February 10, 2013

Hidden Roughness

left: Apollo AS17-M- 0307 image from ASU Apollo Image Atlas, and right LRO mosaic from LRO QuickMap

The Moon is dead, but it keeps changing before our eyes. That is what makes it so fascinating.
When I came across this marvelous terminator image from the Apollo 17 Metric Camera, I real-
ized that the lava surface near Dawes was far more tortuous than it appears on most of the other
images I'd seen. The LRO mosaic on the right has a relatively high Sun angle and it depicts an
apparently relatively homogenous mare surface. But under nearly grazing lighting the surface is
rough everywhere, and broad undulations become visible - see north and west of Beketov. With
only a limited amount of the surface covered by such low Sun images it is impossible to under-
stand the origins of the undulations. Perhaps if we had similar images for the entire Moon we
would discover a new level of surface processes. I keep hoping that such a mosaic will come
from the Lunar Reconnaissance Orbiter Camera team.

Chuck Wood

Related Links
Rükl plate 25
21st Century Atlas charts 8 & B5.

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