The European Space Agency’s Jupiter Icy Moons Explorer (JUICE) swung past Earth on Monday, Sept. 28, to pick up a gravity assist that will increase its speed by roughly 7,830 mph (3.5 km/s) and bend its trajectory by about 20 degrees. The brief encounter, which took place over the Indian Ocean at approximately 7:45 a.m. EDT (11:45 GMT), marks the third gravity‑assist maneuver of JUICE’s three‑and‑a‑half‑year journey to the Jovian system.
Mission background and previous assists
JUICE launched in April 2023 with the objective of studying Jupiter’s icy moons, particularly Ganymede. During its cruise phase, the probe has relied on planetary flybys to conserve fuel and achieve the high velocities needed for a 2031 arrival at Jupiter. The first assist occurred in August 2024 when JUICE performed the inaugural lunar‑Earth flyby, using the Moon’s gravity to set up a close Earth pass the following day. A second assist followed in August 2025, when the spacecraft swung by Venus, gaining both speed and a trajectory change.
Details of the September 2028 Earth flyby
During the latest maneuver, JUICE approached Earth to a distance of 5,370 miles (8,640 km). ESA engineers carefully planned the pass to avoid any risk of collision with Earth‑orbiting satellites. Claire Vallat, JUICE Project Scientist, emphasized the operational simplicity of this flyby compared with the 2024 lunar‑Earth sequence, noting that “all flybys are risky, requiring very careful planning and continuous monitoring. But the upcoming Earth flyby is much simpler from an operational perspective.” She added that the maneuver “is great news for science, because it means we will be able to turn JUICE in all different directions to point its science instruments at different parts of Earth and the moon.”
The gravity assist will not only add roughly 7,830 mph to JUICE’s velocity but also rotate its flight path by about 20 degrees. This change is essential for the spacecraft to remain on a trajectory that allows a fuel‑efficient insertion into Jupiter’s orbit in 2031, and later a transition to a dedicated Ganymede orbit in 2034.
Future flybys and mission timeline
After the September 2028 encounter, JUICE is scheduled for a third and final Earth gravity assist in January 2029. The cumulative effect of these assists will preserve enough propellant for the spacecraft to decelerate upon arrival at Jupiter, preventing it from simply passing through the system at high speed. The mission’s long‑term plan calls for JUICE to enter Jupiter’s orbit in 2031, conduct extensive observations of the planet’s magnetosphere, and then move into a dedicated orbit around Ganymede three years later.
JUICE’s journey demonstrates how strategic use of planetary gravity can extend the capabilities of deep‑space missions while minimizing onboard fuel requirements. The successful Earth flyby underscores ESA’s meticulous planning and the robustness of the spacecraft’s navigation systems, keeping the mission on track for its ambitious scientific goals.
Helene Elliott is the Lead Science & Space Reporter at News Raise. She reports on aerospace missions, astrophysics discoveries, quantum research, and environmental technology.
