HR: 1340h
AN: SA53B-1171    [Abstracts]
TI: Water Chemistry in Cometary Comae
AU: * Boice, D C
EM: DBoice@swri.edu
AF: Southwest Research Institute, Space Science & Engineering Div., 6220 Culebra Road, San Antonio, TX 78238-5166 United States
AB: Water chemistry is central in understanding the physics and chemistry of cometary comae. A rather advanced knowledge of water chemistry has been attained from studies of various comets via ground-based observations and in situ spacecraft measurements, especially the Giotto encounter with comet 1P/Halley. Photochemistry and the effects of photoelectrons that react via electron impact reactions, ion-molecule reactions, and the interaction with solar wind plasma are important processes that affect the overall composition and ionization state in the coma. However, initial results from the PEPE instrument onboard Deep Space 1 (DS1) concerning water-group ions around closest approach significantly differ from those expected from model results, challenging conventional notions. We have attempted to reconcile these differences in ion composition between the DS1 in situ measurements and model results with an extensive modeling investigation, unique from previous studies. This work should be relevant to past, on-going, and future spacecraft missions to comets.
DE: 6005 Atmospheres (1060)
DE: 6008 Composition (1060)
DE: 6025 Interactions with solar wind plasma and fields
DE: 6050 Plasma and MHD instabilities (2149, 2752, 7836)
DE: 6210 Comets (6023)
SC: SPA-Aeronomy [SA]
MN: Fall Meeting 2005