# # Program information file # PROGRAM_ID 2024B071 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 5 NEAs this semester. Asteroids 1998 TU3, 1998 ST27 have previous radar observations, and along with 2010 EW45 are scheduled for radar observations at Goldstone. The NEAS 1998 ST27 and 2010 EW45 are potentially hazardous [PHAs]. Asteroid 1036 Ganymed has existing radar data and a lightcurve shape model. Asteroid 887 Alinda is well-placed for extended IRTF observations. Previous SpeX LXD observations exist for Ganymed 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 54 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