Featured Image - February 3, 2009
Sklodowska Crater

Sklodowska crater (127 km diameter; named after Marie Sklodowska-Curie, the famous chemist) is located on the eastern limb of the Moon (18.2 ° N, 95.5 ° E), southeast of Mare Smythii. Smaller (i.e., less than about 20 km diameter) craters on the Moon, like Sulpicius Gallus, are bowl-shaped. However, craters that are larger than 20 km transition into what are called complex craters like the Imbrium-aged Sklodowska (Figure 1) and have terraced walls with a central peak. We have no samples from this crater, but geologic mapping using remotely-sensed data indicates that it formed at roughly the same time (geologically speaking) as nearby Tsiolkovsky Crater.

 
Figure 1.Sklodowska crater, a complex lunar crater located on the Moon's eastern limb. (Apollo Image AS15-M-1968 [NASA/JSC/Arizona State University])

In Figure 1 you can clearly see Sklodowska's well-defined central peak and terraced walls. The central peak formed when the materials in the center of the impact zone beneath the crater, which had been heavily compressed by the shock of the initial impact, rebounded. The terracing on Sklodowska's crater walls is thought to have occurred as one of the last steps of the crater-forming process. The crater wall materials, which were weakened and fractured by the impact, succumbed to the pull of the Moon's gravity and slumped following the original impact event. From the initial impact to the final slumping, this complicated process took only minutes to complete.

The Moon's intensely cratered surface bears witness to the power and frequency of impacts throughout the history of the Solar System. The impact process is affected by many factors, including the size and speed of the bolide, and the composition of the target materials. Impact craters provide lunar scientists the opportunity to determine relative ages of materials, compositional variations at depth, and the thickness of the lunar regolith. One of the key objectives of the forthcoming Lunar Reconnaissance Orbiter Camera will be to study lunar impact craters at incredibly high resolutions (50cm/pixel) which will help us to better understand the physics of the crater-forming process.

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