The Ultraviolet Spectrograph on NASA’s Juno Mission

The ultraviolet spectrographinstrument on the Juno mission (Juno-UVS) is a long-slit imaging spectrographdesigned to observe and characterize Jupiter’s far-ultraviolet (FUV) auroral emissions. These observations will be coordinated and correlated with those from Juno’s other remote sensing instruments and used to place in situ measurements made by Juno’s particles and fields instruments into a global context, relating the local data with events occurring in more distant regions of Jupiter’s magnetosphere. Juno-UVS is based on a series of imaging FUV spectrographscurrently in flight—the two Alice instruments on the Rosetta and New Horizons missions, and the Lyman Alpha MappingProject on the Lunar Reconnaissance Orbiter mission. However, Juno-UVS has several important modifications, including (1) a scan mirror (for targeting specific auroral features), (2) extensive shielding (for mitigation of electronics and data quality degradation by energetic particles), and (3) a cross delay line microchannel plate detector(for both faster photon countingand improved spatial resolution). This paper describes the science objectives, design, and initial performance of the Juno-UVS.