Thursday, August 8, 2013


Debris flows converge at the bottom of a youthful crater on the northern frontier of the Moscoviense basin (32.660°S; 143.668°E). LROC Narrow Angle Camera (NAC) frame M1107331321R, spacecraft orbit 15474, November 12, 2012; 62.63° incidence, 1.45 meters resolution from 145.44 km. Field of view approximately 1.4 km across [NASA/GSFC/Arizona State University].
James Ashley
LROC News System

Small crater floors are places where slopes facing different compass directions (azimuths) naturally approach each other.

Steep, recently formed slopes will often produce debris flows that migrate part way or completely to the floor.

The resulting zones of debris convergence can present interesting juxtapositions of coarse and fine deposits with variable light and shadow effects. On an airless body like the Moon, the patterns are frequently striking, and make for studies in artistic composition. The play of sunlight on these surfaces often create some surprising textural patterns and relationships.

Context for the LROC Featured Image within a 7 km field of view [NASA/GSFC/Arizona State University].
This small, unnamed farside crater in the lunar highlands presents a nice example. High-reflectance ejecta in the WAC context image shows it to be the result of a relatively recent impact. Mass wasting events have generated debris flows that have different textures by the time they come to rest at or near the crater floor. Their different slopes produce different angles of illumination and different intensities of reflection.

M187306990RL-NASA/GSFC/Arizona State University
Roughly 9.2 km-wide field of view from LROC NAC mosaic M187306990LR, LRO orbit 12672, March 25, 2012; 31.65° angle of incidence, resolution 105 cm per pixel from 161.18 km over 32.67°E, 143.77°E [NASA/GSFC/Arizona State University].
 Slightly less than 40 km-wide field of view from LROC Wide Angle Camera frame M167260236CE, orbit 9783, 56.55° angle of incidence, 67.4 meters per pixel resolution from 50.4 km [NASA/GSFC/Arizona State University].
There are also examples of impact melt visible in the debris, best seen in the full NAC frame just south of the Featured Image boundary. What clues would you look for to help distinguish impact melt from fine-grained debris flows?

The bright ejecta from the small crater (arrow) contrasts sharply from its far more 'optically mature' surroundings, allowing the eye to easily pick area of interest in small scale albedo maps and this segment of the LROC GLD100 mosaic showing the crater's location with respect to Mare Moscoviense [NASA/GSFC/Arizona State University].
Explore additional details in the full NAC frame HERE.

Similar Featured Image posts have been presented as "Diversity," "Complicated Crater," and "Rubble Pile on Fresh Crater Floor."

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