In about a year's time it should be exploring the surface of the Red Planet.
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Is this the first step towards knowing whether we are alone in the Universe?
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Prof Colin Pillinger
The 60-kilogram probe, constructed by a team led by Professor Colin Pillinger of the Open University, has to be ready to join the space craft that will carry it to Mars by the end of January.
Beagle 2 will hitch a ride on the European Space Agency's £110m Mars Express mission, due to take off in June from Russia's Baikonur launch site in Kazakhstan.
Professor Pillinger said: "This is a device which is built to try and answer a very fundamental question - is there life elsewhere in the Solar System?
"More importantly is this the first step towards knowing whether we are alone in the Universe?"
Work of art
Beagle 2 will be dropped on to the Martian surface to investigate the red rock and soil, and to look for signs of life.
It will conduct tests on minerals and rocks using its array of scientific instruments.
Signs of carbon isotopes on land or traces of methane gas in the atmosphere would be an exciting discovery. Both are hallmarks of biological processes and suggest life may once have existed beyond Earth.
As well as scientific equipment, Beagle 2 also carries artwork by Damien Hirst and music by Alex James and Dave Rowntree from the band Blur.
The total cost of the disc-shaped craft - the smallest soft-landing spacecraft ever - has not been revealed.
Professor Pillinger told reporters on Thursday it was "in the region" of £30m, although many services were provided free or at low cost by the space community.
Esa has said the final delivery date for Beagle 2 is 30 January. It will be integrated with the main space craft in Toulouse, southern France, before being shipped to Baikonur.