The Mars Express has carried out a major engine burn to sweep it into a polar orbit of the red planet, which will put the spacecraft in prime position to listen for Beagle 2's signal, officials said. The new orbit will carry it more frequently over the Beagle 2 landing site -- a low-lying area near the Martian equator called Isidis Planitia -- improving its chances of receiving a radio transmission from the British lander.

Beagle 2, which presumably touched down on the Martian surface on Christmas Eve, U.S. time, thus far has not made contact despite five straight days of attempts by NASA's Mars Odyssey orbiter and Earth-based radiotelescopes to detect its faint signal.

One theory is Beagle 2 landed in a small, unknown crater that might be blocking its signal. The Mars Express will be swooping as low as 250 miles above the planet's surface and could intercept the Beagle's signal from a different angle than is possible with either the Mars Odyssey or Earth-based instruments.