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[1] We study the effect of the magnetosonic Mach number on the position of the bow shock (BS) at Mars. The magnetosonic Mach number is calculated from solar wind data obtained by the ACE satellite upstream of Earth and extrapolated to Mars during two intervals, starting in 2005 and 2007, when Mars and Earth were close to opposition. An increased Mach number is observed to cause the Martian BS to move to lower altitudes and the variation in the terminator altitude is proportional to the Mach number change. When the Mach number is lowered, the BS flares more. We also compare our results to previous studies at Venus. The variation in BS altitude with magnetosonic Mach number is found to be very similar to the variation of the Venusian BS, which has previously been shown to decrease linearly in altitude with increasing Mach number.

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The Emirates Mars Mission (EMM) – Hope Probe – was developed to understand Mars atmospheric circulation, dynamics, and processes through characterization of the Mars atmosphere layers and its interconnections enabled by a unique high-altitude (19,970 km periapse and 42,650 km apoapse) low inclination orbit that will offer an unprecedented local and seasonal time coverage over most of the planet. EMM has three scientific objectives to (A) characterize the state of the Martian lower atmosphere on global scales and its geographic, diurnal and seasonal variability, (B) correlate rates of thermal and photochemical atmospheric escape with conditions in the collisional Martian atmosphere, and (C) characterize the spatial structure and variability of key constituents in the Martian exosphere. The EMM data products include a variety of spectral and imaging data from three scientific instruments measuring Mars at visible, ultraviolet, and infrared wavelengths and contemporaneously and globally sampled on both diurnal and seasonal timescale. Here, we describe our strategies for addressing each objective with these data in addition to the complementary science data, tools, and physical models that will facilitate our understanding. The results will also fill a unique role by providing diagnostics of the physical processes driving atmospheric structure and dynamics, the connections between the lower and upper atmospheres, and the influences of these on atmospheric escape.