Return of the Beagle

Colin Pillinger is back in business. The leader of the ill-fated Beagle 2 mission is confident many of the elements he and the

’s space researchers have proposed for

’s next trip to Mars will be included in a 2011 mission.

European space scientists announced this month they intend to launch the new mission to the planet, due to arrive in 2013, as part of ESA’s Aurora programme.

The announcement followed a two-day workshop at Aston University, organised by the UK’s Particle Physics and Astronomy Research Council (PPARC) and ESA.

Three candidate missions were considered at the meeting — ExoMars, with an orbiter and a rover; a scaled-down version known as ExoMars-Lite with just a rover; and BeagleNet, a mission building on Beagle 2 and the cancelled French Netlander project, with two landers each with their own micro rovers.

In the end the scientists decided to merge the best elements of each of the three proposals into a new mission, although how ESA will do this remains anyone’s guess.

So far what has been decided is that the mission will carry a range of scientific instruments designed to detect signs of past or present life on the planet, and to identify any hazards to future manned Mars missions. The project will also help to prepare for a more ambitious mission in 2016 with NASA, to bring back a Mars sample to Earth.

Pillinger, professor of planetary sciences at the Open University and leader of the Beagle 2 mission, said the instruments onboard the lander will include many of those the BeagleNet team has pushed for.

‘It’s pretty clear that there are three things from BeagleNet: the sub-surface sampling, the detection of life experiments and the gas analysis package,’ he said.

This GAP instrument, which was carried onboard the Beagle 2 and according to Pillinger remains competitive with anything the US has, is capable of studying stable isotopes in the atmosphere, rocks and soil.

The rover is also likely to include a drill capable of penetrating the surface to a depth of 2m, and an instrument to measure seismic activity and help determine if methane detected in the atmosphere is produced by volcanic activity or as a by-product of living organisms.

One major decision yet to be made is whether to send one or two landers to the planet. Launching two landers on the Russian Soyuz rocket would mean fewer scientific instruments can be taken along.

But Pillinger argues two landers would decrease the risk of failure, by allowing for feedback on the entry, descent and landing from one to the other.

‘Mars is a very daunting place to go to. Its only got one per cent of our atmosphere and it’s an atmosphere we don’t understand very well. We can still fail to land on Earth, as we showed with the Genesis probe back in September, so I’m a great believer in the philosophy that since Europe has not succeeded in landing on Mars once yet, we ought to be trying twice,’ he said.

One option that would help to reduce the risk of the lander crashing into the surface of the planet, which both Pillinger and Dr Mark Sims, chair of PPARC’s Aurora Advisory Committee, have been promoting heavily, is for the lander to detach itself from the spacecraft within the Mars orbit.

This would be around 12 to 24 hours before landing, rather than six days as with Beagle 2.

Sims, research fellow for space projects and instrumentation at the University of Leicester’s Space Research Centre and former Beagle 2 mission manager, said this would result in a lower energy entry, reducing the heat load on the aeroshell, and allow the team to wait for the best atmospheric and landing site conditions.

‘In principle — though with quite a lot of limitations — you can even re-target a different landing site when in orbit, and if you’re prepared to stay in orbit long enough you can actually choose the local true solar time of landing.

‘So if you land in the early morning, between two and five o’clock, you get the highest-density atmosphere, lowest winds, lowest turbulence and, providing you can last until dawn, the maximum battery charge before the next Mars night,’ he said.

Another advantage of detaching in orbit is that there is no need for a low-power, long-duration timer to wake the lander up a few hours before it hits the atmosphere — another of the more risky elements of the Beagle 2 mission.

If the lander is released 12 to 24 hours before landing it could operate on its battery with all the systems running continuously, said Sims.

Whatever form the mission takes, it will be as conservative as possible in its entry, descent and landing, in a bid to avoid Beagle 2’s fate. To this end the lander will be in constant communication during its descent, something budget, space and mass constraints meant Beagle 2 was unable to do.

‘The new mission will have telemetry throughout entry, descent and landing, both in terms of data to an orbiting spacecraft and direct-to-Earth communication with a tone saying “I’m still alive, I’ve got to this part of the sequence,”’ he said.

Beagle 2 was also forced to rely on accelerometers and a timer to detect the critical point at which the pilot parachute should be deployed. The 2011 mission will use multiple measurements for the lander’s entry, descent and landing, he said.

Finally, extensive testing of the lander’s airbags will be carried out, although no decision has yet been made as to whether it will be fitted with vented or ‘bouncy’ airbags.

The latter allow the lander to bounce several times and therefore carry the risk of it bouncing in an unplanned and dangerous direction.

Vented airbags, on the other hand, compress the gas on impact with the ground and release it to allow energy to be reduced without the lander bouncing uncontrollably. These are being developed for ESA in a study by Oxford-based Vorticity, which is planning tests under Earth conditions later this year as part of the Aurora programme, although not for a particular mission.

The debate over which technologies to use is likely to continue both inside and outside ESA for the next two months.

A draft proposal must be ready by the end of June to allow the mission to be finalised and details sent out for ministers to consider ahead of ESA’s ministerial council meeting this December.

EADS Astrium, which has carried out one of three parallel industry studies to prepare for the mission and confirm its target budget of £350m, said ESA would shortly be issuing requests for proposals for the next stage of the project.

Ultimately the content of the mission will probably come down to cost, said Sims.

‘The message is clear that the [space] community wants to go in 2011, so the question is what we can develop in that time and what we can afford to do — and the jury’s still out.’