Ground operations began Monday at the Phoenix landing site at Mars' north pole, with the latest images from the robotic lander showing a bizarre, checkerboard landscape apparently shaped by the movement of ice lying only inches beneath the surface.
Employing a "follow the water" philosophy, NASA's Phoenix spacecraft has gone to the pole to search for carbon-containing organic molecules that could indicate Mars' potential as a home for some forms of life.
The first images beamed back to Earth show a complex of polygonal features bordered by narrow troughs. At first glance, they don't appear particularly gripping. Some observers have likened the scene to a lumpy parking lot.
"The pictures may look a little bleak but the science can be fascinating," said Peter Smith of the University of Arizona, the mission's principal scientist.
"This is just like the active surface you see in the Arctic," he said from NASA's Jet Propulsion Laboratory in La Canada Flintridge, which is managing the mission.
On Earth, such features are formed by the thawing and refreezing of water, which cause the surface to expand and contract, something like a sheet of brownies pulled from the oven at the wrong time.
If the ice on Mars does thaw, it could provide a liquid medium for life -- not necessarily higher life forms but possibly rudimentary ones, such as bacteria.
A new batch of pictures received Monday night showed one glitch on the craft. A protective sheath covering its 7.7-foot-long robotic arm failed to deploy properly and is inhibiting one of the arm's joints.
Deborah Bass, a JPL deputy project specialist, called the issue more of an inconvenience than a problem. Phoenix's controllers will attempt today to wriggle the arm free before attempting to extend it Wednesday.
"This is not that big a deal," Bass said. "We're feeling incredibly confident" about the health of the lander and its capacity to do its job.
Phoenix landed on Mars on Sunday evening after a 296-day, 422-million-mile journey. The 7-foot-tall, 904-pound craft, built by Lockheed Martin Space Systems Co., made a near-perfect touchdown.
The landing was the first since the arrival in 2004 of NASA's twin rovers, Spirit and Opportunity, and the first soft landing -- using thrusters and a parachute instead of the rovers' protective air bag system -- since the Viking missions 32 years ago.
NASA Administrator Michael Griffin said the landing showed how the mission team was the "the most expert of the expert."
The $420-million mission is expected to last 90 days or, in the words of Barry Goldstein, the Phoenix project manager at JPL, "until Mars freezes over."
Phoenix landed in the spring season, but in winter the lander will be enveloped by a thick coating of carbon dioxide ice, which will probably kill its electronics and prevent its solar panels from gathering even the minimal amount of sunlight available.
Pictures taken by a mast camera that came down shortly after the landing showed that one of the lander's 3-foot pads had dug about 4 inches into the topsoil.
That made the scientific team even more optimistic that Phoenix would be able to dig down to the ice level.
"I think we won't have any trouble at all," Smith said.
The average temperature in the region is thought to be about minus 27 degrees Fahrenheit. That's far below freezing, but there are conditions that could allow the ice to melt and refreeze.
JPL also released an image of Phoenix descending through the Martian atmosphere, dangling from its parachute. The picture was taken by the high-resolution camera on the Mars Reconnaissance Orbiter, one of three spacecraft circling the Red Planet.
It was the first time in history one spacecraft has been able to take a picture of another during a landing on an alien planet, a feat some Phoenix team members doubted could be achieved.
"When this was first proposed, I was very skeptical," Goldstein said.
It was just one accomplishment for a mission that, so far at least, has been marked by one glittering achievement after another, starting with a picture-perfect landing that one NASA manager compared to hitting a hole in one in Australia after teeing off in Washington.
The single glitch was the failure of the sheath, known as a bio-barrier, to fully deploy around the robotic arm. That sheath was installed to prevent the spacecraft from contaminating Mars with bacteria from Earth.
Officials said that the sheath's failure to deploy would not affect the operation of the arm.
Also Monday, mission managers sent the first command to the orbiting Mars Odyssey spacecraft, which relayed it to Phoenix.
"We've achieved the first major goal of the mission," Smith said.
Communications with Phoenix are being relayed through Odyssey and the Mars Reconnaissance Orbiter because Phoenix does not carry an antenna capable of direct communications with Earth.
Phoenix will be the first spacecraft to sample the water of another planet. Because the ice layer is expected to be as hard as concrete, Phoenix carries a special drilling tool to break it into shards for analysis.
Phoenix carries eight tiny ovens to heat the ice and soil samples to test for organic molecules.