Jupiter and its moon Ganymede interact magnetically


Data obtained by NASA’s Juno spacecraft has found evidence that there is a magnetic reconnection between the moon Ganymede and the planet Jupiter.

Taking advantage of Juno’s flyby of Ganymede in June 2021, a team led by the Southwest Research Institute he examined the electron and ion particles and magnetic fields as the magnetic field lines of Jupiter and Ganymede merged, snapped, and reoriented, heating and accelerating the region’s charged particles.

“Ganymede is the only moon in our solar system that has its own magnetic field,” explains Dr. Scott Bolton, Juno Principal Investigator at SwRI. “The breaking and reconnection of Ganymede’s magnetic field lines with those of Jupiter creates magnetospheric fireworks.”

Magnetic reconnection is an explosive physical process that converts stored magnetic energy into kinetic energy and heat. Ganymede’s mini-magnetosphere interacts with Jupiter’s massive magnetosphere, at the magnetopause, the boundary between the two regions.

“We interpreted the presence of accelerated electrons traveling along the magnetic field at Ganymede’s magnetopause as evidence that magnetic reconnection was occurring there during the Juno flyby,” he said. it’s a statement Dr. Robert Ebert, lead author of a Geophysical Research Letters article describing the findings. “These observations further support the idea that magnetic reconnection at the Ganymede magnetopause may be a driver of dynamical processes in the local space environment around this moon of Jupiter.”

The SwRI-developed Jovian Auroral Distributions (JADE) Experiment aboard Juno observed enhanced electron flows, including electrons accelerated and aligned with the magnetic field. The reconnection observed by Juno is believed to be related to the generation of Ganymede’s aurora.

“The accelerated electrons observed by JADE are similar to those observed by NASA’s Magnetospheric Multiscale (MSS) spacecraft during reconnection at Earth’s magnetopause,” explains Stephen Fuselier, co-author of the paper. “This is one of the most interesting results of the Ganymede flyby: Despite the huge differences between Ganymede and Earth, we find common ground in the universal process of magnetic reconnection.”

During the flyby of Juno, the SwRI-led Ultraviolet Spectrograph (UVS) observed Ganymede’s auroral emissions, which are expected to be produced by electrons being accelerated through magnetic reconnection. SwRI has built two additional UVS instruments to operate in Jupiter orbit aboard ESA’s JUpiter ICy moons Explorer (JUICE) and NASA’s Europa Clipper. The European Space Agency’s JUICE mission is scheduled to launch in April 2023 and arrive at Jupiter in 2031. NASA’s Europa Clipper, it will launch in October 2024 and arrive at Jupiter in 2030.

Nothing is simple -or small- when you have the largest planet in the solar system as your neighbor“, said Thomas Greathouse, Juno scientist at SwRI. “This was the first measurement of this complicated interaction on Ganymede. This gives us a very early idea of ​​the information we hope to get from ESA’s JUICE mission.”

An article describing this research was published in Geophysical Research Letters.