In early June, NASA released new images from the Juno spacecraft, showing the first close-up of Ganymede, Jupiter's largest moon, since the Galileo spacecraft visited two decades ago. 

The Juno mission to Jupiter has been circling our solar system’s largest planet since 2016, taking images of the planet's magnificent swirls. It’s already observed so much about Jupiter: lightning in the clouds, movement deep in the atmosphere, and giant aurorae similar to the famous Aurora Borealis here on Earth. Next, it’s setting its sights on Ganymede.

Although Mars may seem like the most popular target to search for life, outer solar system moons like Ganymede have quite a bit of potential, too. These icy moons (including Ganymede, Europa, and Enceladus) likely have oceans of water underneath an icy outer shell. Ganymede in particular has a thick ice shell with chunks of rock embedded in it and bright streaks across the surface, making it an interesting and active place for astronomers to study. Ganymede is also the only moon that we know has a magnetic field — an important protective shield for life.

These new images of Ganymede show the most detailed view of the moon's surface yet. Scientists hope that information from Juno will tell us more about how thick the ice shell is, what it’s made of, and how much radiation is hitting the surface—all important things for understanding the moon’s habitability, and for planning future missions.