Jupiter's magnetosphere knocking molecules from ice on surface of Callisto does not explain amount of atmospheric oxygen

A team of scientists affiliated with several institutions in the U.S. has tested a theory created to explain the amount of oxygen in the atmosphere of Callisto, one of Jupiter's moons, and has found that it falls short. In their paper published in Journal of Geophysical Research: Planets, the group describes how they tested the theory and other possible avenues of research.