OPPORTUNITY UPDATE: Still Grinding After All These Years - sol 1389-1395, Feb 06

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

OPPORTUNITY UPDATE: Still Grinding After All These Years -
sol 1389-1395, Feb 06, 2008:

With only about a month remaining before Opportunity’s fourth
anniversary (in Earth years) of Mars exploration, NASA’s robotic
geologist is still grinding into the surface of rocks to unlock the
secrets of their interior chemistry. Meanwhile, fall arrived in the
southern hemisphere of Mars on Dec. 9, 2007, Opportunity’s 1,378th
Martian day, or sol, of exploration of the Red Planet. Ten days later,
Earth made its closest approach to Mars, coming within 88 million
kilometers (54.8 million miles).

Opportunity used the rock abrasion tool to bore a shallow hole into a
rock target known as “Lyell_1” and then spent about 70 hours
integrating
data about iron minerals inside the rock using the Moessbauer
spectrometer.

During integration with the Moessbauer spectrometer, the rover adds
measurements in a running total, sort of like exposing film. A longer
exposure builds up the light areas, improves contrast, and results in
a
clearer, more distinct image, whereas a shorter exposure produces an
image that is somewhat underexposed, darker, and less well defined.
Similarly, longer integrations with the Moessbauer spectrometer yield
more distinct signatures of iron content and the chemical state of the
iron.

At the end of the Moessbauer campaign, Opportunity re-positioned the
robotic arm to take images of the grind hole. The rover’s handlers
postponed acquiring images until after the holidays. On sol 1395 (Dec.
27, 2007), Opportunity acquired a mosaic of microscopic images of the
ground rock surface before placing the alpha-particle X-ray
spectrometer
on a new rock target known as “Lyell_2.” The resulting 2-by-2-by-14
mosaic was a collection of microscopic images arranged side-by-side
like
the four windowpanes in a square window. Within each of the four
panes,
Opportunity took 14 microscopic images at various distances from the
rock surface. Because the microscopic imager is a fixed-focus camera,
this process of acquiring images at different heights enables the
rover
to obtain images with different focal points. Because engineers don’t
always know where the best focus point will be, they start high, move
closer, and finish low. Ideally, the middle pictures will be perfectly
focused and higher and lower images will be slightly fuzzy.

Usually, the rover takes a stack of five microscopic images. This
time,
however, Opportunity took one image up high, one image down low, and
four images at each of the three intervening heights. The multiple
images will allow image processing experts to determine a digital
average and cancel out unwanted data, known as “noise” to engineers.

In addition to studies using the Moessbauer and alpha-particle X-ray
spectrometers, Opportunity conducted routine atmospheric tests,
acquiring so-called Tau measurements of atmospheric dust with the
panoramic camera. The rover took additional panoramic camera images of
the immediate area using multiple filters. By combining images taken
with different filters, engineers can create both true- and false-
color
views.

Following is a typical sol in the life of the Opportunity rover: Each
Martian day is divided into blocks of activities separated by naps.
The
first block, known as the “engineering block,” begins when sunlight is
strongest and temperatures are warmest. This is when the rover
performs
the bulk of the day’s activities, including drives and housekeeping
activities such as arm movements. After this, Opportunity takes a
“nap”
with no activities to allow the early afternoon sun to recharge the
rover batteries.

In the late afternoon, the rover wakes up for a communication session
with the orbiting Odyssey spacecraft. This period is known as the
“Odyssey block” and involves “pre-Odyssey,” “Odyssey,” and
“post-Odyssey” activities. Afterward, the rover naps or goes into a
deep
sleep. During deep sleep, the rover shuts off power to almost
everything
on board. The following morning, the rover may wake up autonomously if
there is enough solar power – this time period is called “solar array
wakeup.” During this block, engineers usually schedule one or two
small
activities, followed by another nap to recharge the batteries. If
there
isn’t enough solar power, the rover omits the solar array wakeup
block.

Finally, the rover wakes up for the daily X-band communication session
with Earth. This is known as the “AM block.” At this time, the rover
generally does imaging activities in parallel with communications.
This
block ends with a so-called “handover” from the previous sol’s plan to
the new sol’s plan.

Sol-by-sol summary:

In addition to morning uplinks directly from Earth via the rover’s
high-gain antenna, evening downlinks to Earth via the Odyssey orbiter
at
UHF frequencies, and panoramic camera measurements of atmospheric
opacity caused by dust, Opportunity completed the following
activities:

Sol 1389 (Dec. 20, 2007): Opportunity acquired panoramic camera images
of the turret, placed the Moessbauer spectrometer on Lyell_1, and
acquired approximately 12 hours worth of data with the instrument.

Sol 1390: In the morning, Opportunity surveyed the horizon with the
panoramic camera. The rover restarted the Moessbauer spectrometer and
spent approximately 12 hours integrating data with the instrument.
Opportunity acquired a 13-by-1 mosaic of panoramic camera images of
Lyell_1 and used the navigation camera to pinpoint the Sun’s location
in
support of the upcoming Mars Science Laboratory mission. The rover
went
into a mini-deep sleep.

Sol 1391: Upon solar array wakeup, Opportunity monitored atmospheric
dust and then monitored dust on the rover mast assembly. The rover
restarted the Moessbauer spectrometer and spent about 12 hours
integrating data from Lyell_1 with the instrument. Opportunity
acquired
a 5-by-1 tier of navigation camera images and, after communicating
with
Odyssey, went into a mini-deep sleep.

Sol 1392: Opportunity restarted the Moessbauer spectrometer
integration
of Lyell_1 and spent about 12 hours collecting data with the
instrument.
Opportunity acquired a 4-by-1 mosaic of images looking downslope at a
target known as “Gilbert.” The rover went into a mini-deep sleep.

Sol 1393: Upon solar array wakeup, Opportunity measured atmospheric
dust
and acquired Part 1 of a panoramic camera mosaic of foreground images.
Opportunity spent another 12 hours engaged in Moessbauer spectrometer
analysis of Lyell_1 and, after communicating with Odyssey, went into a
mini-deep sleep.

Sol 1394: Following solar array wakeup, Opportunity monitored
atmospheric dust and acquired Part 2 of the panoramic camera mosaic of
foreground images. The rover conducted a survey at high Sun with the
panoramic camera, restarted the Moesbauer spectrometer, and spent
about
12 hours integrating data from the instrument. The rover went into a
mini-deep sleep.

Sol 1395 (Dec. 27, 2007): Upon solar array wakeup, Opportunity
measured
atmospheric dust and scanned the sky for clouds with the navigation
camera. Opportunity swung the robotic arm out of the way of the hazard
avoidance camera, acquired full-color images of Lyell_1 using all 13
filters of the panoramic camera, and swung the robotic arm back into
place over Lyell_1. The rover acquired stereo microscopic images of
Lyell_1 and placed the alpha-particle X-ray spectrometer on Lyell_2.
After communicating with Odyssey, Opportunity spent approximately 17
hours integrating Moessbauer spectrometer data from Lyell_2. The
following morning, after communicating with Odyssey, Opportunity was
scheduled to measure atmospheric dust and take thumbnail images of the
sky with the panoramic camera.

Odometry:

As of sol 1395 (Dec. 27, 2007), Opportunity’s total odometry remained
at
11,591.21 meters (7.2 miles).