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Tension grows as European Mars craft readies for critical orbit

Posted on: Wednesday, 24 December 2003, 06:00 CST

FRANKFURT, Germany (AP) -- European controllers carried out final checks on the Mars Express spacecraft Wednesday before it fires into orbit around the Red Planet, the critical point of a finely calibrated two-part mission to probe the Martian surface for possible signs of life.

Commands to heat the craft's fuel tanks were sent through space in preparation for a 34-minute burn of its engine early on Christmas Day, European time, that is supposed to thrust it into orbit on Europe's first mission to Mars.

``From this point, the tension really starts to grow,'' flight director Michael McKay said in a statement. ``We don't have a lot more to do except watch and wait.''

Controllers also were switching off nonessential equipment on Mars Express in the hours before the engine firing. Orbit will pave the way for the craft to make contact with the Beagle 2 probe, expected to land on the planet's surface minutes earlier for a mission to probe rocks and soil for evidence of organic matter.

Shaped like an oversize pocket watch, the Beagle 2 is designed to fly through the Martian atmosphere, deploy parachutes and bounce to a landing on inflatable bags. Then it should open up, unfold its solar panels like the petals of a flower and begin sending a signal to let controllers know it has safely touched down.

The Mars Express orbiter is meant to send back overhead pictures of the planet's surface and scan for underground water with a powerful radar, as well as relaying information from the 67-kilogram (143-pound) Beagle 2, which it released toward Mars Friday.

Mars Express was some 200,000 kilometers (124,300 miles) from Mars mid-Wednesday and on course for the orbit maneuver, which was to be performed some 400 kilometers (250 miles) above the surface, mission control said.

While Beagle 2 is scheduled to touch down at 0245 GMT Christmas Day, it will be several hours before controllers get a chance to confirm its landing.

Mars Express won't be in place to pick up the signal until Jan. 3, so the first chance of contact will be when NASA's Mars Odyssey passes overhead at around 0515 GMT Dec. 25.

If that fails, scientists at Britain's Jodrell Bank Observatory will have a chance to train its radio telescope on Mars Thursday evening, European time, to try to pick up the signal.

The Odyssey orbiter, which reached Mars in 2001, will have a daily chance to pick up the signal until Mars Express can make its own first contact.

Mission control spokesman Bernhard von Weyhe said controllers were ``very confident'' of pulling off the much-rehearsed Mars Express orbit sequence, but said the Beagle 2 landing carries greater risks.

Still, he said controllers wouldn't be too concerned if no signal from Beagle 2 is detected Thursday.

``It doesn't have to mean anything,'' von Weyhe said. ``It can mean it needs more time to be unfolded, or it's at a funny angle.''

Beagle 2, named for the ship that carried naturalist Charles Darwin on his voyage of discovery in the 1830s, will conduct experiments by scratching the surface with a robotic arm to test for signs of organic matter.

It is expected to transmit its first pictures from Mars between Dec. 29-31. The first radar pictures from Mars Express are expected in the spring.

Scientists believe that Mars, which still has frozen water in its ice caps, might have once had liquid water and suitable conditions for life, but lost them billions of years ago. It is believed that water may also still exist as underground ice.

The European mission is the first search for signs of life on Mars since two U.S. Viking landers probed the planet in 1976 but sent back inconclusive results. Of 34 unmanned American, Soviet and Russian missions to Mars since 1960, two-thirds ended in failure. Japan this month abandoned a mission to determine whether Mars has a magnetic field after its Nozomi probe failed to hit planetary orbit.

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On the Net:

Mars Express: www.esa.int/export/SPECIALS/Mars--Express/index.html

European Space Agency: www.esa.int/export/SPECIALS/Mars--Express/SEMTERWLDMD--0.html

Beagle 2: www.beagle2.com

(gm-tc)

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