Category: The Conversation

Source: The Conversation – UK – By Rachael Attwood, Programme Leader for History, Department of Humanities, University of Westminster

Research by charity End Sexism in Schools has found that over half of history lessons delivered to children aged 11 to 14 in England feature no women at all. With the government set to allocate funding to boost the provision of school libraries, here are some books – for a range of ages – to open young eyes to women’s lives, experiences and marginalisation in our past.

Books that strike a balance between being age appropriate, featuring rich, well-researched context and capturing the attention are top of my list. If they focus on lesser-known women in history, all the better.

For primary school children, biographical collections dominate the field. Take Kate Pankhurst’s Fantastically Great Women Who Changed the World. This book introduces young historians to a host of inspiring women from different ethnicities and backgrounds, while carefully setting out the circumstances and barriers that each woman faced in her time and place. The cartoon illustrations and accessible format of the text are a sure-fire classroom pleaser.

Kay Woodward’s What Would She Do? Advice from Iconic Women in History does a similar job for children aged around nine upwards, but with an added participatory element. It presents readers with the real-life dilemmas that the iconic women faced and encourages empathetic problem solving – what would she do? It also underscores the importance of resilience.

Vashti Harrison’s Little Leaders. Bold Women in Black History is an excellent choice. Meanwhile Rachel Ignotofsky’s Women in Science introduces young readers to women of diverse backgrounds, from antiquity to the 20th century, who have made their mark in maths, science and technology.

Along with the books compiling sketches of notable women’s lives, there are growing numbers of detailed biographies for primary school children that illuminate women’s place in the past. In the mainstream, there’s the Little People, Big Dreams series. My favourites feature architect Zaha Hadid, singer Aretha Franklin and artist Louise Bourgeois.

Particularly engaging historical biographies for children include Counting on Katherine, the story of Katherine Johnson, an African-American mathematician whose orbital calculations were instrumental in early US space missions. Kathleen Krull’s inspirational story of American lawyer and Supreme Court justice Ruth Bader Ginsburg also deserves a mention, along with Haydn Kaye’s book on the British suffragist pioneer Emmeline Pankhurst.

Women’s rights

My own research includes a focus on early 20th-century feminist activism. I’ve read Kay Barnham’s Women’s Rights and Suffrage with my six year old. It examines women’s historical legal status and political resistance from a global perspective. Then there’s David Roberts’ beautifully illustrated Suffragette: The Battle for Equality and Susan Campbell Bartoletti’s How Women Won the Vote. These books document the key ideologies and objectives of Edwardian British suffragism.

But what about the ordinary women of history, those of us who did not crusade or trailblaze – or at least not in public? Sadly, few books aimed at primary school children address this question head on. However, there is hope on the horizon for teens.

My 13-year-old daughter’s current favourite book is the teen edition of Philippa Gregory’s Normal Women. Making History for 900 Years. Gregory gives a detailed account of the lives of a diverse array of women over this broad time period in English history, highlighting the role of patriarchy and women’s subjugation in everyday life. With accessible language, relatable stories and illustrations, Normal Women is a surefire hit with older children trying to make sense of their place in the world.

Kate Mosse’s Feminist History for Every Day of the Year is also a captivating read, supplementing the multi-biography of notable women format with relative unknowns, for an older audience.

This kind of work, which goes beyond celebrating the famous few and sets out to write women back into the past, represents real progress in historical works for the next generation.

Rachael Attwood does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

– ref. Fifteen books to help children learn about women’s place in history – https://theconversation.com/fifteen-books-to-help-children-learn-about-womens-place-in-history-266084

Source: The Conversation – UK – By Christopher Watson, Professor, Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast

On October 6 1995, at a scientific meeting in Florence, Italy, two Swiss astronomers made an announcement that would transform our understanding of the universe beyond our solar system. Michel Mayor and his PhD student Didier Queloz, working at the University of Geneva, announced they had detected a planet orbiting a star other than the Sun.

The star in question, 51 Pegasi, lies about 50 light years away in the constellation Pegasus. Its companion – christened 51 Pegasi b – was unlike anything written in textbooks about how we thought planets might look. This was a gas giant with a mass of at least half that of Jupiter, circling its star in just over four days. It was so close to the star (1/20th of Earth’s distance from the Sun, well inside Mercury’s orbit) that the planet’s atmosphere would be like a furnace, with temperatures topping 1,000°C.

The instrument behind the discovery was Elodie, a spectrograph that had been installed two years earlier at the Haute-Provence observatory in southern France. Designed by a Franco-Swiss team, Elodie split starlight into a spectrum of different colours, revealing a rainbow etched with fine dark lines. These lines can be thought of as a “stellar barcode”, providing details on the chemistry of other stars.

What Mayor and Queloz spotted was 51 Pegasi’s barcode sliding rhythmically back-and-forth in this spectrum every 4.23 days – a telltale signal that the star was being wobbled back and forth by the gravitational tug of an otherwise unseen companion amid the glare of the star.

After painstakingly ruling out other explanations, the astronomers finally decided that the variations were due to a gas giant in a close-in orbit around this Sun-like star. The front page of the Nature journal in which their paper was published carried the headline: “A planet in Pegasus?”

The discovery baffled scientists, and the question-mark on Nature’s front cover reflected initial skepticism. Here was a purported giant planet next to its star, with no known mechanism for forming a world like this in such a fiery environment.

While the signal was confirmed by other teams within weeks, reservations about the cause of the signal remained for almost three years before being finally ruled out. Not only did 51 Pegasi b become the first planet discovered orbiting a Sun-like star outside our Solar System, but it also represented an entirely new type of planet. The term “hot Jupiter” was later coined to describe such planets.

This discovery opened the floodgates. In the 30 years since, more than 6,000 exoplanets (the term for planets outside our Solar System) and exoplanet candidates have been catalogued.

Their variety is staggering. Not only hot but ultra-hot Jupiters with a dayside temperature exceeding 2,000 °C and orbits of less than a day. Worlds that orbit not one but two stars, like Tatooine from Star Wars. Strange “super-puff” gas giants larger than Jupiter but with a fraction of the mass. Chains of small rocky planets all piled up in tight orbits.

The discovery of 51 Pegasi b triggered a revolution and, in 2019, landed Mayor and Queloz a Nobel prize. We can now infer that most stars have planetary systems. And yet, of the thousands of exoplanets found, we have yet to find a planetary system that resembles our own.

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Read more:
Nobel Prize in Physics: how the first exoplanet around a sun-like star was discovered

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The quest to find an Earth twin – a planet that truly resembles Earth in size, mass and temperature – continues to drive modern-day explorers like us to search for more undiscovered exoplanets. Our expeditions may not take us on death-defying voyages and treks like the past legendary explorers of Earth, but we do get to visit beautiful, mountain-top observatories often located in remote areas around the world.

We are members of an international consortium of planet hunters that built, operate and maintain the Harps-N spectrograph, mounted on the Telescopio Nazionale de Galileo on the beautiful Canary island of La Palma. This sophisticated instrument allows us to rudely interrupt the journey of starlight which may have been travelling unimpeded at speeds of 670 million miles per hour for decades or even millennia.

Each new signal has the potential to bring us closer to understanding how common planetary systems like our own may (or may not) be. In the background lies the possibility that one day, we may finally detect another planet like Earth.

The origins of exoplanet study

Up until the mid-1990s, our Solar System was the only set of planets humanity ever knew. Every theory about how planets formed and evolved stemmed from these nine, incredibly closely spaced data-points (which went down to eight when Pluto was demoted in 2006, after the International Astronomical Union agreed a new definition of a planet).

All of these planets revolve around just one star out of the estimated 10¹¹ (roughly 100 billion) in our galaxy, the Milky Way – which is in turn one of some 10¹¹ galaxies throughout the universe. So, trying to draw conclusions from the planets in our Solar System alone was a bit like aliens trying to understand human nature by studying students living together in one house. But that didn’t stop some of the greatest minds in history speculating on what lay beyond.

The ancient Greek philosopher Epicurus (341-270BC) wrote: “There is an infinite number of worlds – some like this world, others unlike it.” This view was not based on astronomical observation but his atomist theory of philosophy. If the universe was made up of an infinite number of atoms then, he concluded, it was impossible not to have other planets.

Epicurus clearly understood what this meant in terms of the potential for life developing elsewhere: “We must not suppose that the worlds have necessarily one and the same shape. Nobody can prove that in one sort of world there might not be contained – whereas in another sort of world there could not possibly be – the seeds out of which animals and plants arise and all the rest of the things we see.”

In contrast, at roughly the same time, fellow Greek philosopher Aristotle (384-322 BC) was proposing his geocentric model of the universe, which had the Earth immobile at its centre with the Moon, Sun and known planets orbiting around us. In essence, the Solar System as Aristotle conceived it was the entire universe. In On the Heavens (350BC), he argued: “It follows that there cannot be more worlds than one.”

Such thinking that planets were rare in the universe persisted for 2,000 years. Sir James Jeans, one of the world’s top mathematicians and an influential physicist and astronomer at the time, advanced his tidal hypothesis of planet formation in 1916. According to this theory, planets were formed when two stars pass so closely that the encounter pulls streams of gas off the stars into space, which later condense into planets. The rareness of such close cosmic encounters in the vast emptiness of space led Jeans to believe that planets must be rare, or – as was reported in his obituary – “that the solar system might even be unique in the universe”.

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But by then, understanding of the scale of the universe was slowly changing. In the “Great Debate” of 1920, held at the Smithsonian Museum of Natural History in Washington DC, American astronomers Harlow Shapley and Heber Curtis clashed over whether the Milky Way was the entire universe, or just one of many galaxies. The evidence began to point to the latter, as Curtis had argued for. This realisation – that the universe contained not just billions of stars, but billions of galaxies each containing billions of stars – began to affect even the most pessimistic predictors of planetary prevalence.

In the 1940s, two things caused the scientific consensus to pivot dramatically. First, Jeans’ tidal hypothesis did not stand up to scientific scrutiny. The leading theories now had planet formation as a natural byproduct of star formation itself, opening up the potential for all stars to host planets.

Then in 1943, claims emerged of planets orbiting the stars 70 Ophiuchus and 61 Cygni c – two relatively nearby star systems visible to the naked eye. Both were later shown to be false positives, most likely due to uncertainties in the telescopic observations that were possible at the time – but nonetheless, it greatly influenced planetary thinking. Suddenly, billions of planets in the Milky Way was considered a genuine scientific possibility.

For us, nothing highlights this change in mindset more than an article written for the Scientific American in July 1943 by the influential American astronomer Henry Norris Russell. Whereas two decades earlier, Russell had predicted that planets “should be infrequent among the stars”, now the title of his article was: “Anthropocentrism’s Demise. New Discoveries Lead to the Probability that There Are Thousands of Inhabited Planets in our Galaxy”.

Strikingly, Russell was not merely making a prediction about any old planets, but inhabited ones. The burning question was: where were they? It would take another half-century to begin finding out.

How to detect an exoplanet

When we observe myriad stars through La Palma’s Italian-built Galileo telescope using our Harps-N spectrograph, it is amazing to consider how far we have come since Mayor and Queloz announced their discovery of 51 Pegasi b in 1995. These days, we can effectively measure the masses of not just Jupiter-like planets, but even small planets thousands of light years away. As part of the Harps-N collaboration, we have had a front-row seat since 2012 in the science of small exoplanets.

Another milestone in this story came four years after the 51 Pegasi b discovery, when a Canadian PhD student at Harvard University, David Charbonneau, detected the transit of a known exoplanet. This was another hot Jupiter, known as HD209458b, also located in the Pegasus constellation, about 150 light years from Earth.

Transit refers to a planet passing in front of its star, from the perspective of the observer, momentarily making the star appear dimmer. As well as detecting exoplanets, the transit technique enables us to measure the radius of the planet by taking many brightness measurements of a star, then waiting for it to dim due to the passing planet. The extent of blocked starlight depends on the radius of the planet. For example, Jupiter would make the Sun 1% dimmer to alien observers, while for Earth, the effect would be a hundred times weaker.

In all, four times more exoplanets have now been discovered using this transit technique compared with the “barcode” technique, known as radial velocity, that the Swiss astronomers used to spot the first exoplanet 30 years ago. It is a technique that is still widely used today, including by us, as it can not only find a planet but also measure its mass.

A planet orbiting a star exerts a gravitational pull which causes that star to wobble back and forth – meaning it will periodically change its velocity with respect to observers on Earth. With the radial velocity technique, we take repeated measurements of the velocity of a star, looking to find a stable periodic wobble that indicates the presence of a planet.

These velocity changes are, however, extremely small. To put it in perspective, the Earth makes the Sun change its velocity by a mere 9cm per second – slower than a tortoise. In order to find planets with the radial velocity technique, we thus need to measure these small velocity changes for stars that are many many trillions of miles away from us.

The state-of-the-art instruments we use are truly an engineering feat. The latest spectrographs, such as Harps-N and also Espresso, can accurately measure velocity shifts of the order of tenths of centimetres per second – although still not sensitive enough to detect a true Earth twin.

But whereas this radial velocity technique is, for now, limited to ground-based observatories and can only observe one star at the time, the transit technique can be employed in space telescopes such as the French Corot (2006-14) and Nasa’s Kepler (2009-18) and Tess (2018-) missions. Between them, space telescopes have detected thousands of exoplanets in all their diversity, taking advantage of the fact we can measure stellar brightness more easily from space, and for many stars at the same time.

Despite the differences in detection success rate, both techniques continue to be developed. Applying both can give the radius and mass of a planet, opening up many more avenues for studying its composition.

To estimate possible compositions of our discovered exoplanets, we start by making the simplified assumption that small planets are, like Earth, made up of a heavy iron-rich core, a lighter rocky mantle, some surface water and a small atmosphere. Using our measurements of mass and radius, we can now model the different possible compositional layers and their respective thickness.

This is still very much a work in progress, but the universe is spoiling us with a wide variety of different planets. We’ve seen evidence of rocky worlds being torn apart and strange planetary arrangements that hint at past collisions. Planets have been found across our galaxy, from Sweeps-11b in its central regions (at nearly 28,000 light years away, one of the most distant ever discovered) to those orbiting our nearest stellar neighbour, Proxima Centauri, which is “only” 4.2 light years away.

Searching for ‘another Earth’

In early July 2013, one of us (Christopher) was flying out to La Palma for my first “go” with the recently commissioned Harps-N spectrograph. Keen not to mess up, my laptop was awash with spreadsheets, charts, manuals, slides and other notes. Also included was a three-page document I had just been sent, entitled: Special Instructions for ToO (Target of Opportunity).

The first paragraph stated: “The Executive Board has decided that we should give highest priority to this object.” The object in question was a planetary candidate thought to be orbiting Kepler-78, a star a little cooler and smaller than our Sun, located about 125 light years away in the direction of the constellation Cygnus.

A few lines further down read: “July 4-8 run … Chris Watson” with a list of ten times to observe Kepler-78 – twice per night, each separated by a very specific four hours and 15 minutes. The name above mine was Didier Queloz’s (he hadn’t been awarded his Nobel prize yet, though).

This planetary candidate had been identified by the Kepler space telescope, which was tasked with searching a portion of the Milky Way to look for exoplanets as small as the Earth. In this case, it had identified a transiting planet candidate with an estimated radius of 1.16 (± 0.19) Earth radii – an exoplanet not that much larger than Earth had potentially been spotted.

I was in La Palma to attempt to measure its mass which, combined with the radius from Kepler, would allow the density and possible composition to be constrained. I wrote at the time: “Want 10% error on mass, to get a good enough bulk density to distinguish between Earth-like, iron-concentrated (Mercury), or water.”

In all, I took ten out of our team’s total of 81 exposures of Kepler-78 in an observing campaign lasting 97 days. During that time, we became aware of a US-led team who were also looking for this potential planet. In true scientific spirit, we agreed to submit our independent findings at the same time. On the specified date. Like a prisoner swap, the two teams exchanged results – which agreed. We had, within the uncertainties of our data, reached the same conclusion about the planet’s mass.

Its most likely mass came out as 1.86 Earth masses. At the time, this made Kepler-78b the smallest extrasolar planet with an accurately measured mass. The density was almost identical to that of Earth’s.

But that is where the similarities to our planet ended. Kepler-78b has a “year” that lasts only 8.5 hours, which is why I had been instructed to observe it every 4hr 15min – when the planet was at opposite sides of its orbit, and the induced “wobble” of the star would be at its greatest. We measured the star wobbling back and forth at about two metres per second – no more than a slow jog.

Kepler-78b’s short orbit meant its extreme temperature would cause all rock on the planet to melt. It may have been the most Earth-like planet found at the time in terms of its size and density, but otherwise, this hellish lava world was at the very extremes of our known planetary population.

In 2016, the Kepler space telescope made another landmark discovery: a system with at least five transiting planets around a Sun-like star, HIP 41378, in the Cancer constellation. What made it particularly exciting was the location of these planets. Where most transiting planets we have spotted are closer to their star than Mercury is to the Sun (due to our detection capabilities), this system has at least three planets beyond the orbital radius of Venus.

Having decided to use our Harps-N spectrograph to measure the masses of all five transiting planets, it became clear after more than a year of observing that one instrument would not be enough to analyse this challenging mix of signals. Other international teams came to the same conclusion and, rather than compete, we decided to come together in a global collaboration that holds strong to this day, with hundreds of radial velocities gathered over many years.

We now have firm masses and radii for most of the planets in the system. But studying them is a game of patience. With planets much further away from their host star, it takes much longer before there is a new transit event or the periodic wobble can be fully observed. We thus need to wait multiple years and gather lots of data to gain insight in this system.

The rewards are obvious, though. This is the first system that starts resembling our Solar System. While the planets are a bit larger and more massive than our rocky planets, their distances are very similar – helping us to understand how planetary systems form in the universe.

The holy grail for exoplanet explorers

After three decades of observing, a wealth of different planets have emerged. We started with the hot Jupiters, large gas giants close to their star that are among the easiest planets to find due to both deeper transits and larger radial velocity signals. But while the first tens of discovered exoplanets were all hot Jupiters, we now know these planets are actually very rare.

With instrumentation getting better and observations piling up, we have since found a whole new class of planets with sizes and masses between those of Earth and Neptune. But despite our knowledge of thousands of exoplanets, we still have not found systems truly resembling our solar system, nor planets truly resembling Earth.

It is tempting to conclude this means we are a unique planet in a unique system. While this still could be true, it is unlikely. The more reasonable explanation is that, for all our stellar technology, our capabilities of detecting such Earth-like planets are still fairly limited in a universe so mind-bogglingly vast.

The holy grail for many exoplanet explorers, including us, remains to find this true Earth twin – a planet with a similar mass and radius as Earth’s, orbiting a star similar to the Sun at a distance similar to how far we are from the Sun.

While the universe is rich in diversity and holds many planets unlike our own, discovering a true Earth twin would be the best place to start looking for life as we know it. Currently, the radial velocity method – as used to find the very first exoplanet – remains by far the best-placed method to find it.

Thirty years on from that Nobel-winning discovery, pioneering planetary explorer Didier Queloz is taking charge of the very first dedicated radial velocity campaign to go in search of an Earth-like planet.

A major international collaboration is building a dedicated instrument, Harps3, to be installed later this year at the Isaac Newton Telescope on La Palma. Given its capabilities, we believe a decade of data should be enough to finally discover our first Earth twin.

Unless we are unique after all.

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For you: more from our Insights series:

• How Britain got its first internet connection – by the late pioneer who made it happen
  

• ‘Deep inside, something told me I had found the earliest human ancestor; I went numb’ – Yohannes Haile-Selassie on his lifetime quest to discover ancient humanity
  

• Noise in the brain enables us to make extraordinary leaps of imagination. It could transform the power of computers too
  

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Christopher Watson receives funding from the Science and Technology Facilities Council (STFC).

Annelies Mortier receives funding from the Science and Technology Facilities council (STFC) and UK Research and Innovation (UKRI).

– ref. How to discover a planet – https://theconversation.com/how-to-discover-a-planet-266550

Source: The Conversation – UK – By Rod Thornton, Senior Lecturer in International Studies, Defence and Security., King’s College London

Five Nato countries neighbouring Russia or its ally, Belarus, have announced that they are to opt out of the Ottawa treaty of 1997.

This treaty bans the use by signatories of anti-personnel (AP) landmines. These states – Poland, Finland, Lithuania, Estonia and Latvia – now have plans to create a 2,000-mile stretch of mined areas as part of a defensive effort against any possible attack from Russia.

The move to create such minefields comes as the result of both a recognition of the perceived growing threat from Russia and of the important defensive effect – as proved during the current Ukraine war – that both AP and anti-tank (AT) landmines can generate.

AT mines are not covered by the Ottawa treaty and all countries are free to use them. AT mines target only vehicles (the weight of a human cannot set them off). The main issue with AP mines, which target humans, is that they can be set off by civilians as well as soldiers.

As such, they are deemed to be not only indiscriminate weapons but also those whose “persistence” means that they can remain a danger long after any conflict is over. Their banning is seen by many as an “ethical imperative”.

In the current era of military development dominated by the introduction of high-tech weapons systems, it appears that the low-tech, unsophisticated and relatively cheap landmine – which can be laid in their millions – can have a significant role to play in modern warfare.

Minefields have proved very effective as a defensive tool in the current Ukraine war because of their ability to disrupt enemy assaults. This recognition has, for these five Nato states, meant that their adherence to the Ottawa treaty had to end, despite its grounding in humanitarian concerns.

These five states have been criticised by human rights organisations for withdrawing from the treaty. The UK was also a signatory in 1997 and still remains bound by its stipulations. The US, Russia and China didn’t sign in the first place.

The role of landmines

Landmines have proved a significant defensive tool in the Ukraine war. In the initial days of Russia’s full-scale invasion in February 2022, the Ukrainian side was very quick to deploy some of its stockpile of Soviet-era AT mines.

These were very effective in restricting the early advance of Russian armoured columns (the term “armour” covering both tanks and other armoured vehicles) on Kyiv. These mines created disruption as Russian forces were either stopped or had to find other routes around the minefields.

The delays allowed time for Ukrainian forces to set up firm defensive positions that eventually halted the Russian columns and led to their being turned back before reaching Kyiv.

Ukrainian forces then launched their own armoured offensive in the summer of 2023. These forces, by now trained and equipped by Nato states and using trademark Nato combined arms manoeuvre warfare techniques, were also held up in dense Russian minefields. Their advance ground to a halt.

The presence of vast fields of both AP and AT mines meant that the supposedly war-winning principal of “manoeuvre warfare”, which relies on movement, initiative and surprise, and which the Ukrainians had been taught by Nato instructors, became impossible to conduct. The Russians call their defensive minefields “insurmountable”.

Given the power of minefields, both sides came ultimately to understand that their presence had to mean a rethink of how the war should be conducted. Mines led to a change in tactics.

Both sides had to adopt much more attritional approaches. Outcomes would now largely be dictated by the weight of artillery fire and not by manoeuvre. It is minefields that form the basis for the Ukrainian forces’ “fortress belt” across much of the Donbas region.

Despite Kyiv having itself signed the Ottawa treaty in 2005, it was clear that its forces were making considerable use of banned AP mines along with the “legal” AT mines.

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Read more:
Ukraine joins other Russian neighbours in quitting landmines treaty: another deadly legacy in the making

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Ukraine only officially withdrew from Ottawa in June this year. Ukrainian president Volodymyr Zelensky justified the withdrawal on the basis that “antipersonnel mines … very often have no alternative as a tool for defence”.

The Russian defensive arrangements like those of Ukrainian forces make considerable use of mines. The Russian side is able to draw on what is perceived to be the world’s largest stockpile of, in particular, AP mines (said to be amount to some 26.5 million). Zelensky has accused Russia of using AP mines “with extreme cynicism”, (referring to the alleged booby trapping of dead Russian soldiers with AP mines).

Old tech with big impact

What is interesting here is that the very old technology of landmines is being combined with the far newer one of drones. Minefields can now be laid far more efficiently by using drones to plant them rather than, as has been the norm, by hand. The drones have changed how mine warfare is carried out.

Given what is happening in Ukraine, it is now well understood that mines can do more than help decide the course of mere tactical military engagements; they can create strategic outcomes. They can, in essence, decide the outcome of wars.

It is with this understanding in mind that these five Nato states have withdrawn from the Ottawa treaty. AP mines are patently needed on today’s battlefields. They are seen as an essential addition to the AT mines. Each type has their defensive role to play.

As such, these five states are now seeking to both procure their own AP mines domestically and to source them from the US. Somewhat controversially, the administration of former US president, Joe Biden, had already taken a decision, just before Donald Trump became president, to supply Ukraine with considerable numbers of “non-persistent” AP mines. At the time, Kyiv was still a signatory to Ottawa.

AP and AT mines have both proved themselves to be essential tools of modern warfare. Today, the war in Ukraine is characterised and dominated, due to the presence of mines, by defence and not offence. Frontlines are largely static. Humble, cheap and simple they may be, but landmines do, it seems, have a crucial role to play in modern warfare.

The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.

– ref. European countries are now turning to landmines to create new deadly defensive barriers from Russia – https://theconversation.com/european-countries-are-now-turning-to-landmines-to-create-new-deadly-defensive-barriers-from-russia-266181

Source: The Conversation – UK – By Seán Jordan, Associate Professor in Chemistry, Dublin City University

Recently, Nasa revealed exciting details of new findings from Mars. Scientists have
discovered tiny patterns of unusual minerals in the clay-rich rocks on the edge of
Jezero Crater – an ancient lake once fed by Martian river systems, and the
exploration site of the Nasa Perseverance Rover.

These “leopard spot” patterns have been hailed as a potential sign of past microbial life due to their similarity with traces left behind by microorganisms on Earth.

The jury is still out on whether these are actually signs of life, but this discovery has reignited the discussion about the previous existence of life on Mars, and the possibility that it could still survive there today.

We’ll need many different lines of evidence to answer this question, but there is precedence for considering certain Martian environments as currently habitable.

Early Earth and early Mars were relatively similar, but this similarity didn’t last long. Both had atmospheres and magnetic fields that offered some protection from harmful radiation originating from the Sun, along with bodies of liquid water on their surface. We know that these conditions led to the origin of life on Earth, so it is possible that the same could have happened on Mars.

While life on Earth was beginning to thrive, Mars lost its magnetic field as its core cooled. This exposed the planet to harmful solar rays which began to erode the
atmosphere. As the atmosphere disappeared, the Martian surface became colder
and drier, eventually becoming the freezing desert we know today.

This is why many scientists don’t expect to find living organisms on the surface of
Mars – it is simply too inhospitable for life as we know it. Instead, the hope lies in uncovering microbial life hidden in protected underground or icy regions.

Where could life survive on Mars?

Possible locations for Martian microbial life include caves, inside or underneath ice sheets at the poles, or deep underground. All of these environments have analogues (environments with certain similarities) on Earth that host microorganisms. So it is not much of a stretch to consider that if life began on Mars, it could still be holding on in these extreme niches.

Perhaps the most plausible of these is underground – the Martian subsurface. Extending from a few metres to several kilometres deep, it is thought to be the planet’s most stable and long-lived potential habitat.

While the surface has been cold, dry, and generally inhospitable for much of Martian history, the deep subsurface may have offered more favourable conditions. On Earth, the deep biosphere – the life that survives beneath the surface – provides a useful comparison.

A substantial amount of Earth’s microbial life exists underground, surviving in cracks within rocks. These ecosystems are dominated by lithoautotrophs – microbes that get energy by feeding on those rocks. Methane, a potential byproduct of some
lithoautroph feeding habits, has even been detected on Mars. But there are many
ways to generate methane underground without life, so right now this doesn’t tell us much.

The potential for a deep biosphere hinges on factors including the availability of
liquid water, a source of energy, space to live in, and tolerable temperatures. There is possible evidence for the existence of liquid water below the surface of Mars, but this is still under debate.

This would facilitate chemical reactions known as water-rock reactions which generate energy for microbes to live on. Because of its weaker gravity, rocks on Mars may be less compressed than those on Earth and remain more porous at depth, providing space for microbes to live in.

At the same time, Mars produces less heat from its interior, which means temperatures suitable for life could extend nearly twice as deep underground as they do on Earth.

Scientists spend a lot of time analysing places on Earth – Mars analogues – to try to understand the possibilities for past and present life on Mars. These environments are not identical to Mars, but they share at least one important feature such as extreme dryness, high salt levels, or high UV exposure.

Earth’s deep subsurface is one example, and others include the Atacama Desert in South America, sediments at Lake Salda in Turkey, and salts found in Utah’s Pilot Valley. Researchers around the world are investigating these sites on Earth to better understand how Martian conditions might affect life and its preservation. As no one location on Earth could possibly match all Martian conditions, scientists also run controlled laboratory experiments.

An example of this is the use of specialised “Mars chambers” to reproduce Martian environmental conditions such as its atmosphere, radiation exposure, and temperature. All of these investigations combined help us to better understand the potential for life to exist on Mars.

Signs of life today?

Right now there is no conclusive evidence of life on Mars past or present. Nasa’s
“leopard spots” are the most promising signs we have, but these are still
inconclusive. If life exists on Mars today, it is almost certainly not widespread like on Earth – our probes and rovers would have seen it.

However, important opportunities lie ahead. The upcoming European Space Agency (Esa) ExoMars Rosalind Franklin rover will be able to drill up to two metres below the Martian surface. This will give us a chance to study the shallow subsurface of Mars which may contain living microorganisms. But this is only the start—most scientists agree that we will need to go deeper.

Drilling deep on Earth is still a huge challenge and there is so much we don’t know about our own subsurface life. Probing the deep subsurface of Mars will be a major scientific and engineering challenge, but one that may hold the key to finding existing Martian life.

Seán Jordan receives funding from the European Research Council (ERC) under the European Union’s Horizon Europe research and innovation programme (grant agreement No 1101114969) and from Research Ireland (Pathway award 22/PATH-S/10692). He is affiliated with the Research Ireland Centre for Applied Geosciences (iCRAG).

Devyani Jambhule receives funding from the Research Ireland Pathway Award ((22/PATH-S/10692). She is affiliated with the Origin of Life Early-career Network (OoLEN).

– ref. Could life exist on Mars today? Here’s what the latest evidence says – https://theconversation.com/could-life-exist-on-mars-today-heres-what-the-latest-evidence-says-265735