17 years ago
OPPORTUNITY UPDATE: Back to 'Purgatory' - sol 497-502, July 05, 2005:
Opportunity made its way back toward "Purgatory Dune" for a chance to
explore its own tracks. During the drive the rover stopped along the
to study the soil at "North Dune."
Sol 497 (June 16): This was the second sol of a two-sol plan. Today was
dedicated to remote sensing, including panoramic camera usage with 13
filters and stares with the miniature thermal emission spectrometer.
Sol 498: On sol 498, Opportunity deployed its robotic arm to get a
"taste" of the North Dune. The rover did this using both the
imager and the alpha particle X-ray spectrometer. The next sol, the
rover moved slightly back (about 40 centimeters or 1.3 feet) and then
slightly forward (the same distance) in a move designed to place it on
an optimal approach, ready to drive to its destination on Purgatory
Dune. The last sol of this three-sol plan was again spent as a
Sols 501 and 502: Opportunity had been trying to line itself up with
science target by performing arcs. Due to nature of this terrain, it
not been yawing as much as expected so its approach was slightly off.
The team decided to have the rover try a turn in place. Engineers had
been staying away from turning in place because Opportunity has a bad
steering actuator on one wheel, and this makes turning in place more
cumbersome. This turn in place, however, had some advantages because it
was in the right direction and it was a small turn. The rover performed
The turn in place churned up soil in front of Opportunity. This made
immediate area in front of the rover more prone to slippage.
detected excessive slippage (more than 30 percent) when it attempted to
perform the first of two 25-centimeter (9.8-inch) arcs. The visual
odometery system detected that the first arc went only 17.1 centimeters
(6.7 inches). This constituted a 32 percent slip. The engineers had
limited the acceptable amount of slippage to 30 percent, so the rover
was not commanded to perform the second arc. The next sol was a
Sols 503 and 504 (June 22 and 23): The team planned another drive
consisting of three 25-centimeter (9.8-inch) arcs. This drive was
calculated to bring the rover to its destination at Purgatory Dune.