The Mars Climate Orbiter (MCO) was part of a NASA program to gather information on Mars. On December 11, 1998 the MCO was launched. The aim was for MCO to circuit Mars in a spherical orbit and perform measurements regarding the atmosphere and the climate of the planet. However, there was a problem during the maneuver and the space probe came too close to Mars and was lost.

The navigation problems resulted from the use of different units for calculations by the involved institutions. While the navigations team used the metric system, Lockheed Martin Astronautics, the American company that had produced the probe, used Anglo-American units of measurement. The conversion of the units (e.g. Newton-seconds vs. pound-seconds) was not always taken into account, thus leading to errors in course corrections.

In fact, NASA had made it clear in its "software interface specification" that the metric system should be used. The course correction program SM_FORCES by Lockhead Martin Aeronautics was not written in accordance with the official specifications and caused the loss of the spacecraft.

The story shows that the use of well-established standards is a major pre-requisite for successful projects. This is especially important in projects with international partners from countries that use a system of measurement that is not based on the International System of Units (SI units), e.g. USA. The use of standards is also important for the comparability and traceability of projects. The use of a double-check system also helps to ensure consistent implementation of specifications.