Solar Ionizing Radiation at Mars: Predictions vs. MAVEN Observations

The primary source of energy in the Martian upper atmosphere is solar ionizing radiation. The first of the many processes that convert solar radiation to thermal energy is the production of photoelectrons. Observations on the MAVEN spacecraft of both photoelectrons and broad band solar ionizing radiation allow quantitative comparison of model calculations of the photoelectron energy spectra below 200 km with observations. We compare and contrast photoelectron energy spectra observed before and after an X class solar flare on October 19, 2014 with calculations from three photoelectron production and transport codes and solar irradiance spectra derived from both MAVEN and Earth based observations. We find good agreement between data and models