Europe selects landing site for Mars probe

larger   Satellite image of the landing site

By Richard Stenger
CNN.com Writer

(CNN) -- The Mars Express lander will touch down on a gently sloping region north of the equator on Mars, the European Space Agency announced Wednesday.

The Beagle 2 will hitch a ride on the Mars Express spacecraft and touch down in 2003 in the Isidis Basin, where it will sniff air, dig dirt and bake samples for evidence of past or present life.

The landing site, officially selected last week after months of deliberation, lies on the boundary between ancient highlands and northern plains. The area could be a sedimentary basin that preserves fossils of primitive life if it existed, according to ESA.

"It's a nice middle-of-the road site. There's enough rocks to be confident we will land near something that we can sample. But not so many that they would wreck the spacecraft when it lands," said Beagle 2 scientist Colin Pillinger.

Moreover, the elevation is low enough for the small probe's parachute to brake as it descends for a landing. The location will also be warm enough for the lander's instruments to work properly when it arrives in the early martian spring. Other candidate sites would have been too cold, Pillinger said.

Beagle 2 scientists considered additional areas imaged by NASA's Mars Global Surveyor satellite. Earlier this month, U.S. scientists looking at pictures taken by Surveyor identified locations with possible sedimentary deposits that could contain fossils of ancient martian life, if they exist.

Artist's concept of the Beagle 2 on Mars

"Unfortunately, this layered terrain is revealed in steep, narrow canyons, which are unsuitable (for landing)," Beagle 2 researcher John Bridges told Mars Express scientists last week.

To increase the chances that the probe lands safely, ESA scientists selected the final site based on a landing window that extends 500 km by 100 km (310 miles by 62 miles).

The Mars Express lander and orbiter are due to arrive in the Mars system in December 2003. When Beagle 2 lands shortly thereafter, it could find robotic company on the surface.

NASA plans to land two rovers on the red planet at roughly the same time. The mobile laboratories will search for signs of water. No sites have been selected yet for the twin NASA missions.

To search for samples, Beagle 2 will use camera eyes to guide a robotic arm to a suitable rock. It will then drill and retrieve a core sample from the interior of the rock and place it under intense heat in the presence of oxygen.

Despite their differences, the ESA and NASA missions have some common features. Each will land with a bounce, cushioned by inflatable airbags. Each will use grinders to remove the weathered surface of rocks and expose their pristine interiors.

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Beagle 2
NASA
European Space Agency

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