Juno completes close Io flyby, new images

NASA’s Juno spacecraft has made another close pass by Io, Jupiter’s innermost large moon, and the first images circulating on May 20 came through the mission’s public processing pipeline rather than a formal NASA image release. JunoCam raw files are posted to the Mission Juno site for anyone to work on, and the project explicitly invites citizen scientists to download, process and upload their own versions. (missionjuno.swri.edu) That matters because Io is not just another moon in the frame. NASA describes it as the most volcanically active world in the solar system, with hundreds of volcanoes driven by tidal squeezing from Jupiter and the gravitational pulls of Europa and Ganymede. Some eruptions send lava fountains dozens of miles high, and Juno’s recent flybys have been aimed at tracking how those eruptions reshape the surface over time. (solarsystem.nasa.gov) The new pictures being shared now are a mix of raw spacecraft data and citizen-scientist enhancements. That is standard for JunoCam: the camera’s public gallery carries both unprocessed spacecraft images and community-produced versions, with NASA saying those outside contributions have been used in articles and scientific reporting. In other words, the dramatic plume and hotspot views now moving around online are part of the mission’s normal workflow, not an unofficial side project. (missionjuno.swri.edu) The scientific backdrop is unusually strong. NASA said in January 2025 that Juno’s JIRAM infrared instrument had spotted a volcanic hot spot in Io’s southern hemisphere larger than Lake Superior, producing eruptions with about six times the total energy output of all the world’s power plants. Mission principal investigator Scott Bolton said then that the latest data represented “the most powerful volcanic event ever recorded” on Io. (nasa.gov) Juno has been building toward this by revisiting Io repeatedly during its extended mission. NASA said the spacecraft made ultra-close Io flybys in December 2023 and February 2024, passing within about 930 miles, or 1,500 kilometers, of the surface. The mission has used those repeat passes to compare the same regions and look for new plume deposits, fresh lava flows and other visible surface changes. (science.nasa.gov) One detail worth watching in the latest imagery is the split between visible-light and infrared evidence. JunoCam can show surface texture, color and in some cases plume structure, while JIRAM is the instrument that maps heat from active volcanic regions. NASA has already published JIRAM views of Io’s south polar region showing multiple hot spots during the Dec. 27, 2024 flyby, and those thermal detections are what let scientists connect bright infrared signatures to active eruptions. (jpl.nasa.gov) The next step is likely more processing before a fuller NASA release. Mission Juno’s site says raw and processed images appear there as they become available, and Juno’s extended mission is continuing its observations of Jupiter’s inner moons, including Io. That means the images posted on May 20 are probably the first look, not the last word, on what this flyby captured. (missionjuno.swri.edu)