Newsgroups: sci.space.shuttle
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: Shuttle computer reprogramming
Message-ID: <1988Oct11.194419.29631@utzoo.uucp>
Organization: U of Toronto Zoology
References: <6689@nsc.nsc.com> <6980@ihlpl.ATT.COM> <1938@kalliope.rice.edu> <1988Oct8.233609.11835@utzoo.uucp> <1347@thumper.bellcore.com>
Date: Tue, 11 Oct 88 19:44:19 GMT

In article <1347@thumper.bellcore.com> karn@thumper.bellcore.com (Phil R. Karn) writes:
>... In other words, the low
>cost of the mission and its non-life-and-death nature (no humans on
>board, remember?) make it feasible to carry out interesting and useful
>experiments that would otherwise be too risky...
>If a spacecraft computer crashes, you just boot it again on the next pass;
>it will keep itself safe until then.

In other words, it's risky but safe?  You couldn't trust it on a manned
spacecraft, but you do trust it to be rebootable?  Be consistent, please,
Phil -- either the thing can be trusted not to explode, or it can't.  If
the only consequence of a crash is denial of non-vital services, then the
low cost is the factor that matters, since it makes occasional temporary
loss of service acceptable, and the unmanned nature is irrelevant.  (For
example, non-space-hardened computers have flown on the shuttle, in non-
critical support roles.)

I take it that the Microsat hardware is not capable of doing anything
irrevocable, like switching its receivers off?
-- 
The meek can have the Earth;    |    Henry Spencer at U of Toronto Zoology
the rest of us have other plans.|uunet!attcan!utzoo!henry henry@zoo.toronto.edu