The women and men behind the mission to Mars

The landing site

Dave Rothery, senior lecturer in earth sciences at the Open University

On December 26, Beagle 2 will come to rest on the barren surface of Mars. By then, the first phase of Dave Rothery's work with colleagues John Bridges and Ashley Seabrook will be long complete. Their selection of landing site is critical to the mission's success. In fact, the choice was rather limited, Rothery admits: it had to be low-lying to provide sufficient depth of atmosphere to slow the probe's descent, in the northern hemisphere so Martian spring sunlight would flood the solar panels and in a location where dust storms are rare. The abundance of rocks was another factor. Too many, Rothery says, and the airbags that cushion Beagle 2' s touchdown might rupture. Too few and there might not be any within reach of the sampling device. The team finally selected the Isidis Planitia Basin.

They are now characterising the site. Rothery notes: "As things have panned out, it looks a very interesting place." Among the basin's features are a lot of volcanic cones that might melt subsoil ice and possibly provide a refuge for life.

The eyes

Andrew Griffiths, project manager at University College London's Mullard Space Science Laboratory

Three days after touchdown, Beagle 2 will start surveying its immediate surroundings in sufficient detail to create a three-dimensional computer model of this tiny corner of Mars. The stereo camera system that Andrew Griffiths' team has been working on will use two CCDs behind radioaction-proof glass to scan the terrain. Every rock, pebble, bump and hollow on the square metre of dusty ground centred on Beagle 2 will be plotted and, most likely, named. The scientists will be guided by the accuracy of that model as the probe's robotics cannot be controlled in real time from the Earth. Every move of the robot arm will have to be rehearsed on a to-scale rapid prototype model of the terrain created in the UK. The cameras will also analyse sunlight for atmospheric water vapour while Griffiths is keen to train them back towards the earth to capture a haunting image of our world.

The nose

Jenny Stewart and Geraint Morgan, project specialists at the Open University

In essence, Beagle 2 is a mass spectrometer with a mighty wanderlust. It is the device that will "sniff" out signs of life on Mars. Much of the technology was pioneered by Colin Pillinger during a career that has involved analysing many extraterrestrial rock samples, including Apollo moon dust and Nasa's celebrated Martian meteorite. Geraint Morgan and Jenny Stewart have helped hone the technique for the mission's requirements. "We're effectively taking our laboratory to Mars," Morgan says.

The gas analysis package or Gap contains instrumentation that would usually take up an entire lab. Stewart and Morgan have just 5.2kg and 60 watt hours a day of power - enough to power a lightbulb for an hour.

Among other substances, Gap will detect very low quantities of carbon, the element that is the basis of terrestrial life. Martian soil samples will be heated in oxygen so any carbon compound present will burn to produce carbon dioxide. This will then be analysed by the spectrometer and could reveal the presence of organic molecules. A more sensitive analysis of the relative abundance of stable carbon isotopes should further betray the signature of life in those chemicals.