Observations of the Martian ionosphere by the Neutral Gas and Ion Mass Spectrometer During the First Year of the MAVEN Mission

Abstract:

We report the results of the observations of the ionosphere of Mars by the Neutral Gas and Ion Mass Spectrometer (NGIMS). These observations were conducted during the first year of the Mars Atmosphere and Volatile Evolution mission (MAVEN). These observations revealed the spatial and temporal structures in the density distributions of 22 ions: H₂⁺, H₃⁺, He⁺, O²⁺, C⁺, CH⁺, N⁺, NH⁺, O⁺, OH⁺, H₂O⁺, H₃O⁺, N₂⁺/CO⁺, HCO⁺/HOC⁺/N₂H⁺, NO⁺, HNO⁺, O₂⁺, HO₂⁺, Ar⁺, ArH⁺, CO₂⁺, and OCOH⁺. Dusk/dawn and day/night asymmetries in the density distributions were observed for nearly all ion species. The three MAVEN “deep-dip” campaigns were used to investigate the location of the primary ion peak. This peak was detected at a surprisingly high altitude (190 km) near the terminator, but was below the spacecraft altitude of 130 km near the subsolar point.