пятница, 14 сентября 2018 г.

Did somebody say space laser?

We’re set to launch ICESat-2, our most advanced laser instrument of its kind, into orbit around Earth on Sept. 15. The Ice, Cloud and land Elevation Satellite-2 will make critical observations of how ice sheets, glaciers and sea ice are changing over time, helping us better understand how those changes affect people where they live. Here’s 10 numbers to know about this mission:


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One Space Laser


There’s only one scientific instrument on ICESat-2, but it’s a marvel. The Advanced Topographic Laser Altimeter System, or ATLAS, measures height by precisely timing how long it takes individual photons of light from a laser to leave the satellite, bounce off Earth, and return to ICESat-2. Hundreds of people at our Goddard Space Flight Center worked to build this smart-car-sized instrument to exacting requirements so that scientists can measure minute changes in our planet’s ice.


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Sea ice is seen in front of Apusiaajik Glacier in Greenland. Credit: NASA/JPL-Caltech/Jim Round



Two Types of Ice


Not all ice is the same. Land ice, like the ice sheets in Greenland and Antarctica, or glaciers dotting the Himalayas, builds up as snow falls over centuries and forms compacted layers. When it melts, it can flow into the ocean and raise sea level. Sea ice, on the other hand, forms when ocean water freezes. It can last for years, or a single winter. When sea ice disappears, there is no effect on sea level (think of a melting ice cube in your drink), but it can change climate and weather patterns far beyond the poles.


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3-Dimensional Earth


ICESat-2 will measure elevation to see how much glaciers, sea ice and ice sheets are rising or falling. Our fleet of satellites collect detailed images of our planet that show changes to features like ice sheets and forests, and with ICESat-2’s data, scientists can add the third dimension – height – to those portraits of Earth.


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Four Seasons, Four Measurements


ICESat-2’s orbit will make 1,387 unique ground tracks around Earth in 91 days – and then start the same ground pattern again at the beginning. This allows the satellite to measure the same ground tracks four times a year and scientists to see how glaciers and other frozen features change with the seasons – including over winter.


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532 Nanometer Wavelength


The ATLAS instrument will measure ice with a laser that shines at 532 nanometers – a bright green on the visible spectrum. When these laser photons return to the satellite, they pass through a series of filters that block any light that’s not exactly at this wavelength. This helps the instrument from being swamped with all the other shades of sunlight naturally reflected from Earth.


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Six Laser Beams


While the first ICESat satellite (2003-2009) measured ice with a single laser beam, ICESat-2 splits its laser light into six beams – the better to cover more ground (or ice). The arrangement of the beams into three pairs will also allow scientists to assess the slope of the surface they’re measuring.


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Seven Kilometers Per Second


ICESat-2 will zoom above the planet at 7 km per second (4.3 miles per second), completing an orbit around Earth in 90 minutes. The orbits have been set to converge at the 88-degree latitude lines around the poles, to focus the data coverage in the region where scientists expect to see the most change.


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800-Picosecond Precision


All of those height measurements come from timing the individual laser photons on their 600-mile roundtrip between the satellite and Earth’s surface – a journey that is timed to within 800 picoseconds. That’s a precision of nearly a billionth of a second. Our engineers had to custom build a stopwatch-like device, because no existing timers fit the strict requirements.


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Nine Years of Operation IceBridge


As ICESat-2 measures the poles, it adds to our record of ice heights that started with the first ICESat and continued with Operation IceBridge, an airborne mission that has been flying over the Arctic and Antarctic for nine years. The campaign, which bridges the gap between the two satellite missions, has flown since 2009, taking height measurements and documenting the changing ice.


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10,000 Pulses a Second


ICESat-2’s laser will fire 10,000 times in one second. The original ICESat fired 40 times a second. More pulses mean more height data. If ICESat-2 flew over a football field, it would take 130 measurements between end zones; its predecessor, on the other hand, would have taken one measurement in each end zone.


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And One Bonus Number: 300 Trillion


Each laser pulse ICESat-2 fires contains about 300 trillion photons! Again, the laser instrument is so precise that it can time how long it takes individual photons to return to the satellite to within one billionth of a second. 


Learn more about ICESat-2: https://www.nasa.gov/icesat-2


Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.


37 ancient rock tombs discovered in Central China

Recently, 37 ancient rock tombs were discovered in Yangpitan, Yunxi county, Central China’s Hubei province.


37 ancient rock tombs discovered in Central China










37 ancient rock tombs discovered in Central China
Archaeologists access the excavation area on a cliff by rock climbing to the site in Yangpitan,
Yunxi county, Central China’s Hubei Province [Credit: Zhang Jianbo/ChinaDaily]

This is the first time for archaeologists carry out large-scale excavations by rock climbing along the Hanjiang River, Central China’s Hubei province.


37 ancient rock tombs discovered in Central China










37 ancient rock tombs discovered in Central China
An archaeologists at work on a rock tomb in Yangpitan, Yunxi county, Central China’s Hubei Province
[Credit: Zhang Jianbo/ChinaDaily]

From the 37 tombs, human bones, and items from the Tang Dynasty (618-907), such as copper coins, material beads, celadon fragments and inscription bricks, have been unearthed.


Source: ECNS [September 12, 2018]



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Trees reveal the evolution of environmental pollution

In an article published in the journal Environmental Pollution, Brazilian researchers showed that tree species Tipuana tipu have been successfully employed as a marker of atmospheric pollution by heavy metal and other chemical compounds in Sao Paulo, Brazil’s biggest metropolis.











Trees reveal the evolution of environmental pollution
The chemical composition of the tree’s growth rings reflects the levels of heavy metals in the soil year by year
[Credit: Giuliano Maselli Locosselli]

This Bolivia-native species commonly known as tipuana tree is ubiquitous in the city. Researchers at the University of São Paulo’s Bioscience Institute (IB-USP) and Medical School (FM-USP), in collaboration with colleagues at the University of Campinas (IB-UNICAMP), have considered T. tipu the most suitable tree for measuring environmental pollution levels in São Paulo over the long term by analyzing the chemical composition of tree bark and growth rings.


Tests were carried out in order to compare the performance of three of the most common tree species in the city: privet (Ligustrum sp.), sibipiruna or partridgewood (Caesalpinia pluviosa), and tipuana.


With the support of São Paulo Research Foundation – FAPESP via a Thematic Project , a regular research grant and a postdoctoral research scholarship, the research attested a reduction in the levels of pollution by cadmium, copper, nickel and lead in the west of the city in the last 30 years.


The roots of the tipuana tree absorb heavy metals and other chemicals that are present in the atmosphere and fall to the ground in rainwater. These chemicals are transported in sap by the tree’s xylem cells and stored in the wood of its growth rings – those concentric circles visible in a cross-section of the trunk.


Each growth ring represents a year of the tree’s life. The more recent rings are wider and farther from the center. Those closest to the center are narrower. The chemical composition of the tree’s growth rings reflects the levels of heavy metals in the soil year by year, and the results can be compared to determine how this type of pollution has varied on a scale of decades.


“If a tree is 50 years old, for example, it will tell the story of pollution in the city during that period,” said Giuliano Maselli Locosselli, a postdoctoral researcher at IB-USP and first author of the study.


All the while Tipuana bark analysis shows the levels of atmospheric chemicals that have been passively deposited in this external part of the trunk.


By measuring the levels of heavy metals in samples of bark from trees still standing in different neighborhoods of the city, the researchers can map spatial variations in these levels on a scale of years.


“It’s easier to obtain samples of bark than annual growth rings, and the chemical analysis of bark is less costly, so we can analyze samples from many trees and cover a large area”, said the FAPESP scholarship holder. “The result is a map of pollution by heavy metals and other chemical elements throughout the city.”


Falling levels of pollution by heavy metals


The researchers conducted an initial study in which they measured the levels of cadmium, copper, mercury, nickel, sodium, lead and zinc in rings from two tipuana specimens growing in the gardens of the University of São Paulo’s Medical School in the west of the city’s central region. Their goal was to analyze the temporal changes in the levels of heavy metal pollution in this part of São Paulo.


The two trees used in this study were 35 years old. Samples were taken from their growth rings using an instrument called a Pressler increment borer, which has a hollow auger bit and is designed to extract a cylindrical section of wood tissue from a living tree throughout its radius with relatively minor injury to the plant itself.


“The procedure can be compared to a tree biopsy,” Locosselli said.


The 15-mm annual growth ring samples were sent to Marco Aurelio Zezzi Arruda, a professor at the University of Campinas’s Chemistry Institute (IQ-UNICAMP). There, the samples were scanned by laser ablation coupled with mass spectrometry, generating software-processed images for chemical analysis.


The researchers selected the cells of interest and performed a continuous analysis of all the annual growth rings to measure the levels of heavy metals absorbed by the trees in each year of their lives.


The data analysis pointed to a significant reduction in pollution by cadmium, copper, nickel and lead in the last three decades in the part of the city inhabited by the sampled tipuana trees, as well as a more moderate decrease in the levels of sodium and zinc.


“The falling levels of lead reflected the gradual elimination of this chemical element from the composition of Brazilian gasoline,” said Marcos Buckeridge, coprincipal investigator at the FAPESP Thematic Project and a coauthor of the study.


“The downtrend in cadmium, copper and nickel pollution probably reflects enhanced vehicle efficiency and deindustrialization in São Paulo,” Buckeridge said.


Tetraethyl lead was used worldwide as an antiknock agent in automotive gasoline for much of the twentieth century to improve engine performance and reduce wear. The resulting release of lead into the atmosphere via vehicle exhaust was a severe health hazard.


Brazil banned the addition of tetraethyl lead to automotive gasoline in 1988.


The main sources of cadmium in ambient air pollution are the electronic appliance industry, pigments used in paint and dye, batteries, photography, lithography, fireworks, plastic, semiconductors, solar cells, fuels, urban garbage, tire rubber, and electroplating. The main sources of copper emissions are the burning of urban and industrial waste, metal alloy casting, and pesticides.


“The levels of these chemical elements in São Paulo’s ambient air have fallen in recent decades owing to deindustrialization,” Locosselli said.


Author: Elton Alisson | Source: Fundação de Amparo à Pesquisa do Estado de São Paulo [September 13, 2018]



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Famous theory of the living Earth upgraded to ‘Gaia 2.0’

A time-honoured theory into why conditions on Earth have remained stable enough for life to evolve over billions of years has been given a new, innovative twist.











Famous theory of the living Earth upgraded to 'Gaia 2.0'
Credit: NASA

For around half a century, the ‘Gaia’ hypothesis has provided a unique way of understanding how life has persisted on Earth.


It champions the idea that living organisms and their inorganic surroundings evolved together as a single, self-regulating system that has kept the planet habitable for life – despite threats such as a brightening Sun, volcanoes and meteorite strikes.


However, Professor Tim Lenton from the University of Exeter and famed French sociologist of science Professor Bruno Latour are now arguing that humans have the potential to ‘upgrade’ this planetary operating system to create “Gaia 2.0”.


They believe that the evolution of both humans and their technology could add a new level of “self-awareness” to Earth’s self-regulation, which is at the heart of the original Gaia theory.


As humans become more aware of the global consequences of their actions, including climate change, a new kind of deliberate self-regulation becomes possible where we limit our impacts on the planet.


Professors Lenton and Latour suggest that this “conscience choice” to self-regulate introduces a “fundamental new state of Gaia” – which could help us achieve greater global sustainability in the future.


However, such self-aware self-regulation relies on our ability to continually monitor and model the state of the planet and our effects upon it.


Professor Lenton, Director of Exeter’s new Global Systems Institute, said: “If we are to create a better world for the growing human population this century then we need to regulate our impacts on our life support-system, and deliberately create a more circular economy that relies – like the biosphere – on the recycling of materials powered by sustainable energy.”


The original Gaia Theory was developed in the late 1960’s by James Lovelock, a British scientist and inventor. It suggested that both the organic and inorganic components of Earth evolved together as one single, self-regulating system which can control global temperature and atmospheric composition to maintain its own habitability.


The new perspective article is published in journal Science. It follows recent research, led by Professor Lenton, which offered a fresh solution to how the Gaia hypothesis works in real terms: Stability comes from “sequential selection” in which situations where life destabilises the environment tend to be short-lived and result in further change until a stable situation emerges, which then tends to persist.


Once this happens, the system has more time to acquire further properties that help to stabilise and maintain it – a process known as “selection by survival alone”.


Creating transformative solutions to the global changes that humans are now causing is a key focus of the University of Exeter’s new Global Systems Institute.


Source: University of Exeter [September 13, 2018]



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New genetics tool helps answer evolutionary questions

The age of big data is here. Thanks to innovations in genetic sequencing technology, scientists can now generate massive datasets describing the genomes of Earth’s diverse set of species. This ever-growing genomic encyclopedia has the capacity to reveal the forces shaping complex patterns of genetic variation between individuals, populations and species – if scientists can only unlock its secrets.











New genetics tool helps answer evolutionary questions
Credit: Michigan State University

Developing cutting-edge statistical tools that can handle these massive new datasets is a piece of the research puzzle, and new research from Michigan State University has just added a new tool for the modern genomic toolbox.


The method, called “conStruct” and featured in the current issue of Genetics, allows researchers to analyze complex patterns of genetic variation in large datasets with broad geographic sampling. It overcomes major shortcomings of previous methods and is free and publicly available worldwide.


“One of the first steps in the analysis of these genomic datasets is to describe and categorize variation into discrete populations, like you might find in range maps in a field guide,” said Gideon Bradburd, MSU population geneticist and lead author. “What often determines relatedness is geography. If you sample two organisms separated by a large distance, you often have to go farther back into the history of their pedigrees to find a shared ancestor.”


This leads to isolation by distance, a pattern that creates statistical challenges for anyone interested in cleanly describing variation within and between groups in their own study system, he added.


In the paper, Bradburd and his colleagues illustrate the utility of their new approach by applying it to genomic data collected on North American bears and poplar trees. For a better understanding, let’s look at the poplars, which are distributed throughout the northern hemisphere. Different species of poplar can be found near each other, and, where they overlap, they frequently hybridize.


Using conStruct, the research team was able to review the degree to which hybridization between the two poplar species has happened. They were also able to determine whether the only significant population boundary fell along the species boundary, and if there was substructuring within the species.


“Understanding the genetic relatedness of individuals is central to many important research fields, including conservation biology, human medicine, evolution and ecology, and agriculture,” Bradburd said. “With conStruct, scientists can home in on commonalities and discrepancies among populations with more accuracy. This can prove invaluable, especially in conservation efforts.”


And, of course, these genomic patterns will offer additional insights into human evolution.


For the next phase of this research, Bradburd’s team will attempt to take conStruct into the fourth dimension. They hope to add the ability to model historical or ancient DNA samples to learn how and why populations change – or are replaced by their neighbors – through time.


Source: Michigan State University [September 13, 2018]



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The walking dead: Fossils on the move can distort patterns of mass extinctions

Using the fossil record to accurately estimate the timing and pace of past mass extinctions is no easy task, and a new study highlights how fossil evidence can produce a misleading picture if not interpreted with care.


The walking dead: Fossils on the move can distort patterns of mass extinctions

The walking dead: Fossils on the move can distort patterns of mass extinctions










The walking dead: Fossils on the move can distort patterns of mass extinctions
These three samples of fossil mollusks all come from the same core, but reflect different environments. As sea levels
change and move habitats, animals follow. Taking these shifts into account when analyzing the fossil record
is crucial, researchers said [Credit: Daniele Scarponi]

Florida Museum of Natural History researchers used a series of 130-foot cores drilled from the Po Plain in northeastern Italy to test a thought experiment: Imagine catastrophe strikes the Adriatic Sea, swiftly wiping out modern marine life. Could this hypothetical mass extinction be reconstructed correctly from mollusks – hard-shelled animals such as oysters and mussels – preserved in these cores?


When they examined the cores, the results were “somewhat unnerving,” said Michal Kowalewski, Thompson Chair of Invertebrate Paleontology and the study’s principal investigator.


Paleontologists use the age of a species’ last-known fossil to estimate the timing of extinction. A sudden extinction in the Adriatic Sea today should leave the youngest remains of many mollusk species in the sediments currently forming on the shore and seabed, the “ground zero” of the hypothetical extinction event. But the team found only six of 119 mollusk species – all of which are still alive in the area – at the top of the cores. Instead, the last fossil examples of many of these species often appeared in clusters dotted throughout the cores, suggesting smaller bursts of extinctions over a longer timeline, not a single massive die-off.


Taken at face value, the cores presented a dramatically distorted record of both the timing and tempo of extinction, potentially calling into question some of the methods paleontologists commonly use to interpret past mass extinctions.











The walking dead: Fossils on the move can distort patterns of mass extinctions
These bars are sections of sediment from one of the cores drilled in the Po Plain in northeastern Italy,
about 45 miles south of Venice [Credit: Daniele Scarponi]

“We’re not saying you cannot study mass extinctions. You can,” Kowalewski said. “What we’re saying is that the nature of the geological record is complicated, so it is not trivial to decipher it correctly.”


The results of their analysis did not come as a complete surprise. Computer models designed by paleontologists Steven Holland and Mark Patzkowsky had made similar predictions about how the final resting place of fossils – influenced by species’ ecological preferences, sea level and the makeup of sedimentary basins – could skew patterns of mass extinction.


“This is, to my knowledge, the first empirical study to use the fossil record of living species to test these models rigorously and computationally, rather than theoretically,” Kowalewski said. “We know these species are still living in the Adriatic Sea, so we can be sure that their disappearance from the fossil record does not represent a true extinction.”


Paleontologists have been grappling with the complications of interpreting mass extinctions in the fossil record for several decades. Even the extinction of the dinosaurs was thought to be a gradual, drawn-out process until evidence of a lethal meteor impact emerged in 1980. The problem is a phenomenon known as the Signor-Lipps effect: Because the fossil record is incompletely sampled, the last-known fossil of a given species is almost certainly not the last member of that species, which muddles our ability to date extinctions.











The walking dead: Fossils on the move can distort patterns of mass extinctions
The numbers atop this landscape show where cores were drilled. The cores captured a snapshot of various
environments – such as coastal lagoons, swamps and deltas – not only horizontally across the current
geographic landscape but also at different depths, reflecting how the region has changed over time
[Credit: Nawrot et al. Proceedings of the Royal Society B]

Applied on a larger scale, the Signor-Lipps effect can make abrupt mass extinctions appear gradual. A common approach to correct for this effect is to assume that where fossils end up – and are later discovered – is random, and mathematically adjust estimates of extinction timing accordingly.


But it’s more complicated than that, Kowalewski said, because the fossil record is not created in a random way.


Climatic cycles trigger changes in sea level, causing shorelines to advance or recede and driving changes in environments. A beach may become a mudflat, for example, or a delta can turn into a coastal plain. Shifts in sea level can also affect sedimentation rates – how quickly mud and sand are deposited. These factors can cause last occurrences of fossils to cluster together and influence the probability of finding fossils in a given location.


When the researchers reordered the species represented in the cores from the Po basin according to their last occurrence, they noted several points at which many species appeared to vanish simultaneously. In reality, none of the species had gone extinct. They disappeared from a given site either because local environmental conditions changed, or they were simply missed during the sampling, said Rafal Nawrot, the study’s first author and a postdoctoral researcher in invertebrate paleontology at the Florida Museum.











The walking dead: Fossils on the move can distort patterns of mass extinctions
Thousands of years ago, this area was a shallow sea. As the Po River transported mud and sand to the Adriatic Sea,
the sea gave way to a river delta and then lagoons and marshes. These environmental changes are reflected
in the groups of fossils preserved below the surface [Credit: Daniele Scarponi]

The cores also depicted a false pattern of extinction, with the majority of offshore species disappearing in a single large “pulse” in the lower part of the cores and shallow-water and brackish species fading out in several smaller pulses. This is because species followed their preferred habitats as they shifted with changing sea levels. Deeper-water dwellers vanished first, as the local river delta started to expand into the Adriatic Sea, replacing open sea with coastal conditions. When shorelines advanced even farther, shallow-water species disappeared as well.


“It’s important to admit that fossil species – just like modern ones – have specific ecological requirements, which sounds obvious but is not always acknowledged,” Nawrot said.


Current methods may give researchers the illusion of precision but fail to account for these factors, which are crucial to correctly interpreting past extinction events, he said.


“If you apply methods based on the assumption of random fossilization, you get a precise estimate, but it may be wrong by millions of years,” Nawrot said. “Not only the pattern of extinction but also the timing of extinction would be wrongly interpreted, so this is quite important.”


While the findings are sobering, the situation is far from hopeless, Kowalewski said. When the team incorporated methods that accounted for species’ ecological preferences, distribution and abundance into the analysis, the results were a much closer approximation of what exists in the basin today.


“This provides us with an initial guideline of how to analyze these types of data to get a more realistic assessment of extinction events,” Kowalewski said. “Certainly, this is a work in progress.”


The researchers published their findings in the Proceedings of the Royal Society B.


Source: Florida Museum of Natural History [September 13, 2018]



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Geologists reveal ancient connection between England and France

The British mainland was formed from the collision of not two, but three ancient continental land masses, according to new research.











Geologists reveal ancient connection between England and France
Credit: European Space Agency

Scientists have for centuries believed that England, Wales and Scotland were created by the merger of Avalonia and Laurentia more than 400 million years ago.


However, geologists based at the University of Plymouth now believe that a third land mass – Armorica – was also involved in the process.


The findings are published in Nature Communications and follow an extensive study of mineral properties at exposed rock features across Devon and Cornwall.


They reveal a clear boundary running across the two counties, with areas north of it sharing their geological roots with the rest of England and Wales but everything south being geologically linked to France and mainland Europe.











Geologists reveal ancient connection between England and France
This graphic shows how the ancient land masses of Laurentia, Avalonia and Armorica
would have collided to create the countries of England, Scotland and Wales
 [Credit: University of Plymouth]

Among other things, scientists believe the research explains the abundance of tin and tungsten in the far South West of England – metals also found in Brittany and other areas of mainland Europe, but not so evident in the rest of the UK.


The research’s lead author, Lecturer in Igneous Petrology Dr Arjan Dijkstra, said: “This is a completely new way of thinking about how Britain was formed. It has always been presumed that the border of Avalonia and Armorica was beneath what would seem to be the natural boundary of the English Channel. But our findings suggest that although there is no physical line on the surface, there is a clear geological boundary which separates Cornwall and south Devon from the rest of the UK.”


For the research, Dr Dijkstra and Masters student Callum Hatch (now working at the Natural History Museum) visited 22 sites in Devon and Cornwall that were left exposed following geological events, such as underground volcanic eruptions. These took place around 300 million years ago and brought magma from depths of 100 km to the Earth’s surface.


They took rock samples from each site, subjecting them to detailed chemical analysis in the lab using X-ray fluorescence (XRF) spectrometry.


This animation explains new research from the University of Plymouth into how three ancient land


 masses collided to form the British Isles [Credit: University of Plymouth]


The samples were also then dissolved in acid in order to conduct a more intensive isotopic analysis, with scientists examining the levels of two elements – strontium and neodymium – to understand the full history of the rocks.
These findings were then compared with previous studies elsewhere in the UK and mainland Europe, with the results showing the clear boundary running from the Exe estuary in the East to Camelford in the west.


“We always knew that around 10,000 years ago you would have been able to walk from England to France,” Dr Dijkstra added. “But our findings show that millions of years before that, the bonds between the two countries would have been even stronger. It explains the immense mineral wealth of South West England, which had previously been something of a mystery, and provides a fascinating new insight into the geological history of the UK.”


Source: University of Plymouth [September 14, 2018]



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Genetics in Sight What can you see at the very edges of your…


Genetics in Sight


What can you see at the very edges of your vision, beyond these beautiful images on your screen? This peripheral vision is the first thing lost by people with retinitis pigmentosa, a genetic disease with no cure that can result in a total blindness. Identifying the genes involved is a step towards improving patients’ prospects, and a new study found that eight families with RP sufferers all shared a particular version of a gene called CLCC1. Usually, this gene produces a ubiquitous protein in cells around the body. But when it’s distorted, eye cells don’t develop quite as they should, as shown by the affected zebrafish eye sections (right) compared to healthy ones (left). Highlighted in red are rod (bottom) and cone (top) cells which are crucial to vision and depleted in RP patients. CLCC1 presents a new marker to diagnose patients, and maybe a path to new potential treatments.


Written by Anthony Lewis



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Cassini’s Final View of Titan’s Northern Lakes and Seas


NASA – Cassini Mission to Saturn patch.


September 14, 2018


During NASA’s Cassini mission’s final distant encounter with Saturn’s giant moon Titan, the spacecraft captured the enigmatic moon’s north polar landscape of lakes and seas, which are filled with liquid methane and ethane.



Image above: During NASA’s Cassini mission’s final distant encounter with Saturn’s giant moon Titan, the spacecraft captured this view of the enigmatic moon’s north polar landscape of lakes and seas, which are filled with liquid methane and ethane. Image Credits: NASA/JPL-Caltech/SSI.


They were captured on Sept. 11, 2017. Four days later, Cassini was deliberately plunged into the atmosphere of Saturn.


Punga Mare (240 miles, or 390 kilometers, across) is seen just above the center of the mosaic, with Ligeia Mare (300 miles, or 500 kilometers, wide) below center and the vast Kraken Mare stretching off 730 miles (1,200 kilometers) to the left of the mosaic. Titan’s numerous smaller lakes can be seen around the seas and scattered around the right side of the mosaic. Among the ongoing mysteries about Titan is how these lakes are formed.


Another mystery at Titan has been the weather. With its dense atmosphere, Titan has a methane cycle much like Earth’s water cycle of evaporation, cloud formation, rainfall, surface runoff into rivers, and collection in lakes and seas. During Titan’s southern summer, Cassini observed cloud activity over the south pole (see PIA06112 and PIA06109).


PIA06112: https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA06112


PIA06109: https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA06109


However, typical of observations taken during northern spring and summer, the view here reveals only a few small clouds. They appear as bright features just below the center of the mosaic, including a few above Ligeia Mare.


“We expected more symmetry between the southern and northern summer,” said Elizabeth (“Zibi”) Turtle of the Johns Hopkins Applied Physics Lab and the Cassini Imaging Science Subsystem (ISS) team that captured the image. “In fact, atmospheric models predicted summer clouds over the northern latitudes several years ago. So, the fact that they still hadn’t appeared before the end of the mission is telling us something interesting about Titan’s methane cycle and weather.”


“Titan is a fascinating place that really teases us with some of its mysteries,” said Turtle.


The images in this mosaic were taken with the ISS narrow-angle camera, using a spectral filter sensitive to wavelengths of near-infrared light centered at 938 nanometers.


The view was obtained at a distance of approximately 87,000 miles (140,000 kilometers) from Titan. Image scale is about 0.5 miles (800 meters) per pixel. The image is an orthographic projection centered on 67.19 degrees north latitude, 212.67 degrees west longitude. An orthographic view is most like the view seen by a distant observer looking through a telescope.


The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA’s Jet Propulsion Laboratory, a division of Caltech in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team consists of scientists from the U.S., England, France and Germany. The imaging operations center and team leader are based at the Space Science Institute in Boulder, Colorado.


For more information about the Cassini Solstice Mission, visit http://ciclops.org, http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov.


Image (mentioned), Text, Credits: NASA/Dwayne Brown/JoAnna Wendel/JPL/Gretchen McCartney.


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Juno Captures Elusive ‘Brown Barge’


NASA – JUNO Mission logo.


September 14, 2018



A long, brown oval known as a “brown barge” in Jupiter’s South Equatorial Belt is captured in this color-enhanced image from NASA’s Juno spacecraft.


Brown barges are cyclonic regions that usually lie within Jupiter’s dark North Equatorial Belt, although they are sometimes found in the similarly dark South Equatorial Belt as well. They can often be difficult to detect visually because their color blends in with the dark surroundings. At other times, as with this image, the dark belt material recedes, creating a lighter-colored background against which the brown barge is more conspicuous. Brown barges usually dissipate after the entire cloud belt undergoes an upheaval and reorganizes itself. Juno is giving us the first glimpses of the detailed structure within such a barge.


This image was taken at 6:26 p.m. PDT on Sept. 6, 2018 (9:26 p.m. EDT) as the spacecraft performed its 15th close flyby of Jupiter. At the time, Juno was 7,425 miles (11,950 kilometers) from the planet’s cloud tops, above a southern latitude of approximately 22 degrees.


Citizen scientist Kevin M. Gill created this image using data from the spacecraft’s JunoCam imager. The image has been rotated 90 degrees to the right from the original image.


JunoCam’s raw images are available at http://www.missionjuno.swri.edu/junocam for the public to peruse and process into image products.


More information about Juno is online at http://www.nasa.gov/juno and http://missionjuno.swri.edu.


NASA’s Jet Propulsion Laboratory manages the Juno mission for the principal investigator, Scott Bolton, of Southwest Research Institute in San Antonio. Juno is part of NASA’s New Frontiers Program, which is managed at NASA’s Marshall Space Flight Center in Huntsville, Alabama, for NASA’s Science Mission Directorate. Lockheed Martin Space Systems, Denver, built the spacecraft. Caltech in Pasadena, California, manages JPL for NASA.


Image, Text, Credits: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill.


Greetings, Orbiter.chArchive link


2018 September 14 Ice Halos at Yellowknife Image Credit &…


2018 September 14


Ice Halos at Yellowknife
Image Credit & Copyright: Stephen Bedingfield


Explanation: You’ve probably seen a circle around the Sun before. More common than rainbows, ice halos, like a 22 degree circular halo for example, can be easy to spot, especially if you can shade your eyes from direct sunlight. Still it’s rare to see such a diverse range of ice halos, including sundogs, tangent, infralateral, and Parry arcs, all found in this snapshot from planet Earth. The picture was quickly taken in the late morning of September 4 from Yellowknife, Northwest Territories, Canada. The beautiful patterns are generated as sunlight (or moonlight) is reflected and refracted in six-sided water ice crystals in Earth’s atmosphere. Of course, atmospheric ice halos in the skies of other worlds are likely to be different.


∞ Source: apod.nasa.gov/apod/ap180914.html


Hubble peers into a galaxy’s dusty haze

This NASA/ESA Hubble Space Telescope image showcases the galaxy NGC 4036, a lenticular galaxy some 70 million light-years away in the constellation of Ursa Major (the Great Bear).











Hubble peers into a galaxy's dusty haze
NGC 4036 [Credit: ESA/Hubble & NASA; Acknowledgment: Judy Schmidt]

This galaxy is known for its irregular lanes of dust, which form a swirling spiral pattern around the center of the galaxy. This core is surrounded by an extended, hazy aura of gas and dust that stretches farther out into space and causes the warm, fuzzy glow that can be seen here.
The center itself is also intriguing; it is something known as a LINER-type (Low-Ionization Nuclear Emission-line Region) galactic nucleus, meaning that it displays particular emission lines within its spectrum. The particularly bright star visible slightly to the right of the galactic center is not within the galaxy itself; it sits between us and NGC 4036, adding a burst of brightness to the scene.


Due to its relative brightness, this galaxy can be seen using an amateur telescope, making it a favorite amongst backyard astronomers and astrophotography aficionados.


Source: NASA [September 10, 2018]




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Artificial intelligence helps track down mysterious cosmic radio bursts

Artificial intelligence is invading many fields, most recently astronomy and the search for intelligent life in the universe, or SETI.











Artificial intelligence helps track down mysterious cosmic radio bursts
Breakthrough Listen researchers used artificial intelligence to search through radio signals recorded from a fast radio
burst, capturing many more than humans could. They are using a similar algorithm to search for new kinds
 of candidate signals from extraterrestrial civilizations [Credit: Breakthrough Listen image]

Researchers at Breakthrough Listen, a SETI project led by the University of California, Berkeley, have now used machine learning to discover 72 new fast radio bursts from a mysterious source some 3 billion light years from Earth.


Fast radio bursts are bright pulses of radio emission mere milliseconds in duration, thought to originate from distant galaxies. The source of these emissions is still unclear, however. Theories range from highly magnetized neutron stars blasted by gas streams from a nearby supermassive black hole, to suggestions that the burst properties are consistent with signatures of technology developed by an advanced civilization.


“This work is exciting not just because it helps us understand the dynamic behavior of fast radio bursts in more detail, but also because of the promise it shows for using machine learning to detect signals missed by classical algorithms,” said Andrew Siemion, director of the Berkeley SETI Research Center and principal investigator for Breakthrough Listen, the initiative to find signs of intelligent life in the universe.


Breakthrough Listen is also applying the successful machine-learning algorithm to find new kinds of signals that could be coming from extraterrestrial civilizations.


While most fast radio bursts are one-offs, the source here, FRB 121102, is unique in emitting repeated bursts. This behavior has drawn the attention of many astronomers hoping to pin down the cause and the extreme physics involved in fast radio bursts.


The AI algorithms dredged up the radio signals from data were recorded over a five-hour period on Aug. 26, 2017, by the Green Bank Telescope in West Virginia. An earlier analysis of the 400 terabytes of data employed standard computer algorithms to identify 21 bursts during that period. All were seen within one hour, suggesting that the source alternates between periods of quiescence and frenzied activity, said Berkeley SETI postdoctoral researcher Vishal Gajjar.


UC Berkeley Ph.D. student Gerry Zhang and collaborators subsequently developed a new, powerful machine-learning algorithm and reanalyzed the 2017 data, finding an additional 72 bursts not detected originally. This brings the total number of detected bursts from FRB 121102 to around 300 since it was discovered in 2012.


“This work is only the beginning of using these powerful methods to find radio transients,” said Zhang. “We hope our success may inspire other serious endeavors in applying machine learning to radio astronomy.”


Zhang’s team used some of the same techniques that internet technology companies use to optimize search results and classify images. They trained an algorithm known as a convolutional neural network to recognize bursts found by the classical search method used by Gajjar and collaborators, and then set it loose on the dataset to find bursts that the classical approach missed.


The results have helped put new constraints on the periodicity of the pulses from FRB 121102, suggesting that the pulses are not received with a regular pattern, at least if the period of that pattern is longer than about 10 milliseconds. Just as the patterns of pulses from pulsars have helped astronomers constrain computer models of the extreme physical conditions in such objects, the new measurements of FRBs will help figure out what powers these enigmatic sources, Siemion said.


“Whether or not FRBs themselves eventually turn out to be signatures of extraterrestrial technology, Breakthrough Listen is helping to push the frontiers of a new and rapidly growing area of our understanding of the Universe around us,” he added.


The new results are described in an article accepted for publication in The Astrophysical Journal and available for download from the Breakthrough Listen website.


Source: University of California – Berkeley [September 10, 2018]



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BUFFALO charges towards the earliest galaxies




BUFFALO’s view on Abell 370



PR Image heic1816b


The last of the Frontier Fields — Abell 370



Comparison between Frontier Fields and BUFFALO



Digitized sky survey image of Abell 370 (ground-based image)




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Zooming onto the galaxy cluster Abell 370



Zooming onto the galaxy cluster Abell 370



Pan across Abell 370



Pan across Abell 370




New Hubble project provides wide-field view of the galaxy cluster Abell 370



The NASA/ESA Hubble Space Telescope has started a new mission to shed light on the evolution of the earliest galaxies in the Universe. The BUFFALO survey will observe six massive galaxy clusters and their surroundings. The first observations show the galaxy cluster Abell 370 and a host of magnified, gravitationally lensed galaxies around it.


Learning about the formation and evolution of the very first galaxies in the Universe is crucial for our understanding of the cosmos. While the NASA/ESA Hubble Space Telescope has already detected some of the most distant galaxies known, their numbers are small, making it hard for astronomers to determine if they represent the Universe at large.


Massive galaxy clusters like Abell 370, which is visible in this new image, can help astronomers find more of these distant objects. The immense masses of galaxy clusters make them act as cosmic magnifying glasses. A cluster’s mass bends and magnifies light from more distant objects behind it, uncovering objects otherwise too faint for even Hubble’s sensitive vision. Using this cosmological trick — known as strong gravitational lensing — Hubble is able to explore some of the earliest and most distant galaxies in the Universe.


Numerous galaxies are lensed by the mass of Abell 370. The most stunning demonstration of gravitational lensing can be seen just below the centre of the cluster. Nicknamed “the Dragon”, this extended feature is made up of a multitude of duplicated images of a spiral galaxy which lies beyond the cluster.


This image of Abell 370 and its surroundings was made as part of the new Beyond Ultra-deep Frontier Fields And Legacy Observations (BUFFALO) survey. This project, led by European astronomers from the Niels Bohr Institute (Denmark) and Durham University (UK), was designed to succeed the successful Frontier Fields project [1]. 101 Hubble orbits — corresponding to 160 hours of precious observation time — have been dedicated to exploring the six Frontier Field galaxy clusters. These additional observations focus on the regions surrounding the galaxy clusters, allowing for a larger field of view.


BUFFALO’s main mission, however, is to investigate how and when the most massive and luminous galaxies in the Universe formed and how early galaxy formation is linked to dark matter assembly. This will allow astronomers to determine how rapidly galaxies formed in the first 800 million years after the Big Bang — paving the way for observations with the upcoming NASA/ESA/CSA James Webb Space Telescope.


Driven by the Frontier Fields observations, BUFFALO will be able to detect the most distant galaxies approximately ten times more efficiently than its progenitor programme. The BUFFALO survey will also take advantage of other space telescopes which have already observed the regions around the clusters. These datasets will be included in the search for the first galaxies.


The extended fields of view will also allow better 3-dimensional mapping of the mass distribution — of both ordinary and dark matter — within each galaxy cluster. These maps help astronomers learn more about the evolution of the lensing galaxy clusters and about the nature of dark matter.



Notes


[1] Frontier Fields was a Hubble programme that ran from 2013 to 2017. Hubble spent 630 hours of observation time probing six notable galaxy clusters, all of which showed effects of strong gravitational lensing.




More information



The Hubble Space Telescope is a project of international cooperation between ESA and NASA.



Image credit: NASA, ESA, A. Koekemoer, M. Jauzac, C. Steinhardt, and the BUFFALO team




Links






Contacts


Charles Steinhardt

Niels Bohr Institute

Copenhagen, Denmark

Tel: +45 35 33 50 10



Mathilde Jauzac

Durham University

Durham, UK

Tel: +44 7445218614



Mathias Jäger

ESA/Hubble, Public Information Officer

Garching, Germany

Tel: +49 176 62397500











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Early Christian Crosses and Stones, Whithorn Museum and Priory, Whithorn, Newton Stewart,...









Early Christian Crosses and Stones, Whithorn Museum and Priory, Whithorn, Newton Stewart, Scotland, 9.9.18.


These are some of the oldest Christian relics in Scotland. The earliest stone dates from 410CE; shortly after the end of Roman occupation of Britain. The stones feature designs and motifs drawn from different cultures and sources.


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