Jbuch said:One of the failedMarsmissions in the last five years was caused by
half of the engineering time working in theMetricsystem, and the other
half working in the English system, and back-converting the units to Metric.
The contract called for the use of theMetricsystem.
Indeed. The specification mandated metric units. The subcontractor,
Lockheed Martin,
Quoted message said: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."
www.hq.nasa.gov/office/codeq/risk/mco_mib_report.pdf
The US is increasing the use of metric units. The US military has been
metric for decades. The FAA switched aviation temperatures from
Fahrenheit to Celsius in 1996. Wine and liquor in the US has been in
metric sizes for a long time. For a decade, many pre-packed goods in
the US supermarket have been required to have metric units, as
mandated by the The Fair Packaging and Labeling Act.
Even the US President has been heard to quote volume in liters when
addressing Congress.
http://www.whitehouse.gov/news/releases/2003/01/20030128-19.html