[PLS] Isaac Narrett (MIT)

“Magnetism of the Moon and Mercury”

Measurements of remanent magnetic fields can provide insight into planetary interiors and evolution, but their interpretation is often complicated by underdetermined magnetizing field intensities and crustal composition. In this talk, I will present work reducing these uncertainties to better explain the crustal magnetic field records of the Moon and Mercury and show how they can provide information on each body’s dynamo history and evolution. I will first demonstrate how the Moon’s and Mercury’s ancient crustal magnetic records could have been acquired when a weak dynamo field was amplified by impact-generated plasma. The feasibility of this mechanism allows us to explain the strongest measured crustal fields of the Moon and some components of Mercury’s remanent fields (but not all!). I will then revisit the unexplained components of Mercury’s remanent magnetization by coupling magnetohydrodynamic simulations of the ancient solar wind interaction with the planetary field to thermal cooling and magnetization models. These simulations indicate that the ancient dynamo must have been >10-100 times stronger than at present and rules out several hypothesized mechanisms for generating the early field, leaving Earth-like core convection as the most likely process.

Planetary Lunch Seminar —

Colloquia topics span the range of research interests of the department’s planetary sciences research program, and the talks are intended to appeal to any graduate students, postdocs, research scientists, and faculty with a background in planetary science. Speakers include members of the MIT community and visitors.

Contact: planetary-org@mit.edu