The United States currently is the only industrialized nation that has not designated SI as its official system of measurement.
The loss of NASA's Mars Climate Orbiter (MCO) in September 2000 due to a contractor using English rather than metric units of measurement in a navigation software program prompted the NASA Office of Inspector General to review the Agency's use of the metric system. By law and policy, the metric system is the preferred system of measurement within NASA. However, the Inspector General's review found that use of the metric system is inconsistent across the Agency. Also, the review found that little guidance is provided to employees on NASA's policy and procedures regarding the use of the metric system.