Space Weathering at the Moon

In this paper we summarize the substantial recent progress in understanding space weathering that has occurred through technical innovations in the laboratory and in space, including employment of ultra-high-resolution imaging of lunar samples, a wave of new remote sensing observations, samples returned from asteroid regolith, and new methods for simulating space weathering to gain insight into its mechanisms. The paper begins with a summary of space weathering processes and their observed effects on lunar samples (Section 2). It then describes new insights gleaned from remote sensing at a broadened range of wavelengths (Section 3.1) and from observations of special lunar environments where space weathering inputs vary, such as the intensity of solar wind at lunar swirls or in permanent shadow in polar regions (Section 3.2). We then outline how laboratory simulations have informed the understanding of space weathering mechanisms and rates (Section 4). Finally, we discuss the integrated observations and simulations and the current state of our knowledge (Section 5) and make suggestions for future investigations (Section 6).