The loss of the Mars Climate Orbiter -- valued at $125 million -- because the contractor (Lockheed Martin Astronautics) supplied NASA with crucial data in U.S. customary units rather than metric units points to the unacceptable state of affairs in this country regarding metrication [front page, Oct. 1].

Starting in January, a European Union directive will go into effect, and only metric units will appear on products sold in the European Union. Reports that this deadline has been postponed to 2009 are erroneous. Only a proposal to postpone the deadline has been put forth, and the necessary governing bodies do not have enough time to act upon that proposal. Thus, business and trade associations are advising U.S. companies to remove all U.S. customary markings from their labels to be used on products exported to the European Union.

We must already use the metric system in manufacturing, science, technology and other areas, and it is inescapable that we must at some point convert to join the rest of the world in using the metric system in everyday life. The sooner we embark on a well-directed program to convert (such as those used successfully in Australia and South Africa), the better off we will be.

EZRA STEINBERG

Redwood City, Calif.

The loss of NASA's Mars Climate Orbiter was the second calamity to befall a U.S. spacecraft trying to attain orbit around Mars in the past six years. The failure to convert British to metric units should have been caught by NASA's quality control team. Or it might have been obviated by eliminating the need to convert.

NASA has always employed the metric system (grams and meters) in its scientific work. Most of NASA's industrial suppliers, however, have clung to the use of British units (pounds and miles) for measurements and manufacturing. The rest of the world, of course, uses the metric system.

In the mid-'80s, NASA made a valiant attempt to convert to the metric system. The agency decreed, and specified in the initial study contracts, that all work in the planned multibillion-dollar space station program would be in metric units. That rule lasted through the design phase, but when the time came to issue production contracts, the contractors raised such a hue and cry over the costs and difficulties of conversion that the initiative was dropped. The international partners were unhappy, but their concerns were shunted aside.

No one ever suspected that a measurement conversion error could cause a failure in a future space project. The use of British units in this country seems more entrenched now than ever.

BURT EDELSON

Chevy Chase