The surface of Jupiter's icy moon Europa

Jupiter’s moon Europa has an icy crust, but an analysis of spacecraft data confirms that plumes of water vapour issue from its surface. Credit: NASA/JPL-Caltech/SETI Institute

Planetary science

A geyser spurts from one of Jupiter’s icy moons

Galileo spacecraft bolsters evidence for watery plumes on Europa.

Close-up observations of Jupiter’s moon Europa confirm that a plume, probably of water vapour, rises from its surface.

Scientists had already garnered hints of such a feature from the Hubble Space Telescope, which orbits Earth. But Xianzhe Jia at the University of Michigan in Ann Arbor and his colleagues analysed observations made by the Galileo spacecraft as it swooped past Europa.

The team compared Galileo data with computer simulations of the magnetic field and charged particles around the moon. The results consistently indicate that a plume emanates from a spot on Europa’s surface close to the location suggested by Hubble.

The presence of such a plume on Europa — like those of Saturn’s moon Enceladus — implies that the moon’s icy crust hides a vast ocean. The findings will inform the planning of missions that aim to return to these moons in the 2020s and early 2030s.