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Of all the perilous situations and technological issues the two Mars rovers dealt with, soft soil wasn’t tops on my list of what might mean the end of roving on Mars. The Spirit rover is stuck in an area of soft sand-like soil, slipping severely during recent attempts to drive, sinking the wheels about halfway into the ground. The rover engineers and scientists has suspended driving Spirit temporarily while studying the ground around the rover and planning simulation tests of driving options with a test rover at NASA’s Jet Propulsion Laboratory, Pasadena, Calif.

“Spirit is in a very difficult situation,” JPL’s John Callas, MER project manager said Monday. “We are proceeding methodically and cautiously. It may be weeks before we try moving Spirit again. Meanwhile, we are using Spirit’s scientific instruments to learn more about the physical properties of the soil that is giving us trouble.”



Spirit has overcome problems with her flash drive, survived climbing and descending Husband Hill with a malfunctioning front wheel, and recently prevailed over problems caused by cosmic ray hit which caused memory problems and “amnesia.” Things were looking up for Spirit as three times in the past month, wind has removed some of the dust accumulated on Spirit’s solar panels, increasing the rover’s capability for generating power.

Spirit has been driving counterclockwise from north to south around a low plateau called “Home Plate” for two months. The rover progressed 122 meters (400 feet) on that route before reaching its current position.

In the past week, the digging-in of Spirit’s wheels has raised concerns that the rover’s belly pan could now be low enough to contact rocks underneath the chassis, which would make getting out of the situation more difficult. The right-front wheel on Spirit stopped working three years ago. Driving with just five powered wheels while dragging or pushing an immobile wheel adds to the challenge of the situation.

“The improved power situation buys us time,” Callas said. “We will use that time to plan the next steps carefully. We know that dust storms could return at any time, although the skies are currently clear.”

Opportunity also had problems with soft soil, running aground in a dune called “Purgatory” back in 2005. Extricating the rover from the dune required more than five weeks of planning, testing, and carefully monitored driving. So, don’t give up hope yet of the engineers figuring out how to get Spirit out of the bind she is in.

We’ll keep you posted.

Source: JPL