NASA tech breathes life into potentially game-changing antenna design

Oct. 27, 2023, by Swati Patel, NASA

https://phys.org/news/2023-10-nasa-tech-life-potentially-game-changing.html

FreeFall Tests Spherical Antennas at 159,000 feet on NASA’s 60 million cubic foot stratospheric balloon. 

Credit: Dr. Christopher Walker, NIAC Fellow / FreeFall Aerospace

Some 30 years ago, a young engineer named Christopher Walker was home in the evening making chocolate pudding when he got what turned out to be a very serendipitous call from his mother.

Taking the call, he shut off the stove and stretched plastic wrap over the pot to keep the pudding fresh. By the time he returned, the cooling air in the pot had drawn the wrap into a concave shape, and in that warped plastic, he saw something—the magnified reflection of an overhead lightbulb—that gave him an idea that could revolutionize space-based sensing and communications.

That idea became the Large Balloon Reflector (LBR), an inflatable device that creates wide collection apertures that weigh a fraction of today's deployable antennas. Now, with an assist from NASA's Innovative Advanced Concepts (NIAC) program, funded by the agency's Space Technology Mission Directorate, which supports visionary innovations from diverse sources, Walker's decades-old vision is coming to fruition.

The concept turns part of the inside surface of an inflated sphere into a parabolic antenna. A section comprising about a third of the balloon's interior surface is aluminized, giving it reflective properties.

With NIAC funding, and a grant from the U.S. Naval Research Laboratory, Walker was able to develop and demonstrate technologies for a 33-foot-diameter (10 meters) LBR that was carried to the stratosphere by a giant balloon. For comparison, the aperture of NASA's massive James Webb Space Telescope is over 21 feet (6.5 meters) in diameter.

https://youtu.be/Z4OQG4ABJ_k?si=eAQ9xCehc9g9cybu

"There was no place other than NIAC within NASA to get this off the ground," says Walker, now a astronomy and optical engineering professor at the University of Arizona in Tucson. "At first, I was afraid to share the idea with colleagues because it sounded so crazy. You need a program within NASA that will actually look at the radical ideas, and NIAC is it."

Parabolic dish antennas use their concave shape to capture and concentrate electromagnetic radiation. The larger the antenna's diameter, or aperture, the more effective it is for capturing light or radio waves and transmitting radio signals over great distances.

In astronomy, there is a tremendous advantage to placing telescopes above the Earth's atmosphere, which tends to distort or degrade signals coming from space. The challenge is that traditional large reflector antennas are heavy, unwieldy, and difficult to stow, leading to launch constraints and risky in-space deployment schemes.

The LBR design solves both problems. Made of a thin film structure, it inflates like a beachball, providing a stable parabolic-dish shape without the need for bulky and complex deployable hardware, and can fold into a tiny volume.

In 2018, Freefall Aerospace, a company co-founded by Walker to develop and market the technology, demonstrated the LBR's potential aboard NASA's stadium-sized stratospheric balloon, which carried a 3.28-foot scale model to an altitude of 159,000 feet.

STMD invested in the development of LBR through NASA NASA Innovative Advanced Concepts Program. 

Credit: NASA/BryceTech

Next up for the technology is a high-speed communications demonstration in low Earth orbit aboard a 6-unit CubeSat, about the size of a shoebox, called CatSat. It was selected for flight in 2019 as part of NASA's CubeSat Launch Initiative. It is a joint effort involving NASA, Freefall Aerospace, the University of Arizona, and Rincon Research Corporation in Tucson, Arizona.

After reaching low-Earth orbit, CatSat's inflatable antenna deployment system will deploy from its container, inflate to a diameter of about one-and-a-half feet, and begin transmitting back high-definition Earth photos. The mission is slated for launch with several other CubeSats on Firefly Aerospace's Alpha rocket as part of the Educational Launch of Nanosatellites (ELaNa) 43 mission.

A more ambitious lunar mission concept is also being explored. NASA's Goddard Space Flight Center in Greenbelt, Maryland, would use the inflatable antenna in tandem with a new instrument called Terahertz Spectrometer for In-Situ Resource Utilization, a miniature, high-power laser precisely calibrated to detect water, a critical exploration resource.

"The technology demonstrated by CatSat opens the door to the possibility of future lunar, planetary and deep-space missions using CubeSats," said Walker.

It might be difficult to believe this all started because a young engineer's idea of dinner one evening was what most would consider dessert. Then again, one could say the proof was in the pudding.

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Magnetic Mischief: Earth’s Upper Atmosphere and Satellite Communication Storms

By NAGOYA U. Oct. 30, 2023

https://scitechdaily.com/magnetic-mischief-earths-upper-atmosphere-and-satellite-communication-storms/

An international research study emphasizes the pivotal role of Earth’s upper atmosphere in the development of large geomagnetic storms. Previously, the significance of Earth’s atmosphere was undervalued. The research sheds light on how Earth’s ionospheric plasma contributes to geomagnetic storms alongside solar influences. Such storms can adversely impact the Earth’s magnetic field, affecting power grids, radio signals, and GPS systems.

Earth’s upper atmosphere plays a crucial role in shaping geomagnetic storms, with both solar and ionospheric plasma contributing to their development, according to a new study.

A new study has revealed the importance of the Earth’s upper atmosphere in determining how large geomagnetic storms develop. The research was conducted by an international team led by researchers from Nagoya University in Japan and the University of New Hampshire in the United States. Their findings reveal the previously underestimated importance of the Earth’s atmosphere.

Understanding the factors that cause geomagnetic storms is important because they can have a direct impact on the Earth’s magnetic field such as causing unwanted currents in the power grid and disrupting radio signals and GPS. This research may help predict the storms that will have the greatest consequences.

The Sun’s Role in Geomagnetic Storms

Scientists have long known that geomagnetic storms are associated with the activities of the Sun. Hot charged particles make up the Sun’s outer layer, the one visible to us. These particles flow out of the Sun creating the ‘solar wind’, and interact with objects in space, such as the Earth. When the particles reach the magnetic field surrounding our planet, known as the magnetosphere, they interact with it. The interactions between the charged particles and magnetic fields lead to space weather, the conditions in space that can affect the Earth, and technological systems such as satellites.

The importance of the Earth’s atmosphere in creating the large storms that affect satellite communications. 

Credit: ERG Science Team

Magnetotail and Its Importance

An important part of the magnetosphere is the magnetotail. The magnetotail is the part of the magnetosphere that extends away from the Sun, in the direction of the solar wind flow. Inside the magnetotail is the plasma sheet region, which is full of charged particles (plasma). The plasma sheet is important because it is the source region for the particles that get into the inner magnetosphere, creating the current that causes geomagnetic storms.

Research Focus and Findings

Although the importance of the Sun is well known, an international group of researchers aimed to solve the mystery of how much of the plasma in the magnetosphere comes from Earth and how that contribution changes during a geomagnetic storm. The group was led by Lynn Kistler, Nagoya University Designated Professor and University of New Hampshire Professor (cross-appointment), Yoshizumi Miyoshi, Nagoya University Professor, and Tomoaki Hori, Nagoya University Designated Professor.

For their study, they used data from a large geomagnetic storm that happened on September 7-8, 2017. During this time, the Sun released a massive coronal mass ejection that collided with the Earth’s atmosphere, resulting in a huge geomagnetic storm. The impact disrupted the magnetosphere, leading to interference with radio signals, GPS, and precision timing applications.

The researchers retrospectively analyzed the ion transport during this event using data from several space missions, including the NASA/Magnetospheric Multiscale (MMS) mission, the Japanese Arase mission, the ESA/Cluster mission, and the NASA/Wind mission. They distinguished the ions from those of the solar wind and from those of the ionosphere itself.

Using simultaneous measurements of the solar wind composition to track the source changes, they identified substantial changes in the composition and other properties of the near-earth plasma sheet as it developed. These properties of the plasma sheet, such as density, particle energy distribution, and composition, affect the development of the geomagnetic storm.

At the start of the main phase of the storm, the source changed from solar wind-dominated to ionosphere-dominated. “The most important discovery was that at the beginning of the geomagnetic storm, the plasma changed from mostly solar to mostly ionospheric,” explained Kistler. “This shows that the geomagnetic storm drives more outflow from the Earth’s ionosphere, and that the ionospheric plasma can move quickly throughout the magnetosphere.”

“Overall, our research contributes to understanding the development of geomagnetic storms by showing the importance of Earth’s ionospheric plasma,” she continues. “We found compelling evidence that plasmas from not only the Sun but also the Earth drive a geomagnetic storm. In short, the properties of the plasma sheet (the density, the particle energy distribution, the composition) will affect geomagnetic storms, and these properties are different for different sources.”

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Solar Spectacle: Highest-Energy Sunlight Ever Recorded Stuns Scientists

By MICHIGAN STATE U. Oct. 27, 2023

https://scitechdaily.com/solar-spectacle-highest-energy-sunlight-ever-recorded-stuns-scientists/

Researchers discovered the highest-energy light ever observed from the sun, known as gamma rays, which was brighter than previously anticipated. This finding, derived from six years of data, challenges previous understandings and raises questions about the sun’s processes and its magnetic fields.

Physicists have detected the most energetic light ever observed emanating from the sun.

Sometimes, the best place to hide a secret is in broad daylight. Just ask the sun.

“The sun is more surprising than we knew,” said Mehr Un Nisa, a postdoctoral research associate at Michigan State University. “We thought we had this star figured out, but that’s not the case.”

Nisa, who will soon be joining MSU’s faculty, is the corresponding author of a new paper in the journal Physical Review Letters that details the discovery of the highest-energy light ever observed from the sun.

The international team behind the discovery also found that this type of light, known as gamma rays, is surprisingly bright. That is, there’s more of it than scientists had previously anticipated.

Watching like a HAWC

Although the high-energy light doesn’t reach the Earth’s surface, these gamma rays create telltale signatures that were detected by Nisa and her colleagues working with the High-Altitude Water Cherenkov Observatory, or HAWC.

Funded by the National Science Foundation and the National Council of Humanities Science and Technology, HAWC is an important part of the story. Unlike other observatories, it works around the clock.

“We now have observational techniques that weren’t possible a few years ago,” said Nisa, who works in the Department of Physics and Astronomy in the College of Natural Science.

“In this particular energy regime, other ground-based telescopes couldn’t look at the sun because they only work at night,” she said. “Ours operates 24/7.”

In addition to working differently from conventional telescopes, HAWC looks a lot different from the typical telescope.

Rather than a tube outfitted with glass lenses, HAWC uses a network of 300 large water tanks, each filled with about 200 metric tons of water. The network is nestled between two dormant volcano peaks in Mexico, more than 13,000 feet above sea level.

From this vantage point, it can observe the aftermath of gamma rays striking air in the atmosphere. Such collisions create what are called air showers, which are a bit like particle explosions that are imperceptible to the naked eye.

The energy of the original gamma ray is liberated and redistributed amongst new fragments consisting of lower energy particles and light. It’s these particles — and the new particles they create on their way down — that HAWC can “see.”

When the shower particles interact with water in HAWC’s tanks, they create what’s known as Cherenkov radiation that can be detected with the observatory’s instruments.

Nisa and her colleagues began collecting data in 2015. In 2021, the team had accrued enough data to start examining the sun’s gamma rays with sufficient scrutiny.

“After looking at six years’ worth of data, out popped this excess of gamma rays,” Nisa said. “When we first saw it, we were like, ‘We definitely messed this up. The sun cannot be this bright at these energies.’”

Making history

The sun gives off a lot of light spanning a range of energies, but some energies are more abundant than others.

For example, through its nuclear reactions, the sun provides a ton of visible light — that is, the light we see. This form of light carries an energy of about 1 electron volt, which is a handy unit of measure in physics.

The gamma rays that Nisa and her colleagues observed had about 1 trillion electron volts, or 1 tera electron volt, abbreviated 1 TeV. Not only was this energy level surprising but so was the fact that they were seeing so much of it.

In the 1990s, scientists predicted that the sun could produce gamma rays when high-energy cosmic rays — particles accelerated by a cosmic powerhouse like a black hole or supernova — smash into protons in the sun. But, based on what was known about cosmic rays and the sun, the researchers also hypothesized it would be rare to see these gamma rays reach Earth.

At the time, though, there wasn’t an instrument capable of detecting such high-energy gamma rays and there wouldn’t be for a while. The first observation of gamma rays with energies of more than a billion electron volts came from NASA’s Fermi Gamma-ray Space Telescope in 2011.

Over the next several years, the Fermi mission showed that not only could these rays be very energetic, but also that there were about seven times more of them than scientists had originally expected. And it looked like there were gamma rays left to discover at even higher energies.

When a telescope launches into space, there’s a limit to how big and powerful its detectors can be. The Fermi telescope’s measurements of the sun’s gamma rays maxed out around 200 billion electron volts.

Theorists led by John Beacom and Annika Peter, both professors at Ohio State University, encouraged the HAWC Collaboration to take a look.

“They nudged us and said, ‘We’re not seeing a cutoff. You might be able to see something,” Nisa said.

The HAWC Collaboration includes more than 30 institutions across North America, Europe, and Asia, and a sizable portion of that is represented in the nearly 100 authors on the new paper. That includes three additional Spartans: graduate student Daniel Salazar-Gallegos, Professor Emeritus James Linnemann, and Kirsten Tollefson, a professor of physics and astronomy and associate dean in the Graduate School at MSU.

Now, for the first time, the team has shown that the energies of the sun’s rays extend into the TeV range, up to nearly 10 TeV, which does appear to be the maximum, Nisa said.

Currently, the discovery creates more questions than answers. Solar scientists will now scratch their heads over how exactly these gamma rays achieve such high energies and what role the sun’s magnetic fields play in this phenomenon, Nisa said.

When it comes to the cosmos, though, that’s part of the excitement. It tells us that there was something wrong, missing, or perhaps both when it comes to how we understand our nearest and dearest star.

“This shows that HAWC is adding to our knowledge of our galaxy at the highest energies, and it’s opening up questions about our very own sun,” Nisa said. “It’s making us see things in a different light. Literally.”

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Defense News: How the IDF is turning guerilla warfare against Hamas in Gaza - analysis

 

How the IDF is turning guerilla warfare against Hamas in Gaza - analysis

Guerilla warfare is almost as old as war, but traditionally it was used by the little/weaker side to hold off the larger/less agile side.

By YONAH JEREMY BOB, Jerusalem Post, OCTOBER 27, 2023

https://www.jpost.com/arab-israeli-conflict/article-770513

A Lebanese Hezbollah guerrilla looks at a fire rising from a burning object in a Beirut suburb, Lebanon July 17, 2006. (photo credit: REUTERS/ISSAM KOBEISI/FILE PHOTO)

The IDF invasion of Gaza has begun, you just did not hear about it, or heard about it but could not tell.

In the last couple of days, the IDF initiated three targeted and short incursions into Gaza, before withdrawing each time.

Two of the incursions were by land and a third was by sea by Shayetet 13 naval commandos.

You did not hear about it or it did not register as significant because, tactically speaking, all each incursion did was destroy a limited number of Hamas infrastructure targets and engage a small number of peripheral Gaza fighters.

Prior airstrikes for three weeks have done far more damage, so the impact was pretty limited.

A joint drill between the IDF’s elite Shayetet 13 navy commandos and US Army Special Forces (credit: IDF SPOKESPERSON'S UNIT)

The media also has not been impressed with these small incursions because the expectations had been set for three weeks of a massive ground assault – the largest ever into Gaza - drawing on the 360,000 IDF reservists who were called up.

What has happened has been minuscule compared to that and still has not even reached the 2014 Gaza war invasion level, which itself was limited.

There are important questions about whether delaying the invasion until now was the right move. Also, there are questions about whether the rest of the large-scale invasion will be delayed beyond a point where world pressure on Israel to end the war escalates.

But assuming the rest of the large-scale invasion happens in the relatively near future, the concept of rolling out the invasion in steps, starting with a variety of surprise and fast “in and out” moves is sound and even smart.

Some analysts thought this process had even started two weeks ago, only to learn a day or two later that reported incursions into Gaza back at that time, were just barely over the border to gather bodies and did not even involve really engaging Hamas.

Essentially, the IDF is turning guerilla warfare tactics on Hamas.

Soldiers of the IDF Golani brigade train for possible combat during Operation Swords of Iron, October 2023 (photo credit: IDF)

Turning guerrilla warfare on Hamas

Hamas’ only chance to survive at this point is to bog Israel down with ambushes, boobytraps, and hit-and-run-style attacks deep in Gaza’s cities so as to neutralize Israel’s aerial and other technological advantages.

Smartly, the IDF is not just taking the bait.

Guerilla warfare is almost as old as war, but traditionally it was used by the little/weaker side to hold off the larger/less agile side.

Since terrorists, whether against Israel or the US, started systematically employing guerilla warfare and human shields in urban settings, Washington, and sometimes Jerusalem, have started to figure out that being the larger and more powerful force does not mean needing to give up being agile and using the element of surprise.

By making targeted incursions and regularly changing the spots where the incursions take place, the IDF is keeping Hamas on edge.

Put simply, Gaza’s terror rulers do not know where the IDF may jump out from next.

This is designed to make Hamas antsy to the point that it negatively impacts morale, to have it start second-guessing its defensive posture, enable the IDF drone and other surveillance platforms to observe Hamas movements adjusting that posture (which helps reveal some of its hiding places), and to get Hamas to prematurely activate boobytraps and ambushes without being able to maximize their impact on larger groups of IDF troops.

These guerilla warfare tactics, which are essentially the IDF’s own version of “hit and run” can also flip Hamas’ pre-October 7 game of luring Israel into complacency on its head.

True, Hamas is disciplined and may be able to see through a number of small incursions while maintaining readiness for the later large invasion, but it is only natural that some of its readiness will go down, as Hamas fighters get used to the incursions as being minor and “false alarms” compared to the grand invasion.

If the IDF applies the tactic properly, it will start making multiple targeted short incursions at the same time with a high enough frequency that Hamas will become more and more confused about what will happen next, about when an incursion might be larger, from where it will come – and then strike at that moment when Hamas’ guard has suddenly gone down.

This will enable the IDF to get an initial foothold in Gaza with larger troops before Hamas can fully adjust and mount a counter-offensive.

None of this means that the IDF can avoid significant casualties.

At some point, troops will need to exit their armored personnel carriers and go house to house, street corner by street corner, to root out terrorists hiding in tunnels, attics, and anywhere else small that drones and technological platforms may miss without boots on the ground up close.

Hamas will then get its chance to blow up IDF troops when they open a house door, to gun them down through hidden small holes in walls for just a tiny and impossible-to-see part of the nozzle firing part of a gun to slide through and to fire anti-tank missiles on IDF vehicles which are bogged down in an area set up for a crossfire ambush.

But fighting guerilla warfare with guerilla warfare shows respect for the adversary, forces IDF forces to maintain a greater agility and operational awareness, improves intelligence understanding of Hamas’ defensive posture, and should at least improve IDF morale at the initial stages of the invasion.

In short, the initial limited incursions are by no means a basis to significantly delay or replace a larger invasion. But when used properly, it can enhance the chances of the invasion’s success substantially.

 Israeli soldiers at a staging area near the Israeli-Gaza border, October 24, 2023

(photo credit: YONATAN SINDEL/FLASH90)

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Light Years Ahead: NIST’s 400,000-Pixel Superconducting Camera Breakthrough

By NAT. INST. OF STANDARDS AND TECH. (NIST), OCTOBER 26, 2023

https://scitechdaily.com/light-years-ahead-nists-400000-pixel-superconducting-camera-breakthrough/

With planned improvements, NIST’s new 400,000 single-wire superconducting camera, the highest resolution camera of its type, will have the capability to capture astronomical images under extremely low-light-level conditions. 

Credit: Image incorporates elements from Pixabay and S. Kelley/NIST

Having more pixels could advance everything from biomedical imaging to astronomical observations.

Researchers at the National Institute of Standards and Technology (NIST) and their colleagues have built a superconducting camera containing 400,000 pixels — 400 times more than any other device of its type.

Superconducting cameras allow scientists to capture very weak light signals, whether from distant objects in space or parts of the human brain. Having more pixels could open up many new applications in science and biomedical research.

How It Works

The NIST camera is made up of grids of ultrathin electrical wires, cooled to near absolute zero, in which current moves with no resistance until a wire is struck by a photon. In these superconducting nanowire cameras, the energy imparted by even a single photon can be detected because it shuts down the superconductivity at a particular location (pixel) on the grid. Combining all the locations and intensities of all the photons makes up an image.

https://youtu.be/R1hG7GzjHyI?si=s-rH2v2eIvL15rA0

This animation depicts the special readout system that made it possible for NIST researchers to build a 400,000 superconducting-nanowire single-photon camera, the highest resolution camera of its type. With further improvements, the camera will be ideal for such low-light endeavors as imaging faint galaxies or planets that lie beyond the solar system, measuring light in photon-based quantum computers, and biomedical studies that use near-infrared light to peer into human tissue. Credit: S. Kelley/NIST

Evolution of Superconducting Cameras

The first superconducting cameras capable of detecting single photons were developed more than two decades ago. Since then, the devices have contained no more than a few thousand pixels — too limited for most applications.

Creating a superconducting camera with a greater number of pixels has posed a serious challenge because it would become all but impossible to connect every single chilled pixel among many thousands to its own readout wire. The challenge stems from the fact that each of the camera’s superconducting components must be cooled to ultralow temperatures to function properly, and individually connecting every pixel among millions to the cooling system would be virtually impossible.
Innovative Solution

NIST researchers Adam McCaughan and Bakhrom Oripov and their collaborators at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, and the University of Colorado Boulder overcame that obstacle by combining the signals from many pixels onto just a few room-temperature readout wires.

A general property of any superconducting wire is that it allows current to flow freely up to a certain maximum “critical” current. To take advantage of that behavior, the researchers applied a current just below the maximum to the sensors. Under that condition, if even a single photon strikes a pixel, it destroys the superconductivity. The current is no longer able to flow without resistance through the nanowire and is instead shunted to a small resistive heating element connected to each pixel. The shunted current creates an electrical signal that can rapidly be detected.

Borrowing Existing Technology

Borrowing from existing technology, the NIST team constructed the camera to have intersecting arrays of superconducting nanowires that form multiple rows and columns, like those in a tic-tac-toe game. Each pixel — a tiny region centered on the point where individual vertical and horizontal nanowires cross — is uniquely defined by the row and column in which it lies.

That arrangement enabled the team to measure the signals coming from an entire row or column of pixels at a time rather than recording data from each individual pixel, drastically reducing the number of readout wires. To do so, the researchers placed a superconducting readout wire parallel to but not touching the rows of pixels, and another wire parallel but not touching the columns.

Consider just the superconducting readout wire parallel to the rows. When a photon strikes a pixel, the current shunted into the resistive heating element warms a small part of the readout wire, creating a tiny hotspot. The hotspot, in turn, generates two voltage pulses traveling in opposite directions along the readout wire, which are recorded by detectors at either end. The difference in time it takes for the pulses to arrive at the end detectors reveals the column in which the pixel resides. A second superconducting readout wire that lies parallel to the columns serves a similar function.

The detectors can discern differences in arrival time of signals as short as 50 trillionths of a second. They can also count up to 100,000 photons a second striking the grid.

Future Prospects

Once the team adopted the new readout architecture, Oripov made rapid progress in increasing the number of pixels. Over a matter of weeks, the number jumped from 20,000 to 400,000 pixels. The readout technology can easily be scaled up for even larger cameras, said McCaughan, and a superconducting single-photon camera with tens or hundreds of millions of pixels could soon be available.

Over the next year, the team plans to improve the sensitivity of the prototype camera so that it can capture virtually every incoming photon. That will enable the camera to tackle such low-light endeavors as imaging faint galaxies or planets that lie beyond the solar system, measuring light in photon-based quantum computers, and contributing to biomedical studies that use near-infrared light to peer into human tissue.

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Study suggests climate change likely impacted human populations in the Neolithic and Bronze Age

OCTOBER 25, 2023, by Public Library of Science

https://phys.org/news/2023-10-climate-impacted-human-populations-neolithic.html

The Schneiderberg near Baalberge (Saxony-Anhalt, Germany) is a burial mound built in the Neolithic period which was enlarged several times. One extension took place around 2000 BCE and contained a strikingly richly furnished burial. It is one of a whole series of burials of this kind in the region around the Harz Mountains, dating from a period of unfavorable climatic conditions. The linking of data on demographic development with regional climate data and actual archaeological finds in the study provides new insights into the interconnectedness of climate fluctuations and social changes in Central Europe between 5,500 and 3,500 years ago. 

Credit: Johannes Müller, CC-BY 4.0 (creativecommons.org/licenses/by/4.0/)

Human populations in Neolithic Europe fluctuated with changing climates, according to a study published October 25, 2023 in the open-access journal PLOS ONE by Ralph Großmann of Kiel University, Germany and colleagues.

The archaeological record is a valuable resource for exploring the relationship between humans and the environment, particularly how each is affected by the other. In this study, researchers examined Central European regions rich in archaeological remains and geologic sources of climate data, using these resources to identify correlations between human population trends and climate change.

The three regions examined are the Circumharz region of central Germany, the Czech Republic/Lower Austria region, and the Northern Alpine Foreland of southern Germany.

Researchers compiled over 3,400 published radiocarbon dates from archaeological sites in these regions to serve as indicators of ancient populations, following the logic that more dates are available from larger populations leaving behind more materials. Climate data came from cave formations in these regions which provide datable information about ancient climate conditions. These data span 3550–1550 BC, from the Late Neolithic to the Early Bronze Age.

The study found a notable correlation between climate and human populations. During warm and wet times, populations tended to increase, likely bolstered by improved crops and economies. During cold and dry times, populations often decreased, sometimes experiencing major cultural shifts with potential evidence of increasing social inequality, such as the emergence of high status "princely burials" of some individuals in the Circumharz region.

These results suggest that at least some of the trends in human populations over time can be attributed to the effects of changing climates. The authors acknowledge that these data are susceptible to skewing by limitations of the archaeological record in these regions, and that more data will be important to support these results. This type of study is crucial for understanding human connectivity to the environment and the impacts of changing climates on human cultures.

The authors add, "Between 5,500 and 3,500 years ago, climate was a major factor in population development in the regions around the Harz Mountains, in the northern Alpine foreland and in the region of what is now the Czech Republic and Austria. However, not only the population size, but also the social structures changed with climate fluctuations."

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Space News: Discovery of molten layer covering Mars may explain why Martians don't exist

 

Discovery of molten layer covering Mars may explain why Martians don't exist

Researchers say their latest analysis shows the difference between Earth and Mars' internal structures - and could explain why there is life on one and not the other.

By Jake Levison, Sky News reporter, Wednesday 25 October 2023

https://news.sky.com/story/new-analysis-of-mars-may-explain-why-martians-dont-exist-12992408

An artist's depiction of the liquid silicate layer wrapped around the Martian core. Pic: IPGP-CNES

A liquid silicate "blanket" wrapped around the core of Mars gives us new clues about the planet's history and why it is devoid of life, researchers have said.

Findings from a paper published today in the journal Nature provide insights into how Mars formed, evolved and became the barren planet it is now, according to an international team of researchers.

NASA's InSight mission to Mars launched in 2018 and has helped scientists map out the planet's internal structure, including the size and composition of its core, and provided general hints about its tumultuous formation.

The mission officially ended in December 2022 after more than four years of collecting Mars data, but analysis of its observations continues.

The findings published today, which cast doubts on the first estimates of the Red Planet, are from the analysis of a powerful meteorite impact observed by the InSight mission that occurred in September 2021.

Image:An undated NASA image of Mars

The journal details the use of seismic data to locate and identify a thin layer of molten silicates - rock-forming minerals that make up the crust and mantle of Mars and Earth - lying between the Martian mantle and core.

With the discovery of this molten layer, the researchers determined that Mars' core is both denser and smaller than previous estimates, a conclusion that better aligns with other geophysical data and analysis of Martian meteorites.

Molten layer is like a 'heating blanket'

Vedran Lekic, a professor of geology at the University of Maryland and co-author of the paper, compared the molten layer to a "heating blanket" covering the Martian core.

"The blanket not only insulates the heat coming from the core and prevents the core from cooling, but also concentrates radioactive elements whose decay generates heat," he said.

"And when that happens, the core is likely to be unable to produce the convective motions that would create a magnetic field - which can explain why Mars currently doesn't have an active magnetic field around it."

Why is there no life on Mars?

Without that functional protective magnetic field around itself, a terrestrial planet such as Mars would be extremely vulnerable to harsh solar winds and lose all the water on its surface, making it incapable of sustaining life, Prof Lekic said.

He added that the difference between Earth and Mars' internal structures could explain why there is life on one and not the other.

The paper's lead author, Henri Samuel, a scientist with the French National Centre for Scientific Research, said: "The thermal blanketing of Mars' metallic core by the liquid layer at the base of the mantle implies that external sources are necessary to generate the magnetic field recorded in the Martian crust during the first 500 to 800 million years of its evolution.

"These sources could be energetic impacts or core motion generated by gravitational interactions with ancient satellites which have since then disappeared."

'Paving the way for future missions'

The team said their conclusions support theories that Mars was at one time a molten ocean of magma that later crystallised to produce a layer of silicate melt enriched in iron and radioactive elements at the base of the Martian mantle.

The heat emanating from the radioactive elements would then have dramatically altered the thermal evolution and cooling history of the red planet, according to the paper.

"These layers, if widespread, can have pretty big consequences for the rest of the planet," Prof Lekic said.

"Their existence can help tell us whether magnetic fields can be generated and maintained, how planets cool over time, and also how the dynamics of their interiors change over time."

"This new discovery of a molten layer is just one example of how we continue to learn new things from the completed InSight mission.

"We hope that the information we've gathered on planetary evolution using seismic data is paving the way for future missions to celestial bodies like the moon and other planets like Venus."

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Technology News: Bitcoin mining consumes more electricity than most countries, study suggests

 

Bitcoin mining consumes more electricity than most countries, study suggests

To offset the carbon footprint of mining the leading cryptocurrency, a UN report has said more than 3.9 billion trees would need to be planted.

By Sky News, Tuesday 24 October 2023

https://news.sky.com/story/bitcoin-mining-consumes-more-electricity-than-most-countries-study-suggests-12991456

Bitcoin mining consumes more electricity than most countries, according to a new report on its damaging environmental impact.

Mining is the process by which transactions are added to and validated on the blockchain, the public ledger for cryptocurrencies.

Competing miners race to use computers to solve complex mathematical puzzles using extremely powerful hardware - receiving new Bitcoin as a reward for their efforts.

In 2020 to 2021, Bitcoin consumed 173.42 terawatt hours of electricity - enough to rank it 27th among nations, trumping the likes of Pakistan with a population of over 230 million people.

The resulting carbon footprint was the equivalent of burning 84 billion pounds of coal.

To offset this, a study by the United Nations University found 3.9 billion trees would have to be planted, covering an area almost equal to the Netherlands, Switzerland, or Denmark.

Professor Kaveh Madani said: "Technological innovations are often associated with unintended consequences.

"Bitcoin is no exception."

What powers mining - and which countries lead the way?

The UN team's research, published in the journal Earth's Future, found Bitcoin mining relies heavily on fossil fuels.

Coal made up 45% of its supply mix during this period, followed by natural gas on 21%.

Renewables like solar and wind provided a comparably tiny proportion of the electricity mining uses between 2020 and 2021.

But organisations including the Bitcoin Mining Council - which represents 43% of miners around the world - claim this energy-intensive process has become more eco-friendly since.

Its figures suggest 59.9% of the electricity used by its members came from sustainable sources in the first six months of 2023. However, these figures are difficult to verify, and only represent less than half of the overall network.

At the time of the UN study in 2021, China was by far the biggest Bitcoin mining nation - but it has since been overtaken by the US after Beijing launched an aggressive clampdown on the practice.

Combined, the 10 countries that mined the most Bitcoin were responsible for 92% of the climate footprint.

Image:Countries ranked by how much electricity their Bitcoin mining operations used in 2020-21

"Our findings should not discourage the use of digital currencies," Prof Madani added.

"Instead, they should encourage us to invest in regulatory interventions and technological advancements that improve the efficiency of the global financial system without harming the environment."

Are there alternatives?

Some blockchains have already moved away from mining in favour of greener alternatives.

The Ethereum network - the second-largest after Bitcoin - made miners obsolete in September 2022 after an ambitious upgrade.

Instead, new transactions are approved by people who voluntarily lock up their cryptocurrency - and according to the Ethereum Foundation, this approach uses 99% less energy.

Greenpeace has lobbied for Bitcoin miners to follow suit, but its pleas have fallen on deaf ears.

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