The moon of another planet will be the first place where Jupiter mission will go

The Jupiter Icy Moons Explorer (JUICE) mission is set to launch on an Ariane 5 rocket on Kourou, France

One of the most conclusive tests of the ocean theory will come from topographical maps made by JUICE’s laser altimeter. Because Ganymede moves slightly closer to and farther from Jupiter during its weekly orbit, and because it experiences the gravitational pull of the other moons, it stretches and compresses under tidal forces. The surface may swing up and down by as much as 10 metres if there is a huge amount of ice on the water. “If it’s only a solid tide, it would be less than a metre,” he adds.

Jupiter is only going to fly by the second largest moon, Callisto, once, compared to 21, which it is going to do twice. That’s because Europa will be studied closely by a NASA mission called Europa Clipper, which is due to launch in late 2024.

“Our radiometer saw through the ice on Europa and Ganymede for the first time, and their radar instrument is designed to do that in a different way,” says Scott Bolton, Juno’s principal investigator and an astronomer at the Southwest Research Institute. “Their data set will inform us so that we can look back and reinterpret Juno data,”

When the Galileo probe was done it dove into Jupiter’s depths and burned up in its atmosphere. Cassini later did the same, plunging into Saturn in 2017, collecting a last bit of data—and preventing space trash—while completing its mission in dramatic fashion. A similar fate awaits Juice, which will plummet into Ganymede at the end of its lifespan, probably in 2035 or a few years later.

The Jupiter Icy Moons Explorer (JUICE) craft is currently positioned atop an Ariane 5 rocket at the European spaceport in Kourou, French Guiana, and is set to launch at 9:15 local time on 13 April. Véronique Loisel, the programme director and launch operator of Arianespace, said at a press conference in Kourou last week that there was no launch window and only one launch instant.

Such a precise lift-off time is required to insert the spacecraft into the correct orbit around the Sun, explained Loisel, who is based in Évry, France. The next opportunity will come soon after if the launch is delayed because of bad weather.

An Engineering Briefing on the Double Fly by for the European Space Agency (ESA) Mission to the Outskirts of the Solar System

If everything goes according to plan, the European Space Agency (ESA) probe will circle back and pass close to both Earth and the Moon in around one year’s time, which will help to slingshot the spacecraft towards the outer Solar System. The double fly by will need the most accurate gravity assist manoeuvre ever done, said an engineer at the briefing. Atzei is based at the agency’s European Space Research and Technology Centre in Noordwijk, the Netherlands.