Alyssa Rhoden Cracks the Ice of Europa

Europa's surface records a complex history of geologic activity including fracture systems driven by tidal stress, which varies daily as Europa executes its eccentric orbit around Jupiter. Obliquity, physical libration, and non-synchronous rotation would also contribute to the pattern of tidal stress on Europa. Hence, we can use observed fracture systems to constrain these rotational parameters. Using cycloids and strike-slip faults, Dr. Rhoden has been able to probe Europa's rotation state and uncover the first geologic evidence of non-negligible obliquity. Dr. Rhoden will present this case for obliquity and physical libration and implications for non-synchronous rotation and polar wander. In addition, she will present a model she has developed for a fault's response to tidal stress that accurately predicts the slip direction of 75% of strike-slip faults identified in an extensive survey of Europa imagery.