Sol 43 update on Curiosity from USGS Scientist Ken Herkenhoff: Transits19 September 2012
A couple of transits of Mars' moon across the face of the sun were observed by Mastcam. These are similar to solar eclipses on Earth, but because the Martian moons are so much smaller than Earth's moon, they do not completely block the sun. But they are still fun to watch and scientifically useful, as they allow the position of the moons to be determined and their orbits to be precisely updated. The rate of change of the moon's orbits is affected by the interior structure of Mars, so in a way the transits are geophysical observations.
I was SOWG Chair for Sol 43 planning, and I was busy because it was an ambitious plan: ChemCam characterization in morning, followed by a ~30 meter drive toward a dark boulder that may become the target of close-up investigation using the arm. On the morning of Sol 44, the rover will wake up early to look for frost or fog before dawn, then take a big Mastcam panorama toward the northwest while the lighting is good.