How will Juice do this?

Juice is a unique mission. It will be the first spacecraft to orbit a moon other than our own, and also the first to change orbit from another planet to one of its moons (Jupiter to Ganymede). It will first orbit Jupiter, performing numerous flybys of the planet’s moons – including 12 of Ganymede – as it loops around the gas giant. Juice will then hop across to Ganymede and begin its in-depth study of the moon. (More on Juice’s journey to Jupiter.)

Juice will measure how Ganymede rotates, its gravity and geophysics, its shape and interior structure, its magnetic field and atmosphere, its composition and mineralogy, its icy crust and surface features, its emissions to space and interactions with its surroundings, and, crucially, its subsurface ocean. It will complete a ‘tomography’ of Ganymede for the first time, observing it from multiple perspectives to reconstruct a view of its interior, and assess the moon’s biosignatures (elements thought to be biologically essential, although not sufficient, for life: examples include carbon, oxygen, magnesium, iron and liquid water).