Juice mission: discovering the icy moons of 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. 

 

 

Sources 

[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.