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How Europa’s Thick Ice May Obstruct the Hunt for Ocean Life

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Europa’s Ice: A Thick Shell Over a Salty Ocean

Claudio Caridi / Alamy

Europa, one of Jupiter’s intriguing moons, features a liquid ocean possibly encased beneath a thick layer of ice, estimated to be six times the depth of Antarctica’s icy crust, complicating our efforts to detect any potential lifeforms.

This moon is a leading candidate in the search for extraterrestrial life, primarily due to its significant volume of liquid water.

Previously, estimates regarding the thickness of Europa’s ice have varied dramatically—ranging from under 10 kilometers to nearly 50 kilometers. Researchers initially believed certain defects in the ice might permit nutrient exchange between the surface and the ocean below.

Now, a research team, led by Stephen Levin from the California Institute of Technology, has analyzed data collected by the Juno spacecraft, which has been orbiting Jupiter since 2016.

On September 29, 2022, Juno came within 360 kilometers of Europa, utilizing its microwave radiometer to scan the surface and perform the first direct measurements of the ice layer. Levin noted that this instrument assessed the heat emitted by Europa’s icy exterior, enabling the measurement of ice temperatures at various depths and detecting temperature fluctuations resulting from imperfections in the ice sheet.

The researchers estimate that the most accurate thickness of the ice sheet is approximately 29 kilometers, aligning with the higher range of previous estimates while presenting a possible thickness that could range from 19 kilometers to 39 kilometers.

Crucially, their findings indicate that the fissures, pores, and other imperfections likely extend only a few hundred meters beneath the surface, with pore diameters measuring only a few centimeters.

“This indicates that the observed defects in the microwave radiometers are insufficiently deep or expansive to facilitate significant nutrient transport between the ocean and the surface,” asserts Levin.

Nonetheless, this does not diminish the potential for life on Europa. Levin further explains, “Though the observed pores and cracks are too minute and shallow to transport nutrients, alternative transportation mechanisms may exist.”

There may also be unexplored regions of the moon where conditions differ, he adds.

Researchers including Ben Montet from the University of New South Wales in Sydney, express concerns that the ice thickness could hinder life’s search. “While this protection may sustain life for extended durations, it complicates our ability to penetrate the ice and study the ocean beneath,” he notes.

He argues that life could exist without a direct link between Europa’s surface and its subterranean ocean, though such a connection would enhance the chances of discovering life. Helen Maynard-Casley of the Australian Nuclear Science and Technology Agency emphasizes that without that transport link, “you’re essentially confined to whatever was in the ocean initially.”

NASA has plans to launch the Europa Clipper spacecraft in 2024, aiming to embark on its mission to Jupiter’s moons in 2030. This spacecraft is expected to provide clearer insights into Europa’s icy layer, according to Maynard-Casley.

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Source: www.newscientist.com

Orcas and Dolphins Form ‘Friendship’ to Hunt Salmon Cooperatively

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Dolphin approaches killer whale, captured by the killer whale’s camera

University of British Columbia (A.Trites), Dalhousie University (S. Fortune), Hakai Institute (K. Holmes), Leibniz Zoo and Wildlife Institute (X. Cheng)

Killer whales and dolphins collaborate to catch salmon in the North Pacific Ocean, revealing new insights into the intricate social dynamics of marine mammals.

Using video cameras and sensors attached to nine killer whales, researchers observed four of them diving alongside a large group of white-tailed dolphins towards Chinook salmon hiding in deep waters off northern Vancouver Island. An additional three whales were tracked via drone. The killer whales consumed the salmon, leaving behind scraps that the dolphins scavenged.

“They collaborated to locate food,” states Sarah Fortune from Dalhousie University, Canada. “One might anthropomorphize this scenario and suggest that they’re hunting friends.”

Chinook salmon, or king salmon, can exceed a meter in length, making them often too large for dolphins to consume.

However, the whales off northern Vancouver Island are known for their hearty appetites, frequently tearing fish apart to share with their pod, which leaves behind blood, scales, and remnants for dolphins to eat. Researchers propose that dolphins assist whales in locating salmon.

In the video, six out of twelve whales directed their attention toward the dolphins, totaling 102 interactions. The four whales dove with the dolphins to depths of 60 meters, where it becomes dark and salmon can conceal themselves among rocks and crevices.

Though both species emitted clicking and buzzing sounds, data from the sensors indicated that the whales often reduced their echolocation activity, likely to “eavesdrop” on the dolphins. Since echolocation operates like a focused spotlight, having numerous dolphins scanning the waters could enhance the whales’ chances of finding fish, according to Fortune.

“It’s akin to turning on the high beams of a vehicle; the sound serves as the light,” she elaborates.

Prior to this, scientists have noted cooperation among various species, such as fish guiding octopuses to crustaceans and nectar birds leading humans to bee colonies. However, documented interactions between killer whales and other species have often involved predatory behaviors.

Recently, killer whales were reported to have rammed and sunk six sailing vessels around the Iberian Peninsula, suggesting they may be engaging with boats rather than attacking. They are playing with them.

Brittany Visona Kelly from the global conservation group Ocean Wise asserts that the dolphins in this study are not aiding the whales but scavenging leftovers. In a study she and her colleagues, including Lance Barrett-Leonard, revealed drone footage showing whales seemingly ignoring the dolphins, playing with them, and occasionally charging at them. Their findings suggest that dolphins primarily seek refuge from a specific group of mammal-eating killer whales, known as big killer whales, which tend to avoid resident orcas.

“We found no clear evidence that these interactions benefit killer whales,” Visona-Kelly concluded.

The study reported last month indicated that between 30 to 40 white-tailed dolphins encircled an emaciated killer whale known to researchers as “I76,” who remained submerged and did not reemerge. This suggests that the dolphins may have “exhausted I76, making it impossible for him to surface.”

Luke Rendell from the University of St. Andrews in the UK emphasized that the new research provides compelling evidence of cooperation, whether the whales are interpreting dolphin echolocation or drawn to the commotion as a potential indicator of fish.

“These animals are intelligent and possess adaptable behaviors,” he notes. “We witness a range of interactions between killer whales and dolphins, from the former preying on each other to playful interactions and collaborative efforts.”

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  • whale and dolphin/
  • animal behavior

Source: www.newscientist.com

Scientists use innovative method to hunt for signs of extraterrestrial technology

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techno signature Any measurable property that could provide evidence of extraterrestrial technology. The Search for Extraterrestrial Intelligence (SETI) is a branch of astrobiology that focuses on the discovery of technosignatures, which provide evidence of extraterrestrial intelligence. Traditionally, targeted wireless surveys have been the mainstay of his SETI research, and many of his ongoing SETI projects are still conducted in the radio band. SETI Ellipsoid, a newly proposed technology, suggests that an extraterrestrial civilization observing a galactic-scale event such as supernova SN 1987A could use it as a point to broadcast a synchronization signal indicating its presence. This is a strategy for selecting techno signature candidates based on the assumption that .

Gaia Early Data Release 3, using Cabrales' improved star 3D positions other. identified 32 SN 1987A SETI ellipsoidal targets with uncertainties better than 0.5 light-years within the TESS continuum. Image credits: ALMA/ESO/NAOJ/NRAO/Alexandra Angelich, NRAO/AUI/NSF.

Barbara Cabrales, Ph.D., of the SETI Institute and the Berkeley SETI Research Center at the University of California, Berkeley, and her colleagues demonstrate that the SETI ellipsoid method leverages continuous, wide-field surveys of the sky and demonstrates its ability to detect potential technosignatures. We have shown that it can be significantly improved.

By using up to a year of observations to correct for uncertainties in the estimated time of arrival of such signals, we implement the SETI ellipsoid strategy in an innovative way using state-of-the-art technology.

“The new survey of the sky provides a groundbreaking opportunity to search for technosignatures in concert with supernovae,” Dr. Cabrales said.

“Typical timing uncertainty takes months, so we want to cover the bases by finding well-documented goals over about a year.”

“In addition to that, it's important to make as many observations as possible about each target of interest, so you can see what looks like normal behavior and what looks like potential techno-signatures.” You will be able to judge.”

In examining data from the Continuous Display Zone of NASA's TESS mission, which covers 5% of all TESS data during the first three years of the mission, the authors leveraged advanced 3D position data from Gaia Early Data Release 3. Did.

This analysis identified 32 major targets within the SETI ellipsoid in the southern part of the TESS continuum, with all uncertainties adjusted to better than 0.5 light-years.

Although initial inspection of TESS light curves during ellipsoid-crossing events did not find any anomalies, the foundation laid by this effort lends itself to other investigations, a broader range of targets, and a variety of potential signal types. Paving the way for expansion into research.

Applying SETI Ellipsoid technology to scour large archival databases represents a breakthrough in the search for technosignatures.

This study demonstrates the feasibility of leveraging Gaia's highly accurate distance estimates and cross-matching these distances with other time-domain surveys such as TESS to enhance monitoring and anomaly detection capabilities in SETI research. doing.

Combining the SETI Ellipsoid method with Gaia's distance measurements provides a robust and adaptable framework for future SETI searches.

Astronomers can apply it retrospectively to sift through archived data for potential signals, proactively select targets, and schedule future monitoring campaigns.

“The SETI Ellipsoid method, in collaboration with Gaia distances, provides an easy and flexible method for SETI searches that can be adapted to suit a variety of current surveys and source events,” the researchers said. I am.

“This can not only be applied retrospectively to look for signals in archived data, but also propagated in time to select targets and schedule surveillance campaigns.”

Their paper will appear in astronomy magazine.

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Barbara Cabrales other. 2024. Find the SN 1987A SETI ellipsoid using TESS. A.J. 167, 101; doi: 10.3847/1538-3881/ad2064

Source: www.sci.news