Image: © ESA
In a world-first, the spacecraft completed a high-risk slingshot manoeuvre around the moon and Earth to take a shortcut to Jupiter.
The Jupiter Icy Moons Explorer (Juice) mission has been successfully rerouted following the first-ever lunar-Earth flyby, which went off “without a hitch”.
The European Space Agency (ESA) said the spacecraft is now Venus-bound following the tricky manoeuvre.
Ignacio Tanco, spacecraft operations manager for the mission, said the team was thrilled to see Juice come so close to Earth. “The gravity assist flyby was flawless, everything went without a hitch,” he said.
The lunar-Earth flyby is the first major manoeuvre since Juice’s launch in April 2023 and is designed to reroute the spacecraft’s path to Jupiter.
The closest approach to the moon was at 9.15pm UTC on 19 August, while it came closest to Earth a little more than 24 hours later at 9.56pm UTC on 20 August.
A close-up of the moon taken by Juice’s monitoring system. Image: © ESA/Juice/JMC
According to the ESA, Juice has a little extra propellant in its tanks to get closer to Jupiter’s moon Ganymede than originally planned.
“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,” added Tanco.
The flyby allowed Juice to use the gravity of the moon and then the Earth to bend its’s trajectory through space, ‘braking’ it and redirecting it. It is now on course for another flyby of Venus in August 2025.
That Venus flyby will boost Juice back out towards Earth, arriving in September 2026 and again in January 2029 to gain two more boosts before arriving at Jupiter in July 2031.
As well as providing a shortcut to Jupiter, the lunar-Earth flyby also allowed researchers to test out Juice’s scientific instruments in space.
“It happens early enough in Juice’s journey that we can use the data to prepare the instruments for arrival at Jupiter,” said Dr Claire Vallat, Juice operations scientist. “Given how well we know the physical properties of Earth, the moon and the surrounding space environment, it’s also the ideal location to understand how the instruments respond to a real target.”
Also benefitting from the flyby is a team of three researchers in Ireland, who used the flyby to test their ideas about the spacecraft’s behaviour in the environment of a moon, in preparation for the flybys of Jupiter’s moons.
Among them is Prof Caitriona Jackman, who said the encounter with Earth’s moon is a “practice-run” for studying Jupiter’s moons. “I’m extremely proud of the work carried out by our research group so far, and that we can be part of such an important mission,” she said ahead of the flyby.
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