The surface composition of Charon - Tentative identification of water ice

by: Marcialis, R. L.; Lebofsky, L. A.; Rieke, G. H.

ABSTRACT

The Mar. 3, 1987, Charon occultation by Pluto was observed in the infrared
at 1.5, 1.7, 2.0, and 2.35 micrometers. Subtraction of fluxes measured
between second and third contacts from measurements made before and after
the event has yielded individual spectral signatures for each body at
these wavelengths. Charon's surface appears depleted in methane relative
to Pluto. Constancy of flux at 2.0 micrometers throughout the event shows
that Charon is effectively black at this wavelength, which is centered on
a very strong water absorption band. Thus, the measurements suggest the
existence of water ice on Pluto's moon.

Science, ISSN 0036-8075, vol. 237, Sept. 11, 1987, p. 1349-1351.