PI: Jason C. Cook, Arizona State University, Jason.Cook3@asu.edu
Address: Dept. of Physics and Astronomy, Tempe, AZ 85287, USA
CoI: Susan Wyckoff, Arizona State University
Title: Spectroscopy of Pluto and Charon Between 1.4-2.5 (mu)m
Abstract: At the outer bounds of the solar system, Pluto and Charon may represent the largest of the Kuiper Belt Objects (KBOs). To better understand the physical properties of Pluto and Charon, and to provide insights into their origin and evolution in the context of other outer solar system objects, we propose a spectroscopic program to study the atmosphere of Pluto and the surface of Charon using Gemini North and South. Based on surface composition and sublimation thresholds, N_2, CH_4 and CO should comprise Pluto's atmosphere. However, only CH_4 has been detected to date (Young \emphet al., 1997). Non-constraining upper limits for CO (Young \emphet al., 2001) and for several hydrocarbons (Krasnopolsky, 2001) have been observed. Two occultations in 2002 showed Pluto's atmosphere had changed since perihelion in 1989 indicating greater surface pressure and temperature. Measurements of the atmospheric CH_4 and CO are needed to constrain models, and determine changes in the CH_4 abundance since 1992. The surface of Charon is mainly covered by crystalline H_2O ice. Additional ices expected in the 1.4-2.5 (micron) region include CO_2, NH_3 and CH_4 (Roush, 1994; Brown & Calvin, 2000), but have eluded detection to date due to low resolution and poor signal-to-noise (SNR). Rotationally resolved spectra of Charon will be obtained to search for the presence and distribution of these ices. For those species not detected, significant limits will be determined.
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