Winter 2021

Fridays at 12:00 PM

Zoom information can be found on the EPS advising Google calendar

January 22, 2021

Speaker: Alexis Cartwright-Taylor, University of Edinburgh, School of GeoSciences

Title: Damage localization and catastrophic failure of brittle rocks – what can we learn from combining in-situ x-ray microtomography with acoustic emissions?


January 29, 2021

Speaker: Ronald Ballouz, Lunar and Planetary Laboratory, University of Arizona

Title: The strength of solid asteroids constrained by craters on asteroidal boulders and Near-Earth Object population estimates


February 5, 2021

Speaker: Nathaniel Miller, USGS

Title: Fault roughness and earthquake rupture at plate boundary scales


February 12, 2021

Speaker: Xian Shi, Max Planck Institute for Solar System Research

Title: Near-nucleus activities of comet 67P/Churyumov-Gerasimenko observed by Rosetta/OSIRIS

Abstract: Between August 2014 and September 2016, ESA's Rosetta spacecraft rendezvoused with its target comet 67P/Churyumov-Gerasimenko and accompanied it through its perihelion passage. During the over-two-year operation, the scientific camera system on board Rosetta, OSIRIS, acquired more than 70,000 images of the comet with unprecedented resolution and coverage. In this talk, I will introduce our work on investigating gas and dust activities in the ambient coma of 67P's nucleus. Our analyses of the imaging data, combined with thermophysical and gas/dust dynamic models, show how water-ice sublimation could drive both nominal and uncommon cometary activities.


February 19, 2021

Speaker: Brad Lipovsky, Harvard University

Title: Cracking the case of ice shelf fracture

February 26, 2021

Speaker: Claire Nichols, University of Oxford

Title: The Geometry of the Ancient Lunar Magnetic Field

Abstract: Paleomagnetic studies of Apollo samples indicate that the Moon generated a core dynamo lasting for at least 2 billion years. However, the geometry of the lunar magnetic field is still largely unknown because the original orientation of nearly all Apollo samples are unconstrained. Determining the direction of the lunar magnetic field over time could elucidate the mechanism by which the lunar dynamo was powered, whether the magnetic field underwent reversals, and whether the Moon experienced true polar wander. I will present measurements of the lunar magnetic field at 3.7 Ga as recorded by Apollo 17 mare basalts 75035 and 75055. These samples formed as part of basalt flows that make up wall-rock within Camelot crater in the Taurus-Littrow valley. Using layering in the parent boulder for 75055, we inferred its original paleohorizontal orientation on the lunar surface at the time of magnetization. We find that 75035 and 75055 record mean paleointensities of 37.3 ± 5.4 µT and 43.6 ± 4.6 µT, respectively. Furthermore, 75055 records a paleoinclination of 34 ± 11°. This inclination is consistent with, but does not require, a selenocentric axial dipole. Additionally, although true polar wander is also not required by our data, polar wander inferred from independent studies is consistent with our reported paleoinclination.


March 5, 2021

Speaker: Manoochehr Shirzaei, Virginia Tech


March 12, 2021

Speaker: Shannon Mackenzie, Johns Hopkins University