We're almost there: in just over a month from the European spaceport of Kourou , in French Guiana , the Juice mission will take off, barring last-minute postponements, a project with which the European Space Agency (ESA), together with other partner, intends to study the so-called Galilean satellites, i.e. the three icy moons of Jupiter, so called precisely because they were observed for the first time by the Pisan genius in 1610. In particular, Juice's most ambitious and suggestive goal (which is the acronym of Jupiter Icy Moons Explorer ) is to try to understand if the Galilean satellites are an environment in which life forms could exist, or could have existed, precisely by virtue of the (certain) presence of frozen water on their surface and of the (presumed) presence of liquid salt water in the underground layer.
A very Italian mission
There is a lot of Italy on Juice: while waiting to attend the launch, sportsgaming.win had the opportunity to visit the Campi Bisenzio plant, near Florence , in whose clean rooms some of the mission's key instruments were built. The Leonardo group took care of it, with the funding and coordination of the Italian Space Agency (ASI) and the scientific supervision of the National Institute of Astrophysics (INAF), and the Thales Alenia Space group. Before explaining what these tools are and what they will do, let's see a quick recap of the mission, starting with the destination. Jupiter, the largest planet in the solar system (some call it a failed star, precisely because of its size), has (at least) 79 natural satellites: among these, Io , Europa , Ganymede and Callisto are the largest and most interesting . Io is the closest of the four to Jupiter, is covered in sulfur compounds and lava products, and is the most volcanically active body in the Solar System, due to the enormous gravity of the planet it orbits. However, it is not part of Juice's objectives, for technical reasons: "Even though Io is extremely interesting – explained Giulio Pinzan , who is part of Juice's flight controller team for ESA – it will not be 'visited' by Juice: it will not it is an icy moon, and since it is very close to Jupiter it has too strong a magnetic field, which would make the instruments on board difficult". The situation is different for the other three moons: Europa, Ganymede and Callisto are icy moons, and it is thought that an ocean of liquid salt water is hidden under the crust of Europa, which could make it - at least in principle - a good candidate to host (or have hosted) life forms.** **Ganymede, for its part, is the largest satellite in the Solar System, and is endowed with an intense tectonic activity, also due to the gravitational interaction with Jupiter ; and even Callisto, a body riddled with craters, could host underground oceans of liquid salt water.
The mission: milestones and challenges
The mission is extremely demanding, for various reasons . First of all, the distance to the destination: between Jupiter and the Earth there are (on average) about 700 million kilometres, which entails a series of non-indifferent signals takes more than an hour and a half, so the vehicle must be as autonomous as possible) and energy (the distance from the Sun is such that the energy collected by the solar panels is just 4% of that which would be collected on Earth ). Then there is the problem of temperature swings – Juice will go from 125 °C to -230 °C, and all its instruments must be able to withstand this temperature swing – in addition to that of cosmic rays and the aforementioned strong magnetic field. Nonetheless, its designers are convinced that it can be done: "After the take-off of the rocket that will carry Juice into Space [an Arian V, ed.] – continues Pinzan – the probe will take about eight years to reach Jupiter. The distance from the planet is such that it will take four gravitational slingshot maneuvers (three on Earth, one on Venus) to launch Juice on the right trajectory.If all goes as planned, it will reach Jupiter in July 2031; if months before entering orbit, the science phase will begin nominal" . The probe will spend many months in orbit around Jupiter, completing 35 fly-bys around Europa, Ganymede and Callisto and finally, in 2034, entering the orbit of Callisto and thus becoming the first artificial satellite to orbit another moon planet.
The instruments on board
As we said, much of the technology on board Juice is Italian, the result of collaboration between academia, research institutions and private individuals. One of the instruments we had the opportunity to see (or rather, its clone used for testing, since the original is already in Kourou) is called Janus , and it is a high-resolution camera for monitoring the atmosphere of Jupiter and for the in-depth study of its icy moons. It has a resolution such as to be able to observe a tennis ball from a kilometer away, and is equipped with a wheel with 13 different color filters, which will allow your eye to detect concentrations of different chemical elements (for example, red can reveal the presence of methane and yellow the presence of sodium). The counterpart of Janus , which is essentially a huge telephoto lens, is called Majis , the result of a bilateral agreement between ASI and CNES, and is a hyperspectral camera that allows you to observe and characterize clouds, ice and minerals on the surfaces of the three moons: it is consisting of two instruments in one that cover a total of the range from the visible to the mid-infrared, and is equivalent to having 1016 cameras each of which captures the image in a single color. By suitably combining these images it is possible to identify the minerals that make up the surface of solid bodies and the gases present in their atmospheres, also measure density, temperature, movements and so on. Also worthy of mention are Juice's photovoltaic panels, the largest ever built for an interplanetary mission (once deployed they will have a total surface area of about 85 m 2 ), and the Rime instruments (a radar capable of detecting the internal structure of icy layers) and 3GM, an eye that can peer even deeper by analyzing variations in the gravitational field.
