Impact of a second Dust Bowl would be felt worldwide

by Frontiers

Credit: CC0 Public Domain

The American Dust Bowl of the 1930s—captured by the novels of John Steinbeck—was an environmental and socio-economic disaster that worsened the Great Depression.

The Dust Bowl was an extreme event. But due to climate change, massive crop failures are more likely to happen again in the future. New research in Frontiers in Sustainable Food Systems aimed to answer what these impacts may look like.

The Dust Bowl was centered on the Great Plains of the USA, where decades of unsustainable deep plowing had displaced native, moisture-retaining grasses. An atypical La Niña then brought intense droughts, high temperatures, and strong winds which blew away the topsoil in the form of large-scale dust storms.

Apart from its direct impact on people (around 7,000 deaths and two million homeless), the Dust Bowl had a catastrophic effect on crops where wheat and maize production in the USA plummeted by 36% and 48% during the 1930s.

Currently, the Intergovernmental Panel on Climate Change predicts that in another three to four decades that most of the USA will have further warmed by 1.5-2 °C. This compounds issues that already exist today, where global food security is under pressure from the increased frequency of extreme weather events.

"We wanted to forecast how a multi-year production decline in a major exporting country, similar to that which occurred during the Dust Bowl, would affect modern food supplies globally via international trade," says first author Dr. Alison Heslin, a postdoctoral researcher at the Center for Climate Systems Research of Columbia University and NASA's Goddard Institute for Space Studies.

"In today's system of global food trade, disruptions are not bound by borders. Shocks to production are expected to affect trade partners who depend on imports for their domestic food supply."

To assess the possible impacts of a second dust bowl, the authors first developed two alternative computer simulations of the worldwide trade in wheat. They then delivered a shock to these model systems in the form of a four-year-long Dust Bowl-like anomaly, restricted to the USA.

Under one simulation, countries first use their reserves and then divide the absorbed shock between imports and exports, propagating it in one direction by increasing imports and in another by decreasing exports.

Under the more complicated second model, the USA first reduces only its exports, propagating the shock to all receiving trade partners, after which all countries with a shortage respond by increasing their imports.

Their results predict a severity similar to that of the original event, estimated from historical data. The results show that the USA would fully exhaust 94% of its reserves over the first four years of a Dust Bowl-liked agricultural shock.

They also show that without exception, all countries to which the USA exports wheat would decrease their reserves, even though they didn't themselves suffer crop failure.

"We focused on a subset of the possible impacts, specifically changes in trade, drawing down strategic reserves and decreases in consumption," says co-author Dr. Jessica Gephart, Assistant Professor at the Department of Environmental Science of the American University in Washington DC.

"We found that global wheat trade contracts and shifts toward other wheat exporters, and that wheat reserves around the world decline, in many cases to zero. This suggests that the impacts would not only raise prices for US consumers but would also raise prices far beyond the US borders," says Gephart.

Key impacts of another four-year dust bowl could include an initial 31% loss of global wheat stocks, and by the end of the four years, between 36-52 countries could have used up over 75% of their starting reserves. The 10 countries with the highest initial reserves (China, USA, India, Iran, Canada, Russia, Morocco, Australia, Egypt, Algeria) would see their reserves decline by 15-22 % relative to the starting points.

However, a silver lining is that due to the high initial starting point of global reserves, most supply shocks, even in countries without reserves, could be addressed through trade flow adjustments without reducing consumption.

"Our results remind us that mitigating climate risks requires accounting for not only the direct effects of climate change, like local extreme weather events, but also the climate impacts which travel through our interconnected system of global trade."

"In the context of food security, we show that accessing food reserves can, for a time, buffer populations from trade-induced supply shortages but as reserves deplete, people are at risk of food shortages," says Heslin.

Climate change and the threat to global breadbaskets

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More information: Frontiers in Sustainable Food Systems, DOI: 10.3389/fsufs.2020.00026 , https://www.frontiersin.org/articles/10.3389/fsufs.2020.00026/full

Hidden source of carbon found at the Arctic coast

by University of Texas at Austin 

Credit: CC0 Public Domain

A previously unknown significant source of carbon just discovered in the Arctic has scientists marveling at a once overlooked contributor to local coastal ecosystems—and concerned about what it may mean in an era of climate change.

In a Nature Communications paper released today, aquatic chemists and hydrologists from The University of Texas at Austin's Marine Science Institute and Jackson School of Geosciences, U.S. Fish and Wildlife Service and Florida State University present evidence of significant, undetected concentrations and fluxes of dissolved organic matter entering Arctic coastal waters, with the source being groundwater flow atop of frozen permafrost. This water moves from land to sea unseen, but researchers now believe it carries significant concentrations of carbon and other nutrients to Arctic coastal food webs.

Groundwater is known globally to be important for delivering carbon and other nutrients to oceans, but in the Arctic, where much water remains trapped in frozen earth, its role has been less clear. Scientists were surprised to learn that groundwater may be contributing an amount of dissolved organic matter to the Alaskan Beaufort Sea that is almost on a par with what comes from neighboring rivers during the summer.

"We have to start thinking differently about groundwater," said senior author Jim McClelland, professor of marine sciences at UT Austin. "The water that flows from rivers to the Arctic Ocean is pretty well accounted for, but until now the groundwater flowing to this ocean hasn't been."

The research community has generally assumed that groundwater inputs from land to sea are small in the Arctic because perennially frozen ground, or permafrost, constrains the flow of water below the tundra surface.

The research published today describes sampling the concentration and age of dissolved carbon, as well as nitrogen, in groundwater flowing beneath the land's surface in the Arctic during the summer. The team found that as shallow groundwater flows beneath the surface at sites in northern Alaska, it picks up new, young organic carbon and nitrogen as expected. However, they also discovered that as groundwater flows toward the ocean, it mixes with layers of deeper soils and thawing permafrost, picking up and transporting century-to-millennia old organic carbon and nitrogen.

This old carbon being transported by groundwater is thought to be minimally decomposed, never having seen the light of day before it meets the ocean.

"Groundwater inputs are unique because this material is a direct shot to the ocean without seeing or being photodegraded by light," McClelland said. "Sunlight on the water can decompose organic carbon as it travels downstream in rivers. Organic matter delivered to the coastal ocean in groundwater is not subject to this process, and thus may be valuable as a food source to bacteria and higher organisms that live in Arctic coastal waters."

The researchers concluded that the supply of leachable organic carbon from groundwater amounts to as much as 70% of the dissolved organic matter flux from rivers to the Alaska Beaufort Sea during the summer.

"Despite its ancient age, dissolved organic carbon in groundwater provides a new and potentially important source of fuel and energy for local coastal food webs each summer," said lead author Craig Connolly, a recent graduate of UT Austin's Marine Science Institute. "The role that groundwater inputs play in carbon and nutrient cycling in Arctic coastal ecosystems, now and in the future as climate changes and permafrost continues to thaw, is something we hope will spark research interest for years to come."

Co-author M. Bayani Cardenas, a professor in the Jackson School of Geosciences, said that climate change's outsized effect on the Arctic makes groundwater research all the more important.

"The Arctic is heating up twice as much as the rest of the planet. With that comes permafrost thawing and the birth of aquifers," he said. "It is likely that groundwater transport in the Arctic will be more and more important in the future."

Fresh groundwater flow important for coastal ecosystems

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More information: Nature Communications (2020). DOI: 10.1038/s41467-020-15250-8

Geologists find lost fragment of ancient continent in Canada's North
by University of British Columbia

Geologists studying rock samples from Baffin Island find lost fragment of continent. Credit: istock

Sifting through diamond exploration samples from Baffin Island, Canadian scientists have identified a new remnant of the North Atlantic craton—an ancient part of Earth's continental crust.

A chance discovery by geologists poring over diamond exploration samples has led to a major scientific payoff.

Kimberlite rock samples are a mainstay of diamond exploration. Formed millions of years ago at depths of 150 to 400 kilometers, kimberlites are brought to the surface by geological and chemical forces. Sometimes, the igneous rocks carry diamonds embedded within them.

"For researchers, kimberlites are subterranean rockets that pick up passengers on their way to the surface," explains University of British Columbia geologist Maya Kopylova. "The passengers are solid chunks of wall rocks that carry a wealth of details on conditions far beneath the surface of our planet over time."

But when Kopylova and colleagues began analyzing samples from a De Beers Chidliak Kimberlite Province property in southern Baffin Island, it became clear the wall rocks were very special. They bore a mineral signature that matched other portions of the North Atlantic craton—an ancient part of Earth's continental crust that stretches from Scotland to Labrador.

"The mineral composition of other portions of the North Atlantic craton is so unique there was no mistaking it," says Kopylova, lead author of a new paper in the Journal of Petrology that outlines the findings. "It was easy to tie the pieces together. Adjacent ancient cratons in Northern Canada—in Northern Quebec, Northern Ontario and in Nunavut—have completely different mineralogies."

Cratons are billion-year old, stable fragments of continental crust—continental nuclei that anchor and gather other continental blocks around them. Some of these nuclei are still present at the center of existing continental plates like the North American plate, but other ancient continents have split into smaller fragments and been re-arranged by a long history of plate movements.

"Finding these 'lost' pieces is like finding a missing piece of a puzzle," says Kopylova. "The scientific puzzle of the ancient Earth can't be complete without all of the pieces."

The continental plate of the North Atlantic craton rifted into fragments 150 million years ago, and currently stretches from northern Scotland, through the southern part of Greenland and continues southwest into Labrador.

The newly identified fragment covers the diamond bearing Chidliak kimberlite province in southern Baffin Island. It adds roughly 10 percent to the known expanse of the North Atlantic craton.

This is the first time geologists have been able to piece parts of the puzzle together at such depth—so called mantle correlation. Previous reconstructions of the size and location of Earth's plates have been based on relatively shallow rock samples in the crust, formed at depths of one to 10 kilometers.

"With these samples we're able to reconstruct the shapes of ancient continents based on deeper, mantle rocks," says Kopylova. "We can now understand and map not only the uppermost skinny layer of Earth that makes up one percent of the planet's volume, but our knowledge is literally and symbolically deeper. We can put together 200-kilometer deep fragments and contrast them based on the details of the deep mineralogy."

The samples from the Chidliak Kimberlite Province in southern Baffin Island were initially provided by Peregrine Diamonds, a junior exploration company. Peregrine was acquired by the international diamond exploration company and retailer De Beers in 2018. The drill cores sample themselves are very valuable, and expensive to retrieve.

"Our partner companies demonstrate a lot of goodwill by providing research samples to UBC, which enables fundamental research and the training of many grad students," says Kopylova. "In turn, UBC research provides the company with information about the deep diamondiferous mantle that is central to mapping the part of the craton with the higher changes to support a successful diamond mine."Hidden past of Earth's oldest continents unearthed

More information: M G Kopylova et al. The metasomatized mantle beneath the North Atlantic Craton: Insights from peridotite xenoliths of the Chidliak kimberlite province (NE Canada), Journal of Petrology (2019). DOI: 10.1093/petrology/egz061

Geologists find a lost fragment of an ancient continent filled with diamonds that formed part of Earth's 

continental crust 2.7 billion years ago in Canada's North Atlantic

Scientists find a diamond-filled hunk of the 2.7B-year-old North Atlantic Craton

The NAC forms part of the Earth's ancient crust that is now deep underground 

The sample at a depth of more than 100 miles helps reconstruct Earth's geology

By JONATHAN CHADWICK FOR MAILONLINE  20 March 2020

Diamond-encrusted rock samples that have been found on a Canadian island fill ‘a piece in the puzzle’ to reconstruct an ancient part of Earth's continental crust.

A fragment of the North Atlantic Craton (NAC) was found by geologists who were sifting through diamond exploration samples from the southern Baffin Island, Canada.
The NAC is an ancient part of Earth’s continental crust that reaches around the top of the northern hemisphere, from Scotland to the Canadian region of Labrador, deep underground.

Researchers believe the NAC is up to 2.7 billion years old before its continental plate broke up around 150 million years ago.

Evidence of the ancient crust – which has previously been found in Scotland, Greenland and Labrador – is much sought after.

The new sample of kimberlite, a type of igneous rock, showed unmistakable properties similar to other portions of the NAC, the researchers said.

The University of British Columbia researchers say the rock samples from Canada's Baffin Island (pictured) are like 'a missing piece of a puzzle'

The rock is from the North Atlantic Craton - an ancient part of the Earth's continental crust, now deep underground, that stretches from the southern tip of Baffin Island to the very north of Scotland

The fragment adds about 10 percent to the known expanse of the NAC and also helps reconstruct mysterious shapes of Earth’s ancient continental crust.

WHAT IS KIMBERLITE?

Kimberlite is a dark-coloured, heavy fragmented rock that contains diamonds.

It often has rounded crystals surrounded by a fine-grained matrix of groundmass.

It is a type of igneous rock - rock that is formed through the cooling and solidification of magma or lava.

It's named after the town of Kimberley in South Africa, where the discovery of an 83.5-carat diamond called in 1869 spawned a diamond rush.

Kimberlite is still sought after and drives multi-million dollar mining operations.

‘The mineral composition of other portions of the North Atlantic Craton is so unique there was no mistaking it,’ said University of British Columbia geologist Maya Kopylova.

‘It was easy to tie the pieces together. Adjacent ancient cratons in northern Canada – in northern Qubec, northern Ontario and Nunavut – have completely different mineralogies.’

‘Finding these “lost” pieces is like finding a missing piece of a puzzle.'

The NAC was present as a single continent before it split into many fragments by emerging seas and oceans, Professor Kopylova told MailOnline, and the same process is now splitting the Arabian peninisula from East Africa.

Kimberlite rock samples – which are not just located in Canada – are described as a mainstay of diamond exploration.

They were formed millions of years ago at depths of 90 to 640 miles (150 to 400 kilometres).

These igneous rocks were brought to the surface by geological and chemical forces, sometimes with diamonds embedded in them.

The new ‘diamondiferous’ – or diamond-bearing – fragment covers Baffin Island’s Chidliak kimberlite province.

The Chidliak mining project, approximately 120 km northeast of Iqaluit, the capital of Nunavut territory, is now owned by diamond retail giant De Beers.

‘For researchers, kimberlites are subterranean rockets that pick up passengers on their way to the surface,’ said Professor Kopylova.

‘The passengers are solid chunks of wall rocks that carry a wealth of details on conditions far beneath the surface of our planet over time.’

An example of kimberlite, an igneous rock that contain diamonds. As well as being valuable to diamond retailers, kimberlite rock samples can help reconstruct the shapes of ancient continents

Previous reconstructions of the size and location of Earth’s plates have been based on fairly shallow rock samples in the crust that were formed at depths of about 0.5 to six miles.

‘With these samples we’re able to reconstruct the shapes of ancient continents based on deeper, mantle rocks,’ she said.

‘We can now understand and map not only the uppermost skinny layer of Earth that makes up one per cent of the planet’s volume, but our knowledge is literally and symbolically deeper.'

The samples were provided by Peregrine Diamonds, a Canada-based mineral exploration company, which was acquired by De Beers in 2018.


De Beers Canada acquired the Chidliak Project in September 2018 as part of the purchase of Peregrine Diamonds Ltd

Professor Kopylova said that the samples are now loaned out to the University of British Columbia by the company for research purposes.

‘In turn, UBC research provides the company with information about the deep diamondiferous mantle that is central to mapping the part of the craton with the higher changes to support a successful diamond mine.’

The findings have been detailed in the Journal of Petrology.

WHAT ARE CRATONS?

Cratons are the mantle underlying the oldest portions of the Earth, and establishing their composition and structure has been called one of the greatest challenges to earth sciences.

They’re stable fragments of continental crust – ‘nuceli’ that anchors and gathers other continental blocks around them.

Some of these nuclei are still present at the centre of existing continental plates, but other ancient continents have been split into smaller fragments and rearranged by plate movements.

‘The scientific puzzle of the ancient Earth ‘can’t be complete without all of the pieces’, said Professor Kopylova.

The continental plate of the North Atlantic Craton tore apart into fragments 150 million years ago and currently stretches from northern Scotland to the southern part of Greenland and southwest into Labrador.

Read more: metasomatized mantle beneath the North Atlantic Craton: Insights from peridotite xenoliths of the Chidliak kimberlite province (NE Canada) | Journal of Petrology | Oxford Academic

Initial findings of artificial impact on asteroid Ryugu

by Bob Yirka , Phys.org

Credit: JAXA

A large team of researchers affiliated with multiple institutions across Japan has revealed the age of the asteroid Ryugu and other characteristics by firing a copper ball at its surface. In their paper published in the journal Science, the group describes what they have learned so far from their attempt to mimic the conditions in which craters form.


Back in 2014, Japan's JAXA space agency launched the space probe Hayabusa2—its mission was to travel to the asteroid Ryugu and learn more about it. The probe arrived at the asteroid two years ago and began its surveying mission. One of its tasks involved firing a 2-kilogram copper ball at the asteroid at 7,200 km/h. The goal was to learn more about how craters form and to learn more about the structure of Ryugu. The tennis-ball sized projectile blasted a crater onto the surface of the asteroid 14.5 meters wide and 2.3 meters deep. It also generated a brief debris cloud. In analyzing the material in the debris cloud and in the bottom and sides of the craters, the researchers have been able to learn more about the makeup of the asteroid.

The researchers found sand-like material under the rocky surface, adding credence to theories that have suggested Ryugu is a "rubble pile" type of asteroid, formed from the materials left over when a larger body is destroyed by a collision with another body. The researchers also noted that the crater was not round, but was instead more crescent-shaped, suggesting that one of its edges abuts a very large underground rock that was hard enough to avoid being fractured by the projectile.



PlayEjecta curtain growth and deposition on Ryugu. Credit: JAXA, Kobe University, Chiba Institute of Technology, Kochi University, University of Occupational and Environmental Health

The finding of sand-like material also suggests the asteroid is likely much younger than some had speculated prior to the Hayabusa2 mission. The researchers now believe it to be approximately 9 million years old. The team also noted that the formation of the crater was limited by gravity, not surface strength, again suggesting that the asteroid is made of fragile, porous material. They pointed out that the crater created by the projectile was approximately seven times bigger than it would have been on Earth, which has a much harder surface.


Explore furtherJapan spacecraft releases rover to asteroid in last mission
More information: M. Arakawa et al. An artificial impact on the asteroid 162173 Ryugu formed a crater in the gravity-dominated regime, Science (2020). DOI: 10.1126/science.aaz1701
Journal information: Science



© 2020 Science X Network

Epigenetic inheritance: A 'silver bullet' against climate change?

by Helmholtz Association of German Research Centres

Three-spined sticklebacks are used as model organisms in this study. Credit: M. Heckwolf, GEOMAR

The current pace of climate change exceeds historical events by 1-2 orders of magnitude, which will make it hard for organisms and ecosystems to adapt. For a long time, it has been assumed that adaptation was only possible by changes in the genetic makeup—the DNA base sequence. Recently, another information level of DNA, namely epigenetics, has come into focus.

Using a fish species from the Baltic Sea, the three-spined stickleback, an international team investigated whether and how epigenetics contributes to adaptation. "Our experiment shows that epigenetic modifications affect adaptation, but also that the changes from one generation to the next are smaller than previously assumed," says biologist Dr. Melanie Heckwolf from GEOMAR Helmholtz Centre for Ocean Research Kiel. She is one author of the study, which has now been published in Science Advances.

But what distinguishes changes in DNA from changes in epigenetics? "Individuals with certain heritable traits encoded in DNA can cope with the prevailing environment better than others. On average, those individuals can cope better with their environment, hence survive longer and produce more offspring. In the long run, their characteristics encoded in the DNA will prevail. This process refers to natural selection," explains Dr. Britta Meyer from GEOMAR. However, selection requires time, and time is scarce in the face of rapid climate change.

In contrast, epigenetic processes chemically influence the structure of DNA. They activate or deactivate areas of the genome that are responsible for certain traits or responses to environmental conditions. On the one hand, 'stable' epigenetic markers, through natural selection, contribute to adaptation in a similar way as the DNA itself. On the other hand, 'inducible' markers are those that can change during the life of an individual. In theory, if this happens in the gametes of parents, their offspring are given an advantage to cope with their environment. Many scientists therefore expect that inducible markers will react particularly quickly and thus ensure the survival of organisms in the face of rapid changes.

The research groups of Prof. Dr. Thorsten Reusch (GEOMAR, Germany) and Dr. Christophe Eizaguirre (Queen Mary University of London, UK) have investigated whether and how these stable and inducible markers contribute to adaptation. They use the Baltic three-spined stickleback fish because it is currently adapted to different salinity conditions ranging from saltwater to freshwater. Further, the Baltic Sea is a natural laboratory for climate change research because the effects of climate change are already evident there.

"In order to understand how fish respond to the consequences of climate change, we collected stickleback populations from different regions of the North and Baltic Seas with different salinity levels," explains Dr. Meyer. The team found that the different populations differed in their genetic and epigenetic makeups and also had different tolerances to changes in salinity. In an experiment involving two generations of sticklebacks, the team was also able to show that inducible markers improve the response of the second generation to environmental change, albeit to a lesser extent than initially assumed.

Overall, the study shows that organisms will eventually reach their limits to respond to climate change, even with epigenetic modes of adaptation. "We have to be careful not to overinterpret this exciting but poorly understood field of research in epigenetics as a silver bullet against climate change for all species," says Melanie Heckwolf. "Climate change is one of the greatest challenges for species and ecosystems, and the natural mechanisms available to species to respond may not be sufficient if climate change remains so strong and rapid."

Researchers find new method to allow corals to rapidly respond to climate change
More information: "Two different epigenetic information channels in wild three-spined sticklebacks are involved in salinity adaptation" Science Advances (2020). DOI: 10.1126/sciadv.aaz1138 , https://advances.sciencemag.org/content/6/12/eaaz1138

Curiosity Mars rover takes a new selfie before record climb

by Andrew Good, Jet Propulsion Laboratory

This selfie was taken by NASA's Curiosity Mars rover on Feb. 26, 2020 (the 2,687th Martian day, or sol, of the mission). The crumbling rock layer at the top of the image is "the Greenheugh Pediment," which Curiosity climbed soon after taking the image. Credit: NASA/JPL-Caltech/MSSS 

NASA's Curiosity Mars rover recently set a record for the steepest terrain it's ever climbed, cresting the "Greenheugh Pediment," a broad sheet of rock that sits atop a hill. And before doing that, the rover took a selfie, capturing the scene just below Greenheugh.

In front of the rover is a hole it drilled while sampling a bedrock target called "Hutton." The entire selfie is a 360-degree panorama stitched together from 86 images relayed to Earth. The selfie captures the rover about 11 feet (3.4 meters) below the point where it climbed onto the crumbling pediment.

Curiosity finally reached the top of the slope March 6 (the 2,696th Martian day, or sol, of the mission). It took three drives to scale the hill, the second of which tilted the rover 31 degrees—the most the rover has ever tilted on Mars and just shy of the now-inactive Opportunity rover's 32-degree tilt record, set in 2016. Curiosity took the selfie on Feb. 26, 2020 (Sol 2687).

Since 2014, Curiosity has been rolling up Mount Sharp, a 3-mile-tall (5-kilometer-tall) mountain at the center of Gale Crater. Rover operators at NASA's Jet Propulsion Laboratory in Southern California carefully map out each drive to make sure Curiosity will be safe. The rover is never in danger of tilting so much that it would flip over—Curiosity's rocker-bogie wheel system enables it to tilt up to 45 degrees safely—but the steep drives do cause the wheels to spin in place.

This video shows how the robotic arm on NASA's Curiosity Mars rover moves as it takes a selfie. Credit: NASA/JPL-Caltech

How Are Selfies Taken?

Before the climb, Curiosity used the black-and-white Navigation Cameras located on its mast to, for the first time, record a short movie of its "selfie stick," otherwise known as its robotic arm.

Curiosity's mission is to study whether the Martian environment could have supported microbial life billions of years ago. One tool for doing that is the Mars Hand Lens Camera, or MAHLI, located in the turret at the end of the robotic arm. This camera provides a close-up view of sand grains and rock textures, similarly to how a geologist uses a handheld magnifying glass for a closer look in the field on Earth.

In this video, JPL imaging specialist Justin Maki explains how NASA's Mars Curiosity rover takes a selfie. Credit: NASA/JPL-Caltech

By rotating the turret to face the rover, the team can use MAHLI to show Curiosity. Because each MAHLI image covers only a small area, it requires many images and arm positions to fully capture the rover and its surroundings.

"We get asked so often how Curiosity takes a selfie," said Doug Ellison, a Curiosity camera operator at JPL. "We thought the best way to explain it would be to let the rover show everyone from its own point of view just how it's done.Curiosity Mars rover snaps its highest-resolution panorama yet

Asteroid Ryugu likely link in planetary formation

by Falk Dambowsky, German Aerospace Center

Close-up of Asteroid Ryugu. Credit: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu, AIST, Kobe University, Auburn University

The solar system formed approximately 4.5 billion years ago. Numerous fragments that bear witness to this early era orbit the sun as asteroids. Around three-quarters of these are carbon-rich C-type asteroids, such as 162173 Ryugu, which was the target of the Japanese Hayabusa2 mission in 2018 and 2019. The spacecraft is currently on its return flight to Earth. Many scientists, including planetary researchers from the German Aerospace Center (Deutsches Zentrum für Luft-und Raumfahrt; DLR), intensively studied this cosmic "rubble pile," which is almost 1 kilometer in diameter and can come close to Earth. Infrared images acquired by Hayabusa2 have now been published in the scientific journal Nature. They show that the asteroid consists almost entirely of highly porous material. Ryugu was formed largely from fragments of a parent body that was shattered by impacts. The high porosity and the associated low mechanical strength of the rock fragments that make up Ryugu ensure that such bodies break apart into numerous fragments upon entering Earth's atmosphere. For this reason, carbon-rich meteorites are very rarely found on Earth and the atmosphere tends to offer greater protection against them.

Thermal behavior reveals density

This investigation of the global properties of Ryugu confirms and complements the findings of the landing environment on Ryugu obtained by the German-French Mobile Asteroid Surface SCOuT (MASCOT) lander during the Hayabusa2 mission. "Fragile, highly porous asteroids like Ryugu are probably the link in the evolution of cosmic dust into massive celestial bodies," says Matthias Grott from the DLR Institute of Planetary Research, one of the authors of the current Nature publication. "This closes a gap in our understanding of planetary formation, as we have hardly ever been able to detect such material in meteorites found on Earth."

In autumn 2018, the scientists working with first author Tatsuaki Okada of the Japanese space agency JAXA analyzed the asteroid's surface temperature in several series of measurements performed with the Thermal Infrared Imager (TIR) on board Hayabusa2. These measurements were made in the 8 to 12 micrometer wavelength range during day and night cycles. In the process, they discovered that, with very few exceptions, the surface heats up very quickly when exposed to sunlight. "The rapid warming after sunrise, from approximately minus 43 degrees Celsius to plus 27 degrees Celsius suggests that the constituent pieces of the asteroid have both low density and high porosity," explains Grott. About 1% of the boulders on the surface were colder and more similar to the meteorites found on Earth. "These could be more massive fragments from the interior of an original parent body, or they may have come from other sources and fallen onto Ryugu," adds Jörn Helbert from the DLR Institute of Planetary Research, who is also an author of the current Nature publication.

Temperature measurements on Ryugu's surface. Credit: MASCOT/DLR/JAXA

From planetesimals to planets

The fragile porous structure of C-type asteroids might be similar to that of planetesimals, which formed in the primordial solar nebula and accreted during numerous collisions to form planets. Most of the collapsing mass of the pre-solar cloud of gas and dust accumulated in the young sun. When a critical mass was reached, the heat-generating process of nuclear fusion began in its core.

The remaining dust, ice and gas accumulated in a rotating accretion disk around the newly formed star. Through the effects of gravity, the first planetary embryos or planetesimals were formed in this disc approximately 4.5 billion years ago. The planets and their moons formed from these planetesimals after a comparatively short period of perhaps only 10 million years. Many minor bodies—asteroids and comets—remained. These were unable to agglomerate to form additional planets due to gravitational disturbances, particularly those caused by Jupiter—by far the largest and most massive planet.

However, the processes that took place during the early history of the solar system are not yet fully understood. Many theories are based on models and have not yet been confirmed by observations, partly because traces from these early times are rare. "Research on the subject is therefore primarily dependent on extraterrestrial matter, which reaches Earth from the depths of the solar system in the form of meteorites," explains Helbert. It contains components from the time when the sun and planets were formed. "In addition, we need missions such as Hayabusa2 to visit the minor bodies that formed during the early stages of the solar system in order to confirm, supplement or—with appropriate observations—refute the models."

MASCOT radiometer MARA. Credit: DLR (CC-BY 3.0)

A rock like many on Ryugu

In the summer of 2019, results from the MASCOT lander mission showed that its landing site on Ryugu was mainly populated by large, highly porous and fragile boulders. "The published results are a confirmation of the results from the studies by the DLR radiometer MARA on MASCOT," said Matthias Grott, the Principal Investigator for MARA. "It has now been shown that the rock analysed by MARA is typical for the entire surface of the asteroid. This also confirms that fragments of the common C-type asteroids like Ryugu probably break up easily due to low internal strength when entering Earth's atmosphere."

On 3 October 2018, MASCOT landed on Ryugu in free fall at walking pace. Upon touchdown, it "bounced" several meters further before the approximately 10-kilogram experiment package came to a halt. MASCOT moved on the surface with the help of a rotating swing arm. This made it possible to turn MASCOT on its "right" side, and even perform jumps on the asteroid's surface due to Ryugu's low gravitational attraction. In total, MASCOT performed experiments on Ryugu for approximately 17 hours.

Samples from asteroid Ryugu on their way to Earth

Hayabusa2 mapped the asteroid from orbit at high resolution, and later acquired samples of the primordial body from two landing sites. These are currently sealed in a transport capsule and are traveling to Earth with the spacecraft. The capsule is scheduled to land in Australia at the end of 2020. So far, the researchers assume that Ryugu's material is chemically similar to that of chondritic meteorites, which are also found on Earth. Chondrules are small, millimeter-sized spheres of rock, which formed in the primordial solar nebula 4.5 billion years ago and are considered to be the building blocks of planetary formation.

So far, however, scientists cannot rule out the possibility that they are made of carbon-rich material, such as that found on comet 67P/ Churyumov-Gerasimenko as part of ESA's Rosetta mission with the DLR-operated Philae lander. Analyses of the samples from Ryugu, some of which will be carried out at DLR, are eagerly awaited. "It is precisely for this task—and of course for future missions such as the Japanese "Martian Moons eXploration' (MMX) mission, in which extraterrestrial samples will be brought to Earth—that we at DLR's Institute of Planetary Research in Berlin began setting up the Sample Analysis Laboratory (SAL) last year," says Helbert. The MMX mission, in which DLR is participating, will fly to the Martian moons Phobos and Deimos in 2024 and bring samples from the asteroid-sized moons to Earth in 2029. A mobile German-French rover will also be part of the MMX mission.Small fragments of carbon-rich asteroids too fragile to survive atmospheric entry

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More information: Tatsuaki Okada et al. Highly porous nature of a primitive asteroid revealed by thermal imaging, Nature (2020). DOI: 10.1038/s41586-020-2102-6

Undetected cases may be driving coronavirus spread, study finds

by Dennis Thompson

You're a little feverish, but you feel good enough to get your shopping done and a quick workout at the gym.

If you do, you could become part of the exponential spread of the coronavirus, a new study concludes.

About 86% of COVID-19 cases in China were milder and went undetected during the two-week ramp-up of the epidemic in January, prior to the country imposing travel restrictions, researchers conclude in the March 16 issue of Science.

These undocumented cases of infection were "about half as infectious per person as a documented case who has more severe symptoms and may be shedding more," said senior researcher Jeffrey Shaman. He's a professor of environmental health sciences at Columbia University Mailman School of Public Health, in New York City.

However, "because there are many more of these undocumented cases, it's the undocumented infections that are driving the spread and growth of the outbreak," Shaman said.

The continued and widening lockdown of the United States is therefore the right move to limit the COVID-19 epidemic as much as possible, the researchers said.

On Monday, President Donald Trump announced during a media briefing that the U.S. Centers for Disease Control and Prevention now advises all Americans to avoid all gatherings of more than 10 people, avoid eating and drinking at restaurants, bars and food courts, and avoid discretionary travel for 15 days.

Coronavirus Task Force coordinator Dr. Deborah Birx said during the briefing that the latest step was taken because new modeling shows that a significant amount of the coronavirus' spread is fueled by "silent transmission."

Dr. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, was blunt about the coming weeks. "The worst is yet ahead for us," he said during the briefing. "It's how we respond to that challenge that will determine what the ultimate endpoint is going to be."

Across the country, many shops, schools, restaurants, bars and gyms have already closed in an effort to promote social distancing and keep people from infecting each other with coronavirus.

Another much-touted policy aimed at limiting the spread of COVID-19—travel bans—is not nearly as effective, a second study published recently in Science found.

Travel bans implemented inside China only delayed the spread of the epidemic by three to five days, while international bans halted the spread of coronavirus by about a few weeks, said senior researcher Alessandro Vespignani, director of the Network Science Institute at Northeastern University, in Boston.

"Travel restrictions alone do not really do much but delay the spread of the disease," said study co-author Elizabeth Halloran, a professor of biostatistics at the University of Washington School of Public Health, in Seattle. "Delaying is good because it slows things down, but the idea is that transmissibility really is key."

Reducing transmissibility includes detecting and isolating infected people, social distancing, school closures, increased hygiene, and overall improved awareness of the virus, Halloran said.

"Reduced travel and transmissibility does produce a synergistic effect, but it's the transmissibility that's more important," she concluded.

Trump has floated the idea of restricting domestic travel to California and Washington, but the two studies show this would be little more than a delaying tactic, experts said.

"The epidemic now is already seeded in the United States," Vespignani said. "We see ongoing local transmission in many states, and probably it's just the tip of the iceberg. Closing travel might delay the progression of the epidemic in some places and provide some time for preparation."

In the first study, Shaman and his colleagues created a computer model that tracked observations of reported infection and spread within China, as well as human movement within the country as revealed by mobile phone data.

The research team suspected that mild cases of COVID-19 were likely behind the ferocious spread of the virus in China, given human nature.

"If somebody is experiencing mild symptoms, and I think most of us can relate to this, we're still going to go about our day," Shaman said. "We'll still send the kids to school. We'll still go to work. If we have a little bit of a headache or slight fever, we might take some ibuprofen and still go out shopping and whatnot. It's that sort of continued contact with people that allows the silent transmission of many respiratory viruses."

To make sure the model was accurate, the researchers tested it by shutting off the infectiousness of undocumented COVID-19 cases, Shaman said—essentially assuming that no people with mild symptoms could infect others.

"When we do that, we see nearly an 80% reduction in the number of documented confirmed cases," Shaman said. "These people are the major driver of it. They're the ones who facilitated the spread. The undocumented infections which tend to be milder are distributing the virus broadly."

For the other study, Vespignani and his colleagues used computer modeling to compare travel between transportation hubs with the onward march of the novel coronavirus both inside China and to other countries.

Vespignani's team found that travel bans within a country are of limited use, but that international travel bans did have a substantial effect in slowing the virus' spread to other nations. Case importations were reduced by nearly 80% until mid-February, when the dam broke and the virus started reaching epidemic levels in other countries.

But the model also concluded that even with 90% travel reductions into and out of China, the number of imported cases in other countries still went up significantly in a matter of weeks. The only thing that halted that spread was a 50% or greater reduction of person-to-person transmission worldwide.Follow the latest news on the coronavirus (COVID-19) outbreak

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More information: The U.S. Centers for Disease Control and Prevention has more about COVID-19.

Expert sees tough slog ahead for workers, small businesses

by Harvard University

Credit: CC0 Public Domain

With stock markets plummeting despite the federal government's recent steps to try to bolster the economy, worries that COVID-19 could do lasting economic damage are rising. The Gazette spoke with Harvard Business School's Willy Shih, the Robert and Jane Cizik Professor of Management Practice, about lessons learned from China, which appears to have wrestled the epidemic there under control—reporting just a handful of new cases daily—and where people and companies are slowly getting back to work.

Q&A: Willy Shih

GAZETTE: As the epidemic wanes in China and rises here, what are you seeing about 

COVID-19's economic impact?

SHIH: I think there will be a dawning realization that we are depriving an awful lot of people of income, especially contract employees, seasonal employees, restaurant employees, hotel, airlines, and stuff like that. We saw this happen in China. All these service employees, restaurants, hotels, airlines, entertainment venues, all those people didn't have work and didn't have the income to drive any consumption. That's a huge problem. Also, in China a lot more businesses run on a cash basis. If they run out of cash, they go out of business or they don't have the ability to stay open. For service businesses that's a huge problem, but there are also small suppliers and supply chains for maybe third-, fourth-, fifth-tier suppliers. If small suppliers make a critical component and they go out of business, that's a whole different set of problems and that eventually catches up to companies here. What's ironic is that China is getting back to business and we go from the "supply shock" that we saw early in the pandemic—and which is still unfolding because of transportation delays—but as they sort out that supply shock, we run into the "demand shock" as the economy slows on our side and on the European side.

GAZETTE: So China is starting to try to get back to work?

SHIH: They are. Most of the big manufacturers are probably up to 80 percent or 90 percent. But anytime you stop a giant supply-chain machine with all these moving parts, getting everything going again and coordinated is difficult. When the factories started up, a lot of them were shorthanded, and then there was a shortage of truck drivers. If you think of how much material moves in and out of these factories all the time, sorting out all those transportation logistics—just getting enough truck drivers to get containers in the right place—is a challenge. Farther down the logistics chain, maybe 10 days ago, there was a big problem in the ports of Los Angeles and Long Beach because there had been so many so-called "blank sailings" from Asia. Blank sailing is the industry euphemism for "Hey, we're not going to run a ship on that line because we don't have any cargo." There was a decrease in ships coming into Los Angeles and Long Beach, so there was nobody to take the empty containers from prior trips back. So the empty containers were sitting there blocking export traffic. They didn't have anywhere to put them. Finally, a couple of the big shipping lines sent some of their mega ships just to take the empties back. So you have this coordination problem, and everything is out of balance. In normal times, this really is a well-oiled machine. All these interlocking pieces all work together. When you stop everything and try to start it up again, they start at different rates, and everything is out of coordination until people can rebalance everything.

GAZETTE: Is it more difficult if everyone's not at the same place in the cycle? We're still shutting down.

SHIH: We're still shutting down, and we'll probably see more shutdowns. U.S. factories that relied on Asia for components are getting their last shipments about now, as they work through the distribution centers. At some point, they're going to run out of inventory, and then there'll be a lot of supply surprises because you only need to be short one part to shut down an auto assembly line. Meanwhile you'll also see demand collapsing, with so many contract workers and gig employees suddenly losing their income. That takes a lot of purchasing power out of the economy and starts hitting demand—unless you're talking about toilet paper.

GAZETTE: I want to ask you about toilet paper because, like many people, I've been wondering why everyone is hoarding toilet paper.

SHIH: I wrote this piece in Forbes about COVID-19, shortage gaming, and the toilet-paper supply chain. Demand for toilet paper is flat. It's not as if there's seasonal demand for toilet paper. Therefore, if you're a manufacturer, what you do is optimize your supply chain for stable demand. So then there's this panic. Fear is driving it and that creates shortages, which creates even more fear. People are saying, "I'm going to be stuck for two weeks, four weeks." But you don't need a five-year supply. When you buy the five-year supply, that hurts people who don't have a lot of income and run their lives on a cash basis. They buy small quantities when they need it. It's the well-to-do who can go to Costco and buy a pallet load of toilet paper.

GAZETTE: When we talk about fear, we're seeing rising concern about the economy, with the S&P 500 and the Dow closing down about 12 percent Monday. How much of this is fear versus an understanding of what is going to be a certain amount of economic disruption? To what extent is this a reasonable reaction to what's going on?

SHIH: It's hard to give a precise answer. Obviously, it's a combination. For example, if you look at Harvard University and many other universities, there's what I think of as a very considered response. We haven't had the national leadership in terms of getting out ahead of this, when we had four weeks of warning. But you see a lot of institutions saying, "OK, we have to try not to overload the health care system, so let's make everybody work from home. Let's enhance this social distancing." So closing down the NBA and theaters and things like that enhance social distancing, and that will help us spread out the contagion so that the health care system can handle it. Amazon and Microsoft and Google and large employers instituted work from home pretty early. That necessarily will have economic impact, and I think everybody understands that, but the No. 1 thing we have to avoid as a country is having a health care system that is forced to make choices about who it can save and who it can't save.

GAZETTE: Has anyone thought about how many small businesses may not have the cushion to weather the storm? Bankruptcies are going to occur because of this. Has anybody put a number on that?

SHIH: I haven't seen it. I know there are people in Washington who are worried about it. We already saw this in China. This is going to be a problem here, with restaurants, all kinds of small businesses, small shops, and so on. If you have no revenue coming in and you have to cover your expenses, that's a problem. A lot of firms will feel compelled to conserve cash by laying off people. The airlines have a huge dilemma now. American is parking their entire widebody fleet. Companies like that are trying to preserve cash and employment, payroll, is a big part of it. But if you put them on furlough, there's a percentage of the American public that doesn't have even a small cushion to make it through an emergency. That's something we really have to worry about. This is going to be a tough time. It's the cash problem I'm worried about right now.

GAZETTE: You started to mention small businesses in China. Do we know what the impact has been?

SHIH: I have to rely on reports coming out of there because there isn't much travel back and forth, but you see a lot of reports about restaurants, small vendors, just out of cash right now. I was talking to a student about a family business that has a factory in China. We were talking about cash accounting and he said, "You know, I go to them and they don't have a lot of details on all their costs." I said, "Well, a lot of these businesses look at how much cash comes in every month and how much cash goes out. And, as long as the cash in is more than the cash out, then I'm OK." But when you have these dramatic cuts in cash in, especially the small shops, the restaurants and things like that, I think it's a gigantic problem over there.

GAZETTE: Are there any lessons that we can apply here?

SHIH: There was a lot of criticism about how China suppressed the early reports and wasted some critical weeks early on. You could say we did the same thing in this country in different ways. From an economic standpoint, I think one of the things that companies are going to need to do is think about supply-chain diversity and supplier risk. If you think about how global supply chains are structured right now, we think about lean manufacturing and really not having a lot of inventory on hand, because inventory costs you money. There's always the assumption that logistics are efficient, and I can move all this stuff around when I need it.

GAZETTE:: But aren't there people out there who view these kinds of events as simply rare and unpredictable?

SHIH: People talk about "black swan" events, that are not supposed to happen very often. But if you look at the last decade, we had the 2008‒2009 downturn. We had the earthquake and tsunami in Japan; we had the flooding in Thailand; we had the trade war with China. I don't know that black swan is the right name because they occur more often than we would assume. I would argue that the risk of those black swan events has not been priced into people's cost assumptions. People tend to ignore it right now. We should understand our supplier network a little bit better. Most companies have difficulty understanding who is deep in their supply chain. So, for example, I know who my first-tier suppliers are; they are the ones who supply me directly. But those suppliers have their own suppliers, and those suppliers have what to me are my third-tier suppliers. And it'll cascade down. Most companies don't know who their suppliers are beyond the second tier. So you end up with something happening to a third- or fourth-tier supplier that shuts you down. What we should learn from this is to understand our supply chain and then ask whether we should be diversifying our risk a little bit more. But I predict once this blows over we'll go back to how things were, because, frankly, if you want to diversify, it's going to be more expensive. If you think having a lot of risk in China is bad, it's really hard to diversify away from that, because China is such a large source and has such an efficient manufacturing system.

GAZETTE: What about lessons for individuals, those who might be laid off?

SHIH: In China, we did see companies lending employees to others. We're going to have a lot of people without work. In China, you saw a lot of people ended up taking delivery jobs because delivery rose, all of a sudden. I think there will be other surprises. Harvard has gone online, so we'll probably find that online education really evolves a lot. I wrote a case a number of years ago, after the east Japan earthquake and tsunami. There was a Sony factory in that area that was the sole supplier of SRW format digital videotape, which all the Hollywood studios used for their mastering. So there was a shortage of SRW tape, and the studios said, "We have to go to the archives and erase some of this tape so we can use it." But that drove the technology to so-called "file-based mastering." It's like they said, "Wait a minute. I don't need to store it on tape. I'll just store it on a disk drive." And that that was one of the things that helped the transition to digital cinema. So we're going to see a lot of things like that. Already, in the Seattle area, more people are getting comfortable with online delivery of groceries, especially older people who don't tend to do that. They think, "I guess I'll try it," and find out, "Hey, this isn't so bad." We'll see a bunch of those.

GAZETTE: What do they say? Necessity is the mother of invention?

SHIH: Or something a contact at the Gates Foundation said, "Never waste a good crisis." Use this crisis to drive different forms of behavior. I think we'll find some surprising things.

GAZETTE: What are you looking for in the next days and weeks that are potentially important indicators of the impact of COVID-19 on the economy?

SHIH: The critical thing will be once the infection rates stop this exponential climb. Everybody's looking for that, the inflection point in the curve. That'll tell us when we can start planning for the recovery. Until that point, I worry that the economic damage is going to be quite significant. Like I said earlier, we had the supply shock, and it's getting sorted out. We'll have this wave of catch-up supply arriving on our shores just in time to meet this demand shock. Getting those things back in sync is going to take a while. It's not going to be something that we're done with by June. It's going to take longer than that. A lot of the airlines have reduced their flights through the summer, peak travel season. So that tells me that there are a lot of people who realize getting back to business as usual is going to take some time. We've got a tough slog ahead.

Explore furtherQ&A: Coronavirus likely to infect the global economy

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Why fake news about coronavirus is appealing (and how to avoid it)

by Melissa De Witte, Stanford University

Stanford’s Jeff Hancock shares why deceptive messages are appealing and what people can do to avoid bad advice – including checking information from established news sources rather than social media news feeds. Credit: Stanford HCI Group

As people increasingly social distance themselves to prevent the spread of the novel coronavirus, social media is an appealing way to stay in contact with friends, family and colleagues. But it can also be a source of misinformation and bad advice—some of it even dangerously wrong.

Here, Jeff Hancock, a professor of communication in Stanford's School of Humanities and Sciences and founding director of the Stanford Social Media Lab, shares why these deceptive messages are appealing and what people can do to avoid bad advice—including checking information from established news sources rather than social media news feeds.

What are the upsides and downsides of turning to social media during the novel coronavirus pandemic?

Social media is allowing us to learn about information in our social world in extremely rapid and far-flung ways. We can learn about coronavirus news in other parts of the world and our own backyards within seconds and minutes. Social media is also an important way of staying socially connected with one another, which is incredibly important for our psychological health as we all begin to engage in social distancing.

But having access to all this information can raise our anxiety since we tend to pay attention to bad news, and somewhat increased anxiety is a reasonable response.

How can people discern false information about the new coronavirus from accurate, medical advice?

It's important to check health-related information from established news sources rather than from shared stories in social media. A subscription to any reputable news organization is highly recommended, though many news sites (e.g., the New York Times) are offering free access to coronavirus related news.

Are there telltale signs people can look for when trying to discern fake versus real information online?

Compared to real news, fake news tends to include information that is more surprising, upsetting or geared to trigger anger or anxiety. Any information that fits that (and a lot of coronavirus news can) should be double checked. Other cues that should raise suspicion include unknown sources, unusual numbers of endorsements (or likes) and memes that focus on partisan topics.


As a scholar of social media and communication, have you noticed anything new about how the new coronavirus is discussed online?

I think social media communication is very much reflecting our fears and concerns with the virus, and this should be no surprise. As people struggle to learn more about it, to cope with the disruptions and seek to understand how they should deal with it, they are using social media to accomplish those goals and to express their fear and uncertainty.

What leads people to believe deceptive—and even dangerously wrong—information online?

When people are fearful they seek information to reduce uncertainty. This can lead people to believe information that may be wrong or deceptive because it helps make them feel better, or allows them to place blame about what's happening. This is often why conspiracy theories become so prominent. Again, the best antidote here is subscribing to a reputable news service.

Who is typically behind such misinformation campaigns and hoaxes? What is their motivation?

Because media business models are based on attention economics, bad actors create mal-information (which includes fake news, misinformation and disinformation) about the coronavirus in order to get people to attend to their content, and ultimately make money from that attention. Money is the primary motivation.

A second motivation is partisanship and partisans try to lay blame for the crisis with political opponents. The third main motivation is seeking to disrupt and confuse the public. This was the Russian election interference motivation for mal-information and remains their objective along with some other hostile state actors.

What can media platforms do to control mal-information? What can users do?

The immediate solution here has to come from the media platforms to remove this content and prevent mal-information from spreading on their platforms. This is an important responsibility that they simply cannot shirk. Longer-term, people need to be aware of these forms of mal-information, ensuring they check their sources and get their news from authoritative and reputable news services.


Explore furtherCoronavirus outbreak: Social media platforms scramble to contain misinformation

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