LASP Science Seminars
What Are Induced Magnetospheres and Do They Protect Planetary Atmospheres from Stellar Winds?
Robin Ramstad (LASP)
How is solar wind energy transferred to the ionosphere in an induced magnetosphere? Does more energy always facilitate faster escape of a planet’s atmosphere to space? These are questions I want to answer in order to understand how the solar wind has affected the atmospheric evolution of non-magnetized planets like Mars and Venus – and by comparison, whether Earth’s intrinsic magnetic dynamo really protects our atmosphere. I will give a condensed overview of the drivers of atmospheric ion escape at the three planets, as revealed over decades by a host of spacecraft missions and studies, and present what I think is the fundamental factor limiting the ion escape rate at each planet, respectively. Ultimately, the comprehensive measurements from the LASP-led Mars Atmosphere and Volatile EvolutioN (MAVEN) mission have revealed perhaps the most detailed picture so far of how solar wind power is transferred to the Martian ionosphere through the induced currents that shape the induced magnetosphere. A comparison with ion flux measurements from MAVEN preliminarily indicates that the Martian system can change its limited state in response to the upstream drivers, potentially revealing a fundamental property of atmospheric ion escape as a process at any planet with an atmosphere.