Microscope allows gentle, continuous imaging of light-sensitive corals

Corals are "part animal, part plant, and part rock -- and difficult to figure out, despite being studied for centuries," says Philippe Laissue of University of Essex, a Whitman Scientist at the Marine Biological Laboratory. Many corals are sensitive to bright light, so capturing their dynamics with traditional microscopes is a challenge.

To work around their photosensitivity, Laissue developed a custom light-sheet microscope (the L-SPI) that allows gentle, non-invasive observation of corals and their polyps in detail over eight continuous hours, at high resolution. He and his colleagues, including MBL Associate Scientist and coral biologist Loretta Roberson, published their findings this week in Scientific Reports.

Coral reefs, made up of millions of tiny units called polyps, are extremely important ecosystems, both for marine life and for humans. They harbor thousands of marine species, providing food and economic support for hundreds of millions of people. They also protect coasts from waves and floods, and hold great potential for pharmaceutical and biotechnological discovery.

But more than half of the world's coral reefs are in severe decline. Climate change and other human influences are gravely threatening their survival. As ocean temperatures rise, coral bleaching is afflicting reefs worldwide. In coral bleaching, corals expel their symbiotic algae and become more susceptible to death.

"The L-SPI opens a window on the interactions and relationship between the coral host, the symbiotic algae living in their tissues, and the calcium carbonate skeleton they build in real time," Roberson says. "We can now track the fate of the algae during [coral] bleaching as well as during initiation of the symbiosis."

Roberson is also using Laissue's imaging technology to measure damage to corals from "bioeroders" -- biological agents like algae and sponges that break down a coral's skeleton, a problem exacerbated by ocean acidification and increasing water temperatures.

Story Source:

Materials provided by Marine Biological Laboratory. Original written by Diana Kenney. Note: Content may be edited for style and length.

#Nature | https://sciencespies.com/nature/microscope-allows-gentle-continuous-imaging-of-light-sensitive-corals/

SpaceX launches a U.S. Space Force GPS 3 satellite, recovers rocket’s first stage

This was the first time SpaceX recovered a booster following a National Security Space Launch mission.

WASHINGTON — A SpaceX Falcon 9 rocket launched a U.S. Space Force GPS 3 satellite on June 30. The rocket lifted off at 4:10 p.m. Eastern from Cape Canaveral, Florida,

About eight minutes after liftoff, SpaceX landed the Falcon 9’s brand-new first stage on the “Just Read the Instructions” droneship stationed in the Atlantic Ocean.

This was the Falcon 9’s 87th successful mission and the 49th first stage recovered by SpaceX. It also marked the first time the company recovered a booster following a National Security Space Launch mission.

The payload, the third GPS 3 satellite made by Lockheed Martin, separated from the rocket’s second stage approximately one hour and 29 minutes after liftoff. The satellite was deployed in a medium Earth orbit at an altitude of about 12,550 miles.

SpaceX’s first launch of a GPS 3 satellite was on Dec. 23, 2018. Following the June 30 mission, the company is under contract to launch three more GPS 3 satellites over the next two years.

Tonya Ladwig, vice president of Lockheed Martin Space Systems’ Navigation Systems Division said GPS 3 satellites provide three times greater accuracy and up to eight times more anti-jamming power than the earlier generation of satellites. It also adds a new L1C civil signal.

The new GPS 3 will join a constellation of 31 GPS satellites currently in operation. Each satellite circles the earth twice per day.

#Space | https://sciencespies.com/space/spacex-launches-a-u-s-space-force-gps-3-satellite-recovers-rockets-first-stage/

Astronomers have located the centre of the Solar System to within 100 metres

When you picture the Solar System in your head, most people would think of the Sun, stolid and stationary in the centre, with everything else whizzing about around it. But every body in the Solar System also exerts its own gravitational tug on the star, causing it to move around just a tiny bit.

Therefore, the precise gravitational centre (or barycentre) of the Solar System is not smack-bang in the middle of the Sun, but somewhere closer to its surface, just outside it. But it hasn't been easy for us to figure out exactly where this barycentre is, due to the myriad gravitational influences at play.

Now, using specially designed software, an international team of astronomers has narrowed down the location of our Solar System's barycentre to within 100 metres (328 feet) - and it could vastly improve our measurements of gravitational waves.

It all has to do with pulsars. These dead stars can rotate extremely fast, on millisecond timescales, shooting beams of electromagnetic radiation from their poles. If they're oriented just right, these beams flash past Earth like a very fast cosmic lighthouse, creating a pulsed signal that's extremely regular.

This regular pulse is useful for all sorts of things, from probing the interstellar medium to a potential navigation system.

In recent years, observatories including the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) have started using them to look for low-frequency gravitational waves, since gravitational waves should cause very subtle disturbances in the timing of a whole array of pulsars across the sky.

"Using the pulsars we observe across the Milky Way galaxy, we are trying to be like a spider sitting in stillness in the middle of her web," explained astronomer and physicist Stephen Taylor of Vanderbilt University and the NANOGrav Collaboration.

"How well we understand the Solar System barycenter is critical as we attempt to sense even the smallest tingle to the web."

That's because errors in the calculation of Earth's position in relation to the Solar System barycentre can affect our measurements of pulsar timing, which in turn can affect our searches for low-frequency gravitational waves.

Part of the problem is Jupiter. By a very large margin, it has the strongest gravitational effect on the Sun - the tugs of the other planets are minute in comparison. We know how long Jupiter takes to orbit the Sun - about 12 Earth years - but our understanding of this orbit is incomplete.

Previously, estimations of the location of the barycentre have relied on Doppler tracking - how the light from objects changes as we (or our instruments) move towards or away from them - to calculate the orbits and masses of the planets. But any errors in these masses and orbits can introduce errors that might look a lot like gravitational waves.

And when the team used these existing datasets to analyse NANOGrav data, they kept getting inconsistent results.

"We weren't detecting anything significant in our gravitational wave searches between solar system models, but we were getting large systematic differences in our calculations," said astronomer Michele Vallisneri of NASA's Jet Propulsion Laboratory.

"Typically, more data delivers a more precise result, but there was always an offset in our calculations."

This is where the team's software enters the picture. It's called BayesEphem, and it's designed to model and correct for those uncertainties in Solar System orbits most relevant to gravitational wave searches using pulsars - Jupiter in particular.

When the team applied BayesEphem to the NANOGrav data, they were able to place a new upper limit on the gravitational wave background and detection statistics. And they were able to calculate a new, more precise location for the Solar System barycentre that, going forward, could enable much more accurate low-frequency gravitational wave detections.

"Our precise observation of pulsars scattered across the galaxy has localised ourselves in the cosmos better than we ever could before," Taylor said.

"By finding gravitational waves this way, in addition to other experiments, we gain a more holistic overview of all different kinds of black holes in the Universe."

The research has been published in The Astrophysical Journal.

#Space | https://sciencespies.com/space/astronomers-have-located-the-centre-of-the-solar-system-to-within-100-metres/

Insects' dazzling colours have been preserved in Myanmar amber for 99 million years

When you think of the colour scheme sported by the prehistoric world of the dinosaurs, greens and browns typically spring to mind.

But more and more research has shown that millions of years ago, vibrant, vivid colours were everywhere in nature, just like they are today. The latest evidence - 99-million-year-old insects caught in amber with incredible colours of purple, blue, and metallic green.

One of the reasons it's so hard for us to know the colours of prehistoric creatures is due to what's left from them - a fossilised bone can't convey what colour the animal was. But lately, scientists have been working out pigments from fossilised feathers; or, in the case of this latest study, used Burmese amber to peer into the world of ancient colours.

"The type of colour preserved in the amber fossils is called structural colour. It is caused by microscopic structure of the animal's surface," explained palaeontologist Pan Yanhong from the Chinese Academy of Science.

"The surface nanostructure scatters light of specific wavelengths and produces very intense colours. This mechanism is responsible for many of the colours we know from our everyday lives."

A number of insects studied by the researchers. (Cai et al., PRSB, 2020)

Structural colour is what makes peacock feathers and butterfly scales appear iridescent; in this case, it was created by the outer cuticle of the insect's exoskeleton.

The team collected 35 amber specimens containing ancient insects that also possessed these intense structural colours.

The vast majority of the specimens were either cuckoo wasps (family Chrysididae) or chalcid wasps (part of the superfamily Chalcidoidea). The amber-encased creatures showed off their metallic bluish-green, yellowish-green, purplish-blue, or even vibrant green bodies.

Interestingly enough, the cuckoo wasps in amber (see, for example, the first green insect in the series of images above) were nearly the same colour as the cuckoo wasps that are around today.

A modern cuckoo wasp. (Wasrts/Wikimedia/CC BY 4.0)

"The colour displayed by fossils can often be misleading because fine nanostructures responsible for coloration can be altered during fossilisation. However, the original colour of fossils can be reconstructed using theoretical modelling," the team writes in their paper.

"The calculated reflectance peaks match the observed metallic bluish-green coloration of the mesopleuron of our studied wasp, confirming that extremely fine nanostructures can be preserved in Mesozoic amber."

The team also thinks they have an explanation for why only some amber insect fossils retain the colouration of the animals inside.

After cutting through the exoskeleton of two of the vibrant wasps and one comparatively dull fossil, they found that in the dull sample, the cuticular structures which create the structural colours are damaged. In the colourful fossils, the insects' exoskeletons and the nanostructures that scatter light were still preserved.

While we admire the discoveries, it's important to note the palaeontology community is currently debating whether the scientific information that can be gleaned from these specimens collected and sold in Myanmar is worth the price of the potential human consequences, including the persecution of ethnic minorities.

In the last few years, amber has given us incredible creatures from the Cretaceous. These animals lived nearly 100 million years ago, and findings include the skull of the smallest dinosaur, some tiny frogs, a bird with a weirdly long toe, and many, many more.

The research has been published in Proceedings of the Royal Society B: Biological Sciences.

#Nature | https://sciencespies.com/nature/insects-dazzling-colours-have-been-preserved-in-myanmar-amber-for-99-million-years/

See the Face of a Man Whose Skull Was Mounted on a Stake 8,000 Years Ago

Some 8,000 years ago, the skull of a Scandinavian man in his 50s was impaled on a wooden stake in Sweden. Now, a new facial reconstruction by Swedish forensic artist Oscar Nilsson allows modern viewers to envision this mysterious individual’s prominent cheekbones, blue eyes and brown hair, reports Kristin Romey for National Geographic.

Archaeologists found the man’s cranium—as well as the skulls of eight other adults and one infant—in the boggy sediment of the Kanaljorden excavation site in Motala, Sweden, in 2012. The discovery marked the first archaeological evidence of Mesolithic hunter-gatherers mounting human skulls on stakes.

Kanaljorden is of particular interest because the remains found there were arranged in such an uncommon, purposeful way, according to Elaina Zachos of National Geographic. The human burial, which also included animal bones, was placed on a stone platform submerged in the middle of a small lake. Researchers found remnants of wooden stakes inside the skulls of two of the men.

To give one of these ancient humans—a man nicknamed “Ludvig”—a face, Nilsson scanned his skull and created a 3-D plastic replica of it, reports George Dvorsky for Gizmodo. The forensic artist then drew on genetic evidence to capture Ludvig’s pale complexion and hair and eye color. But the biggest challenge stemmed from what the skull lacked.

DNA analysis and CT scans of the 8,000-year-old skull informed the facial reconstruction.

(Oscar Nilsson)

“The jaw was missing, so I had to calculate and reconstruct it from studying and measuring the skull,” Nilsson tells Smithsonian magazine via email. “This is time consuming and difficult, [and] the error margin of course gets bigger when such a vital part is missing.”

Though the majority of the adult Mesolithic skulls in the grave had no jawbones, a 2018 paper on the find detailed the presence of jawbones from various animals, including bears, wild boars, deer, moose and badgers.

The wild boar remains inspired Nilsson to give Ludvig a cloak made of the animal’s hide.

“He wears the skin from a wild boar,” explains Nilsson to Live Science’s Laura Geggel. “We can see from how the human skulls and animal jaws were found that they clearly meant a big deal in their cultural and religious beliefs.”

Ludvig’s hairstyle also takes its cue from boars. The front is similar to the short bristles on the animal’s body, while the back features a wisp of hair reminiscent of a tail.

Nilsson tells Smithsonian that he hopes this styling will make people wonder how Ludvig cut his hair. Sharp flint tools could have done the job, but the hunter-gatherer probably would have needed help from a Mesolithic “hairdresser.”

The front of Ludvig's hair is similar to the short bristles on boars’ bodies, while the back features a wisp reminiscent of a pig’s tail.

(Oscar Nilsson)

Researchers are unsure of Ludvig’s exact cause of death. The facial reconstruction includes a prominent one-inch wound on the top of his skull, but the injury showed signs of healing. Puzzlingly, the adult skulls found at the burial site exhibit distinctive trauma patterns: Females sustained injuries on the back and right side of the head, while males suffered a single blow to the top of the head, according to National Geographic.

“Somebody gave them love and care after this [trauma] and healed them back to life again,” study co-author Fredrik Hallgren, an archaeologist at the Cultural Heritage Foundation in Västerås, Sweden, told Live Science in 2018.

Why Ludvig’s skull wound up on a wooden stake is also unclear. Prior excavations suggest that Mesolithic hunter-gatherers tended to respect the bodily integrity of the dead. And the practice of decapitating enemies only emerged later in history.

“The fact that two crania were mounted [on stakes] suggests that they have been on display, in the lake or elsewhere,” co-author Anna Kjellström, an archeologist at Stockholm University, told Gizmodo in 2018.

The dig at Kanaljorden didn’t yield any direct evidence that the people buried there were decapitated or had their jaws forcibly removed. Archaeologists say the individuals’ heads and lower jaws may have been removed after significant decomposition took place, perhaps in the context of another burial.

As Nilsson tells Smithsonian, he hopes the facial reconstruction will connect people not just to history and archaeology, but to the power of science, which provided the intimate details needed to bring Ludvig back to life.

#News | https://sciencespies.com/news/see-the-face-of-a-man-whose-skull-was-mounted-on-a-stake-8000-years-ago/

See the Face of a Man Whose Skull Was Mounted on a Stake 8,000 Years Ago

Some 8,000 years ago, the skull of a Scandinavian man in his 50s was impaled on a wooden stake in Sweden. Now, a new facial reconstruction by Swedish forensic artist Oscar Nilsson allows modern viewers to envision this mysterious individual’s prominent cheekbones, blue eyes and brown hair, reports Kristin Romey for National Geographic.

Archaeologists found the man’s cranium—as well as the skulls of eight other adults and one infant—in the boggy sediment of the Kanaljorden excavation site in Motala, Sweden, in 2012. The discovery marked the first archaeological evidence of Mesolithic hunter-gatherers mounting human skulls on stakes.

Kanaljorden is of particular interest because the remains found there were arranged in such an uncommon, purposeful way, according to Elaina Zachos of National Geographic. The human burial, which also included animal bones, was placed on a stone platform submerged in the middle of a small lake. Researchers found remnants of wooden stakes inside the skulls of two of the men.

To give one of these ancient humans—a man nicknamed “Ludvig”—a face, Nilsson scanned his skull and created a 3-D plastic replica of it, reports George Dvorsky for Gizmodo. The forensic artist then drew on genetic evidence to capture Ludvig’s pale complexion and hair and eye color. But the biggest challenge stemmed from what the skull lacked.

DNA analysis and CT scans of the 8,000-year-old skull informed the facial reconstruction.

(Oscar Nilsson)

“The jaw was missing, so I had to calculate and reconstruct it from studying and measuring the skull,” Nilsson tells Smithsonian magazine via email. “This is time consuming and difficult, [and] the error margin of course gets bigger when such a vital part is missing.”

Though the majority of the adult Mesolithic skulls in the grave had no jawbones, a 2018 paper on the find detailed the presence of jawbones from various animals, including bears, wild boars, deer, moose and badgers.

The wild boar remains inspired Nilsson to give Ludvig a cloak made of the animal’s hide.

“He wears the skin from a wild boar,” explains Nilsson to Live Science’s Laura Geggel. “We can see from how the human skulls and animal jaws were found that they clearly meant a big deal in their cultural and religious beliefs.”

Ludvig’s hairstyle also takes its cue from boars. The front is similar to the short bristles on the animal’s body, while the back features a wisp of hair reminiscent of a tail.

Nilsson tells Smithsonian that he hopes this styling will make people wonder how Ludvig cut his hair. Sharp flint tools could have done the job, but the hunter-gatherer probably would have needed help from a Mesolithic “hairdresser.”

The front of Ludvig's hair is similar to the short bristles on boars’ bodies, while the back features a wisp reminiscent of a pig’s tail.

(Oscar Nilsson)

Researchers are unsure of Ludvig’s exact cause of death. The facial reconstruction includes a prominent one-inch wound on the top of his skull, but the injury showed signs of healing. Puzzlingly, the adult skulls found at the burial site exhibit distinctive trauma patterns: Females sustained injuries on the back and right side of the head, while males suffered a single blow to the top of the head, according to National Geographic.

“Somebody gave them love and care after this [trauma] and healed them back to life again,” study co-author Fredrik Hallgren, an archaeologist at the Cultural Heritage Foundation in Västerås, Sweden, told Live Science in 2018.

Why Ludvig’s skull wound up on a wooden stake is also unclear. Prior excavations suggest that Mesolithic hunter-gatherers tended to respect the bodily integrity of the dead. And the practice of decapitating enemies only emerged later in history.

“The fact that two crania were mounted [on stakes] suggests that they have been on display, in the lake or elsewhere,” co-author Anna Kjellström, an archeologist at Stockholm University, told Gizmodo in 2018.

The dig at Kanaljorden didn’t yield any direct evidence that the people buried there were decapitated or had their jaws forcibly removed. Archaeologists say the individuals’ heads and lower jaws may have been removed after significant decomposition took place, perhaps in the context of another burial.

As Nilsson tells Smithsonian, he hopes the facial reconstruction will connect people not just to history and archaeology, but to the power of science, which provided the intimate details needed to bring Ludvig back to life.

#News | https://sciencespies.com/news/see-the-face-of-a-man-whose-skull-was-mounted-on-a-stake-8000-years-ago/

House, Senate continue work on space-related legislation

WASHINGTON — Key members of the House and Senate say they continue to work on space-related legislation, including a NASA authorization bill, but the two branches of Congress appear to remain far apart on their bills.

At the time the coronavirus pandemic hit in March, stopping most legislative activity other than relief measures and other critical legislation, the House Science Committee was considering a NASA authorization bill. A full committee markup of the bill, introduced in January, was expected in March but never scheduled.

The committee may soon take up the bill. “We’re about to take it up and mark it up in the full committee,” Rep. Kendra Horn (D-Okla.), chair of the House space subcommittee, said at a June 24 meeting of the Advisory Committee on Commercial Remote Sensing (ACCRES) held online. “We’re continuing to work towards that end. I think it is important to get that through.”

That bill made waves when it was introduced in January because, in part, of its provisions regarding NASA lunar lander development. That bill directed NASA to own and operate the lander, rather than use public-private partnerships as it has been doing through the Human Landing System program. It also favored a lander that could be launched on a single Space Launch System rocket, rather than launching components on commercial vehicles and integrating them in lunar orbit or at the lunar Gateway.

Horn said in an interview in late February that, since a subcommittee markup in late January, the committee had made changes to the bill, including the lunar lander provisions, but declined at the time to discuss the details since those changes were still being developed

That markup may be done through a remote hearing, rather than one held in person. “We have just begun having remote hearings over the past couple of weeks” by both the full committee and her subcommittee, which held one on commercial air travel June 23. “I am hopeful that we will be able to take this up and get it through this year.”

Horn said her subcommittee may also continue a series of hearings it started before the pandemic on space traffic management issues. “Space domain awareness and space traffic management are going to continue to be at the forefront,” she said.

The House version of a NASA authorization bill differs sharply from a Senate version that the Senate Commerce Committee approved last November. Sen. Ted Cruz (R-Texas), chair of the Senate space subcommittee, criticized the House in February for failing to cooperate on the legislation, claiming the Democrat-led House treats “space as a partisan football.”

Cruz repeated that criticism in a separate presentation to ACCRES June 23. “At the beginning of this Congress, I was hopeful that we would continue to see the same bipartisan, productive cooperation on space that marked my first six years in the Senate,” he said. “That hasn’t proven to be the case.”

He focused his comments at the meeting on a separate bill, the Space Frontier Act, which deals with commercial space issues, such as revisions to the Land Remote Sensing Policy Act of 1992 that governs commercial remote sensing. In the previous Congress, the Senate approved the bill by unanimous consent but the bill failed to get a two-thirds majority required in the House to pass by suspension of the rules.

Cruz introduced a new version of the bill last year that the Senate Commerce Committee approved but has yet to be taken up by the full Senate. Cruz tried to include the bill as an amendment to a defense authorization bill, but that effort failed, which he blamed on the House.

“The House has all but refused to tackle, or even begin to take on, the big issues important to space,” he said. “They’ve tried to directly scuttle legislative efforts in the Senate to move the ball forward.”

In the House, Rep. Brian Babin (R-Texas), ranking member of the space subcommittee, has continued to advocate for a bill he introduced called the American Space Commerce Free Enterprise Act, which includes some of the changes in the Senate’s Space Frontier Act. Speaking at the ACCRES meeting June 23, he argued the bill is needed to update the 1992 act that provides the basis for commercial remote sensing regulations.

“The bill updates the regulatory process and reorganizes the Department of Commerce to enable a 21st century commercial remote sensing industry in the United States,” he said. The bill, introduced last year, is pending action by the House Science Committee.

Such legislation, though, is likely to remain secondary to “must-pass” legislation, including future pandemic relief measures, a defense authorization bill and fiscal year 2021 appropriations. The House Appropriations Committee is expected to start markups of its 2021 spending bills as soon as the week of July 6.

The lack of appropriations hearings during the pandemic has meant there’s little insight into how members of Congress will respond to NASA’s $25.2 billion budget proposal released in February.

“I don’t think I have a better crystal ball than anyone else,” said Jim Reuter, NASA associate administrator for space technology, when asked about prospects for an appropriations bill during a June 29 webinar organized by the American Institute of Aeronautics and Astronautics.

He expected NASA to at least start the year on a continuing resolution that funds agency programs at fiscal year 2020 levels, something that has become commonplace in the appropriations process. “We’ve very optimistic about the activities that are going on” regarding appropriations in Congress, he added, saying he hoped the appropriations would be finalized “shortly after” the November election.

#Space | https://sciencespies.com/space/house-senate-continue-work-on-space-related-legislation/

A massive star has disappeared from a distant galaxy, and no one's sure where it went

Massive stars aren't like your car keys. They're not going to disappear under a pile of mail on your kitchen counter, or end up in the washing machine. But a massive star that astronomers were observing for a decade now appears to be totally missing.

The star, in the very late stages of its lifespan, was shining brightly between 2001 and 2011, when different teams of astronomers were regularly observing it to obtain more information on how stars end their lives. But in observations obtained in 2019, the star's signature was completely absent.

Then the mystery deepened. When researchers looked back through archival data from 2011 and 2016, looking for some clue as to the star's disappearance, its light was present in the former, but missing in the latter. Somehow, after 2011, the star vanished without a trace.

And there's a really exciting possibility - that the star collapsed down into a black hole, without the supernova that has previously been thought a necessary component of such events.

"If true," said astrophysicist Andrew Allan of Trinity College Dublin in Ireland, "this would be the first direct detection of such a monster star ending its life in this manner."

It's a little hard to figure out exactly what happened, though. It all went down in a dwarf galaxy called PHL 293B, 75 million light-years away. At that distance, making out individual stars is impossible - we simply don't have the technology.

However, there's a type of star called a luminous blue variable that has a recognisable light signature. These stars are massive - on the supergiant or hypergiant scale - and at the end of their lives. As such, they are extremely bright and unstable, and their light can vary dramatically in both brightness and spectrum as they undergo outbursts and eruptions.

In the earlier observations of the dwarf galaxy, this signature was present, indicating a star between 2.5 and 3.5 million times as bright as the Sun. So when the team turned all four of the European Southern Observatory's Very Large Telescope optical telescopes towards PHL 293B in August 2019, the absence was shocking.

"It would be highly unusual for such a massive star to disappear without producing a bright supernova explosion," Allan said.

In recent years, however, evidence has started to emerge that stars can indeed collapse directly into black holes without undergoing a supernova explosion. In 2017, a paper was published on a similar phenomenon in a galaxy 22 million light-years away - a red giant star that brightened suddenly before blinking out of existence, leading astronomers to hypothesise that the star had undergone a failed supernova before collapsing.

Based on their observations, the team believes the star in PHL 293B was in an eruptive state between 2001 and 2011. From this point, there are two main possibilities.

The first is that the star grew slightly dimmer, and became shrouded in a cloud of dust as it ejected material into the space around it - much like the dust cloud that may (or may not) have obscured Milky Way's red giant star Betelgeuse earlier this year. In this scenario, the star could have continued erupting behind its cloud of dust - we just can't see it any more because, well, cloud of dust.

Near-infrared observations between 2009 and 2019 ruled out a cloud of hot dust, but mid-infrared observations that could confirm or rule out cooler dust are yet to be taken, so this scenario is still very much on the table.

In the other scenario, the eruption could have been the star's death throes, ending abruptly at some point after 2011 as the star collapsed into a black hole. If the star had an initial mass between 85 and 120 times that of the Sun - just below the range of a pair-instability supernova, in which the star is blown to smithereens instead of collapsing.

It's not impossible that the star underwent an undetected supernova, but such a massive star as a luminous blue variable would be expected to produce a supernova afterglow that shines in the sky for at least five years following the kaboom.

"We may have detected one of the most massive stars of the local Universe going gently into the night," said astrophysicist Jose Groh of Trinity College Dublin.

It's impossible to know for certain with the current data. Only future observations across a range of wavelengths can shed light on the mystery of the missing star.

The research has been published in the Monthly Notices of the Royal Astronomical Society.

#Space | https://sciencespies.com/space/a-massive-star-has-disappeared-from-a-distant-galaxy-and-no-ones-sure-where-it-went/

Asteroid impact, not volcanoes, made the Earth uninhabitable for dinosaurs

Modelling of the Chicxulub asteroid impact 66 million years ago shows it created a world largely unsuitable for dinosaurs to live in.

The asteroid, which struck the Earth off the coast of Mexico at the end of the Cretaceous era 66 million years ago, has long been believed to be the cause of the demise of all dinosaur species except those that became birds.

However, some researchers have suggested that tens of thousands of years of large volcanic eruptions may have been the actual cause of the extinction event, which also killed off almost 75% of life on Earth.

Now, a research team from Imperial College London, the University of Bristol and University College London has shown that only the asteroid impact could have created conditions that were unfavourable for dinosaurs across the globe.

They also show that the massive volcanism could also have helped life recover from the asteroid strike in the long term. Their results are published today in Proceedings of the National Academy of Sciences.

Lead researcher Dr Alessandro Chiarenza, who conducted this work whilst studying for his PhD in the Department of Earth Science and Engineering at Imperial, said: "We show that the asteroid caused an impact winter for decades, and that these environmental effects decimated suitable environments for dinosaurs. In contrast, the effects of the intense volcanic eruptions were not strong enough to substantially disrupt global ecosystems.

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"Our study confirms, for the first time quantitatively, that the only plausible explanation for the extinction is the impact winter that eradicated dinosaur habitats worldwide."

The asteroid strike would have released particles and gases high into the atmosphere, blocking out the Sun for years and causing permanent winters. Volcanic eruptions also produce particles and gases with Sun-blocking effects, and around the time of the mass extinction there were tens of thousands of years of eruptions at the Deccan Traps, in present-day India.

To determine which factor, the asteroid or the volcanism, had more climate-changing power, researchers have traditionally used geological markers of climate and powerful mathematical models. In the new paper, the team combined these methods with information about what kinds of environmental factors, such as rainfall and temperature, each species of dinosaur needed to thrive.

They were then able to map where these conditions would still exist in a world after either an asteroid strike or massive volcanism. They found that only the asteroid strike wiped out all potential dinosaur habitats, while volcanism left some viable regions around the equator.

Co-lead author of the study Dr Alex Farnsworth, from the University of Bristol, said: "Instead of only using the geologic record to model the effect on climate that the asteroid or volcanism might have caused worldwide, we pushed this approach a step forward, adding an ecological dimension to the study to reveal how these climatic fluctuations severely affected ecosystems."

Co-author Dr Philip Mannion, from University College London, added: "In this study we add a modelling approach to key geological and climate data that shows the devastating effect of the asteroid impact on global habitats. Essentially, it produces a blue screen of death for dinosaurs."

Although volcanoes release Sun-blocking gases and particles, they also release carbon dioxide, a greenhouse gas. In the short term after an eruption, the Sun-blockers have a larger effect, causing a 'volcanic winter'. However, in the longer term these particles and gases drop out of the atmosphere, while carbon dioxide stays around and builds up, warming the planet.

After the initial drastic global winter caused by the asteroid, the team's model suggests that in the longer term, volcanic warming could have helped restore many habitats, helping new life that evolved after the disaster to thrive.

Dr Chiarenza said: "We provide new evidence to suggest that the volcanic eruptions happening around the same time might have reduced the effects on the environment caused by the impact, particularly in quickening the rise of temperatures after the impact winter. This volcanic-induced warming helped boost the survival and recovery of the animals and plants that made through the extinction, with many groups expanding in its immediate aftermath, including birds and mammals."

#Nature | https://sciencespies.com/nature/asteroid-impact-not-volcanoes-made-the-earth-uninhabitable-for-dinosaurs/

300-Pound, Wombat-Like Creature Once Roamed Australia

Paleontologists announced the discovery of an extinct Australian mammal resembling a 300-pound wombat in new research published in the journal Scientific Reports.

If you’re struggling to picture a wombat, imagine a stocky, short-limbed ball of burrowing marsupial fluff, as Joshua Sokol helpfully describes for the New York Times. (Humans find wombats so adorable that Maria Island National Park in Tasmania had to issue a special advisory asking visitors to stop petting them, trying to take selfies with them and generally attempting to squeeze them for ever and ever.)

The next crucial step to imagining this 25-million-year-old animal is to take the trundling wombat you’ve conjured and make it the size of a black bear, which is the living animal that study co-author Mike Archer, a paleontologist at the University of New South Wales, used to approximate the new species’ size in a statement.

The big-boned creature was named Mukupirna nambensis for the words muku (“bones”) and pirna (“big”) of the indigenous Dieri and Malyangapa languages spoken near where the fossil was unearthed.

The find included a partial skull and skeleton that revealed Mukupirna would have been an herbivore well-suited to digging like wombats, though judging by its size it was probably not a full-blown burrower.

“Mukupirna clearly was an impressive, powerful beast, at least three times larger than modern wombats,” says lead study author Robin Beck, a paleontologist at the University of Salford, in the statement. “It probably lived in an open forest environment without grasses, and developed teeth that would have allowed it to feed on sedges, roots, and tubers that it could have dug up with its powerful front legs.”

While wombats are its closest living relatives, Mukupirna has such unfamiliar features that researchers placed it in its very own, newly created family of marsupials, according to the statement.

“The form of the teeth is unlike any that we've ever seen in any other group of marsupials," Archer tells Anna Salleh of the Australian Broadcasting Corporation. Compared to wombats, Archer tells ABC that Mukupirna had dainty chompers with thin enamel that suggest its diet consisted of softer, more nutritious foliage than the tough grasses favored by wombats today.

The Mukupirna fossil was first collected in 1973 at Australia’s Lake Pinpa, a remote, dried-up salt lake to the east of the Flinders Ranges in South Australia, according to the statement. When researchers started working on it again about ten years ago, they realized it could be something of a missing link within the vombatiforms—an evolutionary group that includes wombats and koalas.

Gavin Prideaux, a palaeontologist from Flinders University who was not involved in the research, tells ABC that while it’s been understood for some time that wombats and koalas are each other's closest living relatives, the substantial differences between them also suggest their evolutionary paths diverged long ago.

Speaking with ABC, Prideaux says Mukupirna could help fill in the evolutionary gap between the two marsupials. "It's got attributes that shows it's very clearly not a wombat, but it's halfway to being a wombat," he says.

Within the extinct vombatiforms, Mukupirna’s big-boned heft wasn’t even particularly unusual. Amy Woodyatt and Rob Picheta of CNN report that the researchers found that members of the group evolved body weights of 220 pounds or more no fewer than six times in the past 25 million years. The very largest one, according to the statement, was a vombatiform named Diprotodon, thundered across the outback weighing more than two metric tons until at least 50,000 years ago.

#News | https://sciencespies.com/news/300-pound-wombat-like-creature-once-roamed-australia/

Exolaunch and NanoAvionics sign contracts for SpaceX flights

SAN FRANCISCO – German launch services provider Exolaunch announced contracts June 29 to integrate NanoAvionics cubesats on SpaceX’s rideshare missions.

Under the agreements, Exolaunch is procuring the launch, handling integration and deploying in orbit two six-unit cubesats built by NanoAvionics, a Lithuanian nanosatellite manufacturer. The first NanoAvionics cubesat covered by the new contract is scheduled to reach orbit on a SpaceX Falcon 9 dedicated rideshare mission in December 2020. The second is schedule for a 2021 SpaceX flight.

“We are glad to be collaborating with Exolaunch on these upcoming satellite launches,” Vytenis Buzas, NanoAvionics CEO and co-founder, said in a statement. “The company is an experienced and trusted partner that responds well to our needs. Not only do they provide deployment systems with a solid flight heritage, but their flexibility towards offering the most suitable launch solutions is extremely valuable to our company and customers.”

Exolaunch announced its first contract in April to send customer satellites on the December 2020 Falcon 9 rideshare flight.

“Exolaunch has numerous international customers who already signed up for this mission,” according to the June 29 news release. “Recently the company extended its contract with SpaceX for an additional ESPA port.” (ESPA is a rocket adapter for secondary payloads.)

“We quickly filled the slots procured on SpaceX’s first dedicated rideshare launch this year,” Exolaunch Commercial Director Jeanne Medvedeva told SpaceNews. “We’ve now started procuring capacity on Falcon 9 rideshare launches in 2021.”

NanoAvionics, a spinoff of Lithuania’s Vilnius University, has established facilities in Vilnius, the United Kingdom and the United States to satisfy growing demand for small satellites.

NanoAvionics is under contract to build five nanosatellites for Sen, a British company planning to stream high-definition video of Earth. A consortium of Norwegian and Dutch research centers hired NanoAvionics to build two nanosatellites for space-based spectrum monitoring. In addition, Thales Alenia Space selected NanoAvionics to manufacture the first two satellite buses for the Omnispace’s internet-of-things constellation.

Exolaunch plans to conduct mechanical testing prior to launching the NanoAvionics cubesats at its Berlin, Germany, headquarters, before integrating the satellites with SpaceX launch vehicles at Florida’s Cape Canaveral. The NanoAvionics satellites will be integrated on a Falcon 9 ESPA port and deployed in orbit using Exolaunch’s EXOpod cubesat deployer, according to the news release.

#Space | https://sciencespies.com/space/exolaunch-and-nanoavionics-sign-contracts-for-spacex-flights/

Astronaut loses a mirror in the middle of a spacewalk - and it's on live stream

Dropping a mirror on Earth is only minor cause for concern, perhaps about the potential of some upcoming bad luck.

Dropping a mirror while on a spacewalk means creating a potentially dangerous new piece of space junk, all while thousands of people watch it happen, streaming live.  

A small mirror came loose from International Space Station Commander Chris Cassidy's spacesuit at the start of a spacewalk on 26 June 2020.

The mirror floated away right after Cassidy emerged from the ISS in orbital darkness to begin a six-hour EVA to upgrade power systems on the station's exterior.

Astronaut spacewalk selfie, 26 June 2020. (NASA)

Spacewalking astronauts have mirrors on each sleeve to get better views while working, since the spacesuit helmets limit the field of view. The mirror is just 5-by-3 inches (7-by-12 centimeters), and according the Associated Press, together with its band has a mass of barely one-tenth of a pound (50 grams).

Cassidy inspected his spacesuit sleeve later while in sunlight but didn't see any clues that might explain why the mirror came off. NASA said later that the lost item posed no risk to either the spacewalk or the ISS.

NASA lists more than 20,000 pieces of debris larger than a softball orbiting the Earth. There are 500,000 pieces of debris the size of a marble or larger and there are many millions of pieces of debris that are so small they can't be tracked.

All these pieces – whether intact satellites or parts of satellites or rockets are traveling at speeds up to 17,500 mph, which is fast enough for even a relatively small piece of orbital debris to damage a satellite or a spacecraft. Tiny paint flecks can damage a spacecraft when traveling at these velocities.

In fact, a number of space shuttle windows needed to be replaced because of damage caused by material that was analyzed and shown to be paint flecks.

"The greatest risk to space missions comes from non-trackable debris," said Nicholas Johnson, NASA chief scientist for orbital debris.

Space junk continues to be a problem without a definite solution. There have been designs for space nets, harpoons or vacuums to gather up small debris.

But some say the most effective way to solve the space junk problem is an international agreement to charge operators "orbital-use fees" for every satellite put into orbit. No word on possible "user fees" for any items lost during a spacewalk.

Astronaut Bob Behnken's ISS battery swapping spacewalk, 26 June 2020. (NASA)

Cassidy and astronaut Bob Behnken conducted the first of four spacewalks to work on upgrading the station's power system. Last Friday, the veteran spacewalkers spent six hours and 7 minutes swapping out five aging nickel-hydrogen (NiH2) batteries with two new lithium-ion (Li-Ion) batteries.

They will go out again on Wednesday, July 1 starting at 7:20 am EDT to swap one more NiH2 battery for a Li-Ion battery on the Starboard-6 truss structure.

This article was originally published by Universe Today. Read the original article.

#Space | https://sciencespies.com/space/astronaut-loses-a-mirror-in-the-middle-of-a-spacewalk-and-its-on-live-stream/

Researchers look for answers as to why western bumblebees are declining

A University of Wyoming researcher and her Ph.D. student have spent the last three years studying the decline of the Western bumblebee. The two have been working with a group of bumblebee experts to fill in gaps of missing information from previous data collected in the western United States. Their goal is to provide information on the Western bumblebee to the U.S. Fish and Wildlife Service while it considers listing this species under the U.S. Endangered Species Act.

"The decline of the Western bumblebee is likely not limited to one culprit but, instead, due to several factors that interact such as pesticides, pathogens, climate change and habitat loss," says Lusha Tronstad, lead invertebrate zoologist with the Wyoming Natural Diversity Database (WYNDD). "Western bumblebees were once the most abundant bumblebees on the West Coast of the U.S., but they are much less frequently observed there now. Pathogens (or parasites) are thought to be a major reason for their decline."

Tronstad and Christy Bell, her Ph.D. student in the Department of Zoology and Physiology, from Laramie, are co-authors of a paper, titled "Western Bumble Bee: Declines in the United States and Range-Wide Information Gaps," that was published online June 26 in Ecosphere, a journal that publishes papers from all subdisciplines of ecological science, as well as interdisciplinary studies relating to ecology.

The two are co-authors because they are members of the Western Bumble Bee Working Group and serve as experts of the Western bumblebee in Wyoming, Tronstad says.

Other contributors to the paper are from the U.S. Geological Survey; U.S. Fish and Wildlife Service; Canadian Wildlife Service; Xerces Society for Invertebrate Conservation in Portland, Ore.; British Columbia Ministry of Environment and Climate Change Strategy; University of Hawaii-Hilo; U.S. Department of Agriculture; The Institute for Bird Populations; University of Vermont; Utah State University; Ohio State University; Denali National Park and Preserve; and the Royal Saskatchewan Museum.

This paper is the result of the Western Bumble Bee Working Group, which is a group of experts on this species who came together to assemble the state of knowledge on this species in the United States and Canada, Tronstad says. The paper shows both what is known and knowledge gaps, specifically in the lack of samples and lack of knowledge about the species. Some prime examples of where spatial gaps in limited sampling exist include most of Alaska, northwestern Canada and the southwestern United States.

"Some areas in the U.S. have less bumblebee sampling in the past and present," Tronstad explains. "This could be for a variety of reasons such as lack of funding for such inventories, lack of bee expertise in that state, etc."

Using occupancy modeling, the probability of detecting the Western bumblebee decreased by 93 percent from 1998-2018, Tronstad says. Occupancy modeling is a complex model that estimates how often the Western bumblebee was detected from sampling events between 1998-2018 in the western United States.

"The data we assembled will be used by the U.S. Fish and Wildlife Service to inform its decision on whether or not to protect the Western bumblebee under the U.S. Endangered Species Act," Tronstad says. "At WYNDD, we collect data, and that data is used by managers. Our mission is to provide the most up-to-date data on which management decisions can be based."

Tronstad says there are several things that homeowners or landowners can do to help this species of bumblebee survive and thrive. These include:

• Plant flowers that bloom throughout the summer. Make sure these flowers have pollen and produce nectar, and are not strictly ornamental.
• Provide a water source for bees. Tronstad says she adds a piece of wood to all of her stock tanks so bees can safely get a drink.
• Provide nesting and overwintering habitat. Most bumblebees nest in the ground, so leaving patches of bare ground covered with litter or small mammal holes will benefit these bees. Be sure not to work these areas until after you see large bumblebees (queen bees) buzzing around in the spring, usually in April for much of Wyoming, so you can find out where they are nesting.

Tronstad says Bell's research will continue this summer, as Bell will investigate pathogens in the Rocky Mountains of Wyoming that affect Western bumblebees there. Max Packebush, a UW sophomore majoring in microbiology and molecular biology, from Littleton, Colo.; and Matt Green, a 2018 UW graduate from Camdenton, Mo., will assist Bell in her research. NASA and the Wyoming Research Scholars Program will fund Packebush to conduct his work. The U.S. Geological Survey and the U.S. Fish and Wildlife Service funded the research for this paper.

Story Source:

Materials provided by University of Wyoming. Note: Content may be edited for style and length.

#Nature | https://sciencespies.com/nature/researchers-look-for-answers-as-to-why-western-bumblebees-are-declining/

An unexpected radiation spike has been detected over Europe

A mysterious increase in radiation levels over northern Europe was detected this month by authorities from several countries, although no nation has yet come forward to claim responsibility for the anomaly.

The subtle radiation spike – at levels that are considered harmless to humans, but significant enough to be picked up by radiation monitoring stations – began to make headlines last week, with European authorities announcing new readings of human-made radionuclide particles in the atmosphere.

"Very low levels of the radioactive substances cesium-134, cesium-137, cobalt-60 and ruthenium-103 were measured," the Swedish Radiation Safety Authority tweeted on Tuesday.

"The levels measured are so low that they pose no danger to people or the environment."

Similar observations were also made by radiation protection authorities in Norway and Finland.

Later in the week, Lassina Zerbo, the Executive Secretary of the Comprehensive Nuclear-Test-Ban Treaty Organisation, tweeted a map outlining the possible source region of the anomaly, most of which was territory inside Russia, but also parts of Finland, Sweden, Denmark, and Norway.

22 /23 June 2020, RN #IMS station SEP63 #Sweden🇸🇪 detected 3isotopes; Cs–134, Cs–137 & Ru–103 associated w/Nuclear fission @ higher[ ] than usual levels (but not harmful for human health). The possible source region in the 72h preceding detection is shown in orange on the map. pic.twitter.com/ZeGsJa21TN

— Lassina Zerbo (@SinaZerbo) June 26, 2020

"These isotopes are most likely from a civil source," Zerbo tweeted, suggesting a source related to nuclear power production, not nuclear weapons.

"We are able to indicate the likely region of the source, but it's outside the CTBTO's [Comprehensive Nuclear-Test-Ban Treaty Organization] mandate to identify the exact origin."

On Friday, the Dutch National Institute for Public Health and the Environment (RIVM) announced that, based on an analysis of the available data, the "combination of radionuclides may be explained by an anomaly in the fuel elements of a nuclear power plant".

On the available evidence, the organisation suggested that the radioactive particles detected had come from the direction of western Russia, but clarified that this did not mean they were definitively linked with Russian power plants.

"Some recent media reports claimed, possibly based on a mistranslation of our original report (in Dutch), that the radionuclides originated from western Russia," RIVM said in a statement.

"The claim RIVM makes is that the radionuclides travelled from the direction of western Russia to Scandinavia, but that no specific country of origin can be pointed out at this moment."

In response to online speculation that Russia was behind the radiation spike, a spokesperson for Rosenergoatom, part of Rosatom state nuclear energy corporation, said the nation's two nuclear power plants in the region were operating normally, with normal radiation levels being reported.

"Both stations are working in normal regime. There have been no complaints about the equipment's work," Rosenergoatom told Russian news agency TASS.

"Aggregated emissions of all specified isotopes in the above-mentioned period did not exceed the reference numbers. No incidents related to release of radionuclide outside containment structures have been reported."

As it stands, it's hard to say whether additional evidence will be able to confirm where this slight radiation surge originated, but the incident recalls a similar situation that took place in 2017, in which another radioactive cloud was detected over Europe.

During that episode – which was also detected at levels harmless to people – many suggested Russian power plants were responsible – a hypothesis that was later supported by scientific findings, although disputed by Rosatom.

#Humans | https://sciencespies.com/humans/an-unexpected-radiation-spike-has-been-detected-over-europe/

A vast garden of soft corals has been discovered off the coast of Greenland

Deep in the cold, dark water, on the seafloor west of Greenland, a quiet ecosystem thrives. For the first time, a garden of soft corals and sponges has been found in these waters, sprawling across an area a little bigger than the City of San Jose.

The discovery highlights not only how little we understand the deeper regions of the ocean, but how much damage we could be doing while unaware. The newly discovered habitat sits right next to a deep-sea trawling area; scientists are calling for it to be classified as a vulnerable marine ecosystem.

Exploring the deep sea is challenging. The deeper you go, the less sunlight penetrates the waters, while the oceanic pressure steadily increases. By the time you're a few hundred metres down, it's cold, it's dark, and the pressure is crushing, at least for humans.

This means that deep-sea exploration requires special high-tech equipment designed to withstand pressure. But the new research shows such exploration can be conducted without a great deal of expense.

The team's rig - which they call a benthic video sled - consists of a GoPro, lights, and laser pointers (set a certain distance apart to act as a scale guide) in pressure cases, housed in a steel frame suspended from their research vessel. This low-cost sled can reach depths of 1,500 metres (4,920 feet).

(Stephen Long)

"The deep sea is often overlooked in terms of exploration. In fact we have better maps of the surface of Mars than we do of the deep sea," said geographer Stephen Long of University College London and the Zoological Society of London in the UK.

"The development of a low-cost tool that can withstand deep-sea environments opens up new possibilities for our understanding and management of marine ecosystems."

It was while using this video sled that the team discovered a vast coral garden spanning 486 square kilometres (188 square miles) in the Mesopelagic zone, at depths between 314 and 585 metres (1,030 and 1,920 feet).

At those depths, very little light penetrates - at the top of the zone, around 200 metres (656 feet) down, only 1 percent of the light visible at the ocean surface remains, and it only gets darker from there. And at 500 metres deep, the pressure is over 50 times the atmospheric pressure at sea level.

Down here, the photosynthetic symbiotic algae that give shallow-water corals their brilliant colours can't survive. But the corals themselves - pale without algae - can still thrive on nutrients in the water.

And this is what the team found: a vast coral garden populated by cauliflower corals, feather stars, sponges, anemones, brittle stars, hydrozoans, bryozoans and, of course, fish.

(ZSL/GINR)

"Coral gardens are characterised by collections of one or more species (typically of non-reef forming coral), that sit on a wide range of hard and soft bottom habitats, from rock to sand, and support a diversity of fauna," explained zoologist Chris Yesson of the Zoological Society of London.

"There is considerable diversity among coral garden communities, which have previously been observed in areas such as northwest and southeast Iceland."

Indeed, there was no shortage of diversity. In 1,239 still images extracted from the GoPro footage, the team annotated 44,035 individual organisms. Of those, anemones were the most abundant at 15,531 identifications, but cauliflower corals weren't far behind, at 11,633 identifications.

That such a vast ecosystem can remain hidden is a reminder for us to consider the environmental impacts of human activity in poorly understood regions of the sea, the researchers said.

"Greenland's seafloor is virtually unexplored, although we know it is inhabited by more than 2,000 different species together contributing to complex and diverse habitats, and to the functioning of the marine ecosystem," said environmental scientist Martin Blicher of the Greenland Institute of Natural Resources.

"Despite knowing so little about these seafloor habitats, the Greenlandic economy depends on a small number of fisheries which trawl the seabed. We hope that studies like this will increase our understanding of ecological relationships, and contribute to sustainable fisheries management."

The research has been published in Frontiers in Marine Science.

#Nature | https://sciencespies.com/nature/a-vast-garden-of-soft-corals-has-been-discovered-off-the-coast-of-greenland/

Analysts: NRO’s commercial imagery purchases could reach $400 million by 2023

A report from Quilty Analytics projects Maxar will retain the bulk of future NRO imagery contracts and emerging competitors Planet and BlackSky will gradually gain market share.

WASHINGTON — The National Reconnaissance Office will increase spending on commercial satellite imagery over the next several years as the agency seeks to benefit from market competition, analysts predict.

A new report from Quilty Analytics estimates the NRO’s annual spending on commercial imagery could grow anywhere from $50 million to $100 million a year. The NRO currently spends about $300 million a year on imagery provided by Maxar under a sole-source contract known as EnhancedView. The combination of purchases under EnhancedView and additional contracts expected to be signed with other vendors could bring total NRO commercial imagery procurements to $400 million a year.

The NRO collects imagery from its own satellites but also acquires products from commercial vendors for use by the intelligence community, the U.S. military and other agencies.

Pete Muend, director of the NRO’s Commercial Systems Program Office, told SpaceNews in a recent interview that the agency plans to award multiple commercial imagery contracts later this year. Muend did not specify how many contracts will be awarded or the expected value of the contracts but he said the NRO will step up purchases from commercial vendors.

“We’re looking at a future where the vast majority of our requirements can be met by commercial providers especially over time as they build up their capabilities,” Muend said.

Justin Cadman, of Quilty Analytics, said Maxar will retain the bulk of future NRO imagery contracts and.emerging competitors Planet and BlackSky will gradually gain market share. Maxar gets about $300 million a year under EnhancedView and its sales to the NRO will likely continue at that level for the next several years. Planet and BlackSky will benefit from the projected growth in annual spending, Cadman said.

The increase is due to the growing needs for satellite imagery by national security agencies, he said. The U.S. withdrawal from the Treaty on Open Skies and an array of global crises also will create new demand for imagery.

Maxar’s EnhancedView contract runs through 2023. Cadman said the NRO is likely to award Planet and BlackSky separate procurement contracts in late 2020 or 2021. After 2023, he said, a new contract vehicle will be developed to replace EnhancedView that will incorporate multiple vendors.

The NRO is looking to tap into the capabilities of a new generation of imaging satellites that deliver high resolution and rapid imagery refresh over key areas of interest.

Cadman said Maxar’s new WorldView Legion constellation will ensure the company will “reap the bulk of contract funding, capturing no less than its current $300 million per year while still providing sizable opportunity for BlackSky and Planet.”

Contract opportunities for these emerging players will “evolve over time, dependent on their success in delivering high-quality data,” said Cadman.

#Space | https://sciencespies.com/space/analysts-nros-commercial-imagery-purchases-could-reach-400-million-by-2023/

How an Alaskan Volcano Is Linked to the Decline of the Roman Republic

The two years after Julius Caesar’s assassination in 44 B.C. were rife with bad luck. The sky turned dark, the weather grew cold, and Mediterranean civilizations experienced drought and famine.

Now, a multidisciplinary team of researchers has pinned down an explosive explanation for these strange occurrences: As detailed in the Proceedings of the National Academy of Sciences, a volcanic eruption some 6,000 miles away from Rome may have thrown off the region’s weather patterns—and perhaps even contributed to the rise of the Roman Empire.

The new study combines evidence from ice cores, tree rings and historical records to identify an eruption of Alaska’s Okmok volcano in 43 B.C. as the cause of unusual weather following the Ides of March, reports Paul Voosen for Science magazine. The enormous eruption triggered an average 13-degree Fahrenheit drop in temperature across southern Europe and northern Africa.

“This is the second coldest year in the last 2,500 years—I mean, that’s not a small thing,” lead author Joe McConnell, a snow hydrologist at the Desert Research Institute in Nevada, tells Atlas Obscura’s Isaac Schultz. “And when you’re talking about an agrarian society that’s living close to the edge as it is, it had to have had a big impact.”

By all accounts, 43 B.C. was a tumultuous year in Roman history. Most of the senators who’d conspired to assassinate Caesar had fled the city. The dead dictator’s grand-nephew and adopted heir, Octavian, had seized power with money and military force. At just 19 years old, he joined the Second Triumvirate, a trio of consuls with dictatorial power. That same year, another member of the Triumvirate, Mark Antony, murdered Cicero, one of the republic’s last defenders.

Cicero’s death is considered the symbolic end of the Roman Republic, according to Science. Letters from the ancient statesman mention the unusually cold weather occurring around the time of the Okmok eruption. In April, northern Italy was struck by famine; Roman biographer Plutarch wrote that Antony’s army was forced to eat wild fruit, roots, bark and animals “never tasted before by men.” In 42 B.C., both northern Greece and Rome suffered similar shortages.

Experts have long suspected that a volcanic eruption was responsible for the extreme weather. But until now, writes Katie Hunt for CNN, researchers had “been unable to pinpoint where or when such an eruption had occurred or how severe it was.”

Arctic ice cores proved key to unraveling the mystery. As Katherine Kornei explains for the New York Times, samples gathered in northern Greenland had high concentrations of sulfur and sulfuric acid in layers corresponding to early 43 B.C. And shards of tephra, or glassy volcanic material, found in the cores matched the chemical makeup of Okmok, allowing the scientists to pinpoint the geological culprit.

“The tiny glass particles in the ice are a clinching piece of evidence,” Siwan Davies, a geographer at Swansea University who wasn’t involved in the study, tells Science.

The Okmok eruption was about the same size as the 1815 eruption of Mount Tambora in Indonesia. This blast sparked the so-called “year without a summer” in Western Europe, according to Atlas Obscura.

Tree ring records in Scandinavia and North America show that 43 and 42 B.C. were cooler than other years. But in the Alps, the cooling trend began ten years prior to the eruption and was actually strongest in 45 B.C.

“If we’re connecting Roman Republican history to climate and volcanoes, we need more of these records,” Kevin Anchukaitis, a paleoclimatologist at the University of Arizona who also wasn’t involved in the study, tells Science.

Other experts point out that the climate model used in the research paper can exaggerate cooling effects from eruptions. Additionally, they argue, extreme weather can’t account for all of the political turmoil that took place as Rome transitioned from a republic to an empire.

“The problems with the republic were political, deep in origin, fought out between members of the elite, not a popular revolution or a subsistence crisis,” Charles University archaeologist Guy Middleton, who was not involved in the study, tells Science.

Unrest persisted long after the physical effects of the volcanic eruption faded. Only after more than a decade of civil war did Octavian emerge as Augustus, emperor of the newly unified Roman Empire. Still, the new paper presents compelling evidence that natural disasters can affect the course of history in unexpected ways.

“It’s not ‘a volcano erupts and a society goes to hell,’” study co-author Joseph Manning, a Yale University historian who studies the fall of Egyptian dynasties, tells the Times. But by unraveling the nuances of past collapses, he says, “We hope in the end that we get better history out of it, but also a better understanding of what’s happening to the Earth right now.”

#News | https://sciencespies.com/news/how-an-alaskan-volcano-is-linked-to-the-decline-of-the-roman-republic/

Mysterious abandonment of once-great Maya city may finally be explained

For over 1,000 years, the ancient Maya city of Tikal stood tall, embodying one of the largest and most important urban centres ever built by this enigmatic and enduring pre-Columbian civilisation.

By the late 9th century CE however, this Maya metropolis was unravelling. Around this time, Tikal and a number of other Maya cities were abandoned, and a new analysis of Tikal's reservoirs lends important new insights into why the city's ancient exodus may have occurred.

A team led by scientists at the University of Cincinnati analysed sediment from reservoirs within the ancient city - located in modern day Guatemala - and found evidence of toxic contaminants that would have made Tikal's drinking water undrinkable.

For a sprawling city prone to severe droughts – and cut off from lakes and rivers – polluted rainwater collectors could have spelt the end for Tikal's thousands of inhabitants, estimated to number up to 100,000 people at the city's peak.

Tikal and its Temple of the Jaguar, as it stands today. (Jimmy Baum/Unsplash)

"The conversion of Tikal's central reservoirs from life-sustaining to sickness-inducing places would have both practically and symbolically helped to bring about the abandonment of this magnificent city," the researchers write in a new paper.

To explore how Tikal's reservoir systems sustained (and failed to sustain) the city's populace, the research team, led by biologist David Lentz, sampled sediment collected from 10 of the city's reservoirs.

Analysis of DNA still contained in the ancient dirt revealed traces of two different kinds of cyanobacteria (blue-green algae) in the reservoirs.

The evidence suggest these organisms – Planktothrix and Microcystis – existed in the reservoirs for centuries during Tikal's occupation, but likely became particularly problematic in blue-green algal blooms during periods of severe dryness just prior to Tikal's abandonment in the mid-9th century CE.

"The water would have looked nasty. It would have tasted nasty," says one of the team, archaeological geologist Kenneth Tankersley.

"There would have been these big blue-green algae blooms. Nobody would have wanted to drink that water."

UC graduate student Brian Lane in the Perdido reservoir. (Nicholas Dunning/UC)

Bugs in the water weren't the only source of toxicity. The analysis also revealed high levels of mercury in the sediment.

After ruling out potential sources of mercury pollution from the natural environment (mercury leaching into water reservoirs from underlying bedrock, or falling onto them via volcanic ash), the researchers realised it was the Maya themselves who likely introduced the contaminant.

"Colour was important in the ancient Maya world," Tankersley says. "They used it in their murals. They painted the plaster red. They used it in burials and combined it with iron oxide to get different shades."

Unfortunately for the Maya, one of the ingredients they used in their paints was the red-coloured mineral cinnabar, which is a form of mercury sulfide, and toxic to humans who come into contact with it.

This toxicity may have been known to the Maya, as it was known by other ancient peoples, but however safely they handled it, they might never have realised that over time, rainwater washed dangerous levels of the toxic pigment from painted surfaces into the city's reservoirs – poisoning even the city's elite, who lived near Tikal's Palace and Temple reservoirs.

"As a result, the leading families of Tikal likely were fed foods laced with mercury at every meal," the authors explain.

"Contaminated waters would have had a negative impact on the health of the community, especially the ruling elite, and may have compromised their ability to lead effectively."

A model revealing Tikal's layout in ancient times. (Nicholas Dunning/UC)

In the same time period, climatic aridification and environmental degradation were also huge problems for the Maya, but the lack of fresh drinking water – a potent symbol in the culture – may have been the final straw in a drought-stricken, polluted city on the verge of collapse.

"There may well have been those who saw the events described above and the concomitant droughts as a failure of their leaders to adequately appease the Maya gods," the researchers write.

"Indeed, these events coming together must have resulted in a demoralised populace who, in the face of dwindling water and food supplies, became more willing to abandon their homes."

The findings are reported in Scientific Reports.

#Humans | https://sciencespies.com/humans/mysterious-abandonment-of-once-great-maya-city-may-finally-be-explained/

Neptune rains diamonds, and now we might finally know how

Deep within the hearts of Neptune and Uranus, it could be raining diamonds. Now, scientists have produced new experimental evidence showing how this could be possible.

The hypothesis goes that the intense heat and pressure thousands of kilometres below the surface of these ice giants should split apart hydrocarbon compounds, with the carbon compressing into diamond and sinking even deeper towards the planetary cores.

The new experiment used the SLAC National Accelerator Laboratory's Linac Coherent Light Source (LCLS) X-ray laser for the most precise measurements yet of how this 'diamond rain' process should occur - and found that carbon transitions directly into crystalline diamond.

"This research provides data on a phenomenon that is very difficult to model computationally: the 'miscibility' of two elements, or how they combine when mixed," explained plasma physicist Mike Dunne, director of the LCLS, and not listed as an author on the paper.

"Here they see how two elements separate, like getting mayonnaise to separate back into oil and vinegar."

Neptune and Uranus are the most poorly understood planets in the Solar System. They are prohibitively far - only a single space probe, Voyager 2, has even been close to them, and only for a flyby, not a dedicated long-term mission.

But ice giants are extremely common in the broader Milky Way - according to NASA, Neptune-like exoplanets are 10 times more prevalent than Jupiter-like exoplanets.

Understanding our Solar System's ice giants, therefore, is vital to understanding planets throughout the galaxy. And to understand them better, we need to know what happens underneath their serene blue exteriors.

We know that the atmospheres of Neptune and Uranus are primarily made up of hydrogen and helium, with a small amount of methane. Below these atmospheric layers, a superhot, superdense fluid of 'icy' materials such as water, methane, and ammonia wraps around the planet's core.

And calculations and experiments dating back decades have shown that, with sufficient pressure and temperature, methane can be broken down into diamonds - suggesting that diamonds can form within this hot, dense material.

A previous experiment at SLAC led by physicist Dominik Kraus at the Helmholtz-Zentrum Dresden-Rossendorf in Germany used X-ray diffraction to demonstrate it. Now Kraus and his team have taken their research a step further.

"We now have a very promising new approach based on X-ray scattering," Kraus said about their latest efforts. "Our experiments are delivering important model parameters where, before, we only had massive uncertainty. This will become ever more relevant the more exoplanets we discover."

It's challenging to replicate the interiors of giant planets here on Earth. You need some pretty intense equipment - that's the LCLS. And you need a material that replicates the stuff inside that giant planet. For this, the team used the hydrocarbon polystyrene (C₈H₈) in place of methane (CH₄).

The first step is to heat and pressurise the material to replicate the conditions inside Neptune at a depth of around 10,000 kilometres (6,214 miles): pulses of optical laser generate shockwaves in the polystyrene, which heats the material up to around 5,000 Kelvin (4,727 degrees Celsius, or 8,540 degrees Fahrenheit). It also creates intense pressure.

"We produce about 1.5 million bars, that is equivalent to the pressure exerted by the weight of some 250 African elephants on the surface of a thumbnail," Kraus said.

In the previous experiment, X-ray diffraction was used to then probe the material. This works well for materials with crystalline structures, but less so with non-crystalline molecules, so the picture was incomplete. In the new experiment, the team used a different method, measuring how X-rays scattered off electrons in the polystyrene.

This allowed them not just to observe the conversion of carbon into diamond, but also what happens to the rest of the sample - it splits off into hydrogen. And there's pretty much no leftover carbon.

"In the case of the ice giants we now know that the carbon almost exclusively forms diamonds when it separates and does not take on a fluid transitional form," Kraus said.

This is important, because there's something really weird about Neptune. Its interior is way hotter than it should be; in fact, it gives off 2.6 times more energy than it absorbs from the Sun.

If diamonds - more dense than the material around them - are raining down into the planet's interior, they could be releasing gravitational energy, which is converted into heat generated by friction between the diamonds and the material around them.

This experiment suggests we don't have to find an alternative explanation… not yet, at any rate. And it also shows a method we could use to 'probe' the interiors of other planets in the Solar System.

"This technique will allow us to measure interesting processes that are otherwise difficult to recreate," Kraus said.

"For example, we'll be able to see how hydrogen and helium, elements found in the interior of gas giants like Jupiter and Saturn, mix and separate under these extreme conditions. It's a new way to study the evolutionary history of planets and planetary systems, as well as supporting experiments towards potential future forms of energy from fusion."

The research has been published in Nature Communications.

#Nature | https://sciencespies.com/nature/neptune-rains-diamonds-and-now-we-might-finally-know-how/