HR: 11:50h
AN: SA12A-07 INVITED     [Abstracts]
TI: Solar Wind Interactions with Planetary Atmospheres
AU: * Brecht, S H
EM: sbrecht@pacbell.net
AF: Stephen H. Brecht, Bay Area Research Corp., Orinda, CA 94563 United States
AB: When considering the issue of life on Mars, a variety of issues come to mind. One of them is the evolution of the atmosphere of the planet. Planets with an intrinsic magnetic field are protected for the most part from the solar wind, leaving just the solar radiation flux as method for modifying the atmospheric and ionospheric chemistry. In the case of Mars, there is no planet wide magnetic field. There are conjectures that at one time Mars did indeed have a significant magnetic field. If it did the dynamo has long since died. This situation means that the atmosphere/ionosphere of Mars is in direct contact with solar wind plasma and fields. Further, the bow shock of Mars does not protect it very well from incoming energetic particles. This situation means that unlike Earth, Mars loses it ionosphere/atmosphere by scavenging via electric fields from the solar wind. Further, the ionosphere/atmosphere also experiences an additional source of energy/heat. Simulations have shown that the deposition energy can approach and in some cases exceed that of the solar EUV flux. Thus the atmosphere is subject heating even on the night side because of the large ion gyroradius. In this talk the physics of this situation will be discussed. It will be coupled with the idea that Mars may have lost it's water via the atmospheric loss mechanism driven by the solar wind interactions. The consequences for life are subject to conjecture, but it is clear that these enhanced loses and heating had a profound affect on the atmosphere/ionosphere of Mars.
DE: 5407 Atmospheres--evolution
DE: 5421 Interactions with particles and fields
DE: 6225 Mars
SC: SPA-Aeronomy [SA]
MN: 2004 AGU Fall Meeting