JPL efforts appear to be working

Nov 21, 2009 08:40 GMT  ·  By
Spirit is seen here "stretching" its robotic arm, before the first drive commands were uploaded to its computer earlier this week
   Spirit is seen here "stretching" its robotic arm, before the first drive commands were uploaded to its computer earlier this week

For the first time in more than six months, the rover Spirit took a tiny step towards freeing itself from the grasp of the loose patch of soil known as Troy. The powder-like sand was covered by a thin crust, which gave way as the robot was climbing a 12-degree slope, which led to a formation known as Home Plate. Engineers at the Jet Propulsion Laboratory (JPL), a NASA facility at the California Institute of Technology (Caltech), decided not to move the rover forward, considering that it was already stuck up to its hubcaps in the ground.

After months of testing – which saw the use of a Spirit replica in a JPL sandbox – mission controllers finally came up with a plan of extricating the rover, which they set into motion this Tuesday. However, the roll stopped just seconds after it began, as the robot's sensors detected a tilt that exceeded the narrow limits set in place by the JPL team. A second drive attempt, with revised limits, took place on Thursday, after drivers uploaded a new set of commands to Spirit's onboard computer. The team waited for the results with anticipation.

When they came in, they could breathe in relief. The machine appears to have moved a tiny bit from its original spot, which brings new hope that, with hard work, it will be freed altogether. JPL MER project manager John Callas says that the entire process could take weeks or even months. Once a small success is registered, the team will halt the motion, and use the rover's cameras to look around and underneath it. These investigations are required to ensure that they are not driving Spirit even further in its predicament, Space reports.

During the Thursday drive attempt, Spirit was given a command to spin its wheel for a length of time that would on usual terrain equal it driving forward for about 8.2 feet, or 2.5 meters. The center of the robot was however budged by only an inch, or about 1.2 centimeters forward, and 7 millimeters to the left. The movement also sank the rover into Troy by about 4 millimeters. The second command that was uploaded to the computer, which told Spirit to spin its wheels for a second time, was not executed, because the machine had a limit of moving just 0.4 inches, and that limit was exceeded with the first drive.

At this point, NASA experts and JPL engineers are looking for the new data, in an attempt to determine the next course of action. A future drive command will most likely be uploaded to Spirit over the next few days. For more details, keep an eye on this space.

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