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Simulations show lander exhaust could cloud studies of lunar ices – Phys.org

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An artist’s concept from 1969 depicts a lunar module descending to the Moon’s surface. Because of the Moon’s very thin atmosphere, the exhaust expands significantly and can remain in the atmosphere for months. Credit: NASA/Johnson Space Center

A new study led by scientists at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, shows that exhaust from a mid-sized lunar lander can quickly spread around the Moon and potentially contaminate scientifically vital ices at the lunar poles.

Computer simulations of water vapor emitted by a 2,650-pound (1,200-kilogram) lander—about a quarter of the dry mass of the Apollo Lunar Module—touching down near the Moon’s south pole showed exhaust takes only a few hours to disperse around the entire Moon. From 30% to 40% of the vapor persisted in the lunar atmosphere and surface two months later, and roughly 20% would ultimately freeze out near the poles a few months after that.

Those results, published online Aug. 11 in the Journal of Geophysical Research: Planets, show that researchers’ interest in studying the native ices in the Moon’s poleward craters—ices that may date back several billion years—will need to be carefully considered during increased efforts to return humans to the Moon.

Dealing with spacecraft exhaust on the Moon isn’t a new problem. Researchers appreciated this issue during NASA’s Apollo missions in the ’60s and ’70s, when they developed early models to predict the spread of exhaust throughout the lunar atmosphere and contamination of the surface.

“Exhaust during the Apollo mission didn’t complicate measurements in the same ways that it might now,” said Parvathy Prem, a researcher at APL and the lead author on the study.

Simulations show lander exhaust could cloud studies of lunar ices
Simulation showing how water vapor from a lander’s exhaust spreads throughout the Moon’s atmosphere (shades of blue and red, with warmer tones being denser) and across its surface (shades of purple, with lighter tones being denser) in 24 hours. The exhaust from a landing site near the Moon’s south pole takes only a few hours to spread to the other pole. Credit: Johns Hopkins APL

During the Apollo era, most of the interest was in collecting lunar samples. While that’s still true today, the more recent discovery of ices preserved in permanently shadowed craters near the has shifted scientific interest to understanding the origin and dispersion of water and other volatile molecules on the Moon’s surface and in its thin atmosphere.

“These are some of the only places where we can find traces of the origin of water in the inner solar system,” Prem said. Reading that record requires measuring the composition of those ices as well as their various isotopes to deduce where they likely came from and how they may have gotten there. Frozen-out exhaust gases from robotic or that collect on those ices could confound those measurements, even if the lander touches down hundreds of miles away.

“The interesting thing about Parvathy’s work is that it shows very well that the effect, while small and temporary, is global,” said Dana Hurley, a planetary scientist at APL and coauthor on the study.

Space organizations can expect volatile gases to significantly coat the lunar surface at well over 60 miles (100 kilometers) from the .

The residue exhaust does eventually fade away, but Hurley points out that current plans for human lunar exploration mean it will happen more frequently and with much heavier landers.

Simulations show lander exhaust could cloud studies of lunar ices
Image showing the distribution of surface ices (depicted as blue dots) at the Moon’s south pole (left) and north pole (right), detected by NASA’s Moon Mineralogy Mapper instrument. The grayscale in this image depicts temperature, with darker being colder, showing the ices are concentrated in the darkest and coldest locations, the crater shadows. Credit: NASA

“The results of this study drive the critical need to conduct the research we want to do about the and volatile deposits while they are relatively pristine,” Hurley said.

Prem cautions that the model isn’t foolproof. Among its most salient limitations are that it assumes the degree to which water interacts and “sticks” to the lunar surface, which is still uncertain but of great interest for understanding how easily water is transported around the Moon. The model also tracks only water vapor, which comprises about a third of the composition of most landers’ exhaust. Other exhaust molecules, such as hydrogen, ammonia and carbon monoxide, may behave differently and perhaps persist even longer.

Follow-up work should include measuring the amount of exhaust that’s around the Moon during and after future landings, Prem said, which would help narrow in on an answer to how much these exhaust gases “stick” to the surface. “But I would also suggest that modeling and monitoring the fate of exhaust gases should be a routine part of lunar mission development and planning.”

Conversations about mitigating exhaust gases have only just started, Prem explained.

In January, NASA finalized 16 science and technology demonstration payloads that it had selected to be delivered to the Moon through the Artemis program, including the Surface Exosphere Alterations by Landers (SEAL), an instrument that will investigate the chemical response of the lunar during a landing as well as any contaminants that may have been injected.

“Whether we intend to or not, we’re going to do this experiment of bringing exhaust gases with us,” Prem said. It’s now a matter of deciding how we deal with them.


Explore further

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More information:
Parvathy Prem et al. The Evolution of a Spacecraft‐Generated Lunar Exosphere, Journal of Geophysical Research: Planets (2020). DOI: 10.1029/2020JE006464

Citation:
Simulations show lander exhaust could cloud studies of lunar ices (2020, August 14)
retrieved 14 August 2020
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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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‘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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