Jupiter Icy Moons Explorer
Artist's impression of the Juice spacecraft
NamesJuice, JUICE
Mission typePlanetary science
COSPAR ID2023-053A Edit this at Wikidata
SATCAT no.56176Edit this on Wikidata
Mission durationCruise phase: 8 years
Science phase: 3.5 years
Elapsed: 9 months and 9 days
Spacecraft properties
ManufacturerAirbus Defence and Space
Launch mass6,070 kg (13,380 lb)[1]
Dry mass2,420 kg (5,340 lb)[1]
Dimensions16.8 x 27.1 x 13.7 meters[1]
Power850 watts from a solar panel ~85 m2 (910 sq ft)[1]
Start of mission
Launch date14 April 2023 12:14:36 UTC [2]
RocketAriane 5 ECA
Launch siteCentre Spatial Guyanais, ELA-3
Flyby of Moon
Closest approach19 August 2024
Flyby of Earth
Closest approach20 August 2024
Flyby of Venus
Closest approach31 August 2025
Flyby of Earth
Closest approach29 September 2026
Flyby of Earth
Closest approach18 January 2029
Flyby of 223 Rosa
Closest approach15 October 2029 (proposed)
Jupiter orbiter
Orbital insertionJuly 2031 (planned)
Orbital departureDecember 2034 (planned)
Ganymede orbiter
Orbital insertionDecember 2034 (planned)
Orbital parameters
Periapsis altitude500 km (310 mi)
Apoapsis altitude500 km (310 mi)
Juice mission logo
Juice mission insignia
← Euclid

The Jupiter Icy Moons Explorer (Juice, formerly JUICE[3]) is an interplanetary spacecraft that was launched on 14 April 2023 from Guiana Space Centre in the French Guiana by the European Space Agency (ESA) with Airbus Defence and Space as the main contractor.[4][5] The mission is planned to study Ganymede, Callisto, and Europa, three of Jupiter's Galilean moons. They are thought to have significant bodies of liquid water beneath their icy surfaces which would make them potentially habitable environments.[6][7]

The spacecraft was launched on 14 April 2023 at 12:14:36 UTC[2] and is expected to reach Jupiter in July 2031 after four gravity assists and eight years of travel.[8][9] In December 2034, the spacecraft will enter orbit around Ganymede for its close-up science mission.[8] Its period of operations will overlap with NASA's Europa Clipper mission, launching in 2024.


The mission, started as a reformulation of the Jupiter Ganymede Orbiter proposal, which was to be ESA's component of the cancelled Europa Jupiter System Mission – Laplace (EJSM-Laplace).[10] It became a candidate for the first L-class mission (L1) of the ESA Cosmic Vision Programme, and its selection was announced on 2 May 2012.[11]

In April 2012, JUICE was recommended over the proposed Advanced Telescope for High Energy Astrophysics (ATHENA) X-ray telescope and a gravitational wave observatory (New Gravitational wave Observatory (NGO)).[12][13]

In July 2015, Airbus Defence and Space was selected as the prime contractor to design and build the probe, to be assembled in Toulouse, France.[14]

By 2023, the mission was estimated to cost ESA 1.5 billion euros ($1.6 billion).[15]


The main spacecraft design drivers are related to the large distance to the Sun, the use of solar power, and Jupiter's harsh radiation environment. The orbit insertions at Jupiter and Ganymede and the large number of flyby manoeuvres (more than 25 gravity assists, and two Europa flybys) require the spacecraft to carry about 3,000 kg (6,600 lb) of chemical propellant.[16]

Juice has a fixed 2.5 meter diameter high-gain antenna and a steerable medium-gain antenna, both X- and K-band will be used. Downlink rates of 2 Gb/day are possible with ground-based Deep Space Antennas. On-board data storage capability is 1.25 Tb.[1]

The Juice main engine is a hypergolic bi-propellant (mono-methyl hydrazine and mixed oxides of nitrogen) 425 N thruster. A 100 kg multilayer insulation provides thermal control. The spacecraft is 3-axis stabilized using momentum wheels. Radiation shielding is used to protect onboard electronics from the Jovian environment.[1]

The Juice science payload has a mass of 280 kg and includes the JANUS camera system, the MAJIS visible and infrared imaging spectrometer, the UVS ultraviolet imaging spectrograph, RIME radar sounder, GALA laser altimeter, SWI submillimetre wave instrument, J-MAG magnetometer, PEP particle and plasma package, RPWI radio and plasma wave investigation, 3GM radio science package, the PRIDE radio science instrument, and the RADEM radiation monitor. A 10.6-meter deployable boom will hold J-MAG and RPWI, a 16-meter-long deployable antenna will be used for RIME. Four 3-meter booms carry parts of the RPWI instrument. The other instruments are mounted on the spacecraft body, or for 3GM, within the spacecraft bus.[1]



Ariane 5 launch of the ESA Juice spacecraft

Juice was launched into space on 14 April 2023 from the Guiana Space Centre on an Ariane 5 rocket. This was the final launch of an ESA science mission using the Ariane 5 vehicle,[17] and was the second to last launch of the rocket overall.[18]

The launch was originally scheduled for 13 April 2023, but due to poor weather the launch was postponed.[19] The next day a second launch attempt succeeded, with liftoff occurring at 12:14:36 UTC. After the spacecraft separated from the rocket, it established a successful radio signal connection with the ground at 13:04 UTC. Juice's solar arrays were deployed about half an hour later, prompting ESA to deem the launch a success.[17]


Following the launch, there will be multiple planned gravity assists to put Juice on a trajectory to Jupiter: a flyby of the Earth–Moon system in August 2024, Venus in August 2025, second flyby of Earth in September 2026, and a third and final flyby of Earth in January 2029.[8]

Juice will pass through the asteroid belt twice. A flyby of the asteroid 223 Rosa has been proposed, and could occur in October 2029.[20][21]

Gravity assists include:[22]

Trajectories of Juice
Around the Sun
Around Jupiter
Around Ganymede
  Sun ·   Earth ·   Juice ·   Venus ·   223 Rosa ·   Jupiter ·   Ganymede ·   Callisto  ·   Europa

Arrival at the Jovian system

When it arrives in Jupiter's system in July 2031, Juice will first perform a flyby of Ganymede in preparation for Jupiter orbital insertion about 7.5 hours later. The first orbit will be elongated, with subsequent orbits gradually lowered over time, resulting in a circular orbit around Jupiter.[8]

The first Europa flyby will take place in July 2032. Juice will enter a high inclination orbit to allow exploration of Jupiter's polar regions and to study Jupiter's magnetosphere.[8]

Orbital insertion on Ganymede

In December 2034, Juice will enter an elliptical orbit around Ganymede. The first orbit will be at a distance of 5,000 km (3,100 mi). In 2035, JUICE will enter a circular orbit 500 km (310 mi) above the surface of Ganymede.[8] Juice will study Ganymede's composition and magnetosphere among other things.

Planned deorbit on Ganymede

When the spacecraft consumes its remaining propellant, Juice is planned to be deorbited and impact Ganymede at the end of 2035.[8]

Science objectives

Ganymede view by the Galileo spacecraft
Section of Europa's icy surface

The JUICE orbiter will perform detailed investigations on Ganymede and evaluate its potential to support life. Investigations of Europa and Callisto will complete a comparative picture of these Galilean moons.[23] The three moons are thought to harbour internal liquid water oceans, and so are central to understanding the habitability of icy worlds.

The main science objectives for Ganymede, and to a lesser extent for Callisto, are:[23]

For Europa, the focus is on the chemistry essential to life, including organic molecules, and on understanding the formation of surface features and the composition of the non-water-ice material. Furthermore, JUICE will provide the first subsurface sounding of the moon, including the first determination of the minimal thickness of the icy crust over the most recently volcanically active regions.

More distant spatially resolved observations will also be carried out for several minor irregular satellites and the volcanically active moon Io.

Science instruments

JUICE instruments

On 21 February 2013, after a competition, 11 science instruments were selected by ESA, which were developed by science and engineering teams from all over Europe, with participation from the US.[24][25][26][27] Japan also contributed several components for SWI, RPWI, GALA, PEP, JANUS and J-MAG instruments, and will facilitate testing.[28][29][30]

Jovis, Amorum ac Natorum Undique Scrutator (JANUS)

The name is Latin for "comprehensive observation of Jupiter, his love affairs and descendants."[31] A camera system to image Ganymede and interesting parts of the surface of Callisto at better than 400 m/pixel (resolution limited by mission data volume). Selected targets will be investigated in high-resolution with a spatial resolution from 25 m/pixel down to 2.4 m/pixel with a 1.3° field of view. The camera system has 13 panchromatic, broad and narrow-band filters in the 0.36 µm to 1.1 µm range, and provides stereo imaging capabilities. JANUS will also allow relating spectral, laser and radar measurements to geomorphology and thus will provide the overall geological context.

Moons and Jupiter Imaging Spectrometer (MAJIS)

A visible and infrared imaging spectrograph operating from 400 nm to 5.70 µm, with spectral resolution of 3–7 nm, that will observe tropospheric cloud features and minor gas species on Jupiter and will investigate the composition of ices and minerals on the surfaces of the icy moons. The spatial resolution will be down to 75 m (246 ft) on Ganymede and about 100 km (62 mi) on Jupiter.

UV Imaging Spectrograph (UVS)

An imaging spectrograph operating in the wavelength range 55–210 nm with spectral resolution of <0.6 nm that will characterise exospheres and aurorae of the icy moons, including plume searches on Europa, and study the Jovian upper atmosphere and aurorae. Resolution up to 500 m (1,600 ft) observing Ganymede and up to 250 km (160 mi) observing Jupiter.

Sub-millimeter Wave Instrument (SWI)

A spectrometer using a 30 cm (12 in) antenna and working in 1080–1275 GHz and 530–601 GHz with spectral resolving power of ~107 that will study Jupiter's stratosphere and troposphere, and the exospheres and surfaces of the icy moons.

Ganymede Laser Altimeter (GALA)

A laser altimeter with a 20 m (66 ft) spot size and 10 cm (3.9 in) vertical resolution at 200 km (120 mi) intended for studying topography of icy moons and tidal deformations of Ganymede.

Radar for Icy Moons Exploration (RIME)
The RIME antenna in stowed configuration. A "selfie" photograph, shortly after launch by the Juice monitoring camera 2 (JMC2), with Earth in the background

An ice-penetrating radar working at frequency of 9 MHz (1 and 3 MHz bandwidth) emitted by a 16 m (52 ft) antenna; will be used to study the subsurface structure of Jovian moons down to 9 km (5.6 mi) depth with vertical resolution up to 30 m (98 ft) in ice.

During post-launch commissioning of the spacecraft, the RIME antenna failed to properly deploy from its mounting bracket.[32] After several weeks of attempts to free the instrument, it was successfully deployed on 12 May.[33]

JUICE-Magnetometer (J-MAG)
The scalar sub-instrument (MAGSCA), an optical magnetometer with low absolute error, is part of J-MAG

JUICE will study the subsurface oceans of the icy moons and the interaction of Jovian magnetic field with the magnetic field of Ganymede using a sensitive magnetometer.

Particle Environment Package (PEP)

A suite of six sensors to study the magnetosphere of Jupiter and its interactions with the Jovian moons. PEP will measure positive and negative ions, electrons, exospheric neutral gas, thermal plasma and energetic neutral atoms present in all domains of the Jupiter system from 1 meV to 1 MeV energy.

Radio and Plasma Wave Investigation (RPWI)

RPWI will characterise the plasma environment and radio emissions around the spacecraft, it is composed of four experiments: GANDALF, MIME, FRODO and JENRAGE. RPWI will use four Langmuir probes, each one mounted at the end of its own dedicated boom, and sensitive up to 1.6 MHz to characterize plasma and receivers in the frequency range 80 kHz to 45 MHz to measure radio emissions. This scientific instrument is somewhat notable for using Sonic the Hedgehog as part of its logo.[34][35]

Gravity and Geophysics of Jupiter and Galilean Moons (3GM)

3GM is a radio science package comprising a Ka transponder and an ultrastable oscillator.[36] 3GM will be used to study the gravity field – up to degree 10 – at Ganymede and the extent of internal oceans on the icy moons, and to investigate the structure of the neutral atmospheres and ionospheres of Jupiter (0.1 – 800 mbar) and its moons.

Planetary Radio Interferometer and Doppler Experiment (PRIDE)

The experiment will generate specific signals transmitted by JUICE's antenna and received by very-long-baseline interferometry to perform precision measurements of the gravity fields of Jupiter and its icy moons.

See also


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