"People sometimes make errors," said Dr. Edward Weiler, NASA's associate administrator for space science. NASA officials said a simple miscommunication over different measurement standards – metric versus US – by teams controlling its Mars Climate Orbiter likely caused last week's loss of the spacecraft.

"The peer review preliminary findings indicate that one team used English units [inches, feet and pounds] while the other used metric units for a key spacecraft operation," said a statement released Thursday by NASA's Jet Propulsion Laboratory at the California Institute of Technology.

The highly anticipated probe was slated to begin orbiting Mars early in the morning on 23 September. NASA officials lost communication with the Mars Climate Orbiter at around 5:30 a.m. EDT that day after the craft disappeared behind the red planet at a far lower altitude than researchers had intended.

NASA officials said they believe the problem was probably caused by a miscommunication on measurement between the Mars Climate Orbiter spacecraft team in Colorado, and the mission navigation team in California.

"The problem here was not the error, it was the failure of NASA's systems engineering, and the checks and balances in our processes to detect the error. That's why we lost the spacecraft," said NASA's Weiler.

NASA officials said that the mix-up caused the craft to draw to within 60 km of the Mars instead of the expected 150 km, ruining the mission.

"Our inability to recognize and correct this simple error has had major implications," said Dr. Edward Stone, director of the Jet Propulsion Laboratory.

NASA spent approximately US$94 million to build the Orbiter.

The spacecraft, launched in December 1998, was going to study Mars' geography and weather patterns.

The craft was also expected to serve as a communications relay station for the Mars Polar Lander, scheduled to land on the planet on 3 December.

See also: Mars Probe Feared Destroyed

See also: Mars Probe Feared Destroyed