Path: utzoo!linus!husc6!rutgers!bellcore!faline!thumper!karn
From: karn@thumper.bellcore.com (Phil R. Karn)
Newsgroups: sci.space.shuttle
Subject: Re: Payload of shuttle flight directly after last Challenger.
Summary: need for Pu in space
Keywords: Pu
Message-ID: <927@thumper.bellcore.com>
Date: 4 Feb 88 16:54:04 GMT
References: <347@flatline.UUCP> <1484@boulder.Colorado.EDU>
Organization: Bell Communications Research, Inc
Lines: 25

> As for Pu in space,  I've never understood how a satelite could use so much
> power that it would need a fision reactor insted of photovoltaic cells, and a
> battery?  Is there a weight problem?  Is it a political issue?

In addition to experimental applications, nuclear power is used in space
in the following situations:

1. Exploration of the outer solar system. Sunlight is too weak to illuminate
solar arrays adequately.  The waste heat from the radioactive decay of
plutonium is also used to keep the electronics warm.  (Pioneer,
Voyager, Galileo).

2. Exploration of the moon and planetary surfaces. Long periods of darkness
also make solar arrays nearly useless. (Apollo ALSEP, Viking. Surveyor and
Early ALSEP used solar arrays, but didn't through many lunar nights).

3. Extraordinarily large power requirements, such as the Soviet ocean
observation radars that have gotten all the publicity.

In my opinion, the safety issue has been greatly overblown. The plutonium
is relatively small and very well packaged. Hardly anybody noticed when the
Apollo 13 lunar module re-entered the earth's atmosphere and burned up,
depositing its plutonium on the bottom of the ocean.

Phil