Near-Earth asteroids are not uniform: Using thermal models of multiple observations to reveal inhomogeneities

University Of Arizona, Tucson AZ

Investigators

Abstract

Asteroids can be studied both by the light they reflect and by the infrared thermal radiation (heat) they emit. The investigators have developed a sophisticated technique for studying asteroids that make close approaches to the Earth (known as Near-Earth Asteroids, or NEAs). They will use their thermophysical model (TPM), together with visible and radar observations of NEAs to investigate the surface properties of the asteroids. While some asteroids are known to have smooth surfaces, others are covered with a thick layer of dust, and still others have regions of each type of surface. These different regions emit and reflect radiation differently, and thus it is important to know the nature of an NEA's surface when interpreting observations. The investigators will use their thermophysical model to interpret reflected and emitted light from NEAs and will identify possible targets for future missions. It should be noted that an understanding of the nature of NEAs would be vital to the defense of the nation should one be discovered on a collision course with Earth. The investigators will involve a postdoctoral student and a graduate student in outreach activities, which will include four workshops for K-12 teachers. Thermal modeling of asteroids reveals much about their surface properties. Simple thermal models often do not fit multiple observations of the same asteroid self-consistently. Both non-sphericity and surface heterogeneity are required to fully understand an asteroid. The investigators will use multi-epoch observations, with detailed shapes from optical lightcurves and radar data to leverage multiple observation geometries to model the thermal emission more realistically and better constrain the surface properties of NEAs. They will investigate such properties as the heterogeneity of the asteroid surfaces; the degree of roughness on each surface, the importance of thermal inertia and how it varies with size, spectral type, or rotation rate; and how derived thermal parameters using radar-derived shapes compare to those using optical lightcurve-derived shapes. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.