Surface Features of Ganymede Revealed in Jupiter-Shine by Juno’s Stellar Reference Unit

Abstract

On 7 June 2021, Juno crossed the orbital path of Jupiter’s moon Ganymede, flying within 1,046 km of the surface. Juno’s low-light-sensitive Stellar Reference Unit (SRU) navigation camera captured an image of the satellite’s dark side in a region of Xibalba Sulcus illuminated solely by Jupiter-shine. Collected at high incidence angle with 670–920 m/pixel resolution, the image reveals terrain morphology, ejecta, and numerous small craters that cannot be discerned in the Voyager imagery used for the USGS global geologic map of Ganymede. The Juno data enable improved mapping of Ganymede’s surface and reinterpretation of material and crater ages in a region previously characterized as light “undivided” material due to poor image resolution. The illumination conditions achieved by the SRU observation geometry also reveal the detailed morphology of a 270-km elongated bright feature in this area. These newly resolved features contribute to an improved understanding of Ganymede’s complex history.