The Jupiter Icy Moons Explorer Just Launched, Here’s What it Will Study

The European Space Agency’s (ESA) JUpiter ICy moons Explorer (JUICE) successfully launched on April 14th of this year. This interplanetary spacecraft will take 8 years to reach Jupiter, where it will then study the planet and three of Jupiter’s largest moons, Ganymede, Callisto, and Europa.

Image of Jupiter and one of its moons, Io taken by Cassini after its closest approach to the planet. Credit: NASA/JPL/University of Arizona.

Jupiter’s moon Europa in particular has long been a planned target of study for a long time because of its potentially massive liquid water ocean underneath the frozen surface. Surface based telescopes gave us a glimpse at its icy surface, and flybys of Voyager 1 and 2 showed early evidence of liquid water. In 2019, researchers detected water vapor above Europa’s surface for the first time using a spectrograph at the Keck Observatory in Hawaii.

In addition to briefly studying Europa, Jupiter and two of its other moons will also be explored by JUICE during planned flybys. This is because of evidence of water on these moons discovered by NASAs Galileo spacecraft. More recently, in 2021 the Hubble Space Telescope found evidence of an ocean estimated to be 60 miles deep under the icy surface of Ganymede, making this moon a top priority for JUICE.