Tuesday, April 16, 2013

Crater chain near Rima T Mayer

A small, rather unique crater chain, or catena, near Rima T Mayer, a geologically and observationally interesting region northwest of the central near side, between Copernicus and Kepler. LROC Narrow Angle Camera (NAC) M181373663R, a 2.6 km field of view captured at 1.29 meters per pixel resolution from 128.61 kilometers in spacecraft orbit 11842, January 16, 2012; angle of incidence 64.29° [NASA/GSFC/Arizona State University].
Sarah Braden
LROC News System

What sound do impacts make when they hit the lunar surface? If you were an astronaut standing on the lunar surface, you probably would not hear anything even if you were nearby since the lunar surface is a near-vacuum! However, you might feel the rumble of the impact through your boots perhaps giving you enough time to duck behind a nearby boulder. Today's Featured Image shows part of a ~3 km long crater chain, located at 13.360°N, 328.807°E.

The irregular shape of the crater rims and tapered appearance suggests that these are not primary but rather secondary craters, formed from material ejected from a larger primary impact.

LROC Wide Angle Camera (WAC) context image of the area surrounding the crater chain (located inside the white box). The sinuous rille Rima T Mayer winds its way through the region (denoted by white arrows). Image field of view 58 km across [NASA/GSFC/Arizona State University].
Secondary craters form many of the crater chains on the Moon, but not all. The term crater chain, or catena, describes any set of craters in a linear array. Crater chains can be formed not only by secondary craters but also by volcanic collapse (associated with graben) or primary impacts from a string of smaller objects which was observed during the Comet Shoemaker-Levy 9 impact with Jupiter.

A slightly closer look at the same region in "pushed" LROC WAC photography shows the catena bisects a contact zone between an effusive dome structure and the mare material of the surrounding area. Illustration from "New Pyroclasts identified using LROC data," February 18, 2011. LROC WAC observation M117691527ME (689 nm), orbit 2478, January 9, 2010 [NASA/GSFC/Arizona State University].
Can you find other areas with evidence of secondary crater ejecta in the full LROC NAC, HERE?

Related Images:
Tres Amicis
Four of a Kind in Catena Davy
Stream of Secondary Craters
Chain of Secondary Craters in Mare Orientale
New Pyroclasts identified using LROC data

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