Numerical simulation of the effects of meteoroid ablation and solar EUV/X-ray radiation in the dayside ionosphere of Mars: MGS/MEX observations

Abstract

We have developed a model which produces three plasma layers simultaneously due to the impact of the meteoroids, solar X-ray (0.5–9 nm), and EUV (9–102.6 nm) radiation at altitude range 75–85 km, 100–115 km, and 135–140 km, respectively, in the dayside ionosphere of Mars. The calculated results are compared with the radio occultation measurements made by Mars Express (MEX) and Mars Global Surveyor (MGS) on 18 April 2004 and 11 May 2005, when comets P/2003 WC7 (LINEAR Catalina) and 10P/Tempel 2 intersected the orbit of Mars, respectively. The densities of 21 ions (CO₂⁺, O₂⁺, CO⁺, O⁺, NO⁺, N₂⁺, Mg⁺, Fe⁺, Si⁺, MgO⁺, FeO⁺, SiO⁺, MgCO₂⁺, MgO₂⁺, FeCO₂⁺, FeO₂⁺, SiCO₂⁺, SiO₂⁺, MgN₂⁺, FeN₂⁺, and SiN₂⁺) and 10 neutral species (Mg, Fe, Si, MgO, FeO, SiO, MgCO₃, FeCO₃, MgO₂, and FeO₂) have been computed self-consistently for both days. The metallic ions are formed in the middle ionosphere due to the ablation of meteoroids. It is found that the middle ionosphere of Mars strongly depends on incoming mass and flux of the meteoroids. The meteoroids of fluxes 4.0 × 10⁻¹⁵ and 8.3 × 10⁻¹⁶ cm⁻² s⁻¹ for masses 4.5 × 10⁻⁷ g and 1.0 × 10⁻³ g have produced third layers, which are good in agreement with the observations made by MEX and MGS on 18 April 2004 and 11 May 2005, respectively.