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2004 Annual Science Report

NASA Goddard Space Flight Center Reporting  |  JUL 2003 – JUN 2004

Investigation of the Composition of Comet 2P/Encke at Infrared Wavelengths

4 Institutions
3 Teams
0 Publications
0 Field Sites
Field Sites

Project Progress

Comet 2P/Encke . M. Mumma, M. DiSanti, N. Dello Russo, B. Bonev, K. Magee-Sauer, and E. Gibb investigated the composition of comet 2P/Encke at infrared wavelengths. Six nights of observing time was awarded at the NASA Infrared Telescope Facility and the W.M. Keck Observatory in November, 2003, for this Jupiter-family comet of probable Kuiper-belt origin. Long-slit spectra from the facility instruments CSHELL (Infrared Telescope Facility (IRTF)) and NIRSPEC (Keck) featured both high spectral dispersion and high spatial resolution about the nucleus. H2O, C2H6 , CH3 OH, HCN, and C2H2 were detected (the symmetric hydrocarbons for the first time in Encke), and production rates and rotational temperatures were determined. Rotational analysis of H2O and C2H6 suggested very cold rotational distributions for coma gases (T rot ~ 20 — 30K). Relative abundances for C2H6 , CH3OH, HCN, and C2H2 with respect to water were close to those typically seen in Oort cloud comets, while the abundance of hypervolatile CH 4 was severely depleted. This represents the most detailed study of a comet of probable Kuiper-belt origin with high-resolution ground-based infrared spectroscopy, and serves as a model for future studies of faint comets.

    Objective 3.1
    Sources of prebiotic materials and catalysts