- NASA’s Juno mission has supplied photos and new particulars about Jupiter’s ocean moon Europa.
- The findings counsel the moon’s ice shell floats on high of the ocean and might transfer round in a course of referred to as true polar wander.
- The pictures additionally reveal extra proof for earlier water vapor plumes that left cryovolcanic deposits on Europa’s floor and locations the place watery brines might have trickled as much as the floor.
House followers are eagerly awaiting the upcoming Europa Clipper mission, which is able to present our closest look but at Europa, Jupiter’s intriguing ocean moon. It’ll launch this coming fall. Within the meantime, scientists have been analyzing some new high-definition photos from the Juno spacecraft, which has been orbiting Jupiter since 2016. NASA said on Might 15, 2024, that Juno didn’t detect any lively plumes of liquid on Europa, like these we see on Saturn’s moon Enceladus. However the newly-released photos do assist the speculation that Europa’s crust is free-floating on an ocean under. They usually present indicators of deposits from ice volcanoes (cryovolcanoes) on the floor from attainable earlier water vapor plumes. Plus there’s a “disappearing crater” and an uncommon “platypus”-shaped function.
Juno obtained these photos on September 29, 2022. They’re the closest ones but of Europa. The peer-reviewed outcomes are introduced in two new papers, one in The Planetary Science Journal (March 21, 2024) and the other in JGR Planets (December 22, 2023).
The JunoCam instrument took 4 of the photographs and the Stellar Reference Unit (SRU) obtained one picture. Juno got here inside 220 miles (355 kilometers) of the moon’s frozen, icy floor.
Free-floating ice shell
One massive discovering is that the photographs assist the speculation that Europa has skilled true polar wander. The idea states that Europa’s ice crust is free-floating on high of the ocean under. Which means the ice shell can transfer. The pictures confirmed irregularly distributed steep-walled depressions 12 to 31 miles (20 to 50 kilometers) broad. The depressions resemble massive ovoid pits beforehand that scientists have seen in imagery from different areas on Europa.
Candy Hansen is the lead creator of the primary paper, on the Planetary Science Institute in Tucson, Arizona. She said:
True polar wander happens if Europa’s icy shell is decoupled from its rocky inside, leading to excessive stress ranges on the shell, which result in predictable fracture patterns. That is the primary time that these fracture patterns have been mapped within the southern hemisphere, suggesting that true polar wander’s impact on Europa’s floor geology is extra in depth than beforehand recognized.
Disappearing crater
Gwern crater was regarded as one of many few craters seen on Europa’s floor, about 13 miles (21 km) throughout. However the brand new Juno photos revealed it to be an phantasm. As Hansen defined:
Crater Gwern isn’t any extra. What was as soon as regarded as a 13-mile-wide impression crater – certainly one of Europa’s few documented impression craters – Gwern was revealed in JunoCam knowledge to be a set of intersecting ridges that created an oval shadow.
Consequently, the variety of recognized craters bigger than one km on Europa is now 40 as an alternative of 41.
The Platypus
One of many intriguing options seen within the photos is nicknamed the Platypus, given its form. It’s 23 miles (37 km) broad by 42 miles (68 km) lengthy and geologically youthful than the encompassing terrain. It’s an space of chaos terrain, that includes hummocks, ridges, and darkish reddish-brown materials inside it. The “torso” and “invoice” are linked by a “neck” that’s fractured. There are additionally many ice blocks starting from 0.6 to 4.3 miles (1 to 7 km) broad.
The researchers mentioned that this can be an space the place briny water from under has reached the floor. The paper stated:
Though its topographic context is just not properly understood as a result of absence of stereo for this area, our morphological findings from shape-from-shading and visible interpretation are per a number of predictions made by the soften lens mannequin for chaos formation. That mannequin predicts the presence of subsurface liquid, and ongoing formation exercise in options the place floor ice subsides and ice blocks float under the encompassing terrain.
Plume deposits in photos of Europa?
Scientists have beforehand seen hints of water vapor plumes on Europa, much like these on Saturn’s moon Enceladus. They appear to be smaller and fewer frequent, nevertheless. One other function within the Juno photos helps the plume speculation. It’s a set of double ridges flanked by darkish stains, about 31 miles (50 km) north of the Platypus. It is a perfect goal for NASA’s upcoming Europa Clipper mission and the ESA’s Jupiter Icy Moons (Juice) mission. Heidi Becker, lead co-investigator for the SRU at NASA’s Jet Propulsion Laboratory in Southern California, mentioned:
The SRU’s picture is a high-quality baseline for particular locations NASA’s Europa Clipper mission and ESA’s (European House Company’s) Juice mission can goal to seek for indicators of change and brine.
Juno didn’t detect any indicators of present plume exercise throughout its observations. That doesn’t imply there aren’t any eruptions occurring in any respect although, because the paper noted:
Nonetheless, an eruption must happen at simply the fitting longitude (limb or terminator) and simply the fitting time when Juno flew by, so the chance of a detection was by no means very excessive
Europa Clipper and Juice
Europa Clipper, because the title implies, will give attention to Europa, making quite a few shut flybys of the moon. It is going to reveal extra particulars about each Europa’s floor and subsurface ocean. It is going to launch later this 12 months and arrive in 2030.
ESA’s Jupiter Icy Moons Explorer (Juice) is already on its solution to Jupiter, launched on April 14, 2023. It is going to attain Jupiter in July 2031. Not like Europa Clipper, it would examine Jupiter, its rings and quite a few moons, with a give attention to the most important moon, Ganymede.
Juno has already performed 61 shut flybys of Jupiter itself, the newest being on Might 12, 2024. The subsequent one will probably be on June 13, the place the spacecraft may even come to inside 18,200 miles (29,300 km) of the volcanic moon Io. Launched on August 5, 2011, Juno has been exploring Jupiter and its moons since 2016. Its main mission is to review the large planet’s environment and inside, but it surely does typically conduct flybys of some the bigger moons as properly.
Backside line: NASA has launched some photos of Europa, the ocean moon of Jupiter. They supply new clues concerning the moon’s ice shell and different intriguing floor options.
Source: Juno’s JunoCam Images of Europa
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