Influence of the solar EUV flux on the Martian plasma environment

Abstract. The interaction of the solar wind with the Martian atmosphere and ionosphere is investigated by using three-dimensional, global and multi-species hybrid simulations. In the present work we focus on the influence of the solar EUV flux on the Martian plasma environment by comparing simulations done for conditions representative of the extrema of the solar cycle. The dynamics of four ionic species (H+, He++, O+, O2+), originating either from the solar wind or from the planetary plasma, is treated fully kinetically in the simulation model in order to characterize the distribution of each component of the plasma, both at solar maximum and at solar minimum. The solar EUV flux controls the ionization frequencies of the exospheric species, atomic hydrogen and oxygen, as well as the density, the temperature, and thus the extension of the exosphere. Ionization by photons and by electron impacts, and the main charge exchange reactions are self-consistently included in the simulation model. Simulation results are in reasonable agreement with the observations made by Phobos-2 and Mars Global Surveyor (MGS) spacecraft: 1) the interaction creates a cavity, void of solar wind ions (H+, He++), which depends weakly upon the phase of the solar cycle, 2) the motional electric field of the solar wind flow creates strong asymmetries in the Martian environment, 3) the spatial distribution of the different components of the planetary plasma depends strongly upon the phase of the solar cycle. The fluxes of the escaping planetary ions are computed from the simulated data and results for solar maximum are compared with estimates based on the measurements made by experiments ASPERA and TAUS on board Phobos-2.

[1]  V. Thomas.  Dimensionality effects in hybrid simulations of high Mach number collisionless perpendicular shocks , 1989 .

[2]  V. A. Krasnopolsky,et al.  Photochemistry of the Martian Atmosphere (Mean Conditions) , 1993 .

[3]  C. Russell,et al.  The solar cycle dependence of the location and shape of the Venus bow shock , 1990 .

[4]  Clinton P. T. Groth,et al.  3D multi‐fluid MHD studies of the solar wind interaction with Mars , 1999 .

[5]  S. Barabash,et al.  On the momentum transfer of the solar wind to the Martian topside ionosphere , 1991 .

[6]  M. Acuna,et al.  Factors controlling the location of the Bow Shock at Mars , 2002 .

[7]  Igor V. Sokolov,et al.  Three‐dimensional, multispecies, high spatial resolution MHD studies of the solar wind interaction with Mars , 2004 .

[8]  Rickard N. Lundin,et al.  Aspera/Phobos measurements of the ion outflow from the MARTIAN ionosphere , 1990 .

[9]  R. Stebbings,et al.  Charge transfer between oxygen atoms and O+ and H+ ions , 1964 .

[10]  Kenneth G. Powell,et al.  Three-dimensional multispecies MHD studies of the solar wind interaction with Mars in the presence of crustal fields , 2002 .

[11]  K. Sauer,et al.  The Nature of the Martian `Obstacle Boundary' , 2000 .

[12]  R. Bruno,et al.  Selected solar wind parameters at 1 AU through two solar activity cycles , 1994 .

[13]  H. Shimazu.  Three-dimensional hybrid simulation of solar wind interaction with unmagnetized planets , 2001 .

[14]  J. Connerney,et al.  Magnetic field of Mars: Summary of results from the aerobraking and mapping orbits , 2001 .

[15]  H. Koskinen,et al.  Plasma composition measurements of the Martian magnetosphere morphology , 1990 .

[16]  K. Sauer,et al.  Multiple shocks near Mars , 1998 .

[17]  T. Tanaka,et al.  Configurations of the solar wind flow and magnetic field around the planets with no magnetic field : calculation by a new MHD simulation scheme , 1993 .

[18]  J. Slavin,et al.  Bow Shock and Upstream Phenomena at Mars , 2004 .

[19]  K. Sauer,et al.  Evidence of an ion composition boundary (protonopause) in bi‐ion fluid simulations of solar wind mass loading , 1994 .

[20]  Ness,et al.  Magnetic Field and Plasma Observations at Mars: Initial Results of the Mars Global Surveyor Mission , 1998, Science.

[21]  H. Lichtenegger,et al.  Model calculations of the planetary ion distribution in the Martian tail , 1998 .

[22]  K. Sauer,et al.  Bow shock ‘splitting’ in bi-ion flows , 1996 .

[23]  H. Hayakawa,et al.  Solar Wind-Induced Atmospheric Erosion at Mars: First Results from ASPERA-3 on Mars Express , 2004, Science.

[24]  D. Mccomas,et al.  Global hybrid simulation of the solar wind interaction with the dayside of Venus , 1991 .

[25]  A. Matthews,et al.  Current Advance Method and Cyclic Leapfrog for 2D Multispecies Hybrid Plasma Simulations , 1994 .

[26]  Dana Hurley Crider,et al.  The plasma Environment of Mars , 2004 .

[27]  C. Russell,et al.  Picked‐up protons near Mars: Phobos observations , 1991 .

[28]  Pekka Janhunen,et al.  Ion escape from Mars in a quasi‐neutral hybrid model , 2002 .

[29]  R. Hodges.  Distributions of hot oxygen for Venus and Mars , 2000 .

[30]  E. Kallio,et al.  Atmospheric effects of proton precipitation in the Martian atmosphere and its connection to the Mars‐solar wind interaction , 2001 .

[31]  Jhoon Kim,et al.  Solar cycle variability of hot oxygen atoms at Mars , 1998 .

[32]  R. Lundin,et al.  Structuring of the transition region (plasma mantle) of the Martian magnetosphere , 1996 .

[33]  H. Rosenbauer,et al.  Ions of planetary origin in the Martian magnetosphere (Phobos 2/Taus experiment) , 1991 .

[34]  S. Brecht.  Solar wind proton deposition into the Martian atmosphere , 1997 .

[35]  B. Hultqvist,et al.  First measurements of the ionospheric plasma escape from Mars , 1989, Nature.

[36]  David L. Mitchell,et al.  The solar wind interaction with Mars: Locations and shapes of the bow shock and the magnetic pile‐up boundary from the observations of the MAG/ER Experiment onboard Mars Global Surveyor , 2000 .

[37]  S. Brecht,et al.  Global hybrid simulation of unmagnetized planets: Comparison of Venus and Mars , 1991 .

[38]  H. Shimazu.  Three-dimensional hybrid simulation of magnetized plasma flow around an obstacle , 1999 .

[39]  G. Dunn.  Electron Impact Ionization , 2013, IEEE Transactions on Nuclear Science.

[40]  K. Powell,et al.  THE SOLAR WIND INTERACTION WITH MARS: RESULTS OF THREE-DIMENSIONAL MHD STUDIES , 2001 .

[41]  K. Powell,et al.  The solar wind interaction with Mars: results of three-dimensional three-species MHD studies , 2001 .

[42]  H. Koskinen,et al.  A test particle simulation of the motion of oxygen ions and solar wind protons near Mars , 1999 .