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M. H. Moore (NASA Goddard Space Flight Center), R. L. Hudson (Eckerd College and NASA GSFC), R. W. Carlson (Jet Propulsion Lab)
Spectra of Europa reveal a surface dominated by water-ice (1) along with hydrated materials (2,3) and minor amounts of SO2 (4,5), CO2(6), and H2O2 (7). The surface is under intense bombardment by the Jovian magnetospheric radiation (protons, electrons, sulfur and oxygen ions), which can alter the surface composition through radiolysis and ion implantation. In order understand the radiation induced changes in Europa-like ices, we have measured the mid-IR spectrum of proton irradiated H2O ice containing SO2 or H2S. Ices with H2O/SO2 or H2O/H2S ratios of 3 and 30 have been irradiated at 86 K, 110 K and 132 K. Several new products are identified, e.g. sulfate is formed in H2O + SO2 irradiated ices. The radiation half-life of SO2 and H2S in H2O is calculated. Applications of these results to Europa are included.
This research is supported through NASA/ Planetary Geology and Geophysics
(1) Calvin, W.M. et al. 1995, J. G R 100; (2) McCord, T.B. et al. 1998, Science 280; (3) Carlson, R.W. et al, 1999, Science 97; (4) Lane, A.L. et al. 1981, Nature 292; (5) Noll, K.S. et al. 1995 JGR 102; (6) Smythe, W.D. et al. 1998 LPSC; (7) Carlson, R.W. et al. 1999, Science 283
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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.