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Fire, mountains, and polar cyclones found by the Juno spacecraft

Scientists have shared remarkable findings from NASA’s Juno mission to Jupiter. The solar-powered Juno spacecraft has provided new insights into the Jovian moon Io, Jupiter’s polar cyclones, and the planet’s water abundance.

Jaw-dropping Io discoveries from the Juno mission

Scott Bolton, Juno’s principal investigator from the Southwest Research Institute in San Antonio, unveiled the new discoveries during a news conference at the European Geophysical Union General Assembly in Vienna.

The team transformed data collected during two recent flybys of Io into captivating animations that showcase the moon’s most dramatic features: a mountain and a nearly glass-smooth lake of cooling lava.

“Io is simply littered with volcanoes, and we caught a few of them in action. We also got some great close-ups and other data on a 200-kilometer-long (127-mile-long) lava lake called Loki Patera,” said Bolton.

“There is amazing detail showing these crazy islands embedded in the middle of a potentially magma lake rimmed with hot lava. The specular reflection our instruments recorded of the lake suggests parts of Io’s surface are as smooth as glass, reminiscent of volcanically created obsidian glass on Earth,” he continued.

Unraveling Io’s dramatic landscapes

Juno made extremely close flybys of Io in December 2023 and February 2024, getting within about 930 miles (1,500 kilometers) of the surface and obtaining the first close-up images of the moon’s northern latitudes.

Maps generated with data collected by Juno’s Microwave Radiometer (MWR) instrument reveal that Io not only has a relatively smooth surface compared to Jupiter’s other Galilean moons but also has poles that are colder than middle latitudes.

Exploring Jupiter’s enigmatic polar cyclones

As Juno’s extended mission progresses, the spacecraft flies closer to Jupiter’s north pole with each pass. This changing orientation allows the MWR instrument to improve its resolution of the planet’s northern polar cyclones.

The data enables multiwavelength comparisons of the poles, revealing that not all polar cyclones are created equal.

“Perhaps most striking example of this disparity can be found with the central cyclone at Jupiter’s north pole. It is clearly visible in both infrared and visible light images, but its microwave signature is nowhere near as strong as other nearby storms, said Steve Levin, Juno’s project scientist at NASA’s Jet Propulsion Laboratory in Southern California.

“This tells us that its subsurface structure must be very different from these other cyclones. The MWR team continues to collect more and better microwave data with every orbit, so we anticipate developing a more detailed 3D map of these intriguing polar storms,” Levin continued.

Solving the puzzle of Jupiter’s water abundance

One of the mission’s primary science goals is to collect data that could help scientists better understand Jupiter’s water abundance.

To do this, the Juno science team isn’t hunting for liquid water. Instead, they are looking to quantify the presence of oxygen and hydrogen molecules (the molecules that make up water) in Jupiter’s atmosphere. An accurate estimate is critical to piecing together the puzzle of our solar system’s formation.

“The probe did amazing science, but its data was so far afield from our models of Jupiter’s water abundance that we considered whether the location it sampled could be an outlier. But before Juno, we couldn’t confirm,” said Bolton.

“Now, with recent results made with MWR data, we have nailed down that the water abundance near Jupiter’s equator is roughly three to four times the solar abundance when compared to hydrogen. This definitively demonstrates that the Galileo probe’s entry site was an anomalously dry, desert-like region,” he concluded.

Hydrogen and oxygen are key to Jupiter’s past

The results support the belief that during the formation of our solar system, water-ice material may have been the source of the heavy element enrichment (chemical elements heavier than hydrogen and helium that were accreted by Jupiter) during the gas giant’s formation and/or evolution.

However, the formation of Jupiter remains puzzling, as Juno results on the core of the gas giant suggest a very low water abundance — a mystery that scientists are still trying to sort out.

Data collected during the remainder of Juno’s extended mission may help shed additional light on the structure of Jupiter’s dilute core and enable scientists to compare the planet’s water abundance near the polar regions to the equatorial region.

During Juno’s most recent flyby of Io on April 9, the spacecraft came within about 10,250 miles (16,500 kilometers) of the moon’s surface. It will execute its 61st flyby of Jupiter on May 12.

Jupiter, Io, and the Juno spacecraft

NASA’s Juno mission continues to push the boundaries of our understanding of Jupiter and its moons. With each flyby, Juno gathers invaluable data that scientists eagerly analyze, uncovering new insights into the gas giant’s polar cyclones, water abundance, and the enigmatic moon Io.

As the spacecraft persists in its exploration, the scientific community anticipates more stunning discoveries that will deepen our knowledge of Jupiter and provide new details on the formation and evolution of our solar system.

The Juno mission exemplifies the indomitable spirit of human curiosity and the relentless pursuit of scientific truth, promising to rewrite the textbooks on the largest planet in our cosmic neighborhood.

The full study was presented at the European Geophysical Union General Assembly.


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