  The large and tidally-locked classical moons of Uranus display longitudinal
and planetocentric trends in their surface compositions. Spectrally red
material has been detected primarily on the leading hemispheres of the outer
moons, Titania and Oberon. Furthermore, detected H2O ice bands are stronger on
the leading hemispheres of the classical satellites, and the leading/trailing
asymmetry in H2O ice band strengths decreases with distance from Uranus. We
hypothesize that the observed distribution of red material and trends in H2O
ice band strengths results from infalling dust from Uranian irregular
satellites. These dust particles migrate inward on slowly decaying orbits,
eventually reaching the classical satellite zone, where they collide primarily
with the outer moons. The latitudinal distribution of dust swept up by these
moons should be fairly even across their southern and northern hemispheres.
However, red material has only been detected over the southern hemispheres of
these moons (subsolar latitude 81 S). Consequently, to test whether irregular
satellite dust impacts drive the observed enhancement in reddening, we have
gathered new ground-based data of the now observable northern hemispheres of
these moons (sub-observer latitudes, 17 to 35 N). Our results and analyses
indicate that longitudinal and planetocentric trends in reddening and H2O ice
band strengths are broadly consistent across both southern and northern
latitudes of these moons, thereby supporting our hypothesis. Utilizing a suite
of numerical best fit models, we investigate the composition of the reddening
agent detected on these moons, finding that both complex organics and amorphous
pyroxene match the spectral slopes of our data. We also present spectra that
span 2.9 to 4.1 microns, a previously unexplored wavelength range in terms of
spectroscopy for the Uranian moons.
