At the European Geophysical Union General Assembly held in Vienna last week, NASA’s Juno mission principal investigator Scott Bolton illustrated some new discoveries offered by the Juno space probe, including some regarding Io, Jupiter’s volcano-covered moon. Io was also studied by a team of researchers who used the ALMA radio telescope to map the movements of sulfur isotopes and reconstruct the tidal heating that generates the intense volcanic activity. The results were published in an article in the journal “Journal of Geophysical Research: Planets”.
During the last two Io flybys, the Juno space probe collected a lot of new information that enabled NASA to create animations of two of the most impressive geological features of this moon: a very steep mountain and a lava lake whose surface is almost as smooth as glass that was named Loki Patera.
In December 2023 and February 2024, the Juno space probe conducted two Io flybys, reaching approximately 1,500 kilometers above its surface. For the first time, close-up images of Io’s northern latitudes were obtained.
The JunoCam is the instrument of the Juno space probe used in particular to obtain images of Io’s surface useful for reconstructing the volcanic activity of this moon. The video below features Loki Patera, a depression on Io’s surface that is filled with magma. The reflection detected from the lake suggests that some parts of this moon’s surface are smooth as glass. On Earth, volcanoes can generate obsidian, which has that type of characteristic.
The mountain nicknamed Steeple Mountain represents a mystery because its formation is difficult to explain. The animation in the video below shows its very strange shape, reaching an altitude estimated between 5 and 7 kilometers with an extremely steep climb.
A team led by Katherine de Kleer of Caltech and Ery Hughes of GNS Science traced the movements of sulfur isotopes on Io using the ALMA radio telescope. This choice is due to the fact that on this moon, there’s a sulfur cycle where this element is released from volcanoes, processed in the thin atmosphere, and recycled into the mantle. Some of the sulfur escapes into space and the planet Jupiter’s powerful magnetosphere ionizes the particles of sulfur and other molecules, which continually hit Io’s atmosphere.
There are various sulfur isotopes on Io, and the ALMA radio telescope made it possible to map their movements separately. The sulfur lost to space is a lighter isotope than the one recycled in the mantle. The consequence is that the sulfur that remains becomes increasingly heavier.
According to the researchers, the heating generated by the tidal forces that power Io’s volcanic activity has continued for some billion years. Those forces are composed of Jupiter’s gravity but also the gravity of the other large nearby moons Ganymede and Europa. The consequence is that this moon has been volcanically active for almost all of its existence. Reconstructing the loss of elements such as sulfur helps reconstruct its history and the history of its volcanic activity.
Io is considered the most active object in the solar system with regard to volcanism and geological activity in general. Scientists specializing in different disciplines find it very interesting and for this reason, they follow the Juno mission with attention. The recent flybys offer new information to enrich the map published in January 2023.
