Newsgroups: sci.space.shuttle
From: henry@spsystems.net (Henry Spencer)
Subject: Re: New Shuttle
Date: Tue, 1 Jun 1999 14:36:31 GMT

In article <7ivu7q$87m$1@helix.cs.uoregon.edu>,
Christopher Michael Jones <cjones@ix.cs.uoregon.edu> wrote:
>> First, the shuttle, as a government-funded government-run launch system,
>> simply won't be replaced.  That was a stupid approach, and it won't be
>> done again.  If nothing else, there is just no chance that Congress would
>> fund it, not with NASA's recent record on big projects.
>
>Although, the shuttle is no-longer government-run, since the United
>Space Alliance manages it.

No, U.S.A. manages it *for NASA*.  NASA still makes all major decisions,
plans the missions, and supplies the crews.  The troops now wear U.S.A.
badges instead of NASA badges, but the marching orders still come from
JSC.  Recently, the head of U.S.A. was (essentially) fired for proposing
that this might eventually change.

>> ...The orbiters theoretically are good for 100 flights
>> each, but whether they will last that long in reality is uncertain.
>
>Also, it should be noted that the idea of a fixed "lifetime" is not
>very useful.  In addition to the extensive refurbishment every
>shuttle undergoes between flights, there are routine major shuttle
>modifications.  Considering that it would essentially take something
>like the airfram "breaking" to fully retire a shuttle, it seems as
>though they have a near infinite lifetime.

No, eventually the major airframe components will start showing fatigue
problems.  That's the usual life-limiting factor for an aircraft, and it
is the ultimate limit on orbiter life too, since the production line is
closed and no replacement parts are available.

Just when that will happen is unclear.  Precise prediction of fatigue life
is black magic rather than routine engineering, and nasty surprises during
operational service are not uncommon.  This is a particularly sticky
problem for the orbiters, since the extensive thermal insulation (both the
tiles etc. on the outside, and internal insulation in many areas) makes it
very difficult to inspect the structure regularly, as would normally be
done for an aircraft.
--
The good old days                   |  Henry Spencer   henry@spsystems.net
weren't.                            |      (aka henry@zoo.toronto.edu)