Mars Exploration Rover Update - April 4, 200

http://marsrovers.jpl.nasa.gov/mission/status.html

SPIRIT UPDATE: Spirit Slipping on New Terrain - sol 436-441,
April 04, 2005

Spirit is heading toward the summit of "Husband Hill." The rover has
been making slow progress recently due to slippage on new, sandy
terrain, but it is persevering to reach the target. The rover team
performed image brightness tests with the navigation camera to assess
how late in the sol Spirit can use sunlight for imaging.

Sol-by-sol summaries:

Sol 436 (March 25, 2005):
Spirit took panoramic camera images of areas dubbed "Cottontail" and
"Blanket." The rover also completed a 24-meter (79-foot) drive.

Sol 437:
Spirit took some post-drive images and performed other remote sensing.
It took a sky survey, measured the opacity of the atmosphere, and
looked
for dust devils.

Sol 438:
Spirit did a lot of remote sensing on sol 438, taking three surveys of
the sky, measuring the opacity of the atmosphere, searching for dust
devils, and looking for clouds.

Sol 439:
Spirit drove 3 meters (10 feet). It also conducted an image brightness
test with its navigation camera. The rovers can't take images when it
is
too late in the sol since they use the natural light from the Sun to
illuminate features on Mars. The rover team experimented with taking
pictures later and later this sol. Currently, the rover team does not
usually take pictures after long drives, but if the images taken later
in the sol come back clear and useful, then the team will start
commanding the rover to take images later in the sol, after drives.

Sol 440:
Spirit completed a 1.7-meter (5.7-foot) drive.

Sol 441 (March 31, 2005):
The rover completed a 2.28-meter (7.48-foot) drive. On the new terrain
that Spirit has reached, the rover slipped 45 percent on an 11-degree
slope. In the past, when Spirit was on an 11-degree slope, the rover
did
not slip as much, but this terrain is much sandier than previous
terrain
Spirit has driven on. The rover used to have a slip limit at 40
percent,
so the rover would automatically shut off if it slipped that much. The
rover team increased the allowable slippage to 60 percent to enable the
rover to progress and move forward.