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Imagery from the solar-powered spacecraft shows some intriguing features on the ice-encased Jovian moon.<\/em><\/p>\n Images from the JunoCam visible-light camera aboard NASA\u2019s Juno spacecraft supports the theory that the icy crust at the north and south poles of Jupiter\u2019s moon Europa is not where it used to be. Another high-resolution picture of the icy moon, by the spacecraft\u2019s Stellar Reference Unit (SRU), reveals signs of possible plume activity and an area of ice shell disruption where brine may have recently bubbled to the surface.<\/p>\n The JunoCam results recently appeared in the Planetary Science Journal and the SRU results in the journal JGR Planets.<\/p>\n On Sept. 29, 2022, Juno made its closest flyby of Europa, coming within 220 miles (355 kilometers) of the moon\u2019s frozen surface. The four pictures taken by JunoCam and one by the SRU are the first high-resolution images of Europa since Galileo\u2019s last flyby in 2000.<\/p>\n Juno\u2019s ground track over Europa allowed imaging near the moon\u2019s equator. When analyzing the data, the JunoCam team found that along with the expected ice blocks, walls, scarps, ridges, and troughs, the camera also captured irregularly distributed steep-walled depressions 12 to 31 miles (20 to 50 kilometers) wide. They resemble large ovoid pits previously found in imagery from other locations of Europa.<\/p>\n A giant ocean is thought to reside below Europa\u2019s icy exterior, and these surface features have been associated with \u201ctrue polar wander,\u201d a theory that Europa\u2019s outer ice shell is essentially free-floating and moves.<\/p>\n \u201cTrue polar wander occurs if Europa\u2019s icy shell is decoupled from its rocky interior, resulting in high stress levels on the shell, which lead to predictable fracture patterns,\u201d said Candy Hansen, a Juno co-investigator who leads planning for JunoCam at the Planetary Science Institute in Tucson, Arizona. \u201cThis is the first time that these fracture patterns have been mapped in the southern hemisphere, suggesting that true polar wander\u2019s effect on Europa\u2019s surface geology is more extensive than previously identified.\u201d<\/p>\n The high-resolution JunoCam imagery has also been used to reclassify a formerly prominent surface feature from the Europa map.<\/p>\n \u201cCrater Gwern is no more,\u201d said Hansen. \u201cWhat was once thought to be a 13-mile-wide impact crater \u2014 one of Europa\u2019s few documented impact craters \u2014 Gwern was revealed in JunoCam data to be a set of intersecting ridges that created an oval shadow.\u201d<\/p>\n Although all five Europa images from Juno are high-resolution, the image from the spacecraft\u2019s black-and-white SRU offers the most detail. Designed to detect dim stars for navigation purposes, the SRU is sensitive to low light. To avoid over-illumination in the image, the team used the camera to snap the nightside of Europa while it was lit only by sunlight scattered off Jupiter (a phenomenon called \u201cJupiter-shine\u201d).<\/p>\n This innovative approach to imaging allowed complex surface features to stand out, revealing intricate networks of cross-cutting ridges and dark stains from potential plumes of water vapor. One intriguing feature, which covers an area 23 miles by 42 miles (37 kilometers by 67 kilometers), was nicknamed by the team \u201cthe Platypus\u201d because of its shape.<\/p>\n Characterized by chaotic terrain with hummocks, prominent ridges, and dark reddish-brown material, the Platypus is the youngest feature in its neighborhood. Its northern \u201ctorso\u201d and southern \u201cbill\u201d \u2014 connected by a fractured \u201cneck\u201d formation \u2014 interrupt the surrounding terrain with a lumpy matrix material containing numerous ice blocks that are 0.6 to 4.3 miles (1 to 7 kilometers) wide. Ridge formations collapse into the feature at the edges of the Platypus.<\/p>\n For the Juno team, these formations support the idea that Europa\u2019s ice shell may give way in locations where pockets of briny water from the subsurface ocean are present beneath the surface.<\/p>\n About 31 miles (50 kilometers) north of the Platypus is a set of double ridges flanked by dark stains similar to features found elsewhere on Europa that scientists have hypothesized to be cryovolcanic plume deposits.<\/p>\n \u201cThese features hint at present-day surface activity and the presence of subsurface liquid water on Europa,\u201d said Heidi Becker, lead co-investigator for the SRU at NASA\u2019s Jet Propulsion Laboratory in Southern California, which also manages the mission. \u201cThe SRU\u2019s image is a high-quality baseline for specific places NASA\u2019s Europa Clipper mission and ESA\u2019s (European Space Agency\u2019s) Juice missions can target to search for signs of change and brine.\u201d<\/p>\n Europa Clipper\u2019s focus is on Europa \u2014 including investigating whether the icy moon could have conditions suitable for life. It is scheduled to launch on the fall of 2024 and arrive at Jupiter in 2030. Juice (Jupiter Icy Moons Explorer) launched on April 14, 2023. The ESA mission will reach Jupiter in July 2031 to study many targets (Jupiter\u2019s three large icy moons, as well as fiery Io and smaller moons, along with the planet\u2019s atmosphere, magnetosphere, and rings) with a special focus on Ganymede.<\/p>\n Juno executed its 61st close flyby of Jupiter on May 12. Its 62nd flyby of the gas giant, scheduled for June 13, includes an Io flyby at an altitude of about 18,200 miles (29,300 kilometers).<\/p>\n JPL, a division of Caltech in Pasadena, California, manages the Juno mission for the principal investigator, Scott 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. The Italian Space Agency (ASI) funded the Jovian InfraRed Auroral Mapper. Lockheed Martin Space in Denver built and operates the spacecraft.<\/p>\n More information about Juno is available at:<\/p>\n <\/strong><\/p>\n DC Agle Karen Fox \/ Charles Blue Deb Schmid 2024-066<\/p>\n<\/div>\n
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-9011
agle@jpl.nasa.gov<\/p>\n
NASA Headquarters, Washington
301-286-6284 \/ 202-802-5345
karen.c.fox@nasa.gov\u00a0\/\u00a0charles.e.blue@nasa.gov<\/p>\n
Southwest Research Institute, San Antonio
210-522-2254
dschmid@swri.org<\/p>\n