JUICE, the short form for Jupiter Icy Moons Explorer, is a spacecraft created by the European Space Agency (ESA) to investigate Jupiter and its three largest moons: Ganymede, Callisto, and Europa. Juice will return to Earth on August 19–20. Flight controllers will direct the spacecraft past the Moon and then past Earth. Juice will be directed to Jupiter via Venus through this “braking” maneuver.
What is happening?
This is the first ever lunar-Earth flyby and double gravity assist maneuver. It can change Juice’s speed and direction to alter its route through space, but it is risky; the slightest error could send Juice off course and end the mission.
Juice, launched in April 2023, will begin its trip to Jupiter with a flyby of the Moon and Earth.
Earth will bend Juice’s trajectory through space during the flyby, ‘braking’ it and guiding it towards a flyby of Venus in August 2025. From that point on, the energy boosts will commence, with Juice being whizzed up by Venus and then twice by Earth – the space exploration equivalent of sipping three espressos in succession.
Why does it have to happen?
Jupiter is, on average, 800 million kilometers away from Earth. Without a large rocket, sending Juice directly to the massive planet would require an unattainable 60000 kg onboard propellant. Juice would need to carry an enormous quantity of propellant to slow itself down enough to enter orbit around Jupiter once it arrives, rather than simply speeding by and disappearing into space.
So Juice is taking the leisurely road, utilizing the gravity of other planets to carefully modify its trajectory across space, ensuring it arrives at Jupiter at the proper speed and angle. Over the previous two decades, Juice’s dedicated mission analysis team has meticulously designed this extremely intricate, ever-changing route.
Surprisingly, slowing Juice down during the lunar-Earth flyby is more efficient than speeding it up. If ESA had used this flyby to propel Juice toward Mars, it would have had to wait a long time for the next planetary flyby.
The initial braking maneuver allows ESA to shortcut through the inner solar system.
How does ESA make this happen?
Mission operators have already altered Juice’s path to guarantee that it arrives at the Moon first, then to Earth a day later, at precisely the appropriate timing, speed, and direction. They are optimistic that they will succeed, but this is a perilous undertaking that no previous space mission has ever encountered.
Ignacio Tanco, Juice’s Spacecraft Operations Manager, describes it as, “It’s like passing through a very narrow corridor, very, very quickly: pushing the accelerator to the maximum when the margin at the side of the road is just millimeters.”
Juice will pass incredibly close to both the Moon and Earth, necessitating real-time pinpoint accuracy in all navigation maneuvers. From August 17 to 22, Juice will maintain constant touch with ground stations across the world. Every second of the way, day and night, operators will keep a close eye on the data flowing down from Juice, making any necessary adjustments to keep the spacecraft on target.
Additional stuff!
As if guiding Juice through two massive space barriers wasn’t enough, ESA will also activate the spacecraft’s ten science equipment as it passes by the Moon and Earth.
The lunar-Earth flyby provides an ideal testing environment for sensor teams to acquire and analyze data from a genuine surface in space for the first time. For some sensors, this is the only opportunity to take specific measurements during Juice’s eight-year journey to Jupiter. It will allow scientists and engineers to calibrate their devices, iron out any remaining flaws, and who knows, they might even make some unexpected scientific findings.
The lunar-Earth flyby is especially important for Juice’s RIME (Radar for Icy Moon Exploration) instrument. Some electronic noise within the spaceship disturbs the RIME data.
The August 19 Moon pass is one of just a few opportunities for the RIME team to assess how this noise affects the instrument’s performance before arriving at Jupiter. During the closest approach to the Moon, RIME will have eight minutes to view alone, with all other instruments turned off or in quiet mode. Based on these discoveries, the RIME team will develop an algorithm to address the noise issue.
More about Juice
JUICE, which was launched on April 14, 2023, is currently on an eight-year mission to Jupiter. It will reach the gas giant in July 2031 and conduct at least four years of research on the planet and its moons.
JUICE is the debut large-class mission in the Cosmic Vision 2015-2025 program of the ESA. It is also the first interplanetary spacecraft to reach the outer Solar System planets that was not launched by the United States and the first to orbit a moon other than Earth’s Moon.
What was it doing for the past one year?
Although JUICE has embarked on a lengthy, eight-year journey, the year following its launch was not without its challenges. It is continuously drifting away from Earth. The crew at ESA was occupied with inspecting all onboard systems and instruments on JUICE. This entailed verifying that all systems were functioning adequately following the launch and the initial journey. Additionally, they calibrated the scientific instruments to guarantee they would generate precise data upon JUICE’s arrival at Jupiter. The trajectory of JUICE toward its forthcoming gravity assist with the Moon and Earth may have been refined through minor course corrections or maneuvers. The spacecraft’s health and performance were continuously monitored by the crew, who were also preparing for future operations and the upcoming Earth-Moon flyby.