Analysis of the Martian atmosphere for riometry

The riometer (relative ionospheric opacity meter) technique for measuring changes in the electron density of the atmosphere is useful for investigating the effects of precipitating electron fluxes, as well as those of solar photoionization and solar and galactic cosmic rays. The efficacy of extending the riometer method to the Martian ionosphere is examined, and it is found that characteristics of the Martian atmosphere make it more sensitive than the terrestrial atmosphere to riometer absorption by several orders of magnitude for the same incident electron spectrum. The increased sensitivity is due both to the lower altitudes that energetic electrons can attain in the thinner Martian atmosphere, as well as to the enhanced effects of electron-neutral collisions with Martian carbon dioxide molecules versus terrestrial nitrogen molecules (these gases are the major atmospheric constituents at altitudes sensitive to riometer measurements in the respective atmospheres). Even though the Martian environment does not have magnetospheric regions capable of trapping and accelerating solar wind electrons, this enhanced sensitivity may make it possible to examine effects of the solar wind on the atmosphere that can only be examined on Earth within the narrow boundaries of the auroral oval and geomagnetic cusp/cleft regions.