Imaging of lunar surface maturity

Abstract

Abstract. The physical evolution of the lunar surface with exposure to the space environment is termed maturation, and maturity is the degree to which a particular lunar soil possesses quantitative characteristics consistent with that exposure. Several quantitative measures or indices of maturity have been proposed and employed, including the abundance of solar wind gas, abundance of various types of agglutinates, va:'ious measures of grain size, and ls/FeO. Among the changes attendant with space exposure are striking changes in the optical characteristics of soils. Mature lunar soils are dark red and exhibit reduced spectral contrast relative to immature soils. This paper presents an optical maturity index that quantifies the spectral effects of maturation. We show that this optical maturity index correlates with other maturity indices about as well as the accepted maturity indices correlate among themselves and is only weakly coupled to composition. The modest correlations among maturity indices suggest important controls on individual maturity indices other than age, uncorrelated variations in the rates of accumulation of individual indicators, or variations in depths over which indicators are eraplaced. In addition to mixing, these efibcts conspire to reduce the equivalence of maturity and duration of surface exposure. Optical maturity illustrates some of these effects, showing that ejecta of large and small craters •nature at different rates and that the interiors and ejecta of large craters exhibit systematically different optical maturities. The same or analogous effects are likely to influence other maturity indices.

Global Regolith Thermophysical Properties of the Moon From the Diviner Lunar Radiometer Experiment

“…In contrast, low-thermal inertia anomalies are predominantly contained in the thousands of cold spots-vast disrupted regions surrounding~1 km and smaller fresh impact craters~100 kyr in age . Notably, all of these impact-related features are <1 Gyr old, explaining the general correlation of optical maturity (Lucey et al, 2000) and thermal inertia; features older than about a billion years have been erased by erosion.…”

“…Lucey et al (2000) derived a quantitative optical maturity index (OMAT) based on observed spectral changes with age, which can be used to infer relative exposure ages of lunar surface materials. Although OMAT is known to be influenced by mineral composition and geologic setting, thermal inertia is not directly affected by composition (Fountain & West, 1970;Wechsler et al, 1972).…”

Volcanic history of the Imbrium basin: A close-up view from the lunar rover Yutu

“…S2), which is suggestive of a young age for the Chang'e-3 landing site. However, it has been noticed that there was no clear correlation between the optical maturity index and the ages of the Apollo mare soils (18).…”

“…The estimated FeO contents are consistent with the APXS analyses within analytical uncertainties. The space weathering effect (darkening and reddening of the spectra) of the lunar soil can be indicated by the optical maturity index (18), which ranges from 0.098 to 0.158 with an exception of 0.312 for CD005 (SI Appendix, Table S2). The higher values of the optical maturity index and the spectral reflectance of CD005 may be due to blowing the top dusts off the lunar surface by the rocket during the descent of Chang'e-3 because CD005 is located closest to the lander (SI Appendix, Table S2).…”

Geometric Calibration of the Clementine Uvvis Camera Using Images Acquired by the Lunar Reconnaissance Orbiter

“…Using images collected while in lunar orbit from the Ultraviolet/Visible (UVVIS) camera (Kordas et al, 1995;McEwen and Robinson, 1997), scientist generated a detailed global multispectral mosaic and a series of mineralogy and maturity maps (Edwards et al, 1996;Robinson et al, 1999;Lucey et al, 2000a;Lucey et al, 2000b). To facilitate the mapping exercises, efforts were made to geodetically control the images into a global control network.…”