Image: Robotic arm
A view from the Opportunity rover's front hazard avoidance camera shows its robotic arm extended over Martian soil. The end of the arm bristles with instruments.

Scientists fixed a glitch that froze the robotic arm of the Opportunity rover and then prepared to dig a narrow trench in the Martian soil, NASA said Saturday.

Scientists hoped the patch of soil, dubbed "Hematite Slope," would prove to be rich in the iron-bearing mineral that typically forms in water.

On Friday, exploration was temporarily delayed after Opportunity failed to properly stow its robotic arm. Engineers sent instructions to the rover that repaired the problem, mission manager Jim Erickson said.

Robot smarter than scientists
The glitch occurred when the rover realized scientists had sent instructions for its robotic arm to perform what could have been an unsafe movement. The rover stopped with its robotic arm extended until scientists revised the commands.

"The rover is sometimes smarter than we are," said Erickson. "The trick is to catch these on the ground and resequence them correctly before we send them up. We believe we're going to be able to prevent that class of problem in the future."

Scientists want Opportunity to dig 4 inches (10 centimeters) or so into the soil, using one of its front wheels to excavate the narrow trench. They hope Opportunity will find minerals that could help reveal whether ancient Mars was wet enough for a long enough time to support life.

Such analysis is a key goal of the mission of Opportunity and its twin rover, Spirit, on the other side of the planet.

Looking at Stone Council and Mimi
NASA planned for Spirit to spend much of the weekend inspecting two rocks, nicknamed "Stone Council" and "Mimi," and the surrounding soil before resuming its trip toward a crater about 1,100 feet away (335 meters).

Image: Mimi
The flaky rock at the center of this image taken by Spirit is known as Mimi. Scientists say one possibility is that it was once a dune that was cemented into flaky layers, a process that sometimes involves the action of water.
"Spirit is still moving out, but it's stopping to smell the roses along the way," Erickson said.

Scientists were considering how to increase Spirit's driving distance from 85 feet (26 meters) a day to 100 feet (30 meters) a day. One option was to use the panoramic camera to provide images so scientists on the ground could see up to 165 feet (50 meters) ahead.

"Our navigational cameras aren't really good enough to pick out a good route in advance when we're talking about 30, 40 or 50 meters," Erickson said.

© 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.


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