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COVID-19: What is the R number?
R is a way of measuring an infectious disease's capacity to spread.
In just a few short weeks, we've all made the collective journey from pandemic ignoramuses to budding armchair virologists with a decent grasp of once-arcane terms like personal protective equipment, social distancing and "flatten the curve".
But there's one phrase that might still leave a few justifiably scratching their heads: the R number. The coronavirus has one, and governments around the world are keen to see it shrink as much as possible. But what is it?
R refers to the "effective reproduction number" and, basically put, it's a way of measuring an infectious disease's capacity to spread. The R number signifies the average number of people that one infected person will pass the virus to.
The R number isn't fixed, but can be affected by a range of factors, including not just how infectious a disease is but how it develops over time, how a population behaves, and any immunity already possessed thanks to infection or vaccination. Location is also important: a densely populated city is likely to have a higher R than a sparsely peopled rural area.
Because Sars-CoV-2 – to give the novel coronavirus its full honorific – is a new pathogen, scientists at the start of the outbreak were scrambling to calculate its R0, or "R nought": the virus's transmission among a population that has no immunity. Studies on early cases in China indicated it was between 2 and 2.5; more recent estimates have placed it as high as 6.6.
To put these figure in context, says Wired science editor Matt Reynolds, they're worse than seasonal flu, which has an R0 of 1.3, but miles better than measles, whose R0 is between 12 and 18. The kicker, though, is that for each of those diseases we have a vaccine, and so the effective reproduction number – the R – is way below 1.
Why do we need an R of less than 1?
This threshold – an R of 1 – will become increasingly crucial over the next few months. As the UK government explained in the video that accompanied its press briefing on 30 April, an R figure that is even slightly over 1 can lead quickly to a large number of cases thanks to exponential growth.
Here's how that works. Say a disease has an R of 1.5. This may seem like a manageable figure, but a glance at the figures quickly proves that isn't the case. An R of 1.5 would see 100 people infect 150, who would in turn infect 225, who would infect 338. In three rounds of infection, the number of people with the virus would have more than quadrupled to 438. As worldwide cases now exceed 3.5 million, this helps explain why the novel coronavirus was able to rip so quickly among a global population with no previous immunity.Image: BBC
Conversely, an R of less than 1 means that the virus will eventually peter out – the lower the R, the more quickly this will happen. An R of 0.5 means that 100 people would infect only 50, who would infect 25, who would infect 13. As the number of cases drops and ill people either die or recover, the virus will be brought under control – as long as the R can be kept low.
The ongoing battle to reduce R
So an R of 1 and above tends towards exponential growth. An R of below 1 tends towards the end of the outbreak. All we need to do is keep the R below 1. Simple, right?
Not so fast. As stated above, the R value is ever-changing. Thanks to lockdown measures, many governments have been able to push R to below 1. In the UK, chief scientific officer Patrick Vallence said that the nation's R number is currently thought to be between 0.6 and 0.9, though it varies regionally and in London could be as low as 0.5 to 0.7.
This was only achieved, however, thanks to a heroic, unprecedented series of adjustments which have brought our lives and our economies to a juddering halt – and all of this to produce an R of 0.6 to 0.9. This doesn't give us a huge amount of leeway.
Lockdown helped drop Germany's R down to about 0.7 in early April, but researchers at the Robert Koch Institute in Berlin said it had recently increased back to 0.9, before sinking again to 0.75. Even within lockdown, if people start losing patience with restrictions or need to go out to work, R could quickly rise again.
Another difficulty that scientists and policymakers are facing is that it's still not entirely clear how much of a role each measure plays. Is shutting schools doing the heavy lifting, or restricting access to shops? How much of a boost could wearing masks provide?
As governments tentatively ease lockdown restrictions around the world, they will be monitoring R very carefully for signs of a sudden jump. If R sneaks above 1 even a fraction, it could trigger a damaging second wave of the virus.
Once R is consistently low and the number of cases is manageable, governments can implement more precise measures to restrict R, such as contact-tracing and location-tracking apps – approaches that paid dividends when introduced early on in nations such as South Korea and Singapore.
There are a number of ways to calculate R, as Wired notes. One is by monitoring hospitalisation and death figures to get a sense of how many people have the virus – but the problem with this is that, since the virus's incubation period is so long, it only gives an accurate picture of a few weeks ago. To check transmission rates in a more accurate way, scientists at Imperial College London in the UK have started testing randomised 25,000 groups of the population to see how many are ill.
It's important to note that R isn't the only key measure in assessing the impact of this pathogen, says the BBC. Another crucial yardstick is the number of cases of COVID-19, the disease caused by Sars-CoV-2. If we have a large number of cases and an R of 1 or just below, that still equates to a large number of infections – so ideally we need to restrict both R and bring down the number of cases at the same time.
An additional key measure to look out for is the number of ICU beds available in any given country, since this will have a big effect on mortality rate.
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She met mere mortals with and without the Vatican's approval.
- For centuries, the Virgin Mary has appeared to the faithful, requesting devotion and promising comfort.
- These maps show the geography of Marian apparitions – the handful approved by the Vatican, and many others.
- Historically, Europe is where most apparitions have been reported, but the U.S. is pretty fertile ground too.
The divine is supernatural, but religion is very much of this world. The way people worship even has an impact on their physical surroundings. Here's a telltale sign that you're in Catholic country: chapels, shrines and grottoes dot the roadside. The latter are replicas of the cave in southern France where the Virgin Mary appeared to a local peasant girl in the early 19th century.
Those Marian apparitions themselves are another peculiar point of contact between faith and the world. Typically, they happen in times of crisis to young children from a humble background. They are often the only ones able to see the apparition. The visitations sometimes reoccur over a prolonged period. If the Virgin speaks to those who can observe her, it is to ask for a chapel or church to be built, to implore the faithful to be more devout, and/or to offer warnings for the future. Witnesses are often able to report in great detail on the dress and attributes of the apparition, but mostly there is no direct contact between the Virgin and the observers.
What is a Marian apparition?
Marian apparitions are generally associated with Catholicism, which has great devotion for Mary, the mother of Jesus. Despite her being the mother of Christ, the church does not consider Mary to be divine herself. According to Catholic doctrine, the age of public revelation ended when John, the last apostle, died around the year 100 AD. Marian apparitions therefore are 'private revelations', illuminating aspects of faith but never revealing new ones.
Apparitions often are the object of ridicule. Some may be fraudulent. Most do not get an official church approval, neither from the local bishop or from the Vatican. Unrecognized apparitions may thus lead to schisms with the official church. The visionary and their followers may decide to found their own independent movement or join existing sects. Either path is usually characterized by a traditionalist approach to the faith, often rejecting the innovations of the Second Vatican Council.
A world map of Marian apparitions
Outside Europe, the U.S. leads the world in Marian apparitions - all but one unrecognized by the Catholic church.
The Virgin Mary tends to appear in regions mostly inhabited by Catholics.
These maps, produced by National Geographic, show the geography of Marian visitations, in Europe and in the rest of the world.
- Crosses show where the Virgin Mary appeared to a future saint.
- Yellow dots mark visitations related by tradition (but not attested by the Vatican).
- Blue dots denote more recent, but as yet unconfirmed apparitions.
- Green dots signify visions approved as 'worthy of faith', but not supernatural.
- Red dots mean a local bishop has 'approved' the apparition as genuine.
- Larger red dots (for named apparitions) mark those that have also been recognized by the Vatican.
In Europe, the Virgin's favorite destinations appear to be Italy and France, followed by southern Germany (i.e. the Catholic half) and Belgium. Considering the traditional hold of the faith on Spain and Poland, the number of Marian apparitions is relatively small. A fair number in western Ukraine, but none in eastern Germany. A handful in Hungary, almost none in the Balkans (Medjugorje being the most notable exception). Ireland out-Marys England, and Scandinavia is entirely free of Holy Mothers.The U.S. leads the rest of the world in the number of apparitions, although most are unrecognized. Two apparitions in Africa and one in Mexico are officially recognized by the Vatican. Here's an overview of all Vatican-approved apparitions of the Virgin Mary.
Our Lady of Knock, Ireland
Part of the new mosaic, unveiled at the Basilica of Knock in February 2016.
On 21 August 1879, the Virgin Mary, Saint Joseph and Saint John the Evangelist appeared to two women (both called Mary) outside a church in the village of Knock, County Mayo, Ireland.
They were joined by other witnesses, who also saw a cross and a lamb on a small altar behind the three figures. A witness further away described the scene as englobed in golden light.
The apparition lasted for nearly two hours, during which the witnesses – standing in the pouring rain – recited the rosary. Meanwhile, the ground around the apparition remained entirely dry.
A church commission judged the apparition 'trustworthy'. Knock developed into a pilgrimage site. The apparition occurred at a time of agricultural strife and cultural crisis in Ireland, when the common language shifted from Gaelic to English.
That may explain why the apparition remained silent: the oldest witness knew no English, while the youngest knew no Gaelic. On 13 May 2017, that youngest witness, John Curry, was reinterred in Old St Patrick's in Manhattan after his remains had been identified in an unmarked grave on Long Island.
Our Lady of Pontmain, France
Interior of the basilica of Pontmain. The blue color effect is created by the tinted windows.
Image: Michel GILE/Gamma-Rapho via Getty Images
On 17 January 1871, at the height of the Franco-Prussian War, 12-year-old Eugène Barbedette looked out at the night sky over Pontmain and saw a beautiful woman wearing a blue gown studded with stars and a black veil under a golden crown.
His 10-year-old brother also saw the apparition, but their parents, and other adults, saw nothing. Two other children described the apparition in the same detail as the two brothers. Adults could only see a triangle of stars.
After three hours, the apparition vanished. That same evening, Prussian forces inexplicably abandoned their advance towards the town. The children who saw the apparition later became priests and nuns.
Pontmain is a place of pilgrimage, also from Germany. Bob Hope and his wife donated funds for a chapel dedicated to Our Lady of Hope of Pontmain at the National Shrine of the Immaculate Conception in Washington DC.
Our Lady of the Miraculous Medal, France
Medal of the Immaculate Conception (a.k.a. 'Miraculous Medal'), created by Saint Catherine Labouré in response to a request from the Blessed Virgin Mary.
Image: Xhienne, CC BY-SA 3.0
On 19 July 1930, a voice woke up the nun Catherine Labouré calling her to chapel, where the Virgin Mary told her that "times are evil in France and the world" and instructed Catherine to produce medallions that would confer graces on those that wore them.
The medallions proved very popular. Inscribed with the slogan 'Ô Marie conçue sans péché, priez pour nous qui avons recours à vous' ('O Mary, conceived without sin, pray for us who have recourse to thee'), they were influential in the Vatican's promulgation, in 1854, of the dogma of the Immaculate Conception.
Sister Catherine spent the rest of her life caring for the sick and elderly. Her body, now encased in glass in Paris, was discovered to be incorrupt. She was canonized in 1947. Pope John Paul II used a variation of the medallion's image as his coat of arms.
Our Lady of the Golden Heart, Belgium
The Chapel of Our Lady in Beauraing.
Image: Jean-Pol Grandmont, CC BY 3.0
Between November 1932 and the next January, the Virgin Mary appeared a total of 33 times to five children between 9 and 15 in the small Belgian town of Beauraing.
The lady, dressed in a long white robe, said she was the Immaculate Virgin, requested that a chapel be built at the site of her apparition, and asked the children – and everybody – to pray. During one of the last visitations, she revealed her golden heart.
Virgin of the Poor, Belgium
The miraculous spring of Our Lady of Banneux.
Image: Johfrael, CC BY-SA 3.0
A few days after the Virgin's last apparition in Beauraing, she appeared in the nearby town of Banneux. Between 15 January and 2 March 1933, 12-year-old Mariette Beco saw a lady in a white gown and blue sash who claimed to be the Virgin of the Poor, and stated: "Believe in me and I will believe in you."
The Virgin asked Mariette to put her hands in a small spring, ordaining it for healing for all nations. A chapel is built where the Virgin requested it. The Marian apparition of Banneux carries two titles: Our Lady of the Poor and Queen of Nations.
Mariette was made fun of, even by her own grandmother and aunt. Others tauntingly called her 'Bernadette', after the French girl who had visions of Mary in Lourdes. Mariette married and led a quiet life. In 2008, three years before her death, she said: "I was just delivered the message. The messenger is of no importance."
Our Lady, Help of Christians, Czech Republic
The basilica at Filipov.
Image: Kmenicka, CC BY 3.0
At four in the morning on 13 January 1866, the Virgin Mary appeared at the sickbed of Magdalena Kade. Mary, dressed in white and wearing a golden tiara, pronounced Magdalena healed from her long illness. Many miraculous healings were subsequently reported. A church (later elevated to basilica-status) and convent were built on the location, which is sometimes called the 'Lourdes of Bohemia'.
The miraculous nature of Magdalena's sudden cure was questioned by her contemporaries. In 2008, German journalist Kerstin Schneider – a distant relative of Magdalena Kade – draws a parallel with the clinical history of her great aunt Lina Marie Schöbel, a schizophrenic who all of a sudden declared she was 'Jesus', and who was exterminated by the Nazis for being insane.
Our Lady of Gietrzwald, Poland
The inside of the basilica at Gietrzwald, the 'Polish Fatima'.
Image: Mazaki, CC BY-SA 4.0
On 27 June 1877, a 'Bright Lady' showed herself to 13-year-old Justyna Szafrynska and a day later also to her friend Barbara Samulowska. The lady appeared over the maple tree in front of the church, seated on a throne with the infant Jesus on her lap, surrounded by angels.
She told the girls she was the Blessed Virgin Mary of the Immaculate Conception, and she wished them to say the rosary every day. The Virgin blessed a spring, said the sick would be healed and asked that they too pray the rosary.
Asked what happens to people who swear falsely, the Holy Mother said that "Such person is not deserving to go to Heaven (and) is induced to do it by Satan".
The Prussian authorities saw the apparitions as an expression of Polish nationalism and sought to suppress the event, even imprisoning the local parish priest.
Our Lady of Lezajsk, Poland
Icon of the Virgin of Lezajsk.
In 1578, woodcutter Thomas Michalek saw a bright light in the forest. It was the Virgin Mary, who asked him to alert the authorities to build a church on the site. Thomas was scared and did nothing.
The Virgin then reappeared and instructed him to take action. Which he did – but he was not believed. In fact, the local curate took him to court. After the curate's death, a small chapel was finally built.
By the way, Lezajsk is also a place of pilgrimage for Jews, who come to visit the tomb of 18th-century rabbi Elimelech, one of the founders of the Hasidic movement.
Our Lady of Šiluva, Lithuania
Lithuanian pilgrims on the way to Šiluva.
Image: CD, CC BY-SA 3.0
In the summer of 1608, some children tending sheep reported seeing a beautiful lady holding a baby on the spot where a church had stood, and she was weeping. The children returned the next day with some villagers, including a Calvinist minister. They all saw the lady as well.
A new Catholic church was built on the site of the old one, and eventually replaced by a much larger one to accommodate the multitudes of pilgrims – now the Basilic of the Nativity of Mary. The Chapel of the Apparition, built over the rock where the Virgin appeared, has the tallest steeple in Lithuania. Pilgrims kiss the rock itself, which is accessible under the chapel's altar.
For its devotion to the Virgin, Pope Pius XI entitled Lithuania as Terra Mariana ('Maryland'). Until World War II, processions of pilgrimage to Šiluva would start in towns all over Lithuania. Our Lady of Šiluva is the patroness of those who have lapsed from the Catholic faith, and of those who pray on their behalf.
Our Lady of La Salette, France
Sanctuary of Notre-Dame de la Salette.
Image: Fphoto, CC BY-SA 4.0
On 19 September 1846, two cowherders, Maximin Giraud (11) and Mélanie Calvat (15), reported seeing a 'beautiful lady' in the mountains, wearing a pearl-studded white robe and a gold apron. Her face buried in her hands, she was weeping bitterly. She spoke to them, first in French, then in the local language, Occitan.
The apparition urged people to respect the seventh day and the name of God, sorrowfully threatening punishment (including a scarcity of potatoes). She asked that her message be spread to the world. Each child received a secret, after which the lady vanished.
Some observers at the time considered the apparition at La Salette a 'pious fraud'. Two priests specifically accused Constance Saint-Ferréol de La Merlière, a former nun, of having 'dressed up' as the Mother of God, inculcating the two credulous teenagers with her own religious agenda. Mademoiselle de La Merlière sued the priests for defamation – and lost, twice.
In 1852, the Missionaries of Our Lady of La Salette were founded. The order still has missionaries serving in many countries. The shrine remains popular with traditionalist believers and the Charismatic Movement within the Catholic church.
Our Lady of Happy Meetings, France
The Virgin appears to Benoîte.
Image: AntonyB, CC BY-SA 3.0
In May 1664, Benoîte Rencurel, a 17-year-old shepherdess in southeastern France, saw an apparition of St Maurice, a third-century martyr greatly revered in her home region. He warned her that locals eyed her flock and counseled that she should go to a nearby valley, where she would see the Virgin Mary.
In a grotto in the Valley of Kilns, she discovered Mary, holding baby Jesus. The Virgin directed Benoîte to go to the village of Laus, where she was instructed to build a chapel where sinners would be converted and the Virgin promised to appear often.
Some of the pilgrims to Laus have themselves become saints, including Eugene de Mazenod, founder of the Oblates of Mary Immaculate. The Marian apparitions at Laus lasted until 1718. Despite their antiquity, the apparitions of Our Lady of Laus were recognized by the Holy See only in 2008.
Our Lady of Fátima, Portugal
Crowds at the Sanctuary of Our Lady of Fátima on 12 May 2017 for the centennial of the first apparition.
Image: Centro Televisivo Vaticano, CC BY 3.0
Between 13 May to 13 October 1917, 'a lady more brilliant than the sun' appeared six times to three Portuguese shepherd children, Lúcia dos Santos and her cousins Francisco and Jacinta Marto.
The lady asked them to devote themselves to the Holy Trinity and to pray the Rosary every day; prayer would end the Great War then still raging. She also showed them a vision of hell and entrusted them with three secrets.
The children's visions drew thousands of visitors and upset the political balance in the country, with a young, anticlerical republic fighting off a strong conservative reaction. The children were even briefly jailed, and variously ordered to reveal the secrets or admit that they had lied. The local administrator even threatened that he would boil them one by one in a pot of oil.
At the Virgin's last appearance, many of the up to 100,000 visitors reported a 'Miracle of the Sun': multicolored light and erratic movement from the sun. Others saw nothing out of the ordinary.
As predicted by the Virgin, Francisco and Jacinta died soon afterward, in the Spanish Flu pandemic that started in 1918. Lucia became a nun, and sporadically saw the Virgin again later in life, as well as Jesus. She died in 2005, aged 97.
Already in the first few years after the events, Fátima attracted millions of visitors. Our Lady of Fátima was popular among anticommunist and traditionalist Catholics. Pope John Paul II credited Our Lady of Fátima with saving his life in the attempt on his life of 13 May 1981 – the Feast of Our Lady of Fátima. The Pope donated the bullet that wounded him to the Sanctuary at Fátima. Fátima currently is one of the world's most popular centers of pilgrimage.
Our Lady of Lourdes, France
Religious souvenirs ('bondieuseries') in Lourdes.
Image: Jean-Noël Lafargue
On 11 February 1858, 'a petite damsel' spoke to 14-year-old Bernadette Soubirous in the grotto of Massabielle about a mile from the southern French town of Lourdes. The lady, who appeared 17 further times, revealed herself to be Our Lady of the Immaculate Conception and asked that a chapel be built on that spot.
Bernadette's vision has similarities to that of Anglèze de Sagazan, a 12-year-old shepherdess who in the 16th century saw the Virgin at a spring in nearby Garaison. Pilgrimages to Garaison were soon eclipsed by those to Lourdes.
The Virgin revealed a spring to Bernadette and directed pilgrims to drink from and wash in it. The water, provided free of charge to pilgrims, is a popular memento of a trip to Lourdes. Some have claimed to have been cured by it.
Millions of pilgrims, many suffering from illnesses, travel to Lourdes each year. Lourdes now is a major pilgrimage site, and has more hotel rooms than any other place in France, with the exception of Paris.
The Lourdes Bureau Médical has documented around 70 miraculous healings at the site. Bernadette was canonized as a saint in 1933. The apparition at Lourdes is also recognized by the Anglican church, which has its own Marian Shrine at Lourdes.
Our Lady of Zion, Italy
Bust of Marie-Alphones Ratisbonne at the Ratisbonne Monastery in Jerusalem.
Image: Gilabrand, CC BY 3.0
On 20 January 1842 while visiting Rome, Marie-Alphonse Ratisbonne, an anti-Catholic Jew, had a vision of the Virgin Mary. He converted to Catholicism and began a ministry for the conversion of the Jews.
Together with his brother, who had converted and become a priest years before, he founded the Sisterhood of Our Lady of Sion. Ratisbonne eventually joined the priesthood himself and becomes a Jesuit.
In 1855, he moved the sisters to Jerusalem, where he founds the Convent of Ecce Homo and the Convent of St John.
Mother of the Word, Rwanda
Joyous entry of Our Lady of Kibeho in the parish of St Jean Bosco in Rango.
Image: Paroisse de Rango
On 28 November 1981, the Virgin Mary first appeared to Alphonsine Mumureke, and over the next few years also to two other pupils at Kibeho College, a girls' school in southwestern Rwanda.
She identified herself as Nyina wa Jambo ('Mother of the Word' in Kinyarwanda) or Umubyeyi W'Imana ('Mother of God') and asked everyone to pray to prevent a terrible war – perhaps a premonition of the 1994 Rwandan Genocide, as tensions between Hutus and Tutsis were already rising back then.
The three women reported going on 'mystic voyages' with the Virgin during their individual visions, which could last for hours. Inexplicably, the women seemed to acquire so much weight during their visions that they could not be lifted off the ground.
Four other people in Kibeho reported apparitions – one met Christ in a beanfield – but these have not been approved by the Holy See.
The apparition was named 'Our Lady of Sorrows' two years before the start of the genocide in 1994. Marie Claire Mukangango, one of the three young women receiving visions in the 1980s, was among those killed, together with her family, in a massacre in Kibeho, in April 1995.
Our Lady of Zeitoun, Egypt
Apparition of the Virgin Mary on the roof of the Coptic church in Zeitoun.
Image: Public domain
On 2 April 1968, a Muslim bus driver thought he saw a lady standing on top of St Mary's Coptic Church in Zeitoun, near Cairo and thought she was about to commit suicide. The police were called, but the gathered crowd quickly identified the figure as the Virgin Mary.
After a few minutes, the figure vanished. The lady returned a week later, again for a few minutes. After that, apparitions occurred up to several times a week, until 1971. The Vatican sent an envoy but left the investigation to the Coptic authorities.
Uniquely, the location of the apparition has a historical link to the Virgin Mary, at least according to Coptic tradition: It is said to be one of the places where the Holy Family rested on their flight from Bethlehem to Egypt.
Also unlike most other apparitions, the Zeitoun Virgin was seen by huge crowds – estimates vary from 250,000 to even millions, over the course of the four years the phenomenon lasted. Included were many Muslims, Egyptian president Nasser among them (Mary features prominently in the Quran as well). The phenomenon was also captured on camera.
Skeptics nevertheless see the apparitions at Zeitoun as a case of mass hysteria in a time of crisis; following Egypt's defeat by Israel in the war of 1967, people felt let down by modernity and turned to religion.
Our Lady of Guadalupe, Mexico
The original image of the Virgin of Guadalupe.
Image: Public domain
On 9 December 1531, the Virgin appeared to Juan Diego, a native peasant, on the Hill of Tepeyac near Mexico City. Speaking to him in the local Nahuatl language, she asked for a church to be built on the site.
Juan Diego reported the sighting to the archbishop of Mexico, but he didn't believe him and asked for a miraculous sign. The Virgin healed Juan Diego's uncle and appeared to him as well, instructed Juan Diego to pick Castilian roses on top of the usually barren Tepeyac Hill, and transformed his cloak into an image of the Virgin.
A few days later, the cloak was displayed in a hastily erected chapel. Miracles started occurring almost immediately. Our Lady of Guadalupe became Mexico's most popular religious symbol, and in the 19th century a rallying point for Mexico's independence struggle against Spain.
Despite the fact that Juan Diego was canonized in 2002, some Catholic scholars doubt he ever existed. According to them, the cult of Guadalupe was designed to increase Catholic devotion among indigenous Mexicans. The image on the cloak, they point out, resembles contemporary Spanish artwork. Many believers nevertheless ascribe miraculous qualities to the cloak, which is exhibited in the Basilica, in a climate-controlled, bullet-proof casing.
Although Nahuatl origins have been proposed, it seems likely that the name Guadalupe, which became attached to the apparition, is a Spanish reference. Extremadura, the Spanish region where conquistador Hernán Cortés was born, has its own cult of Our Lady of Guadalupe, centered on a statue said to be carved by St Luke the Evangelist.
However, for native Mexicans, Our Lady of Guadalupe recalled Tonantzín, an Aztec earth goddess and serpent destroyer, whose temple previously stood on the same hill where the Basilica is now.
Our Lady of Guadalupe is the patron saint of Mexico, of the Americas, and of the unborn – and thus also a symbol for the Pro-Life movement. The Basilica of Our Lady of Guadalupe in Mexico City is the world's most visited Catholic shrine, receiving millions of pilgrims every year.
Of the 386 claims of Marian apparitions in the 20th century, eight were approved and 79 rejected by the Catholic church, with no definitive verdict on the rest. In 2010, bishop David L. Ricken of Green Bay recognised the apparition of the Virgin to Adele Brise in 1859. Our Lady of Good Help, whose shrine is located in Champion, Wisconsin, is the first Marian apparition approved by the Church in the U.S. (although not yet by the Vatican).
The number of apparitions peaked in 1954 but has been on a steady decline since the mid-1980s, perhaps due to a lack of underage shepherds roaming the countryside.
Here's one Marian apparition you've probably never considered: it's on the flag of the European Union. Officially adopted by the (then) European Economic Community in 1985, the EU flag shows a circle of 12 gold stars on an azure background. It had originally been the symbol of the Council of Europe, who adopted it in 1955 on December 8, the feast of Mary's Immaculate Conception.
Konrad Adenauer (Germany), Robert Schumann (France) and Alcide de Gasperi (Italy) were not just some of the major driving forces behind early European integration, they were also devout Catholics. In 1956, the Council of Europe donated a stained-glass window to Strasbourg Cathedral, showing the Virgin surrounded by twelve stars on a blue field.
European flags fluttering in front of the Berlaymont building in Brussels.Image: Thijs ter Haar, CC BY 2.0
Arsène Heitz, designer of the 12-starred flag, credited a passage in chapter 12 of the Book of Revelation as a source for the image. It refers to a woman "clothed with the sun, with the moon under her feet and on her head a crown of twelve stars."
And that is why the number of stars on the flag does not refer to the number of member states (28 now, 27 after Brexit), but is in fact an emblem of Catholic devotion to Mary – despite the fact that the European Union is a non-religious entity.
Strange Maps #955
Got a strange map? Let me know at firstname.lastname@example.org.
Since 1957, the world's space agencies have been polluting the space above us with countless pieces of junk, threatening our technological infrastructure and ability to venture deeper into space.
- Space debris is any human-made object that's currently orbiting Earth.
- When space debris collides with other space debris, it can create thousands more pieces of junk, a dangerous phenomenon known as the Kessler syndrome.
- Radical solutions are being proposed to fix the problem, some of which just might work. (See the video embedded toward the end of the article.)
In 1957, the Soviet Union launched a human-made object into orbit for the first time. It marked the dawn of the Space Age. But when Sputnik 1's batteries died and the aluminum satellite began lifelessly orbiting the planet, it marked the end of another era: the billions of years during which space was pristine.
Today, the space above Earth is the world's "largest garbage dump," according to NASA. It's littered with 8,000 tons of human-made junk, called space debris, left by space agencies over the past six decades.
The U.S. now tracks more than 25,000 pieces of space junk. And that's only the debris that ground-based radar technologies can track. The U.S. Space Surveillance Network estimates there could be more than 170 million pieces of space debris currently orbiting Earth, with the majority being tiny fragments smaller than 1 mm.
Space debris: Trashing a planet
Space debris includes all human-made objects, big and small, that are orbiting Earth but no longer serve a useful function. A brief inventory of known space junk includes: a spatula, a glove, a mirror, a bag filled with astronaut tools, spent rocket stages, stray bolts, paint chips, defunct spacecraft, and about 3,000 dead satellites — all of which are orbiting Earth at speeds of roughly 18,000 m.p.h.
By allowing space debris to accumulate unchecked, we could be building a prison that keeps us stranded on Earth for centuries.
Most space junk is floating in low Earth orbit (LEO), the region of space within an altitude of about 100 to 1,200 miles. LEO is also where most of the world's 3,000 satellites operate, powering our telecommunications, GPS technologies, and military operations.
"Millions of pieces of orbital debris exist in low Earth orbit (LEO) — at least 26,000 the size of a softball or larger that could destroy a satellite on impact; over 500,000 the size of a marble big enough to cause damage to spacecraft or satellites; and over 100 million the size of a grain of salt that could puncture a spacesuit," wrote NASA's Office of Inspector General Office of Audits.
If LEO becomes polluted with too much space junk, it could become treacherous for spacecraft, threatening not only our modern technological infrastructure, but also humanity's ability to venture into space at all.
By allowing space debris to accumulate unchecked, we could be building a prison that keeps us stranded on Earth for centuries.
An outsized problem
Space debris of any size poses grave threats to spacecraft. But tiny, untrackable micro-debris presents an especially dreadful problem: A paint fragment chipped off a spacecraft might not seem dangerous, but it careens through space at nearly 10 times the speed of a bullet, packing enough energy to puncture an astronaut's suit, crack a window of the International Space Station, and potentially destroy satellites.
Impacts with space debris are common. During the Space Shuttle era, NASA replaced an average of one to two shuttle windows per mission "due to hypervelocity impacts (HVIs) from space debris." To be sure, some space debris are natural micrometeoroids. But much of it is human-made, like the fragment that struck the starboard payload bay radiator of the STS-115 flight in 2006.
"The debris penetrated both walls of the honeycomb structure, and the shock wave from the penetration created a crack in the rear surface of the radiator 6.8 mm long," NASA wrote. "Scanning electron microscopy and energy dispersive X-ray detection analysis of residual material around the hole and in the interior of the radiator shows that the impactor was a small fragment of circuit board material."
The European Space Agency notes that any fragment of space debris larger than a centimeter could shatter a spacecraft into pieces.
Impact chip on the ISSESA
To dodge space junk, the International Space Station (ISS) has to conduct "avoidance maneuvers" a couple times every year. In 2014, for example, flight controllers decided to raise the ISS's altitude by half a mile to avoid collision with part of an old European rocket in its orbital path.
NASA has strict guidelines for how it decides to perform these maneuvers.
"Debris avoidance maneuvers are planned when the probability of collision from a conjunction reaches limits set in the space shuttle and space station flight rules," NASA wrote. "If the probability of collision is greater than 1 in 100,000, a maneuver will be conducted if it will not result in significant impact to mission objectives. If it is greater than 1 in 10,000, a maneuver will be conducted unless it will result in additional risk to the crew."
These precautionary measures are becoming increasingly necessary. In 2020, the ISS had to move three times to avoid potential collisions. One of the latest close-calls came with such little warning that astronauts were instructed to take shelter in the Russian segment of the space station, in order to be closer to their Soyuz MS-16 spacecraft, which serves as an escape pod in case of an emergency.
The Kessler syndrome
The hazards of space debris grow exponentially over time. That's because of a problem that NASA scientist Donald J. Kessler outlined in 1978. The so-called Kessler syndrome states that as space becomes increasingly packed with spacecraft and debris, collisions become more likely. And because each collision would create more debris, it could trigger a chain reaction of collisions — potentially to the point where near-Earth space becomes a shrapnel field through which safe travel is impossible.
A paint fragment chipped off a spacecraft might not seem dangerous, but it careens through space at nearly 10 times the speed of a bullet, packing enough energy to puncture an astronaut's suit, crack a window of the International Space Station, and potentially destroy satellites.
The Kessler syndrome may already be playing out. Perhaps it began with the first known case of a spacecraft being severely damaged by artificial space debris, which occurred in 1996 when the French spy satellite Cerise was struck by a piece of an old European Ariane rocket. The collision tore off a 13-foot segment of the satellite.
The next major space debris incident occurred in 2007 when China conducted an anti-satellite missile test in which the nation destroyed one of its own weather satellites, triggering international criticism and creating more than 3,000 pieces of trackable space debris, most of which was still in orbit ten years after the explosion.
Then, in 2009, an unexpected collision between communications satellites — the active Iridium 33 and the defunct Russian Cosmos-2251 — produced at least 2,000 large fragments of space debris and as many as 200,000 smaller pieces, according to NASA. About half of all space debris currently orbiting Earth came from the Iridium-Cosmos collision and China's missile test.
There's more. Russia's BLITS satellite was spun out of its orbital path in 2013 after being struck by a piece of space debris suspected to have come from China's 2007 missile test; the European Space Agency's Copernicus Sentinel-1A satellite was struck by a tiny particle in 2016; and a window of the ISS was hit by a small fragment that same year.
As nations and private companies plan to send more satellites into orbit, collisions and impacts could soon become more common.
The promise and peril of satellite mega-constellations
Space organizations have recently begun launching satellites into low Earth orbit at an unprecedented pace. The goal is to create "mega-constellations" of satellites that provide high-quality internet access to virtually all parts of the planet.
Internet-providing satellites have existed for years, but they're typically expensive and provide slower service than land-based internet infrastructure. That's mainly because it can take a relatively long time for a signal to travel from the satellite to the user due to the high altitudes at which many of these satellites float above us in geostationary orbit.
China and companies like SpaceX, OneWeb, and Amazon aim to solve this problem by launching thousands of satellites into lower orbits in order to reduce signal latency, or the time it takes for the signal to travel to and from the satellite. But some space experts worry satellite mega-constellations could create more space debris.
"We face entirely new challenges as hundreds of satellites are launched every month now — more than we used to launch in a year," Thomas Schildknecht of the International Astronomical Union said at a European Space Agency conference in April. "The mega-constellations are producing huge risks of collisions. We need more stringent rules for traffic management in space and international mechanisms to ensure enforcement of the rules."
A 2017 study funded by the European Space Agency found that the deployment of satellite mega-constellations into low Earth orbit could increase the number of catastrophic collisions by 50 percent. Still, it remains unclear whether sending more satellites into space will necessarily cause more collisions.
SpaceX, for example, claims that Starlink satellites aren't at significant risk of collision because they're equipped with automated collision-avoidance propulsion systems. However, this system seemed to fail in 2019 when a Starlink satellite had a close call with a European science satellite named Aeolus. The company later said it had fixed the bug.
A batch of 60 Starlink test satellites stacked atop a Falcon 9 rocket.SpaceX
Currently, there are no strict international rules governing the deployment and management of satellite mega-constellations. But there are some international efforts to curb space debris risks.
The most concerted effort is the Inter-Agency Space Debris Coordination Committee (IADC), a forum that comprises 13 of the world's space agencies, including those of the U.S., Russia, China, and Japan. The committee aims "to exchange information on space debris research activities between member space agencies, to facilitate opportunities for cooperation in space debris research, to review the progress of ongoing cooperative activities, and to identify debris mitigation options."
The IADC's Space Debris Mitigation Guidelines list three broad goals:
1. Preventing on-orbit break-ups
2. Removing spacecraft from the densely populated orbit regions when they reach the end of their mission
3. Limiting the objects released during normal operations
But even though the world's space agencies recognize the gravity of the space debris problem, they're reluctant to act because of an incentives-based dilemma.
Space debris: A classic tragedy of the commons
Space debris is everyone's problem, but no one entity is obligated to solve it. It's a tragedy of the commons — an economic scenario in which individuals with access to a shared and scarce resource (space) act in their own best interest (spend the least amount of money). Left unchecked, the shared resource is vulnerable to depletion or corruption.
For example, the U.S. by itself could develop a novel method for removing space debris, which, if successful, would benefit all organizations with assets in space. But the odds of this happening are slim because of a game-theoretical dilemma.
"[In space debris removal] each stakeholder has an incentive to delay its actions and wait for others to respond. This makes the space debris removal setting an interesting strategic dilemma. As all actors share the same environment, actions by one have a potential immediate and future impact on all others. This gives rise to a social dilemma in which the benefits of individual investment are shared by all while the costs are not. This encourages free-riders, who reap the benefits without paying the costs. However, if all involved parties reason this way, the resulting inaction may prove to be far worse for all involved. This is known in the game theory literature as the tragedy of the commons."
Similar to trying to curb climate change, there's no clear answer on how to best incentivize nations to mitigate space debris. (For what it's worth, the game theoretical model in the 2018 study found that a centralized solution — e.g., one where a single actor makes decisions on mitigating space debris, perhaps on behalf of a multinational coalition — is less costly than a decentralized solution.)
Although space organizations have been slow to act, many have been exploring ways to remove space junk from orbit and prevent new debris from forming.
Cleaning up space debris
Space organizations have proposed and experimented with many ways to remove debris from space. Although the techniques vary, most agree on strategy: get rid of the big stuff first.
That's because collisions involving large objects would create lots of new debris. So, removing big debris first would simultaneously clean up low Earth orbit and slow down the phenomenon of cascading collisions described by the Kessler syndrome.
To clean up low Earth orbit, space organizations have proposed using:
- Electrodynamic tethers: In 2017, the Japanese Aerospace Exploration Agency attempted to remove space debris by outfitting a cargo ship with an electrodynamic tether — essentially a fishing net made of stainless steel and aluminium. The craft then tried to "catch" space debris with the aim of dragging it into lower orbit, where it would eventually crash to Earth. The experiment failed.
- Ultra-thin nets: NASA's Innovative Advanced Concepts program has funded research for a project that would deploy extremely thin nets designed to wrap around space debris and drag them down to Earth's atmosphere.
- "Laser brooms": Since the 1990s, space researchers have proposed using ground-based lasers to strategically heat one side of a piece of space debris, which would change its orbit so that it re-enters Earth's atmosphere sooner. Because the laser systems would be based on Earth, this strategy could prove to be relatively affordable.
- Drag sails: As a relatively passive way to accelerate the de-orbit of space junk, NASA and other space organizations have been exploring the viability of attaching sails to space junk that would help guide debris back to Earth. These sails could either be packed within new satellites, to be deployed once the satellites are no longer useful, or attached to existing space junk.
Illustration of Brane Craft Phase II, which would use thin nets to capture space debris.Siegfried Janson via NASA
But perhaps one of the most promising solutions for space debris is the ESA-funded ClearSpace-1 mission. Set to launch in 2025, ClearSpace-1 intends to be the first mission that successfully removes space debris from orbit. The goal is to launch a satellite into orbit and rendezvous with the upper stage of Europe's Vega launcher, which was left in space after a 2013 flight.
ClearSpace-1 satellite using its robotic arm to capture space debrisClearSpace-1
Once the satellite meets up with the debris, it will try to capture the junk with a robotic arm and then perform a controlled atmospheric reentry. The task will be challenging, in part because space junk tumbles as it flies above Earth, meaning the satellite will have to match its movements in order to safely capture it.
Freethink recently spoke to the ClearSpace-1 team to get a better understanding of the mission and its challenges.
Catching the Most Dangerous Thing in Space Freethink via youtube.com
But not all space debris removal strategies center on technology. A 2020 paper published in PNAS argued that imposing taxes on each satellite in orbit would be the most effective way to clean up space. Called "orbital use fees," the plan would charge space organizations an annual fee of roughly $235,000 per each satellite that's in orbit. The fee would, in theory, incentivize nations and companies to declutter space over time.
The main hurdle of orbital-use fees is getting all of the world's space organizations to agree to such a plan. If they do, it could help eliminate the tragedy of the commons aspect of space debris and potentially quadruple the value of the space industry by 2040.
"The costly buildup of debris and satellites in low-Earth orbit is fundamentally a problem of incentives — satellite operators currently lack the incentives to factor into their launch decisions the collision risks their satellites impose on other operators," the researchers wrote. "Our analysis suggests that correcting these incentives, via an OUF, could have substantial economic benefits to the satellite industry, and failing to do so could have substantial and escalating economic costs."
No matter the solution, cleaning up space debris will be a complex and expensive challenge that requires a coordinated, international effort. If the global community wants to maintain modern technological infrastructure and venture deeper into space, conducting business as usual isn't an option.
"Imagine how dangerous sailing the high seas would be if all the ships ever lost in history were still drifting on top of the water," Jan Wörner, European Space Agency (ESA) director general, said in a statement. "That is the current situation in orbit, and it cannot be allowed to continue."
It uses radio waves to pinpoint items, even when they're hidden from view.
"Researchers have been giving robots human-like perception," says MIT Associate Professor Fadel Adib. In a new paper, Adib's team is pushing the technology a step further. "We're trying to give robots superhuman perception," he says.
The researchers have developed a robot that uses radio waves, which can pass through walls, to sense occluded objects. The robot, called RF-Grasp, combines this powerful sensing with more traditional computer vision to locate and grasp items that might otherwise be blocked from view. The advance could one day streamline e-commerce fulfillment in warehouses or help a machine pluck a screwdriver from a jumbled toolkit.
The research will be presented in May at the IEEE International Conference on Robotics and Automation. The paper's lead author is Tara Boroushaki, a research assistant in the Signal Kinetics Group at the MIT Media Lab. Her MIT co-authors include Adib, who is the director of the Signal Kinetics Group; and Alberto Rodriguez, the Class of 1957 Associate Professor in the Department of Mechanical Engineering. Other co-authors include Junshan Leng, a research engineer at Harvard University, and Ian Clester, a PhD student at Georgia Tech.Play video
As e-commerce continues to grow, warehouse work is still usually the domain of humans, not robots, despite sometimes-dangerous working conditions. That's in part because robots struggle to locate and grasp objects in such a crowded environment. "Perception and picking are two roadblocks in the industry today," says Rodriguez. Using optical vision alone, robots can't perceive the presence of an item packed away in a box or hidden behind another object on the shelf — visible light waves, of course, don't pass through walls.
But radio waves can.
For decades, radio frequency (RF) identification has been used to track everything from library books to pets. RF identification systems have two main components: a reader and a tag. The tag is a tiny computer chip that gets attached to — or, in the case of pets, implanted in — the item to be tracked. The reader then emits an RF signal, which gets modulated by the tag and reflected back to the reader.
The reflected signal provides information about the location and identity of the tagged item. The technology has gained popularity in retail supply chains — Japan aims to use RF tracking for nearly all retail purchases in a matter of years. The researchers realized this profusion of RF could be a boon for robots, giving them another mode of perception.
"RF is such a different sensing modality than vision," says Rodriguez. "It would be a mistake not to explore what RF can do."
RF Grasp uses both a camera and an RF reader to find and grab tagged objects, even when they're fully blocked from the camera's view. It consists of a robotic arm attached to a grasping hand. The camera sits on the robot's wrist. The RF reader stands independent of the robot and relays tracking information to the robot's control algorithm. So, the robot is constantly collecting both RF tracking data and a visual picture of its surroundings. Integrating these two data streams into the robot's decision making was one of the biggest challenges the researchers faced.
"The robot has to decide, at each point in time, which of these streams is more important to think about," says Boroushaki. "It's not just eye-hand coordination, it's RF-eye-hand coordination. So, the problem gets very complicated."
The robot initiates the seek-and-pluck process by pinging the target object's RF tag for a sense of its whereabouts. "It starts by using RF to focus the attention of vision," says Adib. "Then you use vision to navigate fine maneuvers." The sequence is akin to hearing a siren from behind, then turning to look and get a clearer picture of the siren's source.
With its two complementary senses, RF Grasp zeroes in on the target object. As it gets closer and even starts manipulating the item, vision, which provides much finer detail than RF, dominates the robot's decision making.
RF Grasp proved its efficiency in a battery of tests. Compared to a similar robot equipped with only a camera, RF Grasp was able to pinpoint and grab its target object with about half as much total movement. Plus, RF Grasp displayed the unique ability to "declutter" its environment — removing packing materials and other obstacles in its way in order to access the target. Rodriguez says this demonstrates RF Grasp's "unfair advantage" over robots without penetrative RF sensing. "It has this guidance that other systems simply don't have."
RF Grasp could one day perform fulfilment in packed e-commerce warehouses. Its RF sensing could even instantly verify an item's identity without the need to manipulate the item, expose its barcode, then scan it. "RF has the potential to improve some of those limitations in industry, especially in perception and localization," says Rodriguez.
Adib also envisions potential home applications for the robot, like locating the right Allen wrench to assemble your Ikea chair. "Or you could imagine the robot finding lost items. It's like a super-Roomba that goes and retrieves my keys, wherever the heck I put them."
The research is sponsored by the National Science Foundation, NTT DATA, Toppan, Toppan Forms, and the Abdul Latif Jameel Water and Food Systems Lab (J-WAFS).
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