Stunning photo of Jupiter’s largest moon marks 10 years for Juno probe

Thursday, Aug. 5 marked 10 years since NASA sent Juno off on a one-way trip to explore the largest planet in our solar system.

The probe didn’t reach its destination, Jupiter, until July 2016. But NASA nonetheless shared a little treat with all of us space-gazers here on Earth to celebrate the Jupiter orbiter’s 10 years of service. That treat, a photo of the Jupiter moon Ganymede snapped on July 20, comes compliments of Juno’s JIRAM, or Jovian Infrared Auroral Mapper.

Jupiter’s moon, Ganymede, captured by the Juno probe just a few weeks ahead of the 10th anniversary of its launch.
Credit: NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM

Ganymede isn’t just a cosmic celeb for being Jupiter’s largest moon. It’s also the largest moon in our entire solar system, measuring roughly one-and-a-half time’s larger than Earth’s moon. A bit less than half of its water-ice crusted surface is dark and pitted by impact craters, NASA says. The rest is lighter in color and marked by grooved terrain.

You can’t make out much in the way of fine details in this new image, but that’s because of the source. Juno’s JIRAM is an infrared camera, and the image above is a composite culled from three separate flybys of the moon, the last of which happened on July 20. The composite isn’t meant to pick up fine surface details; rather, it offers a view of Ganymede’s “icy shell and the composition of the ocean of liquid water beneath.”

The moon’s unique surface features are much easier to spot in more traditional photos. This one, captured on June 7, gives us Juno’s view of Ganymede during the closest flyby of the moon by any spacecraft in the past 20 years. You can clearly see the intricate grooved terrain here, which may or may not be the result of tectonic fault lines.

Ganymede’s surface in more detail, also compliments of Juno.
Credit: NASA/JPL-Caltech/SwRI/MSSS

Obviously, the 10-year-old Juno wasn’t around during the previous closest flyby. The Jupiter orbiter is the second spacecraft to visit the moon and the gas giant it orbits, after the Galileo probe.

The next big moment for Juno is coming in Sept. 2022 when the probe settles in for a close-up look at Jupiter’s moon, Europa, with a flyby of the moon Io to follow a year later. All of this, including these new 10th anniversary images, amount to bonus time for the solar-powered probe. NASA formally extended Juno’s mission through 2025 “or its end of life” back in Jan. 2021.

Probes like this aren’t meant to be retrieved. Juno’s work will end with its destruction, when Jupiter’s enormous gravitational pull brings the spacecraft in close enough to tear it apart.