Wednesday, July 27, 2011

LROC: Rümker E - Melt and more melt

Southwestern edge of Rümker E crater floor, LROC Narrow Angle Camera (NAC) observation M122591558L, LRO orbit 3200, March 7, 2010; resolution 0.5 meter per pixel, field of view 500 meters with an illumination incidence angle of 43° from south-west. View the full-size LROC Featured Image HERE [NASA/GSFC/Arizona State University].

Hiroyuki Sato
LROC News System

The floor of Rümker E crater exhibits a variety of beautifully preserved impact melt features.

The platy surface, partially submerged boulders and flows are an invitation to explorers!

The edges of the floor are sharply overlayed by debris avalanches from the cavity slopes. How did the flows seen on the left form? Are they impact melt or later debris flows?

Full view of the Rümker E crater floor at the full field of view width of about 2.5 km seen in LROC NAC M122591558L. The square corresponds to the LROC Featured Image released July 27, 2011. See the full-sized context image HERE [NASA/GSFC/Arizona State University].

Crater shapes are changing with time little by little, by slope failures inside the cavity, isostatic rebound, and magma intrusions (depending on the crater size). Debris flows in Rümker E will continue to mask the melt-covered floor, eventually the whole area. There are lots of degraded craters on the Moon showing no interior melt deposits, but they may be there now buried waiting for future astronauts to uncover.

Impact melts are especially interesting to geologists because they are clocks. The melting resets the internal radiometric clock so even a small sample provides the means to date the moment the impact occurred.

LROC Wide Angle Camera (WAC) 100 meter/pixel monochrome (643 nm) mosaic of the region of interest, near Rümker E crater (lower right), including the northern Oceanus Procellarum landmark volcanic Rümker formation immediately to the north-by-northwest. Mosaic stitched from four sequential orbital observation opportunities swept up on January 10, 2010 [NASA/GSFC/Arizona State University].

Explore Rümker E floor in the full NAC frame by yourself!

Related posts:
Das crater
Anomalous mounds on the King crater floor
Mounds in a melt pond
Impact melt features in Tycho crater's floor

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