![\"\"](\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/12\/1-pia26234-io-flyby-image2.jpg?w=1975\")
<\/figure>The orbiter has performed 56 flybys of Jupiter and documented close encounters with three of the gas giant\u2019s four largest moons.<\/em><\/p>\n NASA\u2019s Juno spacecraft will on Tuesday, Dec. 30, make the closest flyby of Jupiter\u2019s moon Io that any spacecraft has made in over 20 years<\/a>. Coming within roughly 930 miles (1,500 kilometers) from the surface of the most volcanic world in our solar system, the pass is expected to allow Juno instruments to generate a firehose of data.<\/p>\n \u201cBy combining data from this flyby with our previous observations, the Juno science team is studying how Io\u2019s volcanoes vary,\u201d said Juno\u2019s principal investigator, Scott Bolton of the Southwest Research Institute in San Antonio, Texas. \u201cWe are looking for how often they erupt, how bright and hot they are, how the shape of the lava flow changes, and how Io\u2019s activity is connected to the flow of charged particles in Jupiter\u2019s magnetosphere.\u201d<\/p>\n A second ultra-close flyby of Io is scheduled for Feb. 3, 2024, in which Juno will again come within about 930 miles (1,500 kilometers) of the surface.<\/p>\n The spacecraft has been monitoring Io\u2019s 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\u2019s north and south poles. The spacecraft has also performed close flybys of Jupiter\u2019s icy moons Ganymede and Europa.<\/p>\n \u201cWith our pair of close flybys in December and February, Juno will investigate the source of Io\u2019s 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,\u201d said Bolton.<\/p>\n Now in the third year of its extended mission<\/a> to investigate the origin of Jupiter, the solar-powered spacecraft will also explore the ring system where some of the gas giant\u2019s inner moons reside.<\/p>\n All three cameras aboard Juno will be active during the Io flyby. The Jovian Infrared Auroral Mapper (JIRAM<\/em>), which takes images in infrared, will be collecting the heat signatures emitted by volcanoes and calderas covering the moon\u2019s surface. The mission\u2019s 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 color images.<\/p>\n JunoCam was included on the spacecraft for the public\u2019s engagement and was designed to operate for up to eight flybys of Jupiter. The upcoming flyby of Io will be Juno\u2019s 57th orbit around Jupiter, where the spacecraft and cameras have endured one of the solar system\u2019s most punishing radiation environments.<\/p>\n \u201cThe cumulative effects of all that radiation has begun to show on JunoCam over the last few orbits,\u201d said Ed Hirst, project manager of Juno at NASA\u2019s Jet Propulsion Laboratory in Southern California. \u201cPictures from the last flyby show a reduction in the imager\u2019s dynamic range and the appearance of \u2018striping\u2019 noise. Our engineering team has been working on solutions to alleviate the radiation damage and to keep the imager going.\u201d<\/p>\n After several months of study and assessment, the Juno team adjusted the spacecraft\u2019s planned future trajectory to add seven new distant Io flybys (for a total of 18) to the extended mission plan. After the close Io pass on Feb. 3, the spacecraft will fly by Io every other orbit, with each orbit growing progressively more distant: The first will be at an altitude of about 10,250 miles (16,500 kilometers) above Io, and the last will be at about 71,450 miles (115,000 kilometers).<\/p>\n The gravitational pull of Io on Juno during the Dec. 30 flyby will reduce the spacecraft\u2019s orbit around Jupiter from 38 days to 35 days. Juno\u2019s orbit will drop to 33 days after the Feb. 3 flyby.<\/p>\n After that, Juno\u2019s new trajectory will result in Jupiter blocking the Sun from the spacecraft for about five minutes at the time when the orbiter is at its closest to the planet, a period called perijove. Although this will be the first time the solar-powered spacecraft has encountered darkness since its flyby of Earth in October 2013, the duration will be too short to affect its overall operation. With the exception of the Feb. 3 perijove, the spacecraft will encounter solar eclipses like this during every close flyby of Jupiter from now on through the remainder of its extended mission, which ends in late 2025.<\/p>\n Starting in April 2024, the spacecraft will carry out a series of occultation experiments that use Juno\u2019s Gravity Science experiment<\/a> to probe Jupiter\u2019s upper atmospheric makeup, which provides key information on the planet\u2019s shape and interior structure.<\/p>\n JPL, a division of Caltech in Pasadena, California, manages the Juno mission for the principal investigator, Scott J. Bolton, of the Southwest Research Institute in San Antonio. Juno is part of NASA\u2019s New Frontiers Program, which is managed at NASA\u2019s Marshall Space Flight Center in Huntsville, Alabama, for the agency\u2019s Science Mission Directorate in Washington. Lockheed Martin Space in Denver built and operates the spacecraft.<\/p>\n More information about Juno is available at:<\/p>\n https:\/\/www.nasa.gov\/juno<\/strong><\/a><\/p>\n DC Agle Karen Fox \/ Alana Johnson Deb Schmid 2023-188<\/p>\n![\"This](\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/12\/e1-pia26235-fig-a-io-plume-anotated.jpg?w=1091\")
<\/figure>Picture This<\/strong><\/h3>\n
More Io, Please<\/strong><\/h3>\n
More About the Mission<\/strong><\/h3>\n
News Media Contacts<\/strong><\/h3>\n
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-9011
agle@jpl.nasa.gov<\/a><\/p>\n
NASA Headquarters, Washington
301-286-6284 \/ 202-358-1501
karen.c.fox@nasa.gov<\/a> \/ alana.r.johnson@nasa.gov<\/a><\/p>\n
Southwest Research Institute, San Antonio
210-522-2254
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