The BBC's Sue Nelson: "The probe could only understand metric instructions"

This information was critical to the manoeuvres required to place the spacecraft in the proper Mars orbit.

"Our inability to recognise and correct this simple error has had major implications," said Dr Edward Stone, director of the Nasa's Jet Propulsion Laboratory (JPL). "We have underway a thorough investigation to understand this issue."

The confusion over units was identified in preliminary findings by JPL's internal peer review. The transfer of information took place between the Mars Climate Orbiter spacecraft team in Colorado and the mission navigation team in California.

"People sometimes make errors," said Dr Edward Weiler, Nasa's Associate Administrator for Space Science. "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."

Focus on future

Professor Fred Taylor of Oxford University: "It's still very puzzling"

Two separate review committees have already been formed to investigate the loss of Mars Climate Orbiter - the internal JPL peer group and a special review board of JPL and outside experts. An independent Nasa failure review board will be formed shortly.

"Our clear short-term goal is to maximise the likelihood of a successful landing of the Mars Polar Lander on December 3," said Dr Weiler. "The lessons from these reviews will be applied across the board in the future."

Mars Climate Orbiter was one of a series of missions in a long-term program of Mars exploration managed by JPL.