Magnetic Fields, Atmospheres, and the Connection to Habitability (MACH)

Is a global magnetic field required for a planet to retain an atmosphere or be habitable at its surface? This question is relevant for the history of climate evolution in our own solar system, and for evaluation of exoplanet habitability. Answering the question requires expertise from a diverse set of communities, some of which have diverged from each other over the past several decades. For example, modelers and observers of the terrestrial magnetosphere have limited overlap and interaction with modelers and observers of unmagnetized planets or the giant planets in our solar system. There is relatively limited interaction between any of the above communities and those who study exoplanets, though efforts have recently been increasing, as demonstrated by this meeting, to bridge the solar system and exoplanet communities. This presentation will describe recent progress toward determining whether planetary magnetic fields are critical component of their habitability, with emphasis on the activities of a newly-formed NASA Heliophysics DRIVE Science Center. This Center, named MACH (Magnetic Fields, Atmospheres, and the Connection to Habitability) includes representatives from multiple sub-disciplines in Heliophysics, Planetary Science, and Astrophysics (including exoplanets). Over the next several years the Center will support activities related to analysis of spacecraft observations of planetary plasma interactions, modeling of the interaction of planetary atmospheres and magnetic fields with their space environment, and the construction of a theoretical framework for atmospheric escape and habitability that includes both magnetized and unmagnetized planets. The MACH team has already made progress in comparing the atmospheric loss rates from Venus, Earth, and Mars in a consistent manner, and in extending models for atmospheric ion loss from Mars and Venus to Earth-strength fields. An overarching goal for the Center is to provide a web tool for the entire community that provides atmospheric loss rates as a function of planetary properties, stellar properties, and planetary magnetic field strength. The MACH Center will host a community-wide workshop in 2021 centered around this topic, and is seeking to grow their interactions with interested scientists from relevant disciplines.