Nasa rocked by 'cover-up' over failed Mars trip

The failure of last year's $155m (£97m) Mars probe, the Polar Lander, was the result of a fatal design flaw that senior members of the Nasa engineering team knew about butcovered up, according to leaked findings of the official report.

The disclosure, which may or may not survive so baldly in the final, published report, is the latest scandal to hit the US space agency. Just four months ago, the official report on the loss of the earlier Mars probe, the $125m (£78m) Climate Orbiter, concluded it had burnt up in the Mars atmosphere because of an elementary miscalculation: metric and imperial units had been confused.

The loss of the Polar Lander three months later, however, is a far bigger indictment of Nasa operations, because it appears at least some of those involved in managing the project knew in advance that it was doomed.

Details of the report, which was due to be published at the end of the month but could now be released early, were obtained by James Oberg, a reporter with the news agency United Press International. His source described the findings as "devastating" for Nasa.

In practical terms, what they mean is that last year, when scientists around the world watched for the first signals to be transmitted from the Polar Lander's carefully selected soft-landing site on Mars, there were those in Nasa who knew they were waiting in vain. Thus the vast amounts of time and money that were spent on trying to track and then trace the Polar Lander were wasted. As long as two months later, researchers at Stanford University in California detected signals they thought might have come from Mars; Nasa did not correct them.

The flaw said to be identified in the report relates to the design of the Polar Lander's braking thrusters, which were said to repeatedly fail tests to operate in the temperatures likely to be encountered on the approach to Mars. Rather than modify or redesign the mechanism, managers decided to modify the test so that the thrusters would pass. "This happened in middle management," Mr Oberg was told. "It was done unilaterally with no approval up or down the chain of command."

Senior Nasa officials, according to Mr Oberg, learnt of the problem only days before the craft was due to land. It was too late to do anything about it and they decided to hope for a miracle. After a month's wait, they declared the probe lost.

This was the major, but not the only fault with the Polar Lander. Even if the thrusters had worked, the report is said to conclude, the landing gearwould probably have failed. Tests had not detected the fault because they were conducted by a separate team and in isolation from the space testing.

Observations about a lack of co-ordination between departments, managerial pressure to meet deadlines and a general shortage of experience andleadership peppered the earlier report on Climate Orbiter.

Nasa officials said yesterday there would be no comment on the findings before the official publication of the report, although the head of the agency's planetary programme, Carl Pitcher, told a conference last week "our ambition exceeded our grasp" and the findings made "sober reading". An advance copy is said to have been delivered to the White House for presidential scrutiny - and doubtless damage control.