Wednesday, October 19, 2011

LROC: Bedrock atop central peaks of Theophilus

The sun casts long shadows on the central peak of Theophilus crater. Oblique from LROC Featured Image, October 18, 2011; Narrow Angle Camera (NAC) observation M135019514R, LRO orbit 5031, July 29, 2010; field of view about 280 meters. See the full 700 meter field of view in the LROC Featured Image HERE [NASA/GSFC/Arizona State University].
Drew Enns
LROC News System

Theophilus is a large 102 km diameter crater located at 11.4°S, 26.4°E.

Like many other complex craters, it has terraced walls, a flat floor, and a large central peak. The Theophilus central peak even has abundant exposed rocks at its summit! 

The impact process excavates material from depth, and the deepest material forms the central peak. This exposed rock must then be lunar crustal rock weathering out of the central peak!

Full width of the LROC NAC frame (M135019514R) shows the deep lunar crust that was almost instantly upthrust to the 1400 meter height of the four central peaks of Theophilus by a catastrophic Eratosthenian Age impact between around 3.2 to 1.1 billion years ago [NASA/GSFC/Arizona State University].
A 25 km-wide LROC Wide Angle Camera (WAC) monochrome (643 nm) mosaic of observations swept up during three orbital passes showing the dramatic central peaks of Theophilus in a local mid-afternoon illumination, February 1, 2010; average resolution 56 meters per pixel. The area near the summit of one of the four central peak spotlighted by the LROC Narrow Angle Camera is indicated in the reduced mosaic below. The software used to stitch together the panorama mosaic from three sessions, an hour and a half apart, left behind a few artifacts. [NASA/GSFC/Arizona State University].
Future explorers may sample these rocks from talus fields at the base of the peak. Since they are from the deepest material now exposed in the crater, valuable information about the three dimensional nature of the crust would be readily at hand.

Context image showing the location of the area spotlighted as the LROC Featured Image, October 18, 2010, a hefty portion of the Moon's original crust elevated to 1400 meters higher than the floor of Theophilus crater by rebounding forces at the time of the original impact (located in the yellow box. Image field of view is 140 kilometers. LROC WAC monochrome (643 nm) mosaic from three consecutive orbital passes, February 1, 2010. View the LROC WAC context image that originally accompanied their Featured Image HERE  [NASA/GSFC/Arizona State University].

Are there more exposed rocks in the full NAC frame?

Related Posts:
Central Peak of Bullialdus Crater
At the Top of the Avalanche
Tycho Central Peak Spectacular!

Deep lunar nearside crater Theophilus (11.4°S, 26.4°E) as seen in a still frame from NHK television's HDTV camera on-board Japan's groundbreaking first lunar orbiter SELENE-1 (Kaguya) in 2008. See the full width (at lower resolution) HERE [JAXA/NHK/SELENE].

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