Mars lander to get arm-moving order a day late

[May 28, 2008]  TUCSON, Ariz. (AP) -- A day after an orbiter's radio shutdown blocked NASA from telling its newly planted Phoenix Mars lander what to do, orders were on the way to get its robotic arm moving.

A UHF radio on the Mars Reconnaissance orbiter turned off Tuesday, preventing it from relaying the command from NASA to the lander to begin to unfurl its 8-foot robotic arm.

Mission leaders said the incident caused a one-day delay in preparations for getting the spacecraft ready to begin its key scientific experimentation: digging up icy soil samples for testing from its location in Mars' northern arctic region.

Fuk Li, manager of the Mars exploration program for NASA's Jet Propulsion Laboratory in Pasadena, Calif., said the glitch may have resulted from a cosmic ray.

But he and others said the problem was minor, and by the end of the day Tuesday the orbiter's radio had resumed working, relaying Phoenix's images of the Martian landscape back to earth.

The orbiter is one of two circling Mars that is being used in conjunction with the lander's mission. Even with the Mars Reconnaissance orbiter's glitch fixed, officials were sticking with their plan to use the Mars Odyssey, the second orbiter, to relay commands to Phoenix during its morning orbital pass on Wednesday, lab spokeswoman Veronica McGregor said.

The lander has delighted scientists with the first-ever peek of the planet's northern arctic region since it descended onto the Martian landscape Sunday. The terrain where Phoenix settled is relatively flat with polygon-shaped patterns in the ground likely caused by the expansion and contraction of underground ice.

Peter Smith of the University of Arizona, the mission's principal researcher, and his colleague Alfred McEwen, who operates the camera aboard the Mars Reconnaissance Orbiter, said photos taken since the landing show that Phoenix is at the edge of a trough that will make an ideal place for digging.

Smith said plans had called for maneuvers Tuesday to unhook the lander's 8-foot robotic arm from a protective sleeve that held it in place.

The arm is at the heart of the lander's scientific functions during its three-month experiment.

Phoenix will dig into the soil with the arm to reach ice believed to be buried inches to a foot deep. It's part of the effort to study whether the site could have supported primitive life.

Among the things it will look for is whether the ice melted in Mars' history and whether the soil samples contain traces of organic compounds, one of the building blocks of life.

Smith said it would be "hard to conceive" that there isn't ice beneath the lander, given that the landscape is 80 percent ice for the first meter of ground.

Images taken from the Reconnaissance Orbiter's camera showed the lander on the ground with its two solar panels deployed, the spacecraft's jettisoned heat shield and its parachute.

Another series of photos taken by the lander's camera displayed the surrounding landscape and low hills about nine miles away on the horizon.

Weather information gathered by the mission's Canadian Space Agency team showed temperatures ranged between minus 22 degrees and minus 112 degrees Fahrenheit -- "milder than they could be in other places," Smith said.

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On the Net:

Phoenix Mars: http://phoenix.lpl.arizona.edu/

[Associated Press; By ARTHUR H. ROTSTEIN]

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