Juice mission: discovering the icy moons of Jupiter

ESA's Jupiter Icy Moons Explorer (Juice) lifted off on an Ariane 5 rocket on 14 April 2023. This successful launch marks the beginning of an ambitious journey to discover the secrets of the ocean worlds around the giant planet Jupiter. 

Thanks to the legacy of previous missions to Jupiter, notably the Galileo spacecraft, we know that three of the planet's largest moons - Europa, Ganymede and Callisto - are covered in ice holding quantities of water buried under their surfaces in volumes far greater than in Earth’s oceans. [1]  The European Space Agency (ESA)’s Jupiter Icy Moons Explorer, Juice, will make detailed observations of the giant gas planet and its three large ocean-bearing moons with a suite of ten unique science instruments, one experiment and one radiation monitor. [1] 


ESA's Jupiter Icy Moons Explorer (Juice) lifted off on an Ariane 5 rocket on 14 April 2023.  In its upper stage, the Ariane 5 rocket carries liquid oxygen and liquid hydrogen: these fuels power the last engine to come into action, the one that places the satellite in orbit. [2] For the propellants to remain liquid, they must be kept at a very cold temperature at all times: -253°C for hydrogen, and between -193°C and -183°C for oxygen. As soon as they warm up, the propellants revert to a gaseous state and are therefore lost. To compensate for these losses, two giant "cryogenic" filling arms remain attached to Ariane 5 until the very last seconds before lift-off. [2] 


Following launch, Juice will embark on an eight-year journey to Jupiter, arriving in July 2031. 




[1] The Juice mission media kit. https://www.esa.int/Newsroom/Press_Releases/ESA_s_Juice_lifts_off_on_quest_to_discover_secrets_of_Jupiter_s_icy_moons  

[2] CNES. Des bras cryotechniques pour décoller avec le plein  https://spacegate.cnes.fr/fr/quezako-des-bras-cryotechniques-pour-decoller-avec-le-plein  

[3] https://www.esa.int/Enabling_Support/Space_Transportation/Launch_vehicles/Cryogenic_main_stage_EPC  

Image source: Credit ESA - S. Corvaja. Flight VA260 is the final Ariane 5 flight to carry an ESA mission to space.