Page last updated at 21:58 GMT, Wednesday, 17 December 2008

Flaw theory over Mars Beagle loss

By James Morgan
Science reporter, BBC News

Beagle 2, European Space Agency
The British-built probe was lost on Mars in 2003

Britain's ill-fated Mars probe, Beagle 2, may have met a fiery end through a miscalculation, New Scientist reports.

The spacecraft, built to find signs of life, vanished on Christmas Day 2003.

A simulation by Queensland University scientists suggests the probe went out of control during its descent due to a misjudgement of the Martian atmosphere.

The new theory was welcomed by Professor Colin Pillinger, Beagle 2 team leader, but he said the figures in the study were "far from conclusive".

The spin rate was just too high. It counteracted the stabilisation you'd expect
Dr Madhat Abdel-Jawad,

Queensland University

"We are as interested as anybody to find out the truth," he told BBC News.

"But until we go through the calculations in this new paper and check them against our own, we can't really comment.

"What I can say is that everything that went into the Beagle 2 programme was very carefully calculated."

In a spin

"We still think we got it right," said Arthur Smith, one of the chief engineers on Beagle 2, who works for Fluid Gravity Engineering.

"Of course, we will now look at our calculations again, very carefully. We will run these new simulations and see if they cause Beagle 2 to [spin out of control].

"But I don't think they do. That remains our position at the moment.

"If it turns out we did miscalculate, we would be very upset. But it is important for us to know, so that we can learn from it."

Until now, experts have assumed that the probe, part of the European Mars Express mission, suffered a major equipment malfunction or encountered unexpected conditions that caused it to burn up or "bounce off" the Martian atmosphere.

Parachute failure, loss of radio communication, and high levels of atmospheric dust have all been suggested as possible reasons for the spacecraft's loss.

Now a team of Australian engineers have come up with another explanation - an incorrectly calculated "spin rate".

One thing is for sure; this is not the last we will hear about Beagle 2
Colin Pillinger

Beagle 2 was made to spin as it detached from its "mothership", the Mars Express orbiter, to stabilise its descent through the Martian atmosphere.

The ideal spin rate was difficult to determine because forces on the spacecraft would have changed as it plunged from the planet's thin upper atmosphere to denser regions closer to the surface.

Beagle 2 scientists duplicated the forces at work in "thin" and "thick" parts of the Martian atmosphere but did not have the resources to simulate what happened during the transition between the two.

Instead, they estimated the transitional forces using a mathematical process called a "bridging function".

In the end, they settled on a spin rate of 14 revolutions per minute.

Burning up

The Australian experts, led by Michael Macrossan and Madhat Abdel-Jawad at the University of Queensland in Brisbane, have now been able to simulate the atmospheric "transition" state Beagle 2 is likely to have encountered.

They conclude it is clear that the craft was spinning too fast. As the Martian air thickened, this would have caused it to tumble out of control and burn up just seconds after dropping into the atmosphere.

"The spin rate was just too high," Dr Abdel-Jawad told New Scientist.

"It counteracted the stabilisation you'd expect."

His study is published in the Journal of Spacecraft and Rockets.

But is this the most convincing theory yet for the disappearance of Beagle 2?

"I would say not," said Arthur Smith. "It would not be top of my list."

"One thing is for sure," added Professor Pillinger, "this is not the last we will hear about Beagle 2."

Professor Pillinger is now working on the European Space Agency's Rosetta mission.

The robotic spacecraft, launched in 2004, is intended to study the comet 67P/Churyumov-Gerasimenko.

"If this one goes pear-shaped, I shall not be best pleased," he said.

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