NASA sees signs of twin volcanic plumes on Jupiter's moon Io
On Saturday, NASA's Juno orbiter captured a second close-up of Io, Jupiter's third-largest moon and our solar system's most volcanic world.
The Juno spacecraft, which arrived at the gas giant in 2016, is on an extended mission to explore Jupiter's rings and moons. The final flyby, which complemented the mission's first approach on December 30, provided even more images of the moon's hellish landscape.
Io's violent expulsion of sulfur and additional compounds gives the moon its orange, yellow and blue hues. The process is similar to what happens around Hawaii's volcanoes or the geysers in Yellowstone National Park, according to Scott Bolton, a physicist at the Southwest Research Institute who leads the Juno mission. “That must be what Io is like – on steroids,” he said. He added that it probably smells like those places too.
Sunday was the most recent photos from Juno are already ripe for discovery. Dr. Bolton spotted what appeared to be a double volcanic plume spewing into space on Io's surface – something Juno has never seen before. Other scientists are noticing new lava flows and changes in known features noted during previous space missions, such as the Galileo probe, which flew close to Io numerous times in the 1990s and 2000s.
“That's the beauty of Io,” says Jani Radebaugh, a planetary scientist at Brigham Young University who is not part of the Juno mission but is working with the team on Io observations. Unlike our own moon, which remains frozen in time, said Dr. Radebaugh: 'Io changes every day, every minute, every second.'
Images from the double flight, which brought the spacecraft within about 900 miles (1,500 kilometers) of Io, will be combined with earlier snapshots NASA had taken of Jupiter's moon. The goal, Dr. Bolton said, is to understand “what is really behind the engine that powers all volcanoes, because they are everywhere.”
That could be a global magma ocean just beneath Io's crust — or just bits of molten rock beneath the surface, like the ones that fuel Earth's volcanoes. It can take weeks, even months, before scientists start finding answers in the data.
This is the last close flyby that Juno will make of Io. But the mission will continue to conduct longer-range observations every 60 days, giving mission specialists a view of the ever-changing moon as a whole.
That data will be just as valuable, according to Dr. Bolton.
“All the images are great,” he says. “We never really know what to expect.”