Newsgroups: sci.space.shuttle
From: henry@spsystems.net (Henry Spencer)
Subject: lifetimes (was Re: The joys of automated docking systems)
Date: Sun, 19 Nov 2000 19:32:06 GMT

In article <yDRR5.274$hm.9864@grover.nit.gwu.edu>,
Dwayne Allen Day  <wayneday@gwis2.circ.gwu.edu> wrote:
>: Also note that the standard design life for most GEO commsats is 15
>: years.
>
>I think that's high.  I believe that the standard design life is about ten
>years, with 15 being the ultimate goal lifetime.

Modern comsat designs, e.g. the HS 702, are designed and specced for 15
years -- that's a commitment, not just an ultimate goal, and yes, that
means that *everything* is supposed to be still working after 15 years.
(The power output of the solar arrays will inevitably have degraded some,
but that is figured into their original size, so that the satellite can
still operate at full power.)

The design life of comsats has been steadily creeping upward as experience
builds up and reliability improves.  It's now routine for them to run out
of stationkeeping fuel while otherwise still nearly 100% functional, and
that has been driving increased lifetimes:  despite occasional nonsense
about "they're obsolete after ten years anyway", in fact every added month
of useful lifetime is worth quite a bit of money, although often in a
secondary role or for a second owner.
--
When failure is not an option, success  |  Henry Spencer   henry@spsystems.net
can get expensive.   -- Peter Stibrany  |      (aka henry@zoo.toronto.edu)