P21A-2095
MAVEN Observations of Ionosphere Magnetization at Mars: Implications for Atmospheric Escape
Tuesday, 15 December 2015
Poster Hall (Moscone South)
Gina A DiBraccio1, Jared R Espley2, Jacob Gruesbeck3, John E P Connerney2, Yasir Ibn Jilani Soobiah2, Dave A Brain4, Jasper S Halekas5, David L Mitchell6, James P McFadden6, Christian Xavier Mazelle7, Marissa Vogt8, Yuki Harada9 and Takuya Hara9, (1)NASA Goddard Space Flight Center, Solar System Exploration Division, Greenbelt, MD, United States, (2)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (3)University of Maryland College Park, College Park, MD, United States, (4)University of Colorado at Boulder, Laboratory for Atmospheric and Space Physics, Boulder, CO, United States, (5)University of Iowa, Physics and Astronomy, Iowa City, IA, United States, (6)University of California Berkeley, Berkeley, CA, United States, (7)University Paul Sabatier Toulouse III, Toulouse Cedex 09, France, (8)Boston University, Boston, MA, United States, (9)Space Sciences Laboratory, Berkeley, CA, United States
Abstract:
We investigate the complex coupling between the Martian ionosphere and magnetosphere, formed as the solar wind interacts with the planet's upper atmosphere and localized crustal magnetic fields. Data from MAVEN's Particles and Fields Package are analyzed to assess variations in the magnetic structure of the ionosphere and possible links to particle transport within, and away from, the ionosphere. During periods when incident solar wind dynamic pressure exceeds ionospheric plasma pressure, the ionosphere of Mars may become strongly magnetized. At Venus, these periods of intense ionosphere magnetization were reported to suppress the formation of ionospheric flux ropes, helical magnetic structures that are also observed at Mars. Magnetic flux ropes may serve as a gateway for plasma exchange between the ionosphere and the magnetosheath, while heavily draped, horizontal ionospheric fields would inhibit vertical transport. Therefore, changes in the Martian ionospheric structure, based on varying upstream conditions, may have implications for particle transport mechanisms leading to atmospheric escape. Here, we examine magnetic field and plasma characteristics as a function of altitude and latitude in order to characterize several features of the Martian ionosphere-magnetosphere coupling: 1) the degree to which the ionosphere becomes magnetized; 2) whether ionospheric flux rope formation is enhanced or impeded, based on upstream solar wind conditions; and 3) possible implications of ionosphere magnetization on atmospheric escape. By constraining these characteristics we can better understand the Mars-solar wind interaction and, more specifically, how the magnetic structure of the ionosphere may affect particle transport and atmospheric escape.
