On May 16, a monumental moment in space exploration unfolded as NASA's Juno spacecraft completed its closest-ever flyby of Io, one of Jupiter's enigmatic and volcanic moons.
On May 16, NASA’s Juno spacecraft executed its closest-ever flyby of Jupiter’s volcanic moon Io, swooping as close as 35,000 kilometers. Now in its third year, the probe’s mission aims to investigate Jupiter’s interior and ring system, where some of the gas giant’s inner moons orbit.
Juno’s Extended Mission to Jupiter
Juno’s tally of Jupiter flybys has reached 50. During these journeys, it has gathered data from three of the four Galilean moons – the icy realms of Europa and Ganymede and the fiery Io.
Io – The Solar System’s Volcanic Powerhouse
Juno’s principal investigator Scott Bolton describes Io as the “most volcanic celestial body in our solar system.” Observations from multiple flybys over time provide insights into the variations in volcanic activity, including eruption frequency, brightness, heat, lava flow changes, and patterns of volcanic grouping.
Io’s Tormented Landscape
Io, slightly larger than Earth’s moon, is under constant gravitational stress. Jupiter, the largest planet in the solar system, and its Galilean moons, Europa and Ganymede, pull Io in different directions. This gravitational tug-of-war results in Io’s continuous stretching and squeezing, contributing to the creation of its many erupting volcanoes.
Juno’s Instruments: Tools for Comprehensive Study
Juno’s design, initially for Jupiter study, has proven valuable for examining the planet’s moons. Its onboard instruments, including JunoCam, Jovian InfraRed Auroral Mapper (JIRAM), Stellar Reference Unit (SRU), and Microwave Radiometer (MWR), are critical in studying Io’s volcanoes and their interactions with Jupiter’s powerful magnetosphere and auroras.
The Journey Continues: Juno’s Upcoming Flybys
“As we get closer and closer to Io with successive orbits, we are entering another exciting part of Juno’s mission,” Bolton said. The upcoming flybys in July, October, and December, culminating in a February flyby just 1,500 kilometers from Io’s surface, promise spectacular views of Io’s volcanic activity and invaluable data.
Juno’s Milestones
During Jupiter flybys, Juno hovers as close as about 3,400 kilometers over the planet’s cloud tops, probing beneath the cloud cover with its instruments. The probe, which has been orbiting Jupiter for over 2,505 Earth days, covering 820 million kilometers, arrived at Jupiter on July 4, 2016. After its flybys of Io on May 16 and July 31, Juno’s orbital period will stabilize at 32 days.
Juno’s Extended Mission: A Look at Other Celestial Bodies
Juno’s acting project manager Matthew Johnson emphasizes that Io is just one of many celestial bodies Juno is investigating during its extended mission. Alongside providing new perspectives of Jupiter, the spacecraft will navigate Jupiter’s rings to gain insights into their origin and composition.
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