SPRG Seminars

August 26, 2008:

"What we learn from energetic neutral atom images of planetary magnetospheres at Mars"

Dr. Ed Roelof, Applied Physics Laboratory, Johns Hopkins University

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We now have years of ENA images from IMAGE/HENA in orbit around Earth during the last solar maximum and from CASSINI/INCA in orbit around Saturn since 2004.  These images reveal the behavior of ~20-200keV magnetospheric H+ and O+ ions with time resolution of as little as a few minutes.  Much has been learned from causality (what happened when and where), but there is also quantitative information that can be extracted from these ENA images.  In particular, they have transformed our understanding of pressure-driven current systems that play a key role in magnetosphere/ionosphere coupling.