When NASA’s Juno spacecraft carried out its closest strategy to Jupiter‘s moon Europa in September 2022, it captured proof not just for pockets of briny water linked to the world’s deep subsurface ocean, but additionally for potential scars fashioned by towering plumes of water vapor — and it caught that proof on digicam
The vast majority of imagery from the Juno mission is taken by an instrument known as JunoCam, which scientists revealed was in a position to take 4 high-resolution photos of Europa’s floor because it raced previous the icy moon at an altitude of simply 355 kilometers (220 miles). The spacecraft additionally employed its Stellar Reference Unit (SRU), which is often used for imaging faint stars, to assist Juno navigate. On this event, nonetheless, the SRU’s low-light capabilities had been tailored to take one picture of the night-side of Europa. That is the facet that shines solely with gentle mirrored off the cloud-tops of Jupiter — we name it “Jupiter-shine.”
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The SRU discovered an uncommon function that has been nicknamed “the Platypus” due to its form. Formally talking, it’s what’s generally known as chaos terrain — a jumble of ice blocks, ridges, hummocks and ruddy-brown stains. Chaos terrain has been imaged on the floor of Europa because the days of the Voyager missions, and planetary scientists suspect that such areas could also be areas the place briny liquid seeps to the floor, partially melting the icy crust.
The platypus is big, spanning 37 kilometers by 67 kilometers (23 miles by 42 miles). As a result of Europa’s icy floor tends to clean itself out over geologically quick time spans, erasing floor options equivalent to craters, then the Platypus have to be one of many youngest options on the Jovian moon.
“These options trace at present-day floor exercise and the presence of subsurface liquid water on Europa,” mentioned Heidi Becker, who’s the SRU’s lead co-investigator at NASA’s Jet Propulsion Laboratory, in a statement. Becker goes on to counsel that the Platypus shall be a major goal for each NASA’s Europa Clipper mission, which launches later this 12 months, and the European JUICE mission, which is already on its approach to Jupiter.
Fifty kilometers (31 miles) north of the Platypus are doubtlessly much more thrilling options: a set of double ridges flanked by darkish stains on the floor. Such options have beforehand been seen elsewhere on Europa, and are believed to be an origin level for plumes of water vapor that spurt up into house, reaching heights of 200 kilometers (120 miles).
The elusive plumes have been considerably controversial ever because the Hubble House Telescope first caught sight of them in 2012. Nevertheless, not like Saturn‘s moon Enceladus, the place plumes are a predictable and customary prevalence, Europa’s plumes have been considerably spotty, main some researchers to doubt plumes exist in any respect on Europa The invention of trenches, considerably analogous to the tiger stripes on Enceladus— the factors of origin for the world’s plumes — will present Europa Clipper and JUICE with areas to focus on of their seek for the plumes on Europa as nicely.
Nevertheless, Juno has additionally discovered highly effective proof that these options, and the floor as an entire, are shifting beneath Juno’s metaphorical ft. Scientists name it “true polar wander,” which implies the geographic places of the poles have meandered throughout the moon because the icy crust successfully floats on the subsurface international ocean.
“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,” mentioned Sweet Hansen, who’s a Juno co-investigator on the Planetary Science Institute in Arizona.
Juno imaged these fracture patterns within the type of steep-walled, irregularly formed depressions between 20 kilometers and 50 kilometers in measurement (12 miles to 31 miles).
“That is the primary time that these fracture patterns have been mapped in [Europa’s] southern hemisphere, suggesting that true polar wander’s impact on Europa’s floor geology is extra intensive than beforehand recognized,” mentioned Hansen.
The outcomes of JunoCam’s photos of Europa through the flyby had been revealed in March in The Planetary Science Journal, and the SRU outcomes had been revealed in December 2023 within the journal JGR Planets.
