From channelized lava on Io, to Jupiter’s upper atmosphere and aurora: Juno SRU observations of emissions in the visible to near infrared

In 2023 and 2024, the orbital evolution of Juno’s Extended Mission created unprecedented opportunities for high-resolution imaging of Io’s surface and the high northern latitudes of Jupiter. The Mission’s low-light Stellar Reference Unit (SRU) star camera captured the night sides of both bodies at wavelengths extending from the visible into the near infrared (450-1,000 nm; with peak sensitivity from ~570-800 nm). Juno’s highest resolution image of Io’s surface was acquired by the SRU during a close flyby in December 2023 at 895-1230 m pixel scale under high phase Jupiter-shine illumination. The sensitivity of the SRU at longer wavelengths enabled the first detection of thermal emission from an active lava channel on Io, corroborated by earlier lower-resolution JIRAM data at 4.78 microns. The SRU detected multiple additional thermal emission signatures from active lava breakouts in fresh flows at Zal Patera, and at the base of a vertical mountain fracture at South Zal Mons (suggesting volcanism induced by mountain tectonics). Recent observations of Jupiter’s night side have provided glimpses into the vertical structure of Jupiter’s northern aurora at <10 km/pixel and high altitude haze on Jupiter’s limb. Our presentation will discuss these Io and Jupiter findings, revealed by the SRU in low-light.