MARSIS Transient Layer Detections during Comet Siding Spring Event 2014

The data contained in this file are measurements from the Mars Express spacecraft's MARSIS instrument, collected during the Comet Siding Spring flyby event in 2014. The comet is known to have deposited a large amount of material into Mars' ionosphere, producing a transient layer of plasma that was noticed by multiple spacecraft instruments immediately following the comet's closest approach to the planet. The layer was originally thought to have had a lifetime of 1-2 days. Follow-up analysis, represented in this data file, indicate that this layer could have lasted at least 7 days and as many as 32 days after closest approach, much longer than previously reported. Our results help to constrain models of metal ion chemistry in the Martian upper atmosphere.