Retrieving Surface Mineralogy with Future SBG Thermal Infrared Data

One of the Designated Observables (DOs) identified in the Decadal Survey for Earth SFcience and Applications from Space was Surface Biology and Geology (SBG). NASA has formulated this and several of the other DOs into the Earth System Observatory, which provides a framework from which to answer many of the questions posed by the Decadal Survey and address the goals of the DOs. The SBG mission concept, now in formulation, has an overarching goal of acquiring global hyperspectral visible to shortwave infrared (VSWIR; 0.38–2.5 μm) and multispectral mid and thermal infrared (MIR: 3–5 μm; TIR: 8–12 μm) image data at high spatial resolution (~30 m in the VSWIR and ~ 60 m in the TIR). The VSWIR and TIR are separate instruments on separate platforms and thus will have different characteristics such as local overpass and temporal revisit times as a function of the individual scientific objectives. The SBG-TIR is a joint-endeavor between NASA and ASI in Italy, with the instrument being built at the NASA Jet Propulsion Laboratory (JPL). It will have a wide swath width (935 km) resulting in a three-day equatorial revisit time. During Phase A development, the TIR spectral resolution was increased from five to six bands (plus the original two planned for the MIR). The addition of a 10.3 μm band vastly improves the capability of surface mineralogy mapping and aerosol detection in sulfur dioxide (SO
2
) plumes. For the first time, an Earth-orbiting TIR mission is planning an operational surface mineralogy (SM) L3 product. This product uses the L2 TIR surface emissivity data as input together with a spectral library of the most common Earth surface minerals to produce mineral and weight percent silica (WPS) maps of the Earth’s arid lands. Here, we describe the current SM algorithm testing and development, initial results, and plans for ongoing work prior to the planned 2028 launch.