Nasa engineers knew about a fatal design flaw with the Mars Polar Lander's braking thrusters but kept it secret, leaked information claims.
It follows persistent rumours that the disappearance of the MPL spacecraft last December was no surprise to Nasa officials.
An independent report on the loss of MPL has been produced by retired aerospace executive Thomas Young. This has been sent to the White House before being made public.
The document is said to reveal a catalogue of management errors and misjudgements. But a source, described as close to the investigation, has also come forward to claim that MPL's braking thrusters failed tests during their construction.
Cold temperatures
These tests apparently showed that the system used to ignite the craft's hydrazine fuel could not operate effectively at the cold temperatures expected during the flight to Mars. This would seriously have compromised the performance of the thrusters.
But rather than begin an expensive redesign and replacement program, an unnamed space official is said by the source to have altered the test conditions to make it look as though the engines would perform in the conditions expected.
According to the UPI news agency, senior Nasa officials only realised the flaw in MPL's thrusters a few days before the landing was to take place on 3 December - when it was too late to do anything about it.
James Olberg, UPI's science writer, told the BBC: "The engineers came to the conclusion that MPL wasn't going to work, but they didn't want to tell anyone about it. They said: 'We're already in flight, we've checked it out, there's nothing we can do on the ground - let's think some good thoughts and hope for a miracle'."
Devastating critique
The MPL investigation has also reportedly identified a second fatal design flaw that would have doomed the probe even if the engines had worked properly.
Nasa will not comment about the report ahead of its publication but it has taken issue with the claim that parameters were changed to allow the thrusters to pass their tests.
As reported by BBC News Online, Dr Carl Pilcher, head of Nasa's planetary programme, told space scientists at last week's Lunar and Planetary Science Conference in Houston that as far as Mars was concerned, "our ambition exceeded our grasp".
Nasa chief Dan Goldin recently told his managers that the MPL report will be "the Rogers Commission of space science", referring to the devastating critique delivered by a panel that examined the 1986 Challenger disaster.
In a recent internal memo, Ed Stone, director of the Jet Propulsion Laboratory, which managed MPL, said: "The days ahead may at times be difficult."