Water on this curiosity picture

Check this out! Upper right corner of this image here:

http://mars.jpl.nasa.gov/msl-raw-images/proj/msl/redops/ods/surface/sol/00151/opgs/edr/ncam/NRA_410903087EDR_F0051916NCAM00352M_.JPG

Is this half-frozen water? :shock: :shock: :shock:

yep interesting contrast - and indeed looks like some form of liquid that the rover has dislodged.

But if it was water the rover would have left some tracks? and is it likely that the surface temperature is lower than the ground temperature

wonder what it is?