Simultaneous study of SWCX at Mars near solar maximum with XMM and Mars Express

We propose to utilize the exceptionally favorable observing conditions of Marsfor XMM in June 2014 for detailed studies of solar wind charge exchange (SWCX)induced Xray emission in its exosphere, accompanied by simultaneous insitumeasurements of the solar wind with Mars Express. XMM has already provided thefirst direct, unambiguous detection of SWCX emission from the Martian exosphere.This finding has consequences for Xray astrophysics in general (soft Xraybackground), is important for our understanding of planetary evolution(atmospheric outgassing), and opens up a novel method for remote global imagingof planetary exospheres and their spatial and temporal variability. There willbe no similarly favorable opportunity before 2023. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]