The Phoenix lander has successfully begun to deploy its robotic arm, which will allow it to dig into the Martian surface and deliver samples of soil and ice to scientific instruments on the lander for analysis.
Commands to the lander are being routed through the Mars Odyssey spacecraft while investigators study an earlier radio glitch with the Mars Reconnaissance Orbiter.
The Phoenix lander touched down in Mars's north polar region on Sunday and quickly started beaming back images of its surroundings.
Now, the lander has slid its robotic arm out of its restraints – two pins that held the arm in place and prevented it from being damaged by vibrations during Phoenix's launch and landing. After freeing itself from the pins, the arm moved itself out from under a sterile wrapping called the biobarrier, which prevented the arm from being contaminated with Earth microbes prior to launch.
NASA sent commands to Phoenix on Wednesday morning PDT (Wednesday afternoon GMT) to unhook the robotic arm. The arm's complete deployment is scheduled to unfold over a period of two days, finishing up on Thursday.
If everything goes well, the arm could start digging by early next week, Phoenix project manager Barry Goldstein of NASA's Jet Propulsion Laboratory in Pasadena, California, US, said in a press briefing on Wednesday. "However we're going to take our time … just to make sure that we do it right."
Unlike the Mars rovers, Phoenix cannot move across the Martian surface. So the Phoenix team is very carefully planning how it will make use of the area within reach of its robotic arm.
The arm deployment was supposed to start on Tuesday, but a glitch prevented the command from reaching Phoenix.
The spacecraft does not communicate with Earth directly, but relies on two spacecraft in orbit around Mars to relay transmissions back and forth.
One of the two spacecraft, NASA's Mars Reconnaissance Orbiter (MRO), failed to transmit commands, including those for arm deployment, during a scheduled communication session with the lander on Tuesday morning. MRO's UHF radio temporarily went into "standby" mode, preventing the commands from reaching Phoenix – a problem engineers are still trying to understand.
Although the UHF radio is now functioning again, NASA plans to rely on the second spacecraft, Mars Odyssey, for relaying commands to Phoenix and transmitting its scientific data back to Earth.
Goldstein says the team knew before Phoenix launched that it could use either MRO or Odyssey for communication. "I know we had a bit of drama yesterday relative to communication, but there never was an issue with Phoenix," he said. "This is a contingency that we had always planned for."
On the bright side, because of the lack of new commands on Tuesday, Phoenix got a head start on assembling a colour panorama of its surroundings. But it will still take two to three weeks to finish and send back to Earth.
Mars Rovers – Mars is full of surprises; learn more in our continually updated special report.
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