Lunar Reconnaissance Orbiter Camera

Mare Frigoris Constellation Region of Interest

The floor of a l.2-km diameter crater in the Mare Frigoris Constellation region of interest. Samples of this material could help us understand the complex geologic history of this region of the Moon. NAC image M126752534RE; scene width is 510 m [NASA/GSFC/Arizona State University].

Samples from small, relatively fresh craters like the one above may someday help us learn more about Mare Frigoris and its place in lunar geologic history. Mare Frigoris is located on the lunar nearside, to the north of the Imbrium and Serenitatis basins. Instead of being low in reflectance like typical mare basalts, its reflectance is intermediate between the mare to the south and highlands terrain to the north. This is likely due to a lower iron and titanium content than any of the sampled mare basalts, making it an intriguing end-member in the spectrum of lunar mare volcanism.

Clementine mosaic [USGS] of the lunar nearside showing the approximate location (black arrow) of the Mare Frigoris Constellation region of interest.

Portions of Mare Frigoris, like the area near the Constellation region of interest outlined below, are so high in reflectance they're considered "light plains." Light plains can form in several different ways: through volcanism, with a composition even lower in iron and titanium; as the result of impact basin ejecta, which acts as a fluid, filling in topographic lows; or as ancient volcanic plains that were subsequently covered with a thin layer of highlands material ejected from nearby craters or basins which masks the true basaltic surface (a hidden, or "cryptomare"). Small craters like the one above excavate material from below the surface, and can help discern whether or not the material there is distinct in composition (as would be expected for cryptomare). Sampling this material would provide a definitive resolution to the geologic history of this fascinating region.

A WAC image showing the 40x40 km box centered on the Frigoris region of interest. Arrow indicates the location of the NAC image above. Image number M119673851ME [NASA/GSFC/Arizona State University].

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