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Rocky asteroid Ryugu got its rubble from a porous parent, study finds – Space.com

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An image of asteroid Ryugu from Japan’s Hayabusa2 mission.  (Image credit: JAXA/University of Tokyo/Kochi University/Rikkyo University/Nagoya University/Chiba Institute of Technology/Meiji University/University of Aizu/AIST/Kobe University/Auburn University)

The rocky object that spawned the asteroid Ryugu may have been extraordinarily porous, a new study finds. The new discovery could shed light on how planets formed in the solar system.

The most common kind of asteroids found in the outer main asteroid belt are carbonaceous or C-type asteroids. Previous research suggested they are relics of the early solar system that hold troves of primordial material from the nebula that gave birth to the sun and its planets. This makes research into C-type asteroids essential when it comes to understanding planetary formation. 

However, much remains unknown about the physical properties of C-type asteroids. The carbonaceous chondrite meteoroids that are thought to originate from these asteroids often fail to survive entry into Earth’s atmosphere.

Related: Photos of asteroids in deep space

To uncover secrets about C-type asteroids, the Japan Aerospace Exploration Agency (JAXA) dispatched the spacecraft Hayabusa2 to Ryugu, a 2,790-foot-wide (850 meters) near-Earth asteroid that is one of the darkest celestial bodies in the solar system. The C-type asteroid’s name, which means “dragon palace,” refers to a magical underwater castle in a Japanese folk tale. 

In 2018, Hayabusa2 arrived at Ryugu to map it from orbit and deploy rovers on the boulder-covered asteroid. Scientists found Ryugu was only about half as dense as carbonaceous chondrite meteoroids, which suggested the asteroid was essentially a loosely packed pile of rubble that was porous enough to be about 50% empty space.

To learn more about Ryugu, the researchers thermally imaged the asteroid’s surface. Although they had expected its boulders to be denser and therefore colder than their surroundings, they surprisingly found its surface was dominated by boulders that were about the same temperature, suggesting they had a porosity of about 30% to 50%. This was consistent with images from rover pictures that showed that most of the boulders had cauliflower-like, crumbly surfaces.

After sunrise, the asteroid warms up relatively quickly from 230 kelvins (minus 46 degrees Fahrenheit, or minus 43 degrees Celsius) to 300 kelvins (80 F, or 27 C) and cools down again quickly to 230 kelvins after sunset. The fast warming indicates that the surface material has a low density and is highly porous. (Image credit: JAXA)

“Even the 100-meter-class boulders were found to be porous and fragile material,” study lead author Tatsuaki Okada, a planetary scientist at JAXA’s Institute of Space and Astronautical Science in Sagamihara, Japan, told Space.com.

The scientists did see a few dense boulders interspersed among the porous rocks that were about the same density as carbonaceous chondrite meteorites. This leads the researchers to suspect that when meteoroids from C-type asteroids fall to Earth, the crumbly rock that makes up most of these asteroids disintegrates upon entry, with only the denser material surviving, Okada said.

These findings suggest that Ryugu was a rubble pile formed from the fragments of a shattered parent body that was 30% to 50% porous. The few dense boulders seen on Ryugu might have come from the innermost core of this parent body, where the weight of the asteroid would have compressed the spongy rock into something denser, or they might be surviving fragments of meteorite impacts, Okada said.

This graphic shows how scientists believe the asteroid Ryugu formed. First, flakes and grains of dust formed in the disk of dust and gas rotating around the sun. Those grains eventually formed porous planetesimals, or small rocky objects measuring under 1,200 miles (1,900 kilometers) in diameter. When Ryugu’s parent body formed, it was highly porous on the outside, but it had a firmer and denser core, which may explain the presence of both porous and dense rocks on the surface of Ryugu. Collisions with other asteroids decimated Ryugu’s parent body, and some of that debris then stuck together to form Ryugu. The asteroid’s diamond-like shape formed slowly over time due to its rotation. (Image credit: Okada et al./Nature 2020)

“People who live on Earth consider stone a dense and consolidated material, but for a small body, a world of low gravity, a stone is not consolidated and is porous material, because it has never experienced the pressurized conditions like in the Earth’s interior,” Okada said.

All in all, the researchers suggested that C-type asteroids might have formed from fluffy dust or pebbles in the early solar system. The fluffy nature of these asteroids might have strongly influenced planetary formation — for example, the greater ease with which these rocks could crumble might mean that impacts against them were less likely to throw off fragments with great force to shatter other asteroids, they said.

The scientists detailed their findings online March 16 in the journal Nature.

Follow Charles Q. Choi on Twitter @cqchoi. Follow us on Twitter @Spacedotcom and on Facebook.

 

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Here’s how Helene and other storms dumped a whopping 40 trillion gallons of rain on the South

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More than 40 trillion gallons of rain drenched the Southeast United States in the last week from Hurricane Helene and a run-of-the-mill rainstorm that sloshed in ahead of it — an unheard of amount of water that has stunned experts.

That’s enough to fill the Dallas Cowboys’ stadium 51,000 times, or Lake Tahoe just once. If it was concentrated just on the state of North Carolina that much water would be 3.5 feet deep (more than 1 meter). It’s enough to fill more than 60 million Olympic-size swimming pools.

“That’s an astronomical amount of precipitation,” said Ed Clark, head of the National Oceanic and Atmospheric Administration’s National Water Center in Tuscaloosa, Alabama. “I have not seen something in my 25 years of working at the weather service that is this geographically large of an extent and the sheer volume of water that fell from the sky.”

The flood damage from the rain is apocalyptic, meteorologists said. More than 100 people are dead, according to officials.

Private meteorologist Ryan Maue, a former NOAA chief scientist, calculated the amount of rain, using precipitation measurements made in 2.5-mile-by-2.5 mile grids as measured by satellites and ground observations. He came up with 40 trillion gallons through Sunday for the eastern United States, with 20 trillion gallons of that hitting just Georgia, Tennessee, the Carolinas and Florida from Hurricane Helene.

Clark did the calculations independently and said the 40 trillion gallon figure (151 trillion liters) is about right and, if anything, conservative. Maue said maybe 1 to 2 trillion more gallons of rain had fallen, much if it in Virginia, since his calculations.

Clark, who spends much of his work on issues of shrinking western water supplies, said to put the amount of rain in perspective, it’s more than twice the combined amount of water stored by two key Colorado River basin reservoirs: Lake Powell and Lake Mead.

Several meteorologists said this was a combination of two, maybe three storm systems. Before Helene struck, rain had fallen heavily for days because a low pressure system had “cut off” from the jet stream — which moves weather systems along west to east — and stalled over the Southeast. That funneled plenty of warm water from the Gulf of Mexico. And a storm that fell just short of named status parked along North Carolina’s Atlantic coast, dumping as much as 20 inches of rain, said North Carolina state climatologist Kathie Dello.

Then add Helene, one of the largest storms in the last couple decades and one that held plenty of rain because it was young and moved fast before it hit the Appalachians, said University of Albany hurricane expert Kristen Corbosiero.

“It was not just a perfect storm, but it was a combination of multiple storms that that led to the enormous amount of rain,” Maue said. “That collected at high elevation, we’re talking 3,000 to 6000 feet. And when you drop trillions of gallons on a mountain, that has to go down.”

The fact that these storms hit the mountains made everything worse, and not just because of runoff. The interaction between the mountains and the storm systems wrings more moisture out of the air, Clark, Maue and Corbosiero said.

North Carolina weather officials said their top measurement total was 31.33 inches in the tiny town of Busick. Mount Mitchell also got more than 2 feet of rainfall.

Before 2017’s Hurricane Harvey, “I said to our colleagues, you know, I never thought in my career that we would measure rainfall in feet,” Clark said. “And after Harvey, Florence, the more isolated events in eastern Kentucky, portions of South Dakota. We’re seeing events year in and year out where we are measuring rainfall in feet.”

Storms are getting wetter as the climate change s, said Corbosiero and Dello. A basic law of physics says the air holds nearly 4% more moisture for every degree Fahrenheit warmer (7% for every degree Celsius) and the world has warmed more than 2 degrees (1.2 degrees Celsius) since pre-industrial times.

Corbosiero said meteorologists are vigorously debating how much of Helene is due to worsening climate change and how much is random.

For Dello, the “fingerprints of climate change” were clear.

“We’ve seen tropical storm impacts in western North Carolina. But these storms are wetter and these storms are warmer. And there would have been a time when a tropical storm would have been heading toward North Carolina and would have caused some rain and some damage, but not apocalyptic destruction. ”

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Follow AP’s climate coverage at https://apnews.com/hub/climate

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Follow Seth Borenstein on Twitter at @borenbears

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Associated Press climate and environmental coverage receives support from several private foundations. See more about AP’s climate initiative here. The AP is solely responsible for all content.

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‘Big Sam’: Paleontologists unearth giant skull of Pachyrhinosaurus in Alberta

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It’s a dinosaur that roamed Alberta’s badlands more than 70 million years ago, sporting a big, bumpy, bony head the size of a baby elephant.

On Wednesday, paleontologists near Grande Prairie pulled its 272-kilogram skull from the ground.

They call it “Big Sam.”

The adult Pachyrhinosaurus is the second plant-eating dinosaur to be unearthed from a dense bonebed belonging to a herd that died together on the edge of a valley that now sits 450 kilometres northwest of Edmonton.

It didn’t die alone.

“We have hundreds of juvenile bones in the bonebed, so we know that there are many babies and some adults among all of the big adults,” Emily Bamforth, a paleontologist with the nearby Philip J. Currie Dinosaur Museum, said in an interview on the way to the dig site.

She described the horned Pachyrhinosaurus as “the smaller, older cousin of the triceratops.”

“This species of dinosaur is endemic to the Grand Prairie area, so it’s found here and nowhere else in the world. They are … kind of about the size of an Indian elephant and a rhino,” she added.

The head alone, she said, is about the size of a baby elephant.

The discovery was a long time coming.

The bonebed was first discovered by a high school teacher out for a walk about 50 years ago. It took the teacher a decade to get anyone from southern Alberta to come to take a look.

“At the time, sort of in the ’70s and ’80s, paleontology in northern Alberta was virtually unknown,” said Bamforth.

When paleontogists eventually got to the site, Bamforth said, they learned “it’s actually one of the densest dinosaur bonebeds in North America.”

“It contains about 100 to 300 bones per square metre,” she said.

Paleontologists have been at the site sporadically ever since, combing through bones belonging to turtles, dinosaurs and lizards. Sixteen years ago, they discovered a large skull of an approximately 30-year-old Pachyrhinosaurus, which is now at the museum.

About a year ago, they found the second adult: Big Sam.

Bamforth said both dinosaurs are believed to have been the elders in the herd.

“Their distinguishing feature is that, instead of having a horn on their nose like a triceratops, they had this big, bony bump called a boss. And they have big, bony bumps over their eyes as well,” she said.

“It makes them look a little strange. It’s the one dinosaur that if you find it, it’s the only possible thing it can be.”

The genders of the two adults are unknown.

Bamforth said the extraction was difficult because Big Sam was intertwined in a cluster of about 300 other bones.

The skull was found upside down, “as if the animal was lying on its back,” but was well preserved, she said.

She said the excavation process involved putting plaster on the skull and wooden planks around if for stability. From there, it was lifted out — very carefully — with a crane, and was to be shipped on a trolley to the museum for study.

“I have extracted skulls in the past. This is probably the biggest one I’ve ever done though,” said Bamforth.

“It’s pretty exciting.”

This report by The Canadian Press was first published Sept. 25, 2024.

The Canadian Press. All rights reserved.

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The ancient jar smashed by a 4-year-old is back on display at an Israeli museum after repair

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TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.

Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.

Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.

The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.

The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.

It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.

Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.

Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.

Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.

Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.

Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.

The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”

The Canadian Press. All rights reserved.

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