Constraining the Limitations of NEATM-like Models: A Case Study with Near-Earth Asteroid (285263) 1998 QE2

TL;DR

This study evaluates the limitations of simple thermal models for NEAs by comparing them with complex models and data, using asteroid 1998 QE2 as a case study, and proposes methods to improve property constraints.

Contribution

The paper systematically assesses the limitations of NEATM-like models and introduces a method to better constrain NEA properties using simple thermal models.

Findings

Simple thermal models can effectively constrain NEA properties like albedo and thermal inertia.

Model uncertainties are affected by topography, viewing geometry, and data wavelength range.

The case study of 1998 QE2 demonstrates the practical application and limitations of these models.

Abstract

Near-Earth Asteroids (NEAs) are a key testbed for investigations into planet formation, asteroid dynamics, and planetary defense initiatives. These studies rely on understanding NEA sizes, albedo distributions, and regolith properties. Simple thermal models are a commonly used method for determining these properties, however they have inherent limitations due to the simplifying assumptions they make about asteroid shapes and properties. With the recent collapse of the Arecibo Telescope and a decrease of direct size measurements, as well as future facilities such as LSST and NEO Surveyor coming online soon, these models will play an increasingly important role in our knowledge of the NEA population. Therefore, it is key to understand the limits of these models. In this work we constrain the limitations of simple thermal models by comparing model results to more complex thermophysical models, radar data, and other existing analyses. Furthermore, we present a method for placing tighter constraints on inferred NEA properties using simple thermal models. These comparisons and constraints are explored using the NEA (285263) 1998 QE2 as a case study. We analyze QE2 with a simple thermal model and data from both the NASA IRTF SpeX instrument and NEOWISE mission. We determine an albedo between 0.05 and 0.10 and thermal inertia between 0 and 425 J m$^{-2}$ s$^{-1/2}$ K$^{-1}$. We find that overall the simple thermal model is able to well constrain the properties of QE2, however we find that model uncertainties can be influenced by topography, viewing geometry, and the wavelength range of data used.