IRTF Data Archive Program Information

# # Program information file # PROGRAM_ID 2023A014 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 Kiana McFadden 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 the multiple 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. All but two are scheduled for radar observations at Goldstone. Four targets are potentially hazardous [PHAs]. Asteroids Ivar and Mithra have existing radar data and well-constrained shape models. Asteroid 2002 KL6 has previous radar images and is irregular. Previous SpeX LXD observations exist for Ivar and 2002 KL6 in the IRTF archives, which will allow us to validate those 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. Observations of each object will be obtained at three different viewing geometries [i.e., on three different dates] at a minimum. The total time request of 57 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