In 1979, NASA Jet Propulsion Laboratory (JPL) scientist Linda Morabito found volcanic exercise on Jupiter’s innermost moon, Io. But Io isn’t simply volcanically lively—it’s the most volcanically lively physique in your complete photo voltaic system—and scientists now have a greater appreciation of the subsurface workings of the Moon’s lava sources.
NASA scientists have decided that Io’s roughly 400 lively volcanoes are possible fueled by particular person chambers of sizzling magma, and never a single large underground shared magma ocean. The discovery, printed in Nature on December 12, solves a thriller that has puzzled researchers for over 4 a long time. Their findings push scientists to rethink not simply their understanding of the Jovian moon, however of different celestial our bodies, as nicely.
Io is about the identical measurement as Earth’s Moon, and is marked by seemingly steady volcanic exercise. Astronomer Galileo Galilei found it in 1610, in 2011—some 4 centuries later—NASA launched its Juno mission. The spacecraft has been exploring the Jovian system since 2016, beaming jaw-dropping photographs again to Earth in addition to stunning revelations about our photo voltaic system’s largest planet.
“Since Morabito’s discovery, planetary scientists have questioned how the volcanoes had been fed from the lava beneath the floor,” Scott Bolton, Juno principal investigator from the Southwest Research Institute in San Antonio, who participated within the examine, mentioned in a NASA JPL assertion. “Was there a shallow ocean of white-hot magma fueling the volcanoes, or was their supply extra localized? We knew knowledge from Juno’s two very shut flybys might give us some insights on how this tortured moon really labored.”
In December 2023 and February 2024, Juno engaged in mentioned flybys of Io, reaching as shut as 930 miles (1,500 kilometers) to its volcano-dotted floor. During these maneuvers, Juno gathered knowledge to deduce the moon’s gravity based mostly on the way it impacted the spacecraft’s acceleration, revealing vital details about Io’s “tidal flexing.”
Tidal flexing occurs when a celestial physique is stretched and deformed by the gravitational pull of one other close by physique. The friction from the motion generates warmth, so the phenomenon is also called tidal heating. Io, for instance, follows an elliptical orbit round Jupiter, and the variation in distances from Jupiter (and consequently of Jupiter’s gravitational pull) alongside this orbit continually squeezes the moon, inflicting excessive tidal flexing.
“This fixed flexing creates immense vitality, which accurately melts parts of Io’s inside,” mentioned Bolton. “If Io has a worldwide magma ocean, we knew the signature of its tidal deformation could be a lot bigger than a extra inflexible, principally strong inside. Thus, relying on the outcomes from Juno’s probing of Io’s gravity area, we might have the ability to inform if a worldwide magma ocean was hiding beneath its floor.” In different phrases, the higher the tidal deformation, the extra possible Io’s volcanoes had been fueled by a bigger magma supply, equivalent to an ocean, and never simply particular person magma chambers.
Back on Earth, the staff in contrast Juno’s knowledge with outcomes from earlier missions and floor telescopes. The researchers conclude that Io’s tidal flexing factors to the presence of particular person magma chambers slightly than a single large magma ocean.
“Juno’s discovery that tidal forces don’t all the time create world magma oceans does greater than immediate us to rethink what we find out about Io’s inside,” mentioned Ryan Park, a Juno co-investigator from JPL who co-led the examine. “It has implications for our understanding of different moons, equivalent to Enceladus and Europa, and even exoplanets and super-Earths. Our new findings present a possibility to rethink what we find out about planetary formation and evolution.”
It stays to be seen what different revealing data Juno will glean from the Jovian system on its subsequent shut flyby of Jupiter on December 27.
