MOSAIC: A satellite constellation to enable groundbreaking Mars climate system science and prepare for human exploration.

The Martian climate system has been revealed to be at least as complex as Earth’s. Over the last 20 years a fragmented and incomplete picture has emerged of its structure and variability; we remain largely ignorant of many of the physical processes that drive matter and energy flow between and within Mars’ diverse climate domains. Mars Orbiters for Surface, Atmosphere, and Ionosphere Connections (MOSAIC) is a constellation of ten platforms focused on understanding these climate connections, with orbits and instruments tailored to observe the Mars climate system from three complementary perspectives. First, low circular near-polar sun-synchronous orbits (a large mothership and three smallsats spaced in local time) enable vertical profiling of wind, aerosols, water and temperature, as well as mapping of surface and subsurface ice. Second, elliptical orbits sampling all of Mars’ plasma regions enable multi-point measurements necessary to understand mass/energy transport and ion-driven escape. Last, longitudinally-spaced areostationary orbits enable a) synoptic views of the lower atmosphere necessary to understand global and mesoscale dynamics, b) global views of the hydrogen and oxygen exospheres, and c) upstream measurements of space weather conditions. Motivated by well-established Decadal Survey and Mars Exploration Program Analysis Group (MEPAG) goals, MOSAIC will characterize climate system variability diurnally and seasonally, on meso-, regional, and global scales, targeting the shallow subsurface all the way out to the solar wind, making many first-of-their-kind measurements. Importantly, these measurements will also prepare for human exploration and settlement of Mars by providing valuable water resource prospecting and the forecasting of dust and radiation hazards and ionospheric communication/positioning disruptions.