IMPROVED ROCK ABUNDANCE AND LUNAR NIGHTTIME TEMPERATURE MAPS FROM DIVINER

The Diviner Lunar Radiometer Experiment on the Lunar Reconnaissance Orbiter has been mapping the reflected solar and emitted infrared radiation of the Moon since July 5, 2009 [1]. Diviner has since collected over 500 billion radiometric measurements with excellent spatial and local time coverage. Temperatures derived from these measurements are diagnostic of the physical properties of the surface. For example, Bandfield et al. (2011) [2] presented a method for estimating the areal rock fraction within each Diviner pixel, leveraging the differences in thermophysical properties between rock and regolith. The most recently published global maps of nighttime temperature and derived thermophysical properties [2,3,4] use data collected from the start of the mission until 2016. Since that time, Diviner coverage has improved substantially. In this work, we compile the full ~12 years of Diviner data to produce improved nighttime brightness temperature, bolometric temperature, and derived regolith temperature and rock abundance maps of the Moon. The greater data volume results in improved spatial and local time coverage and better signal-to-noise ratios. In addition, we employ several key improvements to our data processing method: 1) Angular offset errors in instrument pointing have been corrected, resulting in improved localization of Diviner measurements; 2) past effective field of view (EFOV) modeling [5] used to determine the center of each Diviner observation accounting for topography and spacecraft motion has been optimized to produce sharper maps; 3) Curve fitting of nighttime temperatures is used to interpolate temperatures at a uniform local time; and 4) Slope modeling with up-to-date topographic maps has improved the removal of the effects of topography on nighttime temperatures. The resulting maps are noticeably sharper and have fewer data artifacts than previously available maps. We estimate a ~2-3x increase in the effective resolution of Diviner maps. These products allow for the exploration of lunar geology at a much finer scale than was previously possible.

[1] Paige et al. (2010) Space Sci. Rev. 150, 125-160. [2] Bandfield et al. (2011) JGR: Planets, 116. [3] Williams et al. (2017) Icarus 283, 300-325. [4] Hayne et al. (2017) JGR: Planets 122, 2371-2400. [5] Williams et al. (2016) Icarus, 273, 205-213.