Imperial vs. Metric: NASA's Mars Orbiter Lost to a Unit Slip
The Mars Climate Orbiter (MCO) was lost in 1999 because Lockheed Martin software used Imperial units while NASA expected metric, producing a trajectory error that likely caused the $125 million orbiter to burn up near Mars (the Polar Lander, part of Mars Surveyor ’98, was doomed by the same unit-conversion slip). Postmortems blamed rushed processes and inadequate verification of unit conversions rather than a single contractor fault.