Confusion over the use of imperial and metric units caused the loss of the $125 million Mars Climate Orbiter spacecraft in late September.
The NASA spacecraft was lost just minutes after its orbital insertion engine was fired to place it in orbit around the planet. The failure on 23 September was caused by a mix-up between two project teams, one of which used imperial units and the other metric measures to input data critical to the manoeuvres required to place the spacecraft on the correct path.
Orbiter builder Lockheed Martin submitted acceleration data in pounds of thrust instead of in metric kiloNewtons. NASA's Jet Propulsion Laboratory in Pasadena, California, fed the numbers into the spacecraft's flight computer assuming that they were metric. The error had been embedded in the spacecraft since its launch last December.
"People sometimes make mistakes," says Edward Weiler, NASA's associate administrator for space science. The spacecraft is believed to have broken up or hit the surface of Mars.
Source: Flight International
