The Juno-Supporting Earth-Based Observing Campaign

To support the Juno mission and provide necessary spatial and spectral context to measurements made by the spacecraft, the science team has established and coordinated an international network of observational astronomers and Earth-based observatories. This network of supporting observations of the Jovian system continues to expand. The measurements cover a broad spectral range with over 60 groups contributing to the campaign. The support provided by these observations constitutes several specific enhancements to Juno’s own data. (1) They provide knowledge about the evolution of features detected by the spacecraft at a single point in time. (2) Contextual information is gathered about the larger spatial environment surrounding the often very limited regions covered by Juno’s own instruments. (3) The spectral range covered by Juno’s suite of instruments is expanded, now including observations that cover X-ray through radio wavelengths. Observations at intermediate wavelengths, such as the mid-infrared, can detect thermal signatures that can measure temperatures in the upper troposphere through stratosphere unambiguously. (4) Supporting measurements also assess the extent to which distant phenomena taking place within the Jovian system may influence atmospheric or auroral properties detected by Juno’s instruments, such as the mass loading from Io by tracking its observed volcanic activity and the opacity of its torus. Observations of Jupiter’s neutral atmosphere included images and spectra of reflected sunlight from the near-ultraviolet through the near-infrared and thermal emission from 5 µm through the radio region.  The ultimate goal of these Earth-based measurements is to relate properties of the deep atmosphere (that are the focus of Juno’s mission) to the state of the “weather layer” at much lower pressures  Of special consideration during Juno’s extended mission are observations of thermal emission that cover narrow regions where temperature profiles are created from the phase change of the high-beam antenna’s radio signal as it is being occulted by Jupiter’s atmosphere. The spectral region and timeline of all of these observations are summarized in the web site: https://www.missionjuno.swri.edu/planned-observations. Besides a global network of professional astronomers, the Juno mission also benefited significantly from a network of dedicated amateur astronomers who provided a quasi-continuous picture of the evolution of features observed by Juno’s instruments. Examples of support will be shown from the primary and extended mission.