With all this fuss about SpaceX Starship we forgot to tell about another, and perhaps even more interesting, space launch this month. It’s about sending the JUICE (Jupiter Icy Moons Explorer) mission to, yes, Jupiter. Let’s fix it.

The mission of JUICE and the Ukrainian footprint

The Jupiter Icy Moons Explorer (JUICE) is a long-term program of the European Space Agency (ESA). The mission was approved in 2012, and in 2015 Airbus Defense and Space began the development and construction of the JUICE spacecraft.

It is interesting that Ukrainian plane An-124-100 of Antonov Airlines delivered spacecraft from the Airbus plant in Toulouse (France) to the Kourou Cosmodrome (French Guiana). And this is not the only Ukrainian trace in the story of JUICE.


The main fairing of the Ariane 5 ECA launch vehicle, which launched the satellite into space, was decorated with a child’s drawing, which won the competition introduced by ESA in 2021. The author of the drawing is Ukrainian Yaryna Zakaliuzhna, the girl was 8 years old at the time.

JUICE  – a mission to Jupiter that will arrive in 8 years

Maneuvers in space

The JUICE mission launched from Kourou Cosmodrome on April 14, 2023. Ariane 5 ECA (Evolution Cryotechnique type A – the fourth and current generation of Ariane 5 rockets, which has been flying since 2005) performed normally, the device separated from the launch vehicle and opened the solar panels. But this is only the beginning of JUICE’s Great Journey through the Solar System. The fact is that JUICE went to Jupiter on a very energy-efficient, but very long trajectory, which involves numerous gravitational maneuvers.

JUICE maneuvers:
August 2024 – gravitational maneuver near the Moon and the Earth;
August 31, 2025 – gravitational maneuver near Venus;
September 29, 2026 – the first gravitational maneuver near the Earth;
January 18, 2029 – the second gravitational maneuver near the Earth;
October 15, 2029 – flyby of asteroid 223 Rosa;
July 2031 – arrival in the orbit of Jupiter;
December 2034 – arrival in orbit of Ganymede.

And this is only a fraction of JUICE’s maneuvers. In the Jupiter system, the device will perform more than 25 gravitational maneuvers around the satellites of the giant planet, including several flybys of Europa.

JUICE  – a mission to Jupiter that will arrive in 8 years

At the end of 2035, JUICE is scheduled to leave Ganymede orbit and collide with its surface. Of course, for scientific purposes.

Interestingly, a similar NASA Europa Clipper mission, due to launch in 2024, will arrive at Jupiter earlier than JUICE in 2030.

JUICE device

Due to a large amount of maneuvering, the basis of the JUICE mass is the fuel itself. With a dry weight of the device of 2,420 kg (including the adapter for placement under the Ariane 5 ECA fairing), the fuel weight is 3,650 kg! The JUICE engine uses a two-component hypergolic (components of which are self-igniting) fuel mixture of monomethylhydrazine and a mixture of nitrogen oxides. A thrust of 425 N is enough for orbital maneuvers.

JUICE  – a mission to Jupiter that will arrive in 8 years


Another problem of working at such a distance from the Sun is the power supply. There are now difficulties with RITEGs, which were used by Pioneer 10/11, Voyager 1/2, Cassini, New Horizons, Mars rovers Curiosity, and Perseverance, so scientists rely on solar panels. But in Jupiter’s orbit, sunlight provides 25 times less energy, so the device needs VERY large solar panels.

And JUICE has them really big. The device, which under the rocket fairing measures only 4.09 × 2.86 × 4.35 m, after opening the solar panels significantly increases to 16.8 × 27.1 × 13.7 m. JUICE solar panels have an unusual cross shape, consist of identical blocks of 2.5 × 3.5 m (five on each side), and have a total area of 85 m2. This is a record for the devices that went into deep space.

JUICE  – a mission to Jupiter that will arrive in 8 years


But even such a large area of panels will provide a total power of only 850 W in Jupiter’s orbit. As the designers of the device themselves joke, if in Earth’s orbit, the panels are enough to power the houses on an entire street, then in Jupiter’s orbit, it is barely enough for a microwave oven.

In addition to solar panels, JUICE has five powerful batteries that power the device when it is in the shadow of Jupiter, and such periods can last up to 5 hours.

Scientific data is stored on a built-in storage device with a capacity of 1.25 TB. This should be enough for several days of observation. 2.5 m narrow and wide X- and K-band antennas are responsible for transmitting information to Earth. Transmission speeds over long distances are only 2 Gb per day using NASA’s Deep Space Network’s giant antennas on Earth. The JUICE control center is located in Darmstadt, Germany.

Scientific tasks

JUICE’s mission, as you can see from its name Jupiter Icy Moons Explorer, is to study the icy moons of Jupiter.

More than others, scientists are interested in Ganymede, especially its mysterious magnetic field, complex crust, ice, and subglacial oceans. In addition, JUICE will search Ganymede for biosignatures.

JUICE  – a mission to Jupiter that will arrive in 8 years

Europa is no less interesting. Here, scientists are going to “see” the subglacial and potentially habitable ocean and study the mysterious cracks on the surface of the satellite.

In Callisto, as the most distant and stable of the large moons of Jupiter, scientists are interested in the presence of an ocean under the surface, the study of the history of the formation of the satellite, the magnetic field, and the ionosphere.

JUICE  – a mission to Jupiter that will arrive in 8 years

In addition, JUICE plans to study other moons of Jupiter, as of 2023, 95 of them have already been found, and the entire system in general.

The scientific load of JUICE is relatively small compared to the fuel mass – only 104 kg, but these are modern and progressive instruments. Among them: a JANUS camera with a field of view of 1.3°, equipped with 13 light filters; MAJIS multispectral spectrometer; UVS ultraviolet imaging spectrograph; SWI sub-millimeter wave spectrometer; J-MAG magnetometer; GALA altimeter for studying the tidal deformation of Ganymede; RIME under-ice radar sounder; PEP particle environment package; RPWI, a tool for studying radio waves; a 3GM tool for studying the gravitational field; PRIDE Doppler interferometer.

JUICE  – a mission to Jupiter that will arrive in 8 years

Scientists from the Netherlands, Italy, Sweden, Great Britain, Germany, and the USA participated in the development of tools for JUICE. That is, it is a truly international project.

Good luck, JUICE!

Let’s hope that during JUICE’s long journey through the solar system, nothing will happen to the device, and in 8 years we will receive new high-quality photos of Jupiter and its “family”. And, of course, new scientific data will help scientists understand the construction of gas giant systems, the nuances of the evolution of star systems, and possibly the origin of life.

We are setting reminders for July 2031 on smartphones!