Moon Science: Impact Crater & Ejecta | NASA's Lunar Reconnaissance Orbiter

Moon Science: Impact Crater & Ejecta | NASA's Lunar Reconnaissance Orbiter

Fresh concentric impact crater (245 m diameter) found in northwest Mare Nubium. Note concentric ring inside the crater wall, the circular flat floor and the dark central pit. Blocks are strewn along the bright crater rays extending away from the rim. 

NAC M1287235559L

The 245 m concentric crater under late afternoon illumination  highlighting the topography. NAC M181230113L

Boulders up to about 10 m in diameter where ejected from the crater. Upon impact, the boulders skidded across the surface leaving a trough behind them.

Mare Nubium (Latin "sea of clouds") is a lunar mare in the Nubium basin on the Moon's near side. The mare is located just to the southeast of Oceanus Procellarum. The unique morphology of craters, such as this one (-17.25°S, 350.46°E), is the result of a contrast in the strength of a surface layer (in this case, the unconsolidated regolith) and a stronger underlying layer (here, mare basalt). The relatively weak regolith is more easily excavated than the basalt, resulting in the distinct "inner ring". For a given thickness of regolith (typically meters thick), craters formed entirely within the regolith are bowl-shaped. At increasing diameters, the crater excavates below the regolith into the stronger basalt flows, and they exhibit a central mound, a flat floor, and finally a concentric ring inside the crater rim.

Immediately inside the rim is a ridge with a diameter of about 167 m; the ridge itself is about 50-70 m wide and stands about 20 m above the adjacent crater floor. The center of the crater is marked by a low-reflectance rough area about 36 m in diameter, surrounded by a subtle ridge.

Scattered across the inner ridge and crater rim and extending beyond the crater rim is bright, bouldery ejecta. Boulders as large as 11 m have been ejected from the crater. The bright ejecta forms a more or less continuous blanket around the rim extending to 90-150 m. At greater distances, the ejecta breaks up into a series of rays of finer material that extend as much as 1 km from the rim.

Several of the larger boulders lie at the end of shallow troughs, indicating that they slid across the surface upon landing.

Image Credit: NASA/GSFC/Arizona State University
Release Date: June 6, 2025

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