Newsgroups: sci.space.shuttle,sci.space.policy
From: henry@spsystems.net (Henry Spencer)
Subject: COTS vs. space rating (was Re: X 38?)
Date: Mon, 3 Jan 2000 18:36:32 GMT

In article <386FF7A6.11C5A5EF@nospam.erols.com>,
rk  <stellare@nospam.erols.com> wrote:
>jon, tom does have a very valid point here.  if you look at the suppliers
>and their products, you will see, especially over this year, that many
>military suppliers have either dropped all military grade products or have
>made obsolete large numbers of them.  of course, many space-based products
>are either military product or military-derived product...

Alas, the hard cold fact is that building specialized parts with demanding
requirements costs a lot of money, and with a small (and shrinking) market
it's not a very attractive thing to do.  Those of us who need those parts
are going to have to either grit our teeth and pay a *bundle* for them
(even more than we're used to paying) to convince suppliers that they're
still worthwhile, or learn to do without.  I fear the latter is the way
the wind is blowing, and we'd better start figuring out how to cope...

>...the new specifications have provision
>for radiation-hardness in them, but a lot (and the ones i just pulled) have
>a '-' meaning you're on your own.  is radiation-hardness important?

I would claim that it's central, although not always important.  The space
environment really isn't that hard on electronic parts, given some care in
areas like thermal design.  The one way in which it is really different
and (potentially) demanding is radiation.  If the spec doesn't say
anything about radiation, you might as well just order from Digi-Key...

>oh, one last thing, if you try to use purely cots devices outside their
>intended environment, perhaps by "up-screening," you can get quite a bit of
>flak from the manufacturers as they get scared when their devices are used
>outside of their design/test limits.  the loudness of these companies is
>louder than just a mumble, too...

Not surprising; they're scared of being sued.  This is also why almost all
parts datasheets now carry warnings about how you're not allowed to use
the parts in "life support" equipment -- whose definition gets broader by
the month -- without getting permission from the supplier (fat chance).
The heart of the problem is that US law permits them to be sued if their
parts were in the box that failed, even if they had nothing to do with the
failure.  (There are major plastics companies which will no longer sell
*materials* to people who make heart pacemakers.)
--
The space program reminds me        |  Henry Spencer   henry@spsystems.net
of a government agency.  -Jim Baen  |      (aka henry@zoo.toronto.edu)