Oxfordshire scientists remain baffled as to why the Mars probe they worked on disappeared over the Red Planet.

The fate of the £50m Beagle 2 probe -- part of which was designed by engineers at Rutherford Appleton Laboratory, near Didcot, is no clearer after a second inquiry report.

The project team was un- able to pinpoint why the mission failed on Christmas Day.

One theory is that unusually thin air over the landing site, probably caused by turbulent dust storms, disrupted the descent and landing systems.

As a result, Beagle 2's parachutes and cushioning airbags may have been deployed too late. Dr Bryan Shaughnessy, of RAL, the engineer who headed a small team responsible for the thermal design and testing of Beagle 2 said: "There are a lot of possibilities why Beagle 2 failed and the report lists some of those possibilities."

Dr Shaughnessy said RAL achieved important and invaluable science on Beagle 2, before it reached the launch pad, including helping miniaturise instruments that would have filled a laboratory into the size of a shoe box.

They had the responsibility of ensuring that the spacecraft was able to survive its journey and the hostile temperatures and conditions it would have experienced on Mars.

To help design the probe, Dr Shaughnessy and colleagues used computer models to recreate the effect of the extremes of temperature that Beagle 2 was expected to experience. And a replica of the Beagle 2 was tested in a three metre diameter space test chamber at the Chilton laboratory.

Dr Shaughnessy said it was the first time a Martian environment had been recreated in a test laboratory in Europe.

Meanwhile, he said the Mars Express mother ship was still orbiting Mars and producing great results from instruments including Aspera in which Prof Manuel Grande of RAL was involved. Aspera is looking at whether there has been water on Mars.

didcot@nqo.com

Yesterday's report which includes contributions from Dr Shaughnessy said: "Improved characterisation of the Martian atmosphere is, in the view of the Beagle 2 team, critical to the success of future missions."

An instrument on the Mars Express spacecraft which ferried Beagle 2 to the Red Planet showed evidence of unusually low atmospheric density.

But falling through a thin atmosphere was not the only possible cause of failure identified by the report.

The team said despite rigorous testing, a number of potential system malfunctions could not be ruled out.

They included electronic glitches, a gasbag puncture, a failure of Beagle 2 to deploy its instruments, damage to the heat shield, and a broken communications antenna.

It was also possible that Beagle 2 hit an unforeseen hazard on the ground.

Beagle 2 separated successfully from Mars Express on December 25 and appeared to be on course for a textbook landing. But then all contact with the £50 million craft was lost.

Two sets of findings were published by the Beagle 2 team yesterday -- one looking at possible reasons why the mission failed and the other listing lessons learned.