Jupiter is the largest planet in our solar system and also the one with the greatest number of moons. Estimates of their number range between 82 and 95. Most of them have been discovered within the past two decades.
Jupiter’s turbulent atmospheric. NASA/JPL-Caltech/SwRI/MSSS, Kevin M. Gill, CC BY
JUICE was the first mission funded by more than one billion euros as part of ESA’s CosmicVision program. It aims to answer four key questions:
How do life and planets form?
What is the Solar System?
What are the basic laws of physics that govern the universe?
What is the current universe made of, and how did it come to be?
JUICE was selected ahead of other missions proposed because it addressed the first and final questions.
By observing or deducing, NASA’s Hubble Space Telescope, Voyager, and Galileo space probes, Juno, have already gathered some clues.
Ocean moons contain more water than Earth.
NASA’s Galileo discovered water in the moons for the first time in 1995. The data captured by the probe revealed that there are huge liquid oceans under the crusts of Callisto’s three icy satellites, Europa, Ganymede, and Io.
Hubble’s Space Telescope found geysers on Europa in 2014. The bases of the geysers appeared caked in salts, including carbonates. Europa is likely to meet the criteria of habitability.
The four elements of Carbon, Hydrogen, Oxygen, and Nitrogen (CHON) are the symbols for the major chemical elements that make up living organisms.
Water is liquid and acts as a solvent.
The energy that enables the development of living things.
A stable environment (orbits, rotation, average temperatures…)
The Galilean Moons also enjoy the gravitational power of Jupiter. This creates a significant tidal effect and allows the two last conditions to be met.
Why Ganymede should be the main goal
JUICE will study Ganymede in greater depth than Callisto or Europa. It is not just because it’s the largest satellite in the Solar System. It also has a magnetic field. Ganymede, like Earth’s magnetosphere, can protect life from cosmic rays by diverting them away from Jupiter’s Radiation Belts.
The magnetic field of Jupiter appears to bathe Ganymede’s northern light belts. The auroras move when Jupiter’s magnetic fields change. This indicates that there is a large amount of saltwater under Ganymede’s crust, which would affect its magnetic field. NASA/ESA
JUICE: A probe of extremes
JUICE will not follow a straight path to reach the Jovian System. The spacecraft will instead fly by four planets and their moons, which will change and speed up its trajectory. This trick is also known as the gravity assistance maneuver.
JUICE must contend with the highest levels of radiation in the Solar System. It means that the electronic modules will have to be protected by lead and components “hardened” in order to withstand the harsh environment.
JUICE must also cope with extreme temperature variations, from +250degC when it passes Venus to -230degC within the Jovian system. The spacecraft is coated with a Multilayer Thermal Insulation made of grey silicon aluminum alloy to maintain a constant internal temperature. This has earned the probe the nickname “silver beaut.””
Energy Problem
The satellite is 25 times less likely to receive solar energy around Jupiter because it’s five times farther from the Sun. The spacecraft is missing a Radioactive Battery as Europe has not been able to industrially produce them, unlike the United States, Russia, and China.
The craft’s solar panels, which have a surface area of 85m2, will be used to power the instruments and equipment with 1000W. These panels are tested for temperature and radiation variations.
