Charon: A Brief History of Tides

In 2015, the New Horizons spacecraft flew past Pluto and its moon Charon, providing the first
clear look at Charon's surface. New Horizons images revealed an ancient surface, a large, intricate canyon
system, and many fractures, among other geologic features. Here, we assess whether tidal stresses played a
significant role in the formation of Charon's tensile fractures. Although presently in a circular orbit, most
scenarios for Charon's orbital evolution include an eccentric orbit for some period of time and possibly an
internal ocean. Past work has shown that these conditions could have generated stresses comparable in
magnitude to other tidally fractured moons, such as Europa and Enceladus. However, we find no correlation
between observed fracture orientations and those predicted to form due to eccentricity driven tidal stress.
It, thus, seems more likely that Charon's orbit circularized before its ocean froze and that either tidal stresses
alone were insufficient to fracture the surface or subsequent resurfacing removed these ancient fractures.