The Compaction of Moondust

Abstract

The Moon is covered by a blanket of rock fragments and loosely bound dust particles called regolith. This layer is key in deciphering the evolution of the Moon and the terrestrial planets, including Earth. It is also a protagonist in the return of humanity to the Moon after its last visit over half a century ago. The main concern for lunar regolith studies is the determination of compactness. Compactness may be expressed as porosity and can be determined by the discrepancy between bulk density estimates from the gravity field and grain density estimates from material composition. New state-of-the-art gravity models of the Moon allow for small-scale gravity studies of regolith porosity, which have resulted in better understanding of the Moon's thermal evolution. However, regional variations in compactness are currently poorly known due to the ambiguous nature of gravity data. Ideally, an additional information source is desired to provide constraints on regolith compaction. It might be that the amount of reflected sunlight from the lunar surface provides additional constraints on regolith compactness. For example, incident light can enter a more porous material deeper, increasing the probability of absorption and decreasing the amount of reflected light. Therefore, this thesis will explore the scattering behaviour of reflected sunlight from the lunar surface as a potential additional information source.