NASA researchers instructed the Phoenix Mars Lander perched near the Red Planet's north pole to unstow its 7.7-foot (2.3-meter) robotic arm in preparation for collecting samples of subsurface ice surrounding the probe, the space agency announced today. Phoenix operators were forced to delay deployment of the arm by one day when the Mars Reconnaissance Orbiter (MRO), which had been relaying transmissions between Phoenix and Earth since the craft landed Sunday, switched off communications unexpectedly.

Phoenix executed preprogrammed backup commands to keep taking photos and monitor the local weather, which MRO relayed to mission controllers yesterday evening after transmissions were reestablished, the agency said.

Unstowing the arm consists of "a series of seven moves, beginning with rotating its wrist to release the forearm from its launch restraint," robotic arm manager Bob Bonitz of NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a statement. "Another series of moves releases the elbow from its launch restraints and moves the elbow from underneath the biobarrier."

Images sent back Monday showed that the elbow joint was still partially wrapped in a protective sheath that was supposed to peel off after landing.