Abstract Juno's flyby of Ganymede revealed ion composition in its vicinity with the Jovian Auroral Distributions Experiment–Ion (JADE‐I) instrument. Throughout this flyby, we derive species‐resolved ion density and velocity moments by decomposing the time‐of‐flight data into contributions from individual ion species using species‐dependent fits. At the sub‐Jovian flank magnetopause—a region previously linked to reconnection by previous studies—Juno encountered a strong field‐aligned ion jet. Its direction and magnitude are consistent with Hall‐mediated flank magnetopause reconnection at Ganymede. As reconnection‐accelerated electrons have been associated with Ganymede's polar aurora, the persistence of auroral emission suggests reconnection, and associated ion acceleration may occur along an extended X‐line. These results imply reconnection at Ganymede can act not only as a localized driver of ion jets, but also as a distributed pathway for ion and neutral loss. Given the appropriate reconnection geometry, such a mechanism is likely operating at a broad range of magnetized astrophysical bodies immersed within plasma.
Oberg et al. (Thu,) studied this question.