[meteorite-list] Mars Rover Opportunity Update: December 16, 2015 - January 3, 2016

[Ron Baalke]

OPPORTUNITY UPDATE:  Opportunity Welcomes Winter Solstice -
sols 4229-4246, December 16, 2015-January 03, 2016

Opportunity is inside 'Marathon Valley' on the west rim of Endeavour Crater. 
The rover is positioned on steep, north-facing slopes for improved solar 
array energy production.

The winter solstice occurred on Sol 4246 (Jan. 3, 2016), although solar 
insolation already started to improve. The near-term objective is to position 
the rover to be able to grind a high-value surface target with the Rock 
Abrasion Tool (RAT). This target may hold some of the clues as to the 
origin of the clay spectral signature detected in Marathon Valley.

On Sol 4229 (Dec. 16, 2015), Opportunity bumped about 14 inches (35 centimeters) 
to set up for an extended in-situ (contact) science campaign through the 
holiday season. Over the holiday period, Opportunity proceeded to use 
the robotic arm to collect Microscopic Imager (MI) mosaics of the surface 
targets as well as place the Alpha Particle X-ray Spectrometer (APXS) 
for surface elemental analysis. Winter power levels and late Odyssey passes 
made planning difficult with some sols being used as recharge days.

On Sol 4234 (Dec. 22, 2015), Opportunity was able to use the RAT to brush 
the surface target 'Pvt. John Potts.' This was followed with more MI mosaics 
and APXS measurements. On Sol 4244 (Jan. 1, 2016), the RAT was used again, 
this time to grind (1 millimeter) into the surface target. More MI mosaics 
and APXS elemental analysis of the ground target followed.

As of Sol 4246 (Jan. 3, 2016), the solar array energy production was 449 
watt-hours with an atmospheric opacity (Tau) of 0.414 and an improved 
solar array dust factor of 0.658.

Total odometry is 26.50 miles (42.65 kilometers), more than a marathon.