First Results From Juno Mission Reveal a Whole New Jupiter

This image shows Jupiter’s south pole, as seen by NASA’s Juno spacecraft from an altitude of 32,000 miles. The oval features are cyclones, up to 600 miles in diameter. Multiple images taken with the JunoCam instrument on three separate orbits were combined to show all areas in daylight, enhanced color, and stereographic projection. (NASA/JPL-Caltech/SwRI/MSSS/Betsy Asher Hall/Gervasio Robles)

(CN) – Early results from NASA’s Juno mission to Jupiter reveal Earth-sized polar cyclones, a “fuzzy” core and a massive, irregularly shaped magnetic field – all of which challenge previously held theories on the solar system’s largest planet.

The findings are detailed in more than 40 papers discussing the surprising data from NASA’s mission to Jupiter, which reveal greater complexity and variability than scientists had expected.

“It was a long trip to get to Jupiter, but these first results already demonstrate it was well worth the journey,” said Diane Brown, Juno program executive at NASA.

Launched Aug. 5, 2011, from Florida’s Cape Canaveral, Juno made a gravity-assist flyby of Earth in October 2013 to generate enough speed to complete its roundabout 1.7-billion-mile voyage to Jupiter. The spacecraft successfully braked into a highly elliptical orbit around the gas giant in April 2016.

The information retrieved during Juno’s first data-collection pass on Aug. 27 – when the spacecraft flew within 2,600 miles of Jupiter’s swirling cloud tops – will likely fuel considerable speculation and analysis of the planet as scientists await data from subsequent passes.

“We knew going in that Jupiter would throw us some curves,” said Scott Bolton, Juno principal investigator from the Southwest Research Institute in San Antonio. “But now that we are here we are finding that Jupiter can throw the heat, as well as knuckleballs and sliders. There is so much going on here that we didn’t expect that we have had to take a step back and begin to rethink of this as a whole new Jupiter.”

Among the surprising discoveries provided by Juno are Earth-sized swirling storms that cover both of Jupiter’s poles.

“We’re puzzled as to how they could be formed, how stable the configuration is, and why Jupiter’s north pole doesn’t look like the south pole,” Bolton said. “We’re questioning whether this is a dynamic system, and are we seeing just one stage and over the next year we’re going to watch it disappear, or is this a stable configuration and these storms are circulating around one another?”

Data from the Aug. 27, 2016, pass also show that Jupiter’s iconic belts and zones are unique and mysterious, with the belt near the equator spanning through the planet’s atmosphere, while the belts and zones at other latitudes seem to lead to other structures. The information suggests the ammonia in the gas giant’s atmosphere varies and continues to increase as far down as could be seen by Juno’s microwave radiometer, which is a few hundred miles.

While scientists knew Jupiter features the most intense magnetic field in the solar system, measurements of the planet’s magnetosphere indicate that it is even stronger than models predicted – and more irregular in shape. The data show that the magnetic field is about 10 times stronger than the strongest magnetic field found on Earth.

“Juno is giving us a view of the magnetic field close to Jupiter that we’ve never had before,” said Jack Connerney, Juno deputy principal investigator. “Already we see that the magnetic field looks lumpy; it is stronger in some places and weaker in others. This uneven distribution suggests that the field might be generated by dynamo action closer to the surface, above the layer of metallic hydrogen. Every flyby we execute gets us closer to determining where and how Jupiter’s dynamo works.”

Another question Juno is supposed to help answer is whether it has a core. Scientists have presented competing theories, which range from Jupiter having a small, compact core roughly the size of Earth, to the gas giant having formed without a core entirely. The data suggest the presence of a non-discrete, “fuzzy” core. Researchers say more information is needed to develop a precise understanding of the planet’s center.

As the scientific community digests the first results from Juno, further missions will likely add to the revelations described Thursday.

“Every 53 days, we go screaming by Jupiter, get doused by a fire hose of Jovian science, and there is always something new,” Bolton said. “On our next flyby on July 11, we will fly directly over one of the most iconic features in the entire solar system – one that every school kid knows – Jupiter’s Great Red Spot.

“If anybody is going to get to the bottom of what is going on below those mammoth swirling crimson cloud tops, it’s Juno and her cloud-piercing science instruments.”


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