TUCSON, Ariz. - Scientists yesterday began releasing the robotic arm on NASA's new Mars spacecraft, one day late because of a radio problem.

The Phoenix lander, which arrived on Mars on Sunday, is in excellent shape, project manager Barry Goldstein said. He said the communications glitch was only a blip in the robot's three-month exploration of Mars' 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 can flex its arm, it must 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, which is managing the $420 million mission.

Controllers sent the instructions yesterday to begin the two-day process. Goldstein said he hoped photos of the partially unfurled arm would be available today.

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 is part of the effort to study whether the site could have supported primitive life.

Phoenix has delighted scientists with the first-ever peek of Mars' northern arctic region since it landed on relatively flat terrain. 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 were still investigating geometric patterns in the surface probably caused by the expansion and contraction of underground ice.

A Delicate Fix - Sooner, the Better

NASA rushed

yesterday

to get a special pump on board the shuttle Discovery to fix a balky toilet at the International Space Station, as the launch countdown got under way.

The space station's

Russian-built toilet has been acting up for the last week. Russian space officials are providing the pump

to launch aboard Discovery on Saturday.

A NASA employee

was

en route from Russia

to Florida with the 11/2-foot-long pump and related hardware, which was packed in a diplomatic pouch and carried onto the commercial jetliner as 35 pounds of hand luggage.

The shuttle flight

is to last 14 days.

- Associated Press

More on the mission

at NASA's Web site via