NASA’s Juno spacecraft will on Saturday, December 30, make the closest flyby of Jupiter’s moon Io that any spacecraft has made in over 20 years. The spacecraft will come within roughly 930 miles (1,500 kilometers) from the surface of the most volcanic world in our solar system. It is expected that the pass will allow Juno instruments to generate a firehose of data.
According to Juno’s principal investigator, Scott Bolton of the Southwest Research Institute in San Antonio, Texas, the Juno science team is studying how Io’s volcanoes vary by combining data from this flyby with the previous observations.
The team will be studying various aspects relating to the volcanoes, including how often they erupt, how bright and hot they are, how the shape of the lava flow changes, and how Io’s activity is connected to the flow of charged particles in Jupiter’s magnetosphere.
The spacecraft has been monitoring Io’s volcanic activity from distances ranging from about 6,830 miles (11,000 kilometers) to over 62,100 miles (100,000 kilometers), and has provided the first views of the moon’s north and south poles. The spacecraft has also performed close flybys of Jupiter’s icy moons Ganymede and Europa.
Juno will again make an ultra-close flyby of Io on February 3, 2024, in which it will again come within about 930 miles (1,500 kilometers) of the surface.
“With our pair of close flybys in December and February, Juno will investigate the source of Io’s massive volcanic activity, whether a magma ocean exists underneath its crust, and the importance of tidal forces from Jupiter, which are relentlessly squeezing this tortured moon,” said Bolton.
All three cameras aboard Juno will be active during the Io flyby. The Jovian Infrared Auroral Mapper (JIRAM), which takes images in infrared, will be collecting the heat signatures emitted by volcanoes and calderas covering the moon’s surface. The mission’s Stellar Reference Unit (a navigational star camera that has also provided valuable science) will obtain the highest-resolution image of the surface to date. And the JunoCam imager will take visible-light colour images, informed NASA.
Juno, the solar-powered spacecraft, will also explore the ring system where some of the gas giant’s inner moons reside. However, the gravitational pull of Io on Juno during the December 30 flyby will reduce the spacecraft’s orbit around Jupiter from 38 days to 35 days. Juno’s orbit will drop to 33 days after the February 3 flyby.