Solar Wind Corotating Interaction
Regions at Mars: Investigating
Sun-Mars Connections, 15-9524
Principal Investigators
Kurt Retherford
Nathan Schwadron
Joey Mukherjee
Geoff Crowley
Rudy Frahm
Inclusive Dates: 12/01/04 – 03/20/05
Background - Where did the water on Mars go? This question has great significance to the possibility for life on Mars at some point in its history. Water and other volatiles such as CO2 were at one point much more prevalent in Mars' atmosphere, which was likely greenhouse warmed to temperatures that allowed liquid water to flow on its surface. How much water was lost by escape to space versus lost by condensation and surface chemistry? A comprehensive understanding of the solar wind interaction with the Martian atmosphere is required to understand atmospheric loss to space. In this study, we investigated the presence and effects of a specific solar wind feature called a Corotating Interaction Region (CIR). This study utilized data obtained with the Electron Analyzer (ELS) instrument built by the Institute as part of the Analyzer of Space Plasma and Energetic Atoms (ASPERA-3) package aboard the European Space Agency's (ESAs) Mars Express (MEX) mission, which is currently operating at Mars.
Approach - Data mining techniques were used to find MEX/ASPERA-3/ELS measurements of the solar wind, when outside of the bow shock. Times of bow shock crossings were calculated based on standard formulas for the average bow shock location. Orbit-averaged electron density measurements from these MEX solar wind data were then calculated. A time series of such measurements was used to search for density peaks at the approximate 26 day CIR rotation period. Ulysses/SWOOPS core electron data products were also obtained for comparison with the time series data and identification of CIR features. A similar data search was conducted to find times when ELS ionosphere measurements were performed.
Accomplishments - We analyzed solar wind measurements obtained by MEX/ASPERA-3/ELS and successfully discovered signatures of CIRs in the solar wind at Mars. This step is the necessary first one in our search for solar wind-induced variability and outflows in the Mars ionosphere. Determining the proper format of data returned from this type of data search was more time consuming than originally planned. A comparison between solar wind density and ionospheric electron intensity was too preliminary to provide new results.
