After a 23-meter drive on Sol 1611, MSL again ended up in an area with many bedrock blocks partly covered by dark sand.  We're planning two sols today to get a head start on planning for the holiday weekend, with the first sol strategically planned to allow the "touch and go" option.  But there's a ridge about 30 meters ahead that we can't see over, and we would like to be able to drive up onto it on Sol 1612 to allow a drive past it to be planned this weekend.  There isn't enough time before the "decisional" telecommunications opportunity to fit both contact science and a 30-meter drive into the plan, so we had to pick one of these two options.  Based on images taken from orbit and by the rover, lots of bedrock is exposed at the crest of the ridge 30 meters away, so we picked the longer drive at the expense of contact science today, hoping that the rover will be in a better place for contact science this weekend.  Before the drive, ChemCam and Right Mastcam will observe a bright/dark boundary on a block at the left side of the image above (dubbed "Frenchville"), and Right Mastcam will acquire a 2x2 mosaic of another block named "Third Lake."  After the drive, we're planning fewer images to support weekend planning because the expected downlink data volume is much less than usual.  We therefore spent more time than usual carefully prioritizing the post-drive images for downlink, and may not receive all of the data we need to plan contact science and a drive this weekend. 

Later in the afternoon of Sol 1612, ChemCam will again use AEGIS to autonomously select a LIBS target and acquire a 3x3 set of chemical measurements.  The REMS software upgrade went well, so REMS environmental monitoring is being planned again today!  On Sol 1613, ChemCam will acquire passive calibration data, and Navcam will search for dust devils and clouds.  Finally, the rover will sleep overnight in preparation for what we hope will be a busy weekend plan.  The issues described above made for a challenging day for me as SOWG Chair!