DPS Pasadena Meeting 2000, 23-27 October 2000
Session 22. Titan II
Oral, Chairs: M. Mendillo, A. Coustenis, Tuesday, 2000/10/24, 1:30-2:20pm, Little Theater (C107)

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[22.04] Effect of Negative Ions on the Conductivity of Titan's Lower Atmosphere

W. J. Borucki (NASA Ames Research Center), E. L. Bakes (SETI Institute), R. C. Whitten (Raytheon Corp.)

In an earlier paper, Borucki et al (1987) calculated the electrical conductivity and electrical charge on aerosols in Titanís atmosphere due to the ionization by galactic cosmic rays and electron precipitation from Saturnís magnetosphere. The lower atmosphere was predicted to be substantially more conducting than the atmospheres of Earth and Venus because of the high concentration of free electrons. The prediction of a high conductivity is based on the lack of electrophillic species which form negative ions with low mobility and which reduce the number of free electrons. At that time, no molecular species capable of forming negative ions in concentrations sufficient to perturb the atmospheric conductivity were identified. Recently, E. Bakes and her colleagues have been investigating the formation of nitrogenous macromolecules using quantum mechanical methods. Their calculations indicate that the molecules will be highly electrophillic and are likely to be present in the atmosphere at mixing ratios of order 10-7. This mixing ratio is sufficiently large that a substantial reduction in the conductivity is expected at altitudes below 100 km. Revision of the atmospheric model to accommodate the presence of negative ions and to increase the fidelity of the modeling will be described.

Borucki, W. J., Z. Levin, R.C.Whitten, R.G. Keesee, L.A. Capone, A.L. Summers, O.B. Toon, and J. Dubach. Predictions of the electrical conductivity and charging of the aerosols in Titanís atmosphere. Icarus 72, 604-622 (1987).

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