LROC: Mare Flooded Archimedes

Contact between Archimedes' southwestern interior crater wall (lower left) and floor (upper right). The floor is smooth and relatively flat, compared to the sloped and rough elephant skin-textured crater wall. LROC Narrow Angle Camera (NAC) observation M119883761, LRO orbit 2801 (alt. 39.33 km, res. 0.62 meters per pixel) field of view 800 meters. View the full-sized Featured Image HERE [NASA/GSFC/Arizona State University].

Drew Enns
LROC News System

Archimedes is an 83 km diameter crater located in east Imbrium basin (29.7°N, 356.0°E). Archimedes is notable for its smooth floor, but unlike other craters (e.g., Necho & Copernicus) with smooth floors, Archimedes is flooded with mare basalt. Craters with flooded floors are geologically important as they can establish relative ages of features thanks to the geologic law of superposition.

LROC Wide Angle Camera monochrome mosaic, context image showing Archimedes. The 85 km-wide crater floor appears as smooth as Mare Imbrium to the northwest. Arrow shows location of the LROC NAC Featured Image. Field of view is 130 kilometers, view the full-sized context mosaic HERE [NASA/GSFC/Arizona State University].

A second LROC WAC monochrome (689nm) mosaic swept up over several orbital opportunities on January 7, 2010, at local afternoon. View a 800 pixel-wide version of the above mosaic HERE [NASA/GSFC/Arizona State University].

Because both Archimedes and Imbrium basin are flooded by mare basalt, their formations must be older than the volcanic activity. Furthermore, because Archimedes is located within Imbrium basin, Archimedes must be younger than Imbrium. Just by studying relationships between features, scientists can piece together their history!

Explore more of Archimedes' floor in the NAC frame!

Archimedes from the northwest, high over Mare Imbrium and in HDTV from Japan's SELENE-1 (Kaguya). Further south are, appropriately enough, the Montes Archimedes and further left, at the foot of the Appenines marching beyond the horizon, is Palus Putredinus site of Hadley Rille and the 1971 Apollo 15 expedition. View a larger image HERE [JAXA/NHK/SELENE].

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