ESA’s Jupiter Icy Moons Explorer (Juice) launched on 14 April 2023 on an eight-year journey to the largest planet in the Solar System.

On the way, it will carry out a series of gravity assist manoeuvres, exchanging energy with the planets to reduce the amount of fuel it needs to carry to make the trip.

On 19—20 August 2024, Juice will carry out the first of these gravity assists. However, this manoeuvre won’t just be a first for Juice, or even for ESA, it will be a first for any spacecraft, ever.

Juice’s combined ‘lunar-Earth gravity assist’ (LEGA) will see the spacecraft swing past the Moon just a few hundred km from the surface, and then past Earth just a few thousand km from the surface almost exactly 24 hours later.

Using the gravity of the Moon to fine tune the much larger gravity assist at Earth will boost the efficiency of Juice’s journey, but the double flyby requires ultra-precise spacecraft operations.

Some of Juice’s cameras and science instruments will also be switched on as the spacecraft sweeps past the Moon and Earth to help test and calibrate them for their scientific activities in the Jupiter system.

Juice officially entered its ‘LEGA phase’ on 24 June, kicking off weeks of activity at ESA as the spacecraft’s operations and science teams prepare for this unique manoeuvre.

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