Structural and Compositional Changes in the Upper Atmosphere Related to the PEDE-2018 Dust Event on Mars as Observed by MAVEN NGIMS

The onset of the planet encircling dust event (PEDE-2018) started around 1 June 2018 as observed by Mars Reconnaissance Orbiter/Mars Color Imager, peaking around 7-10 July and persisting through mid-October 2018. After the onset of the event, the upper atmosphere underwent significant changes in density and thermal structures. Mars Atmosphere and Volatile Evolution-Neutral Gas and Ion Mass Spectrometer (MAVEN NGIMS) had a good opportunity to observe these changes from the first detection in the upper atmosphere and throughout the duration of the PEDE. The compositional changes included increased density at a constant altitude for CO₂ and Ar, while the O decreased from the peak throughout the decay of the bulk of the PEDE.