Thursday, March 22, 2012

LROC: Ryder Spectacular

Boulders, slopes and shadows inside Ryder Crater (43.86°S, 143.28°E). Distance across base of shadow is about 1800 meters LROC Narrow Angle Camera (NAC) M176670797 orbit 11171, November 23, 2011; spacecraft slewed -61.8° 51.37 kilometers over 43.94°S, 147.87°E. View the larger Featured Image HERE [NASA/GSFC/Arizona State University].
Mark Robinson
Principal Investigator
Lunar Reconnaissance Orbiter Camera (LROC)
Arizona State University

Ryder crater is rather oddly shaped; is it two craters or one?

It is 17 kilometers in the long direction and 13 kilometers in its shortest dimension. The western floor of the crater is about 1500 meters below the western rim while the eastern rim is 3000 meters above that same floor. The eastern shelf, seen in today's Featured Image, is 5000 meters above the western rim!  How did Ryder crater end up in this shape?

LROC WAC stereo derived contours on Wide Angle Camera (WAC) mosaic, contour interval 500 meters. Ryder crater is at center, characterized by bright, rays. View the slightly larger LROC context image HERE [NASA/GSFC/Arizona State University].
It formed on a steep slope, which certainly contributes to the odd morphology, but it may have formed as the result of an oblique impact. But why does it resemble a snowman? Was it formed by the impact of a split asteroid? As with most complicated geologic problems, the real answer is likely some combination of hypotheses.

LROC NAC oblique image (east to west) of Ryder crater (shrunk 20x from original); illuminated edge of interior shelf is a little over 3 kilometers across. Today's Featured Image is a full resolution view of this shelf [NASA/GSFC/Arizona State University].

Ryder crater is named after Graham Ryder, a planetary geologist (petrologist) who made many important contributions to our understanding of the Moon. It is fitting to remember him this week as the annual Lunar and Planetary Science Conference unfolds. Many new results concerning the Moon, Mars, Mercury, and other bodies in the Solar System are being presented.

The WAC stereo dataset gives an awesome look at global topography. However, to really unravel the history of Ryder crater scientists need topographic maps with 10 meter contours, or better. As the LRO mission progresses Ryder crater will be imaged in stereo by the NAC, providing scientists with a higher resolution look, and thus the opportunity to model how this unique crater formed.

In the meantime, enjoy the view of Ryder crater, HERE.

Revisit some earlier LROC
Oblique views of the Moon

Tycho crater
Aristarchus crater
Hadley rille
Vertregt J crater
Aitken crater
Bhabha crater

Tight view of the impressive variety of boulders on the bench formation in Ryder, from 64.4 km overhead, illuminated from the east an an incidence angle of 61.48° LROC NAC M167268729L, orbit 9784, August 6, 2011. Resolution 0.664 meters in a field of view 385 meters across [NASA/GSFC/Arizona State University].

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