Understanding the Limits of Simple Thermal Models for Characterizing Near-Earth Asteroids

Abstract

Understanding the properties of near-Earth asteroids (NEAs) is key for many aspects of planetary science, such as questions regarding solar system formation and planetary defense. Our current knowledge of NEA sizes and regolith properties is heavily dependent on simple thermal models. However, these models have inherent limitations due to the simplifying assumptions that they make about asteroid shapes and other properties. As a result, there is the potential for inconsistencies in model results. These inconsistencies are particularly prevalent when comparing model results based on ground-based data to model results based on space-based surveys such as WISE and NEOWISE. In this dissertation, I probe the nature of these uncertainties and seek to better understand the situations in which they arise. I start by doing a case study of the NEA 1998 QE2, observing it with both IRTF SpeX and NEOWISE. I describe a technique for using these data to place tighter constraints on the results of simple thermal models, and identify potential issues with the NEOWISE data (Chapter 2). I then do an in-depth investigation into using NEOWISE data for NEA characterization. I compile a complete recipe for NEA data analysis and develop a novel method for incorporating NEOWISE color corrections (Chapter 3). I then incorporate this analysis into an expansion of the initial case study, looking at eight different NEAs. I find particular issues with the NEOWISE data when looking at binary objects. (Chapter 4). Finally, I take a moment to discuss the policy implications of scientific research like that described here (Chapter 5). Overall, this work highlights the importance of better understanding the limitations of simple models as applied to large survey data sets like NEOWISE, and how the impacts of that understanding can be incorporated into broader space policy.