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Session 27 - Planets.
Oral session, Wednesday, January 07

[27.03] Meteoric Ionization Layers in the Martian Atmosphere

W. D. Pesnell (Nomad Research, Inc.), J. M. Grebowsky (NASA/GSFC)

Mars, like the other planets, is bombarded by meteorites. At least two families of particles impact the planets: sporadic and shower. In the terrestrial atmosphere both families cause sporadic-E layers when the introduced material is ionized by charge-exchange, photoionization, or impact ionization. Narrow layers of ionized material are produced when the long-lived metallic ions are compressed by tidal or gravity wave motions in the atmosphere. We will examine how the ion-neutral chemistry and dynamics of the Martian atmosphere affect the deposited meteoric material. Our emphasis is on magnesium, an easily ionized species that is a major component of the meteoric debris. The parameters that affect the meteoric ionization differ between Earth and Mars. In particular, the atmospheric compositions and ionospheric densities differ. Further, the lower atmospheric pressure on Mars means lower altitudes for the bulk of the atmospheric ablation of the meteorites. However, the range of atmospheric density variation at high altitudes is greater at Mars than at Earth, so that sputtering of high speed shower streams which occurs at high altitudes may be relatively more important at Mars than Earth.

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