Tuesday, April 22, 2014

Impact on an old and steep slope

Unnamed crater ejecta, within Dante C, field of view 1728 meters, centered on 28.463°N, 182.491°E, downslope is to the lower-right.  From LROC NAC observation M1137707212L, LRO orbit 19746, October 29, 2013; angle of incidence 57.33° resolution 1.44 meters from 143.84 km [NASA/GSFC/Arizona State University].
Hiroyuki Sato
LROC News System

Dante C is a ~54 km diameter crater, located in the central farside highlands. In the northwestern portion of the crater floor, there is an unnamed crater (about 3 km in diameter) with a spectacular diffuse asymmetric ejecta pattern (see next WAC no-shadow context view, right side).

The uphill side (upper-left) shows a distinctive wavy pattern of ridges and grooves (seen in the opening picture) within about 3 km of the rim.

Probably due to the background slope (Dante C crater wall, downslope is to the lower-right), the ejecta hit the ground and stopped in a shorter distance than on the downhill side, leaving partially wrinkled edges in the ejecta deposits.

Wider, 6.14 km-wide field of view, context for area of interest at far upper center, left, from LROC NAC mosaic M1153033874RL, LRO orbit 21901, April 25, 2014; incidence angle 58.14° resolution 1.45 meters from 146.22 km over 29.17°N, 182.54°E [NASA/GSFC/Arizona State University].
33.1 km-wide field of view from LROC Wide Angle Camera monochrome [604 nm] mosaic, swept up over three sequential orbital passes, LRO orbits 11135-11137, November 20, 2011; average incidence angle 60° at 57 meters resolution, from 43.84 km [NASA/GSFC/Arizona State University].
Context view of Dante C crater and surroundings, LROC WAC monochrome mosaic overlayed with DTM with GLD100 at left, and WAC normalized reflectance at right (100 m/pix). Image centered on 28.57014°N, 182.63728°E, field of view 62 km. The location of area shown at high-resolution in LROC Featured Image released April 22, 2014 designated with arrow [NASA/GSFC/Arizona State University].
97 km-wide field of view from the same LROC Wide Angle Camera monochrome [604 nm] mosaic, swept up over three sequential orbital passes, LRO orbits 11135-11137, November 20, 2011 [NASA/GSFC/Arizona State University].
The downhill side shows a smooth surface without the wavy pattern, implying that the thin layer of ejecta spread out homogeneously on the downslope. Also, the thickness of the ejecta itself might have been asymmetric due to the local slope. The uphill slope can interrupt ejecta's lateral motion, leaving unique ridges and grooves, another example of the range of crater forms found on the Moon.

Craters like Dante C disappear under low-angle sunlight. Fresh rays from much younger craters, like Jackson, and even a young crater on its northwest interior, outshine such a very ancient crater. View the full size 1000 px original gif file, HERE [NASA/GSFC/Arizona State University].
Explore the asymmetric ejecta with clear wave patterns in full NAC frame, HERE and in LROC QuickMap, HERE.

Related Posts:
Impact Art
Bright and Dark Ejecta
Dynamic Textures
Ejecta Patterns
Lassell D Ejecta
In the Wake of Giordano Bruno
Ground Hugging Ejecta

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