Tuesday, May 13, 2014

A splendid oblique view of Larmor Q

LROC NAC view of the south wall and rim of splendiferous Larmor Q crater, looking obliquely east-to-west; LROC NAC oblique mosaic M174081337LR, LRO orbit 10788, October 24, 2011; 44.93° incidence angle, resolution roughly 2.3 meters, spacecraft and camera suite slewed 67° from orbital nadir, 59.44 km over 28.84°N, 211.72°E [NASA/GSFC/Arizona State University].
J. Stopar
LROC News System

Larmor Q (28.674°N, 176.32°E) is sub-circular crater, whose  23 km diameter is measured north to south and 19 km measured east to west.

But Larmor Q is not just another stunning crater; it is also scientifically interesting.  Oblique images, like the one below, provide a unique vantage point that can help with geologic interpretation.

Oblique view (reduced for web-browsing) of Larmor Q crater, looking east-to-west. The crater is wider in the north-south direction than in the east-west direction. Click for larger image [NASA/GSFC/Arizona State University].
One of the most obvious features of Larmor Q is the large accumulation of slumped wall materials inside the crater. This crater is a transitional morphology between smaller simple craters like this one, HERE, and larger, complex craters like Tycho or Copernicus.

The crater Giordano Bruno (21 km in diameter) is another example of a transitional crater. Wall slumping in transitional craters affects the final crater shape. When the northern wall of Larmor Q failed, the northern rim crest of the crater moved outward, contributing to the larger crater diameter in the north-south direction.

Prominent features of Larmor Q include slumped wall material and impact melt deposits; located at 176.313°E, 28.634°N [NASA/GSFC/Arizona State University].
This oblique image of Larmor Q is also useful for studying the distribution of impact melt, which, in turn, can tell us how impact melt is generated and interacts with the forming crater. In Larmor Q, most of the impact melt rock is located inside the crater opposite the largest slumped materials.

View of impact melt deposits inside Larmor Q. The melt has splashed up the southern wall (left) and ponded in the floor of the crater (center of image)[NASA/GSFC/Arizona State University].
Flows of impact melt on the rim of Larmor Q crater now solidified into lobate deposits [NASA/GSFC/Arizona State University].
There are also several relatively small deposits (flows) of impact melt rock on the crater rim. Because the largest concentration of impact melt occurs opposite the largest slumped materials, we infer that the melt “splashed” up on the southern wall primarily as a result of the slumped material impinging on the crater floor.

LROC Wide Angle Camera (WAC) image of the 18.3 km diameter crater Larmor Q. Slumping of the crater walls has not yet covered all the impact melt on its floor. LROC WAC monochrome (604 nm) observation M136389155C, LRO orbit 5233, August 14, 2010; 54.83° angle of incidence, resolution 82 meters from 58.4 km [NASA/GSFC/Arizona State University].
NASA ILIADS application simulated orbital view (not too dissimilar to the oblique perspective of the LROC Featured Image released May 13, 2014) shows the region of the lunar farside highland terrain between Larmor Q (23 x 19 km; 28.674°N, 176.32°E, bottom center) and Mare Moscoviense (275 km; 27.28°N, 148.1°E), perhaps the most immediately eye-catching feature of the Moon's opposing hemisphere, 750 km away and 1000 meters higher in average elevation above global mean. LROC WAC 100 meter global mosaic imagery applied to LRO LOLA laser altimeter-based digital elevation model [NASA/MSFC].
The full resolution oblique view of Larmor Q crater contains more fascinating clues of the impact cratering process, HERE.

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