Joshua P. Emery
My main research focus is analysis of compositions of small bodies of the Solar System. Their small size grants these objects the virtue of having undergone far less endogenic alteration than the planets and large moons. Their surface compositions are therefore far more diagnostic of conditions (composition, temperature, pressure, etc.) in the solar nebula at the time when planets were forming than are rocks we pick up on Earth, or even the Moon or Mars. Of particular interest is investigating the distribution of organic material in the Solar System.
The geological information stored in these bodies must often be accessed with astronomical techniques. I use ground-based and space-based telescopes to investigate surface compositions. My primary effort recently has used the Spitzer Space Telescope to study thermally emission in the mid-infrared (5 to 40 microns). Spectroscopy in this wavelength region is particularly sensitive to silicate (rocky) mineralogy. This ongoing work has already revealed that several distant asteroids exhibit silicate mineralogy that is similar to that of comets, but distinct from most asteroids in the main asteroid belt. Since different structures respond differently to heat input (e.g., solid rock changes temperature more slowly than sand), these observations also provide constraints on the structure of the surface layer (i.e., dusty regolith like the moon, solid rock, or metallic surface).
Many distant asteroids (a > 3.5 AU), Centaurs, and KBOs have very low albedos (reflectivity) and "red" spectral slopes (increasing reflectance with increasing wavelength). These properties are generally hypothesized to be due to the presence of complex organic molecules on the surfaces. I use ground-based telescopes as well as Spitzer to search for diagnostic signatures of these molecules in order to test this hypothesis. These observations focus on the near-infrared (0.8 to 4.5 microns) wavelengths, where the measured flux is dominated by sunlight reflected off of the surfaces, and are also sensitive to silicate mineralogy as well as the presence of ices.
Department of Earth and Planetary Sciences
1412 Circle Drive
Knoxville, TN 37996-1410
Phone: (865) 974-8039