These values are unusually high for a closer moon and can be explained by the past influence of the closest Galilean satellite Io ; in the past , several mean motion resonances with Io would have passed through Thebe 's orbit as Io gradually moved away from Jupiter , and these excited Thebe 's orbit . These values are unusually high for an inner satellite and can be explained by the past influence of the innermost Galilean satellite , Io ; in the past , several mean motion resonances with Io would have passed through Thebe 's orbit as Io gradually receded from Jupiter , and these excited Thebe 's orbit .