livescience--2020-11-02--Were these nails used to crucify Jesus? New evidence revives controversial idea.

Two corroded Roman-era iron nails that some have suggested pinned to the cross appear to have been used in an ancient crucifixion , according to a new study .
This research has reignited debate over the origin of the nails .
The new analysis suggests the nails were lost from the tomb of the Jewish high priest Caiaphas , who reportedly handed Jesus over to the Romans for execution .
Slivers of wood and bone fragments suggest they may have been used in a crucifixion .
Geologist Aryeh Shimron , the lead author of research published in July in the @ @ @ @ @ @ @ and the latest evidence did not prove absolutely that the nails were used to crucify Jesus in Jerusalem in A.D. 33 , but they strengthened the claim .
`` I certainly do not want to say that these nails are from the crucifixion of Jesus of Nazareth , '' Shimron told Live Science .
`` But are they nails from a crucifixion ?
Very likely , yes . ''
Where did the nails originate ?
Israel Hershkovitz , a renowned anthropologist at Tel Aviv University , received the nails in an unmarked box @ @ @ @ @ @ @ an Israeli anthropologist who died in 1986 .
According to the Israel Antiquities Authority ( IAA ) , Haas obtained them from a tomb excavated in the 1970s , decades before the Caiaphas tomb was discovered , .
But the IAA does n't know which tomb the nails came from , and no records of their provenance have ever been found .
In a controversial 2011 documentary called `` The Nails of the Cross , '' however , filmmaker and journalist Simcha Jacobovici suggested the nails were those lost from the Caiaphas tomb @ @ @ @ @ @ @ have been so overcome with guilt about the crucifixion of Jesus that he kept the nails as a memento .
Haaretz reported that some scholars , though no names were given , have called the latest research highly speculative .
But Shimron , a geologist based in Jerusalem who 's retired from the Israel Geological Survey , said the new study gave weight to the documentary 's ideas .
Shimron has not studied the two nails that are the subject of Jacobovici 's 2011 documentary before now , though he was involved in @ @ @ @ @ @ @ Jacobovici 's controversial documentaries on the archaeology of Jesus .
Workers widening a road discovered the first-century `` Caiaphas '' tomb in 1990 in a neighborhood in the southeast of Jerusalem .
The tomb contained 12 ossuaries —– one marked with the name `` Qayafa '' and another , ornately decorated with motifs of flowers , marked with the Aramaic name `` Yehosef Bar Qayafa , '' or `` Joseph son of Caiaphas '' in English .
Most archaeologists now accept that the tomb was used to bury the first-century high priest Caiaphas @ @ @ @ @ @ @ .
Caiaphas , who is is mentioned several times in both the Christian New Testament and a history of the Jews written in the late first century by Flavius Josephus , presided over a sham trial of Jesus for blasphemy , after which Jesus was handed over to the Roman governor for execution , according to the Gospel of Matthew .
The execution was reportedly , when Jesus was nailed to the cross — a common Roman method of capital punishment .
In the latest study , Shimron and his co-authors compared samples @ @ @ @ @ @ @ the ossuaries in the Caiaphas tomb —– stone chests used to hold the bones of people after they had decayed for about a year on a rock shelf .
It found that not only did the physical and chemical signatures of the nails and the ossuaries match , but they also seemed to be unique .
Related : 8 archaeological sites that Jesus may have visited For example , the ratios of isotopes of and — variants of these elements — in both sets of samples suggested they both came from an abnormally @ @ @ @ @ @ @ significant `` flowstone deposits '' —– layers of calcite carbonate formed by flowing water .
These findings match the conditions in the Caiaphas tomb , which is located near an ancient aqueduct and often would have been flooded by its overflow .
The researchers also found evidence on both the nails and the ossuaries of a specific fungus — an unusual type of yeast — that grows only in very damp conditions and has been found in no other tomb in Jerusalem .
`` I think the nails came from that tomb , @ @ @ @ @ @ @ the nails with an electron microscope also found slivers of wood on the nails , which they recognized as cedar , and tiny fragments of bone —– unfortunately now fossilized .
Those discoveries heightened the possibility that the nails came from a crucifixion , but they did not prove it , Shimron said .
The IAA says their records show that two iron nails were also found in the Caiaphas tomb — one inside an unmarked ossuary and another on the ground near the ornate ossuary , possibly where it fell when it @ @ @ @ @ @ @ they were later lost .
The excavator of that tomb suggested they might have been used to scratch inscriptions on the ossuaries , but that idea was never investigated , Shimron said .
The new study indicated the nails from Tel Aviv University were indeed those lost from the Caiaphas tomb , despite the IAA 's denial , he said .
Related : 7 biblical artifacts that will probably never be found According to the theory presented in Jacobovici 's documentary , they might have been buried with Caiaphas because crucifixion nails were @ @ @ @ @ @ @ noted in ancient Jewish writings .
And because Caiaphas is only known for his role in the crucifixion of Jesus , it 's possible that the nails are linked with that event — although it can only be a supposition , Shimron said .
Hershkovitz , who still has possession of the two nails , told Live Science he was not convinced by the latest study , but he did not rule out the possibility that the nails came from the Caiaphas tomb .
The nails are long enough to have been used @ @ @ @ @ @ @ crucifixion , and they are bent upward at the end , — perhaps to prevent the hands being lifted off the cross , he said .
But the presence of bone fragments did not prove the nails were from a crucifixion , because bones from the tomb may have stuck to the nails .
`` Ossuaries are full of human bones , '' he said .
Still , `` there is a possibility — and we have to keep an open mind for every possibility , as scientists , '' Hershkovitz said .

The two Roman-era iron nails are from an unmarked box delivered to Tel Aviv University; new research suggests they could be the two nails lost from the tomb of the Jewish high priest Caiaphas, who presided over the condemnation of Jesus.
Two corroded Roman-era iron nails that some have suggested pinned Jesus to the cross appear to have been used in an ancient crucifixion, according to a new study. This research has reignited debate over the origin of the nails.
The new analysis suggests the nails were lost from the tomb of the Jewish high priest Caiaphas, who reportedly handed Jesus over to the Romans for execution. Slivers of wood and bone fragments suggest they may have been used in a crucifixion.
Geologist Aryeh Shimron, the lead author of research published in July in the journal Archaeological Discovery , said the link to Caiaphas and the latest evidence did not prove absolutely that the nails were used to crucify Jesus in Jerusalem in A.D. 33, but they strengthened the claim.
Related: How Jesus died: Rare evidence of Roman crucifixion found
"I certainly do not want to say that these nails are from the crucifixion of Jesus of Nazareth," Shimron told Live Science. "But are they nails from a crucifixion ? Very likely, yes."
Where did the nails originate?
The ornate ossuary, decorated with motifs of flowers and marked in Aramaic "Joseph son of Caiaphas," was found in a first century tomb in Jerusalem in 1990. Two corroded iron nails were found in the same tomb, but were later lost. (Image credit: Aryeh Shimron)
Israel Hershkovitz, a renowned anthropologist at Tel Aviv University, received the nails in an unmarked box from the collection of Nicu Haas, an Israeli anthropologist who died in 1986.
According to the Israel Antiquities Authority (IAA), Haas obtained them from a tomb excavated in the 1970s, decades before the Caiaphas tomb was discovered, according to Haaretz .
But the IAA doesn't know which tomb the nails came from, and no records of their provenance have ever been found.
In a controversial 2011 documentary called " The Nails of the Cross ," however, filmmaker and journalist Simcha Jacobovici suggested the nails were those lost from the Caiaphas tomb — and that the high priest may have been so overcome with guilt about the crucifixion of Jesus that he kept the nails as a memento.
Related: 8 alleged relics of Jesus of Nazareth
Haaretz reported that some scholars, though no names were given, have called the latest research highly speculative.
But Shimron, a geologist based in Jerusalem who's retired from the Israel Geological Survey, said the new study gave weight to the documentary's ideas. Shimron has not studied the two nails that are the subject of Jacobovici's 2011 documentary before now, though he was involved in a 2015 study tied to another of Jacobovici's controversial documentaries on the archaeology of Jesus.
Experts think the nails are long enough to have nailed up hands in a crucifixion, and may have been bent upwards to prevent the hands being lifted off. (Image credit: Aryeh Shimron)
Workers widening a road discovered the first-century "Caiaphas" tomb in 1990 in a neighborhood in the southeast of Jerusalem. The tomb contained 12 ossuaries —– one marked with the name "Qayafa" and another, ornately decorated with motifs of flowers, marked with the Aramaic name "Yehosef Bar Qayafa," or "Joseph son of Caiaphas" in English. Most archaeologists now accept that the tomb was used to bury the first-century high priest Caiaphas and his family, the study said.
Caiaphas, who is is mentioned several times in both the Christian New Testament and a history of the Jews written in the late first century by Flavius Josephus, presided over a sham trial of Jesus for blasphemy, after which Jesus was handed over to the Roman governor Pontius Pilate for execution, according to the Gospel of Matthew.
The execution was reportedly carried out on Friday April 3, 33 , when Jesus was nailed to the cross — a common Roman method of capital punishment.
The two nails discovered at Tel Aviv University match the chemical signature of the ossuaries in the Caiaphas tomb and have traces of an unusual fungus found there. (Image credit: Aryeh Shimron)
Jerusalem tomb
In the latest study, Shimron and his co-authors compared samples from the two nails with sediments from the ossuaries in the Caiaphas tomb —– stone chests used to hold the bones of people after they had decayed for about a year on a rock shelf.
It found that not only did the physical and chemical signatures of the nails and the ossuaries match, but they also seemed to be unique.
Related: 8 archaeological sites that Jesus may have visited
For example, the ratios of isotopes of carbon and oxygen — variants of these elements — in both sets of samples suggested they both came from an abnormally humid environment, and they both had significant "flowstone deposits" —– layers of calcite carbonate formed by flowing water.
These findings match the conditions in the Caiaphas tomb, which is located near an ancient aqueduct and often would have been flooded by its overflow.
The researchers also found evidence on both the nails and the ossuaries of a specific fungus — an unusual type of yeast — that grows only in very damp conditions and has been found in no other tomb in Jerusalem. "I think the nails came from that tomb," Shimron said.
Their analysis of the nails with an electron microscope also found slivers of wood on the nails, which they recognized as cedar, and tiny fragments of bone —– unfortunately now fossilized. Those discoveries heightened the possibility that the nails came from a crucifixion, but they did not prove it, Shimron said.
Electron microscopy has revealed fragments of bone on the nails, but it's not known how they got there; they may have come from the tomb. (Image credit: Aryeh Shimron)
Mysterious nails
The IAA says their records show that two iron nails were also found in the Caiaphas tomb — one inside an unmarked ossuary and another on the ground near the ornate ossuary, possibly where it fell when it was disturbed by tomb robbers — but they were later lost.
The excavator of that tomb suggested they might have been used to scratch inscriptions on the ossuaries, but that idea was never investigated, Shimron said.
The new study indicated the nails from Tel Aviv University were indeed those lost from the Caiaphas tomb, despite the IAA's denial, he said.
Related: 7 biblical artifacts that will probably never be found
According to the theory presented in Jacobovici's documentary, they might have been buried with Caiaphas because crucifixion nails were thought to be magical — a belief noted in ancient Jewish writings. And because Caiaphas is only known for his role in the crucifixion of Jesus, it's possible that the nails are linked with that event — although it can only be a supposition, Shimron said.
Hershkovitz, who still has possession of the two nails, told Live Science he was not convinced by the latest study, but he did not rule out the possibility that the nails came from the Caiaphas tomb.
The nails are long enough to have been used on a person's hands in a crucifixion, and they are bent upward at the end, — perhaps to prevent the hands being lifted off the cross, he said.
But the presence of bone fragments did not prove the nails were from a crucifixion, because bones from the tomb may have stuck to the nails. "Ossuaries are full of human bones," he said.
Still, "there is a possibility — and we have to keep an open mind for every possibility, as scientists," Hershkovitz said.


livescience--2020-11-02--Why has our normal body temperature been dropping?

Feeling under the weather ?
Chances are you or your doctor will grab a thermometer , take your temperature and hope for the familiar 98.6 degrees Fahrenheit ( 37 degrees Celsius ) everyone recognizes as “ normal.
” But what is normal and why does it matter ?
Despite the fixation on 98.6 F , clinicians recognize that there is no single universal “ normal ” body temperature for everyone at all times .
Throughout the day , your body temperature can vary by as much as 1 F , at its lowest in the early morning and highest in @ @ @ @ @ @ @ you are sick , goes up during and after exercise , varies across the menstrual cycle and varies between individuals .
It also tends to decline with age .
In other words , body temperature is an indicator of what ’ s going on within your body , like a metabolic thermostat .
An intriguing study from earlier this year found that normal body temperature is about 97.5 F in Americans – at least those in Palo Alto , California , where the researchers took hundreds of thousands of temperature readings .
That @ @ @ @ @ @ @ body temperature has been dropping over the past 150 years .
People run cooler today than they did two centuries ago .
The 98.6 F standard for “ normal body temperature ” was first established by the German physician Carl Wunderlich in 1867 after studying 25,000 people in Leipzig .
But anecdotally , lower body temperatures in healthy adults have been widely reported .
And a study in 2017 among 35,000 adults in the U.K. observed a lower average body temperature of 97.9 F. What might cause these subtle but important changes ?
@ @ @ @ @ @ @ in human physiology occurring only in urban , industrialized settings like the U.S. and U.K. ?
One leading hypothesis is that thanks to improved hygiene , sanitation and medical treatment , people today experience fewer of the infections that would trigger higher body temperatures .
In our study , we were able to test that idea directly in a unique setting : among Tsimane horticulturalist-foragers of the Bolivian Amazon .
The Tsimane live in a remote area with little access to modern amenities , and we know from firsthand experience that infections are @ @ @ @ @ @ @ intestinal worms to tuberculosis .
Having worked with the Tsimane studying a variety of topics related to health and aging for two decades , our team had a rich opportunity to observe whether body temperatures were similarly declining in this tropical environment where infections are common .
As part of our ongoing Tsimane Health and Life History Project , a mobile team of Bolivian physicians and researchers has been traveling from village to village monitoring health while treating patients .
They record clinical diagnoses and lab measures of infection at each patient visit @ @ @ @ @ @ @ Bolivia back in 2002 , Tsimane body temperatures were similar to what was found in Germany and the U.S. two centuries ago : averaging at 98.6 F. But over a relatively short period of 16 years , we observed a rapid decline in average body temperature in this population .
The decline is steep : 0.09 F per year .
Today Tsimane body temperatures are roughly 97.7 F. In other words , in less than two decades we ’ re seeing about the same level of decline as that observed in the U.S. @ @ @ @ @ @ @ say this with confidence , as our analysis is based on a large sample ( about 18,000 observations of almost 5,500 adults ) , and we statistically control for multiple other factors that might affect body temperature , like ambient temperature and body mass .
More importantly , while having certain ailments , like respiratory or skin infections , was associated with higher body temperature during a medical visit , adjusting for these infections did not account for the steep decline in body temperature over time .
So why have body temperatures decreased @ @ @ @ @ @ @ Tsimane ?
Fortunately , we had data available from our long-term research in Bolivia to address some possibilities .
For example , declines might be due to the rise of modern health care and lower rates of lingering mild infections now compared to in the past .
But while it may be the case that health has generally improved in Bolivia over the past two decades , infections are still widespread among the Tsimane .
Our results suggest that reduced incidence of infection alone can ’ t explain the observed body temperature declines @ @ @ @ @ @ @ in better condition , and so their bodies don ’ t need to work as hard to fight infection .
Or more access to antibiotics and other treatments means that duration of infection is lower now than in the past .
It ’ s also possible that greater use of certain medications like ibuprofen or aspirin may reduce inflammation and be reflected in the lower temperatures .
However , while lab measures of system-wide inflammation were associated with higher body temperature during patient visits , accounting for this in our analyses did not @ @ @ @ @ @ @ body temperature declined per year .
Another possible explanation for the historical declines in body temperature is that bodies now don ’ t need to work as much to regulate internal body temperature because of air conditioners in the summer and heaters in the winter .
While Tsimane body temperatures do change with the time of year and weather patterns , the Tsimane don ’ t use any advanced technology to regulate their body temperature .
They do , however , have more access to clothes and blankets than they previously did .
@ @ @ @ @ @ @ up for The Conversation ’ s newsletter . ]
Understanding why body temperatures are declining remains an open question for scientists to explore .
Whatever the reason , though , we can confirm that body temperatures are below 98.6 F outside of places like the U.S. and U.K. – even in rural and tropical areas with minimal public health infrastructure , where infections are still the major killers .
We hope that our findings inspire more studies about how improved conditions might lower body temperature .
As it ’ s fast and easy @ @ @ @ @ @ @ day prove to be a simple but useful indicator , like life expectancy , that provides new insight into population health .
This article is republished from The Conversation under a Creative Commons license .
Read the original article .
Follow all of the Expert Voices issues and debates — and become part of the discussion — on Facebook and Twitter .
The views expressed are those of the author and do not necessarily reflect the views of the publisher .
This version of the article was originally published on Live Science .

Feeling under the weather? Chances are you or your doctor will grab a thermometer, take your temperature and hope for the familiar 98.6 degrees Fahrenheit (37 degrees Celsius) everyone recognizes as “normal.”
But what is normal and why does it matter? Despite the fixation on 98.6 F, clinicians recognize that there is no single universal “normal” body temperature for everyone at all times. Throughout the day, your body temperature can vary by as much as 1 F, at its lowest in the early morning and highest in the late afternoon. It changes when you are sick, goes up during and after exercise, varies across the menstrual cycle and varies between individuals. It also tends to decline with age.
In other words, body temperature is an indicator of what’s going on within your body, like a metabolic thermostat.
An intriguing study from earlier this year found that normal body temperature is about 97.5 F in Americans – at least those in Palo Alto, California, where the researchers took hundreds of thousands of temperature readings. That meant that in the U.S., normal body temperature has been dropping over the past 150 years. People run cooler today than they did two centuries ago.
The 98.6 F standard for “normal body temperature” was first established by the German physician Carl Wunderlich in 1867 after studying 25,000 people in Leipzig. But anecdotally, lower body temperatures in healthy adults have been widely reported. And a study in 2017 among 35,000 adults in the U.K. observed a lower average body temperature of 97.9 F.
What might cause these subtle but important changes? And are these provocative hints of changes in human physiology occurring only in urban, industrialized settings like the U.S. and U.K.?
One leading hypothesis is that thanks to improved hygiene, sanitation and medical treatment, people today experience fewer of the infections that would trigger higher body temperatures. In our study, we were able to test that idea directly in a unique setting: among Tsimane horticulturalist-foragers of the Bolivian Amazon.
Tracking temperature in the Tsimane
The Tsimane live in a remote area with little access to modern amenities, and we know from firsthand experience that infections are common – from the common cold to intestinal worms to tuberculosis. Having worked with the Tsimane studying a variety of topics related to health and aging for two decades, our team had a rich opportunity to observe whether body temperatures were similarly declining in this tropical environment where infections are common.
As part of our ongoing Tsimane Health and Life History Project, a mobile team of Bolivian physicians and researchers has been traveling from village to village monitoring health while treating patients. They record clinical diagnoses and lab measures of infection at each patient visit.
When we first started working in Bolivia back in 2002, Tsimane body temperatures were similar to what was found in Germany and the U.S. two centuries ago: averaging at 98.6 F. But over a relatively short period of 16 years, we observed a rapid decline in average body temperature in this population. The decline is steep: 0.09 F per year. Today Tsimane body temperatures are roughly 97.7 F.
In other words, in less than two decades we’re seeing about the same level of decline as that observed in the U.S. over approximately two centuries. We can say this with confidence, as our analysis is based on a large sample (about 18,000 observations of almost 5,500 adults), and we statistically control for multiple other factors that might affect body temperature, like ambient temperature and body mass.
More importantly, while having certain ailments, like respiratory or skin infections, was associated with higher body temperature during a medical visit, adjusting for these infections did not account for the steep decline in body temperature over time.
A clear drop, unclear why
So why have body temperatures decreased over time, both for Americans and Tsimane? Fortunately, we had data available from our long-term research in Bolivia to address some possibilities.
For example, declines might be due to the rise of modern health care and lower rates of lingering mild infections now compared to in the past. But while it may be the case that health has generally improved in Bolivia over the past two decades, infections are still widespread among the Tsimane. Our results suggest that reduced incidence of infection alone can’t explain the observed body temperature declines.
It could be that people are in better condition, and so their bodies don’t need to work as hard to fight infection. Or more access to antibiotics and other treatments means that duration of infection is lower now than in the past. It’s also possible that greater use of certain medications like ibuprofen or aspirin may reduce inflammation and be reflected in the lower temperatures. However, while lab measures of system-wide inflammation were associated with higher body temperature during patient visits, accounting for this in our analyses did not affect our estimate of the amount that body temperature declined per year.
Another possible explanation for the historical declines in body temperature is that bodies now don’t need to work as much to regulate internal body temperature because of air conditioners in the summer and heaters in the winter. While Tsimane body temperatures do change with the time of year and weather patterns, the Tsimane don’t use any advanced technology to regulate their body temperature. They do, however, have more access to clothes and blankets than they previously did.
[Deep knowledge, daily. Sign up for The Conversation’s newsletter.]
Understanding why body temperatures are declining remains an open question for scientists to explore. Whatever the reason, though, we can confirm that body temperatures are below 98.6 F outside of places like the U.S. and U.K. – even in rural and tropical areas with minimal public health infrastructure, where infections are still the major killers.
We hope that our findings inspire more studies about how improved conditions might lower body temperature. As it’s fast and easy to measure, body temperature might one day prove to be a simple but useful indicator, like life expectancy, that provides new insight into population health.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Follow all of the Expert Voices issues and debates — and become part of the discussion — on Facebook and Twitter. The views expressed are those of the author and do not necessarily reflect the views of the publisher.
This version of the article was originally published on Live Science.


livescience--2020-11-02--COVID-19 infects the mouth. Could that explain patients' taste loss?

The coronavirus SARS-CoV-2 can infect cells in the mouth , which may spur the virus 's spread both in the body and to other people , according to a preliminary study .
In the new study , posted Oct. 27 to the preprint database , researchers predicted which mouth tissues might be most vulnerable to SARS-CoV-2 , the virus that causes COVID-19 .
So the team examined — a kind of genetic material that tells the cells ' protein-making factories what to build — for different cell types in the mouth .
They found that , compared with other oral @ @ @ @ @ @ @ , and tonsils carry the most RNA linked to proteins that the needs to infect cells .
Namely , these include the ACE2 receptor , which the virus plugs into , and an enzyme called TMPRSS , which allows the virus to fuse its membrane with that of the host cell and slip inside .
The researchers went on to sample saliva from COVID-19 patients and found that , since mouth cells slough off into our spit , they could detect infected cells floating in the samples .
The more virus they found @ @ @ @ @ @ @ had as one of their , although saliva from several asymptomatic people also contained infected cells .
In addition , the team examined mouth tissue from COVID-19 patients who had died , and they found more evidence of infection in the vulnerable cell types they had flagged .
`` Our study shows that the mouth is a route of infection as well as an incubator for the SARS-CoV-2 that causes COVID-19 , '' Dr. Kevin Byrd , a research scholar and manager of Oral and Craniofacial Research at the American Dental Association Science @ @ @ @ @ @ @ in an email .
Theoretically , SARS-CoV-2 infection in the mouth could cause changes in saliva production or quality , contributing to symptoms of taste loss , he said .
Future research could reveal how this mouth infection affects the course of illness in COVID-19 patients , as well as how those infected cells contribute to the spread of the coronavirus between people .
Related : 20 of the worst epidemics and pandemics in history '' Seeing the presence of the virus within the salivary glands , I think that 's the novelty @ @ @ @ @ @ @ an assistant professor and chief of the Sol Silverman Oral Medicine Clinic at the University of California , San Francisco , who was not involved in the study .
`` That 's what 's interesting to me as a clinician . ''
That said , the study only looked at a few dozen people , Villa said .
`` The numbers are small , for sure , so it will be interesting to see what happens if you look at more patients and more tissues , '' he said .
Thankfully , the @ @ @ @ @ @ @ could make future studies of oral infection easier .
Specifically , they created an atlas of different cells in the mouth , which essentially serves as a map of which cells contain what RNA , and where .
Byrd and his co-author Dr. Blake Warner , an assistant clinical investigator in the Salivary Disorders Unit at the National Institute of Dental and Craniofacial Research , a branch of the U.S. National Institutes of Health , worked with an organization called the to organize and refine the data .
`` This new atlas provided @ @ @ @ @ @ @ cell types … at once for the common 'front doors ' the virus uses to enter cells for infection , '' Byrd said .
The atlas helped them pinpoint the cells at highest risk for SARS-CoV-2 infection , and then the team checked their work against saliva samples and autopsied tissue from patients .
While the study makes a convincing case that SARS-CoV-2 infects cells in the mouth , some questions remain unanswered .
Related : Going viral : 6 new findings about viruses For one , the study can not show how @ @ @ @ @ @ @ actually comes from infected mouth cells .
It 's possible that some virus originates from elsewhere , such as the nose or the lungs , Byrd said .
`` However , we found these underappreciated but widely distributed salivary glands '' — the so-called minor salivary glands — `` can make their own virus after infection , '' he said .
The team confirmed this by checking the levels of coronavirus RNA in the cells using PCR , a kind of test often used to detect and diagnose COVID-19 , as well as @ @ @ @ @ @ @ also detects genetic material .
`` We hypothesize this is the primary source of virus in saliva , '' Byrd told Live Science .
This would need to be confirmed in more COVID-19 patients .
In addition , we do n't yet know how the function of salivary glands changes after getting infected with the coronavirus .
`` If the saliva production is somehow compromised , one could speculate that one could develop taste changes or loss of taste , '' because saliva carries molecules to taste receptors on the tongue , Villa @ @ @ @ @ @ @ a hypothesis , '' Villa said .
Oral SARS-CoV-2 infection may also contribute to other symptoms , such as dry mouth and blistering in mucosal tissues , the study authors wrote .
A better understanding of how the coronavirus infects mouth cells , at the molecular level , could help improve treatments for patients with these symptoms , Byrd said .
Several clinical trials are also investigating whether oral rinses could help prevent or treat COVID-19 infection ; UCSF researchers plan to conduct one such trial , according to , and Villa is @ @ @ @ @ @ @ additional trial of several rinses , he told Live Science .
In the meantime , the new study drives home one important point : Asymptomatic people can carry plenty of viral particles in their saliva .
In two asymptomatic people included in the study , the virus was found in their saliva 14 days after their first positive test , even though they had already tested negative for the virus in their nose and throat at that point .
The study did not address whether the detected virus was still viable , meaning @ @ @ @ @ @ @ research mightily underscores the importance of the public health measures we know are effective — masks , social distancing and handwashing — whether you have symptoms or not , '' Byrd said .
In terms of how oral infection fits into the big picture of COVID-19 , `` there is much to learn about where SARS-CoV-2 begins , travels within our bodies and finally is cleared , '' he said .

The coronavirus SARS-CoV-2 can infect cells in the mouth, which may spur the virus's spread both in the body and to other people, according to a preliminary study.
In the new study, posted Oct. 27 to the preprint database medRxiv , researchers predicted which mouth tissues might be most vulnerable to SARS-CoV-2, the virus that causes COVID-19. So the team examined RNA — a kind of genetic material that tells the cells' protein-making factories what to build — for different cell types in the mouth. They found that, compared with other oral tissues, cells of the salivary glands, tongue and tonsils carry the most RNA linked to proteins that the coronavirus needs to infect cells. Namely, these include the ACE2 receptor, which the virus plugs into, and an enzyme called TMPRSS, which allows the virus to fuse its membrane with that of the host cell and slip inside.
The researchers went on to sample saliva from COVID-19 patients and found that, since mouth cells slough off into our spit, they could detect infected cells floating in the samples. The more virus they found, the more likely a given patient had smell and taste loss as one of their symptoms , although saliva from several asymptomatic people also contained infected cells. In addition, the team examined mouth tissue from COVID-19 patients who had died, and they found more evidence of infection in the vulnerable cell types they had flagged.
"Our study shows that the mouth is a route of infection as well as an incubator for the SARS-CoV-2 virus that causes COVID-19," Dr. Kevin Byrd, a research scholar and manager of Oral and Craniofacial Research at the American Dental Association Science and Research Institute, told Live Science in an email.
Theoretically, SARS-CoV-2 infection in the mouth could cause changes in saliva production or quality, contributing to symptoms of taste loss, he said. Future research could reveal how this mouth infection affects the course of illness in COVID-19 patients, as well as how those infected cells contribute to the spread of the coronavirus between people.
Related: 20 of the worst epidemics and pandemics in history
"Seeing the presence of the virus within the salivary glands, I think that's the novelty," said Dr. Alessandro Villa, an assistant professor and chief of the Sol Silverman Oral Medicine Clinic at the University of California, San Francisco, who was not involved in the study. "That's what's interesting to me as a clinician."
That said, the study only looked at a few dozen people, Villa said. "The numbers are small, for sure, so it will be interesting to see what happens if you look at more patients and more tissues," he said.
Thankfully, the study authors helped craft a tool that could make future studies of oral infection easier. Specifically, they created an atlas of different cells in the mouth, which essentially serves as a map of which cells contain what RNA, and where. Byrd and his co-author Dr. Blake Warner, an assistant clinical investigator in the Salivary Disorders Unit at the National Institute of Dental and Craniofacial Research, a branch of the U.S. National Institutes of Health, worked with an organization called the Human Cell Atlas to organize and refine the data.
"This new atlas provided us a way to analyze 50 oral cell types … at once for the common 'front doors' the virus uses to enter cells for infection," Byrd said. The atlas helped them pinpoint the cells at highest risk for SARS-CoV-2 infection, and then the team checked their work against saliva samples and autopsied tissue from patients.
While the study makes a convincing case that SARS-CoV-2 infects cells in the mouth, some questions remain unanswered.
Related: Going viral: 6 new findings about viruses
For one, the study cannot show how much of the virus found in saliva actually comes from infected mouth cells. It's possible that some virus originates from elsewhere, such as the nose or the lungs, Byrd said. "However, we found these underappreciated but widely distributed salivary glands" — the so-called minor salivary glands — "can make their own virus after infection," he said. The team confirmed this by checking the levels of coronavirus RNA in the cells using PCR, a kind of test often used to detect and diagnose COVID-19, as well as a technique called in situ hybridization that also detects genetic material.
"We hypothesize this is the primary source of virus in saliva," Byrd told Live Science. This would need to be confirmed in more COVID-19 patients.
In addition, we don't yet know how the function of salivary glands changes after getting infected with the coronavirus. "If the saliva production is somehow compromised, one could speculate that one could develop taste changes or loss of taste," because saliva carries molecules to taste receptors on the tongue, Villa said. "Again, it's a hypothesis," Villa said. Oral SARS-CoV-2 infection may also contribute to other symptoms , such as dry mouth and blistering in mucosal tissues, the study authors wrote.
A better understanding of how the coronavirus infects mouth cells, at the molecular level, could help improve treatments for patients with these symptoms, Byrd said. Several clinical trials are also investigating whether oral rinses could help prevent or treat COVID-19 infection; UCSF researchers plan to conduct one such trial, according to ClinicalTrials.gov , and Villa is working with another team to organize an additional trial of several rinses, he told Live Science.
In the meantime, the new study drives home one important point: Asymptomatic people can carry plenty of viral particles in their saliva. In two asymptomatic people included in the study, the virus was found in their saliva 14 days after their first positive test, even though they had already tested negative for the virus in their nose and throat at that point. The study did not address whether the detected virus was still viable, meaning it could infect cells.
"This research mightily underscores the importance of the public health measures we know are effective — masks, social distancing and handwashing — whether you have symptoms or not," Byrd said. In terms of how oral infection fits into the big picture of COVID-19, "there is much to learn about where SARS-CoV-2 begins, travels within our bodies and finally is cleared," he said.
Originally published on Live Science.


livescience--2020-11-02--Platypuses glow an eerie blue-green under UV light

Duck-billed , egg-laying just got a little weirder : It turns out their fur glows green and blue under ( UV ) light .
Under visible light a platypus ’ s extremely dense fur — which insulates and protects them in cold water — is a drab brown , so the trippy glow revealed under UV light on a stuffed museum specimen was a big surprise .
Biofluorescence — absorbing and re-emitting light as a different color — is widespread in fish , amphibians , birds and reptiles .
But the trait is much rarer in mammals , and this @ @ @ @ @ @ @ egg-laying mammals , also known as monotremes , scientists reported in a new study .
Prior to this discovery , biofluorescence was known in only two mammals : flying squirrels , which are placental mammals , and opossums , which are marsupials , according to the study , published online Oct. 15 in the journal .
Study co-author Allison Kohler , a doctoral candidate in the Texas A & M University Wildlife and Fisheries Department in College Station , Texas , had previously tested museum specimens of flying and found that all three @ @ @ @ @ @ @ squirrel ( Glaucomys sabrinus ) , the southern flying squirrel ( Glaucomys volans ) and the Humboldt ’ s flying squirrel ( Glaucomys oregonensis ) — glowed bright pink in UV light .
Kohler and her colleagues reported their results on Jan. 23 , 2019 , in the .
While testing the flying squirrel museum specimens for signs of biofluorescence , they decided to look at other mammal species in the same collections too , .
Platypuses are semiaquatic and live in eastern Australia , and they are such a peculiar hodgepodge of @ @ @ @ @ @ @ from unrelated animals ; so perhaps fittingly , their scientific name , Ornithorhynchus anatinus , means bird-snouted flat-foot , according to London 's ( NHM ) .
These oddball mammals have furry bodies ; flat and hairless beaver-like tails ; webbed feet ( males also have spurs on their hind legs that are loaded with venom ) ; and broad bills like a duck 's .
When 19th-century Europeans first saw preserved skins of these strange-looking creatures , many experts thought the animal was a taxidermy hoax , with a duck 's beak @ @ @ @ @ @ @ according to NHM .
The discovery of platypuses ' fluorescent glow came from two specimens from Tasmania , Australia , in the collection of The Field Museum in Chicago .
Both specimens — one male and one female — displayed the glow , according to the study .
The scientists then tested a third specimen at the University of Nebraska State Museum in Lincoln , Nebraska ; that platypus , a male , had been collected in New South Wales , Australia .
It also glowed green in UV light .
The greenish-bluish @ @ @ @ @ @ @ in the male and female platypuses , suggesting it is n't a sexual trait tied to reproduction , the researchers reported .
Platypuses navigate their twilit , aquatic environments through mechanoreception , the detection of mechanical stimuli such as touch and sound , and electrostimulation , the perception of natural electrical signals .
Because they do n't rely heavily on sight , it 's possible that their biofluorescence is not used to communicate with each other , but to reduce their visibility to predators , as in the case in some biofluorescent crustaceans @ @ @ @ @ @ @ be essential to document platypus biofluorescence and its ecological function in wild animals , '' the study authors wrote .
Discovering the platypus 's secret glow also sheds light on this trait in mammals , revealing that it 's not just a few highly specialized species that glow in the dark .
`` Instead , it appears across the phylogeny , '' the scientists said .
These biofluorescent mammals occupy diverse ecosystems spanning three continents .
And now , with the addition of the platypus , they represent all of the major mammalian @ @ @ @ @ @ @ monotremes .
One possible explanation is that mammal biofluorescence , rare though it is , may be an ancestral trait that emerged early in the group 's family tree , according to the study .

Duck-billed, egg-laying platypuses just got a little weirder: It turns out their fur glows green and blue under ultraviolet (UV) light.
Under visible light a platypus’s extremely dense fur — which insulates and protects them in cold water — is a drab brown, so the trippy glow revealed under UV light on a stuffed museum specimen was a big surprise.
Biofluorescence — absorbing and re-emitting light as a different color — is widespread in fish, amphibians, birds and reptiles. But the trait is much rarer in mammals, and this is the first evidence of biofluorescence in egg-laying mammals, also known as monotremes, scientists reported in a new study.
Related: Extreme life on Earth: 8 bizarre creatures
Prior to this discovery, biofluorescence was known in only two mammals: flying squirrels, which are placental mammals, and opossums, which are marsupials, according to the study, published online Oct. 15 in the journal Mammalia .
Study co-author Allison Kohler, a doctoral candidate in the Texas A&M University Wildlife and Fisheries Department in College Station, Texas, had previously tested museum specimens of flying squirrels and found that all three North American species — the northern flying squirrel (Glaucomys sabrinus), the southern flying squirrel (Glaucomys volans) and the Humboldt’s flying squirrel (Glaucomys oregonensis) — glowed bright pink in UV light. Kohler, then an undergraduate at Northland College in Ashland, Wisconsin, and her colleagues reported their results on Jan. 23, 2019, in the Journal of Mammalogy .
While testing the flying squirrel museum specimens for signs of biofluorescence, they decided to look at other mammal species in the same collections too, according to a statement .
"We were preparing for our second day at the Field Museum in Chicago to document biofluorescence in New World flying squirrels, and I started wondering how broadly distributed this trait might be within the animal kingdom," said Erik Olson, co-author of the new study and an associate professor of natural resources at Northland College. The researchers knew that platypuses — like flying squirrels — were active at night and during twilight, when an eerie glow would be visible. This made platypuses promising candidates for finding biofluorescence in monotremes, Olson told Live Science in an email.
"Plus, who doesn’t want to examine a platypus specimen?" he added. "We all agreed that we should explore this idea."
Platypuses are semiaquatic and live in eastern Australia, and they are such a peculiar hodgepodge of body parts that they seem cobbled together from unrelated animals; so perhaps fittingly, their scientific name, Ornithorhynchus anatinus, means bird-snouted flat-foot, according to London's Natural History Museum (NHM).
These oddball mammals have furry bodies; flat and hairless beaver-like tails; webbed feet (males also have spurs on their hind legs that are loaded with venom); and broad bills like a duck's. When 19th-century Europeans first saw preserved skins of these strange-looking creatures, many experts thought the animal was a taxidermy hoax, with a duck's beak sewn to a mole's body, according to NHM.
The discovery of platypuses' fluorescent glow came from two specimens from Tasmania, Australia, in the collection of The Field Museum in Chicago. Both specimens — one male and one female — displayed the glow, according to the study. The scientists then tested a third specimen at the University of Nebraska State Museum in Lincoln, Nebraska; that platypus, a male, had been collected in New South Wales, Australia. It also glowed green in UV light.
A male platypus (Ornithorhynchus anatinus) museum specimen (FMNH 16612) collected from Tasmania, Australia, photographed under visible light and ultraviolet (UV) light without and with a yellow camera lens filter. (Image credit: Mammalia 2020; 10.1515/mammalia-2020-0027)
The greenish-bluish color displayed a similar pattern and intensity in the male and female platypuses, suggesting it isn't a sexual trait tied to reproduction, the researchers reported.
Platypuses navigate their twilit, aquatic environments through mechanoreception, the detection of mechanical stimuli such as touch and sound, and electrostimulation, the perception of natural electrical signals. Because they don't rely heavily on sight, it's possible that their biofluorescence is not used to communicate with each other, but to reduce their visibility to predators, as in the case in some biofluorescent crustaceans.
"If there is an ecological function, it likely has to do with interactions between platypuses and other species," such as predators, Olson said in the email. "However, there is a possibility that the trait has little or no ecological function. Only further research can tell," Olson said.
Discovering the platypus's secret glow also sheds light on this trait in mammals, revealing that it's not just a few highly specialized species that glow in the dark.
"Instead, it appears across the phylogeny," the scientists reported.
These biofluorescent mammals occupy diverse ecosystems spanning three continents. And now, with the addition of the platypus, they represent all of the major mammalian lineages; placental mammals, marsupials and monotremes. One possible explanation is that mammal biofluorescence, rare though it is, may be an ancestral trait that emerged early in the group's family tree, according to the study.
"Our discovery of this trait reminds us that the natural world is still full of mysteries," Olson said. "Hopefully, our work shines a light on this unique and near threatened species."
Originally published on Live Science.


livescience--2020-11-03--Mass grave of Tulsa race massacre victims possibly unearthed in Oklahoma cemetery

More than 20 years after she started to unearth the truth about the 1921 race massacre in Tulsa , Oklahoma , Phoebe Stubblefield heard a shout outside the trench in the city 's Oaklawn Cemetery where she was digging .
It came from her colleagues working nearby , who had just uncovered the first two of what would turn out to be roughly a dozen coffins in an unmarked mass grave , which may hold the remains of Black victims of the massacre , estimated to have killed up to 300 mostly Black people .
`` My dominant emotion and @ @ @ @ @ @ @ Stubblefield told Live Science .
`` To finally find them … I was n't surprised , but I was pleased , in the way that your suspicions bear out with testing . ''
Stubblefield , a forensic anthropologist at the University of Florida who often investigates human remains found by law enforcement agencies , was a member of the original commission created by the Oklahoma state legislature in 1997 to investigate the 1921 Tulsa massacre.The commission produced a that recommended , among other things , that the state should pay reparations to the @ @ @ @ @ @ @ the massacre ; but many of its recommendations were ignored in the enacted by the Oklahoma Legislature .
Although that statute acknowledged the state 's `` moral responsibility '' for the race riot and affirmed that no race had the right to subordinate any other , it did not enact reparations .
Now , the significance of the 1921 massacre has been heightened by a investigating the events of the massacre ahead of its centenary next year .
Almost a year ago , archaeologists found signs that some victims may have been buried @ @ @ @ @ @ @ `` Sexton '' area of Oaklawn Cemetery ; but excavations in July found no graves there , .
Last week , however , excavation crews unearthed , and possibly more , in a nearby part of the cemetery known as `` Potters ' Field . ''
It 's not yet known whether the coffins hold the remains of Black victims of the 1921 massacre , but there are compelling reasons to believe that they do , said Kary Stackelbeck , the Oklahoma state archaeologist who is leading the current excavations .
`` The @ @ @ @ @ @ @ section of the Potter 's Field , which was established during the Jim Crow era , '' Stackelbeck told Live Science in an email .
Jim Crow was the system of racial caste segregation in place in parts of the U.S. between 1877 and the mid-1960s , .
That location corresponds with witness accounts and documentary evidence , including a 1921 newspaper report that the city would bury `` the bodies of 18 Negroes , killed in the rioting '' at that site , she said .
`` I felt a sense of @ @ @ @ @ @ @ .
`` We were anticipating finding individual grave shafts of perhaps 18 [ people ] , and we ended up finding a mass grave that could contain many more than that number . ''
The archaeologists expect the remains will be in `` reasonable , but not excellent '' condition after almost 100 years in the ground , she said .
`` We expect they can be exhumed , but we will have to practice careful excavation and take special measures to ensure that they remain sufficiently intact to allow for specialized analysis @ @ @ @ @ @ @ through a legal process to exhume the remains , which could take several months .
They 'll be followed by a series of forensic tests , led by Stubblefield , to try to determine their likely sex , age at death , height and ancestry .
Stubblefield said the ancestry of a person — such as if they are of African or European descent — can typically be established by examining the facial structure of the skull .
Such examinations can look at the shapes of the eye sockets , the nasal aperture @ @ @ @ @ @ @ .
The prosperous Tulsa neighborhood of Greenwood was one of the most prosperous African-American communities in the U.S. in the earlier 20th century , when it was popularly known as the `` Black Wall Street . ''
Its thriving businesses included shops , banks , theaters , grocery stores , hotels , restaurants , newspaper publishers and libraries ; several members of Greenwood 's Black community were wealthy entrepreneurs .
But the prosperity of Greenwood and the , during which white supremacists violently attacked Black people in several U.S. cities after the end @ @ @ @ @ @ @ with the majority white population of the city .
On May 31 , 1921 , the arrest of a young Black man for allegedly assaulting a young white woman sparked widespread rioting , followed by deadly shootings between rival racial groups .
By the next day , a white mob had massacred hundreds of Black people and deliberately burned down the Greenwood neighborhood .
Some witnesses said even private planes were used in the attacks .
The Tulsa race massacre was n't officially recognized by the state until 2001 , and accounts of @ @ @ @ @ @ @ recent decades , Oklahoma and the city of Tulsa have tried to better come to terms with this brutal part of their history .
It 's thought that most people who were alive at the time have now passed away ; one of the last known survivors , the psychologist and professor Olivia Juliette Hooker , died in 2018 at the age of 103 .

Archaeologists and observers watch during a test excavation of the 1921 Tulsa Race Massacre Graves at Oaklawn Cemetery in Tulsa, Oklahoma, on July 13, 2020.
More than 20 years after she started to unearth the truth about the 1921 race massacre in Tulsa, Oklahoma, Phoebe Stubblefield heard a shout outside the trench in the city's Oaklawn Cemetery where she was digging.
It came from her colleagues working nearby, who had just uncovered the first two of what would turn out to be roughly a dozen coffins in an unmarked mass grave, which may hold the remains of Black victims of the massacre, estimated to have killed up to 300 mostly Black people.
"My dominant emotion and all of this is gratitude," Stubblefield told Live Science. "To finally find them … I wasn't surprised, but I was pleased, in the way that your suspicions bear out with testing."
Related: Photos: Evidence of a legendary massacre in Alaska
Stubblefield, a forensic anthropologist at the University of Florida who often investigates human remains found by law enforcement agencies, was a member of the original commission created by the Oklahoma state legislature in 1997 to investigate the 1921 Tulsa massacre.The commission produced a final report in 2001 that recommended, among other things, that the state should pay reparations to the descendants of Black victims and survivors of the massacre; but many of its recommendations were ignored in the eventual statute enacted by the Oklahoma Legislature. Although that statute acknowledged the state's "moral responsibility" for the race riot and affirmed that no race had the right to subordinate any other, it did not enact reparations.
Now, the significance of the 1921 massacre has been heightened by a second commission investigating the events of the massacre ahead of its centenary next year.
Almost a year ago, archaeologists found signs that some victims may have been buried in an unmarked mass grave in the "Sexton" area of Oaklawn Cemetery; but excavations in July found no graves there, Live Science previously reported .
Last week, however, excavation crews unearthed at least 12 unmarked coffins , and possibly more, in a nearby part of the cemetery known as "Potters' Field."
Unknown remains
It's not yet known whether the coffins hold the remains of Black victims of the 1921 massacre, but there are compelling reasons to believe that they do, said Kary Stackelbeck, the Oklahoma state archaeologist who is leading the current excavations.
"The mass grave is located in the African-American section of the Potter's Field, which was established during the Jim Crow era," Stackelbeck told Live Science in an email. Jim Crow was the system of racial caste segregation in place in parts of the U.S. between 1877 and the mid-1960s, according to Ferris State University .
That location corresponds with witness accounts and documentary evidence, including a 1921 newspaper report that the city would bury "the bodies of 18 Negroes, killed in the rioting" at that site, she said.
Related: 25 grisly archaeological discoveries
"I felt a sense of relief and excitement," Stackelbeck said. "We were anticipating finding individual grave shafts of perhaps 18 [people], and we ended up finding a mass grave that could contain many more than that number."
The archaeologists expect the remains will be in "reasonable, but not excellent" condition after almost 100 years in the ground, she said. "We expect they can be exhumed, but we will have to practice careful excavation and take special measures to ensure that they remain sufficiently intact to allow for specialized analysis."
The commission will now go through a legal process to exhume the remains, which could take several months. They'll be followed by a series of forensic tests, led by Stubblefield, to try to determine their likely sex, age at death, height and ancestry.
Stubblefield said the ancestry of a person — such as if they are of African or European descent — can typically be established by examining the facial structure of the skull. Such examinations can look at the shapes of the eye sockets, the nasal aperture, and the bones of the jaw.
Tulsa race massacre
The Tulsa neighborhood of Greenwood, also called "Black Wall Street," was burned during the Tulsa race riots in June 1921. (Image credit: Universal HIstory Archive/Universal Images Group via Getty Images)
The prosperous Tulsa neighborhood of Greenwood was one of the most prosperous African-American communities in the U.S. in the earlier 20th century, when it was popularly known as the "Black Wall Street."
Its thriving businesses included shops, banks, theaters, grocery stores, hotels, restaurants, newspaper publishers and libraries; several members of Greenwood's Black community were wealthy entrepreneurs.
But the prosperity of Greenwood and the "Red Summer" of 1919 , during which white supremacists violently attacked Black people in several U.S. cities after the end of World War I , may have led to conflicts with the majority white population of the city.
Related: Psychology of hate: What motivates white supremacists?
On May 31, 1921, the arrest of a young Black man for allegedly assaulting a young white woman sparked widespread rioting, followed by deadly shootings between rival racial groups. By the next day, a white mob had massacred hundreds of Black people and deliberately burned down the Greenwood neighborhood. Some witnesses said even private planes were used in the attacks.
The Tulsa race massacre wasn't officially recognized by the state until 2001, and historians have claimed accounts of the violence were suppressed.
But in recent decades, Oklahoma and the city of Tulsa have tried to better come to terms with this brutal part of their history. It's thought that most people who were alive at the time have now passed away; one of the last known survivors, the psychologist and professor Olivia Juliette Hooker, died in 2018 at the age of 103 .
Originally published on Live Science.


livescience--2020-11-03--The International Space Station can't last forever. Here's how it will eventually die by fire.

What goes up must come down — including , sadly enough , the .
For precisely 20 years now , the massive orbiting laboratory has constantly been home to humans , the lucky handful of Earthlings who at any given time venture into the topsy-turvy world of .
But like the rest of us , the International Space Station is aging .
And it ca n't stay in orbit on its own indefinitely — it needs a regular boost or fuel injection from visiting spacecraft .
If those boosts stop or something else goes wrong , sooner or later , @ @ @ @ @ @ @ , any that comes to the space station , or indeed any ferry ship , usually has surplus propellant to a certain degree , '' Jonathan McDowell , an astronomer at Harvard who specializes in tracking objects in and falling out of orbit , told Space.com .
`` They have to have propellant to do the rendezvous , and then they can sometimes have extra to do a reboost . ''
For now , those flights through at least 2024 .
And because of the station 's international nature — it 's a @ @ @ @ @ @ @ , Canada , Japan and the participating nations of the European Space Agency — the decision to retire it will always be based on both engineering and politics .
`` While ISS is currently approved to operate through at least December 2024 by the international partner governments , from a technical standpoint , we have cleared ISS to fly until the , '' NASA officials wrote in a statement to Space.com .
`` Additionally , our analysis has not identified any issues that would preclude us from extending beyond 2028 if needed .
@ @ @ @ @ @ @ 's time will come .
The facility is aging and at constant risk of impacts from space debris and micrometeorites .
If humans do n't retire it , eventually the hazards of space will .
The eventual fate of the space station has always been a specter for NASA and , Russia 's federal space agency , but as time has passed , it has loomed larger on the minds of space experts .
`` 'Oh , we 'll bring it down eventually , ' the idea has always been ; 'We commit @ @ @ @ @ @ @ sense is that they did n't actually think through the details until about five years ago , '' McDowell said .
`` Until then it was like , 'La la la , it 's in orbit , we 're still building it , we 're not going to worry about how to get rid of it . '
Which maybe is n't quite the way you should do things . ''
One major voice in changing that has been NASA 's Aerospace Safety Advisory Panel , a group that evaluates the safety measures @ @ @ @ @ @ @ panel has been raising concerns for at least a decade about how the space station will end , spurred by the then-upcoming retirement of NASA 's space shuttle vehicles , which could have been used to deorbit the International Space Station .
The group is still citing the issue regularly in its analyses of NASA policies .
`` The panel continues to track the open work status on the planned deorbit strategy for ISS and the fine-tuning of some wording in the related space station program document , '' David West , a @ @ @ @ @ @ @ the group 's quarterly meeting , which was held virtually on Oct. 1 .
`` We will continue to monitor the progress of getting agreement on the strategy by all parties . ''
Scenarios for both a scheduled and a response if something goes very wrong are in the works , NASA confirmed , but are not yet public .
`` NASA is actively working with the entire International Space Station partnership on plans to safely deorbit the space station at the end of its lifetime , '' NASA officials wrote in a @ @ @ @ @ @ @ station began in the 1980s , and while today the concept of a massive orbiting laboratory is unremarkable , at the time it was unprecedented .
`` No one had any idea how to build something like this when we started out on the ISS , '' Christian Maender , director of in-space manufacturing and research for Houston-based company Axiom , which is planning on building its own space station by jumping off the International Space Station , told Space.com .
`` We built the largest peacetime engineering project ever , and by @ @ @ @ @ @ @ never actually saw each other or touched each other until they got to orbit . ''
All told , space station construction required 42 separate launches .
The facility would weigh over 900,000 lbs .
( 420,000 kilograms ) on Earth , is nearly the length of a football field and boasts as much livable volume as a six-bedroom house , .
The station 's demise did n't go completely unconsidered as the facility was being designed .
Just a few years earlier , in 1979 , NASA 's station fell out of @ @ @ @ @ @ @ guide the facility down to a controlled destruction in Earth 's atmosphere using an early flight of the space shuttle .
But that vehicle was delayed , leaving the 80-ton Skylab stranded even as solar activity picked up , warmed and expanded Earth 's atmosphere , and thereby accelerated the facility 's doom .
Related : The biggest spacecraft ever to fall uncontrolled from space As a result , the spacecraft fell on its own , out of control , leaving no way for NASA to target the pieces over remote areas or @ @ @ @ @ @ @ reduce the size of those pieces .
Instead , chunks of the station , the largest of them a massive oxygen tank .
The incident was a turning point in how people think about how large objects leave orbit .
`` In the early days of the space age , no one worried about it .
Big thing falling out of the sky , no big whoop , '' McDowell said .
`` People have gotten more and more risk-averse over the years . ''
And the longer spaceflight continues , the more @ @ @ @ @ @ @ particularly the largest of it .
The risk if the space station does fall to Earth on its own is significant , McDowell argued .
At about 400 tons , the space station is by far the heaviest human-made object ever to circle Earth .
The larger an object is , the less likely the atmosphere is to be able to fully burn it up .
And because of the space station 's outstretched , it 's vulnerable to spinning out of control , at which point rescue options would be limited , @ @ @ @ @ @ @ to an uncontrolled entry , the results would not be pretty , he said , although not nuclear-catastrophe-level grim .
It would be more like a plane crash , although with debris spread over a much broader area .
`` Worst , worst case , I guess it 's a 9/11 , right ?
, '' McDowell said .
`` Because it 's at worst case a plane crashing , part of which is in a populated area .
And that 's bad .
But it 's not . ''
So how to @ @ @ @ @ @ @ A group of engineers from NASA and Roscosmos presented a paper evaluating some disposal options at the 2017 International Astronautical Congress .
Their work is based on deorbit procedures conducted on the in 2001 ; the International Space Station is about three times heavier .
But the gist of the plan mirrors how the space station retains its altitude during normal operations .
Most commonly , a Russian will either conduct a burn while docked to the station or transfer fuel into the main service module 's thrusters to fuel the station 's @ @ @ @ @ @ @ station climbs .
In a controlled deorbit , Progress vehicles would do the same thing but in the reverse direction , lowering the station 's lowest altitude .
Depending on the precise array of spacecraft at hand , the service-module thrusters could also be used .
These carefully timed burns would maneuver the station lower at only one point in its orbit , making the re-entry more predictable and allowing managers to target the debris to the vast , .
The rest is up to the destructive power of Earth 's atmosphere .
@ @ @ @ @ @ @ risks .
If something knocks a burn off schedule , well , there goes the predictability .
The 2017 paper lays out options both for a scheduled deorbit and in response to a potential catastrophe on the space station .
If something suddenly goes unfixably wrong on the orbiting laboratory , the organizations behind the facility will have just two weeks to decide how to proceed , the group wrote .
The International Space Station 's successor may face a much smoother retirement — although still a fiery one .
Texas-based Axiom Space @ @ @ @ @ @ @ and , as commercial interest in accessing orbit grows and the ISS ages , eventually split off from the International Space Station to form its own freeflying orbital facility .
But Axiom has learned from the space station 's complicated fate and has already wrestled with how its facility will end .
The company is planning its modules to be more truly modular than those on the space station , with the capability to easily remove and replace segments anyway , flexibility in its future .
The arrangement also means that each module @ @ @ @ @ @ @ Each module is going to be designed with its own guidance , navigation and control , its own thruster capabilities , '' Maender said .
`` So they can fly essentially on their own , and then when they need to , they can separate and return through Earth 's atmosphere on their own . ''
Email Meghan Bartels at mbartels @ space.com or follow her on Twitter @ meghanbartels .
Follow us on Twitter @ Spacedotcom and on Facebook .

The International Space Station, photographed by Expedition 56 crewmembers from a Soyuz spacecraft in October 2018. NASA astronauts Andrew Feustel and Ricky Arnold and Roscosmos cosmonaut Oleg Artemyev executed a flyaround of the orbiting laboratory to take pictures of the station before returning home after spending 197 days in space.
What goes up must come down — including, sadly enough, the International Space Station .
For precisely 20 years now, the massive orbiting laboratory has constantly been home to humans, the lucky handful of Earthlings who at any given time venture into the topsy-turvy world of microgravity . But like the rest of us, the International Space Station is aging. And it can't stay in orbit on its own indefinitely — it needs a regular boost or fuel injection from visiting spacecraft. If those boosts stop or something else goes wrong, sooner or later, the lab will fall.
"Basically, any cargo ship that comes to the space station, or indeed any ferry ship, usually has surplus propellant to a certain degree," Jonathan McDowell, an astronomer at Harvard who specializes in tracking objects in and falling out of orbit, told Space.com. "They have to have propellant to do the rendezvous, and then they can sometimes have extra to do a reboost."
Related: International Space Station at 20: A photo tour
For now, those flights will continue through at least 2024. And because of the station's international nature — it's a partnership among the United States, Russia, Canada, Japan and the participating nations of the European Space Agency — the decision to retire it will always be based on both engineering and politics.
"While ISS is currently approved to operate through at least December 2024 by the international partner governments, from a technical standpoint, we have cleared ISS to fly until the end of 2028 ," NASA officials wrote in a statement to Space.com. "Additionally, our analysis has not identified any issues that would preclude us from extending beyond 2028 if needed."
But some day, the station's time will come. The facility is aging and at constant risk of impacts from space debris and micrometeorites. If humans don't retire it, eventually the hazards of space will.
The eventual fate of the space station has always been a specter for NASA and Roscosmos , Russia's federal space agency, but as time has passed, it has loomed larger on the minds of space experts.
"'Oh, we'll bring it down eventually,' the idea has always been; 'We commit to deorbiting it.' But my sense is that they didn't actually think through the details until about five years ago," McDowell said. "Until then it was like, 'La la la, it's in orbit, we're still building it, we're not going to worry about how to get rid of it.' Which maybe isn't quite the way you should do things."
The International Space Station in September 2000, just before humans took up permanent residence at the facility. (Image credit: NASA)
One major voice in changing that has been NASA's Aerospace Safety Advisory Panel, a group that evaluates the safety measures NASA is taking in spaceflight. The panel has been raising concerns for at least a decade about how the space station will end, spurred by the then-upcoming retirement of NASA's space shuttle vehicles, which could have been used to deorbit the International Space Station.
The group is still citing the issue regularly in its analyses of NASA policies.
"The panel continues to track the open work status on the planned deorbit strategy for ISS and the fine-tuning of some wording in the related space station program document," David West, a member of the panel, said during the group's quarterly meeting, which was held virtually on Oct. 1. "We will continue to monitor the progress of getting agreement on the strategy by all parties."
Scenarios for both a scheduled space station deorbit and a response if something goes very wrong are in the works, NASA confirmed, but are not yet public. "NASA is actively working with the entire International Space Station partnership on plans to safely deorbit the space station at the end of its lifetime," NASA officials wrote in a statement to Space.com.
Decades in the making
Planning the space station began in the 1980s, and while today the concept of a massive orbiting laboratory is unremarkable, at the time it was unprecedented.
"No one had any idea how to build something like this when we started out on the ISS," Christian Maender, director of in-space manufacturing and research for Houston-based company Axiom, which is planning on building its own space station by jumping off the International Space Station, told Space.com. "We built the largest peacetime engineering project ever, and by building pieces of an overall spacecraft that never actually saw each other or touched each other until they got to orbit."
All told, space station construction required 42 separate launches. The facility would weigh over 900,000 lbs. (420,000 kilograms) on Earth, is nearly the length of a football field and boasts as much livable volume as a six-bedroom house, according to NASA .
It's big.
The station's demise didn't go completely unconsidered as the facility was being designed. Just a few years earlier, in 1979, NASA's Skylab station fell out of orbit. The agency had planned to guide the facility down to a controlled destruction in Earth's atmosphere using an early flight of the space shuttle. But that vehicle was delayed, leaving the 80-ton Skylab stranded even as solar activity picked up, warmed and expanded Earth's atmosphere, and thereby accelerated the facility's doom.
Related: The biggest spacecraft ever to fall uncontrolled from space
An image showing NASA's proposed space shuttle mission to boost Skylab. Delays to the shuttle's launch meant the station fell out of orbit before a shuttle ever flew. (Image credit: NASA)
As a result, the spacecraft fell on its own, out of control, leaving no way for NASA to target the pieces over remote areas or slow the spacecraft's descent enough to reduce the size of those pieces. Instead, chunks of the station scattered across Australia , the largest of them a massive oxygen tank. The incident was a turning point in how people think about how large objects leave orbit.
"In the early days of the space age, no one worried about it. Big thing falling out of the sky, no big whoop," McDowell said. "People have gotten more and more risk-averse over the years." And the longer spaceflight continues, the more experts worry about abandoned orbital debris, particularly the largest of it.
The risk if the space station does fall to Earth on its own is significant, McDowell argued. At about 400 tons, the space station is by far the heaviest human-made object ever to circle Earth. The larger an object is, the less likely the atmosphere is to be able to fully burn it up. And because of the space station's outstretched solar arrays , it's vulnerable to spinning out of control, at which point rescue options would be limited, McDowell said.
No matter what led to an uncontrolled entry, the results would not be pretty, he said, although not nuclear-catastrophe-level grim. It would be more like a plane crash, although with debris spread over a much broader area. "Worst, worst case, I guess it's a 9/11, right?," McDowell said. "Because it's at worst case a plane crashing, part of which is in a populated area. And that's bad. But it's not asteroid-hit bad ."
How to destroy a space station (safely!)
So how to control the space station's reentry?
A group of engineers from NASA and Roscosmos presented a paper evaluating some disposal options at the 2017 International Astronautical Congress. Their work is based on deorbit procedures conducted on the Russian space station Mir in 2001; the International Space Station is about three times heavier.
But the gist of the plan mirrors how the space station retains its altitude during normal operations. Most commonly, a Russian Progress cargo vehicle will either conduct a burn while docked to the station or transfer fuel into the main service module's thrusters to fuel the station's own burn; either way, the station climbs.
In a controlled deorbit, Progress vehicles would do the same thing but in the reverse direction, lowering the station's lowest altitude. Depending on the precise array of spacecraft at hand, the service-module thrusters could also be used.
These carefully timed burns would maneuver the station lower at only one point in its orbit, making the re-entry more predictable and allowing managers to target the debris to the vast, sparsely populated southern Pacific Ocean . The rest is up to the destructive power of Earth's atmosphere. The strategy, unsurprisingly, has its risks. If something knocks a burn off schedule, well, there goes the predictability.
The 2017 paper lays out options both for a scheduled deorbit and in response to a potential catastrophe on the space station. If something suddenly goes unfixably wrong on the orbiting laboratory, the organizations behind the facility will have just two weeks to decide how to proceed, the group wrote.
A different path forward
The International Space Station's successor may face a much smoother retirement — although still a fiery one.
Texas-based Axiom Space is planning to launch new station modules beginning next year and, as commercial interest in accessing orbit grows and the ISS ages, eventually split off from the International Space Station to form its own freeflying orbital facility.
But Axiom has learned from the space station's complicated fate and has already wrestled with how its facility will end. The company is planning its modules to be more truly modular than those on the space station, with the capability to easily remove and replace segments anyway, giving the company flexibility in its future.
The arrangement also means that each module can control its own fate. "Each module is going to be designed with its own guidance, navigation and control, its own thruster capabilities," Maender said. "So they can fly essentially on their own, and then when they need to, they can separate and return through Earth's atmosphere on their own."
Email Meghan Bartels at mbartels@space.com or follow her on Twitter @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook.


livescience--2020-11-03--Cosmic bubbles may have forged dark matter, new theory suggests

Ballooning cosmic bubbles in our early universe may have led to the current abundance of dark matter , the elusive substance that tugs on the stars , yet emits no light , a new study suggests .
The theory , described Oct. 9 in the journal , may explain exactly how dark matter condensed out of the fiery soup of the early universe .
Since astronomer Fritz Zwicky first proposed the existence of in 1933 , tons of observational evidence has shown that something is lurking in the shadows , invisible to our eyes and even the latest scientific instruments @ @ @ @ @ @ @ the gravitational tug it exerts on the visible stars and galaxies astronomers observe .
The magnitude of that pull allows scientists to estimate what percentage of the universe is made of dark matter ; current estimates suggest this dark material makes up 80 % of the universe 's mass .
`` Although we know how much dark matter our universe contains , for decades now , we 've been left wondering about dark matter 's nature and origin , '' said study co-author Andrew Long , an assistant professor of physics at Rice @ @ @ @ @ @ @ matter a collection of ?
If so , what are the properties of these particles , such as their mass and spin ?
What forces do these particles exert and what interactions do they experience ?
When was the dark matter created , and what interactions played an important role in its formation ? ''
Long and physicists Michael Baker , at the University of Melbourne in Australia , and Joachim Kopp , at the Johannes Gutenberg University of Mainz in Germany , wanted to answer the last of these questions — when @ @ @ @ @ @ @ looked at the earliest period of the universe 's formation , a fraction of a nanosecond after the , a `` Wild West '' of particle creation and destruction , where particles collided and annihilated each other as quickly as they formed , Long said .
At the time , the universe was a fiery soup of extremely high-energy elementary particles , similar to the quark-gluon plasma physicists create in the biggest particle accelerators today .
This primordial soup was unimaginably hot and dense , and far too chaotic for more ordered subatomic @ @ @ @ @ @ @ form .
But this cosmic shootout did not last long .
After the universe began to expand , the plasma gradually cooled and the production of new particles came to a halt .
At the same time , particles grew further apart and their rate of collisions plummeted until their numbers remained fixed .
The particles that were left are what scientists call `` thermal relics '' , and became the matter we know and love today , such as atoms , stars , and eventually , people .
`` In addition to @ @ @ @ @ @ @ , there 's reason to imagine there were other particles present during the early universe , such as dark matter , '' Long told Live Science .
Scientists believe these hypothetical particles may also exist today as thermal relics .
In the new study , the team assumed that in the fractions of a second after the Big Bang , the plasma underwent a phase transition similar to what happens now when matter moves from one state to another , such as when bubbles of water vapor form in a pot of boiling @ @ @ @ @ @ @ form water droplets .
In this scenario , bubbles of cooled plasma formed abruptly in the boiling soup of the early universe .
These bubbles expanded and merged until the whole universe transitioned to a new phase .
`` As these droplets expanded throughout the universe , they acted like filters that sifted dark matter particles out of the plasma , '' Long said .
`` In this way , the amount of dark matter that we measure in the universe today is a direct result of this filtration in the first fractions @ @ @ @ @ @ @ . ''
The walls of these bubbles would become barriers .
Only dark matter particles with large masses would have enough energy to pass through to the other side inside the expanding bubbles and escaping the Wild West that annihilated lighter particles .
This would filter out lower mass dark matter particles and could explain the abundance of dark matter observed today .
One of the leading candidates for dark matter are Weakly Interacting Massive Particles , or WIMPs .
These hypothetical particles would weigh 10 to 100 times more than protons , @ @ @ @ @ @ @ through two of the fundamental forces of nature : and the .
Passing like specters through the universe , they could account for the missing dark matter astronomers , such as Zwicky , first noticed almost a century ago .
The search for WIMPs drove physicists to build enormous state-of-the-art detectors deep underground .
But despite decades of searching for the elusive particles , none have been found .
This led scientists in recent years to look for other dark matter particle contenders that are either lighter or heavier than WIMPs .
`` @ @ @ @ @ @ @ of our research ] is that it works for dark matter particles that are much heavier than most other candidates , such as the famous [ WIMPs ] , on which most experimental searches in the past were focused , '' Kopp , a coauthor of the paper ] , said in an interview .
`` Our work , therefore , motivates the extension of dark matter searches towards heavier masses . ''
Their work could also open up the search for dark matter to other future projects such as the Laser Interferometer @ @ @ @ @ @ @ constellation of space probes spanning millions of miles designed to detect the ripples of through space .
If the cosmic bubbles envisioned by Long and colleagues were present during the early universe , they may have left a detectable fingerprint through gravitational waves , Long said .
It 's possible some fraction of the energy created by two bubble walls colliding would produce gravitational waves detectable by future experiments .
The team plans to expand on their research to understand more about what happens when dark matter interacts with these bubble walls and @ @ @ @ @ @ @ We know dark matter is out there , but we do n't know much else , '' Baker said .
`` If it 's a new particle , then there 's a good chance that we could actually detect it in a laboratory .
We could then pin down its properties , like its mass and interactions , and learn something new and deep about the universe . ''

Ballooning cosmic bubbles in our early universe may have led to the current abundance of dark matter, the elusive substance that tugs on the stars, yet emits no light, a new study suggests.
The theory, described Oct. 9 in the journal The Physical Review Letters , may explain exactly how dark matter condensed out of the fiery soup of the early universe. Since astronomer Fritz Zwicky first proposed the existence of dark matter in 1933, tons of observational evidence has shown that something is lurking in the shadows, invisible to our eyes and even the latest scientific instruments. Dark matter leaves its fingerprint by the gravitational tug it exerts on the visible stars and galaxies astronomers observe. The magnitude of that pull allows scientists to estimate what percentage of the universe is made of dark matter; current estimates suggest this dark material makes up 80% of the universe's mass.
Related: The 11 biggest unanswered questions about dark matter
"Although we know how much dark matter our universe contains, for decades now, we've been left wondering about dark matter's nature and origin," said study co-author Andrew Long, an assistant professor of physics at Rice University in Houston. "Is dark matter a collection of elementary particles ? If so, what are the properties of these particles, such as their mass and spin? What forces do these particles exert and what interactions do they experience? When was the dark matter created, and what interactions played an important role in its formation?"
Long and physicists Michael Baker, at the University of Melbourne in Australia, and Joachim Kopp, at the Johannes Gutenberg University of Mainz in Germany, wanted to answer the last of these questions — when and how did it form? They looked at the earliest period of the universe's formation, a fraction of a nanosecond after the Big Bang started , a "Wild West" of particle creation and destruction, where particles collided and annihilated each other as quickly as they formed, Long said. At the time, the universe was a fiery soup of extremely high-energy elementary particles, similar to the quark-gluon plasma physicists create in the biggest particle accelerators today. This primordial soup was unimaginably hot and dense, and far too chaotic for more ordered subatomic particles such as protons and neutrons to form.
But this cosmic shootout did not last long. After the universe began to expand, the plasma gradually cooled and the production of new particles came to a halt. At the same time, particles grew further apart and their rate of collisions plummeted until their numbers remained fixed. The particles that were left are what scientists call "thermal relics", and became the matter we know and love today, such as atoms, stars, and eventually, people."In addition to all of the elementary particles known today, there's reason to imagine there were other particles present during the early universe, such as dark matter," Long told Live Science.
Scientists believe these hypothetical particles may also exist today as thermal relics. In the new study, the team assumed that in the fractions of a second after the Big Bang, the plasma underwent a phase transition similar to what happens now when matter moves from one state to another, such as when bubbles of water vapor form in a pot of boiling water, or steam cools down to form water droplets.
In this scenario, bubbles of cooled plasma formed abruptly in the boiling soup of the early universe. These bubbles expanded and merged until the whole universe transitioned to a new phase.
"As these droplets expanded throughout the universe, they acted like filters that sifted dark matter particles out of the plasma," Long said. "In this way, the amount of dark matter that we measure in the universe today is a direct result of this filtration in the first fractions of a second after the Big Bang."
The walls of these bubbles would become barriers. Only dark matter particles with large masses would have enough energy to pass through to the other side inside the expanding bubbles and escaping the Wild West that annihilated lighter particles. This would filter out lower mass dark matter particles and could explain the abundance of dark matter observed today.
The search continues
One of the leading candidates for dark matter are Weakly Interacting Massive Particles, or WIMPs. These hypothetical particles would weigh 10 to 100 times more than protons, but they would interact with matter only through two of the fundamental forces of nature: gravity and the nuclear weak force . Passing like specters through the universe, they could account for the missing dark matter astronomers, such as Zwicky, first noticed almost a century ago.
The search for WIMPs drove physicists to build enormous state-of-the-art detectors deep underground. But despite decades of searching for the elusive particles, none have been found. This led scientists in recent years to look for other dark matter particle contenders that are either lighter or heavier than WIMPs.
"One exciting aspect about the idea [of our research] is that it works for dark matter particles that are much heavier than most other candidates, such as the famous [WIMPs], on which most experimental searches in the past were focused," Kopp, a coauthor of the paper], said in an interview. "Our work, therefore, motivates the extension of dark matter searches towards heavier masses."
Their work could also open up the search for dark matter to other future projects such as the Laser Interferometer Space Antenna (LISA), a constellation of space probes spanning millions of miles designed to detect the ripples of gravitational waves through space.
If the cosmic bubbles envisioned by Long and colleagues were present during the early universe, they may have left a detectable fingerprint through gravitational waves, Long said. It's possible some fraction of the energy created by two bubble walls colliding would produce gravitational waves detectable by future experiments.
The team plans to expand on their research to understand more about what happens when dark matter interacts with these bubble walls and what happens when bubbles collide. "We know dark matter is out there, but we don't know much else," Baker said. "If it's a new particle, then there's a good chance that we could actually detect it in a laboratory. We could then pin down its properties, like its mass and interactions, and learn something new and deep about the universe."
Originally published on Live Science.