Asteroid thermophysical models: harnessing the NEOWISE dataset

Thermophysical models of asteroids combine shape and spin state information (derived from light curve or radar observations) with calculations of radiation and heat flow. This process constrains the thermal inertia of the surface of the asteroid, and may indicate surface composition and compaction state (e.g. loose rubble pile, coherent rock, metal). These results address a variety of goals. Constraining composition is valuable for asteroid characterization as well as estimating the impact hazard of potentially hazardous asteroids. As asteroids are targets of several current and planned robotic missions, constraints on regolith characteristics are valuable to spacecraft and sample collection designers. Furthermore, measurements of thermal conductivity and heat capacity (components of thermal inertia), can refine predictions of the Yarkovsky drift, a non-gravitational force that can altar asteroid orbits. We describe a project to thermophysically model asteroids observed by NEOWISE, the small-bodies hunting portion of the WISE infrared space telescope. NEOWISE observed over 150,000 minor planets over four infrared wavelength bands (Mainzer et al. 2011) during the first portion of its mission. We present results from thermophysical modeling of asteroids using NEOWISE infrared observations at 3.4, 4.6, 12 and 22 microns, and discuss the advantages and disadvantages of two modeling approaches for this work.