Comparative study of electron fluxes, ionization rates, ion and electron densities due to photoelectron and magnetospheric electron interaction with the atmosphere of Mars

Abstract

A comparative study of nighttime and daytime ionosphere of Mars has been made by calculating electron fluxes, ion production rates and ion and electron densities for the nightside and dayside ionosphere of Mars. For the calculation of nightside ionospheric study we have used the primary electron spectrs measured by HARP experiment onboard the PHOBOS-2 martian orbiter. Calculations for monoenergetic (unit flux) ion production rates in the nightside have also been carried out. Analytical yield spectrum approach and coupled continuity equations for chemical steady-state conditions have been used to carry out this calculation. The electron densities calculated for daytime and nighttime are compared with the data of Viking 1 and 2 radio occulations respectively. It is found that the energy of electron spectra (few hundred eV) observed by HARP experiment in martian magnetosphere is sufficient for i,pact ionization of planetary neutral gas and characteristic flux could produce the nightside ionospheric layer with a peak density of a few thousands of electrons per cubic centimeter, which corresponds to densities earlier observed by the radio occultation experiment of Viking 2. The electron density for nighttime is found to be 20 times less than that of daytime and peaks at 30 km above the daytime ionosphere.