Today's Featured Image displays a portion of eastern rim of Flamsteed P crater, located in southern Oceanus Procellarum. The rough and darker right side corresponds to the rim slope, and the brighter and smoother area to the left is the younger mare basalt. Flamsteed P's interior was mostly filled by mare basalts and all that remains are portions of its rim showing as discontinuous ridges (see WAC context image below).
In terms of local timeline of events (geochronology), following the formation of Flamsteed P, mare basalt flooded its interior and exterior. Later a small crater (110 m diameter) formed just at the boundary between the mare and crater rim (bottom of today's Featured Image). This small crater is half covered by the older rim unit. Does this make sense? Even though the small crater is much younger than the Flamsteed P rim it is buried by rim materials that slid downhill after the crater formed. What cause the regolith to move? Perhaps moonquakes generated by internal stresses or nearby impact events. Or perhaps a slower process of downhil creep caused by thermal cycling of the regolith (soil). We have much to learn about the Moon - the next frontier!
The topographic color was produced as a by-product of stereo analysis of the WAC global dataset. Producing the global Digital Elevation Model (DEM) is a big job being led by LROC team members at the German Aerospace Center (DLR; English version) in Berlin.
Explore the boundary of mare basalts by viewing the full NAC frame!
Posted by Hiroyuki Sato on April 05, 2011 09:00.