Tuesday, October 2, 2012

Secondary melt on the rim of Weiner F

A grooved surface is covered by a sheet of impact melt that has several parallel scarps. Two blocky craters superpose the melt and might be low velocity self-secondaries. LROC Narrow Angle Camera (NAC) frame M1097865095RE, illumination is from the southwest over a field of view 1500 meters across [NASA/GSFC/Arizona State University].
Drew Enns
LROC News System

The low afternoon lighting in today's Featured Image gives the impression that this surface has been sculpted or reshaped somehow.

When an impact occurs, ejecta is thrown out and can scour the exterior rim of the crater.

In this case, the scours are also covered by an impact melt veneer from the same event. Several parallel scarps in the impact melt imply that the melt was emplaced in discrete events.

How could this have happened?

A wider, roughly 4 kilometer-wide view of the interesting melt situated on the ledge within the wider rim of farside highland crater Weiner F [NASA/GSFC/Arizona State University].

LROC Wide Angle Camera (WAC) context image, with the location of the field of view highlighted in the LROC Featured Image released October 2, 2012 marked. Wiener F is located at 40.87° N, 149.91° E, WAC field of view roughly 58 km [NASA/GSFC/Arizona State University].
Impact melt is common in the interior of impact craters, covering the crater floor and crater terraces. Sometimes impact melt also sloshes over the rim of a crater, forming flows. In some cases, the ejected melt forms exterior melt ponds, and in the case of Wiener F an exterior melt pond has formed in an older crater! It is likely the exterior pond formed from several pulses of accumulating impact melt. As the impact melt sloshed around the crater interior, it repeatedly spilled out of the north rim, making several waves on its way down. Similar melt veneers are seen elsewhere on the Moon, such as exterior to King crater.

Explore more of the impact melt at Wiener F crater in the full LROC NAC, HERE

Related Posts:
King Crater's Unusual Melt Pond
Rippled Pond
Anaxagoras Exterior Melt

NASA Lunar Mapping and Modeling Project (LMMP) simulated southwestern perspective over Weiner F helps illustrate the distinctive topography inside and outside the farside highland crater. Is it possible Weiner F resulted from two craters, the second, and more recent offset to the south? [NASA/GSFC/LMMP/Arizona State University].

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