Thursday, May 17, 2012

LROC: Multiple Flow Lobes

Multiple flow lobes on the northern interior slope of Furnerius A. Field of view 756 meters, LROC Narrow Angle Camera (NAC) observation M187848982R, LRO orbit 12747, March 31, 2012. Sunlight is from northeast, resolution 0.63 meters. View the 1200 x 1200 pixel LROC Featured Image, released May 17, 2012, HERE [NASA/GSFC/Arizona State University].

Hiroyuki Sato
LROC News System

Today's Featured Image highlights granular flows on the northern wall of Furnerius A crater (11.21 km in diameter), located between Mare Fecunditatis and the South Pole-Aitken basin. At the bottom of the image, a diagonal boundary delineates between the coarse blocky crater floor (relatively bright) and the still coarsely textured, but relatively darker surface, which is part of the sloping crater wall. From the top of the image extend a number of relatively bright granular flows. At the end of each flow, the flow lobe is visible against the darker, coarsely textured crater wall. Notice that the sunlight is from the right side, thus each flow unit is positive relief (not negative relief) on the top of preexisted slope.

Foreshortened contextual view of the Featured Image detailed within the 4.1 kilometer-across field of view swept up in LROC NAC frame M187848932R, March 31, 2012 [NASA/GSFC/Arizona State University].
These granular flow features are commonly observed inside the fresh crater walls on the Moon. Little by little slope failures degrade the steep walls, which enlarge the apparent diameters of the craters, as well as create shallower crater floors. Over long periods of time, small impacts also destroy any sharp relief features, and someday Furnerius A will be transformed into a crater like Furnerius C (left side crater in the image below). Since the Moon's surface has no water or wind weathering (erosion), the Moon is the best natural museum to learn about the long term evolution of crater forms.

Surrounding area of Furnerius A crater in WAC monochrome mosaic (100 m/pix). Image center is 33.49°S, 59.03°E. The locations of full NAC frame (blue box) and the area highlighted in the LROC Featured Image released May 17, 2012 (yellow arrow) are indicated [NASA/GSFC/Arizona State University].
Nearly the same field of view at a higher angle of incidence, perhaps a day after local sunrise (inclination angle 69.65°), reveals more relief, and with the addition of data derived from the LROC WAC Digital Terrain Model, Furnerius A is seen as being on the edge of Furnerius proper to the southeast. LROC Wide Angle Camera (WAC) observation M177251343 (604nm), LRO orbit 11257, November 30, 2011; resolution 69.7 meters from 51 kilometers [NASA/GSFC/Arizona State University].
Explore the beautiful flow lobes in the full NAC frame yourself! 

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