Mars Crustal Magnetism: Through The Lens Sharply  

By Dr. John E.P. Connerney, NASA Goddard Space Flight Center, USA

Abstract 
Mars has no global magnetic field of internal origin (a “dynamo”), but must have had one in the past when the crust acquired intense magnetization, presumably by cooling in the presence of an Earth-like magnetic field (thermoremanent magnetization or TRM). The Mars Global Surveyor (MGS) spacecraft, in polar orbit at ~400 km altitude, produced maps of the crustal magnetic field with extraordinary signal to noise. These maps yield valuable insight regarding crustal evolution on Mars, the role of plate tectonics, and a history of resurfacing by massive lava flows. We have utilized a new downward continuation technique (similar to Fourier methods commonly applied to survey data) to generate sharper images of crustal features. These new maps better reveal a magnetic imprint (in Meridiani) like that observed above a mid-ocean ridge on Earth. It may be a relic of an era of plate tectonics on Mars, characterized by crustal spreading, rifting, plate motions, and widespread volcanism following the demise of the dynamo. We present this Mars data in the context of the early development of plate tectonics on Earth, as advanced by the Vine-Matthews hypothesis and the work of W. Jason Morgan and others

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Dr. John Connerney is a space scientist at NASA’s GSFC. He is Deputy Principal Investigator (PI) for the Juno New Frontier mission to Jupiter, PI for Juno and MAVEN magnetometer investigations, Co-I on Voyagers 1&2, Mars Global Surveyor, etc.  He has published >100 scientific articles on geophysical inverse theory, planetary magnetic fields, radio emissions, ionospheres, aurorae, and the electrodynamic interaction of satellites and ring systems with a planetary magnetic field. He received a bachelor's and a doctorate in Applied and Engineering Physics from Cornell University. He is a Fellow of the American Geophysical Union and recipient of the John C. Lindsay Memorial Award for Space Sciences, the NASA Exceptional Scientific Achievement Award, and the NASA Medal for Exceptional Achievement.