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A NASA spacecraft is preparing for the first in a series of close encounters with the most volcanic place in the solar system. The Juno spacecraft will fly by Jupiter’s moon Io on Thursday, December 15.
The maneuver will be one of nine flybys of Io by Juno over the next year and a half. Two of the encounters will be from a distance of just 930 miles (1,500 kilometers) from the moon’s surface.
Juno captured a brilliant infrared view of Io on July 5 from a distance of 50,000 miles (80,000 kilometers). The brightest spots in that image correspond to the highest temperatures on Io, which is home to hundreds of volcanoes, some of which can spew fountains of lava tens of kilometers high.

Scientists will use Juno’s observations of Io to learn more about that network of volcanoes and how their eruptions interact with Jupiter. The moon is constantly pulled by Jupiter’s massive gravitational pull.
“The team is really excited that Juno’s extended mission will include studying the moons of Jupiter. With each close flyby, we’ve been able to gain a wealth of new information,” Scott Bolton, Juno principal investigator at the Southwest Research Institute in San Antonio, said in a statement.
“The Juno sensors are designed to study Jupiter, but we are delighted at how well they can pull double duty when observing Jupiter’s moons.”
The spacecraft recently captured a new image of Jupiter’s northernmost cyclone on September 29. Jupiter’s atmosphere is dominated by hundreds of cyclones and many cumulus clouds at the planet’s poles.

The Juno spacecraft has been orbiting Jupiter since 2016 to discover more details about the giant planet and is focused on flybys of Jupiter’s moons during the extended part of its mission, which began last year and is expected to last until the end of 2025.
Juno flew by Jupiter’s moon Ganymede in 2021, followed by Europa earlier this year. The spacecraft used its instruments to peer beneath the icy crust of both moons and gathered data on the interior of Europa, where a salty ocean is believed to exist.
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The ice sheet that forms Europa’s surface is between 10 and 15 miles (16 and 24 kilometers) thick, and the ocean on which it sits is estimated to be between 40 and 100 miles (64 to 161 kilometers) deep. .
The data and images captured by Juno could help inform two separate missions heading to Jupiter’s moons in the next two years: the European Space Agency’s ICy JUpiter Moon Explorer and NASA Europa Clipper Mission.
The first, due to launch in April 2023, will spend three years exploring Jupiter and three of its icy moons, Ganymede, Callisto and Europa, in depth. All three moons are believed to have oceans beneath their ice-covered crusts, and scientists want to explore whether Ganymede’s ocean is potentially habitable.
Europa Clipper will launch in 2024 for a dedicated series of 50 flybys around the moon after arriving in 2030. Eventually, the transition from an altitude of 1,700 miles (2,736 kilometers) to just 16 miles (26 kilometers) above the surface of the moon, Europa Clipper may be able to help scientists determine whether an inland ocean actually exists there and whether the moon could support life.