Solar cycle effects on the ion escape from Mars

Abstract

Solar cycle effects on the escape of planetary ions from Mars are investigated using Mars Express Analyzer of Space Plasmas and Energetic Atoms 3 data from June 2007 to January 2013. Average and median tail fluxes of low‐energy (<300 eV) heavy ions (O+, O2+), derived from the full data set covering 7900 orbits, are highly correlated with the solar activity proxies F10.7 and the sunspot number, Ri. The average heavy ion escape rate increased by a factor of ≈ 10, from ≈ 1 · 1024 s−1 (solar minimum) to ≈ 1 · 1025 s−1 (solar maximum). Combining data from this, and other studies, an empiric model/expression is derived for the Martian escape rate versus solar activity F10.7 and Ri. The model is a useful tool to derive the accumulated ion escape rate from Mars based on historical records of solar activity, with potentials back to the young Sun époque.