среда, 10 июля 2019 г.

2019 July 10 4000 Exoplanets Video Credit: SYSTEM Sounds (M….

2019 July 10

4000 Exoplanets
Video Credit: SYSTEM Sounds (M. Russo, A. Santaguida); Data: NASA Exoplanet Archive

Explanation: Over 4000 planets are now known to exist outside our Solar System. Known as exoplanets, this milestone was passed last month, as recorded by NASA’s Exoplanet Archive. The featured video highlights these exoplanets in sound and light, starting chronologically from the first confirmed detection in 1992. The entire night sky is first shown compressed with the central band of our Milky Way Galaxy making a giant U. Exoplanets detected by slight jiggles in their parents-star’s colors (radial velocity) appear in pink, while those detected by slight dips in their parent star’s brightness (transit) are shown in purple. Further, those exoplanets imaged directly appear in orange, while those detected by gravitationally magnifying the light of a background star (microlensing) are shown in green. The faster a planet orbits its parent star, the higher the accompanying tone played. The retired Kepler satellite has discovered about half of these first 4000 exoplanets in just one region of the sky, while the new TESS mission is on track to find even more, all over the sky, orbiting the brightest nearby stars. Finding exoplanets not only helps humanity to better understand the potential prevalence of life elsewhere in the universe, but also how our Earth and Solar System were formed.

∞ Source: apod.nasa.gov/apod/ap190710.html

Star formation may be halted by cold ionised hydrogen

A composite image showing our Galaxy, the Milky Way, rising above the Engineering Development Array at the Murchison Radio-astronomy Observatory in Western Australia. The location of the centre of our Galaxy is highlighted alongside the ionized hydrogen (H+) signal detected from this region of sky. The white-blueish light shows the stars making up the Milky Way and the dark patches obscuring this light shows the cold gas that is interspersed between them. Credit: Engineering Development Array image courtesy of ICRAR. Milky Way image courtesy of Sandino Pusta.

For the first time ionised hydrogen has been detected at the lowest frequency ever towards the centre of our Galaxy. The findings originate from a cloud that is both very cold (around -230 degrees Celsius) and also ionised, something that has never been detected before. This discovery may help to explain why stars don’t form as quickly as they theoretically could.

Dr. Raymond Oonk (ASTRON/Leiden Observatory/SURFsara) led this study which is published today in MNRAS. He said: «The possible existence of cold ionised gas had been hinted at in previous work, but this is the first time we clearly see it.»

Ionisation is an energetic process that strips electrons away from atoms. The atom will become electrically charged and can then be called an ion. This typically happens in gas that is very hot (10000 degrees Celsius) and where atoms can easily lose their electrons. It was therefore puzzling to discover the ionised hydrogen from very cold gas in this cloud. Normal energy sources, such as photons from massive stars, would not cause this. More exotic energy forms, such as high energy particles created in supernova shockwaves and near black holes, are more likely to be responsible.

Dr. Oonk continues: «This discovery shows that the energy needed to ionise hydrogen atoms can penetrate deep into cold clouds. Such cold clouds are believed to be the fuel from which new stars are born. However, in our Galaxy we know that the stellar birth rate is very low, much lower than naively expected. Perhaps the energy observed here acts as a stabiliser for cold clouds, thereby preventing them from collapsing on to themselves and forming new stars.»

The observation was made with the Engineering Development Array (EDA), a prototype station of the Square Kilometre Array (SKA), the worlds’ largest radio telescope. A/Prof. Randall Wayth (Curtin University/ICRAR) says: «This detection was made possible by the wide bandwidth of the EDA and the extremely radio quiet location of the Murchison Radio-astronomy Observatory. The low frequency portion of the Square Kilometre Array will be built at this location in the coming years, so this excellent result gives us a glimpse of what the SKA will be capable of once it’s built.»

The data reduction was led by Emma Alexander (University of Manchester) as part of her summer student internship at ASTRON: «It’s a very exciting time to be coming into radio astronomy, and it was great to work on the first high resolution spectroscopic data from this SKA prototype station. The technologies that are being developed for the SKA, and the science results that come from them, will be a driving force for my generation of radio astronomers.»

This work was carried out as a collaboration between the Netherlands Institute for Radio Astronomy (ASTRON), Leiden University, the International Centre for Radio Astronomy Research (ICRAR), University of Manchester and the Square Kilometre Array.

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Asteroid Vesta originates from a cosmic ‘hit-and-run’ collision

The asteroid belt between Mars and Jupiter preserves the processes of planetary formation, frozen in time. Vesta, the second largest asteroid in this belt, provides an outstanding opportunity for scientists to investigate the origin and formation of planets. In particular, Vesta has kept its crust, mantle and metallic core, much like Earth. Careful mapping of Vesta by NASA’s Dawn mission showed that the crust at the south pole of Vesta is unusually thick.

Asteroid Vesta originates from a cosmic 'hit-and-run' collision
Asteroid Vesta [Credit: NASA/JPL-Caltech/UCAL/MPS/DLR/IDA]

In a paper just published in Nature Geoscience, Dr. Yi-Jen Lai of the Macquarie University Planetary Research Centre and Macquarie GeoAnalytical and her colleagues propose a new evolutionary history of Vesta involving a giant impact. This is based on precise age determinations of zircon crystals from mesosiderites, a type of enigmatic Vestan meteorite, and resolves past uncertainties about the evolution of Vesta.

Mesosiderites are a type of stony iron meteorite, consisting of crust and molten core materials from an asteroid/asteroids. These mysterious, rare meteorites give unique insights into the catastrophic break-up of differentiated (layered) asteroids, most likely Vesta.

Lead author, Dr. Makiko Haba of Tokyo Institute of Technology says, «The major challenge is that fewer than 10 zircon grains favourable for age dating had been reported over a few decades. We developed a new method for finding zircons in mesosiderites and eventually prepared enough grains for this study.»

The team carried out high-precision dating using the uranium and lead isotopes of two dozen zircons in mesosiderites at the world’s leading geoscience research university, the ETH Zurich in Switzerland.

Macquarie’s Dr. Yi-Jen Lai says, «We discovered two significant dates: 4,558.5 and 4,525.39 million years ago, that relate to the initial crust formation and metal-silicate mixing caused by a cosmic hit-and-run collision.»

The researchers propose the new hit-and-run explanation for these two important new time points. In the new model, after Vesta had already differentiated into distinct crust, mantle and core layers, another asteroid about one-tenth Vesta’s size smashed into it, causing the large-scale disruption of the northern hemisphere.

The debris from this impact, made up from all three of Vesta’s layers, got stuck onto the southern hemisphere of Vesta, explaining the unusually thick crust that NASA’s Dawn spacecraft detected at Vesta’s south pole. The new model also successfully explains Vesta’s distinctive shape and the lack of the mantle mineral olivine in the Vestan meteorites.

The team believes the concept can be applied to other planetary bodies to reconstruct their histories.

Source: Macquarie University [July 04, 2019]



NASA Maps Surface Changes From California Quakes

ARIA — Advanced Rapid Imaging and Analysis logo.

July 9, 2019

Image above: NASA’s Advanced Rapid Imaging and Analysis (ARIA) team created this co-seismic Interferometric Synthetic Aperture Radar (InSAR) map, which shows surface displacement caused by the recent major earthquakes in Southern California, including the magnitude 6.4 and the magnitude 7.1 events on July 4 and July 5, 2019, respectively. Image Credits: NASA/JPL-Caltech.

Damage from two strong earthquakes that rattled Southern California on July 4 and July 5 — a magnitude 6.4 and a magnitude 7.1, respectively — can be seen from space. The epicenter of the quakes was near the city of Ridgecrest, about 150 miles (241 kilometers) northeast of Los Angeles. According to the U.S. Geological Survey, the 7.1 quake was one of the largest to hit the region in some 40 years.

The Advanced Rapid Imaging and Analysis (ARIA) team at NASA’s Jet Propulsion Laboratory in Pasadena, California, used synthetic aperture radar (SAR) data from the ALOS-2 satellite to produce a map showing surface displacement from the earthquakes. The post-quake imagery was acquired on July 8, 2019, and compared with April 8, 2018, data from the same region.

Each color cycle represents 4.8 inches (12 centimeters) of ground displacement either toward or away from the satellite. The linear features that cut the color fringes in the southeast indicate likely locations of surface rupture caused by the earthquakes, and the «noisy» areas in the northwest may indicate locations where the ground surface was disturbed by them.

The USGS reported over 1,000 aftershocks in the region following the July 5 earthquake. State and federal scientists, including those from the California Geological Survey and USGS, are using this surface deformation map in the field for assessing the damages and mapping the faults that broke during the two major earthquakes as well as the thousands of aftershocks.

In the aftermath of the earthquakes, NASA’s Earth Science Disasters Program is in communication with the California Earthquake Clearinghouse, which is coordinating response efforts with the California Air National Guard, the USGS and the Federal Emergency Management Agency. NASA analysts are using data from satellites to produce visualizations of land deformation and potential landslides, among other earthquake impacts, and are making them available to response agencies. NASA’s Disasters Program promotes the use of satellite observations in predicting, preparing for, responding to and recovering from disasters around the world.

The Japanese Aerospace Exploration Agency (JAXA) provided the ALOS-2 data for the production of the map. The ARIA team’s analysis was funded by NASA’s Disasters Program.

For more information about ARIA, visit: http://aria.jpl.nasa.gov

For more information about NASA’s Disasters Program, visit: http://disasters.nasa.gov

ALOS-2: https://directory.eoportal.org/web/eoportal/satellite-missions/a/alos-2

Japanese Aerospace Exploration Agency (JAXA): http://global.jaxa.jp/

Jet Propulsion Laboratory (JPL): https://www.nasa.gov/centers/jpl/home/index.html

Image (mentioned), Text, Credits: NASA/Tony Greicius/JPL/Esprit Smith.

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Not-Unsolved Mysteries: The “Lost” Apollo 11 Tapes

NASA — Apollo 11 patch.

July 9, 2019

With the 50th anniversary of the Apollo 11 moon landing approaching, reports have resurfaced that NASA lost some precious video footage of that first moonwalk.

Image above: Buz Aldrin assembles seismic experiment. Image Credits: NASA/Apollo 11.

Before diving into the details of two distinct events that seem to have become conflated, it’s worth emphasizing three key points:

— NASA searched for but could not locate some of the original Apollo 11 data tapes – “original” in the sense that they directly recorded data transmitted from the Moon. An intensive search of archives and records concluded that the most likely scenario was that the program managers determined there was no longer a need to keep the tapes — since all the video was recorded elsewhere — and they were erased and reused.

— The data on those tapes, including video data, was relayed to the Manned Spacecraft Center (now the Johnson Space Center), during the mission. The video was recorded there and in other locations; there is no missing video footage from the Apollo 11 moonwalk.

— The search discovered high-quality broadcast versions of the footage. NASA worked with Lowry Digital, a premier film restoration company, to process the video using techniques unavailable in 1969. The restored video was released in HD as part of the 40th anniversary of Apollo 11.

Further explanation means diving into the details of how Apollo sent data back to Earth and how NASA collected it.

Data from the Apollo 11 mission was sent from the spacecraft to three ground stations, one in California and two in Australia, which retransmitted it to the Manned Space Flight Center in Houston. The ground stations also recorded the data on special 1-inch, 14-track tapes, one track of which was for video. The video footage was recorded in «slow scan» — 10 video frames per second — which meant it couldn’t be directly broadcast over commercial television. The video was converted for broadcast and uplinked to a satellite, then downlinked to Houston, from which it was sent out to the world.

In early 2005, responding to inquiries from NASA retirees and others, NASA began a search for the 14-track data tapes. Ultimately, the agency couldn’t find the tapes and determined that they had most likely been erased and used again, which was standard practice at the time. The search, led by NASA engineer Dick Nafzger, focused on finding the specific tapes, knowing the data had all been recorded and saved elsewhere.

«There was no video that came down slow scan that was not converted live, fed live, to Houston and fed live to the world,» Nafzger said at press conference showing some of the restored footage in 2009. «So, just in case anyone thinks there is video out there that hasn’t been seen, that is not the case.»

NASA News Briefing on Restored Apollo 11 Moonwalk Video — Clip 1

Video above: July 16, 2009 press conference on the search for and restoration of the Apollo 11 video. Video Credit: NASA.

During the search, though, Nafzger’s team came across video that had been converted to broadcast which was much higher quality than what they had been seeing.

“The team of people that I worked with, including myself obviously, was desperate to do something for history, if we could,» said Nafzger. «We came across broadcast-converted tapes during this search that were much better than we had seen. . . . We had tapes recorded in Sydney, Australia, during the mission. (We) found kinescopes at the National Archives that had not been viewed in 36 years that were made in Houston. We went to CBS archives and we found tapes that had been fed directly from Houston to CBS . .. . the raw data as recorded and archived.”

NASA News Briefing on Restored Apollo 11 Moonwalk Video — Clip 2

Video above: Working with a California company, NASA restored portions of the video and enhanced it for viewing in high definition and released the HD Apollo 11 videos in July 2009. Video Credit: NASA.

In 2019, a one-time NASA intern is selling what he describes as videotapes of the Apollo 11 moonwalk that he bought at an auction of surplus government goods. If the tapes are as described in the sale material, they are 2-inch videotapes recorded in Houston from the video that had been converted to a format that could be broadcast over commercial television and contain no material that hasn’t been preserved at NASA.

Related links:

NASA began a search for the 14-track data tapes: https://www.nasa.gov/mission_pages/apollo/apollo_tapes.html

Press conference showing some of the restored footage in 2009: http://www.youtube.com/watch?v=McyghW9rSIU

HD Apollo 11 videos: https://www.nasa.gov/multimedia/hd/apollo11_hdpage.html

Apollo 11: https://www.nasa.gov/mission_pages/apollo/apollo-11.html

Image (mentioned), Videos (mentioned), Text, Credits: NASA/Brian Dunbar.

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NASA Satellites Find Biggest Seaweed Bloom in the World

NASA — EOS Terra Mission patch / NASA — EOS Aqua Mission patch.

July 9, 2019

An unprecedented belt of brown algae stretches from West Africa to the Gulf of Mexico—and it’s likely here to stay. Scientists at the University of South Florida in St. Petersburg’s College of Marine Science used NASA satellite observations to discover and document the largest bloom of macroalgae in the world, dubbed the Great Atlantic Sargassum Belt, as reported in Science.

Based on computer simulations, they confirmed that this belt of the brown macroalgae Sargassum forms its shape in response to ocean currents. It can grow so large that it blankets the surface of the tropical Atlantic Ocean from the west coast of Africa to the Gulf of Mexico. In 2018, more than 20 million tons of it – heavier than 200 fully loaded aircraft carriers – floated in surface waters and became a problem to shorelines lining the tropical Atlantic, Caribbean Sea, Gulf of Mexico, and east coast of Florida, as it carpeted popular beach destinations and crowded coastal waters.

Image above: Too much Sargassum can present challenges for marine life and particularly becomes a problem when it collects along coastlines and rots, as shown here in Cancun in 2015. Image Credits: Michael Owen.

“The scale of these blooms is truly enormous, making global satellite imagery a good tool for detecting and tracking their dynamics through time,” said Woody Turner, manager of the Ecological Forecasting Program at NASA Headquarters in Washington.

Chuanmin Hu of the USF College of Marine Science, who led the study, has studied Sargassum using satellites since 2006. Hu spearheaded the work with first author Dr. Mengqiu Wang, a postdoctoral scholar in his Optical Oceanography Lab at USF. The team included others from USF, Florida Atlantic University, and Georgia Institute of Technology. The data they analyzed from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) between 2000-2018 indicates a possible regime shift in Sargassum blooms since 2011.

In the satellite imagery, major blooms occurred in every year between 2011 and 2018 except 2013. This information, coupled with field measurements, suggests that no bloom occurred in 2013 because the seed populations of Sargassum measured during winter of 2012 were unusually low, Wang said.

Images above: (Left) An unhealthy amount of Sargassum off Big Pine Key in the lower Florida Keys. Credit: Brian Lapointe, Ph.D., Florida Atlantic University’s Harbor Branch Oceanographic Institute (Right) In patchy doses in the open ocean, Sargassum contributes to ocean health by providing habitat for marine life. Dr. Mengqiu Wang was performing field work in the Gulf of Mexico last year when she saw dolphins seeming to enjoy their foray through the Sargassum. Images Credit: Mengqiu Wang.

Before 2011, most of the free floating Sargassum in the ocean was primarily found in patches around the Gulf of Mexico and Sargasso Sea. The Sargasso Sea is located on the western edge of the central Atlantic Ocean and named after its popular algal resident. In patchy doses in the open ocean, Sargassum contributes to ocean health by providing habitat for turtles, crabs, fish, and birds and, like other plants, producing oxygen via photosynthesis. But too much of this seaweed can crowd out marine species, especially near the coast.

In 2011, Sargassum populations started to explode in places it hadn’t been before, like the central Atlantic Ocean, and then it arrived in gargantuan gobs that suffocated shorelines and introduced a new nuisance for local environments and economies.

“The ocean’s chemistry must have changed in order for the blooms to get so out of hand,” Hu said. Sargassum reproduces from fragments of the parent plant, and it probably has several initiation zones around the Atlantic Ocean. It grows faster when nutrient conditions are favorable, and when its internal clock ticks in favor of reproduction.

The team identified key factors that are critical to bloom formation: a large seed population in the winter left over from a previous bloom, nutrient input from West Africa upwelling in winter, and nutrient input in the spring or summer from the Amazon River. Such discharged nutrients may have increased in recent years due to increased deforestation and fertilizer use, though Hu noted that the evidence for nutrient enrichment is preliminary and based on limited available data, and the team needs more research to confirm this hypothesis. In addition, Sargassum only grows well when salinity is normal and surface temperatures are normal or cooler.

Image above: The Great Atlantic Sargassum Belt in July 2018.Scientists used NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua satellites to discover the Great Atlantic Sargassum Belt (GASB), which started in 2011. It has occurred every year since, except 2013, and often stretches from the west coast of Africa to the Gulf of Mexico. Image Credits: NASA/Earth Observatory. Data provided by Mengqiu Wang and Chuanmin Hu, USF College of Marine Science.

“Earth’s ocean biogeochemistry is changing in response to natural and human forcings. The Great Atlantic Sargassum Belt suggests that we may be witnessing ecosystem shifts in our ocean that could have important implications for marine organisms and ecosystem services, which humans depend on,” said Dr. Paula Bontempi, who manages NASA’s Ocean Biology and Biogeochemistry Program and serves as acting deputy director of NASA’s Earth Science Division at NASA Headquarters.

«This is all ultimately related to climate change, as climate affects precipitation and ocean circulation and even human activities [that can lead to Sargassum blooms], but what we’ve shown is that these blooms do not occur because of increased water temperature,” Hu said. “They are probably here to stay.”

This work was funded by several programs in NASA’s Earth Science Division, NOAA RESTORE Science Program, the JPSS/NOAA Cal/Val project, the National Science Foundation, and by a William and Elsie Knight Endowed Fellowship.

Related links:

Aqua Satellite: https://www.nasa.gov/mission_pages/aqua/index.html

Terra Satellite: http://www.nasa.gov/mission_pages/terra/index.html

Images (mentioned), Text, Credits: NASA/Sara Blumberg/Earth Science News Team, by Ellen Gray.

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Damascus citadel restoration in progress, UNESCO to decide fate of Syrian heritage sites

In the Middle Ages, the Syrian city of Damascus was the nerve centre of a thriving craft industry, specializing in swords and lace.

Damascus citadel restoration in progress, UNESCO to decide fate of Syrian heritage sites
A man walks past residential buildings in Damascus, Syria
[Credit: Yamam Al Shaar/Reuters]

But since civil war broke out in 2011 the country has been left picking up the pieces. Today, archaeological digs have restarted and new excavations are underway in the Damascus Citadel, located in the northwest corner of Old Damascus.

The citadel consists of 12 towers, with three main gates. The towers contain several layers — a testimony to the various rulers and kings who made modifications to fortify the structures.

The archaeological drive on the citadel is focused on uncovering the Emirate’s house — the historic home of the ruler of Damascus and other areas in the Levante.

The UNESCO World Heritage Committee is meeting in Azerbaijan from June 30 to July 10 to examine 36 nominations for inscription on the list of World Heritage sites. It will also decide which sites are «in danger».

The destruction and reconstruction of Damascus citadel

Over the years, the citadel has seen its share of misfortune. It was hit by several earthquakes and started to fall into disrepair in the 19th century, used as a military barracks and prison until 1984.

Damascus citadel restoration in progress, UNESCO to decide fate of Syrian heritage sites
People walk at Marjeh Square in Damascus, Syria
[Credit: Yamam Al Shaar/Reuters]

Edmond Aji, head of the Damascus citadel enhancement project, said: «The excavations and archaeological research in the Citadel of Damascus are focused on these periods to study the mechanisms of the emirate, where only very rare ruins and few buildings are left.»

Aji is convinced that the site has not yet revealed all its secrets to archaeologists. «There will be a lot of surprises and important archaeological discoveries in the near future,» he said.

After the war erupted, tourists stopped visiting. Aji hopes that the new discoveries will attract visitors.

«Listing the citadel site on the international heritage list attracts tourists, scientists and researchers,» he said.

«We hope to preserve it now, In the past many destructions took place and I hope it returns to the state in which it used to be,» said visitor Yara Bara.

The ancient city of Damascus

For centuries, the citadel of Damascus stood guard over the Syrian city. Several generations of kings of sultans made military fortifications.

The city grew around its ramparts, which were fortified by several generations of kings and sultans. It had for its neighbour the historic Al-Hamidiyeh souq (market).
UNESCO’s heritage committee took note of its significance and declared the ancient city of Damascus a world heritage site in 1979, placing it alongside five other monuments in one of the oldest cities on Earth: The site of Palmyra; Ancient City of Bosra; Ancient City of Aleppo; Crac des Chevaliers and Qal’at Salah El-Din; the ancient villages of Northern Syria.

More than three decades later, a civil war broke out in Syria, damaging or destroying all of these heritage sites. UNESCO put them on the «in danger» list in 2013, intending to mobilize support for safeguarding them. These properties are recognised by the international community as being of «outstanding universal value for humanity as a whole,» according to UNESCO.

Author: Sukhada Tatke | Source: EuroNews [July 05, 2019]



Dig reveals bull sacrifices took place in ancient Selinunte

Professor Clemente Marconi of New York University on Thursday presented the results and discoveries of the 13th international archaeological dig in the Selinunte Acropolis, conducted by NYU and the University of Milan in collaboration with the archaeological park in western Sicily.

Dig reveals bull sacrifices took place in ancient Selinunte
Aerial view of Temple C at Selinute [Credit: WikiCommons]

Particularly important were the findings of a votive deposit of perfectly preserved red deer antlers (Cervus Elaphus) and two large adult bull horns (Bos Taurus). The remains are the first archaeological evidence of bull sacrifice in Selinunte.

Dig reveals bull sacrifices took place in ancient Selinunte
View of the excavations at the Sanctuary of Selinute [Credit: ANSA]

Marconi led the dig, in which over 50 students and experts from eight countries participated. The seminar and a guided tour of the dig site were organised as part of the «Worksites of Knowledge» project sponsored by the new director of the Selinunte archaeological park, architect Bernardo Agrò.

Dig reveals bull sacrifices took place in ancient Selinunte
Two pylon holes used for lifting the blocks during the construction of Temple R
and a perfectly preserved hollow libation altar [Credit: ANSA]

Agrò previously organised and directed similar seminars and tours at Medieval and modern monuments in other areas of Sicily.

Dig reveals bull sacrifices took place in ancient Selinunte
Votive deposit of perfectly preserved red deer antlers (Cervus Elaphus)
[Credit: ANSA]

This year’s Selinunte dig focused on deepening two trenches that were opened last year along the southern side of Temple R and between the western side of Temple R and the southern side of Temple C.

Dig reveals bull sacrifices took place in ancient Selinunte
Horns of a large adult bull (Bos Taurus) [Credit: ANSA]

The dig produced important results regarding the most ancient phases in which the large urban sanctuary was inhabited, and regarding activities associated with the construction of Temple R and Temple C.

Source: ANSA [July 05, 2019]



Cave droplets provide window into past climates

In the first ever global analysis of cave drip water, an international team, led by Andy Baker at UNSW Australia and including scientists from Cardiff University, have explored how stalagmites and stalactites can show how groundwater resources have recharged in the past.

Cave droplets provide window into past climates
The chemistry of drip waters that form stalagmites and stalactites in caves around the world have
given researchers an insight into our past climate [Credit: Cardiff University]

Groundwater, found underground in the cracks and pore spaces in rocks and sediments, is the largest source of usable freshwater in the world, and is relied on by more than two billion people as a source of drinking and irrigation water.

Groundwater resources are replenished predominantly through rainfall in a process known as recharge. At the same time, water exits or discharges from groundwater resources into lakes, streams and oceans to maintain an overall balance.

If there is a change in recharge, for example due to a reduction in rainfall as a result of climate change, the levels of water in the ground will begin to change until a new balance is achieved.

However, questions remain about how groundwater will be specifically impacted by future climate change, and where and when any changes will take place.

Though it has historically been difficult to determine past groundwater changes, scientists have recently made progress using new methods involving stalactites and stalagmites.

The oxygen isotope composition of stalagmites and stalactites found in caves can hold valuable clues about our past climate.

This oxygen comes from the water dripping from the stalactites and onto the stalagmites. The drip water originally comes from rainfall, providing a direct link to the surface climate.

Understanding the extent to which the oxygen isotopic composition of drip water is related to rainfall is a fundamental research question which will unlock the full climate potential of stalagmites and stalactites.

In their study, which has been published in Nature Communications, the team explored 163 sites from 39 caves on five continents, comparing the oxygen isotope composition of drip water to that of rainfall and groundwater recharge.

In cool climates, cave drip water oxygen isotope composition was similar to that of rainfall, meaning that stalagmite oxygen isotopes might best preserve past rainfall in these regions.

In warmer climates, and strongly seasonal climates, cave drip water oxygen isotope composition was similar to that of modelled groundwater recharge, meaning the records are more likely to preserve a record of past groundwater recharge.

Dr Mark Cuthbert, from Cardiff University’s School of Earth and Ocean Sciences, and co-author of the study, said: «These results are particularly important for interpreting records of past groundwater recharge from stalagmites in dryland regions. This can help us understand the relationship between climate variability and water resources in naturally water scarce parts of the world and inform water management strategies in the context of climate change.»

Source: Cardiff University [July 08, 2019]



Ancient Saharan seaway shows how Earth’s climate and creatures can undergo extreme...

A new paper to be published in the Bulletin of the American Museum of Natural History integrates 20 years of research by a diverse scientific team and describes the ancient Trans-Saharan Seaway of Africa that existed 50 to 100 million years ago in the region of the current Sahara Desert. Led by Maureen O’Leary, Professor of Anatomical Sciences at the Renaissance School of Medicine at Stony Brook University, the paper is a comprehensive synthesis and contains the first reconstructions of extinct aquatic species in their habitats along the seaway and places in context massive climate and sea level changes that can occur on Earth.

Ancient Saharan seaway shows how Earth's climate and creatures can undergo extreme change
During the Late Cretaceous-early Paleogene, the shallow waters of the Trans-Saharan Seaway waters were
teeming with aquatic species which ranged from small mollusks to giant sea snakes and catfish
[Credit: © Carl Buell]

The region now holding the Sahara Desert was once under water, in striking contrast to the present-day arid environment. This dramatic difference in climate over time is recorded in the rock and fossil record of West Africa during a time range that extends through the Cretaceous-Paleogene (KPg) boundary. West Africa was bisected by a shallow saltwater body that poured onto continental crust during a time of high global sea level. The Bulletin paper involves an assessment and continued analysis of three expeditions led by Professor O’Leary (1999, 2003, and 2008) within rock exposures in the Sahara Desert in Mali, and subsequently the laboratory work of the fossil finds in the region.
«Fossils found on the expeditions indicate that the sea supported some of the largest sea snakes and catfish that ever lived, extinct fishes that were giants compared to their modern day relatives, mollusk-crushing fishes, tropical invertebrates, long-snouted crocodilians, early mammals and mangrove forests,» explained Professor O’Leary, who is also a Research Associate in the Division of Paleontology, American Museum of Natural History. «Because the seaway changed in size and geography frequently, we propose that it may have resulted in ‘islands of water’ that stimulated species gigantism.»

The paper contains the first reconstructions of ancient relatives of elephants and large apex predators such as sharks, crocodilians and sea snakes.

«With our analysis and new technologies, such as a computer-aided map of the seaway, our work is an important step toward increasing our understanding of the KPg boundary event, the time of non-avian dinosaur extinction,» said Professor O’Leary.

She and colleagues point out that the paper places in context climate and sea level changes that can occur on Earth.

For example, scientists currently predict that global warming will result in the sea rising two meters by the end of the 21st century. The study in the Bulletin describes how, in the Late Cretaceous, the time under study, sea level rise far exceeded that which is predicted by human-induced climate change. In the Late Cretaceous sea level was 300m higher than present — 40 percent of current land was under water, which is very different from today. This information underscores the dynamic nature of Earth.

Professor O’Leary explained that scientists do not have detailed stratigraphic terrestrial/near shore sections with fossils on every continent to examine exactly how the KPg boundary unfolded globally. There is only one good nearshore or terrestrial section with vertebrate fossils in the western United States. The expeditions in Mali, she added, created a new section, which is imperfect, missing some of the earliest Paleogene yet contributes to a better understanding of global events 50 to 100 million years ago.

The expeditions spanning 20 years involved Professor O’Leary and numerous colleagues internationally to excavate the fossils and conduct the research. The collaborative research team consists of paleontologists and geologists from the United States, Australia and Mali.

«Few paleontologists had worked the region, given its remoteness and scorching 125 degree F temperatures. The shifting sand dunes made it difficult to find rocky outcrops, and worse still, a flash rain storm flooded the roadways making navigation nearly impossible,» said Leif Tapanila, PhD, Professor of Geosciences at Idaho State University and a co-author of the paper. «These expeditions could not have succeeded without the experience of local Malian drivers and guides, and I was amazed by the quality and diversity of marine fossils we found in the Sahara Desert.»

Source: American Museum of Natural History [July 08, 2019]



Lead pollution in Arctic ice shows economic impact of wars and plagues for past 1,500...

How did events like the Black Death plague impact the economy of Medieval Europe? Particles of lead trapped deep in Arctic ice can tell us.

Lead pollution in Arctic ice shows economic impact of wars and plagues for past 1,500 years
Joe McConnell, Ph.D, the study’s lead author, and Nathan Chellman, a doctoral student at DRI
and coauthor on the study, examine an ice core in DRI’s Ultra-Trace Ice Core Chemistry
Laboratory in Reno, Nevada [Credit: DRI]

Commercial and industrial processes have emitted lead into the atmosphere for thousands of years, from the mining and smelting of silver ores to make currency for ancient Rome to the burning of fossil fuels today. This lead pollution travels on wind currents through the atmosphere, eventually settling on places like the ice sheet in Greenland and other parts of the Arctic.

Because of lead’s connection to precious metals like silver and the fact that natural lead levels in the environment are very low, scientists have found that lead deposits in layers of Arctic ice are a sensitive indicator of overall economic activity throughout history.

In a new study published in the Proceedings of the National Academy of Sciences, researchers from the Desert Research Institute (DRI), the University of Oxford, NILU — Norwegian Institute for Air Research, the University of Copenhagen, the University of Rochester, the Alfred Wegener Institute for Polar and Marine Research used thirteen Arctic ice cores from Greenland and the Russian Arctic to measure, date, and analyze lead emissions captured in the ice from 500 to 2010 CE, a period of time that extended from the Middle Ages through the Modern Period to the present.

This work builds on a study published by some of the same researchers in 2018, which showed how lead pollution in a single ice core from Greenland tracked the ups and downs of the European economy between 1100 BCE and 800 CE, a period which included the Greek and Roman empires.

«We have extended our earlier record through the Middle Ages and Modern Period to the present,» explained Joe McConnell, Ph.D., lead author on the study and Director of DRI’s Ultra-Trace Ice Core Chemistry Laboratory in Reno, Nevada. «Using an array of thirteen ice cores instead of just one, this new study shows that prior to the Industrial Revolution, lead pollution was pervasive and surprisingly similar across a large swath of the Arctic and undoubtedly the result of European emissions. The ice-core array provides with amazing detail a continuous record of European — and later North American — industrial emissions during the past 1500 years.»

«Developing and interpreting such an extensive array of Arctic ice-core records would have been impossible without international collaboration,» McConnell added.

Lead pollution in Arctic ice shows economic impact of wars and plagues for past 1,500 years
Locations of the 13 Arctic ice-core drilling sites, as well as ancient and medieval lead/silver mines throughout Europe.
Atmospheric modeling shows the impact of emissions from different regions on pollution recorded in the Arctic
ice cores. The Russian Arctic, for example, is relatively more sensitive to emissions from mines in eastern
Europe, while North Greenland is relatively more sensitive to emissions from western Europe
[Credit: Desert Research Institute]

The research team found that increases in lead concentration in the ice cores track closely with periods of expansion in Europe, the advent of new technologies, and economic prosperity. Decreases in lead, on the other hand, paralleled climate disruptions, wars, plagues, and famines.

«Sustained increases in lead pollution during the Early and High Middle Ages (about 800 to 1300 CE), for example, indicate widespread economic growth, particularly in central Europe as new mining areas were discovered in places like the German Harz and Erzgebirge Mountains, «McConnell noted. «Lead pollution in the ice core records declined during the Late Middle Ages and Early Modern Period (about 1300 to 1680 Ce) when plague devastated those regions, however, indicating that economic activity stalled.»

Even with ups and downs over time due to events such as plagues, the study shows that increases in lead pollution in the Arctic during the past 1500 years have been exponential.

«We found an overall 250 to 300-fold increase in Arctic lead pollution from the start of the Middle Ages in 500 CE to 1970s,» explained Nathan Chellman, a doctoral student at DRI and coauthor on the study. «Since the passage of pollution abatement policies, including the 1970 Clean Air Act in the United States, lead pollution in Arctic ice has declined more than 80 percent.»

«Still, lead levels are about 60 times higher today than they were at the beginning of the Middle Ages,» Chellman added.

This study included an array of ice cores and the research team used state-of-the-art atmospheric modeling to determine the relative sensitivity of different ice-core sites in the Arctic to lead emissions.

Lead pollution in Arctic ice shows economic impact of wars and plagues for past 1,500 years
Lead pollution found in 13 ice cores from three different regions of the Arctic (North Greenland,
South Greenland, and the Russian Arctic) from 200 BCE to 2010 CE. Increases in lead deposition
coincided with times of economic prosperity, such as the Industrial Revolution in the mid-19th century.
Dramatic declines in lead pollution followed crises such as the Black Death Plague Pandemic starting
about 1347 CE, as well as pollution abatement policies such as the 1970 U.S. Clean Air Act
[Credit: Desert Research Institute]

«Modeling shows that the core from the Russian Arctic is more sensitive to European emissions, particularly from eastern parts of Europe, than cores from Greenland,» explained Andreas Stohl, Ph.D., atmospheric scientist at NILU and coauthor on the study. «This is why we found consistently higher levels of lead pollution in the Russian Arctic core and more rapid increases during the Early and High Middle Ages as mining operations shifted north and east from the Iberian Peninsula to Great Britain and Germany.»
The combination of expertise on this study is unique, continuing a collaboration between researchers in fields as different as ice-core chemistry and economic history. These results, the team argues, are a testament to the benefits of interdisciplinary collaboration.

«What we’re finding is interesting not just to environmental scientists who want to understand how human activity has altered the environment,» said Andrew Wilson, Ph.D., Professor of the Archaeology of the Roman Empire at Oxford and co-author on the study. «These ice-core records also are helping historians to understand and quantify the ways that societies and their economies have responded to external forces such as climate disruptions, plagues, or political unrest.»

Source: Desert Research Institute [July 08, 2019]



Remodelling ruins to preserve rural heritage

Luzzone, located some 2,150 meters high in Ticino’s Malvaglia valley, was a small hamlet used by mountain herders and their livestock. It was abandoned in the 1950s and today lies mostly in ruins. But this past weekend, the workshop’s 120 participants teamed up to restore and remodel the ancient structures.

Remodelling ruins to preserve rural heritage
Around 120 architecture students, including some from EPFL, took part in a unique workshop on Mount Luzzone
in Ticino on 6–7 July 2019. They remodeled the ruins of an ancient hamlet in order to preserve an
 important – and fading – element of this Alpine heritage [Credit: EPFL/Patrick Giromini]

Of the hamlet’s original ten buildings, one is still being used, one is falling down and six others are in ruins. «These functional buildings were made entirely of stone and measured just four meters long by four meters wide. They served as stables and as mountain huts for herders during the summer and were typical of life in the Alps, and especially Ticino, at the time,» says Patrick Giromini, a Ph.D. student in architecture and assistant at EPFL’s Arts of Sciences Laboratory (LAPIS) and one of the workshop organizers.

Remodeling, not rebuilding

The students first identified the original layout of the buildings’ walls—which are now nothing more than piles of stones. Any stones sitting outside the perimeter of the hamlet were carried back to their original structures and used to rebuild some of the walls. This helped restore the volumes of the original buildings. Rather than reconstructing the buildings, however, the students put their creative juices to work in order to remodel them.

Ticino architect and EPFL graduate Martino Pedrozzi (pedrozzi.com) came up with the idea for the project. Currently a guest lecturer at the Mendrisio Academy of Architecture at the Università della Svizzera Italiana (USI), he has been involved in this kind of remodeling work for over 20 years.

«There are many examples of this rural heritage scattered throughout the Alps, not just in Ticino. The question is, what should we do with these ruins? Given their remote locations, they are virtually useless. But by remodeling them, we can give them a purpose: to serve as landmarks. That is a function they once had but have since lost,» he says.

Remodelling ruins to preserve rural heritage

Remodelling ruins to preserve rural heritage
Before and after photos of a similar project in Sceru (Ticino), 2015
[Credit: EPFL/Pino Brioschi]

The students’ project therefore aimed not just at preserving the region’s heritage, but also at bringing it to people’s attention and underscoring the importance of our rural memory. «It also introduced the students to the rigors of rural life. Every summer, for example, the farmers had to repair snow damage,» says Giromini.

Surprisingly popular

The workshop was run jointly by three Swiss architecture schools: the Mendrisio Academy of Architecture at USI, EPFL’s architecture department and ETH Zurich’s Institute for Spatial and Landscape Development. This was the first time these three schools teamed up for a workshop. The project also received support from the municipality of Serravalle, where the ruins are located.

«We expected around 30 students to sign up—ten from each school. But we ended up with 120 people on the registration list. We never thought our workshop would be so popular!» says Nicola Braghieri, head of EPFL’s architecture department and of LAPIS.

An unforgettable experience

The workshop also gave the students a chance to team up with peers from a variety of backgrounds. They travelled from Mendrisio, Lausanne and Zurich to the foot of Mount Luzzone, which they hiked up for 90 minutes to reach the ruins. After spending the day remodeling the hamlet, they camped out there for the night.

«A workshop like this is always a unique experience and I enjoy them every time,» says Agathe Loeb, a Master’s student in architecture at EPFL and program participant. «You usually meet people from different schools and even different countries, who bring an entirely different perspective on architecture. Speaking with them can be really interesting—it opens your mind and breaks you out of your routine ways of thinking.» Not to mention that the entire experience—from performing back-breaking work to camping out in rustic conditions—is bound to leave a lasting impression.

While this particular workshop involved remodeling stone structures in Ticino, the same format could be used for just about any kind of abandoned heritage site in the Alps.

«At LAPIS, we have been studying the preservation of mountain huts and pastures for five years now, mainly in the canton of Valais. But since many of those structures are made from wood in addition to stone, we would have to adapt the workshop format slightly. It’s definitely something worth considering,» says Braghieri.

Author: Nathalie Jollien | Source: Ecole Polytechnique Federale de Lausanne [July 09, 2019]



New Kinord Prehistoric Hut Circles, The Cairngorms, Scotland, 6.7.19.

New Kinord Prehistoric Hut Circles, The Cairngorms, Scotland, 6.7.19.

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Sunhoney Prehistoric Recumbent Stone Circle, Aberdeenshire, 6.7.19.

Sunhoney Prehistoric Recumbent Stone Circle, Aberdeenshire, 6.7.19.

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