MAVEN IUVS Observations of the Aftermath of the Comet Siding Spring Meteor Shower on Mars

Abstract : We report the detection of intense emission from magnesium ions in Mars' atmosphere caused by a meteor shower following Comet Siding Spring's close encounter with Mars. The observations were made with the Imaging Ultraviolet Spectrograph, a remote sensing instrument on the Mars Atmosphere and Volatile EvolutioN spacecraft orbiting Mars. Ionized magnesium caused the brightest emission from the planet's atmosphere for many hours, resulting from resonant scattering of solar ultraviolet light. Modeling suggests a substantial fluence of low-density dust particles 1–100 µm in size, with the large amount and small size contrary to predictions. The event created a temporary planet-wide ionospheric layer below Mars' main dayside ionosphere and above the persistent layer that exists due to sporadic meteors. These observations inform our understanding of the meteoric atmospheric chemistry and dynamical processes.