[Previous] | [Session 47] | [Next]
R.A. Baragiola, D.A. Bahr, M. Fama, B.D. Teolis (University of Virginia)
We performed quantitative laboratory radiolysis experiments on water ice between 20 and 120 K, with Lyman-\alpha photons and 80-200 keV protons. We measured sputtering of atoms and molecules, and the trapping of radiolytic molecular species. The experiments were done at fluences corresponding to exposure of the surface of the Jovian icy satellites to their radiation environment up to thousands of years. For both photon and ion irradiation, O2 molecules are ejected from the ice at a rate that grows roughly exponentially with temperature up to 135 K, and then declines. The amount of radiolytic O2 trapped in the ice is obtained by thermal desorption mass spectrometry, and is found to be orders of magnitude smaller than the values assumed in a proposal for an energy source that may fuel bacterial life in Europa.