  Published near-infrared spectra of the four largest classical Uranian
satellites display the presence of discrete deposits of CO$_2$ ice, along with
subtle absorption features around 2.2 $\mu$m. The two innermost satellites,
Miranda and Ariel, also possess surfaces heavily modified by past endogenic
activity. Previous observations of the smallest satellite, Miranda, have not
detected the presence of CO$_2$ ice, and a report of an absorption feature at
2.2 $\mu$m has not been confirmed. An absorption feature at 2.2 $\mu$m could
result from exposed or emplaced NH$_3$- or NH$_4$-bearing species, which have a
limited lifetime on Miranda's surface, and therefore may imply that Miranda's
internal activity was relatively recent. In this work, we analyzed
near-infrared spectra of Miranda to determine whether CO$_2$ ice and the
2.2-$\mu$m feature are present. We measured the band area and depth of the
CO$_2$ ice triplet (1.966, 2.012, and 2.070 $\mu$m), a weak 2.13-$\mu$m band
attributed to CO$_2$ ice mixed with H$_2$O ice, and the 2.2-$\mu$m band. We
confirmed a prior detection of a 2.2-$\mu$m band on Miranda, but we found no
evidence for CO$_2$ ice, either as discrete deposits or mixed with H$_2$O ice.
We compared a high signal-to-noise spectrum of Miranda to synthetic and
laboratory spectra of various candidate compounds to shed light on what species
may be responsible for the 2.2-$\mu$m band. We conclude that the 2.2-$\mu$m
absorption is best matched by a combination of NH$_3$ ice with NH$_3$-hydrates
or NH$_3$-H$_2$O mixtures. NH$_4$-bearing salts like NH$_4$Cl are also
promising candidates that warrant further investigation.
