NASA’s Juno supplies high-definition perspectives of Europa’s icy shell

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Jupiter’s moon Europa used to be captured by way of the JunoCam tool aboard NASA’s Juno spacecraft throughout the project’s shut flyby on Sept. 29, 2022. The pictures display the fractures, ridges, and bands that crisscross the moon’s floor. Credit score: NASA/JPL-Caltech/SwRI/MSSS; Symbol processing: Björn Jónsson (CC BY 3.0)

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Pictures from the JunoCam visible-light digital camera aboard NASA’s Juno spacecraft helps the speculation that the icy crust on the north and south poles of Jupiter’s moon Europa isn’t the place it was. Any other high-resolution image of the icy moon, by way of the spacecraft’s Stellar Reference Unit (SRU), unearths indicators of imaginable plume job and a space of ice shell disruption the place brine could have lately bubbled to the skin.

The JunoCam effects lately seemed within the Planetary Science Magazine and the SRU leads to the magazine JGR Planets.
On Sept. 29, 2022, Juno made its closest flyby of Europa, coming inside of 220 miles (355 kilometers) of the moon’s frozen floor. The 4 footage taken by way of JunoCam and one by way of the SRU are the primary high-resolution photographs of Europa since Galileo’s remaining flyby in 2000.
True polar wander
Juno’s floor monitor over Europa allowed imaging close to the moon’s equator. When inspecting the knowledge, the JunoCam staff discovered that along side the anticipated ice blocks, partitions, scarps, ridges, and troughs, the digital camera additionally captured irregularly disbursed steep-walled depressions 12 to 31 miles (20 to 50 kilometers) huge. They resemble massive ovoid pits up to now present in imagery from different places of Europa.

This black and white symbol of Europa’s floor used to be taken by way of the Stellar Reference Unit aboard NASA’s Juno spacecraft durring the Sept. 29, 2022 flyby. The chaos characteristic names “The Platypus” is noticed within the decrease proper nook. Credit score: NASA/JPL-Caltech/SwRI

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An enormous ocean is believed to are living under Europa’s icy external, and those floor options had been related to “true polar wander,” a principle that Europa’s outer ice shell is basically free-floating and strikes.
“True polar wander happens if Europa’s icy shell is decoupled from its rocky internal, leading to excessive tension ranges at the shell, which result in predictable fracture patterns,” mentioned Sweet Hansen, a Juno co-investigator who leads making plans for JunoCam on the Planetary Science Institute in Tucson, Arizona. “That is the primary time that those fracture patterns had been mapped within the southern hemisphere, suggesting that true polar wander’s impact on Europa’s floor geology is extra in depth than up to now recognized.”

The high-resolution JunoCam imagery has additionally been used to reclassify a previously outstanding floor characteristic from the Europa map.
“Crater Gwern is not more,” mentioned Hansen. “What used to be as soon as considered a 13-mile-wide have an effect on crater—one in every of Europa’s few documented have an effect on craters—Gwern used to be published in JunoCam knowledge to be a suite of intersecting ridges that created an oval shadow.”

This annotated symbol of Europa’s floor from Juno’s SRU presentations the positioning of a double ridge working east-west (blue field) with imaginable plume stains and the chaos characteristic the staff calls “the Platypus” (orange field). Those options trace at present floor job and the presence of subsurface liquid water at the icy Jovian moon. Credit score: NASA/JPL-Caltech/SwRI

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The Platypus
Even if all 5 Europa photographs from Juno are high-resolution, the picture from the spacecraft’s black-and-white SRU gives probably the most element. Designed to discover dim stars for navigation functions, the SRU is delicate to low gentle. To steer clear of over-illumination within the symbol, the staff used the digital camera to snap the nightside of Europa whilst it used to be lit simplest by way of daylight scattered off Jupiter (a phenomenon referred to as “Jupiter-shine”).
This leading edge way to imaging allowed advanced floor options to face out, revealing intricate networks of cross-cutting ridges and darkish stains from attainable plumes of water vapor. One intriguing characteristic, which covers a space 23 miles by way of 42 miles (37 kilometers by way of 67 kilometers), used to be nicknamed by way of the staff “the Platypus” on account of its form.
Characterised by way of chaotic terrain with hummocks, outstanding ridges, and darkish reddish-brown subject matter, the Platypus is the youngest characteristic in its community. Its northern “torso” and southern “invoice”—hooked up by way of a fractured “neck” formation—interrupt the encompassing terrain with a lumpy matrix subject matter containing a large number of ice blocks which are 0.6 to 4.3 miles (1 to 7 kilometers) huge. Ridge formations cave in into the characteristic on the edges of the Platypus.

For the Juno staff, those formations beef up the concept Europa’s ice shell can provide manner in places the place wallet of briny water from the subsurface ocean are reward underneath the skin.
About 31 miles (50 kilometers) north of the Platypus is a suite of double ridges flanked by way of darkish stains very similar to options discovered in different places on Europa that scientists have hypothesized to be cryovolcanic plume deposits.
“Those options trace at present-day floor job and the presence of subsurface liquid water on Europa,” mentioned Heidi Becker, lead co-investigator for the SRU at NASA’s Jet Propulsion Laboratory in Southern California, which additionally manages the project. “The SRU’s symbol is a fine quality baseline for particular puts NASA’s Europa Clipper project and ESA’s (Eu House Company’s) Juice missions can goal to seek for indicators of trade and brine.”
Europa Clipper’s focal point is on Europa—together with investigating whether or not the icy moon will have prerequisites appropriate for existence. It’s scheduled to release at the fall of 2024 and arrive at Jupiter in 2030. Juice (Jupiter Icy Moons Explorer) introduced on April 14, 2023. The ESA project will achieve Jupiter in July 2031 to review many objectives (Jupiter’s 3 massive icy moons, in addition to fiery Io and smaller moons, along side the planet’s setting, magnetosphere, and rings) with a unique focal point on Ganymede.
Juno achieved its 61st shut flyby of Jupiter on Would possibly 12. Its 62nd flyby of the gasoline large, scheduled for June 13, contains an Io flyby at an altitude of about 18,200 miles (29,300 kilometers).

Additional info:
C. J. Hansen et al, Juno’s JunoCam Pictures of Europa, The Planetary Science Magazine (2024). DOI: 10.3847/PSJ/ad24f4
Heidi N. Becker et al, A Advanced Area of Europa’s Floor With Hints of Fresh Job Published by way of Juno’s Stellar Reference Unit, Magazine of Geophysical Analysis: Planets (2023). DOI: 10.1029/2023JE008105

Magazine knowledge:
Magazine of Geophysical Analysis

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The Planetary Science Magazine