Capturing the north polar expanse of Jupiter’s moon Io, this striking image, taken by NASA’s Juno on October 15, unveils three previously unseen mountain peaks near the day-night border. Juno, with 56 flybys of Jupiter under its belt, has meticulously documented close encounters with three of the gas giant’s largest moons.
A significant milestone awaits on Saturday, December 30, as Juno embarks on the closest flyby of Io in over two decades, bringing the spacecraft within approximately 930 miles (1,500 kilometers) of this intensely volcanic moon. This proximity promises a deluge of data, as Juno’s instruments stand poised to glean unprecedented insights from this daring journey.
Juno’s principal investigator, Scott Bolton of the Southwest Research Institute in San Antonio, Texas, underscores the significance of the upcoming Io flyby. By amalgamating data from this close encounter with previous observations, the Juno science team aims to unravel the dynamics of Io’s volcanoes—examining eruption frequency, luminosity, temperature, lava flow evolution, and the correlation between Io’s activity and Jupiter’s magnetosphere-charged particle flow.
This marks the first ultra-close flyby, with another scheduled for February 3, 2024, both bringing Juno within a mere 930 miles (1,500 kilometers) of Io’s surface. From distances ranging between 6,830 miles (11,000 kilometers) and over 62,100 miles (100,000 kilometers), Juno has been diligently monitoring Io’s volcanic activity and has provided unprecedented views of the moon’s polar regions. The spacecraft’s close encounters extend beyond Io, encompassing Jupiter’s icy moons Ganymede and Europa.
This captivating JunoCam image, taken on October 15, unveils a plume emanating from the unseen volcano Prometheus on Jupiter’s moon Io. The red arrow highlights the plume, faintly visible in the darkness below the terminator, the line demarcating day and night. Principal investigator Scott Bolton emphasizes Juno’s critical role in probing the origins of Io’s intense volcanic activity during its pair of close flybys in December and February.
Questions about the potential existence of a magma ocean beneath Io’s crust and the relentless tidal forces from Jupiter squeezing this moon will be at the forefront of Juno’s investigations. As the solar-powered spacecraft enters the third year of its extended mission, it is poised to delve into the mysteries of Jupiter’s origin and explore the enigmatic ring system housing some of the gas giant’s inner moons.
Juno’s Unveiling of Jupiter’s Moon Io Amidst Radiation Challenges.
Juno is gearing up for a comprehensive study of Jupiter’s moon Io during the upcoming flyby, with all three of its cameras set into action. The Jovian Infrared Auroral Mapper (JIRAM) will focus on capturing infrared images, unraveling the heat signatures emanating from Io’s volcanoes and calderas. Simultaneously, the Stellar Reference Unit, originally a navigational star camera but doubling as a valuable scientific tool, is poised to secure the highest-resolution image of Io’s surface to date. Complementing these, the JunoCam imager will contribute visible-light color images, collectively providing a multifaceted view of Io’s intricate features and volcanic activity.
JunoCam, included on the spacecraft with a focus on public engagement, was initially designed to operate for up to eight Jupiter flybys. The upcoming Io flyby will mark Juno’s 57th orbit around the gas giant, a journey through one of the solar system’s most challenging radiation environments.
Ed Hirst, project manager of Juno at NASA’s Jet Propulsion Laboratory, notes that the cumulative effects of this intense radiation have started to impact JunoCam over recent orbits, revealing a reduction in the imager’s dynamic range and the emergence of ‘striping’ noise in the images. Despite these challenges, Juno’s engineering team is actively developing solutions to mitigate radiation damage and prolong the imager’s functionality.
Juno’s Extended Mission Expands with Additional Distant Flybys.
Following extensive study and evaluation, the Juno team has modified the spacecraft’s planned trajectory for its extended mission, incorporating seven additional distant flybys of Jupiter’s moon Io, bringing the total to 18. Following the close pass on February 3, Juno will engage in flybys every other orbit, each progressively more distant.
Altitudes will vary, starting at approximately 10,250 miles (16,500 kilometers) above Io and concluding at around 71,450 miles (115,000 kilometers). The gravitational influence of Io during the December 30 flyby is anticipated to condense Juno’s orbit around Jupiter from 38 to 35 days, with a subsequent reduction to 33 days after the February 3 flyby. This strategic adjustment promises to yield valuable insights and optimize Juno’s scientific observations during its extended mission.
Juno’s revised trajectory will introduce a unique phenomenon as Jupiter momentarily eclipses the Sun for approximately five minutes during each perijove, the point when the spacecraft is closest to the planet. This solar blockage, a consequence of Juno’s altered course, marks the first time the solar-powered spacecraft will experience darkness since its Earth flyby in October 2013. Despite this brief hiatus of sunlight, it is deemed too short to significantly impact Juno’s overall operation.
Notably, with the exception of the February 3 perijove, similar solar eclipses are anticipated during each close flyby of Jupiter throughout the remainder of the extended mission, concluding in late 2025. An intriguing phase begins in April 2024 when Juno embarks on a series of occultation experiments utilizing its Gravity Science experiment to explore Jupiter’s upper atmospheric composition, unlocking crucial insights into the planet’s shape and interior structure.