Abstract
The latest decadal survey identified the Uranus system as the
highest-priority new target for a NASA Flagship mission. Ariel and
Miranda are potential ocean worlds with evidence of resurfacing
potentially due to past elevated heat flow. Learning about the geologic
histories of these icy moons is important for understanding the
potential for life in the outer solar system. Using limited data
acquired by the Voyager 2 spacecraft, we explore open questions about
the surfaces of Uranian satellites to gain a better understanding of
their evolutionary histories. In this work, we update the estimates of
Ariel and Miranda’s simple-to-complex transition diameters, which have
not yet been measured using modern GIS techniques and reprocessed data.
The simple-to-complex transition diameter is a value used on many worlds
to infer the composition of the surface. For the Uranian satellites,
this value was last estimated shortly after the Voyager 2 flyby with a
dataset of 18 craters. We use reprocessed topography from more than 100
craters to estimate a simple-to-complex transition diameter on Ariel of
~26 km, consistent with an icy surface composition. We
place a lower limit of ~49 km on the transition diameter
for Miranda, where we cannot identify any complex craters. We also
estimate the relative and absolute ages of terrains on Ariel and
Miranda. Our results agree with recent studies showing that they likely
experienced relatively recent resurfacing. Finally, we suggest imaging
requirements for the future mission to Uranus to answer outstanding
questions about Ariel and Miranda.