Chain of secondary craters in Mare Orientale
A small secondary crater chain near the southwestern margin of Mare Orientale, within the Inner Rook Mountains. The ~125-meter-long chain lies within one of the Constellation Program regions of interest in the Orientale multi-ring basin. Image is about 530 meters across, M112224591R [NASA/GSFC/Arizona State University].
This small chain of several craters likely formed from material ejected during the formation of a larger distant crater. The craters range from ~20 to ~30 meters in diameter and the entire chain is only ~125 m long. The irregular nature of the craters' floors and rims suggests that these are secondary craters rather than primary craters. Most chains of craters on the Moon are formed in this manner, but a few, like the 50-km-long Davy Catena (crater chain), are thought to have formed as a result of a series of impacts by fragments from a comet or asteroid that was disrupted when passing close to Earth.
The 50-km-long Catena Davy at 10.9°S, 353.5°E in LROC WAC frame M119896473ME; north is up. [NASA/GSFC/Arizona State University]
The small crater chain lies inside of the Inner Rook Montes toward the south-western edge of Mare Orientale. Orientale 1 is one of two sites near the Orientale Basin identified as regions of interest to the Constellation Program. It is of interest because of the proximity of highlands regolith and the Orientale Basin impact melt sheet, which is heavily fractured to the north of the site, as well as for its location on the limb of the Moon as seen from Earth, making radio communications easier. Obtaining a sample of the impact melt would allow scientists to date the formation of the Orientale basin, one of the youngest large basins on the Moon.
The small white rectangle near the top of this image illustrates the location of the NAC image with the small crater chain and the scale of the Orientale multi-ring basin. The Inner Rook Montes run across the middle of the frame and the Outer Rook Montes lie to the bottom. These mountains are parts of two rings that surround Mare Orientale. LROC WAC image M102788066ME; north is up. [NASA/GSFC/Arizona State University]
NAC image M112224591R was acquired on 7 November 2009 from an altitude of 53.5 km and has a pixel scale of ~0.55 m.
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