JUICE Completes Third Earth Gravity Assist
The European Space Agency’s (ESA) Jupiter Icy Moons Explorer (JUICE) completed its third Earth gravity assist on 28 September 2026. The spacecraft passed approximately 8,640 km above Earth over the Indian Ocean, using Earth’s gravity to alter its trajectory by about 20 degrees. The manoeuvre is an important step in JUICE’s long journey towards the Jupiter system and demonstrates how planetary gravity can be used to efficiently navigate deep-space missions.
What is a Gravity Assist?
A gravity assist, also known as a slingshot manoeuvre, is a spacecraft technique that uses the gravity and motion of a planet or moon to change the spacecraft’s speed and direction.
Instead of relying entirely on onboard fuel, a spacecraft can gain or lose energy during a carefully planned planetary flyby. This technique helps reduce fuel requirements and makes long-duration interplanetary missions more efficient.
JUICE Mission
JUICE stands for Jupiter Icy Moons Explorer. It is an ESA mission designed to study Jupiter and its large icy moons, particularly Ganymede, Europa and Callisto.
Ganymede is the principal target of the mission and is the largest moon in the Solar System.
JUICE is planned to enter orbit around Jupiter in 2031 and subsequently enter orbit around Ganymede in 2034. The mission will investigate the moons’ surfaces, interiors, atmospheres and potential habitability.
2026 Earth Flyby
During the September 2026 Earth flyby, JUICE gained approximately 12,606 km/h (3.5 km/s) in speed.
Mission controllers needed only one small course correction before the encounter. Such corrections are part of normal spacecraft navigation and help ensure that a planetary flyby occurs along the intended trajectory.
The spacecraft’s passage over the Indian Ocean provided the required gravitational interaction to modify its trajectory towards the outer Solar System.
Importance of Earth Flybys
Earth gravity assists are particularly useful for missions travelling towards distant planets. By repeatedly using planetary flybys, spacecraft can accumulate the velocity required to reach their destinations while conserving onboard propellant.
NASA’s Juno spacecraft, for example, also used an Earth gravity assist on 9 October 2013 before reaching Jupiter.
JUICE Mission: Important Facts for Exams
- Mission: Jupiter Icy Moons Explorer (JUICE)
- Agency: European Space Agency (ESA)
- Third Earth gravity assist: 28 September 2026
- Closest altitude: Approximately 8,640 km above Earth
- Location: Over the Indian Ocean
- Trajectory change: About 20 degrees
- Velocity gained: Approximately 12,606 km/h or 3.5 km/s
- Jupiter arrival: Planned for 2031
- Ganymede orbit: Planned for 2034
- Ganymede: Largest moon in the Solar System
- Gravity assist: Also known as a slingshot manoeuvre
