PARIS -- Europe's Mars Express satellite successfully entered Mars orbit today, setting the stage for up to four years of study of Mars' atmosphere, surface and subsurface to look for water and signs of current or past life.
The fate of the small Beagle-2 lander, however, remained unknown. An initial overhead pass by NASA's Odyssey satellite failed to pick up a Beagle-2 signal, and mission managers were unable to confirm whether the lander survived its descent through Mars' atmosphere and planned landing on the surface.
"We obviously have concerns about Beagle-2," European Space Agency Science Director David Southwood said. "We need everybody just to be patient. One should not write it off at this point."
Beagle-2 has been viewed as potentially the most fragile portion of the Mars Express mission. Once the lander separated from Mars Express on Dec. 19, it has been on its own and without means of communication. Built on a shoestring given the challenges of its mission, Beagle-2 carries no backup systems whatsoever.
A failure of any one of its operating systems -- the heat shield to protect its descent into the atmosphere, the deployment of its parachutes or its air bags, the opening of its solar arrays - would spell the end of Beagle-2.
Odyssey will make several more overhead passes in the coming days to listen for signs of life from Beagle-2. A British observatory later today (10:45 p.m. GMT, 5:45 p.m. EST) will also attempt to pick up Beagle-2 signals directly to see whether it has survived the frigid Martian night with enough battery power to deploy its instruments.
Mission managers said a failure to detect a signal tonight, early in the morning Mars time, would force them to begin to confront the prospect that Beagle-2 did not survive.
But for the European Space Agency's Esoc mission control center in Darmstadt, Germany, the word that Mars Express' main engine burn successfully put the satellite into orbit around Mars brought clear relief.
"This is the most extraordinary Christmas present I have ever had," European Space Agency Director-General Jean-Jacques Dordain said. "Now that we have received signals from Mars Express telling us it is in orbit, there is no more reason for doubts and fears. As for Beagle-2, we still have some time."
Mars Express was launched June 2 and traveled a total of about 400 million kilometers before reaching its destination. It is Europe's first solo mission to another planet and will take its place alongside NASA spacecraft in a long-term study of Mars.
Michael McKay, flight operations director, said in a telephone interview today that on Dec. 30 a series of Mars Express motor firings will gradually bring the satellite's orbit down closer to Mars, with the operational orbit expected to be reached by mid-January.
It will take several months to calibrate all seven Mars Express instruments, which notably include a radar altimeter that is designed to penetrate up to several kilometers beneath the surface to search for underground water.
"All our systems are looking green," McKay said, referring to the control center's panel showing Mars Express subsystems. "We are ecstatic."
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