Old and New

Creepy Slope
Degraded crater wall of Vavilov D. Image center is 1.14°N, 221.536°E, image width is 1440 m, incidence angle is 61°, down slope is to the lower right, M1128031686L  [NASA/GSFC/Arizona State University]. 

Vavilov D is an heavily degraded crater (~96 km in diameter) located between the Orientale basin and Jackson crater. The later formation of Vavilov crater (~99 km in diameter) destroyed the southwestern half of the Vavilov D. Today's opening image highlights the northwestern portion of the Vavilov D wall (see next context image). The relatively smooth textured area in the upper left corresponds to the outside of Vavilov D, and the rest of rough/craggy surface is the interior crater wall slope. 

Context view of Vavilov and Vavilov D craters in LROC WAC monochrome mosaic, overlayed with WAC stereo DTM (GLD100, Scholten et al. [2012]). Image width is 168 km. NAC footprint (blue box) and the location of today's Featured Image (yellow arrow) are indicated [NASA/GSFC/Arizona State University]. 

The two degraded craters (~280 m in diameter) near the middle of the opening image exhibit fascinating overlying smooth features that may have formed as material flowed downslope (arrows). Other morphologic pits/dents on this slope also have similar textures. What we are seeing here are most likely remanants of impact melt that was thrown out of the Vavilov crater. Craggy sloped surfaces with patches of smooth material are often found associated with young impact craters -- formed as impact melt flowed over and around the newly formed crater.

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View From The Other Side

Dark Impact Melt Sheet

Fractured Melt Rock

Young Crater Walls

Published by Hiroyuki Sato on 12 June 2014