Mars Exploration Rover Mission Status Report
Slow going... that's what's been happening as the five wheels
that still rotate on NASA's Mars Exploration Rover Spirit have been
slipping severely in soft soil during recent attempts to drive. The
result is the sinking of the wheels -- about halfway into the
ground.
The rover team of 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,
project manager for Spirit and its twin rover, Opportunity, 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."
Both Spirit and Opportunity have operated more than five years
longer than their originally planned missions of three months on
Mars and have driven much farther than designed. The rover team has
so far developed ways to cope with various symptoms of aging on
both rovers.
Spirit has been driving counterclockwise from north to south
around a low plateau called "Home Plate" for two months. The rover
progressed 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.
Favorably, three times in the past month, wind has removed some
of the dust accumulated on Spirit's solar panels. This increases
the rover's capability for generating electricity.
"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."
Behavioral problems that Spirit exhibited in early April --
episodes of amnesia, computer resets and failure to wake for
communications sessions -- have not recurred in the past three
weeks, though investigations have yet to diagnose the root
causes.