̽��ֱ�� of Cambridge - meteorite

How did the building blocks of life arrive on Earth?

sc604 — Fri, 11 Oct 2024 18:00:00 +0000

Volatiles are elements or compounds that change into vapour at relatively low temperatures. They include the six most common elements found in living organisms, as well as water. ̽��ֱ��zinc found in meteorites has a unique composition, which can be used to identify the sources of Earth’s volatiles.

̽��ֱ��researchers, from the ̽��ֱ�� of Cambridge and Imperial College London, have previously found that Earth’s zinc came from different parts of our Solar System: about half came from beyond Jupiter and half originated closer to Earth.

“One of the most fundamental questions on the origin of life is where the materials we need for life to evolve came from,” said Dr Rayssa Martins from Cambridge’s Department of Earth Sciences. “If we can understand how these materials came to be on Earth, it might give us clues to how life originated here, and how it might emerge elsewhere.”

Planetesimals are the main building blocks of rocky planets, such as Earth. These small bodies are formed through a process called accretion, where particles around a young star start to stick together, and form progressively larger bodies.

But not all planetesimals are made equal. ̽��ֱ��earliest planetesimals that formed in the Solar System were exposed to high levels of radioactivity, which caused them to melt and lose their volatiles. But some planetesimals formed after these sources of radioactivity were mostly extinct, which helped them survive the melting process and preserved more of their volatiles.

In a study published in the journal Science Advances, Martins and her colleagues looked at the different forms of zinc that arrived on Earth from these planetesimals. ̽��ֱ��researchers measured the zinc from a large sample of meteorites originating from different planetesimals and used this data to model how Earth got its zinc, by tracing the entire period of the Earth’s accretion, which took tens of millions of years.

Their results show that while these ‘melted’ planetesimals contributed about 70% of Earth’s overall mass, they only provided around 10% of its zinc.

According to the model, the rest of Earth’s zinc came from materials that didn’t melt and lose their volatile elements. Their findings suggest that unmelted, or ‘primitive’ materials were an essential source of volatiles for Earth.

“We know that the distance between a planet and its star is a determining factor in establishing the necessary conditions for that planet to sustain liquid water on its surface,” said Martins, the study’s lead author. “But our results show there’s no guarantee that planets incorporate the right materials to have enough water and other volatiles in the first place – regardless of their physical state.”

̽��ֱ��ability to trace elements through millions or even billions of years of evolution could be a vital tool in the search for life elsewhere, such as on Mars, or on planets outside our Solar System.

“Similar conditions and processes are also likely in other young planetary systems,” said Martins. “ ̽��ֱ��roles these different materials play in supplying volatiles is something we should keep in mind when looking for habitable planets elsewhere.”

̽��ֱ��research was supported in part by Imperial College London, the European Research Council, and UK Research and Innovation (UKRI).

Reference:
Rayssa Martins et al. ‘Primitive asteroids as a major source of terrestrial volatiles.’ Science Advances (2024). DOI: 10.1126/sciadv.ado4121

Researchers have used the chemical fingerprints of zinc contained in meteorites to determine the origin of volatile elements on Earth. ̽��ֱ��results suggest that without ‘unmelted’ asteroids, there may not have been enough of these compounds on Earth for life to emerge.

Rayssa Martins/Ross Findlay

An iron meteorite from the core of a melted planetesimal (left) and a chondrite meteorite, derived from a ‘primitive’, unmelted planetesimal (right).

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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New approach to ‘cosmic magnet’ manufacturing could reduce reliance on rare earths in low-carbon technologies

sc604 — Tue, 25 Oct 2022 00:35:10 +0000

A team from the ̽��ֱ�� of Cambridge, working with colleagues from Austria, found a new way to make a possible replacement for rare-earth magnets: tetrataenite, a ‘cosmic magnet’ that takes millions of years to develop naturally in meteorites.

Previous attempts to make tetrataenite in the laboratory have relied on impractical, extreme methods. But the addition of a common element – phosphorus – could mean that it’s possible to make tetrataenite artificially and at scale, without any specialised treatment or expensive techniques.

̽��ֱ��results are reported in the journal Advanced Science. A patent application on the technology has been filed by Cambridge Enterprise, the ̽��ֱ��’s commercialisation arm, and the Austrian Academy of Sciences.

High-performance magnets are a vital technology for building a zero-carbon economy, and the best permanent magnets currently available contain rare earth elements. Despite their name, rare earths are plentiful in Earth’s crust. However, China has a near monopoly on global production: in 2017, 81% of rare earths worldwide were sourced from China. Other countries, such as Australia, also mine these elements, but as geopolitical tensions with China increase, there are concerns that rare earth supply could be at risk.

“Rare earth deposits exist elsewhere, but the mining operations are highly disruptive: you have to extract a huge amount of material to get a small volume of rare earths,” said Professor Lindsay Greer from Cambridge’s Department of Materials Science & Metallurgy, who led the research. “Between the environmental impacts, and the heavy reliance on China, there’s been an urgent search for alternative materials that do not require rare earths.”

Tetrataenite, an iron-nickel alloy with a particular ordered atomic structure, is one of the most promising of those alternatives. Tetrataenite forms over millions of years as a meteorite slowly cools, giving the iron and nickel atoms enough time to order themselves into a particular stacking sequence within the crystalline structure, ultimately resulting in a material with magnetic properties approaching those of rare-earth magnets.

In the 1960s, scientists were able to artificially form tetrataenite by bombarding iron-nickel alloys with neutrons, enabling the atoms to form the desired ordered stacking, but this technique is not suitable for mass production.

“Since then, scientists have been fascinated with getting that ordered structure, but it’s always felt like something that was very far away,” said Greer. Despite many attempts over the years, it has not yet been possible to make tetrataenite on anything approaching an industrial scale.

Now, Greer and his colleagues from the Austrian Academy of Sciences and the Montanuniversität in Leoben, have found a possible alternative that doesn’t require millions of years of cooling or neutron irradiation.

̽��ֱ��team was studying the mechanical properties of iron-nickel alloys containing small amounts of phosphorus, an element that is also present in meteorites. ̽��ֱ��pattern of phases inside these materials showed the expected tree-like growth structure called dendrites.

“For most people, it would have ended there: nothing interesting to see in the dendrites, but when I looked closer, I saw an interesting diffraction pattern indicating an ordered atomic structure,” said first author Dr Yurii Ivanov, who completed the work while at Cambridge and is now based at the Italian Institute of Technology in Genoa.

At first glance, the diffraction pattern of tetrataenite looks like that of the structure expected for iron-nickel alloys, namely a disordered crystal not of interest as a high-performance magnet. It took Ivanov’s closer look to identify the tetrataenite, but even so, Greer says it’s strange that no one noticed it before.

̽��ֱ��researchers say that phosphorus, which is present in meteorites, allows the iron and nickel atoms to move faster, enabling them to form the necessary ordered stacking without waiting for millions of years. By mixing iron, nickel and phosphorus in the right quantities, they were able to speed up tetrataenite formation by between 11 and 15 orders of magnitude, such that it forms over a few seconds in simple casting.

“What was so astonishing was that no special treatment was needed: we just melted the alloy, poured it into a mould, and we had tetrataenite,” said Greer. “ ̽��ֱ��previous view in the field was that you couldn’t get tetrataenite unless you did something extreme, because otherwise, you’d have to wait millions of years for it to form. This result represents a total change in how we think about this material.”

While the researchers have found a promising method to produce tetrataenite, more work is needed to determine whether it will be suitable for high-performance magnets. ̽��ֱ��team are hoping to work on this with major magnet manufacturers.

̽��ֱ��work may also force a revision of views on whether the formation of tetrataenite in meteorites really does take millions of years.

̽��ֱ��research was supported in part by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme and Seventh Framework Programme, and the Austrian Science Fund.

Reference:
Yurii P Ivanov et al. ‘Direct formation of hard-magnetic tetrataenite in bulk alloy castings.’ Advanced Science (2022). DOI: 10.1002/advs.202204315

For more information on energy-related research in Cambridge, please visit Energy IRC, which brings together Cambridge’s research knowledge and expertise, in collaboration with global partners, to create solutions for a sustainable and resilient energy landscape for generations to come.

Researchers have discovered a potential new method for making the high-performance magnets used in wind turbines and electric cars without the need for rare earth elements, which are almost exclusively sourced in China.

Between the environmental impacts, and the heavy reliance on China, there’s been an urgent search for alternative materials that do not require rare earths

Lindsay Greer

Rob Lavinsky, iRocks.com

Tetrataenite found in Nuevo Mercurio, Zacatecas, Mexico

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Microscopic view on asteroid collisions could help us understand planet formation

cmm201 — Thu, 24 Feb 2022 10:00:43 +0000

A team of researchers, led by the ̽��ֱ�� of Cambridge, combined dating and microscopic analysis of the Chelyabinsk meteorite — which fell to Earth and hit the headlines in 2013 — to get more accurate constraints on the timing of ancient impact events.

Their study, published in Communications Earth & Environment, looked at how minerals within the meteorite were damaged by different impacts over time, meaning they could identify the biggest and oldest events that may have been involved in planetary formation.

“Meteorite impact ages are often controversial: our work shows that we need to draw on multiple lines of evidence to be more certain about impact histories – almost like investigating an ancient crime scene,” said Craig Walton, who led the research and is based at Cambridge’s Department of Earth Sciences.

Early in our Solar System’s history, planets including the Earth formed from massive collisions between asteroids and even bigger bodies, called proto-planets.

“Evidence of these impacts is so old that it has been lost on the planets — Earth, in particular, has a short memory because surface rocks are continually recycled by plate tectonics,” said co-author Dr Oli Shorttle, who is based jointly at Cambridge’s Department of Earth Sciences and Institute of Astronomy.

Asteroids, and their fragments that fall to Earth as meteorites, are in contrast inert, cold and much older— making them faithful timekeepers of collisions.

̽��ֱ��new research, which was a collaboration with researchers from the Chinese Academy of Sciences and the Open ̽��ֱ��, recorded how phosphate minerals inside the Chelyabinsk meteorite were shattered to varying degrees in order to piece together a collision history.

Their aim was to corroborate uranium-lead dating of the meteorite, which looks at the time elapsed for one isotope to decay to another.

“ ̽��ֱ��phosphates in most primitive meteorites are fantastic targets for dating the shock events experienced by the meteorites on their parent bodies,” said Dr Sen Hu, who carried out the uranium-lead dating at Beijing’s Institute of Geology and Geophysics, Chinese Academy of Sciences.

Previous dating of this meteorite has revealed two impact ages, one older, roughly 4.5-billion-year-old collision and another which occurred within the last 50 million years.

But these ages aren’t so clear-cut. Much like a painting fading over time, successive collisions can obscure a once clear picture, leading to uncertainty among the scientific community over the age and even the number of impacts recorded.

̽��ֱ��new study put the collisions recorded by the Chelyabinsk meteorite in time order by linking new uranium-lead ages on the meteorite to microscopic evidence for collision-induced heating seen inside their crystal structures. These microscopic clues build up in the minerals with each successive impact, meaning the collisions can be distinguished, put in time order and dated.

Their findings show that minerals containing the imprint of the oldest collision were either shattered into many smaller crystals at high temperatures or strongly deformed at high pressures.

̽��ֱ��team also described some mineral grains in the meteorite that were fractured by a lesser impact, at lower pressures and temperatures, and which record a much more recent age of less than 50 million years. They suggest this impact probably chipped the Chelyabinsk meteorite off its host asteroid and sent it hurtling to Earth.

Taken together, this supports a two-stage collision history. “ ̽��ֱ��question for us was whether these dates could be trusted, could we tie these impacts to evidence of superheating from an impact?” said Walton. “What we’ve shown is that the mineralogical context for dating is really important.”

Scientists are particularly interested in the date of the 4.5-billion-year-old impact because this is about the time we think the Earth-Moon system came to being, probably as a result of two planetary bodies colliding.

̽��ֱ��Chelyabinsk meteorite belongs to a group of so-called stony meteorites, all of which contain highly shattered and remelted material roughly coincident with this colossal impact.

̽��ֱ��newly acquired dates support previous suggestions that many asteroids experienced high energy collisions between 4.48 – 4.44 billion years ago. “ ̽��ֱ��fact that all of these asteroids record intense melting at this time might indicate Solar System re-organisation, either resulting from the Earth-Moon formation or perhaps the orbital movements of giant planets.”

Walton now plans to refine dating over the window of the Moon-forming impact, which could tell us how our own planet came to being.

Reference:
Walton, C.R. et al. ‘Ancient and recent collisions revealed by phosphate minerals in the Chelyabinsk meteorite.’ Communications Earth & Environment (2022). DOI: 10.1038/s43247-022-00373-1

A new way of dating collisions between asteroids and planetary bodies throughout our Solar System’s history could help scientists reconstruct how and when planets were born.

Our work shows that we need to draw on multiple lines of evidence to be more certain about impact histories – almost like investigating an ancient crime scene

Craig Walton

False-colour image of impact recrystallised phosphate mineral in Chelyabinsk meteorite

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Meteorite impact turns silica into stishovite in a billionth of a second

Anonymous — Tue, 13 Oct 2015 12:49:29 +0000

̽��ֱ��Barringer meteor crater is an iconic Arizona landmark, more than 1km wide and 170 metres deep, left behind by a massive 300,000 tonne meteorite that hit Earth 50,000 years ago with a force equivalent to a ten megaton nuclear bomb. ̽��ֱ��forces unleashed by such an impact are hard to comprehend, but a team of Stanford scientists has recreated the conditions experienced during the first billionths of a second as the meteor struck in order to reveal the effects it had on the rock underneath.

̽��ֱ��sandstone rocks of Arizona were, on that day of impact 50,000 years ago, pushed beyond their limits and momentarily – for the first few trillionths and billionths of a second – transformed into a new state. ̽��ֱ��Stanford scientists, in a study published in the journal Nature Materials, recreated the conditions as the impact shockwave passed through the ground through computer models of half a million atoms of silica. Blasted by fragments of an asteroid that fell to Earth at tens of kilometres a second, the silica quartz crystals in the sandstone rocks would have experienced pressures of hundreds of thousands of atmospheres, and temperatures of thousands of degrees Celsius.

What the model reveals is that atoms form an immensely dense structure almost instantaneously as the shock wave hits at more than 7km/s. Within ten trillionths of a second the silica has reached temperatures of around 3,000℃ and pressures of more than half a million atmospheres. Then, within the next billionth of a second, the dense silica crystallises into a very rare mineral called stishovite.

̽��ֱ��results are particularly exciting because stishovite is exactly the mineral found in shocked rocks at the Barringer Crater and similar sites across the globe. Indeed, stishovite (named after a Russian high-pressure physics researcher) was first found at the Barringer Crater in 1962. ̽��ֱ��latest simulations give an insight into the birth of mineral grains in the first moments of meteorite impact.

Simulations show how crystals form in billionths of a second

̽��ֱ��size of the crystals that form in the impact event appears to be indicative of the size and nature of the impact. ̽��ֱ��simulations arrive at crystals of stishovite very similar to the range of sizes actually observed in geological samples of asteroid impacts.

Studying transformations of minerals such as quartz, the commonest mineral of Earth’s continental crust, under such extreme conditions of temperature and pressure is challenging. To measure what happens on such short timescales adds another degree of complexity to the problem.

These computer models point the way forward, and will guide experimentalists in the studies of shock events in the future. In the next few years we can expect to see these computer simulations backed up with further laboratory studies of impact events using the next generation of X-ray instruments, called X-ray free electron lasers, which have the potential to “see” materials transform under the same conditions and on the same sorts of timescales.

Simon Redfern, Professor in Earth Sciences, ̽��ֱ�� of Cambridge

This article was originally published on ̽��ֱ��Conversation. Read the original article.

Inset image: Barringer meteor Crater, Arizona (NASA Earth Observatory).

̽��ֱ��opinions expressed in this article are those of the individual author(s) and do not represent the views of the ̽��ֱ�� of Cambridge.

Simon Redfern from the Department of Earth Sciences discusses a study that has recreated the conditions experienced during the meteor strike that formed the Barringer Crater in Arizona.

United States Geological Survey/D. Roddy

Barringer Crater aerial photo

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Death of a dynamo – a hard drive from space

sc604 — Wed, 21 Jan 2015 18:00:01 +0000

̽��ֱ��dying moments of an asteroid’s magnetic field have been successfully captured by researchers, in a study that offers a tantalising glimpse of what may happen to the Earth’s magnetic core billions of years from now.

Using a detailed imaging technique, the research team were able to read the magnetic memory contained in ancient meteorites, formed in the early solar system over 4.5 billion years ago. ̽��ֱ��readings taken from these tiny ‘space magnets’ may give a sneak preview of the fate of the Earth’s magnetic core as it continues to freeze. ̽��ֱ��findings are published today (22 January) in the journal Nature.

Using an intense beam of x-rays to image the nanoscale magnetisation of the meteoritic metal, researchers led by the ̽��ֱ�� of Cambridge were able to capture the precise moment when the core of the meteorite’s parent asteroid froze, killing its magnetic field. These ‘nano-paleomagnetic’ measurements, the highest-resolution paleomagnetic measurements ever made, were performed at the BESSY II synchrotron in Berlin.

̽��ֱ��researchers found that the magnetic fields generated by asteroids were much longer-lived than previously thought, lasting for as long as several hundred million years after the asteroid formed, and were created by a similar mechanism to the one that generates the Earth’s own magnetic field. ̽��ֱ��results help to answer many of the questions surrounding the longevity and stability of magnetic activity on small bodies, such as asteroids and moons.

“Observing magnetic fields is one of the few ways we can peek inside a planet,” said Dr Richard Harrison of Cambridge’s Department of Earth Sciences, who led the research. “It’s long been assumed that metal-rich meteorites have poor magnetic memories, since they are primarily composed of iron, which has a terrible memory – you wouldn’t ever make a hard drive out of iron, for instance. It was thought that the magnetic signals carried by metal-rich meteorites would have been written and rewritten many times during their lifetime, so no-one has ever bothered to study their magnetic properties in any detail.”

̽��ֱ��particular meteorites used for this study are known as pallasites, which are primarily composed of iron and nickel, studded with gem-quality silicate crystals. Contained within these unassuming chunks of iron however, are tiny particles just 100 nanometres across – about one thousandth the width of a human hair – of a unique magnetic mineral called tetrataenite, which is magnetically much more stable than the rest of the meteorite, and holds within it a magnetic memory going back billions of years.

“We’re taking ancient magnetic field measurements in nanoscale materials to the highest ever resolution in order to piece together the magnetic history of asteroids – it’s like a cosmic archaeological mission,” said PhD student James Bryson, the paper’s lead author.

̽��ֱ��researchers’ magnetic measurements, supported by computer simulations, demonstrate that the magnetic fields of these asteroids were created by compositional, rather than thermal, convection – meaning that the field was long-lasting, intense and widespread. ̽��ֱ��results change our perspective on the way magnetic fields were generated during the early life of the solar system.

These meteorites came from asteroids formed in the first few million years after the formation of the Solar System. At that time, planetary bodies were heated by radioactive decay to temperatures hot enough to cause them to melt and segregate into a liquid metal core surrounded by a rocky mantle. As their cores cooled and began to freeze, the swirling motions of liquid metal, driven by the expulsion of sulphur from the growing inner core, generated a magnetic field, just as the Earth does today.

“It’s funny that we study other bodies in order to learn more about the Earth,” said Bryson. “Since asteroids are much smaller than the Earth, they cooled much more quickly, so these processes occur on shorter timescales, enabling us to study the whole process of core solidification.”

Scientists now think that the Earth’s core only began to freeze relatively recently in geological terms, maybe less than a billion years ago. How this freezing has affected the Earth’s magnetic field is not known. “In our meteorites we’ve been able to capture both the beginning and the end of core freezing, which will help us understand how these processes affected the Earth in the past and provide a possible glimpse of what might happen in the future,” said Harrison.

However, the Earth’s core is freezing rather slowly. ̽��ֱ��solid inner core is getting bigger, and eventually the liquid outer core will disappear, killing the Earth’s magnetic field, which protects us from the Sun’s radiation. “There’s no need to panic just yet, however,” said Harrison. “ ̽��ֱ��core won’t completely freeze for billions of years, and chances are, the Sun will get us first.”

̽��ֱ��research was funded by the European Research Council (ERC) and the Natural Environment Research Council (NERC).

Hidden magnetic messages contained within ancient meteorites are providing a unique window into the processes that shaped our solar system, and may give a sneak preview of the fate of the Earth’s core as it continues to freeze.

It’s like a cosmic archaeological mission

James Bryson

̽��ֱ��Esquel pallasite from the Natural History Museum collections, consists of gem-quality crystals of the silicate mineral olivine embedded in a matrix of iron-nickel alloy.

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