Spacecraft: ESA/ATG medialab; Jupiter: NASA/ESA/J. Nichols (University of Leicester); Ganymede: NASA/JPL; Io: NASA/JPL/University of Arizona; Callisto and Europa: NASA/JPL/DLR
Exploring Jupiter and its icy moons
The Jupiter Icy Moons Explorer (JUICE) is designed to systematically explore the planet Jupiter and its moons. The spacecraft will study the structure, dynamics and composition of Jupiter's atmosphere and the magnetic fields of Jupiter and Ganymede. Ganymede is not only the giant planet’s largest moon, but also the only natural satellite in the Solar System with its own magnetic field. Like Jupiter’s moons Europa and Callisto, it has an icy surface beneath which oceans of liquid water are suspected to exist. Another key task of the JUICE mission will be to test this assumption, as the presence of such oceans would allow for the possibility of the emergence of extraterrestrial life.
Investigations of Europa and Callisto will complete the picture of the Galilean moons. Two flybys of Jupiter’s moon Europa are planned. During these flights, the surface composition will be determined and its interior indirectly studied.
JUICE will be the first mission to enter orbit around another planet’s moon. As Jupiter is the archetype of a gas giant, the researchers hope that the knowledge gained during the JUICE mission will be at least partially applicable to similar exoplanet systems. The spacecraft was launched on an Ariane 5 launcher on 14 April 2023 from the European spaceport in Kourou, French Guiana, and will reach Jupiter after a travel time of approximately 7.5 years.
A seven-year journey to the Jupiter system
Once in space, JUICE will perform four flyby manoeuvres. The spacecraft will use the gravity of Venus and Earth to gain momentum for its approximately 7.5-year journey to Jupiter. After entering orbit around Jupiter, the spacecraft will explore the Jupiter system for three years. During this time, it will use the gravity of Callisto and Ganymede to change its trajectory. It will also increase its orbital inclination in the Jupiter system to almost 30 degrees, allowing it to observe Jupiter’s poles.
Frequent Callisto flybys will enable unique remote sensing of the moon and in situ measurements of its surroundings. The mission will culminate in a nine-month orbital phase around Ganymede, during which the spacecraft will study the moon and its surroundings in detail, before ultimately executing a targeted impact into Ganymede.
Scientific instruments with German participation
Jupiter and its four Galilean moons Io, Europa, Ganymede and Callisto
Galileo Galilei discovered Jupiter's four moons Io, Europa, Ganymede and Callisto in 1610 with the help of a telescope he had made himself. These Galilean moons are not only the largest moons of Jupiter, but are also among the largest in the solar system. While Io is characterised by volcanism, water oceans are suspected beneath the surfaces of the three icy moons Europa, Ganymede and Callisto. The positions in the figure are illustrative.
The JUICE spacecraft carries ten instruments that will be used to carry out scientific investigations. The GALA, SWI, PEP, J-MAG, RIME and 3GM instruments and the JANUS camera system were developed and implemented with German input.
The Ganymede Laser Altimeter (GALA) will be used to gauge the distance between JUICE and Ganymede by measuring the transit time of laser pulses, which are emitted by the instrument, backscattered on the moon’s surface and detected by the instrument’s receiver telescope. These data will allow researchers to determine the moon’s topography and tidal deformation, and how it changes over time. From this information, they will be able to determine the existence of an ocean of water beneath the moon’s icy crust.
The Submillimetre Wave Instrument (SWI) is designed to study the middle layers of Jupiter’s atmosphere and the ultra-thin atmospheres and surfaces of the Galilean moons. Here, the focus is on determining the temperature structure, dynamics and composition of the various layers of Jupiter’s atmosphere, the way in which they interact with each other, and Jupiter's internal structure.
The ‘Jovis, Amorum ac Natorum Undique Scrutator’ (JANUS) camera system will be used to study global, regional and local morphology and processes on the moons. The physical and dynamic properties of the small moons and rings will also be determined. Images acquired using JANUS will be used to record the entire Jupiter system, including Jupiter’s atmosphere.
The Particle Environment Package (PEP) spectrometer will be used to measure neutral and charged particles in the vicinity of Jupiter and its moons. PEP consists of six different particle detectors designed to detect electrons, ions and uncharged particles in a range from approximately one electron volt to 10 kiloelectron volts. The PEP sensors are mounted at different positions on the spacecraft (its nadir and zenith points).
The Jupiter Magnetometer (J-MAG) will be used to study the magnetosphere of Jupiter and its moons. A clear distinction between the magnetic fields is essential for the correct interpretation of the magnetic field data. The measurement of induced magnetic fields should assist the detection of subsurface oceans on the icy moons.
The Radar for Icy Moons Exploration (RIME) instrument will be used to analyse the subsoil of the icy moons and identify warm spots and structures within their ice sheets. RIME will also be used to search for transitions between water and ice. Its signal can penetrate to a depth of approximately nine kilometres below the surface and was designed to provide new scientific insights into the geology and geophysics of the frozen moons.
The Gravity & Geophysics of Jupiter and Galilean Moons (3GM) radio sounder consists of two units - a Ka-band transponder and an ultra-stable oscillator - which are integrated into the spacecraft’s telemetry, tracking and command subsystem. 3GM will primarily be used to measure the gravitational fields of Jupiter’s moons. Jupiter’s atmosphere and the plasma spheres of the Jupiter moons will also be examined by conducting occultation measurements. The 3GM measurements can also be used to increase the accuracy of JUICE’s orbit parameters, thus improving the quality of data from the spacecraft’s other instruments.
JUCIE space probe with payload consisting of ten scientific instruments.
JUICE will carry the most powerful remote sensing, geophysical and in-situ payloads ever flown into the outer solar system.
International collaboration on the first major Cosmic Vision mission
The JUICE mission is a collaboration between the European Space Agency (ESA), NASA, and the Japanese space agency, JAXA. This is the first major mission of the ESA Cosmic Vision 2015-2025 programme. An international consortium led by Airbus Defence and Space developed and built the JUICE satellite.
The GALA and SWI instruments were developed and built under German leadership. German institutions are also involved in the PEP, J-MAG, RIME and 3GM instruments and the JANUS camera system. This German contributions are financed by the German Space Agency at DLR with funding from the Federal Ministry for Economic Affairs and Climate Action (BMWK).
Mission data
JUICE - Jupiter Icy Moons Explorer
Mission type
L1 Mission, ESA
Mission focus
Formation of habitable worlds around gas giants. The Jupiter system as an archetype for gas giants.
Start date
14 April 2023
Launch site
Europe’s Spaceport (French Guiana)
Launch vehicle
Ariane 5 CEA
Mass at launch
6100 kilograms, of which 2450 kilograms dry mass (satellite including instruments) and 3650 kilograms fuel
Mission duration
7.6 years interplanetary flight time and 3.5 years in the Jupiter system
Satellite
Three-axis stabilisation Two solar panels with five elements each (total area 85 square metres) Electrical power: ~900 watts (at the end of the mission) Energy storage system: lithium-ion battery Fixed high gain antenna: 2.5 metres
Telemetry
X- and Ka-bands Downlink: more than 1.4 gigabits per day
Orbit
2031: entry into orbit around Jupiter Jupiter tour: Transfer to Callisto (11 months) Europa phase: two Europa and three Callisto flybys (one month) High-latitude Jupiter phase: nine Callisto flybys (nine months) Transfer to Ganymede (11 months) 2034: entry into orbit around Ganymede Ganymede tour: Elliptical and circular orbits at high altitude (5000 kilometres) (five months) Circular orbit at low altitude (500 kilometres) (four months)
