Moons and Icy Worlds: June 2021

Ground-based spectroscopy of Ganymede's surface has revealed the surprising presence of dense-phase molecular oxygen (O2) via weak absorptions at visible wavelengths. To date, the state and stability of this O2 at the temperatures and pressures of Ganymede's surface are not understood.

Magnetic investigations of icy moons have provided some of the most compelling evidence available confirming the presence of subsurface, liquid water oceans.

Ganymede's atmosphere is produced by charged particle sputtering and sublimation of its icy surface.