The osiris-REX thermal emission spectrometer (otes) measured the infrared radiance emitted from asteroid (101955) bennu globally at different local times. These observations are a composite of two…

This federal contract award, with ID 80NSSC23K0664, was granted by the Shared Services Center (a civilian agency) to Northern Arizona University (NAU) for a research project related to the OSIRIS-REx mission's Thermal Emission Spectrometer (OTES) data. The goal is to improve the analysis of the asteroid Bennu's surface composition and spatial variability by accounting for the anisothermality, or uneven temperature distribution, on Bennu's rough surface. The $292,557.00 grant does not have a set-aside designation, indicating NAU's competitive capabilities in securing federal research funding. This work is relevant to NASA's New Frontiers program and will complement future analyses of the samples being returned from Bennu's surface.

The osiris-REX thermal emission spectrometer (otes) measured the infrared radiance emitted from asteroid (101955) bennu globally at different local times. These observations are a composite of two important pieces of information for understanding bennu s regolith, the planck-like radiance revealing surface temperature and the emissivity spectrum providing constraints on mineralogy. When separating these two components to derive apparent temperature and mineralogy, a classical approach is to use a single temperature planck blackbody (e.g., isothermal). This assumption has been shown to be inadequate for many airless bodies where a conductive atmosphere is absent and CM- to m-scale shadowing can introduce dramatic thermal gradients within a scene. This is especially true for bennu where the rotation period is rapid (~4.3 HR.) and the surface is rough at scales equivalent to and much smaller than the otes field-of-view, greatly inhibiting equilibration of the surface temperature. This anisothermality must be accounted for to properly interpret the surface temperature and mineralogy. To date, otes emissivity investigations have not adequately compensated for this anisothermality rendering portions of the spectrum unusable and introducing subtle distortions of diagnostic absorption features. Here we propose to rectify these issues and provide more accurate emissivity data that will be used to improve the analysis of bennu s composition and spatial variability. The proposed work is relevant to NASA and the new frontiers program because IT seeks to improve and analyze a globally and temporally expansive existing dataset to provide new insights to the surface composition of bennu. Furthermore, this analysis will complement future analyses of the samples being returned from bennu s surface.