A model of the martian ionosphere below 70 km

Abstract The ion-neutral chemistry of the atmosphere of Mars has been studied with a one-dimensional model. Here we present the main reactions that lead to the formation of the most abundant positive and negative ions. Galactic cosmic rays ionize the atmospheric constituents, mainly CO 2 , and reactions of charge transfer of CO + 2 with oxygen produces O + 2 . The further ion-neutral chemistry is quite similar to that of D -region on Earth. The relative high abundance of water and its higher proton affinity compared with other molecules, lead to the expectation that the most abundant positive ions are hydronium hydrates, H + 3 O(H 2 O) n . The chemistry includes the production of negative ions, O − and O − 2 , by electron capture of oxygen-bearing molecules and sinks of negative ions by electron photodetachment and ion-ion recombination. Oxygen negative ions are transformed through a chain of reactions into the carbon and nitrogen-bearing ions, CO − n and NO − n . The formation of hydrated negative ions is also considered.

[1]  R. Rodrigo,et al.  A nonsteady one‐dimensional theoretical model of Mars' neutral atmospheric composition between 30 and 200 km , 1990 .

[2]  C. Winchester,et al.  Numerical models of the Martian coupled thermosphere and ionosphere , 1995 .

[3]  K. O'brien.  Cosmic-ray propagation in the atmosphere , 1971 .

[4]  R. W. Schunk,et al.  Solar-terrestrial energy program : handbook of ionospheric models , 1996 .

[5]  S. Haider.  Chemistry of the nightside ionosphere of Mars , 1997 .

[6]  K. O'brien.  PROPAGATION OF MUONS UNDERGROUND AND THE PRIMARY COSMIC-RAY SPECTRUM BELOW 40 TeV. , 1972 .

[7]  A. Anbar,et al.  A photochemical model of the martian atmosphere. , 1994, Icarus.

[8]  L. Lara,et al.  Ionization by cosmic rays of the atmosphere of Titan , 1999 .

[9]  D. R. Rushneck,et al.  The composition of the atmosphere at the surface of Mars , 1977 .

[10]  W. B. Hanson,et al.  The Martian ionosphere as observed by the Viking retarding potential analyzers , 1977 .

[11]  M. Charlton,et al.  Non-dissociative and dissociative ionization of N 2 , CO, CO 2 , and CH 4 by impact of 50-6000 keV protons and antiprotons , 1995 .

[12]  James S. Sims,et al.  The ionosphere of mars below 80 km altitude—I quiescent conditions , 1971 .

[13]  E. Kopp,et al.  Model calculations of the negative ion chemistry in the mesosphere with special emphasis on the chlorine species and the formation of cluster ions , 1998 .

[14]  E. Arijs.  Stratospheric ion chemistry: Present understanding and outstanding problems , 1992 .

[15]  J. Mitchell.  The dissociative recombination of molecular ions , 1990 .

[16]  D. Edwards,et al.  Non‐local thermodynamic equilibrium in general circulation models of the Martian atmosphere 1. Effects of the local thermodynamic equilibrium approximation on thermal cooling and solar heating , 1998 .

[17]  T. Tohmatsu.  Compendium of Aeronomy , 1990 .

[18]  K O'Brien,et al.  Atmospheric cosmic rays and solar energetic particles at aircraft altitudes. , 1996, Environment international.

[19]  K. O'brien,et al.  The distribution in energy and angle of high-energy neutrons from a gun source , 1968 .

[20]  K. O'brien.  Extra-nuclear hadron cascade calculations using Passow's approximation , 1969 .

[21]  E. Ferguson.  D‐region ion chemistry , 1971 .

[22]  R. Whitten,et al.  The ionosphere of Mars below 80 km altitude. II - Solar cosmic ray event , 1971 .

[23]  P. Kemper.  Gas phase ion—molecule reaction rate constants through 1986 , 1988 .