An in-depth look at the lunar crater Copernicus: Exposed mineralogy by high-resolution near-infrared spectroscopy

Abstract

Newly acquired, sequentially spaced, high resolution near-infrared spectra across the central section of crater Copernicus' interior have been analysed using a range of complementary techniques and indexes. We have developed a new interpretative method based on a multiple stage normalisation process that appears to both confirm and expand on previous mineralogical estimations and mapping. In broad terms, the interpreted distribution of the principle mafic species suggests an overall composition of surface materials dominated by calcium-poor pyroxenes and minor olivine but with notable exceptions: the southern rim displays strong ca-rich pyroxene absorption features and five other locations, the uppermost northern crater wall, opposite rim sections facing the crater floor, and the central peak Pk1 and at the foot of Pk3, show instead strong olivine signatures. We also propose impact glass an alternative interpretation to the source of the weak but widespread olivine-like spectral signature found in low-reflectance samples, since it probably represents a major regolith constituent and component in large craters such as Copernicus. The high quality and performance of the SIR-2 data allows for the detection of diagnostic key mineral species even when investigating spectral samples with very subdued absorption features, confirming the intrinsic high-quality value of the returned data.

Photogeologic analysis of impact melt‐rich lithologies in Kepler crater that could be sampled by future missions

“…Similarities between Kepler and Aristarchus include, for example, a distinct topographic bench between the crater wall and the subsided melt‐rich floor material (Figure 7; [ Strom and Fielder , 1970; Guest , 1973]), radial groove‐like melt‐erosion channels on the crater wall (Figure 8; [ Mustard et al , 2011]), and exterior impact melt flows with thicknesses on the order of 1–10 m (Figure 10; [ Zanetti et al , 2011b]). Collapse pits in melt‐rich deposits (Figures 5 and 15) have been described from Copernicus [ Bugiolacchi et al , 2011] and King [ Ashley et al , 2011], and found in numerous other craters as well [ Wagner et al , 2011]. As discussed above, rheologic properties of the Kepler impact melts, as inferred from flow morphometry and calculations, are comparable to those estimated and observed in other lunar craters.…”

“…Ponding of exterior melt‐rich deposits (Figure 10) and concentration of the ponds in the inferred downrange direction (Figure 4) has been observed in a number of complex craters, like Tycho [e.g., Shoemaker et al , 1968; Howard and Wilshire , 1975; Hawke and Head , 1977; Schultz and Anderson , 1996; Morris et al , 2000; Hirata et al , 2009], King [e.g., Howard , 1971, 1972; El‐Baz , 1972; Howard and Wilshire , 1975; Heather and Dunkin , 2003], and Jackson [ Hirata et al , 2010]. Copernicus [e.g., Schmitt et al , 1967; Howard , 1975; Bugiolacchi et al , 2011] and Tycho are well‐known examples of asymmetric distribution of melt‐rich floor materials, with Tycho showing a downrange concentration of smooth floor material [ Schultz and Anderson , 1996] similar to Kepler (Figure 4). Similarities between Kepler and Aristarchus include, for example, a distinct topographic bench between the crater wall and the subsided melt‐rich floor material (Figure 7; [ Strom and Fielder , 1970; Guest , 1973]), radial groove‐like melt‐erosion channels on the crater wall (Figure 8; [ Mustard et al , 2011]), and exterior impact melt flows with thicknesses on the order of 1–10 m (Figure 10; [ Zanetti et al , 2011b]).…”

Study of the Buried Basin C-H, Based on the Multi-Source Remote Sensing Data

“…This is a highly diverse morphological area and is characterized by peaks and elevated terrains (Nbm in Figure 1c). In addition, it is punctuated by valleys and low-elevation corridors that are mostly flooded with mare-like materials (Em and Im2 in Figure 1c) [22]. The occurrence of the Copernicus impact resulted in the formation of an ejecta blanket (The largest Cc part in Figure 1c).…”

Large mineralogically distinct impact melt feature at Copernicus crater – Evidence for retention of compositional heterogeneity

“…[3] Copernicus is a 96 km diameter, young complex impact crater [~779 m.y. ; e.g., Hiesinger et al, 2012] located on the lunar near-side, extensively studied using telescopic [e.g., Pieters, 1982;Lucey et al, 1991;Pinet et al, 1993] and spacecraft observations [e.g., Pieters et al, 1994;Le Mouélic and Langevin, 2001;Ohtake et al, 2009;Bugiolacchi et al, 2011]. The pre-impact stratigraphy (top to bottom) has been suggested to be [Schmitt et al, 1967]: (1) mare basalts, (2) Imbrium ejecta (Fra Mauro Formation), and (3) upper crustal material (pre-Imbrian megaregolith and anorthosites) [e.g., Hiesinger and Head, 2006, Figure 1.20].…”