  In 2015, the New Horizons spacecraft flew past Pluto and its moon Charon,
providing the first clear look at the surface of Charon. 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 tensile fractures on
Charon. Although presently in a circular orbit, most scenarios for the orbital
evolution of Charon 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 the orbit of
Charon circularized before its ocean froze, and that either tidal stresses
alone were insufficient to fracture the surface or subsequent resurfacing
remove these ancient fractures.
