[meteorite-list] Mars Exploration Rovers Update - January 27, 2006

[Ron Baalke]

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

SPIRIT UPDATE: Spirit Nears 'Home Plate' - sol 730-735, 
Jan 27, 2006:

Spirit continues to make progress toward "Home Plate," a conspicuous 
circular feature scientists hope to investigate before the Martian 
winter, in search of layered rock outcrops that may provide 
additional information about the geology of the "Columbia Hills." 
During the past week, the rover has driven nearly 100 meters 
(328 feet), and has still had time to do some targeted remote 
sensing. Spirit is currently just less than 170 meters (560 
feet) from Home Plate.

During the past week, engineers noticed some anomalies in dynamic 
braking on two of the steering motors, similar to previous events 
on Spirit. Based on analysis and testing, they were able to 
continue the drive without incident.

Sol-by-sol summaries:

Sols 730 and 731 (Jan. 22 and 23, 2006): The weekend plan included 
a 10.8-meter (35.4-foot) drive to the crest of "Lorre Ridge." 
Spirit acquired targeted pre-drive and post-drive images. The 
rover spent most of Sunday recharging the battery to allow a 
longer drive on Monday.

Sol 732: Spirit drove 40 meters (131 feet), using a combination 
of commanded and autonomous navigation along with a parallel 
obstacle-check sequence to keep from getting too close to potential 
hazards. The rover acquired a pre-drive image of a target called 
"FuYi." After the drive, the panoramic camera and navigation 
camera acquired forward-looking mosaics. The next morning, Spirit 
acquired rear-looking images with the navigation camera and 
forward-looking mosaics with the panoramic camera using two 
more filters.

Sol 733: Spirit completed an automous drive of approximately 
40 meters (131 feet). Just before beginning autonomous navigation, 
Spirit experienced a dynamic brake error in the left front and 
right rear steering actuators, at which point engineers halted 
the drive.

On the surface, this appeared to be similar to dynamic brake 
anomalies experienced on sols 265 (Oct. 1, 2004) and 277 (Oct. 
13, 2004), which involved the right front and left rear steering 
motors. Analysis and testing at the time indicated that the 
problem was consistent with a delayed contact on the status 
relay. The rover engineering team sent a command to ignore the 
relay status, and since then, the rover has driven (with all 
steering motors enabled) without incident.

In the meantime, the team determined that it was safe to continue 
driving, but without using the left front and right rear steering 
motors.

Sol 734: Spirit drove approximately 9 meters (30 feet) autonomously. 
Engineers conducted the same diagnostic tests they ran following 
the sol 265 incident in the testbed, to verify that the procedures 
worked with the current flight software. While awaiting dynamic 
brake diagnostics, they disabled Spirit's left front and right 
rear steering motors and allowed Spirit to drive only where 
they could clearly see the surrounding terrain and it was not 
necessary to steer around any obstacles.

Sol 735 (Jan. 27, 2006): Planned activities included a short, 
autonomous drive with the left front and right rear steering 
motors disabled, following a short diagnostic activity to characterize 
the behavior of the dynamic brakes and the dynamic brake relay 
switch.

Odometry:

As of sol 735, Spirit's total odometry was 6,279.01 meters (3.9 
miles).

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OPPORTUNITY UPDATE: Opportunity Takes Microscopic Images, Collaborates 
with European Mars Mission - sol 708-714, Jan 27, 2006:

Opportunity remains healthy following another busy week. The 
main activity of the week was taking microscopic images of a 
feature nicknamed "Lower Overgaard." The science team identified 
individual, high-priority targets of interest, nicknamed "Scotch," 
"Bourbon," and "Branchwater." After the microscopic imager successfully 
acquired images of "Scotch," one of the actuator motors on Opportunity's 
robotic arm (Joint 2, which controls elevation) stalled less 
than 1 milliradian from its final position. Engineers performed 
diagnostic activities on Joint 2 over the weekend and determined 
that the actuator appeared to function properly. Opportunity 
resumed work with the microscopic imager but was unsuccessful 
because of a stall on the Joint 1 actuator. Engineers increased 
the electrical resistance and Opportunity again began acquiring 
microscopic images.

This past week, Opportunity also supported coordinated observations 
with the European Space Agency's Mars Express spacecraft, using 
the miniature thermal emission spectrometer and panoramic camera, 
and also took images of a transit across the sun by Phobos. 
Science team members next plan to adjust the rover's position 
slightly to conduct microscopic analysis of another target area, 
nicknamed "Upper Overgaard."

Sol-by-sol summaries:

Sol 708 (Jan. 21, 2006): Opportunity took microscopic images 
of a surface target dubbed Scotch on Lower Overgaard. Microscopic 
imaging was successful, but the Joint 2 (elevation) actuator 
motor on the rover's robotic arm stalled less than 1 milliradian 
from its final position.

Sol 709: Opportunity conducted diagnostics of Joint 2 during 
the weekend and acquired images of a Phobos transit.

Sol 710: Opportunity conducted remote science observations and 
supported Mars Express observations using the miniature thermal 
emission spectrometer and panoramic camera.

Sol 711: Opportunity took thumbnail images of the sky and images 
of Mars' albedo (a measure of surface reflectivity) with the 
panoramic camera in support of a coordinated observations by 
Mars Express.

Sol 712: Opportunity took super-high-resolution images of targets 
known as "Loupp" and "Dewey" with the panoramic camera.

Sol 713: As Opportunity began executing a plan to take microscopic 
images of the Bourbon target on Lower Overgaard, a joint on 
the rover's robotic arm (Joint 1, which controls shoulder azimuth) 
stalled, preventing acquisition of the microscopic images.

Sol 714 (Jan. 27, 2006): Opportunity re-acquired some of the 
microscopic images of the target Scotch that were not fully 
in focus when first taken on sol 708 (Jan. 21, 2006).

As of sol 714, Opportunity's total odometry remained at 6504.55 
meters (4.04 miles).