New surface composition and temperature maps of Pluto from New Horizons LEISA data

Abstract

New Horizons RALPH/LEISA near-infrared spectra allow for regional mapping of Pluto's surface ices and their physical state; however, scan-to-scan artifacts and variable spatial resolution complicate quantitative interpretation. We extend previous LEISA compositional studies (Protopapa et al., 2017(arXiv:2110.00662); Schmitt et al., 2016; Emran et al., 2023(arXiv:2301.06027)) by combining five close-approach observations into co-registered equirectangular maps at 7 km/pixel and by jointly retrieving surface temperature, ice abundances, and grain sizes using a Hapke-based mixing model. We mitigate bad pixels and edge overexposure linked to flat-field uncertainties and correct for residual scan-to-scan spectral discrepancies using per-observation scale and offset terms. The resulting maps provide distributions of CH4-rich ice, N2-rich ice, H2O ice, and Titan tholins, alongside a corresponding temperature map.