Though ESA's five-day, space manhunt for Beagle 2, involving massive radio telescopes in England and the United States, has failed to detect a signal, scientists aren't giving up hope. They say their best chance of tracking the small probe will come after Jan. 4, when the Mars Express spacecraft enters into an orbit that will bring it within 200-250 kilometers of the planet’s surface.

Mars Express is the only craft that has been designed specifically to communicate with the Beagle 2, providing the best chance of establishing contact with the stray probe. But first, Mars Express has to be moved from its higher orbit around the equator to a lower polar orbit -- a maneuver that will require the firing of its engine on Dec. 30.

"These key maneuvers will allow us to get even closer to Mars," said Michael McKay, ESA’s Mars Express flight director. "They will not only allow us more frequent ‘overflights’ of the Beagle 2 landing area, but also ensure the beginning of the orbiter’s science mission. As Mars Express is the planned main communication partner of Beagle 2, the chances of obtaining a signal strongly increase."

Listening for a pulse

The team of scientists behind the Beagle aren’t fretting just yet. They’ve also deployed massive telescopes around the world to trace Beagle’s signal, including an extremely powerful radio telescope at California’s Stanford University that is capable of detecting radio emissions from the lander’s microchip. But sifting through the volume of data the telescope delivers will take weeks, like finding a needle in a haystack.

"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."

Once Mars Express enters into polar orbit, its high-resolution stereo camera can take close-up shots with enough detail to identify the lander’s parachutes and gas bags on the Martian surface. Beagle 2 is also supposed to increase its radio signals around the time Mars Express enters into the correct orbit.

"We need to get Beagle 2 into a period when it can broadcast for a much longer period," said Colin Pillinger, the scientist at Britain’s Open University who created the lander. "This will happen around Jan. 4 after the spacecraft has experienced a sufficient number of communication failures to switch to automatic transmission mode."

'Tiger Team' probes worst-case scenarios

Meanwhile, scientists in Britain have put together a "tiger team" at the British National Space Center to run through different problem scenarios on a functioning mock-up of the lander to see if and how they can be solved.

"We've pulled out a number of specialists into a think-tank," said Alan Wells, a Beagle team scientist. "These guys are looking at what information we're getting so far from the contact attempts, analyzing that data and looking at recovery options we can pursue. What we're doing is looking at any possibility where Beagle 2 is still functioning and we're not able to communicate with it for some reason."

Scientists initially thought the clock might have damaged as it hurdled through the Martian atmosphere, but they have now abandoned that theory in favor of new possibilities.

The first is that Beagle may have landed in a canyon, and that its position is obscuring the lander's signal. A software glitch in Beagle's clock could be causing it to transmit its signal at the wrong times so that telescopes on Earth miss picking it up. Another theory is that the Beagle's oyster-like shell has failed to unfold. And although the European Space Agency hasn’t given up on the Beagle yet, scientists in Europe have begun to broach the possibility that it didn’t survive the landing.

"We’ve always recognized that Beagle 2 was a high-risk project," said Lord Sainsbury, Britain’s science minister. "We must in the future resist the temptation only to do low-risk projects. Long term, we need to be working with the European Space Agency to ensure that in some form there is a Beagle 3."

But before any plans for Beagle 3 can be laid on the table, scientists need to find out what happened to Beagle 2. ESA’s Southwood is still optimistic the spacecraft can be found.

"I certainly haven't written Beagle off, none of the team has," he said. "We believe Beagle is on the surface and the mother, Mars Express, is very anxious to get in touch with her baby again."