Mars Exploration Rover Update - March 14, 2005

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SPIRIT UPDATE: High Winds Make Spirit Full of Energy - sol 416-421,
March 14, 2005
Spirit is in good health and is successfully using a new version of
flight software. After completing an investigation of a rock dubbed
"Watchtower," Spirit is returning to a soil area of interest informally
labeled "Paso Robles." Tau, a measure of how much sunlight cannot
penetrate the atmosphere, rose to a high of 1.5 on the afternoon of sol
418, but the opacity of the atmosphere has since dropped off. Energy
output from Spirit's solar panels is up as of sol 420, indicating that
some cleaning of dust off of the solar arrays may have occurred
As Spirit and Opportunity are the first solar-powered vehicles on the
surface of Mars during the dust storm season, this is a learning
experience. There are likely large transient dust storm events that
reduce solar energy due to dust deposition on the solar arrays and
blocking some sunshine, but also may sometimes raise energy levels by
cleaning dust from arrays, possibly by winds associated with dust
storms. The impact on other rover systems, such as cameras, will also
closely monitored.
Sol-by-sol summaries:
On sol 416, which ended on March 5, 2005, Spirit awoke around 4 a.m.
local solar time at Gusev Crater to start its alpha particle X-ray
spectrometer and use a communication window with the Mars Odyssey
orbiter passing overhead. Later, Spirit did a three-hour grind with its
rock abrasion tool, digging about 7 millimeters (0.27 inch) into
Watchtower. Spirit then placed the alpha particle X-ray spectrometer
into the rock abrasion tool hole for an overnight integration.
On sol 417, Spirit gathered images of the rock abrasion tool hole with
the microscopic imager, performed a variety of remote-sensing
observations, and then placed the Mossbauer spectrometer in the hole
an overnight integration.
On sol 418, Spirit continued the Mossbauer spectrometer integration and
acquired remote-sensing data. A regional dust storm caused tau the
a new high if 1.5 in the afternoon and reduced solar energy for the day
to roughly 350 watt-hours. After the dust storm, Spirit's front
hazard-avoidance camera showed signs of dust contamination similar to
that seen earlier on Opportunity's rear hazard-avoidance camera.
On sol 419, Spirit completed remote-sensing observations, including
imaging to learn more about the contamination on the front
hazard-avoidance camera. Slight mottling is visible in images from both
eyes of the stereo camera. It is not enough to affect use of the camera
or to have any direct impact on rover operations, but understanding how
it happened might help the rover team minimize future occurrences.
Spirit then moved backwards about 1 meter (3 feet) from Watchtower to
use mast-mounted instruments for observing that rock. After that, it
starting to drive toward the soil target Paso Robles. However, the
planned 14-meter (46-foot) drive ended after just 1 meter (3 feet) due
to a software sequence ordering issue.
On sol 420, Spirit drove 7 meters (23 feet) of a planned 14 meters (46
feet) towards Paso Robles. The drive ended prematurely due to a problem
in visual odometry, which is part of the software that enables the
to drive autonomously. Energy output from the solar array rose
dramatically, to more than 600 watt-hours. In part, this is due to a
favorable northerly tilt of the rover, which points the solar arrays
toward the Sun. Also, tau is going back down, but it is possible that
some cleaning event occurred that reduced the dust on the solar panels.
On sol 421, Spirit drove 7 meters (23 feet) and arrived close to the
Paso Robles target. Spirit still needs another few meters to get into
position to use the instruments on its robotic arm. Solar energy
continues to be very high: more than 700 watt-hours. The last time
Spirit had this much energy was around sol 80!
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