Magnetotail Reconnection at Jupiter: A survey of magnetic field and plasma flow signatures observed by Juno

Magnetic reconnection is an important physical process that allows for the release of mass and energy from a planetary magnetotail. At Jupiter, tail reconnection is thought to be driven by an internal mass loading and release process, called the Vasyliunas cycle, which is expected to occur with a typical 2-4 day recurrence period. Galileo magnetic field and energetic particle data have shown evidence of hundreds of reconnection events occurring in Jupiter's magnetotail and provided initial estimates of event properties like their size, recurrence time, and location. However, because of low resolution in the Galileo plasma density and velocity measurements, quantities like the mass loss rate from plasmoids remain poorly constrained, though initial estimates suggest that plasmoids can only account for a small fraction of the mass input from Io. Here we present a survey of Juno reconnection events observed during the spacecraft's first 2 years in Jupiter orbit. Juno provides the first comprehensive magnetic field and plasma measurements of reconnection in Jupiter's magnetotail and therefore provides important context that can aid in reanalysis of the Galileo reconnection events, most of which were identified using magnetic field data alone. Additionally, the spacecraft orbit is favorable for viewing reconnection signatures since the Juno spacecraft makes many crossings of the magnetic equator in the middle magnetosphere. The new Juno observations further complement the Galileo data by providing improved measurements of the plasma density and velocity, which is critical for constraining the mass lost by plasmoids, and by providing additional spatial coverage in the magnetotail. Therefore the Juno observations will provide new insight into the drivers of magnetotail reconnection and its role in the overall transport of mass and magnetic flux in Jupiter's magnetosphere.