|A step is situated here, in between a small crater's floor and rim. The crater also displays a high density of boulders on its surface. LROC Narrow Angle Camera (NAC) observation M122700360L, orbit 3216, March 8, 2010; incidence angle 56.8° over a field of view 330 meters across, resolution 0.48 meters from 40.6 km. View the larger LROC Featured Image HERE [NASA/GSFC/Arizona State University].|
LROC News System
Today's Featured Image focuses on an 800 meter crater in northern Oceanus Procellarum, at 48.527°N, 285.939°E.
A crater this small is normally considered a simple crater, but this crater has what looks like a terrace! Terraces are normally found in complex craters, but some simple craters do form benches.
Strength differences in buried rock layers encountered during the impact are probably the cause of such benches. Zooming out and looking at the crater in context may give us a better understanding of whether this is a bench or terrace.
|Context image of the Featured Image, FOV within the box. The image above has been subsampled to 1.5 m/p and the larger image FOV is 1500 meters; LROC NAC M122700360L. View the larger, original context image HERE [NASA/GSFC/Arizona State University].|
The context image reveals that the terrace doesn't circle the entire crater, similar to how complex craters contain multiple unconnected terraces. But the crater is also very blocky, it probably hit a cohesive layer of basalt hidden under a layer of regolith, so maybe it is a bench. Whichever hypothesis is correct, the Moon is definitely not so simple!
|Further context from the NASA ILIADS (LMMP) application. Even as vast an expanse as Oceanus Procellarum has an end, in this case a 2500 meter high boundary between highlands and the Procellarum basin's northwest. The small crater, spotlighted in the LROC Featured Image and designated with a yellow arrow, is situated on mare-inundated terrain roughly 2200 meters below the Moon's mean elevation. Beyond the high mountains (at heights near or only slightly above mean elevation) is the complex heart of the Repsold and Rimae Repsold formation. The floor of Repsold is 500 meters higher than the Procellarum basin floor. LROC Global 100 meter monochrome Wide Angle Camera mosaic overlaid upon LOLA laser altimetry at 128 points per degree (v.2) [NASA/ILIADS/LMMP/GSFC/Arizona State University].|
Terraced Wall in Bürg Crater
Fresh Bench Crater in Oceanus Procellarum