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St. Patricks Day usually conjures images of partying, Catholicism, Irish nationalism and, perhaps most famously, the color green: green clothes, green shamrocks, green beer and green rivers. So my students are often surprised when I tell them that St. Patricks Day was once a solemn feast day when youd be far more likely to see the color blue. In fact, theres even a color known as St. Patricks blue. True blue Historians dont know much about St. Patrick. But they believe he was born in the fifth century as Maewyn Succat. He wasnt Irish; rather he was born in Wales, the son of a Roman-British official. He was, however, captured by Irish pirates and enslaved in Ireland. After six years he went back to Britain but returned to Ireland as one of the missionaries to convert Irish pagans to Christianity. At some point he adopted the Latin name Patricius. In the 10th century, the first evidence of St. Patrick being a beloved figure in Ireland emerged. In the early 17th century, Luke Wadding, an Irish priest, persuaded the Catholic Church to make March 17 a feast day for St. Patrick. St. Patrick wasnt born in Ireland, but he did missionary work there. [Photo: Wikimedia Commons, CC BY] Back then, feast days were far from raucous affairs: Catholics typically went to Mass and then had a quiet dinner at home to celebrate. Other denominations, including Anglicans and Lutherans, recognized the day as well. But any commemorations would include the color blue. The Dublin Evening Post reported that in a 1785 St. Patricks Day ceremony in Dublin, a group of men identifying themselves as patriots marched in a grand procession round the garden, dressed in true blue, and carrying along with them a number of curious pageants. Constance Markievicz, who fought in the 1916 Easter Rebellion for independence and was the first minister of labour in the Irish Free State, maintained that blue was the old colour of Ireland. To connect the past to the nationalist movement, she used blue as the background for the Irish Citizen Armys flag. In 1934, Irish politician W.T. Cosgrave asserted that blue is in perfect, traditional, national accord with our history and in close association with the most revered and venerated memory of our patron Saint. Out with the old, in with the new Since the 12th century, Ireland had been a colony of Great Britain. Like the American Colonists who rebelled against the British crown, a group of rebels called the United Irish launched an insurrection in 1798 in a quest for independence. Led mostly by middle-class Protestants and in coordination with some Catholics, the United Irish adopted the wearing of the green to represent Irish nationalism and their fight against British imperialism. The rebellion failed, and the British government made Ireland part of the United Kingdom in 1801 to prevent future revolutions. The government also bestowed greater rights to Protestants over Catholics. Ireland became more sectarian over the course of the 19th century, and nationalism became more associated with Catholicism. In some ways, the two became interchangeable. With nationalism ascendant and Catholics outnumbering Protestants, green was widely embraced, particularly since it had been worn by the United Irish. Green crosses the pond Before the 1840s, most Irish immigrants to America had been Protestants, many of whom had been the descendants of Scottish settlers in Ulster and would later become known as the Scots Irish. Like those that would succeed them, they celebrated St. Patricks Day to commemorate their connection to Ireland. In the earliest recorded American celebration of the day, banquets toasting Ireland and St. Patrick took place in Boston in 1737. By the 1760s, annual parades were being held in New York and on the island of Montserrat to celebrate Irish culture and identity. Irish immigration to the new world increased dramatically after the Great Hunger of the 1840s, when the potato crops failed and over 1 million indigent Catholics arrived in the U.S. Facing discrimination from American Protestants who claimed they were more loyal to the pope than to the U.S., they viewed St. Patricks Day as a link to the history and culture of Ireland. Celebrations were a badge of pride and dignity, and they called for Irish independence to demonstrate they, too, believed in republican principles. Irish immigrants to the U.S. were eager to profess their embrace of the nations republican ideals. [Art: Transcendental Graphics/Getty Images] Irish nationalist groups active in the U.S. the Fenians, Clan na Gael and, later, Irish Northern Aid participated in these American St. Patricks Day parades, proudly wearing green to demonstrate their nationalism and the connection to past nationalist groups such as the United Irish. In Ireland, however, St. Patricks Day remained a solemn day of observance with little revelry. The Irish government didnt recognize St. Patricks Day as a public holiday until 1903, and the first parade in Dublin wasnt held until 1931. Even pubs remained closed on March 17 until 1961. Since 1922, when 26 of the 32 counties of Ireland became semi-independent, the tricolor flag of Ireland has been the official flag. Green represents the Catholics, orange represents the Protestants, and the white in the middle symbolizes peace. Yet green remains the color associated with St. Patricks Day and Ireland throughout the world, largely due to the Catholic diaspora and its association with nationalism. However, blue still plays a symbolic role in Ireland: Since 1945, the flag representing the president of Ireland has a gold harp with a dark blue background the color known as St. Patricks blue. The Irish presidential flag flies from the car of Irelands president. [Photo: Artur Widak/NurPhoto via Getty Images] Bryan McGovern is a professor of history at Kennesaw State University. This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Throughout history, when pioneers set out across uncharted territory to settle in distant lands, they carried with them only the essentials: tools, seeds and clothing. Anything else would have to come from their new environment. So they built shelter from local timber, rocks and sod; foraged for food and cultivated the soil beneath their feet; and fabricated tools from whatever they could scrounge up. It was difficult, but ultimately the successful ones made everything they needed to survive. Something similar will take place when humanity leaves Earth for destinations such as the Moon and Mars although astronauts will face even greater challenges than, for example, the Vikings did when they reached Greenland and Newfoundland. Not only will the astronauts have limited supplies and the need to live off the land; they wont even be able to breathe the air. Instead of axes and plows, however, todays space pioneers will bring 3D printers. As an engineer and professor who is developing technologies to extend the human presence beyond Earth, I focus my work and research on these remarkable machines. 3D printers will make the tools, structures and habitats space pioneers need to survive in a hostile alien environment. They will enable long-term human presence on the Moon and Mars. NASA astronaut Barry Wilmore holds a 3D-printed wrench made aboard the International Space Station. [Photo: NASA] From hammers to habitats On Earth, 3D printing can fabricate, layer by layer, thousands of things, from replacement hips to hammers to homes. These devices take raw materials, such as plastic, concrete or metal, and deposit it on a computerized programmed path to build a part. Its often called additive manufacturing, because you keep adding material to make the part, rather than removing material, as is done in conventional machining. Already, 3D printing in space is underway. On the International Space Station, astronauts use 3D printers to make tools and spare parts, such as ratchet wrenches, clamps and brackets. Depending on the part, printing time can take from around 30 minutes to several hours. For now, the print materials are mostly hauled up from Earth. But NASA has also begun recycling some of those materials, such as waste plastic, to make new parts with the Refabricator, an advanced 3D printer installed in 2019. Manufacturing in space You may be wondering why space explorers cant simply bring everything they need with them. After all, thats how the International Space Station was built decades ago by hauling tons of prefabricated components from Earth. But thats impractical for building habitats on other worlds. Launching materials into space is incredibly expensive. Right now, every pound launched aboard a rocket just to get to low Earth orbit costs thousands of dollars. To get materials to the Moon, NASA estimates the initial cost at around US$500,000 per pound. Still, manufacturing things in space is a challenge. In the microgravity of space, or the reduced gravity of the Moon or Mars, materials behave differently than they do on Earth. Decrease or remove gravity, and materials cool and recrystallize differently. The Moon has one-sixth the gravity of Earth; Mars, about two-fifths. Engineers and scientists are working now to adapt 3D printers to function in these conditions. Using otherworldly soil On alien worlds, rather than plastic or metal, 3D printers will use the natural resources found in these environments. But finding the right raw materials is not easy. Habitats on the Moon and Mars must protect astronauts from the lack of air, extreme temperatures, micrometeorite impacts and radiation. Regolith, the fine, dusty, sandlike particles that cover both the lunar and Martian surfaces, could be a primary ingredient to make these dwellings. Think of the regolith on both worlds as alien dirt unlike Earth soil, it contains few nutrients, and as far as we know, no living organisms. But it might be a good raw material for 3D printing. My colleagues began researching this possibility by first examining how regular cement behaves in space. I am now joining them to develop techniques for turning regolith into a printable material and to eventually test these on the Moon. But obtaining otherworldly regolith is a problem. The regolith samples returned from the Moon during the Apollo missions in the 1960s and 70s are precious, difficult if not impossible to access for research purposes. So scientists are using regolith simulants to test ideas. Actual regolith may react quite differently than our simulants. We just dont know. Whats more, the regolith on the Moon is very different from whats found on Mars. Martian regolith contains iron oxide thats what gives it a reddish color but Moon regolith is mostly silicates; its much finer and more angular. Researchers will need to learn how to use both types in a 3D printer. Applications on Earth NASAs Moon-to-Mars Planetary Autonomous Construction Technology program, also known as MMPACT, is advancing the technology needed to print these habitats on alien worlds. Among the approaches scientists are now exploring: a regolith-based concrete made in part from surface ice; melting the regolith at high temperatures, and then using molds to form it while its a liquid; and sintering, which means heating the regolith with concentrated sunlight, lasers or microwaves to fuse particles together without the need for binders. Along those lines, my colleagues and I developed a Martian concrete we call MarsCrete, a material we used to 3D-print a small test structure for NASA in 2017. Then, in May 2019, using another type of special concrete, we 3D-printed a one-third scale prototype Mars habitat that could support everything astronauts would need for long-term survival, including living, sleeping, research and food-production modules. That prototype showcased the potential, and the challenges, of building housing on the red planet. But many of these technologies will benefit people on Earth too. In the same way astronauts will make sustainable products from natural resources, homebuilders could make concretes from binders and aggregates found locally, and maybe even from recycled construction debris. Engineers are already adapting the techniques that could print Martian habitats to address housing shortages here at home. Indeed, 3D-printed homes are already on the market. Meanwhile, the move continues toward establishing a human presence outside the Earth. Artemis III, now scheduled for liftoff in 2027, will be the first human Moon landing since 1972. A NASA trip to Mars could happen as early as 2035. But wherever people go, and whenever they get there, Im certain that 3D printers will be one of the primary tools to let human beings live off alien land. Sven Bilén, Professor of Engineering Design, Electrical Engineering and Aerospace Engineering, Penn State This article is republished from The Conversation under a Creative Commons license. Read the original article.
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If you look at a map of lightning near the Port of Singapore, youll notice an odd streak of intense lightning activity right over the busiest shipping lane in the world. As it turns out, the lightning really is responding to the ships, or rather the tiny particles they emit. Using data from a global lightning detection network, my colleagues and I have been studying how exhaust plumes from ships are associated with an increase in the frequency of lightning. For decades, ship emissions steadily rose as increasing global trade drove higher ship traffic. Then, in 2020, new international regulations cut ships sulfur emissions by 77%. Our newly published research shows how lightning over shipping lanes dropped by half almost overnight after the regulations went into effect. Shipping lanes (top image) and lightning strikes (bottom) near the Port of Singapore. [Image: Chris Wright] That unplanned experiment demonstrates how thunderstorms, which can be 10 miles tall, are sensitive to the emission of particles that are smaller than a grain of sand. The responsiveness of lightning to human pollution helps us get closer to understanding a long-standing mystery: To what extent, if any, have human emissions influenced thunderstorms? Aerosol particles can affect clouds? Aerosol particles, also known as particulate matter, are everywhere. Some are kicked up by wind or produced from biological sources, such as tropical and boreal forests. Others are generated by human industrial activity, such as transportation, agricultural burning and manufacturing. Its hard to imagine, but in a single liter of air about the size of a water bottle there are tens of thousands of tiny suspended clusters of liquid or solid. In a polluted city, there can be millions of particles per liter, mostly invisible to the naked eye. These particles are a key ingredient in cloud formation. They serve as seeds, or nuclei, for water vapor to condense into cloud droplets. The more aerosol particles, the more cloud droplets. Water molecules condense around nuclei to form clouds. [Photo: David Babb/Penn State, CC BY-NC] In shallow clouds, such as the puffy-looking cumulus clouds you might see on a sunny day, having more seeds has the effect of making the cloud brighter, because the increase in droplet surface area scatters more light. In storm clouds, however, those additional droplets freeze into ice crystals, making the effects of aerosol particles on storms tricky to pin down. The freezing of cloud droplets releases latent heat and causes ice to splinter. That freezing, combined with the powerful thermodynamic instabilities that generate storms, produces a system that is very chaotic, making it difficult to isolate how any one factor is influencing them. A view from the International Space Station shows the anvils of tropical thunderstorms as warm ocean air collides with the mountains of Sumatra. [Photo: NASA Visible Earth] We cant generate a thunderstorm in the lab. However, we can study the accidental experiment taking place in the busiest shipping corridor in the world. Ship emissions and lightning With engines that are often three stories tall and burn viscous fuel oil, ships traveling into and out of ports emit copious quantities of soot and sulfur particles. The shipping lanes near the Port of Singapore are the most highly trafficked in the world roughly 20% of the worlds bunkering oil, used by ships, is purchased there. In order to limit toxicity to people near ports, the International Maritime Organization a United Nations agency that oversees shipping rules and security began regulating sulfur emissions in 2020. At the Port of Singapore, the sales of high-sulfur fuel plummeted, from nearly 100% of ship fuel before the regulation to 25% after, replaced by low-sulfur fuels. But what do shipping emissions have to do with lightning? Scientists have proposed a number of hypotheses to explain the correlation between lightning and pollution, all of which revolve around the crux of electrifying a clod: collisions between snowflake-like ice crystals and denser chunks of ice. When the charged, lightweight ice crystals are lofted as the denser ice falls, the cloud becomes a giant capacitor, building electrical energy as the ice crystals bump past each other. Eventually, that capacitor discharges, and out shoots a lightning bolt, five times hotter than the surface of the Sun. We think that, somehow, the aerosol particles from the ships smokestacks are generating more ice crystals or more frequent collisions in the clouds. In our latest study, my colleagues and I describe how lightning over the shipping lane fell by about 50% after 2020. There were no other factors, such as El Nio influences or changes in thunderstorm frequency, that could explain the sudden drop in lightning activity. We concluded that the lightning activity had fallen because of the regulation. The reduction of sulfur in ship fuels meant fewer seeds for water droplet condensation and, as a result, fewer charging collisions between ice crystals. Ultimately, there have been fewer storms that are sufficiently electrified to produce a lightning stroke. Whats next? Less lightning doesnt necessarily mean less rain or fewer storms. There is still much to learn about how humans have changed storms and how we might change them in the future, intentionally or not. Do aerosol particles actually invigorate storms in general, creating more extensive, violent vertical motion? Or are the effects of aerosols specific to the idiosyncrasies of lightning generation? Have humans altered lightning frequency globally? My colleagues and I are working to answer these questions. We hope that by understanding the effects of aerosol particles on lightning, thunderstorm precipitation and cloud development, we can better predict how the Earths climate will respond as human emissions continue to fluctuate. Chris Wright is a fellow in atmospheric science at the Program on Climate Change at the University of Washington. This article is republished from The Conversation under a Creative Commons license. Read the original article.
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