Solar system observations with Spitzer Space Telescope: Preliminary results

The programs of observations of Solar System bodies conducted in the first year of the operation of the Spitzer Space Telescope as part of the Guaranteed Observing Time allocations are described. Initial results include the determination of the geometric albedos of a number of Kuiper Belt objects and Centaurs from observations of their flux densities at 24 and 70 μm, and the detection of emission bands in the spectra of several distant asteroids (Trojans) around 10 and 25 μm. The 10 Kuiper Belt objects observed to date have geometric albedos in the range 0.08-0.15, significantly higher than the earlier estimated 0.04. An additional KBO [(55565) 2002 AW197] has a geometric albedo of 0.17 ± 0.03. The emission bands in the asteroid spectra are indicative of silicates, but specific minerals have not yet been identified. The Centaur/comet 29P/Schwassmann-Wachmann 1 has a nucleus surface geometric albedo of 0.025 ± 0.01 and its dust production rate was calculated from the properties of the coma. Several other investigations are in progress as the incoming data are processed and analyzed.