As we sample ever-smaller sizes of near-Earth asteroids (NEAs), we see an increasing variation in the range of physical properties. Radar experiments show a diverse range of shapes, surface features, and rotation states among NEAs. Infrared observations of these objects are equally varied, illustrating a range of spectral types and thermal characteristics. While spacecraft missions will reveal details of a few NEAs, only ground-based observations will provide an overall understanding of the population of these small bodies, for which the size and albedo distributions are still poorly understood. The goal of our investigation is to use both radar images and near-IR spectra to better understand the regolith of different types and shapes of NEAs. The regolith on an asteroid surface controls its thermal properties and often its radar reflectance as well, and at smaller sizes the irregular shape plays an increasingly important role. To accomplish our goal, we have established a program in which we choose NEAs that will be observed well enough with radar to have high-quality shape models and also observe these objects with SpeX at the NASA IRTF (2-4 microns) at several different viewing geometries and rotation phases to see how the inferred thermal properties depend on the detailed shape. We then use this knowledge to quantify the systematic biases in existing thermal models that are based on simple assumptions such as spherical shape or zero thermal inertia. We will present a summary of our observations to date and preliminary results of the thermal modeling.
|Journal||Bulletin of the American Astronomical Society|
|Publication status||Published - 1-Oct-2010|
|Event||42nd DPS meeting of the American Astronomical Society, 2010 - Pasadena, California, United States|
Duration: 4-Oct-2010 → 7-Oct-2010