A spacecraft launched last year is set to execute a groundbreaking manoeuvre as it embarks on its journey to Jupiter. The European Space Agency’s (ESA) Juice probe, which blasted off in April 2023, will perform a world-first double gravity assist manoeuvre next month. This innovative technique involves the spacecraft flying past Earth and the Moon to utilize their gravitational forces, thereby saving fuel on its extended voyage through the Solar System.
Currently positioned 10 million kilometres from Earth, the six-tonne Juice spacecraft is scheduled to make its approach on August 19-20. By leveraging the gravity of both Earth and the Moon, Juice aims to gain a boost that will facilitate its eight-year trek to Jupiter. This technique is crucial as the Ariane 5 rocket used for the launch did not possess sufficient power to take a direct route to Jupiter, which is approximately 800 million kilometres away. Direct travel would have necessitated carrying 60 tonnes of propellant, whereas Juice only has three tonnes onboard.
ESA’s space operations centre in Darmstadt, Germany, has been preparing for this complex manoeuvre for weeks. The spacecraft will cross 750 kilometres above the Moon on August 19 before passing Earth the next day. This flyby is expected to increase Juice’s velocity to 3.3 kilometres per second, compared to the 3 kilometres per second it would achieve without the Moon’s assist. As it speeds past, Juice will also capture images and test its scientific instruments.
This mission represents the first instance of a spacecraft using consecutive gravitational assists from two celestial bodies. Juice’s successful flyby will mark a historic achievement in space exploration. The spacecraft will then head towards Venus for another gravity assist in 2025, followed by two additional Earth flybys in 2026 and 2029.
Upon reaching Jupiter in July 2031, Juice will undertake a series of 35 gravitational assists around Jupiter’s moons. This phase of the mission will require precise navigation, with the spacecraft’s trajectory resembling a complex “plate of spaghetti” due to the multiple gravity boosts. The intricate planning and execution of these manoeuvres are critical to Juice’s mission to explore Jupiter’s icy moons, which may harbor conditions suitable for extraterrestrial life.
