Phoenix Mars Lander to Flex Robotic Arm
This approximate color of Mars view was obtained on sol 2, May 27, 2008, by the Surface Stereo Imager (SSI) on board the Phoenix lander. The view is toward the northwest, showing polygonal terrain near the lander and out to the horizon.
Credit: NASA/JPL-Caltech/University of Arizona/Texas A&M University.

PASADENA, Calif. — NASA?s Phoenix Mars Lander is set to flex its robotic digging arm for the first time after a one-day delay due to a communications glitch, mission scientists said Wednesday.

Commands to deploy Phoenix?s scoop-tipped robotic arm were uploaded to the probe today, even as scientists pored over the newest images of the spacecraft?s Martian arctic landing site. The new images were beamed to Earth Tuesday evening after the Mars Reconnaissance Orbiter (MRO) switched off its radio antenna earlier the same day for a still unknown reason.

Despite the communication glitch though, Phoenix is doing just fine, mission scientists said at a press briefing.

?The spacecraft is in excellent health, absolutely excellent health,? said Phoenix project manager Barry Goldstein of NASA?s Jet Propulsion Laboratory (JPL).

The craft landed in Vastitas Borealis plains of Mars on Sunday evening to begin its $420-million mission to dig into the rock-hard layers of water ice beneath the Martian soil of the planet?s arctic region. It is designed to test the soil and ice for signs that the water was once liquid, and to see if it could have created a habitable zone for microbial life at some point in the past.

Mission controllers sent Phoenix its first instructions to move its robotic arm this morning. They plan to unstow the arm in stages over the next two days. The arm contains four joints: a ?shoulder? joint that can move the entire arm up and down and from side to side, an ?elbow? joint that also moves up and down and a ?wrist? joint that moves the scoop on the end of the robotic arm.

The first step of unstowing the arm, expected to occur this afternoon, involves moving the scoop towards the arm with the wrist joint, which will release a spring-loaded pin that kept the arm restrained during Phoenix?s August launch and Sunday landing, Goldstein said.

While it seems like a minor movement, ?it?s actually a very critical activity,? said Robert Bonitz, the Phoenix robotic arm manger at JPL.

Mission scientists hope to receive images of the arm?s initial movements during their downlink with NASA?s Mars Odyssey orbiter late tonight.

Because of the MRO antenna glitch, mission controllers are now using Odyssey to communicate with the lander indefinitely. Scientists had planned to use both orbiters throughout the mission, depending on which had a better communication angle during a particular orbit.

?This is a contingency that we?ve always planned for,? Goldstein said.? ?As it stands, we?re in fine shape.?

Goldstein said that digging with the robotic arm is unlikely to start before early next week and that the team is working slowly to make sure each stage is done correctly.

?If [digging] doesn?t get done in the early part of next week, please be patient with us, we are going to do it,? Goldstein said.

Phoenix sent more images of the surrounding Martian terrain on Wednesday morning, including a color image that it took as part of a back-up command sequence it used when it failed to receive instructions from MRO on Tuesday morning.

The image adds to the 360-degree panorama scientists are building from the snapshots taken by Phoenix?s stereo camera. They expect a low-resolution, black-and-white panorama to be completed today, with a higher-resolution, color panorama being completed in a few weeks.

NASA's next Phoenix mission briefing will be broadcast live on NASA TV at 2:00 p.m. EDT (1600 GMT) on Thursday, May 29. Click here for SPACE.com's Phoenix mission coverage and a link to NASA TV.