Cover Page/Proposal Summary

ROSS-99    NRA 99-OSS-01

Date Due: 5/3/99

We propose to explore the consequences of interplanetary dust impacting the atmospheres of Venus and Mars. Quantitative models will be developed to characterize the underlaying processes which control the transformation of infalling particulates into metallic ion and neutral particle layers and their subsequent spatial distribution. The deposition of these particles into the atmospheres of Mars and Venus will affect the plasma and neutral atmosphere environments of these planets in ways distinctly different from the Earth. A steady state 1-D model for Mars was recently developed that focused solely on the species Mg (Pesnell and Grebowsky,1999). This model will be used as the framework to study all species and will be enhanced to include time variations. The dependence on time is needed to study the effects of meteor showers, which are predicted to be more prevalent at Mars than Earth, and to treat local time variations. The latter needs to be included in any realistic model due to the local time asymmetries in the incident dust flux and to the rotation of the atmosphere with the planet. The refined model will be then be extended to Venusian conditions to explore the influence of its slow rotation and dense atmosphere. Measurements of the interactions of cosmic particles with different planetary atmospheres may eventually be a part of planetary missions because of their interesting physics and their ability to shed light on the properties of the interplanetary particle populations. They are integral parts of all planetary ionospheres. Much of our knowledge of these particles have been deduced from the interactions with the terrestrial atmosphere. Understanding of the Venus and Mars environments will provide us with two more potential laboratories in the inner solar system.