Ejecta Patterns

A portion of an unnamed, young crater's ejecta deposit. LROC NAC M188557336R. Image center is 3.972°N, 311.942°E, image width is 960 meters. Direction of the ejecta flow is from right to left [NASA/GSFC/Arizona State University].

Today's Featured Image highlights a portion of a very fresh ejecta deposit. The source crater is an unnamed crater about 1.2 km in diameter, located within Oceanus Procellarum. As seen in the NAC context view below, the higher reflectance ejecta spreads radially from the crater, and in some regions may have formed interference patterns that look a bit like fish scales. The opening image focuses on a typical portion showing this geometric pattern. 

NAC M188557336R context view at reduced resolution. Image width is about 5.4 km. Yellow box shows approximate location of the opening image [NASA/GSFC/Arisona State University].

In the vacuum of space, the ejected materials experience no atmospheric drag, and thus no fluid dynamic instabilities driven by such an interaction occur. How then was this sparse/dense ejecta pattern formed? The advancing ejecta curtain probably already had internal density contrasts that produced greater or lesser collision frequencies among the admixed rock fragments. Portions having regular density at intervals with portions have irregular density might have formed this odd, scaly pattern. 

Context view of the unnamed young crater and the surrounding area in LROC WAC monochrome mosaic (100 m/pix). Image center is 3.96°N, 311.94°E. NAC footprint (blue box) and the location of opening image (yellow arrow) are indicated [NASA/GSFC/Arisona State University].

Explore the exotic patterns of this young crater ejecta in full NAC frame yourself!

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Published by Hiroyuki Sato on 21 February 2013