UCLA

We have created a comprehensive set of laboratory bidirectional measurements of lunar soil samples from Apollo missions 11, 12, 15, 16 and 17. The lunar soil samples successfully fit photometric models from the laboratory data to the solar spectrum averaged hemispheric reflectance as a function of the incidence angle. The Apollo 11 (vial 10084) and Apollo 16 (vials 61141 and 68810) soil samples are representative end member samples from the Moon’s dark lunar maria and bright lunar highlands. We used our solar spectrum averaged albedos in a thermal model and compared our model-calculated normal bolometric infrared emission curves with those measured by the LRO Diviner Lunar Radiometer Experiment. We found excellent agreement at all of the Mare Apollo sites (Apollo 11, 12, 15 and 17) with Diviner at their landing sites. However, the sample from the Apollo 16 site, had an albedo measured in the laboratory that was 33% brighter than those required to fit the Diviner infrared data. We attribute this difference to increased compaction and decreased maturity of the laboratory sample relative to the natural lunar surface and to local variability in surface albedos at the Apollo 16 field area that are below the spatial resolution of Diviner. We address the idea of compaction as a possibility for the discrepancy of the Apollo 16 soil with additional measurements. We show that increasing the density and decreasing the porosity of the Apollo 11 and 16 samples increases the albedo of the samples. The albedo of the Apollo 16 highlands soil sample is nearly twice as sensitive to the effects of compaction as the mare Apollo 11 soil sample.