October 27, 2026 — Since its launch in 2011 and arrival at Jupiter in 2016, NASA’s Juno mission, led by the Southwest Research Institute, has profoundly advanced our understanding of Jupiter and its moons. SwRI Associate Vice President Dr. Scott Bolton is Juno’s principal investigator and has led the mission since its inception. Bolton is presenting an invited review of Juno results at the 58th Annual Division for Planetary Sciences Meeting in Spokane, Washington, at 2 p.m. on Oct. 28, 2026.
“Juno has transformed our understanding of Jupiter and how giant planets work through major discoveries spanning the gas giant’s interior structure, atmosphere, magnetosphere and aurora,” Bolton said. “Juno’s dramatic new view of Jupiter radically changes our concept of how giant planets work, both within our solar system and beyond.” Contrary to pre-Juno beliefs, Jupiter’s atmosphere is not well mixed, and the composition of its atmosphere does not appear to be the same as its deep interior, Bolton said. This major puzzle challenges theories about how Jupiter formed and evolved.
More recently, the natural evolution of Juno’s orbit around Jupiter expanded the ability to employ Juno’s arsenal of scientific tools to new targets and new science objectives as three of Jupiter’s largest moons — Ganymede, Europa and Io — all came into view. Juno’s flybys of the moons determined the thickness of the ice shell layers hiding their water oceans. The average thickness of Ganymede’s ice shell is ~100 km thick and the average for Europa’s ice shell is ~29 km thick. Numerous distant flybys of Io, the most volcanic body in the solar system, monitored volcanic activity and provided the first views of the volcanoes covering its poles. Two close flybys of Io determined that the volcanic eruptions are driven by localized seas of magma as opposed to a global magma ocean.
Juno discovered early on that the orange and white bands that characterize Jupiter’s outer atmosphere extend thousands of miles into the gas giant’s atmosphere. “The Juno data show that what seemed like a weather pattern on Jupiter extends to well below the depth where sunlight penetrates, which means that something other than weather may be driving these forces,” Bolton said. Juno also discovered lightning in the shallow clouds of Jupiter’s turbulent atmosphere, which was unexpected due to frigid temperatures. On Earth, lightning production requires clouds with liquid water. The Juno team discovered that the cloud tops of Jupiter’s upper atmosphere include an ammonia-water solution that seems to act as an anti-freeze, allowing lightning to trigger in very cold temperatures.
Juno’s orbital evolution also provided an opportunity to obtain 3-D maps of Jupiter’s northern polar cyclones indicating these cyclones have warm cores similar to Earth’s tropical storms. As Juno passes behind Jupiter, radio occultations of the atmosphere are combined with microwave measurements to obtain pole-to-equator atmospheric temperature profiles. The results suggest Jupiter’s polar region is generally warmer than its equator.
Juno is now passing through the region very close to Jupiter where the most intense radiation belts co-exist with Jupiter’s rings and small rocky moons. Juno is well equipped to cope with even the most intense radiation as the spacecraft was designed with the first ever “radiation vault” made out of titanium. The novel concept is a great success and is being used by missions now enroute to the Jovian system (NASA’s Europa Clipper and ESA’s JUICE missions).
Juno is revolutionizing spacecraft operations by learning how to reverse the degradation of spacecraft components caused by high-energy radiation. This experience and radiation mitigation know-how is providing new insights for operations of all spacecraft, including commercial satellites orbiting Earth, Bolton said. “As Juno travels through the most intense radiation regions in the entire solar system, we are learning how best to design and operate spacecraft for this environment and even how to reverse degradation that occurs,” Bolton said. “This is relevant not only to future planetary science, but also to commercial satellites right here around the Earth.”
For more information, visit Planetary Science or contact Mike W. Thomas, +1 210 522 2255, Communications Department, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238-5166.