Ganymede doubtless has some particular traits. It isn’t simply Jupiter’s largest moon, however the largest in your entire photo voltaic system by far—concerning the dimension of Mercury and our moon mixed. It harbors about six instances as a lot liquid water as Earth, but it surely may very well be hidden beneath 100 miles of ice, Witasse says. Ganymede’s additionally distinctive in possessing an iron core that generates the moon’s personal magnetic discipline—the one rocky physique within the photo voltaic system to take action, aside from Mercury and Earth. Its magnetic discipline might have originated from its proximity to Jupiter, which might have induced a tidal flexing of its inside construction.
Juice comes geared up with quite a few instruments for scientists to look at these heavenly our bodies from afar, together with a high-resolution optical digital camera known as Janus, a laser altimeter known as GALA to measure Ganymede’s tidal deformation by Jupiter’s gravitational pull, a submillimeter-wave instrument known as SWI that may look at Jupiter’s ambiance, and a magnetometer known as J-Magazine to check the interplay of Jupiter’s and Ganymede’s magnetic fields. “The spacecraft’s full suite of cutting-edge devices makes Juice the following step in science,” says Alessandro Atzei, the undertaking’s payload system engineer. “We count on quite a lot of new findings, together with the composition of the magnetic discipline, the fabric of the moons, and an understanding of the ambiance of Jupiter.”
Atzei additionally highlights the spacecraft’s ice-penetrating radar and its gravity probe, named RIME and 3GM, respectively. The radar will have the ability to spot pockets of underground water right down to a depth of about 10 kilometers, and it’s in all probability delicate sufficient to detect it beneath Europa’s floor, however not Ganymede’s. The gravity probe might present details about Ganymede’s inside ocean, and it might conclusively decide whether or not Callisto has an ocean deeper beneath floor.
Juice follows an extended line of area probes to the outer planets. NASA’s Pioneer 10 flew by Jupiter in 1973, and both Voyager spacecraft adopted six years later. The Galileo spacecraft orbited Jupiter for years beginning in 1995, enabling the invention of the moon’s magnetic discipline. As we speak, NASA’s Juno orbiter remains to be operating its prolonged mission—on April 8 it accomplished its fiftieth shut cross of Jupiter since 2016. It’s onerous to foretell if Juno will nonetheless be chugging alongside when Juice arrives, however the brand new craft might be constructing on its predecessor’s accomplishments and legacy.
“Our radiometer noticed by the ice on Europa and Ganymede for the primary time, and their radar instrument is designed to do this otherwise,” says Scott Bolton, Juno’s principal investigator and an astronomer on the Southwest Analysis Institute. “Their information set will inform us in order that we will look again and reinterpret Juno information,”
Juno has revealed dramatic views of Jupiter’s mysterious auroras and swirling polar cyclones, and it mapped an odd patch of the planet’s magnetic field nicknamed the Nice Blue Spot. (It’s completely different from the enduring red, Earth-sized storm.) Juno’s solar-powered system and its armored vault, which shields delicate electronics from Jovian radiation, proved to be such an efficient design that Juice engineers adopted one thing related. There will even be some synergy between Juice and NASA’s upcoming Europa Clipper, an orbiter deliberate to launch subsequent yr and arrive in 2030.
When the Galileo probe completed its work, it dove into Jupiter’s depths and burned up within the gasoline big’s ambiance. Cassini later did the same, plunging into Saturn in 2017, gathering a final bit of knowledge—and stopping space trash—whereas finishing its mission in dramatic trend. An analogous destiny awaits Juice, which can plummet into Ganymede on the finish of its lifespan, in all probability in 2035 or just a few years later.
The gasoline big and its main moons have been objects of human fascination since Galileo Galilei found Ganymede and its sister moons in 1610 and made telescopic observations of Jupiter itself. To at the present time, folks scan the night time sky for the planet and for Venus. Now area businesses are giving the Jovian system its closest look but. “I feel Jupiter is changing into a marketing campaign goal, like Mars has been for fairly some time,” Bolton says. “It is a planet that has intrigued us for a very long time, but it surely’s not simple to get to. It will be nice to have a number of spacecraft there on the identical time.”