Wednesday, April 18, 2012

LROC: Dark Impact Melt Sheet

A portion of southern rim of unnamed immature crater. The interior of the crater is in the top half of the image. LROC Narrow Angle Camera (NAC) observation M169764515R, orbit 10152, September 4, 2011; a 500 meter wide field of view on 18.652°N, 121.299°E resolution 0.47 meters from 38.57 kilometers. View the full size LROC Featured Image HERE [NASA/GSFC/Arizona State University].
Hiroyuki Sato

Today's Featured Image explores the southern rim of an unnamed crater ~2 km in diameter, located near Olcott crater. The distinctly asymmetric ejecta shape (seen in the WAC image below) suggests that this crater resulted from an oblique impact. The impactor arrived traveling from the NNE to the SSW, thus the southern side of this crater is downrange.

In the image above, the upper portion (brighter area exposing high reflectance materials) corresponds to the inner slope of the crater cavity. The rim of this crater is covered by low reflectance material. The features of this dark material, such as the flow lobe at image bottom, fragmented pattern at the upper boundaries, and the cracks inside the dark areas, suggest that the material is impact melt.

LROC QuickMap zoom of the area of interest, at 16 meters per pixel resolution [NASA/GSFC/Arizona State University].
The entire southern half of this crater rim is covered by impact melt, suggesting that the impact melts were splashed downrange (relative to the direction of the original impact) and covered much of the southern rim. Can you imagine the dynamic the nature of this impact event?

LROC Wide Angle Camera (WAC) monochrome mosaic around the unnamed immature crater, centered on 18.53°N, 121.30°E. Blue rectangle designates NAC M169764515R footprint and the yellow area marks the location of the area highlighted in the LROC Featured Image released April 18, 2012. View the full size context image HERE [NASA/GSFC/Arizona State University].
You can see the whole rim of this oblique impact crater in full NAC frame HERE.

Related Posts:
Asymmetric Ejecta
Timocharis Crater
Slice of Mare
Nature's Art
Crash or Coincidence?

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