NASA’s Juno probe flew just 1,500 kilometers above the surface of Io, one of Jupiter’s moons, on December 30 and provided images of this moon where active and turbulent processes are taking place. The photographs taken by “Juno” were the most detailed photographs of the last 22 years.

Io is the most volcanic world in the Solar System, its eruptions are several times more powerful than those occurring on Earth. The intensity of volcanic activity on Io is mainly due to the gravitational influence of Jupiter, resulting from the movement of a satellite in the Jupiter system. Other giant moons (Ganymede, Europa and Callisto) amplify this effect, causing strong tidal heating on Io.

Io’s 42-day geostationary orbit around Jupiter produces significant internal heat. In this context, scientists hypothesize that large magmatic oceans may exist beneath the moon’s hard rocky crust.

An important result of the work was the discovery of Loki Patera, the largest volcanic crater and most energetic hotspot on Io, containing a lake or lava sea.

The Juno mission has made close flybys of Jupiter’s three giant moons – Europa, Ganymede and Io – since its launch in 2016. The fourth moon, Callisto, will be explored by the European Space Agency’s (ESA) Jupiter ICy moons Explorer mission during 21 flybys from July 2031 to December 2034. The JUICE mission will include flybys of Jupiter’s other moons, such as Europa and Ganymede, followed by flybys of Ganymede for more detailed study. NASA is also planning the Europa Clipper mission, which will focus solely on the Europa moon. However, Io is not on the list of future missions.

NASA has considered several missions to Io in the past as part of the VERITAS program, but recently the Io Volcano Observer (IVO) and DAVINCI+ missions were rejected in favor of two missions to Venus. Juno’s orbital period around Jupiter is 38 days, and 11 more flybys are planned in 2024. The next flight, the 58th, scheduled for February 3, will make the second and final approach to Io from just 1,500 kilometers away.