# # Program information file # PROGRAM_ID 2024A019 PROGRAM_TITLE Investigating the regolith properties of NEAs: Thermophysical modeling constrained by IRTF/SpeX observations and shape information. PROGRAM_INV1 Ellen Howell PROGRAM_INV2 Ronald Vervack PROGRAM_INV3 Yanga Fernandez PROGRAM_INV4 Mary Hinkle PROGRAM_INV5 Samuel Myers PROGRAM_SCICAT near-Earth objects PROGRAM_ABSTRACT_BEG We propose to measure both reflected and thermal spectra of near-Earth asteroids [NEAs] between 0.7-5.1 microns with SpeX. Our science goal is to investigate the regolith properties of small NEAs by using detailed thermophysical models incorporating the shape and spin state. We explore how the complex shapes, spin states, and regolith properties of NEAs affect the thermal flux and their derived sizes and albedos by comparing our results to other thermal models, such as NEATM. By observing these targets at multiple viewing geometries, we are also investigating the level of heterogeneity in the surface properties that is often required to explain all of the thermal observations. By comparing the thermal model results using detailed shape models versus lightcurve shape models we will examine the importance of concavities and surface features to the derived thermal parameters. We propose to observe 7 NEAs this semester. Asteroids 1685 Toro, 2011 UL21 and 2013 NK4 are scheduled for radar observations at Goldstone. Two targets are potentially hazardous [PHAs]. Asteroids Toro and 1566 Icarus have existing radar data and well-constrained shape models. Asteroid 2063 Bacchus has previous radar data and appears to be a contact binary. Previous SpeX LXD observations exist for Toro and Icarus in the IRTF archives, allowing us to validate thermal models across apparitions. For each NEA we will use prism mode [0.7-2.5 microns] for mineralogy and to measure the reflected component of the spectrum, and we will use LXD-long to measure the thermal flux between 2.0-5.1 microns. We will observe each object at three different viewing geometries [i.e., on three different dates]. The total time request of 58 hours includes time for telescope slews, flats and arcs, and standard stars, and is optimized for the overlap between targets where possible for observing efficiency. PROGRAM_ABSTRACT_END