April 14, 2023

— An interplanetary probe is now on its way to "squeeze" out all it can about Jupiter and three of its large ocean-bearing moons.

The European Space Agency (ESA) launched its Jupiter Icy Moons Explorer, or JUICE, mission on Friday (April 14). The probe lifted off atop an Arianespace Ariane 5 ECA rocket from Europe's Spaceport in Kourou, French Guiana at 8:14 a.m. EDT (1214 GMT or 9:14 a.m. local time).

The successful ascent marked the last ESA mission to launch on an Ariane 5 and the overall penultimate flight for the rocket, which is scheduled to fly for the last time in June. The Ariane 5, which made its first flight in 1996, is being replaced by the next-generation Ariane 6.

JUICE will study three of Jupiter's largest moons — Callisto, Europa and, in particular, Ganymede — using a suite of instruments that will focus on the moons as both planetary objects and as possible locations for the presence of life. The mission will also observe Jupiter's complex environment in depth.

"The main goal is to understand whether there are habitable environments among those icy moons," said Olivier Witasse, ESA's JUICE project scientist, during a press briefing on April 6. "We will characterize in particular the liquid water oceans which are inside the icy moons."

After arriving at Jupiter in July 2031 and performing 35 flybys of the three moons over the course of three years, JUICE will become the first ever spacecraft to orbit a moon other than Earth's, Ganymede, in December 2034.

Journey to Jupiter

JUICE launch to Jupiter. Click to view and enlarge video in a new pop-up window. (ESA)

Accompanying JUICE on its ride off of Earth was an enlarged version of a child's drawing. The imaginative design was created by a ten-year-old Ukrainian girl, Yaryna, whose artwork was selected from of the more than 2,600 entries from 63 different countries that were received as part of a "Juice Up Your Rocket" contest.

"It is so cute, cheerful and genuine," said JUICE engineer Manuela Baroni in a statement released by ESA. "It contains the main elements of the mission — Jupiter, the icy moons, and JUICE itself, but we love that it also contains Earth, highlighting the huge amount of effort that we are all putting in. We also chose it because of the clear lines and colors that would show up well at the top of the rocket. We can now see that it was definitely the right choice."

Twenty-six minutes after leaving the ground, JUICE left its Ariane 5 upper stage behind, beginning the journey to Jupiter. At about an hour and a half after launch, the spacecraft's solar arrays are set to be deployed, followed by its antennae, probes and magnetosphere boom over a planned course of the next 17 days.

From there, JUICE begins on a course that will use Earth, the moon and Venus to reach Jupiter. On its first swing-by, expected in August 2024, JUICE will become the first spacecraft to use both Earth and the moon's gravity to assist its trajectory and save propellant.

"This will be the most accurate gravity assist maneuver ever done," Alessandro Atzei, JUICE team member and ESA scientist, said in the pre-launch briefing. "But this, I think, is under control."

From pulp to JUICE

JUICE will be the 11th spacecraft to visit Jupiter and the fourth to enter the gas giant's orbit. That count includes NASA's Europa Clipper, a mission that will not launch until October 2024, but will overcome JUICE and arrive at Jupiter in 2030.

JUICE is also the seventh interplanetary mission launched by ESA.

But the Jupiter Icy Moons Explorer carries even a greater legacy forward, both literally and figuratively. One of the exterior sheets of multi-layered insulation that makes up the thermal blanket wrapped around JUICE also doubles as a plaque celebrating Italian astronomer Galileo Galilei's discovery of Jupiter's four largest moons — including the mission's three targets.

"It's not only an opportunity to pause and reflect on the decades-long hard work that has gone into conceiving, building and testing the spacecraft, but also to celebrate the curiosity and wonder of everyone who's ever gazed up at Jupiter in the night sky and pondered our origins — the inspiration behind this mission," Giuseppe Sarri, ESA's Juice project manager, said at the plaque's unveiling in January.

The plaque features imagery of Galilei's first Jovian observations reproduced from the "Sidereus Nuncius," which is hosted in the library of the Astronomical and Copernican Museum at the headquarters of the Istituto Nazionale di Astrofisica (INAF) in Rome, Italy. The copy is one of the first 550 printed in 1610 in Venice.