Thursday, September 20, 2012

Top of the landslide at La Pérouse A

The precariously balanced lip of the landslide that, at the opposite end, has 'half-buried' the bright, relatively young crater La Pérouse A, shown in a morphed crop from a large mosaic of the left and right frames from LROC Narrow Angle Camera (NAC) observation M152383525, LRO orbit 7590, February 15, 2011; resolution 0.56 meters from 46.7 km [NASA/GSFC/Arizona State University].
Sarah Braden
LROC News System

When the La Pérouse A impact excavated material from the side of a hill of highland material (1.5 to 2 km taller than the plains to the west), the slope became unstable and collapsed into the crater La Pérouse A. The result is a crater with one rim 920 meters higher than the other.

The Featured Image shows the top of this landslide, now the new rim of La Pérouse A. The landslide material inside the rim is high reflectance, while the undisturbed section of the highland material is relatively darker.

Despite being the same composition, the landslide material is higher reflectance since it is fresh (recently uncovered). Faint lines along the outer edge of the rim are evidence of highland material slumping towards the crater. Collapse features on the Moon often display slump lines, which show where material has fractured and moved downwards, but not completely collapsed. Subsequent impacts or seismic shaking could cause further landslides inside the crater!

A closer look at a 470 meter-wide field of view of the northeast rim of La Pérouse A, LROC Featured Image released September 20, 2012, cropped from LROC NAC frame M152390311L, LRO orbit 7591, February 15, 2011; spacecraft and camera slewed from nadir -8.92° over an angle of incidence of 40.74° Resolution 51 cm per pixel, from 46.56 kilometers [NASA/GSFC/Arizona State University].
The red dashed line shows the crater rim, while the blue dashed line shows the new rim due to the landslide. Reduced scale NAC mosaic M152390311LR, field of view is approximately 4.5 km across [NASA/GSFC/Arizona State University].
Explore the entire NAC mosaic of the crater La Pérouse A, HERE.

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