Mars Lander's Robot Arm Fully Unpacked

TUCSON, Ariz. – Scientists with the Phoenix Mars mission have completed releasing the spacecraft's robotic arm from its travel restraints.

Now, on day four on Mars, they're getting ready for the crucial instrument to start moving around in preparation for its digging experiments in arctic soil and ice.

Matt Robinson of NASA'S Jet Propulsion Laboratory is in charge of software for the robotic arm. He said Thursday the mission team will only partially extend the arm at first to allow its camera to peek beneath the Phoenix Mars Lander's platform.

Scientists want to ensure it is fully stable on the ground and not resting on a rock that could tilt the lander once the arm is fully extended.

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The Phoenix lander, which arrived on Mars on Sunday, is in excellent shape, said project manager Barry Goldstein Wednesday. He said the communications glitch was only a blip in the robot's three-month exploration of the planet's northern arctic region.

The outage occurred Tuesday in one of two NASA satellites circling Mars when a radio shut off before it could relay commands to the lander to get the 8-foot arm moving, Goldstein said.

The robotic arm was folded on the lander's science deck to protect it from the vibrations of the launch and landing.

Before Phoenix could flex its arm, it had to rotate its wrist to release the latches on its forearm and elbow and "move it out in a staircase fashion" to remove its protective sleeve, said robotic arm manager Bob Bonitz of NASA's Jet Propulsion Laboratory.

Phoenix's arm will eventually dig into the soil surrounding it, seeking ice believed to be within inches to a foot below the surface. It's part of the effort to study whether the site could have supported primitive life.

The robotic arm has four joints in all — two at the shoulder to allow it to move side to side as well as up and down, an elbow and a wrist, which allows it to move its crucial scoop and digging device.

Phoenix has delighted scientists with the first-ever peek of the planet's northern arctic region since its landing Sunday onto relatively flat terrain containing few rocks. Twin rovers have been operating near the Martian equator since 2004.

Texas A&M University's Mark Lemmon, who is in charge of the lander's camera, said scientists are still investigating geometric patterns in the surface likely caused by the expansion and contraction of underground ice.

Some areas immediately surrounding the lander would be designated a no-digging "natural preserve," Lemmon said.

A few features on nearby terrain have been given such nicknames as Humpty Dumpty and Sleepy Hollow, he said.

The $420 million mission is led by University of Arizona, Tucson, and managed by JPL.