Ice deposits in the south polar region of Mars are in constant exchange with the atmosphere, allowing them to reflect near-term seasonal changes and preserve records of long-term climate variation (Buhler et al., 2020;Leighton & Murray, 1966;Smith et al., 2020). Like its northern counterpart, the south pole is blanketed each winter by CO 2 ice condensed from the atmosphere and hosts an extensive dome of interbedded water ice and dust (Plaut et al., 2007;Prettyman et al., 2009). These south polar layered deposits (SPLD) rise 3-4 km from the surrounding terrain and reflect 30-100 Myr of Mars climate history (Byrne, 2009). However, the south is unique in its retention of a 1-10 m-thick slab of perennial CO 2 ice, which is perched atop the south polar dome; together with surrounding water ice exposures, these CO 2 ice deposits comprise the south polar residual cap (SPRC).Over 50 years of close observation have revealed the SPRC and other south polar ices to be as complex as they are dynamic. Erosional pits and troughs (Byrne & Ingersoll, 2003;Thomas et al., 2005) are seen to grow

Multispectral mapping data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) provide a unique opportunity to characterize south polar ice deposits at higher spectral sampling, spatial resolution, or spatiotemporal coverage than previous work. This new perspective can help to constrain the nature and distribution of different mixtures of CO2 ice, H2O ice, and dust that influence the formation, evolution, and preservation of Mars climate records. We processed 1103 CRISM observations spanning southern summer of six Mars Years (MY) through a combination of k-means clustering and random forest classification. Using a set of 12 spectral endmembers directly tied to previous work with high-resolution CRISM targeted data, we made a series of temporally restricted mosaics showing surface spectral variation over time. The mosaics show the effects of the MY 28 dust storm on the removal of the seasonal CO2 ice cap that year and new details of how this process differed from the years that followed. A mosaic showing residual ice surfaces displays broad agreement with previous compositional maps while resolving new details in the distribution of H2O ice-rich material around the periphery of the bright CO2 ice cap. By showing how surface composition varies across a broad swath of the south polar region though time, the endmember set and classified mosaics produced in this work can provide critical context for future studies of the dynamic processes that shape south polar ice deposits.

This list includes many of the hundreds of current students and scientists who have made significant contributions to Mars Polar Science in the past decade. Every name listed represents a person who asked to join the white paper or agreed to be listed and provided some comments.