1. The SwRI-led Juno mission discovered that Jupiter’s signature bands disappear near its poles. This JunoCam image, processed by citizen scientist Bruce Lemons, show a chaotic scene of swirling storms up to the size of Mars against a bluish backdrop.
Credit Line:Â Image Courtesy of NASA/SwRI
2. The SwRI-led UVS spectrograph images Jupiter’s massive auroras. Collected during Juno’s third orbit around the gas giant, this false-color image is inset with an image of Earth’s south pole aurora, approximately to scale, collected September 11, 2005. The streaky colors away from the Jovian auroral region are associated with penetrating electrons.
King of the planets even more exotic than expected. NASA’s Juno mission, led by Southwest Research Institute’s Dr. Scott Bolton, is rewriting what scientists thought they knew about Jupiter specifically, and gas giants in general. The Juno spacecraft has been in orbit around Jupiter since July 2016, passing within 3,000 miles of the equatorial cloudtops. “Discoveries about its core, composition, magnetosphere, and poles are as stunning as the photographs the mission is generating.”
The solar-powered spacecraft’s 8 scientific instruments are designed to study Jupiter’s interior structure, atmosphere, and magnetosphere. Two instruments developed and led by SwRI are working in concert to study Jupiter’s auroras. The Jovian Auroral Distributions Experiment (JADE) is a set of sensors detecting the electrons and ions associated with Jupiter’s auroras. The Ultraviolet Imaging Spectrograph (UVS) examines the auroras in UV light to study Jupiter’s upper atmosphere and the particles that collide with it. Scientists expected to find similarities to Earth’s auroras, but Jovian auroral processes are proving puzzling.
“Although many of the observations have terrestrial analogs, it appears that different processes are at work creating the auroras,” said SwRI’s Dr. Phil Valek, JADE instrument lead. “With JADE we’ve observed plasmas upwelling from the upper atmosphere to help populate Jupiter’s magnetosphere. However, the energetic particles associated with Jovian auroras are very different from those that power the most intense auroral emissions at Earth.”
Also surprising, Jupiter’s signature bands disappear near its poles. JunoCam images show a chaotic scene of swirling storms up to the size of Mars towering above a bluish backdrop. Since the first observations of these belts and zones many decades ago, scientists have wondered how far beneath the gas giant’s swirling façade these features persist. Juno’s microwave sounding instrument reveals that topical weather phenomena extend deep below the cloudtops, to pressures of 100 bars, 100 times Earth’s air pressure at sea level. “However, there’s a north-south asymmetry. The depths of the bands are distributed unequally,” Bolton said. “We’ve observed a narrow ammonia-rich plume at the equator. It resembles a deeper, wider version of the air currents that rise from Earth’s equator and generate the trade winds.”
Juno is mapping Jupiter’s gravitational and magnetic fields to better understand the planet’s interior structure and measure the mass of the core. Scientists think a dynamo – a rotating, convecting, electrically conducting fluid in a planet’s outer core – is the mechanism for generating the planetary magnetic fields. “Juno’s gravity field measurements differ significantly from what we expected, which has implications for the distribution of heavy elements in the interior, including the existence and mass of Jupiter’s core,” Bolton said. The magnitude of the observed magnetic field was 7.766 Gauss, significantly stronger than expected. But the real surprise was the dramatic spatial variation in the field, which was significantly higher than expected in some locations, and markedly lower in others. “We characterized the field to estimate the depth of the dynamo region, suggesting that it may occur in a molecular hydrogen layer above the pressure-induced transition to the metallic state.” http://www.swri.org/press-release/swri-led-juno-mission-jupiter-delivers-first-science-results
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