Mars Orbiter Loss Linked to Math Mistake

Newsday - Ithaca Journal
October 1, 1999

Washington - The loss of the Mars Climate Orbiter as it approached Mars last week is being blamed on a goof that could have tripped up a novice science student - confusing English and metric units.
    A preliminary investigation has found that two spacecraft teams - one at NASA's Jet Propulsion Laboratory in Pasadena, Calif., and the other at a Lockheed Martin facility in Colorado where the spacecraft was built - unknowingly were exchanging some vital information in different units of measurement.
    Thomas Gavin, deputy director of space and earth sciences at JPL, said in an interview Thursday that the mistake involved information being used to make tiny corrections in the spacecraft's orientation during its 9�-month cruise to Mars.
    Twice a day during the cruise to Mars, tiny thrusters on the spacecraft were fired briefly to counteract the effects of solar wind and other forces on the spinning of the flywheels.  The spacecraft team in Colorado used English units called pound-seconds to describe the small forces.(bad physics writing)
    That data was shipped via computer to JPL where the navigation team was expecting to receive the information in newton-seconds, a metric measure of force. (bad physics writing)
    Two Cornell University scientists calibrated the camera on the spacecraft, but neither scientist had any involvement in the measurement mistake.