The European Space Agency’s JUICE space probe (Jupiter Icy Moons Explorer) has completed a historic, first flyby of its kind of the Earth and the Moon.
Launched on April 14, 2023, the probe is now heading for a flyby of Venus, the second planet from the Sun, and will return to Earth for further gravity assist in 2026 and 2029. After these flybys, JUICE will continue on to Jupiter and its moons, and is expected to reach its final destination in July 2031.
“The gravity-assist flyby went flawlessly. Everything went smoothly and we were thrilled to see Juice return so close to Earth,” said Ignacio Tanco, JUICE spacecraft operations manager, in a statement.
JUICE arrived at our Moon for its flyby on Monday (19 August) at 18:15 EDT (21:15 UTC); this rendezvous led the ESA spacecraft toward Earth. It arrived at our planet just over 24 hours later, on Tuesday (20 August) at 18:56 EDT (21:56 UTC). Planetary and moon flybys are crucial to JUICE’s journey to Jupiter, as the gravitational tides of these objects can help catapult the spacecraft toward its final destination, allowing trajectory changes with minimal fuel consumption.
At its closest approach to Earth, JUICE hovered about 6,840 kilometers above Southeast Asia and the Pacific Ocean. The spacecraft also took the opportunity to take pictures of our home planet with its onboard cameras, just as it had photographed the Moon the day before.
Related: Telescopes capture JUICE probe near Jupiter during historic flyby of Earth and Moon (photos)
Both flybys were specifically aimed at reducing JUICE’s speed. The flyby of the Moon slowed the spacecraft by about 3,219 kilometers per hour, and the subsequent flyby of Earth slowed it by about 17,220 km/h. They actually put JUICE on its new trajectory toward Venus by diverting the spacecraft’s trajectory by 100 degrees from its approach path.
The risky flyby required highly precise real-time navigation, but saved a total of around 150 kilograms of fuel. This ensured that JUICE had enough fuel to get closer to Jupiter’s moon Ganymede than originally planned.
Preparations for this risky maneuver began last month, when ESA operators gave JUICE gentle nudges to put it on the right path to the Moon and Earth. They then tracked the spacecraft’s progress between 17 and 22 August. “Thanks to the very precise navigation by ESA’s flight dynamics team, we managed to use only a tiny fraction of the fuel reserved for this flyby,” explained Tanco. “This will increase the margin we have for rainy days or to extend the science mission after arriving at Jupiter.”
While the main objective of the JUICE flyby between the Moon and Earth was to redirect the spacecraft, it also enabled ESA operators to perform some preliminary checks on the scientific instruments on board the spacecraft.
JUICE’s full set of ten instruments was available for the lunar approach, while eight were online when the ESA spacecraft passed by Earth. ESA has announced that it plans to release the scientific data collected during these flybys in the near future. This will include more high-resolution images from JUICE’s JANUS camera.
“The timing and location of this double flyby will allow us to closely study the behavior of JUICE’s instruments,” explained Claire Vallat, the spacecraft’s operations scientist. “It will take place early enough in JUICE’s journey that we can use the data to prepare the instruments for arrival at Jupiter.”
“And given our extensive knowledge of the physical properties of the Earth, the Moon and the surrounding space environment, it is also the ideal place to understand how the instruments respond to a real target.”
