Newsgroups: sci.space
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: GEOS-6 dies.
Message-ID: <1989Feb9.013228.965@utzoo.uucp>
Organization: U of Toronto Zoology
References: <AXrTkzy00UkZI0RUwa@andrew.cmu.edu> <14215@cup.portal.com>
Date: Thu, 9 Feb 89 01:32:28 GMT

In article <14215@cup.portal.com> mmm@cup.portal.com (Mark Robert Thorson) writes:
>"But some satellites have suffered repeated problems with the light bulbs in
>an instrument the satellite uses to keep itself oriented."
>
>A light bulb?  I'm surprised.  That's like hearing a piece of string broke
>or a rubber band snapped.  Does anybody have more specific information on
>what this lightbulb was being used for?

As I recall, it's part of a sensor that encodes the position of rotating
parts in the satellite's scanner system.  Those bulbs are a notorious
reliability problem that is being designed out of more recent satellites;
even putting several of them in each encoder for redundancy hasn't brought
their reliability up to acceptable levels.
-- 
Allegedly heard aboard Mir: "A |     Henry Spencer at U of Toronto Zoology
toast to comrade Van Allen!!"  | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
