This needs to stop here, but since Kent is saying that I don't
understand, I'm going to reply. Once.
We were talking about how a hypothetical airliner control system would
have two different programs, written by different groups, running
parallel, with either program capable of flying the plane. Part of the
flight system could crash that the pilots and passengers would not
notice. Airplanes in flight have to have controls that work in
milliseconds without a glitch.
With MRO, we have Lockheed software doing navigation, but not "flying"
the spacecraft. JPL software flew the spacecraft, but did not
navigate. If JPL did their own redundant navigation, the error would
have been caught.
It's not like they didn't have time, there was a week between the
calculation and the burn.
The facts in the Wikipedia article are correct, it just doesn't describe
a system that has any redundancy.
I will not comment further on this topic on list. We're way over the
limit on off-topic posts.
73 -- Lynn
On 1/17/2015 12:30 PM, KENT TRIMBLE wrote:
Facts can also be factual.
Kent K9ZTV
/<snip>/
/_The primary cause of this discrepancy was that one piece of ground
software supplied by _Lockheed Martin
<http://en.wikipedia.org/wiki/Lockheed_Martin>_produced results in a
_United States customary unit
<http://en.wikipedia.org/wiki/United_States_customary_units>_("American"),
contrary to its Software Interface Specification (SIS), while a second
system, supplied by _NASA <http://en.wikipedia.org/wiki/NASA>_, that
used those results expected them to be in metric units, in accord with
the SIS. _Software that calculated the total impulse produced by
thruster firings calculated results in pound-seconds. The trajectory
calculation used these results to correct the predicted position of
the spacecraft for the effects of thruster firings. This software
expected its inputs to be in newton-seconds.^[16]
<http://en.wikipedia.org/wiki/Mars_Climate_Orbiter#cite_note-Mishap-17> /
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