Jupiter Icy Moons Explorer: what Juice is to study at Ganymede, Callisto and Europa
Background
Juice is the Jupiter Icy Moons Explorer, a spacecraft of ESA. It is to look closely at Jupiter and at three of the planet's big moons that are thought to hold oceans under their ice - Ganymede, Callisto and Europa. The craft lifted off on 14 April 2023 on an Ariane 5 from Europe's Spaceport in French Guiana. Sunlight is weak that far out, so it carries solar wings of 85 square metres. Instead of flying straight there it is using gravity assists: a Moon-Earth pass, a swing by Venus, an Earth pass in September 2026, and a fourth, a further Earth pass, due in January 2029. ESA says the craft reaches Jupiter in July 2031 and will then make repeated close passes of the Jovian moons. The aim is to treat those moons as worlds in their own right and ask whether they could be habitats.
In plain words
Juice Jupiter Icy Moons Explorer — The ESA spacecraft sent to study Jupiter and its icy moons.
Gravity assist Gravity assist — A close pass by a planet or moon that changes a spacecraft's speed and direction without using fuel.
ESA European Space Agency — The space agency run jointly by European countries.