Tuesday, June 11, 2013

Slope Resurfacing

Southeastern wall of Jansen U crater. LROC Narrow Angle Camera (NAC) observation M188028576R, spacecraft orbit 12773 April 2, 2012; 18.45° angle of incidence, resolution 0.98 meters from 120.28 km, 1182.3 meter-wide field of view centered on 11.926°N, 32.306°E (Downslope toward upper left, north at top) [NASA/GSFC/Arizona State University].
Hiroyuki Sato
LROC News Service

Today's Featured Image highlights the wall of Jansen U crater, located at the northeast section of Mare Tranquillitatis. Jansen U is a 3.28 km diameter crater with a teardrop shaped cavity, and likely originated from a low angled oblique impact (see next NAC context image).

The high reflectance area includes many boulders is the crater wall. The low reflectance area in the lower right of the image, which includes a smaller crater (~130 m in diameter), is the rim and shallowly sloping ejecta blanket. The upper left corner of the image, which is covered by low reflectance materials (but not as low as the background surface), corresponds to the crater floor.

Jansen U crater in NAC context image, center on 11.955°N, 32.304°E, field of view about 4 km. The Featured Image corresponds to the field of view outlined by the white box [NASA/GSFC/Arizona State University].
Jansen U crater has an eye-catching appearance due its ovoid shape and brilliant contrast between the low reflectance floor higher reflectance crater walls. Since no indication of impact melt is seen on the crater floor (e.g. fractures or viscous flow features), the floor is likely covered by post impact in-filling materials. Little by little space weathering produces the mature regolith everywhere on the surface, while the slope failure slumps mature material away continuously. These mass wasting and weathering processes often result in striking albedo patterns. 

Jansen U and surrounding Mare Tranquillitatis in LROC WAC monochrome mosaic (100 m/pix), centered on  6.15°N, 16.17°E. The NAC footprint (blue box) and the location of the field of view in the LROC Featured Image (yellow arrow) are indicated [NASA/GSFC/Arizona State University].
Explore Jansen U crater, contrasting reflectance patterns of the wall and the floor in the full NAC frame, HERE.

Related Posts:
Downhill Creep or Flow?
Leathery vs smooth surface
Slope failure near Aratus crater
Crater Covered With Boulders!
Bright ridge near Mons Hansteen
Multiple Flow Lobes

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