  The 27 satellites of Uranus are enigmatic, with dark surfaces coated by
material that could be rich in organics. Voyager 2 imaged the southern
hemispheres of Uranus' five largest 'classical' moons Miranda, Ariel, Umbriel,
Titania, and Oberon, as well as the largest ring moon Puck, but their northern
hemispheres were largely unobservable at the time of the flyby and were not
imaged. Additionally, no spatially resolved datasets exist for the other 21
known moons, and their surface properties are essentially unknown. Because
Voyager 2 was not equipped with a near-infrared mapping spectrometer, our
knowledge of the Uranian moons' surface compositions, and the processes that
modify them, is limited to disk-integrated datasets collected by ground- and
space-based telescopes. Nevertheless, images collected by the Imaging Science
System on Voyager 2 and reflectance spectra collected by telescope facilities
indicate that the five classical moons are candidate ocean worlds that might
currently have, or had, liquid subsurface layers beneath their icy surfaces. To
determine whether these moons are ocean worlds, and investigate Uranus' ring
moons and irregular satellites, close-up observations and measurements made by
instruments onboard a Uranus orbiter are needed.
