Facts can also be factual.
Kent K9ZTV
/On November 10, 1999, the Mars Climate Orbiter Mishap Investigation
Board released a Phase I report, detailing the suspected issues
encountered with the loss of the spacecraft. Previously, on September 8,
1999, Trajectory Correction Maneuver-4 was computed and then executed on
September 15, 1999. It was intended to place the spacecraft at an
optimal position for an orbital insertion maneuver that would bring the
spacecraft around Mars at an altitude of 226 kilometers on September 23,
1999. However, during the week between TCM-4 and the orbital insertion
maneuver, the navigation team indicated the altitude may be much lower
than intended at 150 to 170 kilometers. Twenty-four hours prior to
orbital insertion, calculations placed the orbiter at an altitude of 110
kilometers; 80 kilometers is the minimum altitude that Mars Climate
Orbiter was thought to be capable of surviving during this maneuver.
Post-failure calculations showed that the spacecraft was on a trajectory
that would have taken the orbiter within 57 kilometers of the surface,
where the spacecraft likely disintegrated because of atmospheric
stresses. /
/_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> /
//
/The discrepancy between calculated and measured position, resulting in
the discrepancy between desired and actual orbit insertion altitude, had
been noticed earlier by at least two navigators, whose concerns were
dismissed. A meeting of trajectory software engineers, trajectory
software operators (navigators), propulsion engineers, and managers, was
convened to consider the possibility of executing Trajectory Correction
Maneuver-5, which was in the schedule. Attendees of the meeting recall
an agreement to conduct TCM-5, but it was ultimately not done./
On 1/17/2015 1:41 PM, Lynn W. Taylor, WB6UUT wrote:
Good quip, but it doesn't agree with the findings of the Mars Climate
Orbiter Mishap Investigation Board.
Facts can be so inconvenient.
On 1/17/2015 11:15 AM, KENT TRIMBLE wrote:
Good quips always sail over at least one person's head.
K9ZTV
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