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

TL;DR

This study creates detailed compositional and temperature maps of Pluto's surface using New Horizons LEISA data, overcoming previous limitations through advanced data processing and joint retrieval methods.

Contribution

It extends prior compositional studies by combining multiple observations into high-resolution maps and jointly retrieving surface temperature, ice compositions, and grain sizes.

Findings

Maps show distribution of methane, nitrogen, water ices, and Titan tholins.

Temperature map correlates with surface composition.

Enhanced data processing techniques improve map accuracy.

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.