Volcanic activity on Io — the innermost Galilean moon of Jupiter and the most volcanically active body in the Solar System — is unlikely to be sourced from a global magma ocean just below the surface, according to a new analysis of Juno and Galileo Doppler data from the Deep Space Network and astrometric observations.
Slightly larger than Earth’s Moon, Io is the most volcanically active body in the Solar System.
It is the innermost of Jupiter’s Galilean moons, which in addition to Io include Europa, Ganymede and Callisto.
Locked in a gravitational tug of war among Jupiter, Europa and Ganymede, Io is constantly being squeezed, leading to frictional heat buildup in its interior — believed to be the cause for its sustained and widespread volcanic activity.
The moon’s volcanic activity was first discovered in 1979, when Linda Morabito, an engineer on NASA’s Voyager mission, spotted an eruption plume in one of the images taken by the spacecraft during its famous Grand Tour of the outer planets.
Since then, countless observations have been made that document Io’s restless nature, from both space and Earth-based telescopes.
“Io is the innermost Galilean moon, orbiting Jupiter every 42.5 hours,” said Juno co-investigator Dr. Ryan Park from NASA’s Jet Propulsion Laboratory and colleagues.
“It has a mean diameter of 3,643 km and a bulk density of 3,528 kg/m3, making it about 5% larger in both diameter and density than the Moon.”
“Due to Io’s eccentric orbit, its distance from Jupiter varies by about 3,500 km, leading to variations in Jupiter’s gravitational pull.”
“Similar to tides on the Moon raised by Earth, these gravitational variations cause tidal deformation on Io, which is theorized to serve as the primary energy source for the intense volcanic activity and infrared emission observed on Io’s surface.”
The amount of tidal energy may be sufficient to cause melting of Io’s interior, potentially forming a subsurface magma…
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