среда, 13 февраля 2019 г.

New research suggests life thrived on Earth 3.5 billion years ago

Three and a half billion years ago Earth hosted life, but was it barely surviving, or thriving? A new study carried out by a multi institutional team with leadership including the Earth-Life Science Institute (ELSI) of Tokyo Institute of Technology (Tokyo Tech) provides new answers to this question. Microbial metabolism is recorded in billions of years of sulfur isotope ratios that agree with this study’s predictions, suggesting life throve in the ancient oceans. Using this data, scientists can more deeply link the geochemical record with cellular states and ecology.

New research suggests life thrived on Earth 3.5 billion years ago
Electron microscopy image of microbial cells which respire sulfate
[Credit: Guy Perkins and Mark Ellisman, National Center for
 Microscopy and Imaging Research]

Scientists want to know how long life has existed on Earth. If it has been around for almost as long as the planet, this suggests it is easy for life to originate and life should be common in the Universe. If it takes a long time to originate, this suggests there were very special conditions that had to occur. Dinosaurs, whose bones are presented in museums around the world, were preceded by billions of years by microbes. While microbes have left some physical evidence of their presence in the ancient geological record, they do not fossilize well, thus scientists use other methods for understanding whether life was present in the geological record.
Presently, the oldest evidence of microbial life on Earth comes to us in the form of stable isotopes. The chemical elements charted on the periodic are defined by the number of protons in their nuclei, for example, hydrogen atoms have one proton, helium atoms have two, carbon atoms contain six. In addition to protons, most atomic nuclei also contain neutrons, which are about as heavy as protons, but which don’t bear an electric charge.

Atoms which contain the same number of protons, but variable numbers of neutrons are known as isotopes. While many isotopes are radioactive and thus decay into other elements, some do not undergo such reactions; these are known as “stable” isotopes. For example, the stable isotopes of carbon include carbon 12 (written as 12C for short, with 6 protons and 6 neutrons) and carbon 13 (13C, with 6 protons and 7 neutrons).

New research suggests life thrived on Earth 3.5 billion years ago
Sulfide is formed by microbes which use sulfate in their energy metabolism, and this can be trapped for billions of years
 in iron sulfide minerals like those of the FeS2 mineral pyrite in the photo. New research by Sim and colleagues shows
the importance of an individual cellular enzyme in controlling the final mixture of sulfur isotopes in these minerals,
in turn linking biochemistry, cell physiology, and the record of life on planet Earth
[Credit: Yuichiro Ueno, ELSI]

All living things, including humans, “eat and excrete.” That is to say, they take in food and expel waste. Microbes often eat simple compounds made available by the environment. For example, some are able to take in carbon dioxide (CO2) as a carbon source to build their own cells. Naturally occurring CO2 has a fairly constant ratio of 12C to 13C.

However, 12CO2 is about 2 % lighter than 13CO2, so 12CO2 molecules diffuse and react slightly faster, and thus the microbes themselves become “isotopically light,” containing more 12C than 13C, and when they die and leave their remains in the fossil record, their stable isotopic signature remains, and is measurable. The isotopic composition, or “signature,” of such processes can be very specific to the microbes that produce them.

Besides carbon there are other chemical elements essential for living things. For example, sulfur, with 16 protons, has three naturally abundant stable isotopes, 32S (with 16 neutrons), 33S (with 17 neutrons) and 34S (with 18 neutrons). Sulfur isotope patterns left behind by microbes thus record the history of biological metabolism based on sulfur-containing compounds back to around 3.5 billion years ago.

Hundreds of previous studies have examined wide variations in ancient and contemporary sulfur isotope ratios resulting from sulfate (a naturally occurring sulfur compound bonded to four oxygen atoms) metabolism. Many microbes are able to use sulfate as a fuel, and in the process excrete sulfide, another sulfur compound. The sulfide “waste” of ancient microbial metabolism is then stored in the geological record, and its isotope ratios can be measured by analyzing minerals such as the FeS2 mineral pyrite.

New research suggests life thrived on Earth 3.5 billion years ago
McGlynn explains that the sulfur atom of the APS molecule is reduced by the Apr enzyme,
 leading to the kinetic isotope fractionation reported in the paper [Credit: ELSI]

This new study reveals a primary biological control step in microbial sulfur metabolism, and clarifies which cellular states lead to which types of sulfur isotope fractionation. This allows scientists to link metabolism to isotopes: by knowing how metabolism changes stable isotope ratios, scientists can predict the isotopic signature organisms should leave behind.
This study provides some of the first information regarding how robustly ancient life was metabolizing. Microbial sulfate metabolism is recorded in over a three billion years of sulfur isotope ratios that are in line with this study’s predictions, which suggest life was in fact thriving in the ancient oceans. This work opens up a new field of research, which ELSI Associate Professor Shawn McGlynn calls “evolutionary and isotopic enzymology.”

Using this type of data, scientists can now proceed to other elements, such as carbon and nitrogen, and more completely link the geochemical record with cellular states and ecology via an understanding of enzyme evolution and Earth history.

The research is published in Nature Communications.

Source: Tokyo Institute of Technology [February 08, 2019]



Chimpanzee brain organoids hint at secrets of human evolution

At some point during human evolution, a handful of genetic changes triggered a dramatic threefold expansion of the brain’s neocortex, the wrinkly outermost layer of brain tissue responsible for everything from language to self-awareness to abstract thought. Identifying what drove this evolutionary shift is fundamental to understanding what makes us human, but has been particularly challenging for scientists because of ethical prohibitions against studying the developing brains of our closest living relative, the chimpanzee, in the lab.

Chimpanzee brain organoids hint at secrets of human evolution
A chimpanzee (Pan troglodytes) mother nursing her baby in Tanzania’s Mahale Mountains National Park,
on the shores of Lake Tanganyika, where study co-author Alex Pollen was first inspired to study
human and chimpanzee brain evolution [Credit: Susan K. McConnell/Cell Press]

“By birth, the human cortex is already twice as large as in the chimpanzee, so we need to go back much earlier into embryonic development to understand the events that drive this incredible growth,” said Arnold Kriegstein, MD, Ph.D., the John Bowes Distinguished Professor in Stem Cell and Tissue Biology, founding director of the Eli and Edyth Broad Center of Regenerative Medicine and Stem Cell Research at UC San Francisco, and member of the UCSF Weill Institute for Neurosciences.

In a study published in Cell, Kriegstein and collaborators have gotten around this impasse by creating chimpanzee brain “organoids”—small clusters of brain cells grown from stem cells in a laboratory dish that mimic the development and organization of full-size brains.

Kriegstein’s group was among the early pioneers of growing human brain organoids from so-called induced pluripotent stem cells (iPSCs)—adult cells (usually skin cells) reprogrammed into stem cells that can become any tissue in the body. Organoids have since become a valuable tool for studying human tissue development and disease in a controlled laboratory setting, but the new study, in which the researchers generated 56 organoids from stem cells derived from the skin of eight chimpanzees and 10 humans, marks the first time researchers have been able to produce and study chimpanzee brain organoids en masse.

“Our ability to take skin cells from an adult chimpanzee, turn them into iPSCs, and then study their development in laboratory dishes is astounding,” said Kriegstein. “It’s a ‘science fiction’ experiment that couldn’t have happened 10 years ago.”

“These chimpanzee organoids give us an otherwise inaccessible window to six million years of our evolution. They let us ask new questions about what makes us human,” added study co–first author Alex Pollen, Ph.D., an assistant professor of neurology and former Kriegstein lab postdoctoral researcher, who led the development of the new great ape stem cell and organoid technology.

In the new study, co–first author Aparna Bhaduri, Ph.D., a postdoctoral researcher in the Kriegstein lab, deconstructed human and chimpanzee organoids at different stages of development, allowing her to directly compare the specific cell types and genetic programs that orchestrate the growth of the chimp and human brain.

Chimpanzee brain organoids hint at secrets of human evolution
The human (left) and chimpanzee (right) brain organoids contain multiple types of neural stem cells (red and green)
and mature brain cells (magenta and cyan), mimicking the development of real human and chimpanzee brains.
(Scale bar 100 micrometers) [Credit: Pollen and Kriegstein Labs/UCSF]

By looking for differences in gene activity between human organoids and chimp organoids (as well as reference tissue from another primate, the rhesus macaque monkey) Bhaduri identified several hundred genetic changes unique to the human lineage that could help explain the evolutionary origins of the distinctly human brain.

For instance, Bhaduri discovered that neural precursor cells called outer radial glia (oRG)—originally discovered by the Kriegstein lab—showed heightened activity of a key growth signaling network known as the mTOR pathway in human organoids.

The Kriegstein lab has been studying the potential role of oRGs in the expansion of the human cortex for nearly a decade, “so it was particularly exciting to discover a molecular pathway in these cells that appears to have been specifically targeted during evolution and may help explain their specialized role in generating the advanced human cortex,” Bhaduri said.

Tantalizingly, problems with mTOR signaling have also been linked to autism and other uniquely human neurodevelopmental disorders, suggesting new questions about whether pathways involved in the relatively recent evolution of our unusually large brains play some special role in these disorders.

For his part, Pollen says he has been working towards these experiments for more than a decade, since he was an undergraduate researcher studying the evolution of cichlid fishes in Tanzania’s Lake Tanganyika, just miles from Jane Goodall’s famous chimpanzee research station at Gombe Stream National Park.

“Being so close to wild chimpanzees made me want to ask questions about our own species’ evolution,” Pollen said. “But first we needed genomes, stem cells, and single-cell RNA sequencing to be able to understand the evolutionary programs that drive brain development in the two species. All of these things have since fallen into place, letting us address these long-standing questions more precisely than ever before.”

Source: University of California, San Francisco [February 08, 2019]



‘X-ray gun’ helps researchers pinpoint the origins of pottery found on...

About eight hundred years ago, a ship sank in the Java Sea off the coast of the islands of Java and Sumatra in Indonesia. There are no written records saying where the ship was going or where it came from–the only clues are the mostly-disintegrated structure of the vessel and its cargo, which was discovered on the seabed in the 1980s. Since the wreck’s recovery in the 1990s, researchers have been piecing together the world that the Java Sea Shipwreck was part of. In a new study in the Journal of Archaeological Science, archaeologists have demonstrated a new way to tell where the ceramic cargo of the ship originally came from: by zapping it with an X-ray gun.

'X-ray gun' helps researchers pinpoint the origins of pottery found on ancient shipwreck
Ceramic bowls in situ at the Java Sea Shipwreck site 
[Credit: Field Museum/Pacific Sea Resources]

“It’s amazing that we can pinpoint the production area of materials from an 800-year-old shipwreck,” says Wenpeng Xu, the study’s lead author, a graduate student at the University of Illinois at Chicago, which has a joint graduate program in Anthropology with the Field Museum. “It helps us learn the details of trade relationships–knowing how people interacted in the past is very important for us to understand the present.”
The Field Museum is home to an estimated 7,500 pieces of cargo recovered from the wreck, including the 60 ceramic pieces from the shipwreck analyzed in this study: bowls and boxes made of porcelain covered in a bluish-white glaze called qingbai. Based on the style of the ceramics, scientists knew that it came from southeastern China, but style alone isn’t enough to pinpoint a piece’s origin because many kilns produced similar-looking pieces. By comparing the chemical makeups of ceramics from the wreck and from different kiln sites in China, the researchers were able to more precisely determine where the ceramics were made.

'X-ray gun' helps researchers pinpoint the origins of pottery found on ancient shipwreck
Examining qingbai sherds at the Shimuling kiln site, Dehua
[Credit: Kai Li]

Ceramics from different sites have different chemical compositions because of variations in the elements present in that region’s clay or in the recipes that potters used to mix their clay. If a piece of pottery from the shipwreck matches the pottery found at an archaeological site, it’s a pretty safe bet that the pottery originated there. “Each kiln site uses its own materials and ingredients for clay–that’s what makes each sample’s fingerprint unique,” explains Xu. “If the fingerprint of the sample matches the fingerprint of the kiln site, then it’s highly possible that that’s where the sample came from.” This is where the X-ray gun comes in.
“We used a portable X-ray fluorescence detector–it looks a lot like a ray gun,” says Lisa Niziolek, Field Museum Boone Research Scientist and co-author of the study. The science behind the compositional analysis is complex, but Niziolek breaks it down: “You’re shooting X-rays into a material you’re interested in. It excites the material’s atoms. Energy goes flying out, and this measures that energy. Different elements have different signatures of energy that comes back out.”

'X-ray gun' helps researchers pinpoint the origins of pottery found on ancient shipwreck
Qingbai ceramics from the Field Museum’s Java Sea Shipwreck collection 
[Credit: Kate Golembiewski/Field Museum]

Knowing the precise origins of cargo on the ship reveals the size and complexity of trade networks at the time. The ceramics in the study were created over 2,000 miles from where the ship sank–about the distance between New York and Las Vegas.
“A key that’s emerging is that the shipwreck tells us that there were huge trade networks in the 12th and 13th centuries,” says Field Museum MacArthur Curator of Anthropology and study co-author Gary Feinman. “We’re taught to associate vast trade networks with Europeans like Magellan and Marco Polo, but Europeans weren’t a big part of this network that went from Asia to Africa. Globalization isn’t just a recent phenomenon–it’s not just Eurocentric, not just tied to modern capitalism. The ancient world was more interconnected than a lot of people thought.”

'X-ray gun' helps researchers pinpoint the origins of pottery found on ancient shipwreck
Ceramics from the Field Museum’s Java Sea Shipwreck collection being analyzed by portable X-ray fluorescence
[Credit: (c) Field Museum/Kate Golembiewski]

“People often refer to shipwrecks as time capsules, but the Java Sea Wreck is more than just that,” says Niziolek. “A time capsule represents a moment frozen in time, but that ignores the way these results reveal these vast and changing socioeconomic networks.”

Feinman agrees: “It’s almost the opposite of a nice, bounded time capsule, it’s more like a window that opens up to a wide horizon and tells us how this material came onto this ship before it sank.”

Source: Field Museum [February 08, 2019]



On the land, one-quarter of vertebrates die because of humans

Humans have a “disproportionate effect” on the other species of vertebrates that share Earth’s surface with us, causing more than 25 percent of the deaths among an array of species all over the globe, according to a recently published study.

On the land, one-quarter of vertebrates die because of humans
The single most prominent species in a study of mortality among terrestrial vertebrates
was white-tailed deer [Credit: ESF]

A team of scientists from the SUNY College of Environmental Science and Forestry (ESF) in Syracuse, New York, and the U.S. Department of Agriculture analyzed the deaths of 42,755 animals that were reported in 1,114 published studies. They found that 28 percent of the animals’ deaths were directly caused by humans.

“We all know humans can have a substantial effect on wildlife. That we are only one among over 35,000 species of terrestrial vertebrates worldwide yet responsible for more than one-fourth of their deaths provides perspective on how large our effect actually is,” said co-author Jerrold L. Belant, the Camp Fire Conservation Fund professor at ESF. “And that’s just direct causes. When you also consider urban growth and other land use changes that reduce habitat, it becomes clear humans have a disproportionate effect on other terrestrial vertebrates.”

Belant conducted the study with Jacob E. Hill, another ESF faculty member, and Travis L. DeVault of the USDA Animal and Plant Health Inspection Service.

The study included mammals, birds, reptiles and amphibians that died in North and South America, Europe, Asia, Africa and Oceania between 1970 and 2018. All of them had been collared or tagged as part of research projects.

The study authors analyzed deaths of known cause among 120,657 individual animals from 305 vertebrate species; some 42,000 had met a “known fate.” Overall, 28 percent of deaths were directly caused by humans; the other 72 percent died from natural sources. Predation (55 percent) and legal harvest (17 percent) were the leading sources of mortality.

Hill pointed out that humans’ impact was not equal across all the different species. “Larger animals were more likely to be killed by humans than smaller species. Adult animals were more likely than juveniles to be killed by humans,” he said.

The scientists concluded that humans are a major contributor to terrestrial vertebrate mortality, potentially impacting evolutionary processes and ecosystem functioning. The authors point out that 75 percent of Earth’s land surface is affected by human activity and that widespread extinctions of animal species are a defining trait of an era dubbed the Anthropocene.

“It’s a wake-up call,” Belant said. “Consider deforestation rates and the bleaching of coral reefs from increased sea temperatures. This is one more piece of evidence to add to the list, one more example of the effect we’re having on the planet.”

The study was published in January in the journal Global Ecology and Biogeography.

Author: Claire B. Dunn | Source: SUNY College of Environmental Science and Forestry [February 11, 2019]



Ptolemaic ship repair workshop uncovered in Sinai

Excavations carried out by an Egyptian mission at the Tel Abu Seify archaeological site in Northern Sinai uncovered the remains of a limestone building that was once a workshop for the construction and repair of boats and vessels during the Ptolemaic and Roman periods. The site is said to have been the location of the Roman fortress of Silla.

Ptolemaic ship repair workshop uncovered in Sinai
Credit: Egypt. Ministry of Antiquities

Mostafa Waziri, secretary general of the Supreme Council of Antiquities, said that the workshop includes two dry dockyards where ships were built or repaired.

Ptolemaic ship repair workshop uncovered in Sinai

Ptolemaic ship repair workshop uncovered in Sinai
Credit: Egypt. Ministry of Antiquities

But regretfully, along the span of time as the workshop lost its function, after the Nile branch passing across the area dried up, some blocks of the workshop were removed to be used in the construction of other buildings.

Ptolemaic ship repair workshop uncovered in Sinai

Ptolemaic ship repair workshop uncovered in Sinai
Credit: Egypt. Ministry of Antiquities

Remains of wooden beams, shipwrecks, bronze and iron nails of different sizes, fish bones and clay pots were found inside the workshop.

Author: Nevine El-Aref | Source: Ahram Online [February 13, 2019]



First Neanderthal footprints found in Gibraltar

The prestigious international journal Quaternary Science Reviews has just published a paper which has involved the participation of Gibraltarian scientists from The Gibraltar National Museum alongside colleagues from Spain, Portugal and Japan. The results which have been published come from an area of the Catalan Bay Sand Dune.

First Neanderthal footprints found in Gibraltar
The place where the footprint was found [Credit: Universdad de Sevilla]

This work started ten years ago, when the first dates using the OSL method were obtained. It is then that the first traces of footprints left by vertebrates were found. In subsequent years the successive natural collapse of sand has revealed further material and has permitted a detailed study including new dates.

The sand sheets in the rampant dunes above Catalan Bay are a relic of the last glaciation, when sea level was up to 120 metres below present levels and a great field of dunes extended eastwards from the base of the Rock. The identified footprints correspond to species which are known, from fossil material, to have inhabited Gibraltar.

The identified footprints correspond to Red Deer, Ibex, Aurochs, Leopard and Straight-tusked Elephant. In addition the scientists have found the footprint of a young human (106-126 cm in height), possibly Neanderthal, which dates to around 29 thousand years ago. It would coincide with late Neanderthal dates from Gorham’s Cave.

If confirmed to be Neanderthal, these dunes would become only the second site in the world with footprints attributed to these humans, the other being Vartop Cave in Romania. These findings add further international importance to the Gibraltar Pleistocene heritage, declared of World Heritage Value in 2016.

The research was supported by HM Government of Gibraltar under the Gibraltar Caves Project and the annual excavations in the Gibraltar Caves, with additional support to the external scientists from the Spanish EU project MICINN-FEDER: CGL2010-15810/BTE.

Minister for Heritage John Cortes MP commented, “This is extraordinary research and gives us an incredible insight into the wildlife community of Gibraltar’s past. We should all take a moment to imagine the scene when these animals walked across our landscape. It helps us understand the importance of looking after our heritage. I congratulate the research team on uncovering this fascinating, hidden evidence of our Rock’s past.”

Source: University of Seville [February 13, 2019]



2019 February 13 The Helix Nebula in Hydrogen and Oxygen Image…

2019 February 13

The Helix Nebula in Hydrogen and Oxygen
Image Credit & Copyright: Andrew Campbell

Explanation: Is the Helix Nebula looking at you? No, not in any biological sense, but it does look quite like an eye. The Helix Nebula is so named because it also appears that you are looking down the axis of a helix. In actuality, it is now understood to have a surprisingly complex geometry, including radial filaments and extended outer loops. The Helix Nebula (aka NGC 7293) is one of brightest and closest examples of a planetary nebula, a gas cloud created at the end of the life of a Sun-like star. The remnant central stellar core, destined to become a white dwarf star, glows in light so energetic it causes the previously expelled gas to fluoresce. The featured picture, taken in the light emitted by oxygen (shown in blue) and hydrogen (shown in red), was created from 74 hours of exposure over three months from a small telescope in a backyard of suburban Melbourne, Australia. A close-up of the inner edge of the Helix Nebula shows complex gas knots of unknown origin.

∞ Source: apod.nasa.gov/apod/ap190213.html

T. rex had an unusually flexible skull

Senckenberg scientist Ingmar Werneburg, together with an international team, re-examined the skull structure of Tyrannosaurus rex. Using an “anatomical network analysis,” the researchers showed that the carnivorous dinosaur had an extremely flexible skull structure. Different bone modules led to a highly flexible muzzle that aided in tearing apart prey animals.

T. rex had an unusually flexible skull
T. rex had an unusually flexible skull [Credit: Senckenberg]

Tyrannosaurus rex – the “King of the Tyrant Lizards” – owes its name in part to its impressive teeth and skull. The latter was subject to closer scrutiny by an international team of scientists from Germany, Switzerland, Great Britain, Spain, and the USA.
“We compared the skull of T. rex with the skull construction of modern terrestrial vertebrates and used an anatomical network analysis to examine which skull bones are connected to each other,” explains the study’s lead author, PD Dr. Ingmar Werneburg of the Senckenberg Centre for Human Evolution and Palaeoenvironment at the University of Tübingen.

The analysis revealed that, among all groups of animals analyzed in the study, the large carnivore possessed the highest number of “skull modules” – skull bones that form units with adjacent bones. This resulted in a particularly high mobility of the skull.

T. rex had an unusually flexible skull
The skull of T. rex was compared to the skulls of an opossum, a chicken, and a turtle, among others.
The colours indicate different skull modules [Credit: Werneburg]

“We were most surprised to discover the presence of separate upper and lower muzzle modules, which probably could move independent of each other,” adds the scientist from Tübingen.
The researchers hypothesize that the feeding habits of Tyrannosaurus rex may have led to the complexity of its skull. The division into a lower and an upper muzzle module may have provided a certain amount of flexibility to the tooth-bearing part of the muzzle that aided in the forceful tearing of prey animals.

“This trait, combined with teeth anchored within tooth pockets and two large temporal fenestrae (openings) as attachment points for the strong jaw muscles, made T. rex the ‘ideal carnivore,’ adds Werneburg in summary.

The study was published today in the journal Scientific Reports.

Source: Senckenberg Research Institute and Natural History Museum [February 07, 2019]



NASA’s Van Allen Probes Begin Final Phase of Exploration in Earth’s Radiation...

NASA – Van Allen Probes Mission patch.

Feb. 12, 2019

Two tough, resilient, NASA spacecraft have been orbiting Earth for the past six and a half years, flying repeatedly through a hazardous zone of charged particles around our planet called the Van Allen radiation belts. The twin Van Allen Probes, launched in August 2012, have confirmed scientific theories and revealed new structures and processes at work in these dynamic regions. Now, they’re starting a new and final phase in their exploration.

On Feb. 12, 2019, one of the twin Van Allen Probes begins a series of orbit descent maneuvers to bring its lowest point of orbit, called perigee, just under 190 miles closer to Earth. This will bring the perigee from about 375 miles to about 190 miles — a change that will position the spacecraft for an eventual re-entry into Earth’s atmosphere about 15 years down the line.

“In order for the Van Allen Probes to have a controlled re-entry within a reasonable amount of time, we need to lower the perigee,” said Nelli Mosavi, project manager for the Van Allen Probes at the Johns Hopkins Applied Physics Laboratory, or APL, in Laurel, Maryland.  “At the new altitude, aerodynamic drag will bring down the satellites and eventually burn them up in the upper atmosphere. Our mission is to obtain great science data, and also to ensure that we prevent more space debris so the next generations have the opportunity to explore the space as well.”

The other of the two Van Allen Probes will follow suit in March, also commanded by the mission operations team at APL, which designed and built the satellites.

Animation above: The twin Van Allen Probes have spent more than six years orbiting through Earth’s radiation belts. Orbit changes in early 2019 will ensure that the spacecraft eventually de-orbit and disintegrate in Earth’s atmosphere. Animation Credits: NASA Goddard’s Scientific Visualization Studio.

The Van Allen Probes spend most of their orbit within Earth’s radiation belts: doughnut-shaped bands of energized particles — protons and electrons — trapped in Earth’s magnetic field. These fast-moving particles create radiation that can interfere with satellite electronics and could even pose a threat to astronauts who pass through them on interplanetary journeys. The shape, size and intensity of the radiation belts changes in response to solar activity, which makes predicting their state difficult.

Originally designated as a two-year mission — based on predictions that no spacecraft could operate much longer than that in the harsh radiation belts — these rugged spacecraft have operated without incident since 2012, and continue to enable groundbreaking discoveries about the Van Allen Belts.

Five Things about Radiation Donuts

Video above: Credits: NASA’s Goddard Space Flight Center.

“The Van Allen Probes mission has done a tremendous job in characterizing the radiation belts and providing us with the comprehensive information needed to deduce what is going on in them,” said David Sibeck, mission scientist for the Van Allen Probes at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The very survival of these spacecraft and all their instruments, virtually unscathed, after all these years is an accomplishment and a lesson learned on how to design spacecraft.”

Each spacecraft will be moved to a new, lower perigee of about 190 miles above Earth through a series of five two-hour engine burns. Because the Van Allen Probes spin while in orbit, the dates of these burns had to be chosen carefully. The needed geometry happens just once or twice per year: for spacecraft B, that period falls Feb. 12-22 of this year, and for spacecraft A, it’s March 11-22.

The engine burns will each use about 4.4 pounds of propellant, leaving the spacecraft with enough fuel to keep their solar panels pointed at the Sun for about one more year.

“We’ll continue to operate and obtain new science in our new orbit until we are out of fuel, at which point we won’t be able to point our solar panels at the Sun to power the spacecraft systems,” said Mosavi.

Image above: After performing de-orbit maneuvers in February and March 2019, the Van Allen Probes’ highly elliptical orbits will gradually tighten over the next 15-25 years as the spacecraft experience atmospheric drag at perigee, the point in their orbits closest to Earth. This atmospheric drag will pull them into a circular orbit as early as 2034, at which point the spacecraft will begin to enter Earth’s atmosphere and safely disintegrate. Image Credits: Johns Hopkins APL.

During their last year or so of life, the Van Allen Probes will continue to gather data on Earth’s dynamic radiation belts. And their new, lower passes through Earth’s atmosphere will also provide new insight into how oxygen in Earth’s upper atmosphere can degrade satellite instruments — information that could help engineers design more resilient satellite instruments in the future.

“The spacecraft and instruments have given us incredible insight into spacecraft operations in a high-radiation environment,” said Mosavi. “Everyone on the mission feels a real sense of pride and accomplishment in the work we’ve done and the science we’ve provided to the world — even as we begin the de-orbiting maneuvers.”

Read more about what the Van Allen Probes have accomplished since 2012: http://vanallenprobes.jhuapl.edu/News-Center/newsArticles/article.php?id=20190210

For more on the Van Allen Probes: http://www.nasa.gov/vanallenprobes

Image (mentioned), Animation (mentioned), Video (mentioned), Text, Credits: NASA/Rob Garner/GSFC/Karen C. Fox/Johns Hopkins University Applied Physics Lab/Geoff Brown.

Greetings, Orbiter.chArchive link

In Solar System’s Symphony, Earth’s Magnetic Field Drops the Beat

NASA – THEMIS Mission patch.

Feb. 12, 2019

Space isn’t silent. In fact, an entire orchestra of instruments fills our near-Earth environment with eerie sounds. Scientists have long known about space phenomena involving electromagnetic waves travelling around Earth that resonate like string instruments and whistle like wind instruments. Now, new research published in Nature Communications has added a percussive member to the cosmic ensemble: a giant drum, triggered by plasma jets striking the boundary of the protective magnetic bubble surrounding our planet.

This magnetic bubble, known as the magnetosphere, is encased by a boundary region known as the magnetopause, our first barrier to high-energy particles coming from the Sun. At the magnetopause, the majority of solar particles are deflected around Earth, but under certain conditions some sneak through. Understanding the ­­­­­­­mechanics of the magnetopause is key to helping keep our satellites, telecommunications and astronauts safe from the potentially harmful radiation these particles bring.

Earth’s Magnetic Field Vibrates Like a Drum

Video above: NASA’s THEMIS mission proves a 45-year old theory that the outer boundary of Earth’s magnetic field vibrates like a drum. Video Credits: Video courtesy Martin Archer, Queen Mary University of London.

Using data from NASA’s Time History of Events and Macroscale Interactions during Substorms, or THEMIS, mission, the scientists discovered ­that when the magnetopause is struck by a jet of plasma from the Sun, it vibrates like a drum, with waves echoing back and forth along its surface, much like they do on top of a drumhead. The new discovery comes several decades after such behavior was first theorized.

“Given the lack of evidence over the 45 years since they were proposed, there had been speculation that these drum-like vibrations might not occur at all,” said Martin Archer, space physicist at Queen Mary University of London and lead author of the new paper. “Now we see that waves on the magnetopause’s surface reflect between two points near the magnetic poles — acting very much like a drum.”

Image above: Illustration of a plasma jet impact (yellow) generating standing waves at the boundary (blue) of Earth’s magnetic shield (green). Image Credits: E. Masongsong/UCLA, M. Archer/QMUL, H. Hietala/UTU.

Inside the magnetosphere, scientists have long been listening in on space sounds created by various electromagnetic waves. This veritable orchestra of waves can be heard as sound when processed correctly, and they even exhibit similar behaviors to certain musical instruments. So-called magnetosonic waves pulse through plasma in the same way sound bounces through wind instruments. Another type of wave, known as an Alfvén wave, resonates along magnetic field lines, just like string instruments’ vibrating strings. While both of these types of waves can travel anywhere in space, the newly discovered waves are a type of surface waves — waves that require some sort of boundary to travel along.

In this case the magnetopause acted as the boundary. When a plasma jet — the drumstick — strikes the magnetopause, surface waves form a standing wave pattern — where the ends appear to be standing still while other points vibrate back and forth — just like a drumhead. The fixed points in the wave, which are the rim or edge of the drum, are near Earth’s magnetic poles; the waves vibrate the surface of the magnetopause in between. While the wave itself remains on the surface, the vibrations ultimately work their way down into the magnetosphere and trigger other types of waves.

“The waves likely penetrate far into the inner magnetosphere causing ultra-low frequency waves, which affect things like radiation belts, the aurora, and even the ionosphere,” Archer said.

The Sounds of Earth’s Magnetic Drum in Space

Video above: The signals recorded by the THEMIS probes converted to audible sound. Video Credits: Video courtesy Martin Archer, Queen Mary University of London.

The new study used data from the THEMIS mission, which initially used five identical probes to determine what physical process in near-Earth space initiates the auroras.

“The authors make great use of observations from a time early in the mission when the spacecraft followed each other along their mutual orbit like pearls on a string,” said David Sibeck, THEMIS project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “In this fortunate case, the THEMIS spacecraft were in just the right place to see the drumstick and hear the drum.”

Image above: Different types of plasma waves triggered by various mechanisms, occupy different regions of space around Earth. Image Credits: NASA’s Goddard Space Flight Center/Mary Pat Hrybyk-Keith.

The scientists plan to look through archival THEMIS data for more of these events around Earth and determine how often the magnetopause may be booming like a drum. This research may also help provide insights into how to look for this phenomenon at other planets with magnetospheres, like Jupiter and Saturn, and what effect they may have in those systems.

Related Links

Nature Communications: https://doi.org/10.1038/s41467-018-08134-5

Learn more about NASA’s THEMIS and ARTEMIS Missions: https://www.nasa.gov/artemis

NASA Listens in as Electrons Whistle While They Work: https://www.nasa.gov/feature/goddard/2017/nasa-listens-in-as-electrons-whistle-while-they-work

Eavesdropping in Space: How NASA records eerie sounds around Earth: https://blogs.nasa.gov/sunspot/2018/12/11/eavesdropping-in-space-how-nasa-records-eerie-sounds-around-earth/

THEMIS (Time History of Events and Macroscale Interactions During Substorms): http://www.nasa.gov/mission_pages/themis/main/index.html

Space Weather:  https://www.nasa.gov/subject/3165/space-weather

Images (mentioned), Videos (mentioned), Text, Credits: NASA/Rob Garner/GSRC/Mara Johnson-Groh.

Greetings, Orbiter.chArchive link

Aquamarine With Schorl On Pericline | #Geology #GeologyPage…

Aquamarine With Schorl On Pericline | #Geology #GeologyPage #Mineral

Locality: Davib East Farm, Karibib District, Erongo Region, Namibia

Size: 4.9 × 5.6 × 3.1 cm

Largest Crystal: 5.60cm

Photo Copyright © Wittig Minerals / e-rocks. com

Geology Page



Exercise Research and Biology Hardware Checks Aboard Orbital Lab

ISS – Expedition 58 Mission patch.

February 12, 2019

The Expedition 58 crew explored space exercise and checked out biology hardware today aboard the International Space Station. The space residents supplemented their research activities and kept the orbital lab systems in tip-top shape.

Daily exercise in space is important so astronauts can fight muscle and bone loss caused by living in weightlessness. Doctors are seeking to optimize workouts for crews to stay in shape for strenuous activities like spacewalks, returning to Earth and adjusting to gravity.

Image above: NASA astronaut Anne McClain is surrounded by exercise gear, including laptop computers and sensors that measure physical exertion and aerobic capacity, during a workout session. Image Credit: NASA.

Anne McClain of NASA contributed to that research today strapping into an exercise bike while attached to breathing tubes and sensors. Scientists measured her breathing and aerobic capacity to understand the effects of microgravity on pulmonary function and physical exertion.

International Space Station (ISS). Image Credit: NASA

Canadian Space Agency astronaut David Saint-Jacques worked on a pair of incubators throughout Tuesday. He disconnected hardware in the Kubik incubator that houses small biology studies in the Columbus lab module. Afterward, he glided into the Kibo lab module and set up a carbon dioxide meter inside the Space Automated Bioproduct Laboratory supporting a wide variety of life sciences.

The commander, Oleg Kononenko of Roscosmos, worked primarily in the station’s Russian segment on Tuesday beginning the day working on life support gear. The highly experienced cosmonaut then moved onto space navigation research before charging the emergency phone inside the Soyuz MS-11 spacecraft.

Related links:

Expedition 58: https://www.nasa.gov/mission_pages/station/expeditions/expedition58/index.html

Exercise bike: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=821

Breathing: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=103

Aerobic capacity: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=644

Kubik: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=894

Columbus lab module: https://www.nasa.gov/mission_pages/station/structure/elements/europe-columbus-laboratory

Kibo lab module: https://www.nasa.gov/mission_pages/station/structure/elements/japan-kibo-laboratory

Automated Bioproduct Laboratory: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=1148

Space navigation research: https://www.energia.ru/en/iss/researches/develop/03.html

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Images (mentioned), Text, Credits: NASA/Mark Garcia.

Best regards, Orbiter.chArchive link

Swimming Strokes Bacteria swim around inside our guts using…

Swimming Strokes

Bacteria swim around inside our guts using tiny propellers, called flagella, fuelled by chemicals sluicing nearby. Here Escherichia coli (E.coli) bacteria are using a different energy source – proteorhodopsin – which releases energy when exposed to light. Under an illuminated pattern, the bacteria swim quickly in lit areas, and slowly in unlit ones, producing – with a little guidance from clever physics – a portrait of Albert Einstein matching a projected image. Switching the pattern signals the bacteria to paint a different picture – guided by changes in the light and dark areas. Einstein’s face morphs into Charles Darwin, a living portrait created in around five minutes. Aside from giving the tiny swimmers a new hobby, scientists hope to use the artistic technique elsewhere – perhaps guiding clouds of bacteria to push drug-carrying devices around the body. It’s likely both Einstein and Darwin would approve.

Today is the 210th Anniversary of Charles Darwin’s birth

Written by John Ankers

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Ancient carved stones from Nabatean temple returned to Jordan

Three finely carved stones from an ancient temple in modern-day Jordan have been returned to the country thanks to the expertise of an Oxford University archaeologist.

Ancient carved stones from Nabatean temple returned to Jordan
Frieze fragment from Period III Altar platform at Khirbet et-Tannur
[Credit: Juan Orlandis Habsburgo]

The pieces formed part of Khirbet et-Tannur, a temple complex 70km north of Petra, the rose-red rock-cut city of the Nabataeans. The temple flourished as a place of sanctuary from the second century BC until the middle of the fourth century AD.

Featuring grape vine and vegetal motifs, the artefacts were saved from private sale after an art dealer in Spain contacted Oxford expert Dr Judith McKenzie, of the Faculty of Classics, who was able to identify the items as pieces of the Khirbet et-Tannur altar platform.

Dr McKenzie, who has led international studies of the archaeological finds from Khirbet et-Tannur, resulting in two books, said: ‘Khirbet et-Tannur was first excavated in 1937, and the artefacts found at the site were split between Cincinnati Art Museum in the United States and the archaeological museum in Jordan.

‘The temple is famous in Jordan because the Vegetation Goddess panel from it is prominently displayed in the entrance of the Jordan Museum in Amman.One of the returned pieces joins the Fish Goddess bust from the altar platform in the museum. It is thus important that the pieces be displayed in the Jordan Museum, along with the other pieces from Khirbet et-Tannur.’

Of the sequence of events that led to the artefacts’ return, Dr McKenzie said: ‘Mr Diego Lopez de Aragon of Galeria Lopez de Aragon, a third-generation art dealer with an important presence in the international art market and who intended to sell these three particular items, contacted me in the summer of 2018 to ask for my opinion to clarify their provenance. I immediately recognised them as pieces of the altar platform at Khirbet et-Tannur, and I was able to demonstrate that they should be returned to Jordan.

‘Securing their return was a collaborative effort involving myself, the art dealer, and various authorities in Spain and Jordan, including the Department of Antiquities of the Hashemite Kingdom of Jordan, Her Royal Highness Princess Dana Firas, President of the Petra National Trust and UNESCO Goodwill Ambassador for Cultural Heritage, the Spanish Ministry of Culture (Heritage Department), and the Jordanian Embassy in Madrid.’

Ancient carved stones from Nabatean temple returned to Jordan
Frieze fragment from Period III Altar platform at Khirbet et-Tannur
[Credit: Juan Orlandis Habsburgo]

Diego Lopez de Aragon of Galeria Lopez de Aragon, which exhibits each year at TEFAF Maastricht, said: ‘These Nabataean pieces formed part of the collection belonging to a Spanish diplomat and collector, Juan Duran-Loriga y Rodriganez [1926–2016]. He was posted to Jerusalem as vice-consul general for Spain in the 1950s, and years later, in 1969, he was appointed Spanish ambassador to Amman. The pieces became part of his collection once he was back in Spain.

‘Galeria Lopez de Aragon and Galeria Escorial Casado acquired the three pieces from the Ambassador’s nephew and heir in 2017. The heir later provided us with a copy of Nelson Glueck’s excavation book, Deities and Dolphins, that he found in his uncle’s library. Consequently, we realised that the stones belonged to the Khirbet et-Tannur Temple in Jordan.

‘Therefore, we decided to contact Dr McKenzie to help us catalogue the stones. Thanks to her knowledge and information on Glueck’s excavation, we proceeded to donate the stones to the Hashemite Kingdom of Jordan. We truly believe that such singular pieces should be exhibited at the Jordan Museum in Amman, hence our decision to donate them.’

Her Royal Highness Princess Dana Firas said: ‘We are grateful to Dr Judith McKenzie and Diego Lopez de Aragon for their collaboration and their critical role in repatriating these important pieces to Jordan. This outcome stands as a successful example of cooperation among governments, the private sector, and civil society to honor the country-origin of archaeological pieces. We are proud to have these important Nabataean pieces back in Jordan, where they belong, and we look forward to displaying them with other pieces from Khirbet et-Tannur that tell the story of our history and rich cultural heritage.’

Dr McKenzie, Director of the Manar al-Athar Open-Access Photo Archive in Oxford’s Faculty of Classics, added: ‘These pieces are unique in the Jordanian context and an important part of the region’s cultural heritage. It’s very satisfying to know they have been returned rather than being sold on the private market, and I’m thankful to the dealer for proactively seeking out the view of an expert. Their successful return also shows the important role played by Jordan’s own civil society organisations, such as the Petra National Trust.’

Source: University of Oxford [February 06, 2019]




https://t.co/hvL60wwELQ — XissUFOtoday Space (@xufospace) August 3, 2021 Жаждущий ежик наслаждается пресной водой после нескольких дней в о...