Thursday, April 19, 2012

LROC: Scalelike Impact Melts

Impact melt sheets on the ejecta deposits beyond the north rim Plato M crater. LROC Narrow Angle Camera (NAC) observation M111700304R, orbit 1595, November 1, 2009. 530 meter field of view centered on 53.276°N, 344.385°E, resolution 0.53 meters and an angle of incidence angle of 60° View the LROC Featured Image HERE [NASA/GSFC/Arizona State University].
Hiroyuki Sato
LROC News System

Today's Featured Image highlights a portion of an ejecta deposit about 1.73 km north from the crater rim of Plato M (7.92 km diameter, located on the north edge of Mare Imbrium).

The texture of the smooth surface and polygonal cracks in this image are the typical characteristics of impact melt (e.g. Herigonius K Impact Melt Flow, Impact melt channel, An Impact Melt Veneer in the Highlands). 

Irregular lines consist of rubble piles that bring the edges of each flow unit into sharp relief. In many cases, the impact melt formed parallel, long tongue-like lobes with a rounded distal edge when it flowed down the slopes formed by the crater's ejecta blanket (e.g. Look at that flow!, Forked Impact Melt Flows at Farside Crater, Outside of Giordano Bruno). But the flow features in this image show short and wide flow units with an irregular distal shape.

Full resolution detail form LROC Wide Angle Camera (WAC) observation M175373431C, orbit 10979, November 8, 2011 (two years after the LROC Featured Image, released April 19, 2012 - the field of view highlighted is designated with the white arrow). Plato M is an unusually bright crater [NASA/GSFC/Arizona State University].
Perhaps a large amount of impact melt was splashed on the ground and flowed only a short distance at relatively high velocity? New high resolution topographic data from the NAC are helping scientists address hypotheses like this one! The large variation of impact melt morphologies seen all over the lunar surface allows us to improve our knowledge of impact cratering processes.

110 kilometers wide WAC monochrome (604nm) mosaic of the ridge immediately west of Plato, between Mare Imbrium and Mare Frigoris with the detail from LROC WAC M175373431C above sectioned off [NASA/GSFC/Arizona State University].
Explore the spectacular flow features around Plato M full NAC frame yourself, HERE. You may find many more intriguing forms!

Related Posts:
Out of the Shadows: Impact Melt Flow at Byrgius A Crater
Impact melt at Necho crater
Rootless impact melt flows
Splash and flow

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