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Scientists track veil of toxic metals carried in Kīlauea’s gas plumes, revealing hidden dangers of volcanic pollution

Tue, 25/05/2021 - 17:53

The research, published in two companion papers in Nature Communications Earth and Environment, is the most extensive survey of metal release from any volcano to date – helping scientists understand the spread of metal-rich volcanic fumes and the exposure of communities to volcanic air pollution around Hawai’i.

The 2018 eruption of Kīlauea was the largest in centuries, flooding the eastern edge of the island with roughly a cubic kilometres of lava. Over a thousand people lost their homes and many more suffered from noxious volcanic gases.  

Understanding how volcanic metals are released to the environment is critical from a public health perspective, “We don’t know much about these metal emissions at all, so this work is a key step to understanding the significant, yet underestimated, chemical risks of volcanoes,” said Emily Mason, PhD student at Cambridge Earth Sciences and lead author of one of the papers.

When volcanoes erupt they exhale a cocktail of gases – mostly steam, carbon dioxide and sulphur dioxide – laced with evaporated heavy metals, including lead and arsenic. To the communities living alongside volcanoes, these gases are often a considerable source of air pollution and the volatile metals they carry may have long-lasting impacts on both health and environment. 

Volcanologists have been measuring volatile metal emissions from volcanoes for decades, but how these elements are dispersed in the atmosphere following an eruption, to later rain down on the landscape and be taken up in the environment through soils and water bodies, has remained poorly understood.

The team, including researchers from the University of Cambridge, report higher concentrations of airborne heavy metals within a 40 km radius of Kīlauea, meaning that communities living closer to the volcano were disproportionally exposed to metal pollution during the 2018 eruption.

They believe that the strong trade winds at the time of the eruption, combined with the topography of the local area, caused higher rainfall and, therefore metal deposition, closer to the vent. This could mean that an eruption in winter, when wind patterns are reversed, might result in a different distribution of metal deposition.

Their results could help delineate environmental monitoring strategies during and following eruptions – including the targeted testing of community water supplies in at-risk areas – as well as helping planners decide where to build safely around volcanoes.

Emily Mason was one of an all-female team of scientists from the Universities of Cambridge and Leeds that headed out to take gas measurements when Kīlauea erupted. Mason, together with then first-year PhD students Penny Wieser and Rachel Whitty, and early career scientists Evgenia Ilyinskaya and Emma Liu, arrived when the eruption was in full flow and some of their study area was already cut off by lava, “We had to fly in to one location via helicopter. I remember descending through a dense haze of volcanic gas…the acidic air actually stung our skin.” said Mason.

“We tend to think of the more immediate volcanic hazards like ash fall, pyroclastic flows, lava,” said Dr Evgenia Ilyinskaya, from the University of Leeds, who led the research on downwind metal dispersal, “But metal emissions, just like air pollution, are an insidious and often underestimated volcanic hazard – potentially impacting health over long periods.”

During the first few weeks of the eruption, the main air quality concern was volcanic smog, or ‘vog’, which contains mostly sulfur dioxide with traces of heavy metals and volcanic ash. But when molten lava reached the ocean and reacted with seawater it triggered new health warnings, as billowing white clouds of lava haze or ‘laze’ were released; carrying hydrochloric acid and toxic metals.  

Working with collaborators from the USGS, the team took measurements of gases inside the laze and dry vog plumes from both the ground and the air, using specially-fitted drones. They even developed a back frame for their air filters, so they could move equipment quickly through areas where the air was thick with sulphur dioxide.

Mason and co-authors discovered that the two types of gas plume had a very different chemistry, “What really surprised us was the large amounts of copper in the laze plume…the impact of lava-seawater interactions on the biosphere may be significantly underestimated. It’s interesting to note that this type of plume was probably a common feature of the massive outpourings of lava throughout geological history – some of which have been linked to mass extinctions.”

Their long-term goal is to produce pollution hazard maps for volcanoes, showing at-risk areas for metal pollution, a method already used to communicate areas that might be at risk of other volcanic hazards, like lava flows, “Our research is just one part of the puzzle – the idea would be to understand all of these hazards in tandem”.

They aim to apply this method worldwide, but Mason cautions that local atmospheric conditions significantly influence metal dispersal and deposition. Now they want to know how the transport of volcanic metals might differ in cooler, drier environments like the Antarctic – or even in different areas of Hawai’i where rainfall is lower.

 

Ilyinskaya, Evgenia, et al. "Rapid metal pollutant deposition from the volcanic plume of Kīlauea, Hawai’i." Communications Earth & Environment 2.1 (2021): 1-15.

Mason, Emily, et al. "Volatile metal emissions from volcanic degassing and lava–seawater interactions at Kīlauea Volcano, Hawai’i." Communications Earth & Environment 2.1 (2021): 1-16.

A team of volcanologists who observed the colossal 2018 eruption of Kīlauea, Hawai’i, have tracked how potentially toxic metals carried in its gas plumes were transported away from the volcano to be deposited on the landscape.

This work is a key step to understanding the significant, yet underestimated, chemical risks of volcanoesEmily MasonEmily Mason/USGSGolden Hour at Kīlauea


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Twelve Cambridge researchers awarded European Research Council funding

Thu, 22/04/2021 - 11:00

Two hundred and nine senior scientists from across Europe were awarded grants in today’s announcement, representing a total of €507 million in research funding. The UK has 51 grantees in this year’s funding round, the most of any ERC participating country.

ERC grants are awarded through open competition to projects headed by starting and established researchers, irrespective of their origins, who are working or moving to work in Europe. The sole criterion for selection is scientific excellence. ERC Advanced Grants are designed to support excellent scientists in any field with a recognised track record of research achievements in the last ten years. Apart from strengthening Europe’s knowledge base, the new research projects will also lead to the creation of some 1,900 new jobs for post-doctoral fellows, PhD students and other research staff. 

Professor Melinda Duer from the Yusuf Hamied Department of Chemistry has been awarded a grant for her EXTREME project to explore the chemistry that happens when a biological tissue stretches or breaks.

So-called mechanochemistry leads to molecules being generated within the tissue that may be involved in communicating tissue damage to cells. Detecting and understanding this chemistry is highly relevant for understanding ageing, and for developing new therapeutics for degenerative diseases and cancer.

“This award means I can do the research I’ve been dreaming about for the last ten years,” said Duer. “I am extremely grateful to the European Research Council for giving me this amazing opportunity. The ERC is one of the few organisations that understands the need for longer-term funding for high-risk, high-reward research, which is essential for this project. I really couldn’t be more delighted and I can’t wait to get started!”

Professor Manish Chhowalla, from the Department of Materials Science and Metallurgy, received funding for his 2D-LOTTO project, for the development of energy-efficient electronics.

“This grant will enable our research group to realise the next generation of energy-efficient electronics based on two-dimensional semiconductors,” he said. “The funding will also support a team of students, early career researchers and senior academics to address the challenges of demonstrating practical tunnel field effect transistors.”

Professor Henning Sirringhaus from the Cavendish Laboratory received funding for his NANO-DECTET project, for the development of next-generation energy materials. “Worldwide, only about a third of primary energy is converted into useful energy services: the other two thirds are wasted as heat in the various industrial, transportation, residential energy conversion and electricity generation processes,” said Sirringhaus. “Given the urgent need to mitigate the dangerous consequences of climate change, a waste of energy on this scale needs to be addressed immediately.

“Thermoelectric waste-heat-to-electricity conversion could offer a potential solution, but the performance of thermoelectric materials is currently insufficient. In this project we will use the unique physics of molecular organic semiconductors, as well as hybrid organic-inorganic semiconductors, to make efficient, low-temperature thermoelectric materials.”

Professor Marcos Martinon-Torres from the Department of Archaeology received funding for his REVERSEACTION project, which will study how societies in the past cooperated. “Many prehistoric societies did pretty well at maintaining rich and complex lives without the need for permanent power hierarchies and coercive authorities,” he said. “Arguably, they chose to cooperate, and not just to ensure survival. The lack of state structures did not stop them from developing and sustaining complex technologies, making extraordinary artefacts that required exotic materials, challenging skills and labour arrangements. I’m keen to understand why, but also how they managed.

“This grant couldn’t have come at a better time, as collective action is increasingly recognised as the only way to tackle some of our greatest global concerns, and there is value in studying how people collaborated in the past. With our labs freshly revamped through our recent AHRC infrastructure grant, we are ready to take on a new large-scale, challenging archaeological science project.”

Professor Marta Mirazon Lahr, also from the Department of Archaeology, was awarded funding for her NGIPALAJEM project, which will bring a new understanding of how the evolution of our species is part of a broader and longer African evolutionary landscape.

“My research is in human evolution, a field that advances through technical breakthroughs, new ideas, and critically, new fossils,” said Lahr. “A big part of my work is to find new hominin fossils in Africa, which requires not only supportive local communities and institutions, but long-term planning and implementation, a dedicated team, significant funds and the time to excavate, study, compare and interpret new discoveries. This new grant from the ERC gives me all this and more – and I just can’t wait to get started!”

Professor Richard Samworth’s RobustStats project will develop robust statistical methodology and theory for large-scale data. “Large-scale data are usually messy: they may be collected under different conditions, and data may be missing or corrupted, which makes it difficult to draw reliable conclusions,” said Samworth, from the Department of Pure Mathematics and Mathematical Statistics. “This grant will allow me to focus my time on developing robust statistical methodology and theory to address these challenges. Equally importantly, I will be able to build a group of PhD students and post-docs that will dramatically increase the scale and scope of what we are able to achieve.

Professor Zoran Hadzibabic from the Cavendish Laboratory was awarded funding for his UNIFLAT project. One of the great successes of the last-century physics was recognising that complex and seemingly disparate systems are fundamentally alike. This allowed the classification of the equilibrium states of matter into classes based on their basic properties. At the heart of this classification is the universal collective behaviour, insensitive to the microscopic details, displayed by systems close to phase transitions.

A grand challenge for modern physics is to achieve such a feat for the far richer world of the nonequilibrium collective phenomena. “Our ambition is to make a leading contribution to this worldwide effort, through a series of coordinated experiments on homogeneous atomic gases in two-dimensional (2D) geometry,” said Hadzibabic. “Specifically, we will study in parallel three problems – the dynamics of the topological Berezinskii-Kosterlitz-Thouless phase transition, turbulence in driven systems, and the universal spatiotemporal scaling behaviour in isolated quantum systems far from equilibrium. Each of these topics is fascinating and of fundamental importance in its own right, but beyond that we will experimentally establish an emerging picture that connects them.”

Dr Helen Williams from the Department of Earth Sciences said: “By funding the EarthMelt project, the ERC has given me the amazing opportunity to study the early evolution of the Earth and its transition from a largely molten state to the habitable planet we know today. This funding will also help me to develop exciting new instrumentation and analytical techniques, and, most importantly, mentor and support the next generation of PhD students and postdoctoral researchers working in geochemistry.”

Professor Sir Richard Friend from the Cavendish Laboratory has been awarded funding for his Spin Control in Radical Semiconductors (SCORS) project, which will explore the electronic properties of organic semiconductors that have an unpaired electron to give net magnetic spin. The project is based on a recent discovery that this unpaired electron can couple strongly to light, allowing very efficient luminescence in LEDs. Friend’s group will explore new combinations of optical excited states with magnetic spin states. This will allow new designs for LEDs and solar cells, and opportunities to control the ground state spin polarisation in spintronic devices.

Professor Christopher Hunter’s InfoMols project is focused on synthetic information molecules. “The aim of our project is replication and evolution with artificial polymers,” said Hunter, from the Yusuf Hamied Department of Chemistry. “The timeframe for achieving such a breakthrough is unpredictable, and it is the flexibility provided by an ERC award that makes tackling such challenging targets possible.”

Professor Mark Gross from the Department of Pure Mathematics and Mathematical Statistics received funding for his Mirror symmetry in Algebraic Geometry (MSAG) project, and Professor Geoffrey Khan from the Faculty of Asian and Middle Eastern Studies was awarded funding for ALHOME: Echoes of Vanishing Voices in the Mountains: A Linguistic History of Minorities in the Near East.

 

Twelve University of Cambridge researchers have won advanced grants from the European Research Council (ERC), Europe’s premier research funding body. Cambridge has the most grant winners of any UK institution, and the second-most winners overall. Their work is set to provide new insights into many subjects, such as how to deal with vast scales of data in a statistically robust way, the development of energy-efficient materials for a zero-carbon world, and the development of new treatments for degenerative disease and cancer.

University of CambridgeTop L-R: Helen Williams, Richard Friend, Richard Samworth, Melinda Duer. Bottom L-R: Chris Hunter, Marta Mirazon Lahr, Marcos Martinon-Torres, Manish Chhowalla


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From extravagant to achievable - pushing the boundaries of research to find life beyond Earth

Tue, 20/04/2021 - 12:27

Led by 2019 Physics Nobel Laureate Professor Didier Queloz, the Cambridge Initiative for Planetary Science and Life in the Universe will be the driving force for the development of a new Cambridge research community investigating life in the Universe, from understanding how it emerged on Earth to examining the processes that could make other planets suitable for life.

The initiative comes at a crucial moment in science, as scientists are able to study exoplanets – planets orbiting stars other than our Sun – in ever-greater detail, and outstanding progress is being made in prebiotic chemistry: carefully-regulated laboratory experiments to recreate the conditions when life first formed on Earth.

In addition, the recent successful landing of the Mars 2020 Perseverance Rover set in motion one of the greatest international scientific endeavours of recent decades. Within the next ten years, samples returned from a four-billion-year-old lake deposit on Mars will offer a unique window on the Solar System as it was when life originated on Earth and could provide evidence of ancient life on the Red Planet.

“These recent revolutions and future perspectives offered by next-generation space missions mean that the planets are aligned for us to create a vibrant new field at the cutting edge of modern science,” said Queloz, from Cambridge’s Cavendish Laboratory and Director of the Initiative.

Building on the University’s research excellence and enhancing the multidisciplinary research conducted in various departments of the School of the Physical Sciences, the focus of the research within the new Initiative will be to understand the origins and physical properties of planets throughout the Universe, as well as the chemical and biological processes capable of starting and sustaining life.

“By bringing together chemists, geologists, biologists, and astrophysicists to work creatively together toward a common goal, the Initiative will ensure we truly exploit the full potential of this exciting new field of research, bringing us closer to understanding life in the Universe and finding life beyond Earth,” said Queloz.

The School of the Physical Sciences and its various departments (Cavendish Laboratory, Chemistry, Applied Mathematics and Theoretical Physics, Earth Sciences and the Institute of Astronomy) recently committed to an initial funding package that will support the Initiative as it builds the foundations of its vision and will create the conditions for its research and educational ambitions to grow and develop.

Professor Nigel Peake, Head of the School of the Physical Sciences, said: “During the last decades our understanding of the microbiology of life has made spectacular progress, but knowledge on origins of life on Earth, and more generally in the Universe, are still nascent. This is about to change. I am proud that Cambridge is leading the way to a radically new approach based on a convergence of recent results in astrophysics, planetology and molecular chemistry.

“With the Cambridge Initiative for Planetary Science and Life in the Universe, we will provide the infrastructure that will allow scholars from various disciplines to combine their interests to address the fundamental question of our origins in the Universe. This sets the scene for a revolution to come.”

For more information, news and updates about the Cambridge Initiative for Planetary Science and Life in the Universe, visit www.iplu.phy.cam.ac.uk.

The University of Cambridge is creating a new research initiative, bringing together physicists, chemists, biologists, mathematicians, and earth scientists to answer fundamental questions on the origin and nature of life in the Universe.

By bringing together chemists, geologists, biologists, and astrophysicists to work toward a common goal, we can exploit the full potential of this exciting new field of research, bringing us closer to understanding life in the Universe and finding life beyond EarthDidier Queloz Prof. Didier Queloz introduces Cambridge IPLU NASA, ESA, G. Illingworth, D. Magee, and P. Oesch, R. Bouwens, and the HUDF09 TeamThe Hubble eXtreme Deep Field


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Scientists zero in on the role of volcanoes in the demise of dinosaurs

Mon, 29/03/2021 - 20:00

Earth has experienced five major extinction events over the last 500 million years, the fifth and most recent responsible for wiping out the dinosaurs 66 million years ago. Massive volcanic eruptions have been identified as a major driver in the environmental change which triggered at least three of these extinctions.

But what dealt the final blow to the dinosaurs – whether an enormous outpouring of lava from the Deccan Traps volcanic province in India or a large asteroid impact or perhaps a combination of the two – has remained open to debate.

Now, a multi-institutional research team, led by scientists from the City University of New York (CUNY), and involving the University of Cambridge, has, for the first time, accurately pinpointed the timing and amount of carbon released from Deccan Traps volcanic province. The new data means scientists can now assess the role of volcanism in climate shifts around the End-Cretaceous mass extinction. 

The team’s data show that CO2 outgassing from Deccan Traps magmas can explain a warming of Earth’s global temperatures by roughly 3 degrees Celsius during the early phases of Deccan volcanism, but shows that the warming had lessened by the time of the mass extinction event.

Their findings support the theory that later Deccan magmas were not releasing that much CO2, suggesting that volcanic carbon emissions didn’t play a major role in the dinosaur’s extinction.

“The results are important because they show that major volcanic events can release substantial amounts of CO2 not just from surface vents, but also from the large and complex plumbing systems that feed them. Even though volcanic carbon emissions alone couldn’t have triggered the mass extinction, our data highlights their influence on our planet's climate and habitability,” said co-author Professor Sally Gibson, from Cambridge's Department of Earth Sciences.

The team had to search through hundreds of Deccan lava samples to identify suitable candidates to profile for their trapped CO2 content. “In modern volcanic eruptions, such as the current one in Iceland, the CO2 is trapped in crystals that are embedded in glassy fragments of rapidly cooled magma, but these are fragile and not preserved in the 65 million-year-old Deccan Traps,” said Gibson.

Recent research has identified a global warming event that occurred several hundred thousand years before the End-Cretaceous extinction. Some scientists have linked the eruption of the Deccan Traps to this warming event, but there is debate over whether the lavas that erupted could have released enough CO2 into the atmosphere to cause it.  Adding to this mystery, the lava volumes that erupted during this time are relatively small compared to the volumes erupted during subsequent stages of Deccan Traps activity. A major challenge in this debate has been the lack of CO2 data on Deccan magmas from this time.

“The new data highlights that carbon outgassing from lava volumes alone couldn’t have caused that level of global warming. But, when we factored in outgassing from magmas that froze beneath the surface rather than erupting, we found that the Deccan Traps could have released enough CO2 to explain this warming event,” said lead-author Andres Hernandez Nava, a PhD student in The Graduate Center, CUNY Earth.

For their study, the team used lasers and beams of ions to measure the amount of CO2 inside tiny droplets of frozen magma trapped inside Deccan Traps crystals from the End Cretaceous time period. They also measured the amounts of other elements, such as barium and niobium, which are indicators for how much CO2 the magmas started out with. Finally, they performed modeling of latest Cretaceous climate to test the impacts of Deccan Traps carbon release on surface temperatures.

“Our lack of insight into the carbon released by magmas during some of Earth’s largest volcanic eruptions has been a critical gap for pinning down the role of volcanic activity in shaping Earth’s past climate and extinction events,” said Black, the study’s principal investigator and a professor in the Earth and Environmental Science program at The Graduate Center CUNY and City College of New York. “This work brings us closer to understanding the role of magmas in fundamentally shaping our planet’s climate, and specifically helps us test the contributions of volcanism and the asteroid impact in the end-Cretaceous mass extinction.”

 

Reference:
Hernandez Nava et al. Reconciling early Deccan Traps CO2 outgassing and pre-KPB global climate. PNAS (2021). DOI : 10.1073/pnas.2007797118

 

Adapted from a press release by The Graduate Center, CUNY.

Researchers have uncovered evidence suggesting that volcanic carbon emissions were not a major driver in Earth’s most recent extinction event.

Even though volcanic carbon emissions alone couldn’t have triggered the mass extinction, our data highlights their influence on our planet's climate and habitabilitySally GibsonLoÿc Vanderkluysen, Drexel UniversityDeccan Traps, India


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Traces of Earth’s early magma ocean identified in Greenland rocks

Fri, 12/03/2021 - 19:00

The study, published in the journal Science Advances, yields information on an important period in our planet’s formation, when a deep sea of incandescent magma stretched across Earth’s surface and extended hundreds of kilometres into its interior.

It is the gradual cooling and crystallisation of this ‘magma ocean’ that set the chemistry of Earth’s interior – a defining stage in the assembly of our planet’s structure and the formation of our early atmosphere.

Scientists know that catastrophic impacts during the formation of the Earth and Moon would have generated enough energy to melt our planet's interior. But we don’t know much about this distant and fiery phase of Earth’s history because tectonic processes have recycled almost all rocks older than 4 billion years.

Now researchers have found the chemical remnants of the magma ocean in 3.6-billion-year-old rocks from southwestern Greenland.

The findings support the long-held theory that Earth was once almost entirely molten and provide a window into a time when the planet started to solidify and develop the chemistry that now governs its internal structure. The research suggests that other rocks on Earth’s surface may also preserve evidence of ancient magma oceans.

“There are few opportunities to get geological constraints on the events in the first billion years of Earth’s history. It’s astonishing that we can even hold these rocks in our hands – let alone get so much detail about the early history of our planet,” said lead author Dr Helen Williams, from Cambridge’s Department of Earth Sciences.

The study brings forensic chemical analysis together with thermodynamic modelling in search of the primeval origins of the Greenland rocks, and how they got to the surface.

At first glance, the rocks that makeup Greenland’s Isua supracrustal belt look just like any modern basalt you’d find on the seafloor. But this outcrop, which was first described in the 1960s, is the oldest exposure of rocks on Earth. It is known to contain the earliest evidence of microbial life and plate tectonics.

The new research shows that the Isua rocks also preserve rare evidence which even predates plate tectonics – the residues of some of the crystals left behind as that magma ocean cooled.

“It was a combination of some new chemical analyses we did and the previously published data that flagged to us that the Isua rocks might contain traces of ancient material. The hafnium and neodymium isotopes were really tantalizing, because those isotope systems are very hard to modify – so we had to look at their chemistry in more detail,” said co-author Dr Hanika Rizo, from Carleton University.

Iron isotopic systematics confirmed to Williams and the team that the Isua rocks were derived from parts of the Earth’s interior that formed as a consequence of magma ocean crystallisation.

Most of this primeval rock has been mixed up by convection in the mantle, but scientists think that some isolated zones deep at the mantle-core boundary – ancient crystal graveyards – may have remained undisturbed for billions of years.

It’s the relics of these crystal graveyards that Williams and her colleagues observed in the Isua rock chemistry. “Those samples with the iron fingerprint also have a tungsten anomaly – a signature of Earth’s formation – which makes us think that their origin can be traced back to these primeval crystals,” said Williams.

But how did these signals from the deep mantle find their way up to the surface? Their isotopic makeup shows they were not just funnelled up from melting at the core-mantle boundary. Their journey was more circuitous, involving several stages of crystallization and remelting – a kind of distillation process. The mix of ancient crystals and magma would have first migrated to the upper mantle, where it was churned up to create a ‘marble cake’ of rocks from different depths. Later melting of that hybrid of rocks is what produced the magma which fed this part of Greenland.

The team’s findings suggest that modern hotspot volcanoes, which are thought to have formed relatively recently, may actually be influenced by ancient processes. “The geochemical signals we report in the Greenland rocks bear similarities to rocks erupted from hotspot volcanoes like Hawaii – something we are interested in is whether they might also be tapping into the depths and accessing regions of the interior usually beyond our reach,” said Dr Oliver Shorttle who is jointly based at Cambridge’s Department of Earth Sciences and Institute of Astronomy.

The team’s findings came out of a project funded by Deep Volatiles, a NERC-funded 5-year research programme. They now plan to continue their quest to understand the magma ocean by widening their search for clues in ancient rocks and experimentally modelling isotopic fractionation in the lower mantle.

“We’ve been able to unpick what one part of our planet’s interior was doing billions of years ago, but to fill in the picture further we must keep searching for more chemical clues in ancient rocks,” said co-author Dr Simon Matthews from the University of Iceland.

Scientists have often been reluctant to look for chemical evidence of these ancient events. “The evidence is often altered by the course of time. But the fact we found what we did suggests that the chemistry of other ancient rocks may yield further insights into the Earth’s formation and evolution - and that’s immensely exciting,” said Williams.

 

Reference:
Helen M. Williams et al. ‘Iron isotopes trace primordial magma ocean cumulates melting in Earth’s upper mantle.’ Science Advances (2021). DOI: 10.1126/sciadv.abc7394

New research led by the University of Cambridge has found rare evidence – preserved in the chemistry of ancient rocks from Greenland - which tells of a time when Earth was almost entirely molten.

It’s astonishing that we can even hold these rocks in our hands – let alone get so much detail about the early history of our planetHelen WilliamsHanika RizoIsua in Greenland


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Hubble sees new atmosphere forming on a rocky exoplanet

Thu, 11/03/2021 - 14:00

The planet GJ 1132 b appears to have begun life as a gaseous world with a thick blanket of atmosphere. Starting out at several times the radius of Earth, this ‘sub-Neptune’ quickly lost its primordial hydrogen and helium atmosphere, which was stripped away by the intense radiation from its hot, young star. In a short period of time, it was reduced to a bare core about the size of Earth.

To the surprise of astronomers, new observations from Hubble have uncovered a secondary atmosphere that has replaced the planet’s first atmosphere. It is rich in hydrogen, hydrogen cyanide, methane and ammonia, and also has a hydrocarbon haze. Astronomers theorise that hydrogen from the original atmosphere was absorbed into the planet’s molten magma mantle and is now being slowly released by volcanism to form a new atmosphere. This second atmosphere, which continues to leak away into space, is continually being replenished from the reservoir of hydrogen in the mantle’s magma.

“This second atmosphere comes from the surface and interior of the planet, and so it is a window onto the geology of another world,” said team member Paul Rimmer from the University of Cambridge. “A lot more work needs to be done to properly look through it, but the discovery of this window is of great importance.”

“We first thought that these highly radiated planets would be pretty boring because we believed that they lost their atmospheres,” said team member Raissa Estrela of the Jet Propulsion Laboratory at the California Institute of Technology in Pasadena, California, USA. “But we looked at existing observations of this planet with Hubble and realised that there is an atmosphere there.”

“How many terrestrial planets don’t begin as terrestrials? Some may start as sub-Neptunes, and they become terrestrials through a mechanism whereby light evaporates the primordial atmosphere. This process works early in a planet’s life, when the star is hotter,” said team leader Mark Swain of the Jet Propulsion Laboratory. “Then the star cools down and the planet’s just sitting there. So you’ve got this mechanism that can cook off the atmosphere in the first 100 million years, and then things settle down. And if you can regenerate the atmosphere, maybe you can keep it.”

In some ways, GJ 1132 b has various parallels to Earth, but in some ways, it is also very different. Both have similar densities, similar sizes, and similar ages, being about 4.5 billion years old. Both started with a hydrogen-dominated atmosphere, and both were hot before they cooled down. The team’s work even suggests that GJ 1132 b and Earth have similar atmospheric pressure at the surface.

However, the planets’ formation histories are profoundly different. Earth is not believed to be the surviving core of a sub-Neptune. And Earth orbits at a comfortable distance from our yellow dwarf Sun. GJ 1132 b is so close to its host red dwarf star that it completes an orbit the star once every day and a half. This extremely close proximity keeps GJ 1132 b tidally locked, showing the same face to its star at all times — just as our moon keeps one hemisphere permanently facing Earth.

“The question is, what is keeping the mantle hot enough to remain liquid and power volcanism?” asked Swain. “This system is special because it has the opportunity for quite a lot of tidal heating.”

The phenomenon of tidal heating occurs through friction, when energy from a planet’s orbit and rotation is dispersed as heat inside the planet. GJ 1132 b is in an elliptical orbit, and the tidal forces acting on it are strongest when it is closest to or farthest from its host star. At least one other planet in the host star’s system also exerts a gravitational pull on the planet. The consequences are that the planet is squeezed or stretched by this gravitational “pumping.” That tidal heating keeps the mantle liquid for a long time. A nearby example in our own Solar System is the Jovian moon, Io, which has continuous volcanism as a result of a tidal tug-of-war between Jupiter and the neighbouring Jovian moons.

The team believes the crust of GJ 1132 b is extremely thin, perhaps only hundreds of feet thick. That’s much too feeble to support anything resembling volcanic mountains. Its flat terrain may also be cracked like an eggshell by tidal flexing. Hydrogen and other gases could be released through such cracks.

“This atmosphere, if it’s thin — meaning if it has a surface pressure similar to Earth — probably means you can see right down to the ground at infrared wavelengths. That means that if astronomers use the James Webb Space Telescope to observe this planet, there’s a possibility that they will see not the spectrum of the atmosphere, but rather the spectrum of the surface,” said Swain. “And if there are magma pools or volcanism going on, those areas will be hotter. That will generate more emission, and so they’ll potentially be looking at the actual geological activity — which is exciting!”

This result is significant because it gives exoplanet scientists a way to figure out something about a planet's geology from its atmosphere,” said Rimmer, who is affiliated both with Cambridge’s Cavendish Laboratory and Department of Earth Sciences. “It is also important for understanding where the rocky planets in our own Solar System — Mercury, Venus, Earth and Mars, fit into the bigger picture of comparative planetology, in terms of the availability of hydrogen versus oxygen in the atmosphere.”

Adapted from an ESA/JPL press release.

 

For the first time, scientists using the NASA/ESA Hubble Space Telescope have found evidence of volcanic activity reforming the atmosphere on a rocky planet around a distant star. The planet, GJ 1132 b, has a similar density, size, and age to Earth.

It is a window onto the geology of another worldPaul RimmerNASA, ESA, and R. Hurt (IPAC/Caltech)Artist’s impression of the exoplanet GJ 1132 b


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