Lee wrote:
>>Even that lack of understanding inside the U.S. has
>led to a multimillion dollar crash on Mars.
>
>That crash was caused by the complete failure to
>specify the measurement system, not by
>misunderstanding "standard" vs "metric".
The specification mandated metric units. The subcontractor, Lockheed
Martin, failed use metric units.
The official report says:
"The MCO MIB [Mars Climate Orbiter Mishap Investigation Board] has
determined that the root cause for the loss of the MCO spacecraft was
the failure to use metric units in the coding of a ground software
file, "Small Forces," used in trajectory models. Specifically,
thruster performance data in English units instead of metric units was
used in the software application code titled SM_FORCES (smallforces).
The output from the SM_FORCES application code as required by a MSOP
Project Software Interface Specification (SIS) was to be in metric
units of Newton-seconds (N-s). Instead, the data was reported in
English units of pound-seconds (lbf-s). The Angular Momentum
Desaturation (AMD) file contained the output data from the SM_FORCES
software. The SIS, which was not followed, defines both the format and
units of the AMD file generated by ground-based computers."
http://www.hq.nasa.gov/office/codeq/...mib_report.pdf