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NASA begins critical final test on mega Moon rocket

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02/04/2022

NASA begins critical final test on mega Moon rocket

NASA on Friday began a critical two-day-long test of its giant Space Launch System (SLS) rocket complete with a simulated countdown, as the agency gears up to return humans to the Moon.

Known as the “wet dress rehearsal,” it is the final major test before the Artemis-1 mission this summer: an uncrewed lunar flight that will eventually be followed by boots on the ground, likely no sooner than 2026.

“The countdown is now underway,” NASA said in its Artemis blog at 5:00 pm Eastern Time (2100 GMT), confirming members of the launch control team had been issued their “call to stations.”

Data from the test, which ends Sunday mid-afternoon, will be used to finalize a launch date for Artemis 1. NASA had said May could be the first window, but later now seems likely.

It is called a “wet” dress rehearsal because supercooled liquid hydrogen and liquid oxygen will be loaded into SLS from ground systems, just as they would be in a real launch.

The 322-foot (98-meter) rocket—expected to be the most powerful in history at the time it is operational—was rolled out to Launch Complex 39B at the Kennedy Space Center in Florida around two weeks ago.

Teams are now filling up a sound suppression system with water that is used to dampen acoustic energy during lift-off. They will continue to practice every operation that would be carried out in a real launch.

Come Sunday morning, with the SLS rocket and Orion crew capsule fixed atop both powered on, they will load up 700,000 gallons (2.6 million liters) of propellant.

They won’t actually ignite the rocket’s RS-25 engines, which were tested previously. Instead they will halt the countdown about 10 seconds before liftoff, in order to simulate a “scrub,” when launch is aborted due to technical or weather related issues.

The fuel will be drained, and a few days later SLS and Orion will be rolled back to the vehicle assembly building to carry out checks on how everything went.

Test milestones will be posted on NASA’s blog for the Artemis mission, and the public might be able to glimpse the rocket venting vapor on the launch pad on April 3, during tanking operations, on the agency’s YouTube channel.

On Monday, agency officials plan to hold a press conference to give further information.

NASA won’t however let the public listen to live internal audio.

Senior NASA official Tom Whitmeyer explained this was because certain key information, including timing sequences, could assist other countries looking to develop long range missiles, and fall foul of export control regulations called International Traffic in Arms Regulations (ITAR).

“We’re really, really super sensitive to cryogenic launch vehicles that are of this size and capability, (and) are very analogous to ballistic type capabilities that other countries are very interested in,” he said, but added that the agency could re-evaluate the position in future.

The decision has caused some confusion, as commercial launch companies routinely make their countdown audio available, while most intercontinental ballistic missiles run on solid fuel, not liquid propellants.

Astrophysicists set constraints on compact dark matter from gravitational wave microlensing

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02/04/2022

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Astrophysicists set constraints on compact dark matter from gravitational wave microlensing

The existence of dark matter remains one of the greatest mysteries of the universe. While studies have indirectly hinted at its existence, its invisible nature makes this elusive substance very difficult to detect, thus its composition remains unknown.

Dark matter could be made of fundamental and exotic particles that are yet to be discovered. Alternatively, it could consist of many massive and compact objects, such as primordial black holes (i.e., black holes formed in the early universe).

Over the past decades, many teams of scientists worldwide have been searching for dark matter, using a multitude of techniques, telescopes, detectors and observational data. While most of these searches were unsuccessful, they helped to guide and narrow down subsequent searches.

Researchers at Tata Institute of Fundamental Research’s International Centre for Theoretical Studies in Bangalore, India, have recently set new constraints on the fraction of compact dark matter from gravitational wave microlensing. Their paper, published in The Astrophysical Journal Letters, introduces a new way of probing the nature of dark matter by looking for microlensing effects in gravitational waves.

“According to Einstein’s theory of general relativity, massive objects bend light as normal optical lenses do,” Parameswaran Ajith, one of the researchers who carried out the study, told Phys.org. “Massive objects, such as black holes that lie in between the astronomical source and the observer, can magnify the source. This phenomenon, called gravitational microlensing, has emerged to be a powerful tool for astronomers.”

Despite the extensive research efforts in the field, astronomers have so far been unable to observe the microlensing effects produced by black holes. This suggests that black holes that are much lighter than the sun, which would produce the microlensing of light, are rare.

“Even if these black holes exist, they are likely to constitute only a very small fraction of the dark matter,” Ajith said. “Theory predicts that gravitational waves will also be lensed in the same way. If primordial black holes that are much more massive than the sun are abundant in the universe, they will distort the gravitational waves.”

In 2003, some theoretical physicists accurately calculated the nature of gravitational wave distortions. Almost two decades later, Sunghoon Jung and Chang Sub Shin, two scientists at Seoul National University and the IBS Center for Theoretical Physics of the Universe suggested that the non-observation of these distortions by the LIGO and Virgo collaborations could help to constrain the abundance of black holes that are significantly more massive than the sun.

The recent paper by Ajith and his colleagues draws inspiration from these previous works. The team’s work is based on the assumption that if a significant fraction of dark matter were actually comprised of compact objects, these objects would cause microlensing effects in the gravitational wave signals periodically detected by the LIGO and Virgo detectors.

“Back in 2018, in collaboration with colleagues in the LIGO-Virgo Collaboration, we had searched for signatures of such distortions in the gravitational-wave signals observed by LIGO and Virgo and found none,” Ajith said. “However, since LIGO and Virgo had observed only 10 gravitational-wave signals by then, our prior expectation for finding such distortions was low.”

Recently LIGO-Virgo Collaboration announced similar null results from its third observing run. “In addition, Ajith and his colleagues independently analyzed the gravitational waves that a group at the Institute for Advanced Studies (IAS) in Princeton had uncovered within the LIGO-Virgo data. Overall, they thus analyzed more than 50 gravitational wave events.

While the researchers were unable to observe microlensing distortions in any of the signals they analyzed, their analyses allowed them to set further constraints on compact dark matter. In other words, they constrained the fraction of dark matter that consists of massive black holes.

“The constraints that we obtained so far are quite modest,” Ajith said. “All we can say is that not more than 50% of the dark matter is in the form of massive black holes, which is not new information. However, in the next few years, LIGO and Virgo are expected to observe hundreds to thousands of gravitational-wave signals. These observations will allow us to improve these constraints significantly.”

In the future, Ajith and his colleagues plan to analyze all new gravitational wave events recorded by the LIGO-Virgo detectors. In addition, they hope that their recent work will encourage other teams to use the microlensing of gravitational waves to investigate the nature of dark matter.

“As part of the LIGO-Virgo Collaboration, we are analyzing all the gravitational wave signals detected by LIGO and Virgo during their past three observing runs (a total of close to 100 events),” Ajith added. “This will improve the constraint a little bit. However, we are looking forward to analyzing data from the next observing run, where LIGO and Virgo are expected to observe hundreds of gravitational-wave signals!”

More information: S. Basak et al, Constraints on Compact Dark Matter from Gravitational Wave Microlensing, The Astrophysical Journal Letters (2022). DOI: 10.3847/2041-8213/ac4dfa
Journal information: Astrophysical Journal Letters

U.S. can get close to deep decarbonization by 2050

ENVIRONMENT

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02/04/2022

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U.S. can get close to deep decarbonization by 2050

The United States will get only partially toward deep reductions in greenhouse gasses with the policy tools currently available even in the scenario most favorable politically to decarbonization. That’s the finding of a recent study published in Energy Policy by an interdisciplinary team of researchers at The University of Texas at Austin that looked at the political feasibility of deep decarbonization in the United States. The results suggest that new policies and tools will be needed to reduce greenhouse gasses from sectors such as heavy industry.

The researchers, using the TIMES energy system optimization model, analyzed midcentury emissions of greenhouse gasses based on three scenarios of political feasibility—all with a Democrat in the White House and a Democratically controlled U.S. House of Representatives. In what the researchers call the low alignment scenario, Republicans control the Senate. In the medium alignment scenario, Democrats control the Senate with the filibuster intact. And in the high alignment scenario, Democrats control the Senate and the filibuster is abolished.

The team found that even in the most optimistic of scenarios, the U.S. only partially meets an 80% decarbonization goal by 2050. If Republicans control the Senate, the suite of politically feasible policies would permit greenhouse gas emissions to fall only by one-fourth by 2050. In the scenario where Democrats control the Senate with the filibuster intact, emissions are reduced by about one-third given politically possible policies. If Democrats control the Senate and the filibuster is eliminated, policies currently available enable greenhouse gas emissions to decline by about 45%.

“This interdisciplinary project brings needed policy realism to energy system modeling and reminds us that achieving deep decarbonization will require further policy innovation,” said Benjamin Leibowicz, an assistant professor in the Cockrell School of Engineering and a lead author of the study. “While the electricity sector is already decarbonizing at a fast pace, new technologies and policies will be needed to address greenhouse gas sources such as heavy-duty vehicles, aviation, natural gas use in buildings, and industrial production.”

The researchers also found that in scenarios where politics align with more comprehensive climate policy, achieving greater emission reductions is actually less costly. Average costs are lower under greater political alignment because technology-neutral policies, such as a comprehensive carbon price via a tax or cap-and-trade, allow businesses and households to reduce emissions in whatever manner is cheapest. Despite having the upper hand in economic terms, however, carbon pricing does not have broad political support.

Much of the decarbonization in the models comes from deploying renewables in the electricity sector, particularly wind and solar. There are also signs of bipartisan support in the buildings sector, especially with regard to building energy performance standards, investments in the Weatherization Assistance Program, and tax credits for solar-powered systems. Electrification in the transportation sector is one of the most important drivers of emissions reductions. Even though transportation is a more difficult sector to decarbonize given residual emissions from heavy trucks, incentivizing the swifter transition to electric vehicles will have an important impact on broader climate goals.

In each of the three scenarios, different policies were identified as being politically available and then modeled for their impact on greenhouse gas emissions.

Low alignment assumes a Republican-controlled Senate where policies that enjoy bipartisan support can pass such as tax credits, research and development funding, standards for federal procurement and regulations, and fossil-industry-backed strategies such as carbon capture, utilization and storage. The medium alignment portfolio, which assumes a Democratic-controlled Senate retaining the filibuster, includes more regulatory instruments such as sectoral carbon taxes, which are seen as market-friendly and could attract Republican support. The High Alignment portfolio assumes Democratic control of the Senate with no filibuster and includes more mandates and standards such as a clean electricity standard.

More information: Qianru Zhu et al, Enhancing policy realism in energy system optimization models: Politically feasible decarbonization pathways for the United States, Energy Policy (2021). DOI: 10.1016/j.enpol.2021.112754
Journal information: Energy Policy

‘Flash droughts’ coming on faster, global study shows

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02/04/2022

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‘Flash droughts’ coming on faster, global study shows

Just like flash floods, flash droughts come on fast—drying out soil in a matter of days to weeks. These events can wipe out crops and cause huge economic losses. And according to scientists, the speed at which they dry out the landscape has increased.

Researchers at The University of Texas at Austin, The Hong Kong Polytechnic University and Texas Tech University found that although the number of flash droughts has remained stable during the past two decades, more of them are coming on faster. Globally, the flash droughts that come on the fastest—sending areas into drought conditions within just five days—have increased by about 3%-19%. And in places that are especially prone to flash droughts—such as South Asia, Southeast Asia and central North America—that increase is about 22%-59%.

Rising global temperatures are probably behind the faster onset, said co-author and UT Jackson School Professor Zong-Liang Yang, who added that the study’s results underscore the importance of understanding flash droughts and preparing for their effects.

“Every year, we are seeing record-breaking warming episodes, and that is a good precursor to these flash droughts,” he said. “The hope and purpose [of this research] is to minimize the detrimental effects.”

The research was published in Nature Communications. The study was led by doctoral student Yamin Qing and Professor Shuo Wang, both of The Hong Kong Polytechnic University.

Flash droughts are relatively new to science, with the advancement of remote sensing technology during the past couple of decades helping reveal instances of soil rapidly drying out. This serves as the telltale sign of the onset of a flash drought and can make drought conditions appear seemingly out of the blue.

As the name suggests, flash droughts are short lived, usually lasting only a few weeks or months. But when they occur during critical growing periods, they can cause disasters. For example, in the summer of 2012, a flash drought in the central United States caused the corn crop to wither, leading to an estimated $35.7 billion in losses.

In this study, the scientists analyzed global hydroclimate data sets that use satellite soil moisture measurements to capture a global picture of flash drought and how it has changed during the past 21 years. The data showed that about 34%-46% of flash droughts came on in about five days. The rest emerge within a month, with more than 70% developing in half a month or less.

When they examined the droughts over time, they noticed the flash droughts happening more quickly.

The study also revealed the importance of humidity and variable weather patterns, with flash droughts becoming more likely when there’s a shift from humid to arid conditions. That makes regions that undergo seasonal swings in humidity—such as Southeast Asia, the Amazon Basin, and the East Coast and Gulf Coast of the United States—flash drought hot spots.

“We should pay close attention to the vulnerable regions with a high probability of concurrent soil drought and atmospheric aridity,” said Wang.

Mark Svoboda, the director of the National Drought Mitigation Center and originator of the term “flash drought,” said the advancement in drought-detecting technology and modeling tools—such as those used in this study—has led to growing awareness of the influence and impact of flash droughts. He said the next big step is translating this knowledge into on-the-ground planning.

“You can go back and watch that drought evolve in 2012 and then compare it to how that tool did,” said Svoboda, who was not part of the study. “We really have the stage well set to do a better job of tracking these droughts.”

More information: Yamin Qing et al, Accelerating flash droughts induced by the joint influence of soil moisture depletion and atmospheric aridity, Nature Communications (2022). DOI: 10.1038/s41467-022-28752-4
Provided by University of Texas at Austin

First audio recorded on Mars reveals two speeds of sound

MARS

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01/04/2022

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First audio recorded on Mars reveals two speeds of sound

The first audio recordings on Mars reveal a quiet planet with occasional gusts of wind where two different speeds of sound would have a strange delayed effect on hearing, scientists said Friday.

After NASA’s Perseverance rover landed on Mars in February last year, its two microphones started recording, allowing scientists to hear what it is like on the Red Planet for the first time.

In a study published in the Nature journal on Friday, the scientists gave their first analysis of the five hours of sound picked up by Perseverance’s microphones.

The audio revealed previously unknown turbulence on Mars, said Sylvestre Maurice, the study’s main author and scientific co-director of the shoebox-sized SuperCam mounted on the rover’s mast which has the main microphone.

The international team listened to flights by the tiny Ingenuity helicopter, a sister craft to Perseverance, and heard the rover’s laser zap rocks to study their chemical composition—which made a “clack clack” sound, Maurice told AFP.

“We had a very localized sound source, between two and five meters (six to 16 meters) from its target, and we knew exactly when it was going to fire,” he said.

Hear What Familiar Earth Sounds Would Be Like on Mars

The study confirmed for the first time that the speed of sound is slower on Mars, traveling at 240 meters per second, compared to Earth’s 340 meters per second.

This had been expected because Mars’ atmosphere is 95 percent carbon dioxide—compared to Earth’s 0.04 percent—and is about 100 times thinner, making sound 20 decibels weaker, the study said.

Most of the time, Mars is very quiet, scientists say

‘I panicked’

But the scientists were surprised when the sound made by the laser took 250 meters a second—10 meters faster than expected.

“I panicked a little,” Maurice said. “I told myself that one of the two measurements was wrong because on Earth you only have one speed of sound.”

They had discovered there are two speeds of sound on the surface of Mars—one for high-pitched sounds like the zap of the laser, and another for lower frequencies like the whir of the helicopter rotor.

This means that human ears would hear high-pitched sounds slightly earlier.

“On Earth, the sounds from an orchestra reach you at the same speed, whether they are low or high. But imagine on Mars, if you are a little far from the stage, there will be a big delay,” Maurice said.

“All of these factors would make it difficult for two people to have a conversation only five meters (16 feet) apart”, the French CNRS research institute said in a statement.

NASA's Perseverance is the fifth rover to set wheels down on Mars — NASA’s Perseverance is the fifth rover to set wheels down on Mars

‘Scientific gamble’ pays off

It was otherwise so quiet on Mars that the scientists repeatedly feared something was wrong, the CNRS said, possibly provoking memories of two failed previous attempts in 1999 and 2008 to record sound there.

“There are few natural sound sources with the exception of the wind,” the scientists said in a statement linked to the study.

The microphones did pick up numerous “screech” and “clank” sounds as the rover’s metal wheels interacted with rocks, the study said.

The recording could also warn about problems with the rover—like how drivers sense something’s wrong when their car starts making strange noises.

Maurice said he felt the “scientific gamble” of taking microphones to Mars was a success.

Thierry Fouchet of the Paris Observatory, who was also involved in the research, said that listening to turbulence, such as vertical winds known as convection plumes, will “allow us to refine our numerical models for predicting climate and weather”.

Future missions to Venus or Saturn’s moon Titan could also now come equipped with microphones.

And Perseverance is far from done eavesdropping. While its core mission lasts just over two years, it could remain operational well beyond that—the Curiosity rover is still kicking nine years into a planned two-year stint.

More information: S. Maurice et al, In situ recording of Mars soundscape, Nature (2022). DOI: 10.1038/s41586-022-04679-0

Journal information: Nature

Team develops new method of hunting for carbon in soil without digging or taking soil samples

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01/04/2022

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Team develops new method of hunting for carbon in soil without digging or taking soil samples

Physicists and soil scientists at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) have teamed up to develop a new method for finding carbon stored in the soil by plants and microbes. Unlike all previous methods, this new technique makes it possible to see the carbon in the dirt without digging holes or taking soil samples, like an X-ray for the soil. This new method for measuring carbon pulled out of the air promises to be an important tool for fighting climate change and developing more ecologically friendly forms of agriculture.

“What this instrument really enables is repeated measurements over time,” said Arun Persaud, a Berkeley Lab physicist and one of the leaders of the team. “With our instrument, you can get a very accurate and fast measurement of the total carbon in an acre of land, without disturbing the soil or harming the organisms that live there.”

A plant transfers carbon into the soil as a natural part of its life cycle. Plants breathe in carbon dioxide and breathe out oxygen (which we animals then breathe in). The carbon remains in the plant, used to build molecules and cells it needs to live. A large fraction of that carbon ultimately enters the soil through the plant’s roots. Microbes in the soil then take this carbon and turn it into organic matter that can persist for decades, centuries, or longer.

Plants and soil microbes play a key role in the Earth’s carbon cycle—a cycle that humans have drastically altered. Burning fossil fuels heats up the planet quickly. Human land use for agriculture has depleted organic matter in the soil, resulting in an enormous soil carbon deficit that also contributes to climate change.

Pulling large amounts of carbon out of the atmosphere is a vital component in virtually all plans to limit global warming to 2 degrees Celsius or less. This need is the impetus behind Berkeley Lab’s Carbon Negative Initiative, which aims to develop technologies to capture, sequester, and use carbon dioxide. Plants and microbes are experts on pulling carbon out of the atmosphere—they’ve been doing it for billions of years. But before we can harness them to help manage atmospheric carbon, we need to accurately measure how much carbon is already locked in the soil through plant-microbial interactions, or other management strategies. Unfortunately, existing techniques for testing the carbon content of the soil are quite destructive, and error-prone at large scales.

“We have a major limitation in understanding and quantifying how carbon enters and persists in soil because of the way that we measure it,” said Eoin Brodie, a Berkeley Lab scientist. “Typically we would take a soil core sample from a position in a field and bring it back to the lab. Then we’d basically burn it and measure the carbon that’s released. It’s extremely laborious and costly to do that, and you don’t even know how representative those cores are.”

Brodie is Deputy Director of Berkeley Lab’s Climate and Ecosystem Sciences Division and one of the leaders of the EcoSENSE Program, a component of the Biological & Environmental Program Integration Center (BioEPIC) currently in development. EcoSENSE aims to create suites of sensors to monitor the impacts of climate and weather on ecosystem function, and Brodie and his colleagues wanted to find a better way to measure carbon in the soil. The broad scientific expertise available at Berkeley Lab, and a timely call for proposals on below-ground sensor technologies from DOE’s Advanced Research Projects Agency-Energy (ARPA-E), led Brodie, Persaud, and their colleagues to team up on this project. “What it really took was communication across very different programs at Berkeley Lab,” said Brodie. “We became aware of this potentially useful technology in the Accelerator Technology & Applied Physics (ATAP) Division, and we joined forces.” Ultimately the cross-disciplinary team was awarded a grant from ARPA-E’s Rhizosphere Observations Optimizing Terrestrial Sequestration (ROOTS) program, which enabled this work.

The new method of measurement developed by the Berkeley Lab team eliminates the need to dig anything out of the ground at all. Instead, the as-yet-unnamed device scans the soil with a beam of neutrons. Then a detector senses the faint response of the carbon and other elements in the soil to the neutrons, allowing it to map the distribution of different elements within the soil to a resolution of about five centimeters. All this happens above the ground, with no holes, no cores, and no burning. “It’s like giving the soil an MRI,” said Persaud, who is a staff scientist in ATAP. “We get a three-dimensional picture of the soil and the carbon distribution in it, along with other elements like iron, silicon, oxygen, and aluminum, which are all important to understand the persistence of carbon in soil.”

“What really excites me about this neutron imaging approach is that it lets us effectively and accurately image the carbon distributions in soils at the scales that carbon accounting needs to happen at,” added Brodie. “And we can do it repeatedly over growing seasons, to see how it’s changing with different climates and land management practices. Eventually you could use this to identify what specific land management practices are more effectively drawing carbon down from the atmosphere and storing it in soil.”

“This new carbon sensing method is an example of thinking outside the box and bringing together researchers from diverse backgrounds—here physical sciences and earth science—to create new technology addressing the challenges of climate change,” said Cameron Geddes, director of ATAP.

Right now the project is just emerging from the lab, and Persaud, Brodie, and their colleagues are about to test it in real soils in an outdoor system soon. “We’re really excited to test this on the soil here at Berkeley Lab after the rainy season,” Persaud said.

“The next step is making this process field deployable and more automated, so that it can be incorporated onto things like combine harvesters and tractors, so that this becomes part of the sensing capabilities that you find in farms and across forests,” Brodie added. “There’s really huge, huge potential in this.”

More information: Mauricio Ayllon Unzueta et al, An all-digital associated particle imaging system for the 3D determination of isotopic distributions, Review of Scientific Instruments (2021). DOI: 10.1063/5.0030499

Journal information: Review of Scientific Instruments

Provided by Lawrence Berkeley National Laboratory

Mounds of ice in craters give new insight into Mars’ past climate

MARS

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01/04/2022

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Mounds of ice in craters give new insight into Mars’ past climate

Newly discovered deposits of layered ice in craters scattered around Mars’ southern hemisphere provide insights into how the planet’s orientation controlled the planet’s climate over the past 4 million years, according to a new study. The findings help scientists understand what controlled Mars’ past climate, which is essential for predicting when the planet could have been habitable.

The study was published in the AGU journal Geophysical Research Letters, which publishes short-format, high-impact research with implications spanning the Earth and space sciences.

Ice deposits on Mars reflect a combination of temperature, hydrology and planetary dynamics, as they do on Earth. The planet’s tilt and orbit impact temperature and sunlight on the surface, which contribute to climate. Thicker, more pure ice layers generally reflect cold periods with more ice accumulation, while thin, dusty layers were likely warmer and less able to build up ice.

The new study matches these ice layers to the tilt of Mars’ axis and its orbital precession, or how the planet’s elliptical orbit rotates around the sun over time, with unprecedented resolution and confidence.

The findings give scientists insight into how Mars’ climate has changed over time. While the study is limited to the recent past, establishing these climate-orbit relationships helps scientists understand Martian climate deeper in the past, which could help pinpoint periods of potential habitability.

“It was unexpected how cleanly those patterns matched to the orbital cycles,” said lead study author Michael Sori, a planetary scientist at Purdue University. “It was just such a perfect match, as good as you can ask for.”

From caps to craters

Previously, Martian climate scientists have focused on polar ice caps, which span hundreds of kilometers. But these deposits are old and may have lost ice over time, losing fine details that are necessary to confidently establish connections between the planet’s orientation and motion and its climate.

Sori and his colleagues turned to ice mounds in craters, just tens of kilometers wide but much fresher and potentially less complicated. After scouring much of the southern hemisphere, they pinpointed Burroughs crater, 74 kilometers wide, that has “exceptionally well-preserved” layers visible from NASA HiRISE imagery, Sori said.

The researchers analyzed the layers’ thicknesses and shapes and found they had strikingly similar patterns to two important Martian orbital dynamics, the tilt of Mars’ axis and orbital precession, over the last 4 to 5 million years.

The findings improve on previous research, which used Mars’ polar ice records of climate to establish tentative connections to orbit. But those records were too “noisy,” or complicated, to confidently connect the two. Younger, cleaner crater ice preserves less complicated climate records, which the researchers used to match climate changes to orbital precession and tilt with a high level of precision.

Mars as a natural lab

Discerning the connections between orbital cycles and climate is important for understanding both Martian history and complex climate dynamics on Earth. “Mars is a natural laboratory for studying orbital controls on climate,” Sori said, because many of the complicating factors that exist on Earth — biology, tectonics — are negligible on Mars. The whole planet, in essence, isolates the variable for scientists.

“If we’re ever going to understand climate, we need to go to places that don’t have these interfering factors,” said Isaac Smith, a planetary scientist at the Planetary Science Institute and York University who was not involved in the study. In that sense, “Mars is a pristine planet. And there are a lot of potential applications here. Mars has a lot more in common with Pluto and Triton than you think.”

Not all smaller ice deposits have clean, exposed layers at their surface. Some might be hidden inside the mounds. Eventually, Sori said, the goal is to sample ice cores like scientists do on Earth, but Mars rovers don’t have that capability yet. Instead, scientists can use ground-penetrating radar data to “peer inside” the ice and check for layers, making sure visible layers extend throughout the deposit. It’s a necessary quality-control step in the present study, and the method may help future explorations of Martian ice without layers visible at the surface.

“Being able to pull a climate signal from a small ice deposit is a really cool result,” said Riley McGlasson, a study co-author from Purdue University who applied this method in the new study. “With radar, we can get closer to the full story. That’s why I’m excited to take this a step further in the future.”

Story Source:

Materials provided by American Geophysical Union. Note: Content may be edited for style and length.

Journal Reference:

Michael M. Sori, Patricio Becerra, Jonathan Bapst, Shane Byrne, Riley A. McGlasson. Orbital Forcing of Martian Climate Revealed in a South Polar Outlier Ice Deposit. Geophysical Research Letters, 2022; 49 (6) DOI: 10.1029/2021GL097450

New ‘crime scene investigation’ may save endangered carnivorous plants

ENVIRONMENT

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01/04/2022

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New ‘crime scene investigation’ may save endangered carnivorous plants

Researchers have combined macro photography with DNA metabarcoding to create a new botanical “CSI” tool that may hold the key to safeguarding the future of Australia’s critically endangered carnivorous plants.

The new technology — developed by researchers from Curtin University, the Botanical and Zoological Natural History Collections in Munich and the University of Munich — enables experts to take a sophisticated look inside the stomachs of carnivorous plants, overcoming a hurdle that had previously stumped entomologists.

Researchers set off on a 6,000km journey to Western Australia’s remote Kimberley region to test the new method, capturing macro photographs of carnivorous plants of the genus Drosera, known as sundews.

Lead author Mr Thilo Krueger, a PhD student from Curtin’s School of Molecular and Life Sciences, said understanding how many and what kinds of insects that carnivorous plants ate was critical to their survival.

“Western Australia has — by far — the highest number of carnivorous plant species in the world and many of them are critically endangered, threatened by habitat destruction, environmental pollution and climate change,” Mr Krueger said.

“Quite often, several carnivorous plant species are found in one habitat, and the question arises if different species may rely upon different food sources. To develop conservation plans that protect their future, it is essential to understand their biology, which includes what they eat — their natural prey spectra.

“Studying the prey spectra of carnivorous plants has previously been hampered by the fact that digested insect prey is often hard to identify, even by trained entomologists. Soft-bodied insects such as midges often turn into unidentifiable crumbs during digestion on the leaves.”

Co-author Dr Adam Cross, a Botanist and Restoration Ecologist from Curtin’s School of Molecular and Life Sciences, said the new method combined macro photography of the captured insects with DNA metabarcoding, a cutting-edge insect identification tool.

“Any insect that is captured by a carnivorous plant will contain traces of its genetic material or DNA, even after digestion by the plant. This DNA can be detected and compared with DNA libraries of known insects, thus identifying the prey,” Dr Cross said.

“Because DNA metabarcoding is prone to contaminations and does not allow us to estimate the quantity of prey, we carefully controlled our data using macro photographs of the prey items to achieve an unprecedented completeness of prey spectra data.”

Senior author Dr Andreas Fleischmann, from the Botanical Natural History Collection and the University of Munich, said this new method of DNA metabarcoding was so sensitive that it even detected tiny amounts of insect DNA that were not obvious to researchers from field examination and macro photographs.

“Hence, our study of carnivorous prey spectra using genetic DNA fingerprints from the captured insects resembled reconstructing a crime scene — except our crime scene investigation was about finding out what a set of carnivorous plants had for lunch,” Dr Fleischmann said.

Story Source:

Materials provided by Curtin University. Note: Content may be edited for style and length.

Journal Reference:

Thilo Krueger, Adam T. Cross, Jeremy Hübner, Jérôme Morinière, Axel Hausmann, Andreas Fleischmann. A novel approach for reliable qualitative and quantitative prey spectra identification of carnivorous plants combining DNA metabarcoding and macro photography. Scientific Reports, 2022; 12 (1) DOI: 10.1038/s41598-022-08580-8

Tonga Eruption

VOLCANOES

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01/04/2022

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On January 15, the volcano Hunga Tonga-Hunga Ha’apai devastated the nation of Tonga. The eruption triggered tsunamis as far afield as the Caribbean and generated atmospheric waves that travelled around the globe several times. Meanwhile, the volcano’s plume shot gas and ash through the stratosphere into the lower mesosphere.

Just two months after the eruption, geologists have put together a preliminary account of how it unfolded. UC Santa Barbara’s Melissa Scruggs and emeritus Professor Frank Spera were part of an international team of researchers that published the first holistic account of the event in the journal Earthquake Research Advances. The authors think that an eruption the day before may have primed the volcano for the violent explosion by sinking its main vent below the ocean’s surface. This enabled molten rock to vaporize a large volume of seawater, intensifying the volcanic eruption the very next day.

“This is definitely, without a doubt, the largest eruption since Mt. Pinatubo in 1991,” said corresponding author Scruggs, who studies magma mixing and eruption triggering mechanisms, and recently completed her doctorate at UC Santa Barbara. She compared January’s event to the 1883 eruption of Krakatoa, which was heard 3,000 miles away.

Hunga Tonga-Hunga Ha’apai (HTHH) is a stratovolcano: a large, cone-shaped mountain that is prone to periodic violent eruptions, but which usually experiences milder activity. It’s one of many along the Tofua Volcanic Arc, a line of volcanoes fed by magma from the Pacific Plate diving beneath the Indo-Australian Plate. Heat and pressure cook the rocks of the descending plate, driving out water and other volatiles. That same water decreases the melting temperature of the rock above, leading to a chain of volcanoes about 100 kilometers from the plate boundary.

A submerged danger

The islands of Hunga Tonga and Hunga Ha’apai — after which the volcano is named — are merely the two highest points along the rim of the caldera, or central crater. Or they were, until the eruption blew most of the islands sky high.

Scruggs first heard about the eruption as she scrolled through her Twitter feed while getting ready for bed. “I saw a GIF of the satellite eruption, and my heart just stopped,” she said, pausing to find her words. She immediately knew that the event would cause massive devastation. “The scariest part was that the entire country was cut off, and we didn’t know what had happened.”

She was already messaging other volcanologists as the events unfolded, trying to understand the images that satellites had so clearly captured. “We really just set out to try to understand what happened,” Scruggs said. “So, we gathered all the information that we could, anything that was available within the first few weeks.” The authors drew on whatever resources they could find to quickly characterize this eruption, including publicly available data, videos and even tweets.

Using a variety of data sets, the team calculated that the January 15 event began at 5:02 p.m. local time (0402 ±1 UTC). The U.S. Geological Survey recorded a seismic event around 13 minutes later at the vent location. The first two hours of the eruption were particularly violent, with activity fading after about 12 hours.

But eruption activity had actually started all the way back on December 20, 2021. And before that, the volcano had erupted in 2009 and again in 2014 and 2015. Scruggs believes these earlier episodes are key to understanding the violence behind HTHH’s recent eruption, perhaps related to changes in the magma plumbing system at depth or the chemistry of the magma over time.

Hunga Tonga and Hunga Ha’apai used to be separate islands until they were united by eruptions from the volcano’s main vent, which created a land bridge. “This island was just born in 2015,” said Scruggs. “And now it’s gone. Were it not for the satellite era, we would not have even known it ever existed.”

On January 14, 2022 an explosion from the main vent razed this connection, sinking the vent beneath the ocean’s surface. “Had that land bridge not been taken out, the January 15 eruption might have behaved just like the day before because it would not have had that excess seawater,” Scruggs remarked.

A staggering explosion

Same volcano, one day’s difference: On Friday the vent was above the water, and by Saturday it was below. “That made all of the difference in the world,” Scruggs said.

The team believes that the seawater played a large part in the violence and force behind the Jan. 15 eruption. Much like a bottle rocket, an eruption of this scale takes the right ratio of water and gas to provide the force to send it skyward.

And it took off like a rocket, too. “It went halfway to space,” Scruggs exclaimed. The ash plume shot 58 kilometers into the atmosphere, past the stratosphere and into the lower mesosphere. This is more than twice the height reached by the plume from Mt. Saint Helens in 1980. It was the tallest volcanic plume ever recorded.

A truly staggering amount of lightning also accompanied the eruption. The authors suspect that vaporizing seawater caused the lava to fragment into microscopic ash particles, which were joined by tiny ice crystals once the steam froze in the upper atmosphere. The motion, temperature change and size of the particles generated incredible amounts of static charge separation that flashed above the eruption. For the first two hours of the eruption, about 80% of all lightning strikes on Earth split the sky above Hunga Tonga-Hunga Ha’apai.

The authors estimate around 1.9 km³ of material, weighing 2,900 teragrams, erupted from HTHH on Jan. 15. “But the volume of the eruption was not the big deal,” said Spera, a coauthor on the paper and Scruggs’ doctoral advisor. “What was special is how the energy of the eruption coupled to the atmosphere and oceans: A lot of the energy went into moving air and water on a global scale.”

The shockwave traveling through the ocean triggered tsunamis throughout the Pacific, and beyond. What’s more, the wave arrived faster than tsunami warning models predicted because the models aren’t calibrated for volcanic eruptions — they’re based on equations that describe tsunamis generated by earthquakes.

A second tsunami followed the atmospheric pressure wave. This shockwave even triggered a meteo-tsunami in the Caribbean, which has no direct connection to the South Pacific. Scruggs called it unprecedented: “Basically the whole ocean just kind of sloshed around for five days after the eruption,” she added.

Plenty of work to do

Scientists are still piecing together what happened at the volcano, so they have yet to develop a complete understanding of the tsunami wave. However, it’s an important task needed to update tsunami travel forecast systems so they account for this type of mechanism. Otherwise, warnings could be incorrect the next time a volcano like HTHH erupts, potentially costing more lives.

Indeed, the event highlights the danger posed by unmonitored submarine volcanoes. Despite the devastation, the people of Tonga were relatively well prepared for the Jan. 15 eruption. The government had issued warnings based on the previous day’s activity, and the nation had plans in place for eruptions and tsunamis.

HTHH has experienced similarly violent eruptions in the past. A recent paper by researchers at the University of Otago, New Zealand revealed that a large eruption destroyed the caldera at the summit of the undersea volcano about 1,000 years ago. And similar volcanoes could well erupt in the same manner. Consider Kick ‘em Jenny, another submarine volcano whose main vent is a mere 150 meters underwater. It’s located just 8 km north of the island of Grenada. “Imagine if something like the Tonga eruption happened in the Caribbean,” Scruggs said.

The researchers worked quickly with only publicly available data. They plan to revisit all their findings as more information and samples become available and as more researchers publish their own findings on this groundbreaking eruption. Their primary goal was to provide a point of departure for future work on the topic.

Scruggs is particularly keen on learning about the ash collected from this eruption. Volcanic rock provides a wealth of information to a trained geologist. Examining the material could shed light on the type of magma that erupted, how much of it there was and perhaps even how much seawater was involved in the eruption.

“There’s so many questions that have been raised,” said Scruggs. “Things we didn’t even think were possible have now been recorded.”

The UC Santa Barbara researchers will lead a special invited session on the Hunga Tonga-Hunga Ha’apai eruption at the Geological Society of America’s 2022 annual meeting in Denver this October. “It will be exciting to see what scores of other earth scientists can discover about this unique volcano,” Spera said. “We are just at the beginning.”

Increased heat and drought stunt tropical trees, a major carbon sink

ENVIRONMENT

contact.geology

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01/04/2022

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Increased heat and drought stunt tropical trees, a major carbon sink

For a long time, ecologists assumed tree rings to be absent in tropical trees because of a lack of temperature and rain fluctuations in the trees’ environment. But in recent decades, the formation of growth rings has been proven for hundreds of tropical tree species, which are sensitive to drought and usually experience at least a month or two of slightly reduced rainfall every year.

When scientists better understand how tropical trees respond to unusually dry and warm conditions, they can better predict how these trees will be affected by climate change.

A new study, co-authored by University of Arizona researchers and published in Nature Geoscience, has found that tropical trees’ trunk growth is reduced in years when the dry season is drier and warmer than normal. The study defines the tropics in a way that also includes the subtropics — or anything between 30 degrees north latitude and 30 degrees south latitude.

The researchers also found that the effect of drier and warmer years is more dramatic in more arid or warm regions in the tropics. This suggests that climate change may increase the sensitivity of tropical trees to climatic fluctuations. Temperatures at the study sites are expected to increase by half a degree Celsius per decade in the future.

The results of the study help explain the large fluctuations in carbon uptake by tropical vegetation globally. Model simulations show that during hotter or drier years, tropical vegetation grows less and therefore takes up less carbon dioxide from the atmosphere. But actual measurements of vegetation growth have been lacking until now.

Research shows that slower growth increases the risk of topical tree death, so tropical vegetation may more frequently become a source of carbon dioxide instead of absorbing this greenhouse gas that causes climate change.

“These (tropical) tree rings contain a wealth of information on the growth history of trees,” said lead study author Pieter Zuidema of Wageningen University & Research in the Netherlands. “In this study, we exploit that potential. For the first time, we get a pantropical picture of how tropical tree growth reacts to climate fluctuations.”

The study was an international collaborative effort that included University of Arizona dendrochronology Valerie Trouet, a professor in the Laboratory of Tree-Ring Research, and Flurin Babst, an assistant research professor in the UArizona School of Natural Resources and the Environment. The findings are based on a new global network, created by the collaborators, of over 14,000 tree-ring data series from 350 locations across 30 tropical and sub-tropical countries.

The authors were surprised to find that during the dry season, climate had a stronger effect on tree growth than during the wet season.

“We know that photosynthesis and wood production of tropical trees generally peak during the wet season,” Trouet said. “So, why do year-to-year fluctuations in trunk growth depend on the dry season? That surprised and puzzled us. Our explanation is that water is available for a longer period of time during years with wetter or cooler dry seasons. Put simply, the growing season is longer. This then leads to more trunk growth.”

The study also fills an important gap in tree-ring data.

“World maps showing the locations of tree-ring studies typically have a hole in the middle, in the tropics,” Zuidema said. “Our network fills that tropical data gap.”

The tree-ring data from more than 100 study locations has been uploaded to the International Tree-ring Databank, the global database for tree-ring data.

“In this way, the tree-ring data we’ve put together will be freely available for everyone,” Zuidema said.

Story Source:

Materials provided by University of Arizona. Note: Content may be edited for style and length.

Journal Reference:

Pieter A. Zuidema, Flurin Babst, Peter Groenendijk, Valerie Trouet, Abrham Abiyu, Rodolfo ro Venegas-González, Ricardo Villalba, Jose Villanueva-Diaz, Royd Vinya, Mart Vlam, Tommy Wils, Zhe-Kun Zhou. Tropical tree growth driven by dry-season climate variability. Nature Geoscience, 2022; DOI: 10.1038/s41561-022-00911-8