En route to Jupiter, the JUICE mission (ESA) observed the interstellar comet 3I/ATLAS using five of its instruments, including MAJIS, a visible-infrared imaging spectrometer to which LIRA contributed.
Observed in November 2025, shortly after its closest approach to the Sun, the comet revealed intense activity : the sublimation of ice buried beneath the surface, released by solar heating. MAJIS detected emissions of carbon dioxide and water vapour, with an estimated outgassing rate of 2 tonnes per second (equivalent to 70 Olympic-sized swimming pools per day !).
Comet 3I/ATLAS was identified in July 2025 and is only the third known interstellar comet. A rare visitor, arriving from another star system, bearing valuable clues about the composition of materials formed around other stars. Combined with observations from the JWST and large ground-based telescopes, these data thus open a unique window onto the history of our Universe.
