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M.H. Moore (NASA/Goddard Space Flight Center), R.L. Hudson (Eckerd College), R.W. Carlson (Jet Propulsion Laboratory)
Spectra of the icy moons of Jupiter reveal surfaces dominated by water-ice along with hydrated materials and minor amounts of SO2, and CO2 (1). The surfaces of Europa, Ganymede, and Callisto undergo significant bombardment by the Jovian magnetospheric radiation (protons, electrons, sulfur and oxygen ions), which can alter surface compositions through radiolysis and ion implantation. Results from our laboratory studies of the IR spectra of proton-irradiated ices relevant to these moons provide new information about possible chemical pathways. Our data also predict possible species for future IR detections, and serve as inputs for understanding the physical habitability of ice surface layers that is of interest for future missions. We will review the formation and identification of several radiation products from H2O + SO2, H2O + H2S, and H2O + SO2 + CO2 ices. The formation and stability of hydrated sulfuric acid in a radiation environment is examined. In addition, a more complicated four component mixture, H2O + SO2 + CO2 + CH4, has been examined to determine the evolution of methane's 3.3 micron feature during radiolysis. The IR detection of CH4 is of interest to astrobiologists as a possible marker of methanogens in an irradiated ice environment. This research is supported through NASA's Planetary Atmospheres and Planetary Geology and Geophysics programs.
(1) see review by Roush, T.L., JGR 2001, 106, 33,315.
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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.