if this is true.

The Soviet military radar satellites were reactor-powered.  Those are the
only ones, aside from a few experimental reactors.  It is hard to keep
this kind of thing secret nowadays, because the sensitive detectors on
some of the astronomy satellites are affected by reactor radiation at
quite long distances.

An assortment of Earth-orbiting satellites used RTGs (which generate small
amounts of power from the heat of decaying isotopes), but that has gone
out of fashion for several reasons.

>Anyone know how nuclear batterys work ? i think they use plutonium
>but i cant figure out how they generate electricity

There were several different kinds of "nuclear batteries" in the 1950s.
For example, you could simply put two electrodes in a vacuum and coat one
with a beta-emitting isotope; the beta particles would charge the other
electrode negative, giving you a miniscule amount of current at very high
voltage.  RTGs are the only type of "nuclear battery" that worked well 
enough to be worth bothering with for actual applications.
-- 
Look, look, see Windows 95.  Buy, lemmings, buy!   |       Henry Spencer
Pay no attention to that cliff ahead...            |   henry@zoo.toronto.edu