Comet Siding Spring's Impact on the Martian Magnetosphere: Observations from MAVEN's magnetometer

Thursday, 18 December 2014
Jared R Espley, Goddard Space Flight Center, Greenbelt, MD, United States, John E P Connerney, NASA Goddard Space Flight Center, Greenbelt, MD, United States, Gina A DiBraccio, NASA Goddard Space Flight Center, Solar System Exploration Division, Greenbelt, MD, United States and Bruce Martin Jakosky, Laboratory for Atmospheric and Space Physics, Boulder, CO, United States
Comet C/2013 A1 (Siding Spring) will pass within approximately 130,000 km of Mars on Oct. 19th, 2014. This means that Mars will be enveloped by the outer parts of the cometary coma which consists of neutral gases, mostly water and associated molecules. Some percentage of this gas is being continually ionized thus creating a cometary ion tail which will also intersect with Mars. The amount of gas and plasma interacting with Mars depends on the production rate of gas as it sublimates from the cometary nucleus (the cometary “activity”). This activity is still uncertain but based on the most recent observations it is plausible that the amount of inflowing plasma will be temporarily comparable to the amount from a large solar storm. This means that the martian induced magnetosphere will be significantly distorted from its baseline configuration. It also means that the inflowing cometary plasma will temporarily enhance the atmospheric escape from the martian atmosphere. We will present observations by the magnetometer on MAVEN during the comet’s passage and discuss the physical implications of the observations for the comet’s effect on the martian magnetosphere.