четверг, 25 апреля 2019 г.

Moulding the Folding If I handed you a napkin beautifully…


Moulding the Folding


If I handed you a napkin beautifully folded into the shape of a swan, would you know how it was made? That’s the challenge facing researchers trying to understand how the infinitely complex folds of the human brain take shape during development. Various competing theories explain their origin. Do outer cells pull in different directions, or do uneven growth speeds cause the bulges? Errors in the folding process can lead to serious illnesses, so understanding the mechanism could have real impacts. To investigate, researchers looked to the mouse cerebellum – a small part of the brain, and a simpler prospect to interrogate. They found that during the first stages of folding, cells in the outer layer (pictured) grow uniformly and faster than inner cells, and with fluid-like flexibility. By revealing this and a previously unknown combination of forces, such as surrounding tensions restricting growth, the researchers are helping unfold the mystery.


Written by Anthony Lewis



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The Giant In Our Backyard


Artist impression of the heart of galaxy NGC 1068, which harbors an actively feeding supermassive black hole.

Credit: NRAO/AUI/NSF; D. Berry / Skyworks




The center of our Milky Way Galaxy is only clearly visible to radio telescopes. The supermassive black hole in its core is glaring in radio waves, surrounded by the smoke rings of supernova remnants and the arcs of material caught in the core’s strong magnetic fields. This gigantic image was pieced together by multiple observations taken by the Very Large Array (VLA). Credit: NRAO/AUI/NSF. Hi-Res File



Top left: Simulation of Sgr A* at 86 GHz. Top right: Simulation with added effects of scattering. Bottom right: Scattered image from the observations, this is how we see Sgr A* on the sky. Bottom left: The unscattered image, after removing the effects of scattering along our line of sight, this is how Sgr A* really looks like. Credit: S. Issaoun, M. Mościbrodzka, Radboud University/ M. D. Johnson, CfA. Hi-Res File



This infographic details the locations of the participating telescopes of the Event Horizon Telescope (EHT) and the Global mm-VLBI Array (GMVA). Their goal is to image, for the very first time, the shadow of the event horizon of the supermassive black hole at the center of the Milky Way, as well as to study the properties of the accretion and outflow around the Galactic Centre. Credit: ESO/O. Furtak. Hi-Res File




Synopsis: Recently, a collection of radio observatories combined to form the GMVA, a powerful tool that probed the region near our galaxy’s supermassive black hole. This produced curious images of this region, glowing brightly in millimeter-wavelength radio light. These observations, which involved three U.S. radio telescopes – VLA, VLBA, and GBT – are an important step toward observing the event horizon of a supermassive black hole. Here is this story of this quest so far:


There is a giant in our backyard. We know it’s there, but no one has ever seen it. It’s a supermassive black hole , and it lurks in the center of our galaxy.


In 1931, engineer Karl Jansky first observed a strong cosmic radio signal emanating from the constellation Sagittarius, which lies in the direction to the center of our galaxy. Jansky assumed that the radio signals originated from the center of our galaxy, but he had no idea what that source could be and his telescope was incapable pinpointing the location of the exact source. That happened in 1974, when Bruce Balick and Robert Brown used three radio dishes at Green Bank Observatory and a fourth smaller dish about 35 km away to form a vastly more precise radio telescope called an interferometer.


An interferometer is a way to use multiple radio telescopes or antennas as a single virtual telescope. When two antenna dishes are pointed at the same object in the sky they receive the same signal, but the signals are out of sync because it takes a bit longer to reach one antenna than the other. The time difference depends upon the direction of the antennas and their spacing apart from each other. By correlating the two signals you can determine the location of the source very precisely. With the Green Bank Interferometer, Balick and Brown confirmed the radio source as a small region near the galactic center. Brown later named the source Sagittarius A*, or Sgr A* for short.


The Green Bank Interferometer was a precursor to NRAO’s Very Large Array (VLA). The VLA has an array of 28 antennas capable of both widely separated and closely spaced configurations, making it the perfect tool for studying Sgr A*. In 1983, a team led by Ron Ekers used the VLA to make the first radio image of the Galactic Center, which revealed a mini-spiral of hot gas. Later observations showed not only the spiral of gas, but also a distinct and bright radio source at the exact center of the Milky Way.


By this time it was strongly suspected that this radio source was a massive black hole. From 1982 to 1998, Don Backer and Dick Sramek at the VLA measured the position of Sgr A* and found that it had almost no apparent motion. This meant it must be extremely massive since the gravitational tugs of nearby stars weren’t moving it about. They estimated it must have a mass at least two million times larger than the Sun. Long-term observations of stars orbiting the Galactic Center


have found Sgr A* to be about 3.6 million solar masses, and precise radio imaging has confirmed it can be no larger than the orbit of Mercury. We now know it is indeed a supermassive black hole.


Knowing a black hole is there isn’t the same as seeing it directly. Astronomers have long dreamed of directly observing a black hole, and perhaps even glimpsing its event horizon . Sagittarius A* is the closest supermassive black hole to Earth, so there have been various efforts to observe it directly. But there are two big challenges to be overcome. The first is that the center of our galaxy is surrounded by dense gas and dust. Almost all the visible light from the region is obscured, so we can’t observe the black hole with an optical telescope. Fortunately, the gas and dust are relatively transparent to radio light, so radio telescopes can see to the heart of our galaxy. But this leads to the second major challenge: resolution.


Although the Sgr A* black hole is massive, it is only about the size of a large star. According to Einstein’s theory of general relativity, a black hole of 3.6 million solar masses would have an event horizon only 15 times wider than the Sun. Since the Galactic Center is about 26,000 light years away from Earth, the black hole appears very small in the sky, about the same apparent size as a baseball sitting on the surface of the Moon. To see a radio object that small, you’d need a telescope the size of Earth itself.


Obviously, we can’t build a radio telescope the size of our planet, but with radio interferometry we can build a virtual Earth-sized telescope. NRAO observatories are currently working with two projects trying to observe a black hole, the Event Horizon Telescope (EHT) and the Global mm-VLBI Array (GMVA). The Atacama Large Millimeter/submillimeter Array (ALMA) is participating in both projects, while the Green Bank Telescope (GBT) and the Very Long Baseline Array (VLBA)


are part of GMVA. Just like the Very Large Array, these projects combine signals from multiple antennas. Since the antennas are located all over the world, this virtual telescope is about the size of the Earth. But unlike the VLA antennas, they all have different sizes and sensitivities. This diversity of antennas makes it more difficult to combine signals, but it also gives the projects a big advantage.


In the VLA, for example, all the antennas of the array are identical. Each antenna contributes equally, and the sensitivity of the array depends upon the size of a single antenna. But when telescopes, or antennas of different sizes, are combined, the sensitivity of the larger antennas helps boost the sensitivity of the smaller ones. The Green Bank Telescope, for example, has a diameter of 100 meters. When combined with smaller telescopes in a large interferometer, the total sensitivity depends upon the average size of all the antennas. This makes the ALMA array — connected to the EHT and the GMVA — and the GBT — linked to the GMVA — much more sensitive to signals from the Milky Way’s black hole, and we’ll need all the sensitivity we can get to capture the image of a black hole.


In January of 2019, GMVA captured an image of Sagittarius A* at 3mm wavelengths, but the scattering of 3mm light by the plasma between us and Sgr A* made it impossible to see the shadow of its event horizon. The first clear image of a black hole was announced by the Event Horizon Telescope in April 2019. It was an image of the black hole in the galaxy M87. While M87 is more than 2,000 times more distant than the black hole in the center of our galaxy, its black hole is also 1,500 times more massive. It’s a very active black hole, and not obscured by the gas and dust in our galaxy, making it easier to observe. Observing our smaller, quieter black hole is a bigger challenge. But by working with observatories all over the world, ALMA and the GBT will soon catch the first clear glimpse of the giant in our backyard.

Contact:

Brian Koberlein
bkoberle@nrao.edu




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Some myths die hard

Ancient DNA tells us that the Bronze Age wasn’t kind to the indigenous populations of Central Asia. It seems to have wiped them out totally. Indeed, Central Asia might well be the only major world region in which native hunter-gatherers failed to make a perceptible impact on the genetics of any extant populations.
Before the Neolithic transition, much of Central Asia was home to hunter-gatherers closely related to those of nearby western Siberia. During the Neolithic, agriculturalists and pastoralists from the Near East gradually moved into the more arable parts of southern and eastern Central Asia, eventually giving rise to the Bactria Margiana Archaeological Complex, or BMAC, and other similar communities.
It’s not clear what their relationship was like with the native hunter-gatherers in these areas. But they did mix with them in varying degrees. This is obvious because genome-wide genetic ancestry characteristic of the Botai people, who hunted and eventually domesticated horses on the Kazakh steppe during the 4th millennium BCE, and were probably the archetypal Central Asians for their time, is found at significant levels in a number of later samples from Central Asian farmer and pastoralist sites, such as Dali, Gonur Tepe and Sarazm.
Thus, even though the Neolithic transition did have a big impact on Central Asia, and clearly led to large scale population replacements in some parts of the region, this was just the beginning of these population shifts. Moreover, in some cases the expanding farmer and pastoralist populations seem to have acquired significant indigenous Central Asian ancestry and spread it with them.
The precise geographic extent of the relatively unique Botai-related ancestry in prehistoric Eurasia is still something of a mystery. But to give you a general picture of where it was found from around 6,000 BCE to 2,000 BCE, here’s a map with info about samples with significant levels of this type of ancestry from a wide range of sites in space and time.



Going by this map, I’d say it’s safe to infer that the Botai-related ancestry was a major feature of practically all forager populations living between the Caspian Sea and the Altai Mountains. It was also present in the early pastoralist population associated with the Steppe Maykop archeological culture of Eastern Europe, so it may have already been in Europe as early as 3,800 BCE, because that’s when the Steppe Maykop culture first appeared.
It’s an interesting question where the ancestors of the Steppe Maykop herders came from. I once simply assumed that they were closely related to the Maykop people who lived in the Caucasus Mountains. But it’s now clear that the populations associated with these two similar cultures were starkly different, with the Maykop people being basically of Near Eastern origin and lacking any discernible Botai-like ancestry. My guess for now is that the Steppe Maykop herders were in large part the descendants of the Kelteminar culture population from just east of the Caspian Sea, but we’ll see about that when more ancient DNA comes in.
The other great mystery is what eventually happened to the Steppe Maykop people. Around 3,000 BCE their culture vanished from the archeological record, and, around the same time, their particular genetic signature disappeared from the steppe ancient DNA record. Where did they go? Did they migrate back east?
I don’t know, but at about that time other Eastern European steppe herders, those associated with the Yamnaya and Corded Ware archeological cultures, began to stir and migrate in big numbers in basically all directions, including into Steppe Maykop territory. Indeed, unlike the Steppe Maykop population, these groups weren’t closely related to any contemporaneous or earlier Central Asians. But they ended up moving into Central Asia, and in a big way too.
Their impact all the way from the Ural Mountains to what are now China and India was profound. For instance, not only did they end up totally replacing the Botai people, but also their horses. For more details on this topic check out the Youtube clip here. I have a strong suspicion that the same sort of thing happened to the aforementioned Steppe Maykop people. In other words, they may have been forced out from the Eastern European steppe, and perhaps sought shelter in the Caucasus Mountains?
Admittedly, I’m not offering anything new here. I just wanted to emphasize a few key points, because I’m still seeing some confusion online about the population history of Central Asia, and especially how it relates to the population history of Europe, and also the Proto-Indo-European homeland question. Make no mistake, thanks to the ancient DNA already available from Central Asia, we can confidently infer the following:



— the chance that the ancient European populations associated with the Yamnaya, Corded Ware and other closely related archeological cultures formed as a result of migrations from Central Asia is zero
— the chance that the Proto-Indo-European homeland was located in Central Asia is zero
— the chance that present-day Europeans, by and large, derive from any ancient Central Asian populations is zero



See also…
Central Asia as the PIE urheimat? Forget it
The Steppe Maykop enigma
Late PIE ground zero now obvious; location of PIE homeland still uncertain, but…

Source


The first Chinese on the Moon in ten years?


CLEP — China Lunar Exploration Program logo.


April 25, 2019


Beijing aims to build a scientific research station in the regions of the South Pole of the Moon in about ten years.



Taikonauts on the Moon in 2029? (Photo-montage, illustation) Image Credits: NASA/Apollo 11

The announcement comes as China has achieved in January a world first: the moon landing of a probe on the far side of the moon.


China will send a first manned mission to the moon «in a decade,» said China’s top space program chief, while the United States aims to return to lunar soil by 2024.


«China aims to build a scientific research station in the regions of the South Pole of the Moon and to carry out manned lunar missions in a decade,» said the director of the National Administration of Space, Zhang Kejian, quoted by the news agency China News.


Beijing has for many years evoked an inhabited mission on the Moon but no precise date has ever been provided, experts usually rely on a date after 2025.


After a successful lunar landing


Mr. Zhang’s announcement comes as the country has achieved a world premiere at the start of the year: the moon landing of a probe on the far side of the moon. The communist regime relies heavily on its space programs to glorify the country’s technological progress in recent decades, in a race with the West that evokes Soviet-American space rivalry during the Cold War.



Animation above: Yutu-2 rover leave Chang’e-4 lander and start exploring the Von Karman Crater. Animation Credits: CNSA / CLEP / Orbiter.ch Aerospace / Roland Berga.


The words of the Chinese leader come less than a month after Washington announced a return of American astronauts to the moon in 2024, instead of 2028 as originally planned. The United States was the first and only one to send men to the moon between 1969 and 1972.


Zhang said Beijing plans to send its first probe to Mars next year. In addition to the probe currently on the far side of the moon, China also plans to send at the end of this year another machine responsible for bringing lunar samples back to Earth, he said.



Yutu-2 Lunar Rover. Image Credits: CNSA / CLEP

Witnessing the political dimension of these missions, Zhang said that lunar samples would be kept in Shaoshan (center), the hometown of Mao Tse-tung, the founder of the communist regime. China sent a first man into space in 2003 and achieved his first landing of a spacecraft 10 years later.


Related articles & links:


China’s Chang’e-4 Probe Wakes Up after First Lunar Night
https://orbiterchspacenews.blogspot.com/2019/02/chinas-change-4-probe-wakes-up-after.html


China’s Yutu-2 rover Enters Standby Mode for ‘Noon Nap’ as Chang’e 4 Tests Continue
https://orbiterchspacenews.blogspot.com/2019/01/chinas-yutu-2-rover-enters-standby-mode.html


Sending American Astronauts to Moon in 2024: NASA Accepts Challenge
https://orbiterchspacenews.blogspot.com/2019/04/sending-american-astronauts-to-moon-in.html


For more information about China Aerospace Science and Technology Corporation (CASC), visit: http://english.spacechina.com/n16421/index.html


For more information about China National Space Administration (CNSA), visit: http://www.cnsa.gov.cn/


Images (mentioned), Animation (mentioned), Text, Credits: AFP/CNSA/CLEP/Orbiter.ch Aerospace/Roland Berga.


Greetings, Orbiter.chArchive link


Butterflies swarm Lebanon’s meadows in numbers unseen for 100 years

A vast number of migrating butterflies have swarmed across Lebanon this year after heavy winter rain in the Middle East led to an exceptional spring for wild flowers.











Butterflies swarm Lebanon's meadows in numbers unseen for 100 years
A painted lady butterfly sits on a flower in a field at the village of Mrouj, Lebanon April 13, 2019
[Credit: Mohamed Azakir/Reuters]

“The last time this migration happened in this way was back in 1917,” said Magda Bou Dagher Kharrat, a professor in plant genetics at Lebanon’s St Joseph University.


The sheer number of Vanessa Cardui butterflies traveling from Africa to northern Europe caused admiring bewilderment, as millions crossed mountains, fields, villages and cities.


“They did not only pass through wild areas, forests and nature… so even the people who don’t usually go out to nature witnessed this migration,” said Bou Dagher Kharrat.


“What happened this year should be noted down for history.”


The butterflies’ distinctive black, white and russet wings have earned them the common name of “painted lady” and they could be seen in the northern villages of Mrouj and Zaarour flitting across large meadows of wild flowers.











Butterflies swarm Lebanon's meadows in numbers unseen for 100 years
A painted lady butterfly sits on a flower in a field at the village of Mrouj, Lebanon April 13, 2019
[Credit: Mohamed Azakir/Reuters]

“It was something really beautiful. People were stopping on the road to watch them… We have never seen anything like it before,” said Rony Kharrat in Zaarour.


But for some villagers the influx brought back reminders of a locust infestation that fell upon Lebanon during its Great Famine of 1915-18, in which thousands died and many others emigrated.


Nassib al-Alam, an elderly farmer who has plowed his fields for the past 60 years, said at first some people had thought the locusts were back.


“Everywhere is still green, these (butterflies) are just passing by,” he said, with snowcapped mountains behind him, another rare sight in mid-spring when most of the snow has usually melted. “They are beautiful.”


Author: Imad Creidi | Source: Reuters [April 22, 2019]



TANN



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Mystery of the Universe’s Expansion Rate Widens With New Hubble Data



This is a ground-based telescope’s view of the Large Magellanic Cloud, a satellite galaxy of our Milky Way. The inset image, taken by the Hubble Space Telescope, reveals one of many star clusters scattered throughout the dwarf galaxy. The cluster members include a special class of pulsating star called a Cepheid variable, which brightens and dims at a predictable rate that corresponds to its intrinsic brightness. Once astronomers determine that value, they can measure the light from these stars to calculate an accurate distance to the galaxy. When the new Hubble observations are correlated with an independent distance measurement technique to the Large Magellanic Cloud (using straightforward trigonometry), the researchers were able to strengthen the foundation of the so-called «cosmic distance ladder.» This «fine-tuning» has significantly improved the accuracy of the rate at which the universe is expanding, called the Hubble constant. Credits: NASA, ESA, A. Riess (STScI/JHU) and Palomar Digitized Sky Survey. Hi-res image



Astronomers using NASA’s Hubble Space Telescope say they have crossed an important threshold in revealing a discrepancy between the two key techniques for measuring the universe’s expansion rate. The recent study strengthens the case that new theories may be needed to explain the forces that have shaped the cosmos.


A brief recap: The universe is getting bigger every second. The space between galaxies is stretching, like dough rising in the oven. But how fast is the universe expanding? As Hubble and other telescopes seek to answer this question, they have run into an intriguing difference between what scientists predict and what they observe.


Hubble measurements suggest a faster expansion rate in the modern universe than expected, based on how the universe appeared more than 13 billion years ago. These measurements of the early universe come from the European Space Agency’s Planck satellite. This discrepancy has been identified in scientific papers over the last several years, but it has been unclear whether differences in measurement techniques are to blame, or whether the difference could result from unlucky measurements.


The latest Hubble data lower the possibility that the discrepancy is only a fluke to 1 in 100,000. This is a significant gain from an earlier estimate, less than a year ago, of a chance of 1 in 3,000.


These most precise Hubble measurements to date bolster the idea that new physics may be needed to explain the mismatch.


«The Hubble tension between the early and late universe may be the most exciting development in cosmology in decades,» said lead researcher and Nobel laureate Adam Riess of the Space Telescope Science Institute (STScI) and Johns Hopkins University, in Baltimore, Maryland. «This mismatch has been growing and has now reached a point that is really impossible to dismiss as a fluke. This disparity could not plausibly occur just by chance.»

Tightening the bolts on the ‘cosmic distance ladder


Scientists use a «cosmic distance ladder» to determine how far away things are in the universe. This method depends on making accurate measurements of distances to nearby galaxies and then moving to galaxies farther and farther away, using their stars as milepost markers. Astronomers use these values, along with other measurements of the galaxies’ light that reddens as it passes through a stretching universe, to calculate how fast the cosmos expands with time, a value known as the Hubble constant. Riess and his SH0ES (Supernovae H0 for the Equation of State) team have been on a quest since 2005 to refine those distance measurements with Hubble and fine-tune the Hubble constant.


In this new study, astronomers used Hubble to observe 70 pulsating stars called Cepheid variables in the Large Magellanic Cloud. The observations helped the astronomers «rebuild» the distance ladder by improving the comparison between those Cepheids and their more distant cousins in the galactic hosts of supernovas. Riess’s team reduced the uncertainty in their Hubble constant value to 1.9% from an earlier estimate of 2.2%.


As the team’s measurements have become more precise, their calculation of the Hubble constant has remained at odds with the expected value derived from observations of the early universe’s expansion. Those measurements were made by Planck, which maps the cosmic microwave background, a relic afterglow from 380,000 years after the big bang.


The measurements have been thoroughly vetted, so astronomers cannot currently dismiss the gap between the two results as due to an error in any single measurement or method. Both values have been tested multiple ways.


«This is not just two experiments disagreeing,» Riess explained. «We are measuring something fundamentally different. One is a measurement of how fast the universe is expanding today, as we see it. The other is a prediction based on the physics of the early universe and on measurements of how fast it ought to be expanding. If these values don’t agree, there becomes a very strong likelihood that we’re missing something in the cosmological model that connects the two eras.»


How the new study was done


Astronomers have been using Cepheid variables as cosmic yardsticks to gauge nearby intergalactic distances for more than a century. But trying to harvest a bunch of these stars was so time-consuming as to be nearly unachievable. So, the team employed a clever new method, called DASH (Drift And Shift), using Hubble as a «point-and-shoot» camera to snap quick images of the extremely bright pulsating stars, which eliminates the time-consuming need for precise pointing.




This illustration shows the three basic steps astronomers use to calculate how fast the universe expands over time, a value called the Hubble constant. All the steps involve building a strong «cosmic distance ladder,» by starting with measuring accurate distances to nearby galaxies and then moving to galaxies farther and farther away. This «ladder» is a series of measurements of different kinds of astronomical objects with an intrinsic brightness that researchers can use to calculate distances. Among the most reliable for shorter distances are Cepheid variables, stars that pulsate at predictable rates that indicate their intrinsic brightness. Astronomers recently used the Hubble Space Telescope to observe 70 Cepheid variables in the nearby Large Magellanic Cloud to make the most precise distance measurement to that galaxy. Astronomers compare the measurements of nearby Cepheids to those in galaxies farther away that also include another cosmic yardstick, exploding stars called Type Ia supernovas. These supernovas are much brighter than Cepheid variables. Astronomers use them as «milepost markers» to gauge the distance from Earth to far-flung galaxies. Each of these markers build upon the previous step in the «ladder.» By extending the ladder using different kinds of reliable milepost markers, astronomers can reach very large distances in the universe. Astronomers compare these distance values to measurements of an entire galaxy’s light, which increasingly reddens with distance, due to the uniform expansion of space. Astronomers can then calculate how fast the cosmos is expanding: the Hubble constant. Credits: NASA, ESA and A. Feild (STScI). Hi-res image


Download Hubble Constant Infographic as PDF


«When Hubble uses precise pointing by locking onto guide stars, it can only observe one Cepheid per each 90-minute Hubble orbit around Earth. So, it would be very costly for the telescope to observe each Cepheid,» explained team member Stefano Casertano, also of STScI and Johns Hopkins. «Instead, we searched for groups of Cepheids close enough to each other that we could move between them without recalibrating the telescope pointing. These Cepheids are so bright, we only need to observe them for two seconds. This technique is allowing us to observe a dozen Cepheids for the duration of one orbit. So, we stay on gyroscope control and keep ‘DASHing’ around very fast.»


The Hubble astronomers then combined their result with another set of observations, made by the Araucaria Project, a collaboration between astronomers from institutions in Chile, the U.S., and Europe. This group made distance measurements to the Large Magellanic Cloud by observing the dimming of light as one star passes in front of its partner in eclipsing binary-star systems.


The combined measurements helped the SH0ES Team refine the Cepheids’ true brightness. With this more accurate result, the team could then «tighten the bolts» of the rest of the distance ladder that extends deeper into space.


The new estimate of the Hubble constant is 74 kilometers (46 miles) per second per megaparsec. This means that for every 3.3 million light-years farther away a galaxy is from us, it appears to be moving 74 kilometers (46 miles) per second faster, as a result of the expansion of the universe. The number indicates that the universe is expanding at a 9% faster rate than the prediction of 67 kilometers (41.6 miles) per second per megaparsec, which comes from Planck’s observations of the early universe, coupled with our present understanding of the universe.

So, what could explain this discrepancy?


One explanation for the mismatch involves an unexpected appearance of dark energy in the young universe, which is thought to now comprise 70% of the universe’s contents. Proposed by astronomers at Johns Hopkins, the theory is dubbed «early dark energy,» and suggests that the universe evolved like a three-act play.


Astronomers have already hypothesized that dark energy existed during the first seconds after the big bang and pushed matter throughout space, starting the initial expansion. Dark energy may also be the reason for the universe’s accelerated expansion today. The new theory suggests that there was a third dark-energy episode not long after the big bang, which expanded the universe faster than astronomers had predicted. The existence of this «early dark energy» could account for the tension between the two Hubble constant values, Riess said.


Another idea is that the universe contains a new subatomic particle that travels close to the speed of light. Such speedy particles are collectively called «dark radiation» and include previously known particles like neutrinos, which are created in nuclear reactions and radioactive decays.


Yet another attractive possibility is that dark matter (an invisible form of matter not made up of protons, neutrons, and electrons) interacts more strongly with normal matter or radiation than previously assumed.

But the true explanation is still a mystery.


Riess doesn’t have an answer to this vexing problem, but his team will continue to use Hubble to reduce the uncertainties in the Hubble constant. Their goal is to decrease the uncertainty to 1%, which should help astronomers identify the cause of the discrepancy.

The team’s results have been accepted for publication in The Astrophysical Journal.


The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.

Donna Weaver / Ray Villard
Space Telescope Science Institute, Baltimore, Md.
410-338-4493 / 410-338-4514
dweaver@stsci.edu / villard@stsci.edu


Adam Riess
Space Telescope Science Institute, Baltimore, Md.
and Johns Hopkins University, Baltimore, Md.
410-338-6707
ariess@stsci.edu


Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, Md.
301-286-1940
claire.andreoli@nasa.gov


Editor: Rob Garner


Source: NASA/Hubble



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Eclogitic diamonds formed from oceanic crust…


Eclogitic diamonds formed from oceanic crust http://www.geologypage.com/2019/04/eclogitic-diamonds-formed-from-oceanic-crust.html


2019 April 25 Pan-STARRS Across the Lagoon Image Data Credit:…


2019 April 25


Pan-STARRS Across the Lagoon
Image Data Credit: Pan-STARRS, Eric Coles, Martin PughProcessing: Eric Coles


Explanation: Ridges of glowing interstellar gas and dark dust clouds inhabit the turbulent, cosmic depths of the Lagoon Nebula. Also known as M8, the bright star forming region is about 5,000 light-years distant. But it still makes for a popular stop on telescopic tours of the constellation Sagittarius, toward the center of our Milky Way Galaxy. Dominated by the telltale red emission of ionized hydrogen atoms recombining with stripped electrons, this stunning view of the Lagoon is over 100 light-years across. At its center, the bright, compact, hourglass shape is gas ionized and sculpted by energetic radiation and extreme stellar winds from a massive young star. In fact, the many bright stars of open cluster NGC 6530 drift within the nebula, just formed in the Lagoon several million years ago. Broadband image data from Pan-STARRS (Panoramic Survey Telescope & Rapid Response System) was combined with narrowband data from amateur telescopes to create this wide and deep portrait of the Lagoon Nebula.


∞ Source: apod.nasa.gov/apod/ap190425.html


Space Station Science Highlights: Week of April 15, 2019


ISS — Expedition 59 Mission patch.


April 24, 2019


Astronauts aboard the International Space Station received a Cygnus commercial resupply ship from Northrop Grumman last week that brought additional science experiments to the orbiting lab. More science arrives in the next few weeks aboard a SpaceX Dragon resupply ship.


Here are details on some of the scientific investigations the Expedition 59 crew members conducted the week of April 15:


Measuring muscle changes in space



Image above: NASA astronaut Anne McClain performs a session for Time Perception in Microgravity, which investigates how crew members aboard the space station perceive time. Astronauts evaluate or reproduce the length of time they see a blue square in the center of the head-mounted display and scientists compare the results with pre- and post-flight baselines. Image Credit: NASA.


The crew collected blood samples and performed ultrasound scans and measurements for the Myotones investigation, which observes the biochemical properties of muscles, such as tone, stiffness, and elasticity, during long-term exposure to spaceflight. Results from this investigation may provide insight into principles of human resting muscle tone and lead to the development of new treatments for rehabilitation on future space missions and on Earth.


Examining how spaceflight affects antibody production


Rodent Research-12 (RR12) examines the effects of spaceflight on the function of antibody production and immune memory. Scientists know that spaceflight has a dramatic influence on immune response. This research looks at the effect following an actual challenge to the body’s immune system. Using a mouse model makes this possible, since the mouse immune system closely parallels that of humans. Last week, the crew set up the habitat and transferred the mice into it for the investigation.



Animation above: NASA astronaut Anne McClain works on the Electrostatic Levitation Furnace (ELF), an experimental facility that can measure thermophysical properties of high temperature melts and achieve solidification from deeply undercooled melts. Animation Credit: NASA.


Measuring perception of time and space


The accurate perception of objects in the environment is a prerequisite for spatial orientation and reliable performance of motor tasks. Motion perception, sound localization, speech, and fine motor coordination in microgravity also depend on time perception. The Time Perception study quantifies subjective changes in a person’s perception of time during and after long-duration exposure to microgravity. The crew used a head-mounted Oculus Rift display, headphones, finger trackball, and laptop computer to perform sessions for this investigation. A program on the laptop creates visual and audio stimuli and measures the subject’s response to spatial and time perception.


A new habitat for mice in space


The crew prepared the JAXA Mouse Habitat Unit for the upcoming JAXA Mouse Mission. That mission analyzes changes in gene expression patterns in several organs and the effects on germ cell development in mice exposed to the space environment for more than 30 days. The Mouse Mission also serves as verification of the Habitat Unit, designed to house mice to and from the space station for scientific investigations. Results could provide fundamental information about how prolonged exposure to space affects humans.



Image above: Canadian Space Agency astronaut David Saint Jacques conducts a session of ISS HAM or Amateur Radio on the International Space Station. This program gives students around the world the experience of talking directly with crew members on the space station, inspiring them to pursue careers in science, technology, engineering and math, and engaging them with radio science technology through amateur radio. Image Credit: NASA.


Other investigations on which the crew performed work:


— The Combustion Integrated Rack (CIR) includes an optics bench, combustion chamber, fuel and oxidizer control, and five different cameras for performing combustion investigations in microgravity: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=317


— The SUBSA investigation crystallizes melts in microgravity to improve understanding of solidification phenomena and crystal production: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=308


— The ISS Experience, a virtual reality film, documents daily life aboard the space station to educate a variety of audiences about life aboard the orbiting lab and science conducted there: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7877


— Airway Monitoring analyzes exhaled air to study airway inflammation in crew members and help maintain crew well-being on future missions: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1067


— Lighting Effects studies the effects on the circadian rhythms, sleep, and cognitive performance of crew members when fluorescent light bulbs on the space station are replaced with solid-state light-emitting diodes (LEDs): https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=2013


— Food Acceptability examines changes in the appeal of food aboard the space station during long-duration missions: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7562


— Standard Measures captures a consistent and simple set of measures from crew members throughout the ISS Program in order to characterize adaptive responses to and risks of living in space: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7711



Space to Ground: Marathon Mission: 04/19/2019

Related links:


Expedition 59: https://www.nasa.gov/mission_pages/station/expeditions/expedition59/index.html


Myotones: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7573


Rodent Research-12 (RR12): https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7868


Time Perception: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7504


Mouse Habitat Unit: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=1537


Spot the Station: https://spotthestation.nasa.gov/


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


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


Images (mentioned), Animation (mentioned), Video (NASA), Text, Credits: NASA/Michael Johnson/Jorge Sotomayor, Lead Increment Scientist Expeditions 59/60.


Best regards, Orbiter.chArchive link


Minerals in mountain rivers tell the story of landslide activity…


Minerals in mountain rivers tell the story of landslide activity upstream http://www.geologypage.com/2019/04/minerals-in-mountain-rivers-tell-the-story-of-landslide-activity-upstream.html


Uncovering Polynya : Research unravels 43-year-old mystery in…


Uncovering Polynya : Research unravels 43-year-old mystery in deep Antarctica http://www.geologypage.com/2019/04/uncovering-polynya-research-unravels-43-year-old-mystery-in-deep-antarctica.html


Rewriting the textbook on fossil fuels…


Rewriting the textbook on fossil fuels http://www.geologypage.com/2019/04/rewriting-the-textbook-on-fossil-fuels.html


NASA’s InSight detects first likely ‘quake’ on Mars…


NASA’s InSight detects first likely ‘quake’ on Mars http://www.geologypage.com/2019/04/nasas-insight-detects-first-likely-quake-on-mars.html


Meet Callichimaera perplexa, the platypus of crabs…


Meet Callichimaera perplexa, the platypus of crabs http://www.geologypage.com/2019/04/meet-callichimaera-perplexa-the-platypus-of-crabs.html


Salish seafloor mapping identifies earthquake and tsunami risks…


Salish seafloor mapping identifies earthquake and tsunami risks http://www.geologypage.com/2019/04/salish-seafloor-mapping-identifies-earthquake-and-tsunami-risks.html


Landslides in Mars’ Cerberus Fossae


NASA — Mars Reconnaissance Orbiter (MRO) patch.


April 24, 2019



Cerberus Fossae is a steep-sided set of troughs cutting volcanic plains to the east of Elysium Mons. Steep slopes on Mars have active landslides (also called «mass wasting»), and here we see evidence for two types of activity.


First, the light bluish boulders on the slope appear to originate at a layer of bedrock (also light blue) near the top of the section. Second, the dark thin lines are recurring slope lineae, probably also due to mass wasting, but composed of finer-grained materials.


This image was captured by the HiRISE camera on the Mars Reconnaissance Orbiter.


Mars Reconnaissance Orbiter (MRO): http://www.nasa.gov/mission_pages/MRO/main/index.html


Image, Text, Credits: NASA/Yvette Smith/JPL-Caltech/University of Arizona.


Greetings, Orbiter.chArchive link


NASA, FEMA, International Partners Plan Asteroid Impact Exercise


NASA logo.


April 24, 2019


While headlines routinely report on “close shaves” and “near-misses” when near-Earth objects (NEOs) such as asteroids or comets pass relatively close to Earth, the real work of preparing for the possibility of a NEO impact with Earth goes on mostly out of the public eye.



Image above: The Manicouagan impact crater in Quebec, Canada, is one of our many reminders that asteroids have impacted Earth. Although large impacts are rare, it’s important to be prepared. That’s why NASA, other US agencies, and international partners gather periodically to simulate impact scenarios and discuss the best course of action for disaster mitigation. Image Credits: International Space Station.


For more than 20 years, NASA and its international partners have been scanning the skies for NEOs, which are asteroids and comets that orbit the Sun and come within 30 million miles (50 million kilometers) of Earth’s orbit. International groups, such as NASA’s Planetary Defense Coordination Office (PDCO), the European Space Agency’s Space Situational Awareness-NEO Segment, and the International Asteroid Warning Network (IAWN) have made better communication of the hazards posed by NEOs a top priority.


In the spirit of better communication, next week at the 2019 Planetary Defense Conference, NASA’s PDCO and other U.S. agencies and space science institutions, along with international partners, will participate in a “tabletop exercise” that will play out a realistic—but fictional—scenario for an asteroid on an impact trajectory with Earth.


A tabletop exercise of a simulated emergency is commonly used in disaster management planning to help inform involved players of important aspects of a possible disaster and identify issues for accomplishing a successful response. In next week’s exercise, attendees at the conference will play out a fictional NEO impact scenario developed by the NASA Jet Propulsion Laboratory’s Center for NEO Studies (CNEOS).


“These exercises have really helped us in the planetary defense community to understand what our colleagues on the disaster management side need to know,” said Lindley Johnson, NASA’s Planetary Defense Officer. “This exercise will help us develop more effective communications with each other and with our governments.”


This type of exercise is also specifically identified as part of the National Near-Earth Object Preparedness Strategy and Action Plan developed over a two-year period and published by the White House in June 2018.


These exercises are not tightly scripted. The point is to investigate how NEO observers, space agency officials, emergency managers, decision makers, and citizens might respond to an actual impact prediction and evolving information. Next week’s exercise events will occur over the five days of the conference, with exercise leaders briefing participants on the status of the scenario at the end of each day and soliciting response ideas and feedback, based on the latest fictional data.


The scenario begins with the fictional premise that on March 26, astronomers “discovered” a NEO they consider potentially hazardous to Earth. After a “few months” of tracking, observers predict that this NEO – dubbed 2019 PDC – poses a 1 in 100 chance of impact with Earth in 2027 (in real life, the international community has decided that a 1 in 100 chance of impact is the threshold for action). Participants in this exercise will discuss potential preparations for asteroid reconnaissance and deflection missions and planning for mitigation of a potential impact’s effects.



Near Earth Asteroids. Image Credit: ESA

NASA has participated in six NEO impact exercises so far – three at Planetary Defense Conferences (2013, 2015, 2017) and three jointly with the Federal Emergency Management Agency (FEMA). The three NASA-FEMA exercises included representatives of several other federal agencies, including the Departments of Defense and State. Each exercise builds on lessons learned in the previous exercise.


What NASA has learned from working with FEMA is that emergency management officials are not focused on the scientific details about the asteroid. “What emergency managers want to know is when, where, and how an asteroid would impact and the type and extent of damage that could occur,” said Leviticus Lewis, Response Operations Division for FEMA.


But the scientific details are what determine these things, so NASA-funded researchers continue to develop capabilities for determining more exact possible impact locations and effects, based on what could be observed about an asteroid’s position, orbital motion and characteristics, to be ready to produce the most accurate predictions possible in the event an actual impact threat were discovered.


“NASA and FEMA will continue to conduct periodic exercises with a continually widening community of U.S .government agencies and international partners,” said Johnson. “They are a great way for us to learn how to work together and meet each other’s needs and the objectives laid out in the White House National NEO Preparedness Action Plan.”


Related links:


Planetary Defense Coordination Office (PDCO): https://www.nasa.gov/planetarydefense


2019 Planetary Defense Conference: http://pdc.iaaweb.org/


NASA Jet Propulsion Laboratory’s Center for NEO Studies (CNEOS): https://cneos.jpl.nasa.gov/pd/cs/pdc19/


National Near-Earth Object Preparedness Strategy and Action Plan: https://www.nasa.gov/feature/federal-government-releases-national-near-earth-object-preparedness-plan


NEO impact exercises: https://cneos.jpl.nasa.gov/pd/cs/


Asteroids: https://www.nasa.gov/mission_pages/asteroids/main/index.html


Images (mentioned), Text, Credits: NASA/Tricia Talbert.


Greetings, Orbiter.chArchive link


More Head and Eye Pressure Research and Dragon Robotics Training


ISS — Expedition 59 Mission patch.


April 24, 2019


The Expedition 59 crew is unloading one U.S. cargo ship today and preparing for the arrival of another after it launches from Florida next week. The orbital residents also continued exploring how microgravity impacts the human body and a variety of terrestrial materials.


Astronauts Christina Koch and David Saint-Jacques worked Wednesday afternoon to offload some of the 7,600 pounds of cargo the Cygnus space freighter delivered last week. Saint-Jacques is also training today to capture the SpaceX resupply ship with the Canadarm2 robotic arm when it arrives next Thursday. Dragon will be the sixth spaceship parked at the station and occupy the Harmony module’s Earth-facing port.



Image above: Astronauts David Saint-Jacques and Anne McClain practice Canadarm2 robotics maneuvers and spacecraft capture techniques on the robotics workstation in the U.S. Destiny laboratory module. Image Credit: NASA.


The duo also split the day working with a variety of biomedical hardware and research gear to ensure healthy astronauts and successful space research. Koch and Saint-Jacques participated in ultrasound scans for ongoing health checks. Koch then explored the feasibility of manufacturing fiber optic cables in space. Saint-Jacques set up Kubik incubator hardware inside Europe’s Columbus lab module.



International Sapce Station (ISS). Animation Credit: NASA

NASA Flight Engineers Anne McClain and Nick Hague were back collecting more blood, urine and saliva samples today. The samples are spun in a centrifuge, stowed in a science freezer then analyzed for the long-running Fluid Shifts study. The experiment seeks to understand and prevent the upward flow of body fluids in space that cause head and eye pressure in astronauts.


McClain then studied how living aboard the International Space Station affects her perception and cognition. Hague researched and photographed a variety of coating materials for their thermal protection and optical recognition properties.


Related links:


Expedition 59: https://www.nasa.gov/mission_pages/station/expeditions/expedition59/index.html


Canadarm2 robotic arm: https://www.nasa.gov/mission_pages/station/structure/elements/mobile-servicing-system.html


Harmony module: https://www.nasa.gov/mission_pages/station/structure/elements/harmony


Space research: https://www.nasa.gov/mission_pages/station/research/index.html


Fiber optic cables: http://www.asc-csa.gc.ca/eng/astronauts/canadian/active/bio-david-saint-jacques.asp


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


Fluid Shifts: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1126


Perception and cognition: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=979


Coating materials: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1749


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


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


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


Best regards, Orbiter.chArchive link


Far from Westeros, a Three-Eyed Raven Helps NASA Find Its Way

Perched on the outside of the International Space Station is Raven—a technology-filled module that helps NASA develop a relative navigation capability, which is essentially autopilot for spacecraft. Raven has been testing technologies to enable autonomous rendezvous in space, which means the ability to approach things in space without human involvement, even from the ground.


image

Developed by the Satellite Servicing Projects Division (SSPD), our three-eyed Raven has visible, infrared, and Lidar sensors and uses those “eyes” to image and track visiting spacecraft as they come and go from the space station. Although Raven is all-seeing, it only sees all in black and white. Color images do not offer an advantage in the case of Raven and Restore-L, which also utilize infrared and Lidar sensors.


The data from Raven’s sensors is sent to its processor, which autonomously sends commands that swivel Raven on its gimbal, or pointing system. When Raven turns using this system, it is able to track a vehicle. While these maneuvers take place, NASA operators evaluate the movements and make adjustments to perfect the relative navigation system technologies. 



A few days ago, Raven completed its 21st observation of a spacecraft when it captured images of Northrop Grumman’s Cygnus vehicle delivering science investigations and supplies as part of its 11th commercial resupply services mission, including another SSPD payload called the Robotic External Leak Locator.


image

And just last month, Raven celebrated its two-year anniversary in space, marking the occasion with an observation of SpaceX’s Crew Dragon during the Demo-1 mission.


image

What is this—a spacecraft for ants??


While this shot of Dragon isn’t terribly impressive because of where the spacecraft docked on station, Raven has captured some truly great images when given the right viewing conditions. 


From SpaceX Dragon resupply mission observations…


image

…to Cygnus supply vehicles.


image

Raven has observed six unique types of spacecraft. 


It has also conducted a few observations not involving spacecraft, including the time it captured Hurricane Irma…


image

…or the time it captured station’s Dextre arm removing the Robotic Refueling Mission 3 payload, another mission developed by SSPD, from the Dragon spacecraft that delivered it to the orbiting laboratory.


image

image

Thus far, Raven has had a great, productive life aboard the station, but its work isn’t done yet! Whether it’s for Restore-L, which will robotically refuel a satellite, or getting humans to the Moon or Mars, the technologies Raven is demonstrating for a relative navigation system will support future NASA missions for decades to come.


image

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


‘The King Stone’, The Rollright Stones, Oxfordshire, 22.4.19.


‘The King Stone’, The Rollright Stones, Oxfordshire, 22.4.19.




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Duct Tape Breast cancers often develop from changes inside a…


Duct Tape


Breast cancers often develop from changes inside a single cell, but examining the early stages of a tumour forming – tumorigenesis – is challenged by messy chemicals that block the laser light used by high-powered microscopes. Here a new ‘clearing’ technique washes these away leaving an intact mouse breast duct behind. Assembling several images together into a 3D model, we can now fly through the duct, inspecting the insides like an engineer or an architect might explore a tunnel looking for tiny flaws, although 100,000 times smaller. Coloured fluorescence highlights cells in different layers of the breast tissue – in early cancers, some of these cells may change into mesenchymal cells, helping a cancer to evolve and spread. Combining microscopy with other techniques to assess genetic changes may help to spot breast cells more prone to becoming cancerous, leading to earlier and more effective treatment.


Written by John Ankers



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‘The King’s Men’, The Rollright Stones, Oxfordshire, 22.4.19.

‘The King’s Men’, The Rollright Stones, Oxfordshire, 22.4.19.









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