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The mystery of Earth’s vanishing crust solved – Tech Explorist

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The Earth’s crust is what we live on and is by far the thinnest layers of Earth. The thickness varies depending on where you are on Earth, with the oceanic crust being 5-10 km and continental mountain ranges being up to 30-45 km thick. 

But what happens below this crust remains obscure, including the fate of sections of crust that vanish back into the Earth.

Now, a team of geochemists based at the Florida State University-headquartered National High Magnetic Field Laboratory has found some significant clues about where those rocks have been hiding.

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A new study has come out with fresh evidence that while most of the Earth’s crust is relatively new, a small percentage is made up of ancient chunks that had sunk long ago back into the mantle then later resurfaced. They also found that based on the amount of that “recycled” crust, that the planet had been churning out crust consistently since its formation 4.5 billion years ago—a picture that contradicts prevailing theories.

Co-author Munir Humayun, a MagLab geochemist and professor at Florida State’s Department of Earth, Ocean, and Atmospheric Science (EOAS) said, “Like salmon returning to their spawning grounds, some oceanic crust returns to its breeding ground, the volcanic ridges where the fresh crust is born. We used a new technique to show that this process is essentially a closed-loop and that recycled crust is distributed unevenly along ridges.”

Recycled ancient crust returns to the oceanic ridges. Credit: Caroline McNiel/National MagLab

Scientists have long estimated about what happens to subducted crust after being reabsorbed into the hot, high-pressure environment of the planet’s mantle. It may sink further into the mantle and settle there, or ascend back to the surface in tufts, or to the surface in plumes, or swirl through the mantle.

Scientists had already seen clues supporting the theory. Some basalts collected from mid-ocean ridges, called enriched basalts, have a higher percentage of certain elements that tend to seep from the mantle into the melt from which basalt is formed; others, called depleted basalts, had much lower levels.

To highlight the mystery of the disappearing crust, scientists observed 500 samples of basalt collected from 30 regions of ocean ridges. Some were enriched, some were depleted, and some were in between.

Scientists discovered that the overall extents of germanium and silicon were lower in melts of the recycled crust than in the “virgin” basalt rising out of melted mantle rock. So they built up another strategy that pre-owned that proportion to distinguish a particular chemical fingerprint for the subducted crust.

They thus devised an accurate technique to measure the ratio using a mass spectrometer at the MagLab. Then they crunched the numbers to see how these ratios differed among the 30 regions sampled, expecting to see variations that would shed light on their origins.

Scientists first discovered nothing. This concerned scientists, and they started looking at the problem from a wider view. Instead of comparing the basalts of different regions, they compared enriched and depleted basalts.

After quickly re-crunching the data, scientists were thrilled to see apparent differences among those groups of basalts.

The team had detected lower germanium-to-silicon ratios in enriched basalts—the chemical fingerprint for the recycled crust—across all the regions they sampled, pointing to its marble cake-like spread throughout the mantle. Essentially, they solved the mystery of the vanishing crust.

Humayun said, “Sometimes you’re looking too closely, with your nose in the data, and you can’t see the patterns. Then you step back, and you go, ‘Whoa!’”

Digging deeper into the patterns they found, the scientists unearthed more secrets. Based on the amounts of enriched basalts detected on global mid-ocean ridges, the team was able to calculate that about 5 to 6 percent of the Earth’s mantle is made of recycled crust. This figure sheds new light on the planet’s history as a crust factory. Scientists had known the Earth cranks out crust at the rate of a few inches a year. But has it done so consistently throughout its entire history?

Their analysis, Humayun said, indicates that “The rates of crust formation can’t have been radically different from what they are today, which is not what anybody expected.”

Journal Reference:
  1. Elemental constraints on the amount of recycled crust in the generation of mid-oceanic ridge basalts (MORBs)” Science Advances (2020). DOI: /10.1126/sciadv.aba2923

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Dragonfly: NASA Just Confirmed The Most Exciting Space Mission Of Your Lifetime – Forbes

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NASA has confirmed that its exciting Dragonfly mission, which will fly a drone-like craft around Saturn’s largest moon, Titan, will cost $3.35 billion and launch in July 2028.

Titan is the only other world in the solar system other than Earth that has weather and liquid on the surface. It has an atmosphere, rain, lakes, oceans, shorelines, valleys, mountain ridges, mesas and dunes—and possibly the building blocks of life itself. It’s been described as both a utopia and as deranged because of its weird chemistry.

Set to reach Titan in 2034, the Dragonfly mission will last for two years once its lander arrives on the surface. During the mission, a rotorcraft will fly to a new location every Titan day (16 Earth days) to take samples of the giant moon’s prebiotic chemistry. Here’s what else it will do:

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  • Search for chemical biosignatures, past or present, from water-based life to that which might use liquid hydrocarbons.
  • Investigate the moon’s active methane cycle.
  • Explore the prebiotic chemistry in the atmosphere and on the surface.

Spectacular Mission

“Dragonfly is a spectacular science mission with broad community interest, and we are excited to take the next steps on this mission,” said Nicky Fox, associate administrator of the Science Mission Directorate at NASA Headquarters in Washington. “Exploring Titan will push the boundaries of what we can do with rotorcraft outside of Earth.”

It comes in the wake of the Mars Helicopter, nicknamed Ingenuity, which flew 72 times between April 2021 and its final flight in January 2023 despite only being expected to make up to five experimental test flights over 30 days. It just made its final downlink of data this week.

Dense Atmosphere

However, Titan is a completely different environment to Mars. Titan has a dense atmosphere on Titan, which will make buoyancy simple. Gravity on Titan is just 14% of the Earth’s. It sees just 1% of the sunlight received by Earth.

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The atmosphere is 98% nitrogen and 2% methane. Its seas and lakes are not water but liquid ethane and methane. The latter is gas in Titan’s atmosphere, but on its surface, it exists as a liquid in rain, snow, lakes, and ice on its surface.

COVID-Affected

Dragonfly was a victim of the pandemic. Slated to cost $1 billion when it was selected in 2019, it was meant to launch in 2026 and arrive in 2034 after an eight-year cruise phase. However, after delays due to COVID, NASA decided to compensate for the inevitable delayed launch by funding a heavy-lift launch vehicle to massively shorten the mission’s cruise phase.

The end result is that Dragonfly will take off two years later but arrive on schedule.

Previous Visit

Dragonfly won’t be the first time a robotic probe has visited Titan. As part of NASA’s landmark Cassini mission to Saturn between 2004 and 2017, a small probe called Huygens was despatched into Titan’s clouds on January 14, 2005. The resulting timelapse movie of its 2.5 hours descent—which heralded humanity’s first-ever (and only) views of Titan’s surface—is a must-see for space fans. It landed in an area of rounded blocks of ice, but on the way down, it saw ancient dry shorelines reminiscent of Earth as well as rivers of methane.

The announcement by NASA makes July 2028 a month worth circling for space fans, with a long-duration total solar eclipse set for July 22, 2028, in Australia and New Zealand.

Wishing you clear skies and wide eyes.

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Scientists claim evidence of 'Planet 9' in our solar system – Supercar Blondie

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A team of scientists claims to have evidence that there is another hidden planet – nicknamed ‘Planet 9’ – lurking in our solar system.

Of course, there have been changes to the number of planets in our solar system over recent – in space terms, anyway – years, as Pluto is no longer considered a proper planet.

Seems a bit harsh, doesn’t it?

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However, a team of astronomers now believe that they have the strongest evidence yet that there is another mysterious planet hovering around our sun.

READ MORE! James Webb Telescope observes light on Earth-like planet for the first time in history

The theory that there could be other planets orbiting our star has been around for years, as scientists have noticed some unusual phenomena on the edge of the solar system that suggest the existence of another celestial body.

The theory that another planet is responsible would also explain the orbit of other objects that are outliers in our system, sitting more than 250 times Earth’s distance from the sun.

Scientist Konstantin Bogytin and his team have long been proponents of this ‘Planet 9’ theory, and now they believe they have ‘the strongest statistical evidence yet that Planet 9 is really out there’.

As we know, it wouldn’t be the only strange thing in our solar system.

Or outside, for that matter.

Perhaps they just need to point a massive space telescope at it and they’ll find evidence of alien life out there.

This new study by Bogytin and his team focused on a number of Trans-Neptunian Objects (TNOs) that lie outside the orbit of Neptune towards the outer reaches of our solar system.

In analyzing the movements of these objects – which can be affected by the orbit of Neptune, as well as passing stars and the ‘galactic tide’ – the scientists concluded that there could be another unseen planet out there.

Dr Bogytin pointed out that there are other potential explanations for the behavior of these objects, but – he believes – Planet 9 is the best bet.

Once the Vera C. Rubin Observatory in Chile becomes active, we might get the best look we’ve had yet.

In a paper, the team wrote: “This upcoming phase of exploration promises to provide critical insights into the mysteries of our solar system’s outer reaches.”

That paper, entitled ‘Generation of Low-Inclination, Neptune-Crossing TNOs by Planet Nine’ is available to read here.

Images in this article were generated using AI

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Marine plankton could act as alert in mass extinction event: UVic researcher – Saanich News

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A University of Victoria micropaleontologist found that marine plankton may act as an early alert system before a mass extinction occurs.

With help from collaborators at the University of Bristol and Harvard, Andy Fraass’ newest paper in the Nature journal shows that after an analysis of fossil records showed that plankton community structures change before a mass extinction event.

“One of the major findings of the paper was how communities respond to climate events in the past depends on the previous climate,” Fraass said in a news release. “That means that we need to spend a lot more effort understanding recent communities, prior to industrialization. We need to work out what community structure looked like before human-caused climate change, and what has happened since, to do a better job at predicting what will happen in the future.”

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According to the release, the fossil record is the most complete and extensive archive of biological changes available to science and by applying advanced computational analyses to the archive, researchers were able to detail the global community structure of the oceans dating back millions of years.

A key finding of the study was that during the “early eocene climatic optimum,” a geological era with sustained high global temperatures equivalent to today’s worst case global warming scenarios, marine plankton communities moved to higher latitudes and only the most specialized plankton remained near the equator, suggesting that the tropical temperatures prevented higher amounts of biodiversity.

“Considering that three billion people live in the tropics, the lack of biodiversity at higher temperatures is not great news,” paper co-leader Adam Woodhouse said in the release.

Next, the team plans to apply similar research methods to other marine plankton groups.

Read More: Global study, UVic researcher analyze how mammals responded during pandemic

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