Water Ice on Triton

We report the spectroscopic detection of H2O ice on Triton, evidenced by the broad absorptions in the near infrared at 1.55 and 2.04 micron. The detection on Triton confirms earlier preliminary studies (D. P. Cruikshank, R. H. Brown, and R. N. Clark, Icarus 58, 293-305, 1984). The spectra support the contention that H2O ice on Triton is in a crystalline (cubic or hexagonal) phase. Our spectra (1.87-2.5 micron) taken over an interval of nearly 3.5 years do not show any significant changes that might relate to reports of changes in Triton's spectral reflectance (B. Buratti, M. D. Hicks, and R. L. Newburn, Jr., Nature 397, 219, 1999), or in Triton's volatile inventory (J. L. Elliot et al., Nature 393, 765-767, 1998)