The May 22, 2013 Featured Image post showed a portion of an unnamed concentric crater located in the Apollo Basin. Today’s Featured Image is a spectacular oblique (57° from vertical) view of that same crater.
Lunar geologists find craters useful in investigations because they tell so much about the geological history of the Moon. Craters reveal structural properties below their surface and the relative ages of the surfaces where they formed. How can looking at a hole in the ground be so insightful? Combining imaging with numerical modeling and laboratory experiments, we can test how different structural properties beneath craters affect their shape and size, and even derive information about the direction of the impactor that formed the crater. Crater counting lets us estimate how long a surface has been exposed; more craters indicate an older surface. While insightful, these techniques do not conclusively describe the formation mechanism for all observed crater shapes. That is the case for concentric craters such as the one in today’s post, an unnamed 11.5 km concentric crater located in the Apollo Basin, centered at 30.757°S, 205.923°E. Concentric craters have an inner rim whose formation mechanism is not yet entirely understood, but the concentric mounds may indicate that there is a discontinuity, such as layers with different strengths, in the subsurface excavated by the impact.
Craters are beautiful landscapes depicting the violent impact history of the Moon, but are also a reminder of how human ingenuity can unravel the formation mechanisms of geological features on other worlds. As is the case for concentric craters, some of nature’s mysteries require on-site human and robotic investigations to fully understand them.
Check out the full resolution NAC below.
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