On February 3, 2024, NASA’s Juno spacecraft made a second close flyby of Io, the fifth of Jupiter’s moons and the third largest. Like the previous flyby on December 30, 2023, this second pass was made at a distance of about 1,500 km (930 miles). During the twin flybys, the spacecraft’s JunoCam instrument returned spectacular high-resolution images and raw data. The flybys were designed to provide new insights into how Io’s volcanic engine works and whether a global magma ocean exists beneath the volcanic moon’s rocky, mountainous surface.
Io is the innermost of Jupiter’s four Galilean moons and the fourth largest moon in our Solar System.
It is approximately 3,630 km (2,556 miles) in diameter, only slightly larger than our own Moon.
Apart from Earth, it is the only known place in the Solar System with volcanoes that spew hot lava like that on our planet.
Io has more than 400 active volcanoes, which are caused by tidal heating, the result of a gravitational tug-of-war between Jupiter’s gravity and the smaller but precisely timed tugs of Europa and Ganymede.
The moon’s yellow, white, orange, and red coloration is produced by the frost of sulfur dioxide on its surface, elemental sulfur, and a variety of sulfur allotropes.
Volcanoes were first discovered on Io in 1979, and subsequent studies by NASA’s Galileo spacecraft and ground-based telescopes show that eruptions and lava fountains constantly occur, creating rivers and lakes of lava.
Only 13 giant eruptions were observed between 1978 and 2006, in part because only a handful of astronomers scan the Moon regularly.
NASA’s Juno spacecraft has been monitoring Io’s volcanic activity from distances ranging from about 11,000 km (6,830 miles) to more than 100,000 km (62,100 miles), and has provided the first views of Io’s north and south poles. Moon.
On December 30, 2023, Juno arrived within about 1,500 km of Io’s surface; The orbiter performed a second ultra-close flyby of the Moon on February 3, 2024.
The second pass was predominantly over Io’s southern hemisphere, while previous flybys were over the northern one.
“By combining data from these close flybys with our previous observations, the Juno science team is studying how Io’s volcanoes vary,” said Juno principal investigator Dr. Scott Bolton, a researcher at the Southwest Research Institute.
“We’re looking at how often they erupt, how bright and hot they are, how the shape of the lava flow changes, and how Io’s activity is related to the flow of charged particles in Jupiter’s magnetosphere.”
“We are investigating the source of Io’s enormous volcanic activity, whether a magma ocean exists beneath its crust, and the importance of Jupiter’s tidal forces, which are relentlessly squeezing this tortured moon.”
“There is evidence of an active column, high mountain peaks with well-defined shadows and lava lakes, some with apparent islands.”
Starting in April 2024, Juno will conduct a series of occultation experiments that will use Juno’s Gravity Science experiment to probe the composition of Jupiter’s upper atmosphere, which provides key information about the shape and interior structure of the planet.