The European Space Agency’s Jupiter Icy Moons Explorer (JUICE) is heading back to Earth — in the intervening time, anyway.
On Nov. 17, JUICE performed a 43-minute burn to get into position for its upcoming Earth-moon flyby, the first-ever double gravity assist of the 2 celestial bodies. It was the spacecraft’s largest maneuver thus far. “This maneuver used up roughly 363 kilograms [800 pounds] of fuel – or almost exactly 10% of the three,650 kilograms [8,047 pounds] of fuel that JUICE launched with,” Julia Schwartz, Flight Dynamics Engineer at ESA’s ESOC mission control center in Germany, said in a statement.
The spacecraft launched from French Guiana on April 23, 2023, and is ultimately sure for Jupiter to check the planet and three of its icy, potentially oceanic, moons: Ganymede, Callisto, and Europa. But with the intention to get there, it must perform a series of gravity assists, flying past the planets of the inner solar system and using their gravitational tides to slingshot itself toward its goal — a method that saves overall fuel.
This burn is considered one of two crucial to place JUICE on the best trajectory for the Earth-moon gravity assist, the primary within the series of assists, which is able to occur in Aug. 2024. “This primary burn did 95% of the work, changing JUICE’s velocity by almost 200 meters per second [656 feet per second],” said Schwartz. “JUICE is considered one of the heaviest interplanetary spacecraft ever launched, with a complete mass of around 6,000 kilograms [13,228 pounds], so it took loads of force and loads of fuel to attain this.”
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In the approaching weeks, ESA will analyze JUICE’s latest orbit before calibrating a second burn to fine-tune the probe’s trajectory for the double gravity assist. “If all goes well with each parts of this maneuver, we likely won’t need to make use of the fundamental engine again until we enter orbit around Jupiter in 2031,” Ignacio Tanco, JUICE Spacecraft Operations Manager, said in a press release. “For small trajectory corrections between from time to time, we are going to use JUICE’s smaller thrusters.”
This primary burn was a very difficult one, as parts of it couldn’t be tested upfront. “For instance, we only had an estimate for the way the liquid within the fuel tanks will move around because the spacecraft accelerates,” said Tanco. “This may be very essential to know precisely, because if the fuel behaves different to how we expect, it could cause the spacecraft to drift astray through the burn. So, we’re monitoring closely.”
The team will use data from this burn to assist inform future burns for the probe’s Jupiter insertion, when JUICE might want to decelerate by roughly one kilometer per second (0.62 miles per second) to enter Jovian orbit ultimately.
For now, it is a waiting game to see if JUICE is headed back our way.