Asteroid thermophysical modeling

The field of asteroid thermophysical modeling has experienced an extraordinary growth in the last 10 years, as new thermal-infrared data became available for hundreds of thousands of asteroids. The infrared emission of asteroids depends on the body’s size, shape, albedo, thermal inertia, roughness, and rotational properties. These parameters can therefore be derived by thermophysical modeling of infrared data. Thermophysical modeling led to asteroid size estimates that were confirmed at the few-percent level by later spacecraft visits. We discuss how instrumentation advances now allow mid-infrared interferometric observations as well as high-accuracy spectrophotometry, posing their own set of thermal-modeling challenges. We present major breakthroughs achieved in studies of the thermal inertia, a sensitive indicator for the nature of asteroids soils, allowing us to, e.g., determine the grain size of asteroidal regoliths. Thermal inertia also governs nongravitational effects on asteroid orbits, requiring thermophysical modeling for precise asteroid dynamical studies. The radiative heating of asteroids, meteoroids, and comets from the Sun also governs the thermal stress in surface material; only recently has it been recognized as a significant weathering process. Asteroid space missions with thermal-infrared instruments are currently undergoing study at all major space agencies. This will require a high level of sophistication of thermophysical models in order to analyze high-quality spacecraft data.