"3. RATIONALE: This directive defines and communicates a consistent approach to the use of engineering units throughout CxP. The program conducted an extensive and detailed effort to implement a primary SI units based system for design, analysis, test and operations while allowing English units for most of the hardware. This effort looked at various implementation strategies and worked the implementation details to the point of having workable implementation plans in all the projects. However, the cost estimates to achieve these plans significantly exceeded the resources that could be made available in the critical years. Therefore, given budget constraints and the need for consistent practice of units throughout the CxP lifecycle to minimize risks and to achieve mission success, the program is revising its previous management directive to a primarily English units based program with limited usage of SI as defined in the MD. This MD constitutes the basis for the waiver to NASA policy directing the usage of SI."
"Following the loss of the Mars Climate Observer, the NASA Office of Inspector General initiated a review of the Agency's use of the metric system. By law and policy, the metric system is the preferred system of measurement within NASA. However, our review found that use of the metric system is inconsistent across the Agency. A waiver system, which was required by law and put into effect to track metric usage and encourage conversion, is no longer in use. In addition, NASA employees are given little guidance on the Agency's policy and procedures regarding use of the metric system."
"b. All new programs and projects covered by NPR 7120.5 shall use the SI system of measurement for design, development and operations, in preference to customary U.S. measurement units, for all internal activities, related NASA procurements, grants, and business activities. Exceptions to this requirement may be granted by the NASA Chief Engineer based on program/project recommendations by the responsible Mission Directorate Associate Administrator where use of SI units is demonstrated to be impractical, adds unacceptable risk, or is likely to cause significant inefficiencies or loss of markets to U.S. firms. Special emphasis shall be placed on maximum use of SI units in cooperative programs with international partners."
Keith's note: NASA claims that it wants to have meaningful international participation in the implementation of VSE/ESAS yet it walks away from the system of weights and measures used by the majority of the people on this planet. Moreover, this decision clearly seems to fly in the face of established NASA - and Federal - policy.