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Methane in the plumes of Saturn's moon Enceladus: Possible signs of life? – Phys.org

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This artist’s impression depicts NASA’s Cassini spacecraft flying through a plume of presumed water erupting from the surface of Saturn’s moon Enceladus. Credit: NASA

An unknown methane-producing process is likely at work in the hidden ocean beneath the icy shell of Saturn’s moon Enceladus, suggests a new study published in Nature Astronomy by scientists at the University of Arizona and Paris Sciences & Lettres University.

Giant water plumes erupting from Enceladus have long fascinated scientists and the public alike, inspiring research and speculation about the vast ocean that is believed to be sandwiched between the moon’s rocky core and its icy shell. Flying through the plumes and sampling their , the Cassini spacecraft detected a relatively high concentration of certain molecules associated with on the bottom of Earth’s oceans, specifically dihydrogen, and carbon dioxide. The amount of methane found in the plumes was particularly unexpected.

“We wanted to know: Could Earthlike microbes that ‘eat’ the dihydrogen and produce methane explain the surprisingly large amount of methane detected by Cassini?” said Regis Ferriere, an associate professor in the University of Arizona Department of Ecology and Evolutionary Biology and one of the study’s two lead authors. “Searching for such microbes, known as methanogens, at Enceladus’ seafloor would require extremely challenging deep-dive missions that are not in sight for several decades.”

Ferriere and his team took a different, easier route: They constructed mathematical models to calculate the probability that different processes, including biological methanogenesis, might explain the Cassini data.

The authors applied new mathematical models that combine geochemistry and microbial ecology to analyze Cassini plume data and model the possible processes that would best explain the observations. They conclude that Cassini’s data are consistent either with microbial hydrothermal vent activity, or with processes that don’t involve but are different from the ones known to occur on Earth.

On Earth, hydrothermal activity occurs when cold seawater seeps into the ocean floor, circulates through the underlying rock and passes close by a heat source, such as a magma chamber, before spewing out into the water again through hydrothermal vents. On Earth, methane can be produced through hydrothermal activity, but at a slow rate. Most of the production is due to microorganisms that harness the chemical disequilibrium of hydrothermally produced dihydrogen as a source of energy, and produce methane from carbon dioxide in a process called methanogenesis.

The team looked at Enceladus’ plume composition as the end result of several chemical and physical processes taking place in the moon’s interior. First, the researchers assessed what hydrothermal production of dihydrogen would best fit Cassini’s observations, and whether this production could provide enough “food” to sustain a population of Earthlike hydrogenotrophic methanogens. To do that, they developed a model for the population dynamics of a hypothetical hydrogenotrophic methanogen, whose thermal and energetic niche was modeled after known strains from Earth.

The authors then ran the model to see whether a given set of chemical conditions, such as the dihydrogen concentration in the hydrothermal fluid, and temperature would provide a suitable environment for these microbes to grow. They also looked at what effect a hypothetical microbe population would have on its environment—for example, on the escape rates of dihydrogen and methane in the plume.

Methane in the plumes of Saturn's moon Enceladus: Possible signs of life?
This cutaway view of Saturn’s moon Enceladus is an artist’s rendering that depicts possible hydrothermal activity that may be taking place on and under the seafloor of the moon’s subsurface ocean, based on results from NASA’s Cassini mission. Credit: NASA/JPL-Caltech

“In summary, not only could we evaluate whether Cassini’s observations are compatible with an environment habitable for life, but we could also make quantitative predictions about observations to be expected, should methanogenesis actually occur at Enceladus’ seafloor,” Ferriere explained.

The results suggest that even the highest possible estimate of abiotic methane production—or methane production without biological aid—based on known hydrothermal chemistry is far from sufficient to explain the methane concentration measured in the plumes. Adding biological methanogenesis to the mix, however, could produce enough methane to match Cassini’s observations.

“Obviously, we are not concluding that life exists in Enceladus’ ocean,” Ferriere said. “Rather, we wanted to understand how likely it would be that Enceladus’ hydrothermal vents could be habitable to Earthlike microorganisms. Very likely, the Cassini data tell us, according to our models.

“And biological methanogenesis appears to be compatible with the data. In other words, we can’t discard the ‘life hypothesis’ as highly improbable. To reject the life hypothesis, we need more data from future missions,” he added.

The authors hope their paper provides guidance for studies aimed at better understanding the observations made by Cassini and that it encourages research to elucidate the abiotic processes that could produce enough methane to explain the data.

For example, methane could come from the chemical breakdown of primordial organic matter that may be present in Enceladus’ core and that could be partially turned into dihydrogen, methane and carbon dioxide through the hydrothermal process. This hypothesis is very plausible if it turns out that Enceladus formed through the accretion of organic-rich material supplied by comets, Ferriere explained.

“It partly boils down to how probable we believe different hypotheses are to begin with,” he said. “For example, if we deem the probability of life in Enceladus to be extremely low, then such alternative abiotic mechanisms become much more likely, even if they are very alien compared to what we know here on Earth.”

According to the authors, a very promising advance of the paper lies in its methodology, as it is not limited to specific systems such as interior oceans of icy moons and paves the way to deal with chemical data from planets outside the solar system as they become available in the coming decades.


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Researchers study methane-rich plumes from Saturn’s icy moon Enceladus


More information:
Antonin Affholder et al, Bayesian analysis of Enceladus’s plume data to assess methanogenesis, Nature Astronomy (2021). DOI: 10.1038/s41550-021-01372-6

Citation:
Methane in the plumes of Saturn’s moon Enceladus: Possible signs of life? (2021, July 7)
retrieved 7 July 2021
from https://phys.org/news/2021-07-methane-plumes-saturn-moon-enceladus.html

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Facial Recognition—Now for Seals – Hakai Magazine

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Have you ever looked at a seal and thought, Is that the same seal I saw yesterday? Well, there could soon be an app for that based on new seal facial recognition technology. Known as SealNet, this seal face-finding system was developed by a team of undergraduate students from Colgate University in New York.

Taking inspiration from other technology adapted for recognizing primates and bears, Krista Ingram, a biologist at Colgate University, led the students in developing software that uses deep learning and a convolutional neural network to tell one seal face from another. SealNet is tailored to identify the harbor seal, a species with a penchant for posing on coasts in haulouts.

The team had to train their software to identify seal faces. “I give it a photograph, it finds the face, [and] clips it to a standard size,” says Ingram. But then she and her students would manually identify the nose, the mouth, and the center of the eyes.

For the project, team members snapped more than 2,000 pictures of seals around Casco Bay, Maine, during a two-year period. They tested the software using 406 different seals and found that SealNet could correctly identify the seals’ faces 85 percent of the time. The team has since expanded its database to include around 1,500 seal faces. As the number of seals logged in the database goes up, so too should the accuracy of the identification, Ingram says.

The developers of SealNet trained a neural network to tell harbor seals apart using photos of 406 different seals. Photo courtesy of Birenbaum et al.

As with all tech, however, SealNet is not infallible. The software saw seal faces in other body parts, vegetation, and even rocks. In one case, Ingram and her students did a double take at the uncanny resemblance between a rock and a seal face. “[The rock] did look like a seal face,” Ingram says. “The darker parts were about the same distance as the eyes … so you can understand why the software found a face.” Consequently, she says it’s always best to manually check that seal faces identified by the software belong to a real seal.

Like a weary seal hauling itself onto a beach for an involuntary photo shoot, the question of why this is all necessary raises itself. Ingram believes SealNet could be a useful, noninvasive tool for researchers.

Of the world’s pinnipeds—a group that includes seals, walruses, and sea lions—harbor seals are considered the most widely dispersed. Yet knowledge gaps do exist. Other techniques to track seals, such as tagging and aerial monitoring, have their limitations and can be highly invasive or expensive.

Ingram points to site fidelity as an aspect of seal behavior that SealNet could shed more light on. The team’s trials indicated that some harbor seals return to the same haulout sites year after year. Other seals, however, such as two animals the team nicknamed Clove and Petal, appeared at two different sites together. Increasing scientists’ understanding of how seals move around could strengthen arguments for protecting specific areas, says Anders Galatius, an ecologist at Aarhus University in Denmark who was not involved in the project.

Galatius, who is responsible for monitoring Denmark’s seal populations, says the software “shows a lot of promise.” If the identification rates are improved, it could be paired with another photo identification method that identifies seals by distinctive markings on their pelage, he says.

In the future, after further testing, Ingram hopes to develop an app based on SealNet. The app, she says, could possibly allow citizen scientists to contribute to logging seal faces. The program could also be adapted for other pinnipeds and possibly even for cetaceans.

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NASA launches nanosatellite in preparation for lunar 'Gateway' station – Yahoo News Canada

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The rocket carrying the Capstone satellite lifts off. (NASA)

Nasa has launched a tiny CubeSat this week to test and orbit which will soon be used by Gateway, a lunar space station.

It’s all part of the space agency’s plan to put a woman on the moon by 2025.

The Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment (Capstone) mission launched from New Zealand on Tuesday.

Jim Reuter, associate administrator for the Space Technology Mission Directorate, said: “Capstone is an example of how working with commercial partners is key for Nasa’s ambitious plans to explore the moon and beyond.

“We’re thrilled with a successful start to the mission and looking forward to what Capstone will do once it arrives at the Moon.”

Read more: Astronomers find closest black hole to Earth

The satellite is currently in low-Earth orbit, and it will take the spacecraft about four months to reach its targeted lunar orbit.

Capstone is attached to Rocket Lab’s Lunar Photon, an interplanetary third stage that will send it on its way to deep space.

Over the next six days, Photon’s engine will periodically ignite to accelerate it beyond low-Earth orbit, where Photon will release the CubeSat on a trajectory to the moon.

Capstone will then use its own propulsion and the sun’s gravity to navigate the rest of the way to the Moon.

The gravity-driven track will dramatically reduce the amount of fuel the CubeSat needs to get to the Moon.

Read more: There might once have been life on the moon

Bradley Cheetham, principal investigator for CAPSTONE and chief executive officer of Advanced Space, “Our team is now preparing for separation and initial acquisition for the spacecraft in six days.

“We have already learned a tremendous amount getting to this point, and we are passionate about the importance of returning humans to the Moon, this time to stay!”

At the moon, Capstone will enter an elongated orbit called a near rectilinear halo orbit, or NRHO.

Once in the NRHO, Capstone will fly within 1,000 miles of the moon’s north pole on its near pass and 43,500 miles from the south pole at its farthest.

It will repeat the cycle every six-and-a-half days and maintain this orbit for at least six months to study dynamics.

“Capstone is a pathfinder in many ways, and it will demonstrate several technology capabilities during its mission timeframe while navigating a never-before-flown orbit around the Moon,” said Elwood Agasid, project manager for Capstone at Nasa’s Ames Research Center in California’s Silicon Valley.

“Capstone is laying a foundation for Artemis, Gateway, and commercial support for future lunar operations.”

Nasa estimates the cost of the whole Artemis mission at $28bn.

It would be the first time people have walked on the moon since the last Apollo moon mission in 1972.

Just 12 people have walked on the moon – all men.

Nasa flew six manned missions to the surface of the moon, beginning with Neil Armstrong and Buzz Aldrin in July 1969, up to Gene Cernan and Jack Schmitt in December 1972.

The mission will use Nasa’s powerful new rocket, the Space Launch System (SLS), and the Orion spacecraft.

Watch: NASA launch paves way for moon orbit station

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The year’s biggest and brightest supermoon will appear in July & here’s when you’ll … – Curiocity

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Summer is here and with it? Sunshine – and some serious moonshine (of the visible variety, of course). This upcoming month, look up in anticipation of the biggest and brightest event of the year, the July Buck supermoon – which will hover over North America on July 13th.

Appearing 7% larger and lower in the sky, this particular event will be one well worth keeping an eye on when it rises above the horizon.

This will be the closest we’ll get to our celestial neighbour in 2022 (357,418 km) and while North America won’t get to see it when it reaches peak illumination at 2:38 pm ETC., it’ll still look pretty dang impressive after the sunsets.

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Not sure when the moon rises in your area? Here’s the earliest that you’ll be able to see the moon in various cities across the continent according to the Farmer’s Almanac.

  • Seattle, Washington  – 9:50 pm PDT
  • Vancouver, British Columbia – 10:02 pm PDT
  • Calgary, Alberta – 10:35 pm MST
  • Edmonton, Alberta – 10:49 pm MST
  • Toronto, Ontario – 9:34 pm MST
  • Montreal, Quebec – 9:18 pm MST

Until then, cross your fingers for a clear sky, friends! It’s going to be incredible.

Happy viewing.

JULY BUCK SUPERMOON 

When: Wednesday, July 13th

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