DPS 35th Meeting, 1-6 September 2003
Session 38. Comets V
Poster, Highlighted on, Friday, September 5, 2003, 3:30-6:00pm, Sierra Ballroom I-II

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[38.03] Investigation of the Comet Nucleus-Coma Boundary Layer

R. Link (Algoma Research, Inc.), W.F. Huebner (Southwest Research Institute)

The MIRO instrument (Gulkis et al., 2000) to be flown on the Rosetta mission will investigate the boundary layer of comet 46P/Wirtanen at the nucleus - coma interface through measurements of the lineshapes of important cometary species (H2O, CO, CH3OH, NH3) in the frequency range 552 - 580 GHz. The MIRO spectrometer is ideally suited to measure the line profiles due to Doppler shifts of the evaporating and effusing gases in the line of sight to the comet nucleus. In anticipation of these measurements, we are developing a fully-kinetic model of the velocity distribution of the non-thermal gases escaping from the nucleus into the Knudsen (boundary) layer. Our approach is to solve the non-linear Boltzmann transport equation accounting for self-collisions of the major gases. Transformation of the collisions from the center-of-mass system to the laboratory frame results in an angular scattering phase function, which is solved through a delta-Eddington expansion of the phase function moments. This report updates our progress with the model.

This research is supported by the NASA Planetary Atmospheres Program (NAG5-11052).

The author(s) of this abstract have provided an email address for comments about the abstract: rocketscientist82@yahoo.com

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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.