JUICE launched in April 2023 and is taking a winding eight-year path to reach Jupiter. It will not arrive until July 2031 — but along the way it has already made history with the first-ever combined Moon-Earth flyby. To learn about Jupiter itself, see the main Jupiter pillar.
JUICE is the European Space Agency’s spacecraft heading to Jupiter’s icy moons. It launched on 14 April 2023 and is scheduled to arrive at Jupiter in July 2031. JUICE will study Ganymede, Callisto and Europa — the three Galilean moons thought to have hidden oceans — and is planned to eventually orbit Ganymede. If successful, it will become the first spacecraft ever to orbit a moon other than Earth’s Moon.
Find Jupiter in the night sky and look at it with binoculars. You should see the four big Galilean moons — the same moons JUICE is going to study. Three of them (Ganymede, Callisto, and Europa) are JUICE’s main targets. The closest one to Jupiter, Io, is too radiation-blasted for JUICE to visit closely.
📋 JUICE — Quick Facts
- Mission nameJUICE — JUpiter ICy moons Explorer
- AgencyEuropean Space Agency (ESA), with contributions from NASA, JAXA, and the Israel Space Agency
- ManufacturerAirbus Defence and Space
- Launched14 April 2023 — Kourou, French Guiana
- RocketAriane 5 (its second-to-last flight)
- Spacecraft massAbout 6,000 kg (13,230 lb) at launch — one of the heaviest interplanetary spacecraft ever launched
- Solar panel span27 m (89 ft) when fully extended
- Lunar-Earth flyby19–20 August 2024 ✅ — a world first (Moon, then Earth, in a single manoeuvre)
- Venus flyby31 August 2025 ✅
- Next Earth flybySeptember 2026 (planned)
- Final Earth flybyJanuary 2029 (planned)
- Scheduled Jupiter arrivalJuly 2031
- Planned Ganymede orbit insertionDecember 2034 — if successful, a first in spaceflight history
- Main targetsGanymede (main focus), Callisto, Europa — the three ocean-bearing Galilean moons
- Science instruments10 — including ice-penetrating radar, magnetometer, laser altimeter, and cameras
JUICE will not land on Jupiter’s moons. It is planned to orbit Jupiter, then later orbit Ganymede — always from above the surface. There are no plans to put the spacecraft on the ground of any moon.
What is JUICE?
JUICE stands for JUpiter ICy moons Explorer. It is a robotic spacecraft built by the European Space Agency to study three of Jupiter’s big icy moons: Ganymede, Callisto, and Europa. All three are thought to hide huge salty oceans under their icy crusts — and JUICE is going there to look much more carefully than any spacecraft before.
JUICE was built by Airbus Defence and Space in Europe. ESA leads the mission, with contributions from NASA, the Japanese space agency (JAXA), and the Israel Space Agency. More than 80 companies from across Europe worked on the spacecraft.
JUICE is one of the heaviest interplanetary spacecraft ever launched — about 6,000 kg at takeoff, with massive solar panels spanning 27 metres when fully extended. Like NASA’s Europa Clipper, JUICE needs huge solar panels because sunlight at Jupiter is about 25 times weaker than at Earth.
OCEAN-BEARING MOON — a moon that scientists think has liquid water hidden inside, usually under a thick icy crust. Ganymede, Callisto, and Europa are all believed to be ocean-bearing moons — and JUICE is going to study all three.
Why send JUICE to Jupiter?
The big idea behind JUICE is habitability. Just like NASA’s Europa Clipper, JUICE is looking at whether Jupiter’s icy moons have the right conditions for life — not searching for living things directly, but checking whether life could exist in those hidden oceans.
JUICE has four main goals:
- Map Ganymede in detail — the biggest moon in the solar system, and the only moon with its own magnetic field
- Study Callisto’s ancient surface — the oldest surface in the Jupiter system, like a time capsule
- Investigate Europa’s ice — looking for signs of activity and possible places where the ice might be thin
- Understand Jupiter’s system — the planet’s atmosphere, magnetic field, and how the moons interact with it
Together with NASA’s Europa Clipper, JUICE is part of the most ambitious effort ever to study Jupiter’s ocean moons. The two missions are like teammates: Europa Clipper focuses on Europa, JUICE focuses on Ganymede (and visits Europa and Callisto along the way).
JUICE is not looking for aliens or living things directly. It is a habitability mission — designed to check whether Jupiter’s ocean moons have the right water, energy, and chemistry for life. Even if JUICE finds perfect conditions, that does not mean it found life. A future, different mission would be needed for that.
JUICE’s long journey to Jupiter
JUICE is one of the heaviest spacecraft ever sent into deep space — too heavy to fly directly to Jupiter using just its engine. Instead, it takes an eight-year, looping path through the inner solar system, using the gravity of other planets to give it a boost each time. This is called a gravity assist.
Stage 1: Lunar-Earth flyby — 19–20 August 2024 ✅
JUICE’s first manoeuvre was a world first: flying past the Moon and then past Earth within just 36 hours. No spacecraft had ever done that before. Picking up speed from both the Moon and Earth saved JUICE about a year of cruising time.
On 19 August 2024, JUICE swung past the Moon. About 36 hours later, on 20 August 2024, it swung past Earth at a distance of about 6,800 km. This double-flyby had never been attempted before — and ESA’s flight team did it so precisely they used only a tiny fraction of the propellant set aside for the manoeuvre. The leftover fuel may be used later to extend JUICE’s science mission at Jupiter.
Stage 2: Venus flyby — 31 August 2025 ✅
On 31 August 2025, JUICE flew past Venus for its second gravity assist. The pass nearly didn’t happen — in July 2025, JUICE briefly lost contact with Earth because of a software timing glitch. ESA mission controllers tracked down the cause and restored communications in time for the Venus flyby. Crisis averted!
Stage 3: Earth flybys — September 2026 and January 2029
JUICE returns to Earth twice more for gravity boosts — in September 2026 and January 2029. After the January 2029 flyby, JUICE will leave Earth for the last time and head straight for Jupiter.
Stage 4: Jupiter arrival — July 2031
After eight years of looping through the inner solar system, JUICE is scheduled to arrive at Jupiter in July 2031. From there, it will spend years touring Jupiter’s moons before — if successful — settling into orbit around Ganymede in late 2034.
Stage 5: 21 Callisto flybys, plus Europa visits — 2031–2034
Before entering Ganymede orbit, JUICE is planned to make about 21 close flybys of Callisto, plus visits to Europa, plus general observations of Jupiter from above. By the time JUICE reaches Ganymede orbit, it will already have done more close-up science of Callisto than any spacecraft in history.
Stage 6: Ganymede orbit — December 2034 (planned)
If everything goes well, in December 2034 JUICE is planned to enter orbit around Ganymede — the biggest moon in the solar system. If successful, JUICE will become the first spacecraft in history to orbit a moon other than Earth’s Moon. The science mission would then run until about 2035.
JUICE’s journey is eight years long. If you are 10 when you read this in 2026, you will be in your late teens when JUICE arrives at Jupiter in 2031 — maybe leaving school or starting university. By the time JUICE enters Ganymede orbit in 2034, you might be in your twenties. The science from this mission belongs to a generation that is in school right now.
JUICE’s 10 science instruments
JUICE carries 10 science instruments — the most ever sent on a single mission to Jupiter. Each one is built to answer a different question about the icy moons. Some of the most important are:
- RIME — ice-penetrating radar to look down through the icy crusts of Ganymede, Europa and Callisto, possibly all the way to their hidden oceans
- J-MAG — a magnetometer to measure magnetic fields, especially Ganymede’s (the only moon with its own)
- GALA — a laser altimeter that bounces laser pulses off the moons’ surfaces to measure their shapes
- JANUS — the main camera, named after the Roman god with two faces (one looking past, one looking forward)
- MAJIS — an infrared spectrometer to study the chemistry of moon surfaces
- UVS — an ultraviolet spectrograph to look for plumes and study moons’ thin atmospheres
- 3GM — uses radio signals to measure the gravity of Ganymede and other moons
- PEP — measures charged particles around Jupiter and its moons
- SWI — sub-millimetre wave instrument for studying Jupiter’s atmosphere
- RPWI — listens to radio waves around Jupiter, including “space lightning” in the magnetosphere
Cool extras about JUICE
Built to survive the cold and the radiation
Jupiter’s environment is brutally cold and full of dangerous radiation. JUICE is wrapped in thick, gold-coloured multilayer insulation — the shiny material you can see in most JUICE photos. The insulation keeps the spacecraft’s heaters from working too hard, and helps protect its instruments from radiation damage.
A child’s artwork went to space
Before JUICE launched, ESA invited children from around the world to create JUICE-inspired artwork. The winning entry — painted by eight-year-old Yaryna from Ukraine — was painted onto the side of the Ariane 5 rocket that launched JUICE on 14 April 2023. The rocket has long since fallen back to Earth as planned, but Yaryna’s artwork helped send JUICE on its way.
JUICE was launched on an Ariane 5 rocket — the same family of rockets that has launched many of Europe’s most important space missions. JUICE’s launch was the second-to-last Ariane 5 flight before the rocket family retired in July 2023. So JUICE is one of the very last spacecraft Ariane 5 ever launched.
Talking to home from Jupiter
By the time JUICE arrives at Jupiter, radio signals between Earth and the spacecraft will take roughly 45 minutes to an hour to travel each way. That means JUICE has to do almost everything by itself — there is no time for mission controllers to react quickly to anything that goes wrong.
JUICE, Juno, and Europa Clipper — the three modern Jupiter missions
JUICE is one of three big modern Jupiter missions. Each has a different job:
- Juno (NASA, launched 2011) — studied Jupiter’s interior and weather from polar orbit. Read more →
- Europa Clipper (NASA, launched 2024) — cruising now; will focus on Europa’s habitability with 49 flybys. Read more →
- JUICE (ESA, launched 2023) — cruising now; will focus on Ganymede plus visits to Europa and Callisto.
Together, these three missions are giving scientists the best look at Jupiter’s system since the Galileo mission (1995–2003). Never before has so much been studied at Jupiter at once.
JUICE is a great example of international collaboration. The mission is led by ESA but includes contributions from NASA, JAXA (Japan), the Israel Space Agency, and over 80 companies across Europe. Ask students: why might space agencies work together on big missions instead of going alone? (Cost, expertise, sharing risk, sharing results, building international goodwill.) This is also a chance to talk about how science transcends borders.
Frequently asked questions about JUICE
What is JUICE?
JUICE is the European Space Agency’s spacecraft heading to Jupiter’s icy moons. It launched on 14 April 2023 and is scheduled to arrive at Jupiter in July 2031. JUICE will study Ganymede, Callisto, and Europa — three of Jupiter’s big Galilean moons — and is planned to eventually orbit Ganymede.
What does JUICE stand for?
JUICE stands for JUpiter ICy moons Explorer. It is a slightly forced acronym, but the name stuck because it is catchy and easy to remember.
When did JUICE launch?
JUICE launched on 14 April 2023 from ESA’s spaceport in Kourou, French Guiana, on an Ariane 5 rocket. It was the second-to-last Ariane 5 launch before the rocket family retired.
When will JUICE arrive at Jupiter?
JUICE is scheduled to arrive at Jupiter in July 2031, after an eight-year journey using gravity assists from the Moon, Earth, Venus, and Earth again.
What moons will JUICE study?
JUICE will study three of Jupiter’s four big Galilean moons: Ganymede, Callisto, and Europa. The fourth Galilean moon, Io, is too radiation-blasted for JUICE to safely visit closely.
Will JUICE land on Ganymede?
No. JUICE will orbit Ganymede, not land on it. The plan is for JUICE to become the first spacecraft ever to orbit a moon other than Earth’s Moon — but it stays above the surface.
Is JUICE looking for aliens?
No. JUICE is a habitability mission — it studies whether Jupiter’s icy moons have the right conditions for life (water, energy, chemistry). It cannot detect actual living things. A different, future mission would be needed for that.
What was the Lunar-Earth flyby?
On 19–20 August 2024, JUICE made a world-first manoeuvre — flying past the Moon, then past Earth, within just 36 hours. No spacecraft had ever done that before. Picking up speed from both helped JUICE save about a year of cruising time.
Did JUICE really lose contact with Earth?
Yes — briefly. In July 2025, a small software timing glitch caused JUICE to stop sending status updates to Earth. ESA engineers worked quickly to fix the problem and restored communications in time for the Venus flyby on 31 August 2025.
Why does JUICE take so long to get to Jupiter?
Because it is very heavy — too heavy to be flown directly using rocket fuel alone. JUICE uses four gravity assists (Moon-Earth, Venus, Earth, Earth) to gain enough speed to reach Jupiter. Each gravity assist saves huge amounts of fuel but adds time.
Quick recap
- JUICE = JUpiter ICy moons Explorer, from the European Space Agency
- Launched 14 April 2023 on an Ariane 5 rocket
- Path: Lunar-Earth flyby (Aug 2024 ✅) → Venus (Aug 2025 ✅) → Earth (2026) → Earth (2029) → Jupiter (July 2031)
- Will study three icy moons: Ganymede, Callisto, and Europa
- If successful, will become the first spacecraft ever to orbit a moon other than Earth’s Moon (Ganymede, December 2034)
- Mission goal: study moon habitability — not search for aliens directly
- Did the first-ever Lunar-Earth combined flyby in August 2024
Learn more about the moons JUICE will visit — Ganymede, Callisto, Europa — or compare JUICE with Juno and Europa Clipper. Or head back to the main Jupiter pillar.