Martian Atmospheric Loss Through Foreshock Transient Events

Abstract At Mars, the MAVEN spacecraft has made observations of Hot Flow Anomalies (HFAs) in the foreshock. Due to the bow shock's proximity to the planet, it is theorized that HFAs contribute to atmospheric escape at Mars through the excavation of ionospheric ions. A case study investigates one HFA observation, with parameters suggesting a novel mechanism for planetary ion extraction. The event is further characterized by elevated number densities of and ions observed prior to the current sheet crossing. Statistical study is conducted on a set of 91 events, facilitating the estimation of HFA frequency at Mars to be 1/day. The estimated ion escape of the event is approximately 9 of the typical ion escape rate under nominal conditions at Mars. Calculation of further events reveals escape rates between 1 and 9 of the nominal conditions. This represents a modest contribution to the overall escape, highlighting a potentially underexplored pathway.