Jupiter Icy Moons Explorer

Juice, short for Jupiter Icy Moons Explorer, is a mission led by the European Space Agency (ESA). It is designed to investigate Jupiter, its space environment and three large icy moons: Ganymede, Europa and Callisto. The mission will study these moons as planetary bodies and as possible habitats, while also examining how Jupiter's system works. ESA launched Juice on 14 April 2023 from Europe's Spaceport in French Guiana aboard an Ariane 5 rocket. Its planned arrival at Jupiter is July 2031.

Juice will make repeated flybys of the icy moons during its tour of Jupiter. Ganymede is the mission's primary scientific target; the spacecraft is planned to enter orbit around it in late 2034. The study of Ganymede will include its subsurface ocean, icy crust, internal structure, geology and magnetic field. Juice will also examine Europa and Callisto, comparing their surface and subsurface environments and assessing properties relevant to habitability. These are investigations of environments and chemical conditions, not a direct search for organisms.

The spacecraft carries a suite of remote-sensing, geophysical and in-situ instruments. These include cameras and spectrometers to study surfaces and atmospheres, an ice-penetrating radar to probe beneath icy crusts, and instruments that measure magnetic fields, plasma and particles. Radio-science measurements and other geophysical techniques will help researchers investigate the moons' interiors and gravitational properties. NASA's Jet Propulsion Laboratory contributes the radar transmitter and receiver hardware and leads U.S. contributions to selected instruments, as part of a broader international scientific collaboration.

The icy moons may contain liquid-water oceans beneath their outer ice, making them important locations for studying how potentially habitable environments form and persist. Comparing Ganymede, Europa and Callisto can help scientists understand how different worlds in one planetary system evolved. Juice's work at Ganymede is especially distinctive: ESA describes it as the first spacecraft planned to orbit a moon in the outer Solar System. The mission's findings will characterize planetary environments and their potential habitability, rather than demonstrate that life exists.