Randall Clague wrote:

On Fri, 06 Jun 2003 19:50:17 +0100, Ian Woollard
<[EMAIL PROTECTED]> wrote:

Yes, but how quickly the equipment ages is all part of launch experience too. When I say launch a/ lot/, I mean, wear out the vehicle in 4 months ;-)

You don't want to wear it out that fast.  If you do, you're running
too close to your margins, and you're going to fail something in
flight.

Provided the cargo isn't valuable, it matters a little less if you lose the vehicle towards the end of its life. And if it does fail early, you fix up the margins one way or another so it doesn't happen again.

 (Hugh Cook has a good line last week: the objective of
verification is to ensure that the parts count does not change during
flight.)

;-)

Does depend on how you verify the payload release mechanism/ejection seat though.

Whilst complacency played a small part with the Shuttle mishaps, I would argue that the root cause of the two major accidents were design faults.


There's enough fault to go around with both Shuttle mishaps.

There always is in these sorts of cases though; every failure has to make it through half a dozen layers to actually cause a big problem.

 Given
that they chose to live with the design decisions their forbears made,
they needed to be REALLY persnickety on the safety issues.

Yes, but Challenger didn't have to do that; they can and did do a redesign, that one was very clearcut. I'm not 100% sure whether Columbia is quite so clear yet. The foam is a very strange problem; problems like popcorning are not obviously soluble, but I'll bet they won't have the raft sections anymore at the very least. But the tile damage on every flight is, with ok, a certain amount of hindsight, a clear sign that the design is screwed up, and IRC it was mentioned like that even in the Challenger report.

DC-X; well that was done on an absolute shoe-string, I don't think you can draw any huge conclusions.


No, but maybe a small one.  The guy that failed to connect the landing
gear line, and the guy that checked his work?  I have to wonder how
they were doing on crew rest that day.  I'm thinking not so good.

Me, I'm thinking that the crew involved job prospects suddenly got better within NASA; but perhaps I'm too pessimistic of human nature.

-R


--

 -Ian     Motto: "You're Not Authorized to Know Our Motto."
         "Everything takes longer than you expect, even when you
          take into account Hofstadter's Law"   -  Hostadter's Law
         "The future isn't what it used to be, but then it never was."
"Predestination was doomed from the start." "Everything I say is a lie"




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