Volume: 01, Issue: 18 12/03/2003 
Artistic depiction of the Beagle 2 lander descending towards the Martian surface.
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Artistic depiction of Mars Express orbiter disengaging the Beagle 2 lander.
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Other Articles in This Issue:
Stardust Pinpoints Where the Wild Thing Is
California 17-Year-Old Launches Attempt to be First Teenager in Space
NASA Successfully Tests Ion Engine
The Microbial Menace from Space
Chat Online about the Centennial of Flight with Dr. Jack Bacon

Dreaming of a Red Christmas

The European Space Agency's (ESA) Mars Express probe is scheduled to arrive at Mars at Christmas: the Beagle 2 lander is expected to touch down on the surface of the Red Planet during the night of Dec. 24 and 25.

Launched June 2, 2003 from Baikonur (Kazakhstan) onboard a Russian Soyuz operated by Starsem, the European probe—built for ESA by a European team of industrial companies led by Astrium—carries seven scientific instruments that will perform a series of remote-sensing experiments designed to shed new light on the Martian atmosphere, structure and geology. In particular, the British-made Beagle 2 lander will contribute to the search for traces of life on Mars through exobiology experiments and geochemistry research.

Onboard Mars Express, tests have been run to check that the instruments are functioning correctly. Mars Express has successfully come through its first power test on the whole spacecraft after the gigantic solar flare on Oct. 28. Since Nov. 17 the onboard software has been "frozen" after several updates, and the spacecraft is now quietly proceeding to its destination.

Before even entering into Martian orbit to perform its mission, Mars Express has to face another challenge: safely delivering the Beagle 2 lander to its destination. This task, starting on Dec. 19, will not be without risk. First of all, to deliver the lander where planned, Mars Express has been put on a collision course with Mars, since Beagle 2 does not have a propulsion system of its own and must therefore be carried precisely to its destination. This means that after separation, Mars Express has to veer away quickly to avoid crashing onto the planet.

During the cruise, Beagle 2 will take its power from the mother spacecraft, Mars Express. After separation and until its solar arrays are fully deployed on the surface, Beagle 2 must rely on its own battery, which cannot last beyond 6 days. So, like a caring parent, Mars Express must release Beagle 2 at the last possible moment to ensure that the lander has enough power for the rest of its journey to the surface.

Only then can Mars Express change its orientation and rapidly fire the thrusters to get away from the collision course and enter into orbit around Mars. This will be the first time that an orbiter delivers a lander without its own propulsion onto a planet and attempts orbit insertion immediately afterwards.

Since all these maneuvers are time-critical and allow little margin of error, the ground control team has had to simulate all possible scenarios (including glitches and problems, onboard and on the ground) to make sure nothing is left to chance.

The team has been training since September in a realistic setting, using the same computers and equipment that will be employed during this mission phase. Although the real spacecraft cannot be directly involved, its behavior is simulated via a sophisticated computer program, using the actual flight software. These rehearsals, each lasting a day or more, cover all possible situations, from the failure of an onboard instrument to the outbreak of a fire in the control room.

ESA's ground control team at ESOC, on the other hand, are extremely busy. They are actively rehearsing responses to any situation that might arise when Mars Express releases Beagle 2 and enters into orbit around Mars.

"The Mars Express mission is pushing the operations staff to extremes," said Gaele Winters, ESA Director of Technical and Operational Support. "Over the years, the experience acquired with experimental missions has provided a solid basis on which to prepare for the unexpected. The satellite controllers will rise to this new challenge."

For more information and an Advent calendar style countdown to the Martian touchdown, visit:

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