The Juice spacecraft from the European Space Agency (ESA) has completed a unique lunar-Earth flyby. It used Earth's gravity to set course for Venus, taking a faster route toward Jupiter.
On August 20, at 2:45 AM (India time), Juice made its closest pass by the Moon. This manoeuvre set it on course for its closest approach to Earth a little over a day later, on August 21, at 3:26 AM (India time).
During its flyby, just 6,840 km above Southeast Asia and the Pacific Ocean, Juice used most of its instruments to capture images and gather scientific data.
The flyby aimed to adjust Juice's journey using the Moon's and Earth's gravitational pull. Initially, the Moon's gravity boosted Juice's speed, sending it toward Earth.
Then, Earth's gravity slowed the spacecraft, redirecting it toward Venus. This manoeuvre altered Juice's course by 100 degrees from its original path.
The spacecraft’s flyby, although risky, was executed with great precision, saving about 100-150 kg of fuel. Leading up to the flyby, operators made small adjustments to ensure the correct path, monitoring the spacecraft constantly from August 17-22.
The launch in April 2023 left Juice with extra fuel, allowing it to approach Jupiter’s moon Ganymede more closely than first expected. The successful flyby secured this additional scientific opportunity.
“Thanks to very precise navigation by ESA’s Flight Dynamics team, we managed to use only a tiny fraction of the propellant reserved for this flyby. This will add to the margins we keep for a rainy day, or to extend the science mission once we get to Jupiter,” said Ignacio Tanco, Spacecraft Operations Manager for the mission.
The spacecraft is on course to meet Venus in August 2025. This encounter with Venus will propel the spacecraft back toward Earth for additional flybys in September 2026 and January 2029, each providing the necessary momentum to reach Jupiter by July 2031 eventually.
