National Aeronautics and

Space Administration

Office of Inspector General


Washington, D.C. 20546-0001

Reply to Attn of: W February 20, 2001

TO: A/Administrator

FROM: W/Inspector General

SUBJECT: Assessment of NASA’s Use of the Metric System, G-00-021

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.

Based on our review, we made eight recommendations intended to improve the use of the
metric system within NASA in accordance with national policy and NASA guidance. We
recommended NASA:

  • reexamine the Agency’s effort to convert to the metric system and develop a new
    approach for converting to the metric system,

  • closely monitor technical interfaces between metric and English units,
  • reinvigorate the metric waiver system, and
  • use the metric system as the preferred system for interactions with the public.

Management concurred with all of the report’s recommendations, except the recommendation
that NASA use the metric system for interactions with the public. In responding to this
recommendation, management agreed to use metric units in all education programs and when
communicating with the public about programs that use metric or hybrid metric/English units.
However, the Public Affairs Office plans to use English units of measurement when
communicating about programs that use English units exclusively. We continue to hold that
since public law requires NASA to use metric units where economically feasible, the Agency
should use metric units in all communications with the public.

As the United States continues its slow transition to the metric system, NASA must decide
whether it wants to be a leader or a follower in the transition process. Both roles come with a
cost. If NASA chooses to push forward with the Agency’s use of the metric system, near-term
costs may increase and short-term risk (both to schedule and mission success) may rise

to some degree. However, if the Agency follows the aerospace industry’s slow transition to
SI, the protracted period during which NASA uses mixed metric and English systems may
further increase costs and risks for NASA programs.

NASA is the nation’s most visible science and technology agency, and is involved in highly
publicized cooperative projects with a world that almost exclusively uses the metric system.
Certainly an argument could be made that as the nation’s symbol of technological prowess,
NASA has a role in promoting acceptance and use of the metric system. We believe the
Agency should reassess its conversion to the metric system and determine the most
appropriate approach for the Agency to successfully transition to the metric system.

[original signed by]

Roberta L. Gross


Assessment of NASA’s Use of the Metric System, G-00-02

Full report available at