From modelled crater chronology of the outer solar system to the absolute ages of Enceladus' terrain
Emily Wong
Earth Life Science Institute, Tokyo Institute of Technology
Two issues prevent us from obtaining absolute surface ages of the icy satellites of the giant planets. First, we do not have in situ samples to measure their radiometric ages. Second, the cratering chronology in the outer Solar System could be dissimilar to that of the Moon and Mars; thus, the conventional ages estimation by extrapolating from the lunar chronology is inaccurate. These restrictions leave us to use modelling to recreate the outer Solar System's evolution and estimate the surface ages of the icy satellites.
We performed a series of N-body dynamical and Monte Carlo simulations based on the Nice model evolution of the giant planets during the episode of their migration starting 4.5 billion years ago. We build an outer Solar System crater chronological model to derive the rate of impacts, and expected number of craters.
Here we focus on several terrains on the Saturnian satellites, which have been surveyed extensively, and estimate their surface ages more accurately with our new modelled crater chronologies that have a higher impact resolution. We give model ages for the surface of Enceladus, a small Saturnian satellite that shows a high amount of activity, and its implications for its formation and tidal dissipation in Saturn.
Here you can play back the presentation (sound from 05:03)
