Tue, Dec 30, 2003 - Page 7 News List

Sunday offers best chance yet to spot a stray Beagle

RED PLANET Mars Express is being put into a polar orbit so that it passes regularly over the lander, giving scientists their best shot at picking up Beagle's signal


Anxious scientists now believe that their best chance of getting in touch with Beagle 2 -- the little British spacecraft so far stubbornly silent on the surface of Mars -- is on Sunday, when its mothership passes overhead.

Right now, the European Space Agency's Mars Express is in a huge elliptical orbit around the red planet. Its engines will fire for three minutes today and the craft should slip into a polar orbit, passing regularly over the Beagle.

"We haven't yet played all our cards," said David Southwood, the space agency's director of science.

"With Mars Express we will be using a system that we have fully tested and understand. At the moment, I am frustrated rather than concerned," he said.

Beagle, the lander designed to search for signs of life on Mars, reached the planet on Christmas Day after a 400-million-km journey, equipped with a transmitter about as powerful as a mobile phone.

Since then -- and assuming it landed in one piece -- it may have been fitfully trying to relay a message back to Earth via a NASA spacecraft, Mars Odyssey, perhaps mistiming its call on each overhead pass.

Colin Pillinger, the UK scientist who spent six years and raised ?50 million (US$88.7 million) to place Beagle on Mars, said: "We need to get Beagle 2 into a period when it can broadcast for a much longer period. This will happen around Jan. 4 after the spacecraft has experienced a sufficient number of communication failures to switch to automatic transmission mode."

Beagle was meant to be a pioneer and a scene stealer, but it will have to share the limelight. Sunday is the day the full-scale assault on Mars begins.

Mars Express itself carries a camera which will photograph the Martian landscape to a resolution of 2m -- small enough to spot Beagle's discarded parachute or the airbags that should have cushioned its fall -- and radar that can penetrate up to 5km below the Martian surface, to detect underground rivers, aquifers and permafrost.

And on Sunday, the first wave of a new American invasion begins. A Mars exploration rover called Spirit will go through the same violent tests that faced the Beagle. Spirit will slam into the Martian atmosphere at 19,000kph, slow to 1,600kph, and then open a parachute to slow it to 300kph, at about 100m above the ground. But Beagle weighed only 68kg, and was designed to carry on falling until it bounced to a halt.

Spirit weighs 827kg, prompting the American lander to fire retro-rockets to lower its descent speed to zero before it inflates its airbags and resumes its fall, hitting the ground at 50kph. The whole descent will take six minutes.

Unlike Beagle 2, which to save power arrived on Mars in silence, Spirit will talk to engineers back on Earth at each stage of its journey, transmitting a single tone every 10 seconds. Once on the ground, it will beep five times every 30 seconds, relaying its signals to Earth via an older NASA spacecraft called Mars Global Surveyor.

Then, three weeks later, Spirit's sister act Opportunity will make the same hazardous descent. Journalists have talked of a "race" to find life on Mars. In fact, Beagle is the only lander overtly designed to dig below the surface and "sniff" for the chemical signature of life on Mars.

But it can only search where it lands. Spirit and Opportunity are roving robot geologists, each about the size of a golf cart, with stereoscopic cameras at around human eye level, and robotic arms that could grind below the weathered surface of the Martian rocks.

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