# # Program information file # PROGRAM_ID 2021B002 PROGRAM_TITLE The Neptunian satellite Nereid: A key compositional link between ice giant satellites and trans-Neptunian Objects PROGRAM_INV1 Richard Cartwright PROGRAM_INV2 Bryan Holler PROGRAM_INV3 Silvia Protopapa PROGRAM_INV4 Michael Lucas PROGRAM_INV5 Tom Nordheim PROGRAM_SCICAT solar system PROGRAM_ABSTRACT_BEG We propose to use SpeX to characterize the surface composition of the Neptunian moon Nereid, which could represent a key compositional link between ice giant satellites and trans-Neptunian Objects [TNO]. The available spectra of Nereid suggest that it has a low albedo surface with weak H2O bands and spectral hints of a 2.2-micron band, similar to the classical Uranian moons and H2O-bearing TNOs like Charon and Orcus. However, the low signal-to-noise [S/N] of these data limits our ability to constrain the composition of Nereid and interpret the possible compositional links between this Neptunian moon and different populations of icy bodies in the outer Solar System. Therefore, we aim to collect higher S/N, near-infrared spectra of Nereid to investigate its surface composition. The PRISM mode of SpeX [R ~94, 0.8'' slit] is ideal for the characterization of the 1.65-micron H2O ice band and the 2.2-micron band. The 1.65-micron H2O and 2.2-micron bands are relatively wide, spanning ~0.07 microns and ~0.06 microns, respectively, requiring R of > 74 to detect. According to the SpeX Observation Calculator, 3 hours of integration time on Nereid should provide S/N > 25 at 1.65 and 2.2 microns. Thus, our proposed SpeX observations will provide much higher quality spectra than previous near-infrared spectral observations of Nereid [factor of ~2.5 higher S/N]. We will guide using MORIS [0.7'' dichroic] thereby mitigating slit losses. PROGRAM_ABSTRACT_END