(Stuf4) writes:

From Jeff Findley:
(Stuf4) writes:

I would agree that the chances of a shuttle crashing due to a software
glitch is very small. The point was why take a chance when you have
proven flown software available? It becomes a risk trade with any
potential safety gains in the new version.

Because the benefits of the bug fixes and enhancements to the software
might just outweigh the risks, especially considering the high level
of quality in this particular software development group.

I acknowledge validity to that argument. But I hope you see that it
also skirts an "if it isn't broken, fix it anyway" philosophy.

The devil is in the details. My point is that you have to look at
what fixes and functional enhancements are in the (extensively ground
tested) new version and compare that to the existing flight tested
version. The flight tested version may very well have known problems
and functional deficiencies that directly or indirectly impact flight
safety.

In the end, you can never improve on the released verion of software
unless you ship patches and/or new versions. When doing so, you
typically run all sorts of "regression testing" and don't allow the
new version to ship with known regressions. This "regression testing"
suite would typically contain all of the tests possible. In the case
of STS software, I'm sure the regression testing is extensive.

Jeff
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