Dr. Joshua Emery

December 20, 2006

"Surface Compositions of KBOs, Centaurs, and Low Albedo Asteroids: Constraints from IRAC Reflectance Measurements"

JPL 1276917

We indend to measure broadband fluxes of a sample of Kuiper Belt Objects (KBOs), Centaurs, and low albedo asteroids with IRAC. Ground-based spectra have been recorded from the visible to 2.5 microns for all objects in the target list, but spectral models admit a range of possible compositions. Reflectance in two or, in some cases, three bands (3.6, 4.5, and 5.8 microns) will allow discrimination between possible spectral models, thereby constraining surface compositions. For several objects, thermal emission will be detected in the 8.0-micron band. The simultaneous measurement with IRAC of both reflected and emitted flux will permit estimation of size and albedo for these objects. Compositions of these primitive bodies allow analysis of conditions in the outer solar nebula during formation, diversity in the Kuiper Belt, and possible dynamical and evolutionary links between KBOs, Centaurs, and low albedo asteroids.