WE WILL probably never know what destroyed Beagle 2, the British-built lander that disappeared on Mars at the end of last year. That鈥檚 the conclusion of the Beagle 2 team鈥檚 own analysis of what may have gone wrong.
Nothing was heard from Beagle 2 after it separated as planned from the European Space Agency鈥檚 Mars Express craft on 19 December 2003 and headed for the planet鈥檚 surface. Among the failure scenarios listed in the report, published this week, is that it hit the ground too hard because the atmosphere on Mars may have been thinner than expected. Another suggestion is that the airbags designed to cushion the craft鈥檚 landing failed to work.
鈥淭he biggest surprise was the atmospheric variations,鈥� says Mark Sims, the mission manager from the University of Leicester in the UK. The evidence for a thinner than expected atmosphere comes from the NASA rovers Spirit and Opportunity, which landed on Mars shortly after Beagle 2鈥檚 demise. Data from the American landers during their descent suggests the atmosphere was less dense than computer models had predicted. Mars Express, which is still orbiting the planet, has also detected low atmospheric density. 鈥淭hat is the only thing for which we have any evidence,鈥� says Colin Pillinger of the Open University in Milton Keynes, UK, who played a leading role in the project.
Advertisement
The airbags could have failed because they either burst, or did not inflate properly. The bags had burst during crucial tests before the launch. Sims admits that they were never tested as thoroughly as the team wanted because of the cost of using test facilities in the US. Also, the team designed a new parachute at the last minute to reduce the craft鈥檚 landing speed, and it is possible that the parachute got caught up in the lander and its airbags, preventing them from deploying properly.
The report also sheds light on two oddities seen in photographs of the lander taken as it was released from Mars Express: a mysterious bright patch on the rear of the Beagle, and an object that seems to be floating away from it. The bright patch is roughly the size and shape of an access panel on the back of the spacecraft. If it had come loose and floated away, hot gases created as the craft entered the Martian atmosphere would have entered the craft and destroyed it. 鈥淲e examined this scenario and the feeling is that it was unlikely,鈥� says Richard Slade, of EADS Astrium, the company that managed the project.
The report even examined the possibility that the spacecraft was nudged off-course by the Martian moons. But this is unlikely to have caused the failure, it says. David Southwood of ESA, who oversaw the Beagle 2 project, praised the thoroughness of the report. 鈥淚t鈥檚 a terrific piece of work,鈥� he says.
