The Amazing JUICE Mission: Insights from PM Giuseppe Sarri (Part 2)
Welcome back to the second part of our exclusive interview with Giuseppe Sarri, where he delves deeper into the remarkable systems that make the JUICE spacecraft an extraordinary feat of engineering. In Part 1, we explored the mission’s goals and the path it will take to reach its destination. Now, let’s take a closer look under the hood of this Jovian explorer.
One of the key features of the JUICE spacecraft is its impressive instrument suite, which comprises ten instruments. Developed in Europe with contributions from the United States, Israel, and Japan, these instruments can be categorized into three main groups: remote sensing, geophysics, and in situ particles and fields. Each category will investigate different aspects of Jupiter and its moons, including geology, topography, gravity fields, cloud morphology, atmospheric chemistry, and magnetic and plasma environments. Additionally, a radiation monitor will provide valuable information on electron, proton, and heavy ions.
However, powering such an advanced instrument suite in the vast expanse of space comes with its challenges. As Jupiter is over five times further away from the Sun than Earth, the intensity of sunlight is only 1/25th of what it is on our planet. To ensure that JUICE receives the necessary power, state-of-the-art solar cell technology is used, requiring a large solar array. Initially designed to have an overall surface area of over 100 m2, technical considerations ultimately led to a slightly smaller size of 85 m2. This results in a spacecraft that spans nearly 30 meters when its wings are fully deployed.
Despite the size of its solar panels, JUICE will generate relatively little power once it reaches Jupiter. To operate its subsystems and instruments, the spacecraft will rely on batteries with a capacity of 6 kWh, while the solar array will generate just 800 W at the end of its life. To put this into perspective, that’s less power than an average microwave oven requires.
The design of the solar arrays underwent meticulous trade-offs to ensure they were compatible with the spacecraft’s overall mass, the power consumption of the electronic units, the size of the battery, and the Attitude and Orbit Control System. As the solar array accounts for approximately 17% of the spacecraft’s dry mass, its dimensions and shape were carefully considered. Similarly, each electronic unit was designed to minimize power consumption, and strict power requirements were imposed on all instruments. Balancing these factors required increasing the size of the battery while decreasing the size of the solar array.
Another remarkable feature of JUICE is its communication system. The spacecraft boasts a large 2.5-meter diameter High Gain Antenna, crucial for downloading science data. During the initial design phase, it was decided to have the antenna fixed on the body of the spacecraft rather than having a steerable antenna. While a steerable antenna would have allowed for continuous communication with Earth, it also posed the risk of mission failure if the steering mechanism malfunctioned. To mitigate this risk, a smaller steerable antenna was added to maintain contact with Earth throughout the mission. The large antenna dish will also serve as a sunshield when the spacecraft passes Venus during its eight-year tour of the solar system.
Additionally, JUICE features a 16-meter long dipole antenna called RIME (Radar for Icy Moons Exploration), which will sound the subsurface of icy moons to detect liquid water. To ensure accurate readings, this antenna is positioned far from the spacecraft using a boom that spans just over 10 meters. The geophysical package of instruments also includes a laser altimeter and a radio science instrument, which work in conjunction with RIME to provide a comprehensive understanding of the interior of these moons. The successful deployment of these mechanisms in orbit is a testament to the meticulous planning and engineering prowess behind the JUICE mission.
Following its launch in April, the JUICE spacecraft underwent a three-month period of thorough in-orbit verification, known as commissioning. This critical phase was concluded on July 19th with an ESA high-level review, confirming that all systems and instruments were functioning nominally and that the program development phase was completed. After the first Deep Space Manoeuvre in November, the spacecraft is now on course for its long journey to Jupiter and its icy moons.
To learn more about the incredible story and the people behind the JUICE mission, the European Space Agency has released a movie titled “The Making of Juice.” This captivating documentary provides an in-depth look at the behind-the-scenes efforts that have brought this ambitious mission to life.
In conclusion, the JUICE spacecraft is an awe-inspiring endeavor that pushes the boundaries of planetary exploration. With its powerful instrument suite, innovative solar array design, and advanced communication system, JUICE is poised to unlock the mysteries of Jupiter and its enigmatic moons. As we eagerly await its arrival at its final destination, we can only imagine the groundbreaking discoveries that lie ahead.
