HR: 17:00h
AN: P14C-01    [Abstracts]
TI: Ion Composition measured in the environment of Comet 19P/Borrelly by Deep Space One
AU: * Reisenfeld, D B
EM: dan.reisenfeld@umontana.edu
AF: Department of Physics & Astronomy, University of Montana 32 Campus Dr, Missoula, MT 59812,
AU: Williams, J D
EM: john2.williams@umontana.edu
AF: Department of Physics & Astronomy, University of Montana 32 Campus Dr, Missoula, MT 59812,
AU: Jessop, A
EM: amberjessop@hotmail.com
AF: Department of Physics & Astronomy, University of Montana 32 Campus Dr, Missoula, MT 59812,
AU: Janzen, P H
EM: pjanzen@lanl.gov
AF: ISR-1, Los Alamos National Laboratory P.O. Box 1663, MS-D446, Los Alamos, NM 87545,
AU: Harper, R
EM: rharper@lanl.gov
AF: ISR-1, Los Alamos National Laboratory P.O. Box 1663, MS-D446, Los Alamos, NM 87545,
AB: We report in situ ion mass spectrometer (PEPE) measurements from the coma of Comet 19P/Borrelly, obtained during the flyby of the Deep Space One (DS1) spacecraft on 22 September 2001. The DS1 encounter with Borrelly is only the 4th encounter where the plasma environment of a comet has been sampled in situ, and this is the first encounter with a Jupiter family comet where a mass spectrometer was able to measure ions heavier than hydrogen. Cometary ions were detected at distances from ~ 5.5 × 10⁵ km to 2200 km from the nucleus of the comet. Previously, ion composition measurements by the PEPE instruments were reported at closest approach by Nordholt et al. (2003), where it was shown that the water group ion distribution was quite different from Comet Halley observations and cometary models. Of particular note is the small amount of H₃O⁺ (< 9%), as this was the most abundant molecular ion observed at closest approach to Halley. Here, we refine and extend that work and report on the cometary ion composition as a function of distance from the comet. The key advance in our analysis capability arises from a thorough calibration of the PEPE flight spare over a range of atomic and molecular species relevant to cometary composition.
DE: 1060 Planetary geochemistry (5405, 5410, 5704, 5709, 6005, 6008)
DE: 6025 Interactions with solar wind plasma and fields
DE: 6050 Plasma and MHD instabilities (2149, 2752, 7836)
DE: 6210 Comets (6023)
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting