livescience--2020-11-06--The world's largest iceberg is on a collision course with an Antarctic penguin refuge

The may be on a collision course with a wildlife haven in the South Atlantic Ocean , researchers at the .
If the gargantuan berg becomes grounded near South Georgia island ( a British overseas territory and one of the South Sandwich Islands ) , it could crush animals and block off foraging routes for thousands of penguins and seals — potentially disrupting the island 's ecosystem for a decade or more , according to BAS scientists .
`` Ecosystems can and will bounce back of course , but there 's a danger here that if this iceberg gets stuck @ @ @ @ @ @ @ years , '' Geraint Tarling , an ecologist with BAS , .
The iceberg in question is known simply as A68a .
The massive slab calved from 's Larsen C Ice Shelf in July 2017 , initially measuring more than 2,300 square miles ( 6,000 square kilometers ) in area — an ice raft large enough to hold the five boroughs of New York City five times over .
Since then , A68a has been drifting ever northward into warmer waters , gradually shedding little chunks of itself along the way .
( @ @ @ @ @ @ @ of ice still measured about 2,000 square miles , or 5,100 square km , in area , ) .
Recently , satellite images have spotted the berg ( which now looks like a hand with one pointing finger ) drifting directly toward South Georgia , a small , mountainous island that serves as the breeding ground for hundreds of thousands of seals and penguins .
With a surface area similar to A68a ’ s , the island ecosystem could be seriously disrupted if the berg makes landfall .
In addition to injuring animals @ @ @ @ @ @ @ presence could block the normal feeding and foraging routes that animals use during their crucial chick- and pup-rearing seasons , Tarling said .
`` The actual distance [ the animals ] have to travel to find food ( fish and krill ) really matters , '' Tarling explained .
`` If they have to do a big detour , it means they 're not going to get back to their young in time to prevent them starving to death in the interim . ''
There 's still a chance that ocean currents could @ @ @ @ @ @ @ rather than directly into it , Peter Fretwell , a mapping specialist with BAS , said in the statement .
If that 's the case , then the pups and penguins of South Georgia could even see some dietary benefits ; according to Tarling , the vast quantities of dust riding aboard A68a could fertilize nearby ocean , sending those nutrients up the food chain to fish , penguins and seals .
`` This plankton also draws in carbon from the atmosphere , partially offsetting , '' Tarling said .
Harbinger of icy @ @ @ @ @ @ @ The destiny of iceberg A68a remains to be seen .

Iceberg A68a (shaped like a pointing finger) is bearing down on the island of South Georgia, putting thousands of animals at risk.
The world's largest iceberg may be on a collision course with a wildlife haven in the South Atlantic Ocean, researchers at the British Antarctic Society (BAS) reported . If the gargantuan berg becomes grounded near South Georgia island (a British overseas territory and one of the South Sandwich Islands), it could crush animals and block off foraging routes for thousands of penguins and seals — potentially disrupting the island's ecosystem for a decade or more, according to BAS scientists.
"Ecosystems can and will bounce back of course, but there's a danger here that if this iceberg gets stuck, it could be there for 10 years," Geraint Tarling, an ecologist with BAS, said in a statement .
The iceberg in question is known simply as A68a. The massive slab calved from Antarctica 's Larsen C Ice Shelf in July 2017, initially measuring more than 2,300 square miles (6,000 square kilometers) in area — an ice raft large enough to hold the five boroughs of New York City five times over. Since then, A68a has been drifting ever northward into warmer waters, gradually shedding little chunks of itself along the way. (As of early April, the hunk of ice still measured about 2,000 square miles, or 5,100 square km, in area, Live Science previously reported ).
Recently, satellite images have spotted the berg (which now looks like a hand with one pointing finger) drifting directly toward South Georgia, a small, mountainous island that serves as the breeding ground for hundreds of thousands of seals and penguins.
With a surface area similar to A68a’s, the island ecosystem could be seriously disrupted if the berg makes landfall. In addition to injuring animals during the collision, the iceberg's presence could block the normal feeding and foraging routes that animals use during their crucial chick- and pup-rearing seasons, Tarling said.
Large numbers fo whales, seals and penguins feed off the coast of South Georgia. (Image credit: Martin Collins)
"The actual distance [the animals] have to travel to find food (fish and krill) really matters," Tarling explained. "If they have to do a big detour, it means they're not going to get back to their young in time to prevent them starving to death in the interim."
There's still a chance that ocean currents could carry A68a around the island's coast rather than directly into it, Peter Fretwell, a mapping specialist with BAS, said in the statement. If that's the case, then the pups and penguins of South Georgia could even see some dietary benefits; according to Tarling, the vast quantities of dust riding aboard A68a could fertilize nearby ocean plankton , sending those nutrients up the food chain to fish, penguins and seals.
"This plankton also draws in carbon from the atmosphere, partially offsetting human CO2 emissions ," Tarling said.
Harbinger of icy doom, or floating nutritional supplement? The destiny of iceberg A68a remains to be seen.
Originally published on Live Science.


What are cytokines?

Cytokines are molecules that allow your cells to talk to each other , and are crucial for healthy immune system function .
Too many cytokines , however , can have a negative effect and result in what 's known as a `` cytokine storm . ''
These small signaling molecules are produced by many different immune cells , such as neutrophils ( some of the first cells to travel to an infection site ) , mast cells ( responsible for allergic reactions ) , macrophages , B-cells and T-cells , according to a 2014 review published in the journal Frontiers @ @ @ @ @ @ @ cells `` kind of like a Wi-Fi signal , '' said Joyce Wu , an immunobiologist at the University of Arizona in Tucson .
They then bind to specific receptors on both immune and non-immune cells , and may signal the cell to adjust how it grows or behaves .
Nearly every organ of the body contains cells with cytokine receptors .
Chemokines are cytokines that act like a beacon directing immune cells where to go .
In this way , chemokines help immune cells find and destroy whatever harmful invader has entered @ @ @ @ @ @ @ from immune cells , they can also come from non-immune cells , said Mandy Ford , an immunologist at Emory University in Atlanta , Georgia .
Endothelial cells , which are the cells lining the inside of blood vessels , and epithelial cells , which are the cells covering the surface of organs , skin and other tissue , can also send cytokines around the body .
When a pathogen , or harmful invader enters the body , immune cells , cytokines and organs respond by working together like an orchestra , Ford @ @ @ @ @ @ @ notice the pathogen is like the conductor .
That cell directs all the other cells by creating and sending out messages ( cytokines ) to the rest of the organs or cells in the body ( the orchestra members ) , which then respond as directed .
`` The initiation of cytokine secretion tells the rest of the immune cells , and also non-immune cells in the body that there is a pathogen present , and an immune response should be occurring , '' Ford said .
One of the immune responses cytokines @ @ @ @ @ @ @ inflame tissue by directing the cell walls of blood vessels to become more porous by reducing cell-to-cell contact , Ford said .
Blood vessels will then leak blood into the surrounding tissue , allowing immune cells to travel via the leaked fluid to the damaged area , and start the healing process .
While cytokine production mainly occurs when the body is infected by a pathogen , cytokine-induced inflammatory responses also happen when tissues are physically damaged , such as if you tripped and cut your knee on the sidewalk .
Are cytokines @ @ @ @ @ @ @ system ?
Our immune system can be divided into two categories : the innate immune system and the adaptive immune system .
The innate immune system refers to the immunity that you 're born with , which targets general health threats , while adaptive immunity refers to acquired immunity , which targets more specific pathogens .
Cytokines are `` at the crossroads of bridging the communication between the innate and adaptive immune responses , '' Ford said .
That 's because the amount and type of cytokines that cells secrete differ depending on @ @ @ @ @ @ @ differences help the immune system appropriately tailor its response to be innate or adaptive .
Certain cytokines can stimulate either the innate immune system , adaptive one , or a mix of both depending on the infection .
Cytokines can also direct brain cells to release chemicals that tell your body that you 're sick , prompting you to rest and avoid activities that could further expose you to pathogens .
`` Tiredness , lethargy , malaise and just that kind of achy feeling is the impact of cytokines on our bodies , @ @ @ @ @ @ @ the innate immune system would n't know when to activate because there would be no indication of a threat .
Once activated , innate immune cells do n't secrete cytokines intended for any specific receptors at first , Ford said .
Rather , secreted cytokines will target the entire body , causing fever , achy joints and fatigue , according to a 2007 study published in the journal International Anesthesiology Clinics .
The adaptive immune system will eventually secrete specific cytokines that target and activate T-cells in order to fine-tune the immune response @ @ @ @ @ @ @ a 2010 study from The Journal of Allergy and Clinical Immunology .
Cytokines signal the adaptive immune system to activate when the innate immune system fails to subdue an infection .
While the innate immune system is good at warding off general health threats , it may fail to destroy foreign pathogens .
Cytokines direct the adaptive immune system to produce pathogen-specific antigens that quickly identify the pathogen so the immune system can destroy it .
The cytokine response is slow , and for good reason , Wu said .
A 2020 editorial @ @ @ @ @ @ @ describes how a rapid immune response in which loads of cytokines are released would cause hyperinflammation , which can lead to shock and organ damage .
The slow initial response of the innate immune system prevents the release of too many cytokines at one time , avoiding collateral damage to the body , according to a 2007 study published in the journal Nature Public Health Emergency Collection .
The fine-tuned T-cell response can then attack the infection without causing excess harm to the body .
Cytokines help your body fight off and kill @ @ @ @ @ @ @ the body and create what is known as a `` cytokine storm . ''
It 's a `` simple analogy to a weather-type storm where it 's too much of a good thing , '' Ford said .
A cytokine storm may occur when too many pathogens enter the body at once , or if the body secretes the wrong type of cytokine early in the immune response , in which case the excessive cytokines ca n't accurately direct the immune system to clear out the pathogen .
Because nearly every organ has @ @ @ @ @ @ @ the body is susceptible to the negative effects of a cytokine storm .
A normal release of cytokines causes blood vessel walls to become leakier in order to promote healing of damaged tissue via inflammation , but too many cytokines may cause blood vessels to become overly porous and result in low blood pressure .
That , in turn , depletes organs of oxygen and could eventually cause death , Ford said .
Patients with sepsis or uncontrolled bacterial infections typically experience a cytokine storm , and it 's also a symptom of @ @ @ @ @ @ @ as described in the JAMA Internal Medicine editorial .
A cytokine storm is essentially an uncontrolled immune response that leads to reduced oxygen in the blood , fluid build-up in the lungs , difficulty breathing , and many of the other symptoms observed in COVID-19 illnesses , Ford said .
Whether induced by COVID-19 or not , cytokine storms can also cause neurological issues .
The brain is naturally protected from harmful chemicals thanks to the blood-brain barrier .
But cytokines are much smaller than cells , so they can slip through the @ @ @ @ @ @ @ have been known to cause symptoms such as headache , migraine , decreased appetite , increased need for sleep and overwhelming fatigue , according to a 2009 review published in the journal Psychiatry .
Some research suggests that cytokine storms are a major reason for illness and death among COVID-19 patients , according to the JAMA Internal Medicine editorial .
A 2020 study published in the journal Clinical Infectious Diseases found the cytokine inhibiting drug tocilizumab has been shown to reduce mortality in COVID-19 patients on ventilators by 45 % .
Related : @ @ @ @ @ @ @ against the coronavirus Cytokine levels can also influence the care COVID-19 patients receive .
The presence and amount of certain cytokines can predict the survivability of COVID-19 cases , reported a recent study published in Nature Medicine .
This can help doctors create an effective treatment protocol depending on cytokine severity .
Although the mechanisms underpinning the severity of COVID-19 are still poorly understood , a recent review published in the journal Cardiorenal Medicine found that properly timed anti-inflammatory strategies may help reduce the severity of cytokine storms and can improve a patient @ @ @ @ @ @ @ 's how doctors and professors at the Yale School of Medicine describe cytokine storms .
• Learn more about how cancer researchers use cytokines as therapy , from the Center for Cancer Research .
• Watch this video explaining the relationship between cytokine storms and COVID-19 severity from the Johns Hopkins Bloomberg School of Public Health .

Cytokines are molecules that allow your cells to talk to each other, and are crucial for healthy immune system function. Too many cytokines, however, can have a negative effect and result in what's known as a "cytokine storm."
These small signaling molecules are produced by many different immune cells, such as neutrophils (some of the first cells to travel to an infection site), mast cells (responsible for allergic reactions), macrophages, B-cells and T-cells, according to a 2014 review published in the journal Frontiers in Immunology.
Cytokines radiate out from cells "kind of like a Wi-Fi signal," said Joyce Wu, an immunobiologist at the University of Arizona in Tucson. They then bind to specific receptors on both immune and non-immune cells, and may signal the cell to adjust how it grows or behaves. Nearly every organ of the body contains cells with cytokine receptors.
Chemokines are cytokines that act like a beacon directing immune cells where to go. In this way, chemokines help immune cells find and destroy whatever harmful invader has entered the body.
While cytokines typically come from immune cells, they can also come from non-immune cells, said Mandy Ford, an immunologist at Emory University in Atlanta, Georgia. Endothelial cells, which are the cells lining the inside of blood vessels, and epithelial cells, which are the cells covering the surface of organs, skin and other tissue, can also send cytokines around the body.
How do cytokines work?
When a pathogen, or harmful invader enters the body, immune cells, cytokines and organs respond by working together like an orchestra, Ford said. The first immune cell to notice the pathogen is like the conductor. That cell directs all the other cells by creating and sending out messages (cytokines) to the rest of the organs or cells in the body (the orchestra members), which then respond as directed.
"The initiation of cytokine secretion tells the rest of the immune cells, and also non-immune cells in the body that there is a pathogen present, and an immune response should be occurring," Ford said.
One of the immune responses cytokines may elicit is inflammation. Cytokines help inflame tissue by directing the cell walls of blood vessels to become more porous by reducing cell-to-cell contact, Ford said. Blood vessels will then leak blood into the surrounding tissue, allowing immune cells to travel via the leaked fluid to the damaged area, and start the healing process.
While cytokine production mainly occurs when the body is infected by a pathogen, cytokine-induced inflammatory responses also happen when tissues are physically damaged, such as if you tripped and cut your knee on the sidewalk.
Are cytokines part of the innate or adaptive immune system?
Our immune system can be divided into two categories: the innate immune system and the adaptive immune system. The innate immune system refers to the immunity that you're born with, which targets general health threats, while adaptive immunity refers to acquired immunity, which targets more specific pathogens.
Cytokines are "at the crossroads of bridging the communication between the innate and adaptive immune responses," Ford said. That's because the amount and type of cytokines that cells secrete differ depending on the type of pathogen, and those differences help the immune system appropriately tailor its response to be innate or adaptive. Certain cytokines can stimulate either the innate immune system, adaptive one, or a mix of both depending on the infection.
Cytokines can also direct brain cells to release chemicals that tell your body that you're sick, prompting you to rest and avoid activities that could further expose you to pathogens. "Tiredness, lethargy, malaise and just that kind of achy feeling is the impact of cytokines on our bodies," Ford said.
Related: 11 surprising facts about the immune system
Without cytokines, the innate immune system wouldn't know when to activate because there would be no indication of a threat. Once activated, innate immune cells don't secrete cytokines intended for any specific receptors at first, Ford said. Rather, secreted cytokines will target the entire body, causing fever, achy joints and fatigue, according to a 2007 study published in the journal International Anesthesiology Clinics. The adaptive immune system will eventually secrete specific cytokines that target and activate T-cells in order to fine-tune the immune response toward the specific introduced pathogen, reported a 2010 study from The Journal of Allergy and Clinical Immunology.
Cytokines signal the adaptive immune system to activate when the innate immune system fails to subdue an infection. While the innate immune system is good at warding off general health threats, it may fail to destroy foreign pathogens. Cytokines direct the adaptive immune system to produce pathogen-specific antigens that quickly identify the pathogen so the immune system can destroy it.
The cytokine response is slow, and for good reason, Wu said. A 2020 editorial published in the journal JAMA Internal Medicine describes how a rapid immune response in which loads of cytokines are released would cause hyperinflammation, which can lead to shock and organ damage. The slow initial response of the innate immune system prevents the release of too many cytokines at one time, avoiding collateral damage to the body, according to a 2007 study published in the journal Nature Public Health Emergency Collection. The fine-tuned T-cell response can then attack the infection without causing excess harm to the body.
Infographic of a cell secreting cytokines to a target cell which then elicits a response. Proper cytokine secretion is crucial for the immune system to function. (Image credit: Shutterstock)
When are cytokines a bad thing?
Cytokines help your body fight off and kill infections, but too many cytokines overwhelm the body and create what is known as a "cytokine storm." It's a "simple analogy to a weather-type storm where it's too much of a good thing," Ford said.
A cytokine storm may occur when too many pathogens enter the body at once, or if the body secretes the wrong type of cytokine early in the immune response, in which case the excessive cytokines can't accurately direct the immune system to clear out the pathogen. Because nearly every organ has cytokine receptors, almost every part of the body is susceptible to the negative effects of a cytokine storm.
A normal release of cytokines causes blood vessel walls to become leakier in order to promote healing of damaged tissue via inflammation, but too many cytokines may cause blood vessels to become overly porous and result in low blood pressure. That, in turn, depletes organs of oxygen and could eventually cause death, Ford said.
Related: Woman with COVID-19 developed a rare brain condition. Doctors suspect a link.
Patients with sepsis or uncontrolled bacterial infections typically experience a cytokine storm, and it's also a symptom of some diseases, such as COVID-19, as described in the JAMA Internal Medicine editorial. A cytokine storm is essentially an uncontrolled immune response that leads to reduced oxygen in the blood, fluid build-up in the lungs, difficulty breathing, and many of the other symptoms observed in COVID-19 illnesses, Ford said.
Whether induced by COVID-19 or not, cytokine storms can also cause neurological issues. The brain is naturally protected from harmful chemicals thanks to the blood-brain barrier. But cytokines are much smaller than cells, so they can slip through the brain's protective membrane. Cytokine storms have been known to cause symptoms such as headache, migraine, decreased appetite, increased need for sleep and overwhelming fatigue, according to a 2009 review published in the journal Psychiatry.
Treating COVID-19 cytokine storms
Some research suggests that cytokine storms are a major reason for illness and death among COVID-19 patients, according to the JAMA Internal Medicine editorial. A 2020 study published in the journal Clinical Infectious Diseases found the cytokine inhibiting drug tocilizumab has been shown to reduce mortality in COVID-19 patients on ventilators by 45%.
Related: Treatments for COVID-19: Drugs being tested against the coronavirus
Cytokine levels can also influence the care COVID-19 patients receive. The presence and amount of certain cytokines can predict the survivability of COVID-19 cases, reported a recent study published in Nature Medicine. This can help doctors create an effective treatment protocol depending on cytokine severity. Although the mechanisms underpinning the severity of COVID-19 are still poorly understood, a recent review published in the journal Cardiorenal Medicine found that properly timed anti-inflammatory strategies may help reduce the severity of cytokine storms and can improve a patient's health when infected.
Additional resources:


livescience--2020-11-06--Rare wolf spider presumed extinct turns up on British military base

A 2-inch-long ( 5 centimeters ) spider thought to be extinct in Great Britain is actually alive and thriving on a British military base .
A program manager at the Surrey Wildlife Trust rediscovered the great fox-spider ( Alopecosa fabrilis ) on an undeveloped portion of a military installation in Surrey , England , after a two-year search .
The last time the spider was seen before this in Britain was in 1993 , or 27 years ago .
`` It 's a gorgeous , if you 're into that kind of thing , '' the program manager Mike Waite @ @ @ @ @ @ @ , a family of arachnids that hunts down its prey rather than building webs .
The spider is nocturnal , which makes it an elusive quarry for spider enthusiasts .
According to The Guardian , Waite used aerial photography of the military installation to find bare patches where the spiders like to hunt .
His search in these sandy spots paid off after many fruitless nights .
`` As soon as my torch fell on it I knew what it was .
I was elated , '' Waite said .
`` With coronavirus @ @ @ @ @ @ @ and downs this year , and I also turned 60 , so it was a good celebration of that . ''
Waite found several male spiders , one female and possibly some immature spiderlings , though the latter were difficult to identify conclusively .
The adult spiders have gray-and-brown furry bodies .
They can spin silk , but instead of making webs , they use that silk to line the burrows that they dig in order to hibernate over the winter .
Great fox-spiders are critically endangered , but they are also found @ @ @ @ @ @ @ coastal sand dunes in Holland and Denmark , according to The Guardian .
Waite wonders whether the spiders are also quietly surviving on Britain 's coastlines .
`` It makes me think how hard have we looked for it on our coasts ?
Have we been looking hard enough ? ''
he told The Guardian .
The Surrey Wildlife Trust manages thousands of acres of undeveloped land in the Surrey area to protect wildlife .
Ministry of Defence sites are also prime real estate for animals , because they 're left relatively undisturbed @ @ @ @ @ @ @ occur there .
For security reasons , the researchers are keeping confidential the identity of the site where they found the great fox-spiders , but it consists of scrubby heartland that also provides a home for native birds , snakes , lizards and butterflies .
`` Many people are unaware of the size and diversity of the Defence estate and its tremendous wildlife richness , '' Rich Lowey , the head of technical services at the Defense Infrastructure Organization , .
`` It has generally been protected from agricultural intensification and urban development @ @ @ @ @ @ @ sanctuary for many of the country 's most rare and endangered species and habitats . ''
Waite now plans to continue his survey for the spiders in order to estimate the size of their population .

Great fox-spiders immobilize their prey by injecting them with venom that liquifies the internal organs of the insect.
A 2-inch-long (5 centimeters) spider thought to be extinct in Great Britain is actually alive and thriving on a British military base.
A program manager at the Surrey Wildlife Trust rediscovered the great fox-spider (Alopecosa fabrilis) on an undeveloped portion of a military installation in Surrey, England, after a two-year search. The last time the spider was seen before this in Britain was in 1993, or 27 years ago.
"It's a gorgeous spider , if you're into that kind of thing," the program manager Mike Waite told The Guardian .
Related: Goliath birdeater: Images of a colossal spider
Nocturnal hunter
The great fox-spider is a wolf spider , a family of arachnids that hunts down its prey rather than building webs. The spider is nocturnal, which makes it an elusive quarry for spider enthusiasts. According to The Guardian, Waite used aerial photography of the military installation to find bare patches where the spiders like to hunt. His search in these sandy spots paid off after many fruitless nights.
"As soon as my torch fell on it I knew what it was. I was elated," Waite said. "With coronavirus, there have been lots of ups and downs this year, and I also turned 60, so it was a good celebration of that."
Waite found several male spiders, one female and possibly some immature spiderlings, though the latter were difficult to identify conclusively.
Related: Photos: Wolf spiders caught having threesomes
The adult spiders have gray-and-brown furry bodies. They can spin silk, but instead of making webs, they use that silk to line the burrows that they dig in order to hibernate over the winter. Great fox-spiders are critically endangered, but they are also found on the European mainland, particularly on coastal sand dunes in Holland and Denmark, according to The Guardian. Waite wonders whether the spiders are also quietly surviving on Britain's coastlines.
"It makes me think how hard have we looked for it on our coasts? Have we been looking hard enough?" he told The Guardian.
Conserving space for wildlife
The Surrey Wildlife Trust manages thousands of acres of undeveloped land in the Surrey area to protect wildlife. Ministry of Defence sites are also prime real estate for animals, because they're left relatively undisturbed other than the military training exercises that occur there. For security reasons, the researchers are keeping confidential the identity of the site where they found the great fox-spiders, but it consists of scrubby heartland that also provides a home for native birds, snakes, lizards and butterflies.
"Many people are unaware of the size and diversity of the Defence estate and its tremendous wildlife richness," Rich Lowey, the head of technical services at the Defense Infrastructure Organization, said in a statement . "It has generally been protected from agricultural intensification and urban development, so it now provides a vital sanctuary for many of the country's most rare and endangered species and habitats."
Waite now plans to continue his survey for the spiders in order to estimate the size of their population.
Originally published on Live Science.


livescience--2020-11-06--Massive great white shark Unama'ki  spotted south of Miami

One of the largest great white sharks ever tagged was just spotted swimming south of Miami , Florida , according to NBC Miami .
Unama'ki `` pinged '' at 5:46 a.m .
ET off of Key Largo , south of Miami on Thursday ( Nov. 5 ) , which means that its dorsal fin broke the surface of the water , sending a signal to a satellite , alerting researchers of its whereabouts , according to a previous article from Florida Today .
Unama'ki was first tagged in Nova Scotia in September ; in the indigenous language of the Mi'kmaq @ @ @ @ @ @ @ of the fog . ''
With a length of 15 feet and 5 inches ( 4.7 meters ) and a weight of 2,076 pounds ( 942 kilograms ) , she is the second largest white shark ever tagged by Ocearch , a nonprofit organization that tags and tracks large marine animals .
But she 's not the only impressive beast out there .
Great white sharks are the largest predatory fish on the planet and grow to an average of 15 feet ( 4.6 m ) , according to National Geographic .
Some @ @ @ @ @ @ @ 5,000 Ibs .
( 2,268 kg ) and to grow to more than 20 feet ( 6 m ) .
Over a month ago , researchers with Ocearch also discovered and tagged a 17-foot-long ( 5 m ) heavy female great white shark — weighing 3,541 lbs .
( 1,606 kg ) — off the coast of Nova Scotia that they called the `` queen of the ocean , '' according to a previous Live Science report .
She was officially named Nukumi , after a legendary wise grandmother figure from the indigenous @ @ @ @ @ @ @ as `` vulnerable '' by the International Union for Conservation of Nature .
As top predators of the ocean , `` great white sharks are central to the functioning of ecosystems and the maintenance of biodiversity , '' according to Ocearch .
Researchers hope that Unama'ki will lead them to a site where she gives birth and thereby reveal a previously unknown white shark nursery , according to Ocearch .
But great white shark whereabouts are n't always clear .
The majestic sea creatures can only be tracked once they break the surface @ @ @ @ @ @ @ a different amount of time at the surface , according to Ocearch .
You can track Unama'ki 's whereabouts , or at least every time she breaks the surface , here .

One of the largest great white sharks ever tagged was just spotted swimming south of Miami, Florida, according to NBC Miami.
Unama'ki "pinged" at 5:46 a.m. ET off of Key Largo, south of Miami on Thursday (Nov. 5) , which means that its dorsal fin broke the surface of the water, sending a signal to a satellite, alerting researchers of its whereabouts, according to a previous article from Florida Today.
Unama'ki was first tagged in Nova Scotia in September; in the indigenous language of the Mi'kmaq people, her name means "land of the fog." With a length of 15 feet and 5 inches (4.7 meters) and a weight of 2,076 pounds (942 kilograms), she is the second largest white shark ever tagged by Ocearch, a nonprofit organization that tags and tracks large marine animals.
Related: Image gallery: Great White sharks
But she's not the only impressive beast out there. Great white sharks are the largest predatory fish on the planet and grow to an average of 15 feet (4.6 m), according to National Geographic. Some have been found to weigh up to 5,000 Ibs. (2,268 kg) and to grow to more than 20 feet (6 m).
Over a month ago, researchers with Ocearch also discovered and tagged a 17-foot-long (5 m) heavy female great white shark — weighing 3,541 lbs. (1,606 kg) — off the coast of Nova Scotia that they called the "queen of the ocean," according to a previous Live Science report. She was officially named Nukumi, after a legendary wise grandmother figure from the indigenous Mi'kmaq people.
Great whites are classified as "vulnerable" by the International Union for Conservation of Nature. As top predators of the ocean, "great white sharks are central to the functioning of ecosystems and the maintenance of biodiversity," according to Ocearch.
Researchers hope that Unama'ki will lead them to a site where she gives birth and thereby reveal a previously unknown white shark nursery, according to Ocearch.
But great white shark whereabouts aren't always clear. The majestic sea creatures can only be tracked once they break the surface, and each shark tends to spend a different amount of time at the surface, according to Ocearch.
You can track Unama'ki's whereabouts, or at least every time she breaks the surface, here.
Originally published on Live Science.


livescience--2020-11-06--Coronavirus outbreak: Live updates

Coronavirus outbreak: Live updates

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90-year-old woman in the UK receives first dose of Pfizer vaccine, FDA review confirms vaccine is safe and effective A 90-year-old woman (who will turn 91 next week) became the first in the world to be given Pfizer's coronavirus vaccine outside of clinical trials, according to the BBC. Margaret Keenan, who is originally from Northern Ireland, was given the vaccine at the University Hospital in Coventry, England. She received the first of 800,000 doses expected to be administered in the U.K. in the coming weeks, according to the BBC. "I feel so privileged to be the first person vaccinated against Covid-19," Keenan said, according to the BBC."It's the best early birthday present I could wish for because it means I can finally look forward to spending time with my family and friends in the new year after being on my own for most of the year." "My advice to anyone offered the vaccine is to take it. If I can have it at 90, then you can have it too," she added. Up to four million doses of Pfizer's vaccine is expected to be given to people in the U.K. by the end of the month. Meanwhile, a 53-page Food and Drug Administration (FDA) review published Tuesday (Dec. 8) confirmed that Pfizer's vaccine is safe and effective, according to The Washington Post.
Pfizer's COVID-19 vaccine starts to work just 10 days after 1st dose Pfizer's new COVID-19 vaccine starts to protect people from the novel coronavirus just 10 days after the first dose, according to new documents from the U.S. Food and Drug Administration (FDA). The documents were released on Tuesday (Dec. 8), two days before a meeting of the FDA's vaccine advisory panel, which will vote on whether to recommend authorization of the vaccine in the U.S, Live Science reported . The FDA analyzed data from Pfizer's phase 3 clinical trial, which included some 44,000 people in the United States, Brazil, Argentina, Germany and Turkey, about half of whom received the vaccine while the other half received a placebo. Both groups received two shots, 21 days apart. About 10 days after the first dose, there was a noticeable drop-off in new COVID-19 cases in the vaccine group compared with the placebo group, indicating that even one dose provides some protection, the report said. However, scientists don't know how long the protection from a single dose will last, so it will still be important for people to receive two shots, according to The New York Times . Overall, the vaccine was 52% effective after the first dose and 95% effective after the second dose, the report said.
People with significant allergies should avoid Pfizer vaccine, UK warns The U.K.'s Regulatory Agency is advising people with a history of "significant" allergic reactions to avoid Pfizer's coronavirus vaccine, after two National Health Service members developed severe allergic reactions to it on Tuesday (Dec. 8), Live Science reported. "As is common with new vaccines the MHRA (Medicines and Healthcare products Regulatory Agency) have advised on a precautionary basis that people with a significant history of allergic reactions do not receive this vaccination after two people with a history of significant allergic reactions responded adversely yesterday," Stephen Powis, the national medical director for England's National Health Service said in a statement on Wednesday (Dec. 9). Both workers have a history of severe allergies and carry adrenaline auto injectors (such as EpiPens) around with them, according to The Guardian. Shortly after receiving the vaccine, both NHS workers developed anaphylaxis-like symptoms, or severe allergic reactions, but have recovered after receiving treatment. The MHRA will investigate further and Pfizer and BioNTech will support their investigation, according to Reuters. "Allergic reaction occurs with quite a number of vaccines, and perhaps even more frequently with drugs. So it is not unexpected," Stephen Evans, a professor of pharmacoepidemiology at the London School of Hygiene and Tropical Medicine said in remarks to journalists published by Britain's Science Media Center. “What would be wise, as the MHRA have already advised, would be for anyone who has known severe allergic reaction such that they need to carry an EpiPen, to delay having a vaccination until the reason for the allergic reaction has been clarified," he said. For the general population this does not mean that they would need to be anxious about receiving the vaccination, he added. "One has to remember that even things like marmite [a quintessential British food spread] can cause unexpected severe allergic reactions.”
Canada approves Pfizer's COVID-19 vaccine Canada has authorized Pfizer's new COVID-19 vaccine, with the first doses expected to be administered there as early as next week. Health Canada, the country's health regulatory agency, said in a statement on Wednesday (Dec. 9) that it had determined that the vaccine "meets the Department's stringent safety, efficacy and quality requirements for use in Canada," according to CTV News . "We expect vaccines to arrive maybe as early as Monday [Dec. 14]. It takes time to prepare the vaccine," said Maj.-Gen. Dany Fortin, the top military general leading the vaccine rollout for the Public Health Agency of Canada, according to CTV News. The first doses could be administered by the middle of next week, he said. Canada is the third country in the world to authorize the Pfizer vaccine, following the United Kingdom and Bahrain. The country should receive up to 249,000 doses of the vaccine by the end of December, and has purchased 20 million doses total, with the option to purchase more, CTV News reported.
Daily COVID-19 death toll in the U.S. reaches record-high, surpassed 9/11 On Wednesday (Dec. 9), the U.S. recorded 3,124 new COVID-19 deaths, the highest daily death toll to date, according to CNN . In comparison, 2,977 people were killed in the 9/11 attacks. The U.S. has now recorded 280,488 deaths related to the virus, according to The COVID Tracking Project . A forecast from the U.S. Centers for Disease Control and Prevention predicts that the total death toll can increase to between 332,000 and 362,000 by January 2, according to CNN. There are currently 106,671 people hospitalized with the virus in the U.S.; 20,903 of them are currently in the ICU and 7,621 are currently on a ventilator, according to the COVID Tracking Project. On Thursday (Dec. 10), the Vaccines and Related Biological Products Advisory Committee is set to meet to discuss an emergency use authorization for the Pfizer-BioNTech coronavirus vaccine.
FDA panel recommends authorization of Pfizer's COVID-19 vaccine A panel of experts for the Food and Drug Administration (FDA) has recommended that the agency authorize Pfizer's new COVID-19 vaccine in the United States. On Thursday (Dec. 10), the panel voted 17 to 4 to recommend that the vaccine receive emergency use authorization (EUA) for people ages 16 and older, according to The New York Times . The FDA typically follows the advice of its panels, and so today's vote is an important step towards the vaccine's authorization. It is anticipated that the agency will officially authorize the vaccine on Saturday (Dec. 12), the Times reported. Several countries have already authorized Pfizer's vaccine, including Canada, the United Kingdom and Bahrain.
Vaccine approval could come this weekend, as U.S. continues to record high daily death tolls On Thursday (Dec. 10), the U.S. recorded another 2,902 COVID-19 deaths, a day after the country set a record of 3,253 deaths, according to Reuters . “Probably for the next 60 to 90 days, we’re going to have more deaths per day than we had on 9/11 or we had at Pearl Harbor,” Dr. Robert Redfield, the director of the U.S. Centers for Disease Control and Prevention, told the Council on Foreign Relations on Thursday, according to Reuters. "The reality is the vaccine approval this week is not going to really impact that, I think, to any degree for the next 60 days." On Thursday, the Vaccines and Related Biological Products Advisory Committee discussed, voted and recommended that the Food and Drug Administration (FDA) should grant an emergency use authorization for Pfizer's coronavirus vaccine. The Pfizer vaccine has already been approved in the U.K. and in Canada, and FDA approval for use in the U.S. could come this weekend.
Australia abandons local COVID-19 vaccine after it caused false-positive HIV tests An Australian COVID-19 vaccine that had shown promising results in early trials is being abandoned after researchers found that the shot caused false-positive results on HIV tests. On Friday (Dec. 11), Australian officials said they had canceled an order for some 51 million doses of the vaccine, which was being developed by The University of Queensland and CSL Ltd., a local biotech company, according to The New York Times . In an early trial with 216 participants, the vaccine appeared to be safe and to produce a robust immune response against COVID-19, according to a statement from CSL . But some volunteers falsely tested positive for HIV, which officials feared would undermine trust in the vaccine, the Times reported. The vaccine contained small fragments of an HIV protein, which helped stabilize the vaccine. Some of the participants developed antibodies against these fragments, and these antibodies triggered false positive results on some HIV tests. It's important to note that there is no way for the vaccine to cause an HIV infection, because it contains harmless fragments of the virus.
ICU nurse in New York becomes first person in the US to receive a coronavirus vaccine outside of clinical trials New York, the worst-hit state at the start of the pandemic, just became the first to administer a coronavirus vaccine outside of clinical trials, kicking off a long, massive effort to vaccinate the American people, Live Science reported. Around 9 a.m. E.T. on Monday (Dec. 14), the very first dose of Pfizer and BioNTech's coronavirus vaccine was given to Sandra Lindsay, an intensive care nurse in Long Island Jewish Medical Center in Queens, New York, according to The New York Times. This comes as the U.S. continues to battle a massive wave of the virus that has more than 109,000 people currently hospitalized, according to The COVID Tracking Project. Since the start of the pandemic, New York has recorded more than 780,000 cases of COVID-19 and more than 35,100 deaths, according to The Times. "This vaccine is exciting because I believe this is the weapon that will end the war," Gov. Andrew Cuomo said during a live broadcast of the first vaccination. "It's the beginning of the last chapter of the book, but now we just have to do it."
FDA analysis confirms Moderna's vaccine is safe and effective, emergency authorization is likely to come Friday A new briefing document from the Food and Drug Administration (FDA) released on Tuesday (Dec. 15) confirmed that Moderna's COVID-19 vaccine is safe and effective, according to NPR . Moderna's COVID-19 vaccine is 94% effective and has "a favorable safety profile," according to the document. A panel of experts is set to meet on Thursday (Dec. 17) to discuss the effectiveness and safety of the vaccine and vote on whether or not the FDA should grant emergency approval to the vaccine. Last week, the same panel voted that the FDA should grant emergency approval to Pfizer's coronavirus vaccine; the authorization came a day late and the first doses were given on Monday (Dec. 15). The FDA will likely approve Moderna's vaccine for emergency use on Friday (Dec. 18), according to The New York Times .
FDA authorizes first over-the-counter COVID-19 test The U.S. Food and Drug Administration (FDA) has authorized the first over-the-counter COVID-19 test, which can be done at home and does not need a prescription. The test, made by the Australia-based company Ellume, provides results in as little as 20 minutes, according to a statement from the FDA . It is a "lateral flow antigen test," meaning it works in a similar way to a home pregnancy test, by running a "liquid sample along a surface with reactive molecules," the FDA said. The test works in conjunction with a smartphone app. Users take a nasal swab and place their sample in an analyzer, which communicates to the smartphone app via Bluetooth. The results are delivered through the app, and also reported to public health authorities (based on a user's zip code) through a secure cloud connection, the company said . Ellume is ramping up production of its test, and expects to produce three million tests in January 2021, and 20 million within the first half of 2021.
A wild mink tested positive for the coronavirus, it may be the first wild animal to have a confirmed case A wild mink in Utah may be the first "free-ranging, native wild animal" confirmed to be infected with SARS-CoV-2, according to the U.S. Department of Agriculture (USDA), Live Science reported. The mink was found near a mink farm and likely picked up the infection from the farmed mink. There's no evidence that the virus spread to other minks or wild animals; but if the virus does begin circulating in wild animals, it could pick up mutations that COVID-19 vaccines may not protect well against if it spreads back to humans, according to the report. "If it does [establish a reservoir], then we've got a long-term issue here, where this virus has the potential to be with us for millennia," Sarah Olson, associate director of the health program at the Wildlife Conservation Society, told Vox. The U.S. Department of Agriculture's Animal and Plant Health Inspection Service has screened other animal species for the virus near mink farms in Utah, Michigan and Wisconsin, but all of them have tested negative so far, according to a statement.
An FDA advisory panel will meet today to vote on whether to recommend Moderna's coronavirus vaccine for emergency approval On Thursday (Dec. 17), a Food and Drug Administration (FDA) advisory committee will meet to determine whether to recommend that Moderna’s coronavirus vaccine for emergency approval, according to The New York Times . This panel, composed of independent experts, will vote on whether to recommend the vaccine after hearing from the company, FDA scientists and the public, according to The Times. Last week, the same panel of experts met to discuss Pfizer’s coronavirus vaccine and voted to recommend emergency authorization; the authorization came the next day. There have now been more than 16.9 million cases of COVID-19 in the U.S. and more than 307,000 deaths, according to the Johns Hopkins dashboard . There are currently 113,090 people hospitalized across the country with more than 21,900 of them in the ICU and 7,778 on a ventilator, according to The COVID Tracking Project .
California becomes new epicenter of COVID-19 in U.S. California, once praised for its early pandemic response, is now the new U.S. hotspot for COVID-19 infections. The state has reported an alarming surge in cases, breaking previous records for daily cases. On Thursday (Dec. 17), the state reported some 50,000 COVID-19 infections in 24 hours, and nearly 100,000 in 48 hours, according to The Washington Post . That's more than the daily cases reported in many countries, including India, Germany and Britain, the Post reported. The state also set a record for daily deaths on Thursday, with 379 fatalities reported, up from the previous high of 293. Capacity in intensive care units has also dropped dramatically, with hospitals in Southern California reporting zero percent capacity on Thursday. "I want to be very clear: Our hospitals are under siege, and our model shows no end in sight," said Christina Ghaly, director of Los Angeles County's Department of Health Services, the Post reported.
FDA expected to authorize Moderna's vaccine on Friday The U.S. Food and Drug Administration is expected to authorize Moderna's COVID-19 vaccine on Friday (Dec. 18). Once authorized, it will be the second coronavirus vaccine to get the green light from the agency in just a week, with Pfizer's vaccine gaining authorization on Dec. 11. Moderna is expected to begin shipping 5.9 million doses of its vaccine on Sunday (Dec. 20), with the first deliveries arriving Monday (Dec. 21), according to The New York Times . Unlike the Pfizer vaccine, Moderna's vaccine does not require storage in extremely cold temperatures, and states are hoping to distribute the vaccine to rural hospitals and community health centers, the Times reported.
COVID-19 cases continue to surge across the U.S. There have now been more than 17 million cases of COVID-19 in the U.S. and more than 300,000 deaths, according to The COVID Tracking Project . There are currently 114,237 people hospitalized across the country and 21,900 people in the ICU. California is facing a massive surge in cases; the state reported 41,012 new COVID-19 cases and 300 new deaths on Thursday (Dec. 17), according to the state's COVID-19 dashboard . By comparison, at the start of November, California was reporting a seven-day average of 4,183 cases, compared to an average of 38,774 on Thursday, according to CNN . "We're experiencing an explosive and very deadly surge," Dr. Barbara Ferrer, Los Angeles County Public Health Director said, according to CNN. Intensive care unit beds are rapidly filling up across the state; there are only 1,234 ICU beds left available in California, according to the dashboard. Current closures across California are impacting around 98% of the state's population, according to CNN.
London and southeast England are under an emergency lockdown Following concerns of a new version of the coronavirus that might be more transmissible, London and most of southeast England are now under an emergency lockdown, according to The New York Times . Prime Minister Boris Johnson announced the lockdown on Saturday (Dec. 19) citing concerns that the mutated virus — which was detected a couple of weeks ago in southeast England — may be as much as 70% more transmissible than previous versions, according to the Times. The new version of the coronavirus is detected in more than 60% of new infections in London and have also been detected in several other countries, according to the Times. But it's not yet clear if this coronavirus version is any more infectious than the last and thorough analyses will need to be conducted before conclusions are made, scientists cautioned. In South Africa, a similar version of the virus has been found in up to 90% of new cases detected since mid-November, according to The Times . It's common for viruses to mutate, and this particular coronavirus has mutated many times since the start of the pandemic. But experts told The Times that it would take years for the virus to mutate enough such that it would make the current vaccines developed to fight COVID-19 ineffective.
Biden gets Pfizer's COVID-19 vaccine President-elect Joe Biden received a dose of Pfizer's new COVID-19 vaccine on Monday (Dec. 21), according to The New York Times . He received the shot on camera at the Christiana Hospital in Newark, Delaware. "I'm doing this to demonstrate that people should be prepared when it's available to take the vaccine. There's nothing to worry about," Biden said.
Antarctica has its 1st COVID-19 outbreak The first COVID-19 cases have been reported in Antarctica , meaning the disease has now spread to every continent in the world. On Tuesday (Dec. 22), Chilean officials reported an outbreak of 36 COVID-19 cases at the Chilean research base General Bernardo O'Higgins Riquelme on the Antarctic Peninsula, according to the BBC . Of these, 26 cases were military personnel and 10 were maintenance workers, the BBC reported. All of these cases have been evacuated from Antarctica to Punta Arenas, Chile, according to The Guardian . Antarctica had been COVID-19 free up until the current outbreak. The continent has no permanent residents, but about 1,000 people, including scientists and other workers, stayed there this past winter, The Guardian reported.
Live updates will continue in 2021!


livescience--2020-11-07--Amazing images: The best science photos of the week

Each week at Live Science we find the most interesting and informative articles we can .
Along the way , we uncover some amazing and cool images .
Here you 'll discover the most incredible photos we found this week , and the remarkable stories behind them .
A 2-inch-long ( 5 centimeters ) spider thought to be extinct in Great Britain is actually alive and thriving on a British military base .
A program manager at the Surrey Wildlife Trust rediscovered the great fox-spider ( Alopecosa fabrilis ) on an undeveloped portion of a military installation in Surrey , @ @ @ @ @ @ @ The last time the spider was seen before this in Britain was in 1993 , or 27 years ago .
The great fox-spider is a , a family of arachnids that hunts down its prey rather than building webs .
The spider is nocturnal , which makes it an elusive quarry for spider enthusiasts .
According to The Guardian , the investigator used aerial photography of the military installation to find bare patches where the spiders like to hunt .
Ultimately , he found several male spiders , one female and possibly some @ @ @ @ @ @ @ identified a lava world so dramatic that it might boast a thin regional atmosphere of vaporized rock where it is closest to its star .
That is called K2-141b and was originally discovered in 2017 .
The world is about half again as big as Earth but orbits so close to its star , which is one class smaller than our own , that it completes several loops each Earth-day with the same surface permanently facing the star .
Now , scientists predict those factors mean that two-thirds of the surface of K2-141b @ @ @ @ @ @ @ that not only is part of the world covered in a , but some of that rock may even evaporate away into the atmosphere .
`` All rocky planets , including Earth , started off as molten worlds but then rapidly cooled and solidified , '' Nicolas Cowan , a planetary scientist at McGill University in Canada and a coauthor on the new paper , .
`` Lava planets give us a rare glimpse at this stage of planetary evolution . ''
[ Read more : This bizarre planet could have supersonic winds @ @ @ @ @ @ @ The may be on a collision course with a wildlife haven in the South Atlantic Ocean , researchers at the .
If the gargantuan berg becomes grounded near South Georgia island ( a British overseas territory and one of the South Sandwich Islands ) , it could crush animals and block off foraging routes for thousands of penguins and seals — potentially disrupting the island 's ecosystem for a decade or more , according to BAS scientists .
The iceberg in question is known simply as A68a .
The massive slab calved from @ @ @ @ @ @ @ 2017 , initially measuring more than 2,300 square miles ( 6,000 square kilometers ) in area — an ice raft large enough to hold the five boroughs of New York City five times over .
Satellite images show it currently on a direct course with South Georgia , a small , mountainous island that serves as the breeding ground for hundreds of thousands of seals and penguins .
`` Ecosystems can and will bounce back of course , but there 's a danger here that if this iceberg gets stuck , it could @ @ @ @ @ @ @ Geraint Tarling , an ecologist with BAS , .
[ Read more : The world 's largest iceberg is on a collision course with an Antarctic penguin refuge ] One of the largest ever tagged was just spotted swimming south of Miami , Florida , .
Unama'ki `` pinged '' at 5:46 a.m .
ET off of Key Largo , south of Miami on Thursday ( Nov. 5 ) , which means that its dorsal fin broke the surface of the water , sending a signal to a satellite , alerting researchers of @ @ @ @ @ @ @ article from Florida Today .
Unama'ki was first tagged in Nova Scotia in September ; in the indigenous language of the Mi'kmaq people , her name means `` land of the fog . ''
With a length of 15 feet and 5 inches ( 4.7 meters ) and a weight of 2,076 pounds ( 942 kilograms ) , she is the second largest white shark ever tagged by Ocearch , a nonprofit organization that tags and tracks large marine animals .
Researchers hope that Unama'ki will lead them to a site where she @ @ @ @ @ @ @ unknown white shark nursery , .
No limb to stand on Archaeologists have discovered the rare burial of a young child who was laid to rest 8,000 years ago without arm and leg bones , a new study finds .
The child , who was no older than 8 , was buried on what is now Alor Island , Indonesia .
During the burial ceremony , the long bones in the child 's arms and legs were removed and disposed elsewhere , and part of the child 's face was painted with , @ @ @ @ @ @ @ the ancient world .
This is n't the only burial from this region with missing arm and leg bones .
`` The lack of long bones is a practice that has been documented in several other burials from a similar time period in Java , Borneo and Flores , but this is the first time we have seen it in a child 's burial , '' said lead researcher Sofia Samper Carro , a lecturer of archaeology at Australian National University in Canberra .
`` We do n't know why long bone removal @ @ @ @ @ @ @ some aspect of the belief system of the people who lived at this time . ''
[ Read more : Rare ancient burial contains child whose arms and legs were removed ] Fast radio bursts ( ) are some of the most energetic — and most brief — blasts of light in the universe .
These mysterious pulses appear and disappear in milliseconds , yet pack more energy than the sun unleashes in three days .
Now , after 13 years of searching , researchers have finally traced one back to its origins @ @ @ @ @ @ @ series of three papers published today ( Nov. 4 ) in the journal , researchers from the United States and Canada report the detection of an FRB that originates not in some far-flung galaxy , but 30,000 light-years away in the northern sky of the Milky Way .
Not only is this the first FRB ever detected within our own galaxy , but also the first to originate from a known object in the universe — in this case , a highly-magnetized stellar corpse known as a .
This burnt-out star — named @ @ @ @ @ @ @ evidence of the origins of FRBs after more than a decade of mystery , Daniele Michilli , a co-author of one of the new studies , told Live Science .
[ Read more : Mysterious 'fast radio burst ' traced to a known object in the Milky Way for the first time ever ] Silently moving in the wilderness of the , ancient hunter-gatherers stalked a herd of vicuña .
The hunters threw stone projectile points with ease , hitting some of the beasts and leading the rest to scatter .
The vicuñas @ @ @ @ @ @ @ and the skilled hunters — both females and males — went to examine their wins .
This somewhat hypothetical account is in stark contrast to the accepted history of such hunter-gatherers : ancient men hunted big game , while women gathered herbs and plants .
But a recently discovered 9,000-year-old burial of a female hunter , and analyses of other hunter burials , suggests that early hunter-gatherer women in the ancient Americas hunted big game just as much as men did , according to a study published on Nov. 4 in the journal @ @ @ @ @ @ @ rich artifact assemblage , '' researchers said , including a hunting toolkit with projectile points and flakes .
The burial is thought to belong to a hunter-gatherer who , based on examination of tooth development , died between the ages of 17 and 19 .
A detailed analysis of in the young hunter-gatherer 's teeth confirmed that she was a female .
[ Read more : Ancient burial of fierce female hunter ( and her weapons ) discovered in Peru ] More than a century after it was last seen , a spectacularly @ @ @ @ @ @ @ rediscovery of the Voeltzkow 's chameleon ( Furcifer voeltzkowi ) on Oct. 30 in the journal .
The animal , endemic to Madagascar , was last seen in 1913 — and until now , no one had ever seen a female Voeltzkow 's chameleon .
The females turn out to be a striking sight .
They can change colors , and at their most brilliant display a pattern of red dots and a streak of purple against a background of black and white .
`` The Voeltzkow 's chameleon adds color and beauty @ @ @ @ @ @ @ that even when all seems lost , a great adventure can rekindle hope even for species we have n't seen since Woodrow Wilson was president , '' Don Church , the president of Global Wildlife Conservation , said in a statement .
`` Now we have so much to learn about this extraordinary reptile , including how we can best save it from extinction . ''
[ Read more : 'Lost ' chameleon rediscovered after a century in hiding .
And it 's spectacular . ]
With an estimated 300 active volcanoes on @ @ @ @ @ @ @ monitor them all to send out early warnings before they erupt .
Measuring volcanic gas emissions is also no easy task .
Now researchers have designed specially-adapted drones to help gather data from the active in Papua New Guinea ( PNG ) .
The drones could help local communities monitor nearby volcanoes and forecast future eruptions .
Their measurements could also tell us more about the most inaccessible , highly active volcanoes on the planet and how volcanoes contribute to the .
[ Read more : Drones are flying straight into volcanoes , @ @ @ @ @ @ @ the platypus 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 @ @ @ @ @ @ @ and this is the first evidence of biofluorescence in egg-laying mammals , also known as monotremes , scientists reported in a new study .
• Earth from Above : 101 Stunning Images from Orbit • From Big Bang to Present : Snapshots of Our Universe Through Time

Each week at Live Science we find the most interesting and informative articles we can. Along the way, we uncover some amazing and cool images. Here you'll discover the most incredible photos we found this week, and the remarkable stories behind them.
Gargantuan "growlers"
(Image credit: RAF)
In July 2017, a gargantuan iceberg spanning five times the area of New York's five boroughs snapped off the coast of Antarctica and began to drift northward.
Though its edges have crumbled considerably since then, the iceberg — named A-68a — is still the largest on Earth , and it's currently barreling toward an island wildlife refuge in the South Atlantic Ocean. New aerial footage taken by the United Kingdom's Royal Air Force (RAF) reveals just what that island might be up against.
For starters, the RAF footage really drives home how massive this ice giant is. (As of early April, A-68a measured about 2,000 square miles, or 5,100 square kilometers, in area, Live Science previously reported ). The berg's steep walls tower 100 feet (30 meters) above the sea, according to RAF News , and are gouged with tunnels, fissures and caves. Huge chunks of ice, or "growlers," are rapidly cracking off on all sides, leaving behind a trail of debris that could impede boat traffic in the future.
[Read more: World's largest iceberg still barreling toward penguin habitat, new footage confirms ]
Clear head, nine arms, can't lose
(Image credit: Kyodo News via Getty Images)
A nine-armed octopus caught off Japan's coast nearly ended up being dinner, until the family preparing it noticed its extra limb and sent it to a museum instead, according to news sources. While unusual, this extra appendage — which wasn't fully formed, but a small offshoot on a regular arm — isn't unheard of in octopuses, said Michael Vecchione, an invertebrate zoologist at the Smithsonian's National Museum of Natural History in Washington, D.C., who was not involved with this octopus's discovery.
Octopuses are capable of regenerating their arms, but "sometimes regeneration doesn't work quite right," Vecchione told Live Science. "If an arm gets damaged, it might regenerate wrong; it could wind up with extra tissue growing out, and that extra tissue could turn into an arm."
The nine-armed oddity was caught in a trap with three other octopuses on Nov. 13 in Shizugawa Bay, in the northeastern town of Minamisanriku, Japan, according to The Mainichi , a Japanese newspaper.
[Read more: Rare 9-armed octopus found off Japan coast ]
The sound of a supernova
(Image credit: NASA)
In space, nobody can hear you scream — or explode, or collapse, or slowly collide with a neighboring galaxy. But now, thanks to a new " data sonification " program at NASA, you can at least get a sense of what some of the most extreme phenomena in the universe might sound like when converted to sound played by Earthly instruments.
To hear what that sounds like, we turn to NASA's Chandra X-ray center — which has been imaging distant galaxies with its Chandra X-ray observatory for 20 years now. In their new initiative, Chandra researchers have taken three iconic images from their archives and translated different frequencies of light into different pitches of sound.
The first video shows the crab nebula (a supernova remnant powered by a windy neutron star , shown above). In NASA's data sonification of the nebula, X-ray light (blue and white) is represented by brass instruments; optical light (purple) is played by string instruments; and infrared light (pink) is represented by woodwinds. The sounds converge near the center of the nebula, where a rapidly swirling pulsar is blasting gas and radiation in all directions. Listen to this cosmic symphony (and two others) at the link below.
[Read more: This is what a supernova sounds like, according to NASA ]
Pterosaur's missing cousin
(Image credit: Rodolfo Nogueira)
Nearly nothing is known about the family tree of pterosaurs — iconic reptiles that flew alongside the dinosaurs . These now-extinct beasts appear in the fossil record with already developed wings and senses adapted for flying, with researchers having nary a clue about their immediate evolutionary history.
But now, the pterosaur's family tree has a new branch; an enigmatic group of small reptiles, known as lagerpetids, might be the closest-known pterosaur relatives on record, the researchers of a new study say.
Unlike pterosaurs, however, lagerpetids did not fly. "Now, we have an idea of what a flightless pterosaur relative would look like," study co-researcher Sterling Nesbitt, an associate professor of geosciences at Virginia Tech, told Live Science.
[Read more: Missing link in pterosaur origins discovered ]
The changing face of ice
(Image credit: NOAA/Photo courtesy of Caitlin Bailey, GFOE, The Hidden Ocean 2016: Chukchi Borderlands)
From vanishing sea ice to blistering air temperatures to zombie fires , climate change is reshaping the Arctic. And that transformation may be permanent, researchers said on Tuesday (Dec. 8) at the annual meeting of the American Geophysical Union (AGU).
The Arctic has warmed and melted at an alarmingly accelerating pace over the last 15 years, and the impacts are accumulating so rapidly that "there's no reason to think that in 30 years anything will be as it is today," Rick Thoman, an Alaska climate specialist with the International Arctic Research Center (IARC) at the University of Alaska Fairbanks (UAF), said at the conference, held virtually due to the COVID-19 pandemic, on Tuesday.
This year's news was not good: June snow cover across the Eurasian Arctic was at its lowest in 54 years; coastal permafrost erosion is increasing; and glaciers and ice sheets in Greenland continued a trend "of significant ice loss," according to the report.
[Read more: Dramatic transformation of the Arctic landscape may be permanent ]
Starship down
(Image credit: SpaceX)
SpaceX's Starship spaceflight system just took a big step on its path to Mars. The latest Starship prototype, a shiny silver vehicle known as SN8, launched on an epic high-altitude test flight on Dec. 9, taking off at 5:45 p.m. EST from SpaceX's facility near the South Texas village of Boca Chica.
The goal was to soar about 7.8 miles (12.5 kilometers) into the sky, perform some complex aerial maneuvers — including a "belly flop" like the one the final Starship will perform when coming back to Earth on operational flights — and then land safely near the launch stand. The 165-foot-tall (50 meters) SN8 appeared to notch all of these big milestones, except for the final one: The vehicle hit its landing mark but came in too fast, exploding in a dramatic fireball 6 minutes and 42 seconds after liftoff.
SN8's rapid unplanned disassembly did nothing to dampen the spirits of SpaceX founder and CEO Elon Musk, who was thrilled by the results of today's flight.
[Read more: SpaceX's Starship SN8 prototype soars on epic test launch, with explosive landing ]
Amazonian universe
Billions of lasers shot from a helicopter flying over the Brazilian Amazon Rainforest have detected a vast network of long-abandoned circular and rectangular-shaped villages dating from 1300 to 1700, a new study finds.
The round villages all had remarkably similar layouts, with elongated mounds circling a central plaza, like marks on a clock. "These latter elongated mounds, when seen from above, look like the rays of the sun, which gives them the common name of 'Sóis,'" the Portuguese word for "suns," the researchers wrote in the study.
The discovery is part of a new archaeological focus on the pre-Columbian Amazon. Within the past 20 years, researchers have learned that the rainforest's southern rim was home to a great diversity of soil-sculpting cultures that engineered the landscape before the Europeans arrived. Within the past decade, scientists have uncovered the remnants of so-called "mound villages," which are shaped as circles or rectangles, and connected by road networks.
[Read more: Archaeologists find vast network of Amazon villages laid out like the cosmos ]
The sky is falling
(Image credit: ESA)
Have you ever seen 40,000 shooting stars blaze across the sky at the same time?
If you'd like to, the European Space Agency (ESA) is offering you two options: Either stare at the night sky for about half a million years as our solar system drifts steadily through the Milky Way (some patience required) — or, watch a new 60-second time-lapse simulation of the same thing, courtesy of the ESA's Gaia space observatory.
In the new simulation, 40,000 stars — all located within 325 light-years of Earth's sun — whiz through space, leaving long trails of light behind them. Each point of light represents one real object in the Milky Way, and each shining trail shows that object's projected movement through the galaxy over the next 400,000 years. Brighter, faster streaks are located closer to our solar system, while dimmer, slower ones live much farther away.
[Read more: Epic time-lapse shows what the Milky Way will look like 400,000 years from now ]
Gold in the garden
(Image credit: © The Trustees of the British Museum)
A family in England was weeding their garden when they unearthed a valuable treasure — a buried hoard of gold coins dating back to the 1400s, depicting English monarchs from Edward IV to Henry VIII.
The hoard — a stash of 63 gold coins and one silver coin — contains money minted over a period of nearly 100 years, from the late 15th to the 16th centuries. Four of the coins feature Henry VIII and, curiously, one of the initials of three of his wives: Catherine of Aragon, Anne Boleyn and Jane Seymour.
Upon finding the cache, the family, in the New Forest district of Hampshire, a county in southeastern England, notified the British Museum, which runs the Portable Antiquities Scheme (PAS). This program partners with local people who find historical artifacts in the United Kingdom, so the findings can be documented and studied, the British Museum said in a statement Thursday (Dec. 10).
[Read more: Gold coin stash from time of Henry VIII found in English garden ]
Enigma of the deep
(Image credit: Florian Huber/WWF)
Divers trying to remove old fishing nets from the Baltic sea have accidentally stumbled on a Nazi code-making machine. The Enigma machine, as it's called, looks a bit like a typewriter. In fact, the diver who found the device on the ocean floor initially thought that's what the artifact was, according to AFP . But the diving team, on assignment for the conservation group World Wide Fund for Nature (WWF), quickly realized that they had something much stranger.
During World War II, Enigma machines were used to encode German military messages, in hopes of preventing Allied powers from learning about troop movements and other plans. The devices consisted of a keyboard and a series of rotors that did the encoding. The rotors substituted different letters for the ones typed in; different Enigma machines used between three and eight rotors, which moved independently after each keystroke so that the same initial letter typed into the machine would appear as multiple different letters in the final code.
The Enigma machine found by the WWF diving crew was at the bottom of the Bay of Gelting in northeast Germany. It had three rotors, making it the type used on warships, not U-boats. That suggests that the machine may have been tossed overboard in the final days of World War II, in an attempt to keep the technology out of enemy hands, historian Jann Witt of the German Naval Association told the DPA news agency.
[Read more: Nazi 'Enigma' machine found at the bottom of the Baltic Sea ]
Originally published on Live Science.


livescience--2020-11-07--What was the largest empire in the world?

, which seems as good an authority as any , the answer is the Achaemenid Empire in 480 B.C .
Also known as the Persian Empire , it 's estimated that 44 % of the world 's population was ruled from the Achaemenid throne in what is now modern-day Iran , making it history 's largest empire by this measure .
However , perhaps unsurprisingly , not everyone agrees .
That 's because the share of the global population is only one way to measure the expanse of an empire , and some question whether it 's really fair to @ @ @ @ @ @ @ different time periods .
For example , when the Achaemenid Empire was at its height , there were only 112.4 million people alive .
The British ruled over a comparatively meager quarter of the world 's population in 1901 , but by then the global population had swelled to 1.6 billion people .
Is it reasonable to compare the British and Achaemenid empires with this metric ?
Or are we comparing apples to oranges ?
That 's without getting into the pros and cons of the other ways to measure size : largest @ @ @ @ @ @ @ ; largest army ; largest gross domestic product ; and so on .
Instead , we should use a metric to measure long-term influence and stability , said Martin Bommas , an Egyptologist and director of the Macquarie University History Museum in Sydney , Australia , because it 's one thing to embark on warring campaigns to amass land , but it takes a different set of logistical skills and infrastructure to keep and administer those territories .
`` For me , the metric would be counted in years , '' Bommas told @ @ @ @ @ @ @ 's Third Reich ; it took a lot of territory to rival the Romans , but no one would call it an empire because it only lasted six years and in a period of total war.
” '' I think that to be classed as an empire , you need to have a period of peace to bring prosperity , '' Bommas added .
That prosperity can then be exploited so that resources and wealth can be sent back to the motherland , Bommas said .
That 's where Mongol Empire fails as @ @ @ @ @ @ @ empire .
While it can legitimately claim to be the largest contiguous land empire , it did n't last that long .
Just 88 years after its founding , the empire was cut into four separate khanates because Genghis Khan ’ s descendants squabbled over the line of succession , and most of the Mongol Empire 's relatively brief unity was spent engaged in battle with outsiders , aggressively expanding its borders at what proved to be an unsustainable rate .
The British Empire may not have been contiguous , but it beats @ @ @ @ @ @ @ under its control .
`` It was so massive that we almost struggle to comprehend it today , '' said Bommas .
`` The sun literally did n't set on the British Empire and it was n't just land that it controlled ; the seas were dominated by the British . ''
The British Empire emerged in the late 1500s when the then-separate kingdoms of England and Scotland established their first overseas colonies in the Americas and the Caribbean .
On a technical level , you could make an argument that the British @ @ @ @ @ @ @ dramatically diminished sense — through its continued possession of 14 relatively minor overseas territories including Gibraltar and the Falkland Islands .
There are also 16 independent countries , also known as Commonwealth Realms , where Queen Elizabeth II is still the head of state , including Australia , Belize , Canada , New Zealand , Papua New Guinea and several Caribbean countries .
But most agree it ended in 1997 , when the United Kingdom handed Hong Kong back to China , Bommas said .
`` Prince Charles said that Hong Kong marked @ @ @ @ @ @ @ `` It was the last major colony in the empire , so I 'm happy to go along with him on that one . ''
If we also agree with Prince Charles , then the British Empire lasted roughly 400 years , which means that though the British conquered more parts of the globe than anyone else , they still ca n't be called the largest empire when measured by longevity .
The , governed from modern-day Turkey , outlasted the British Empire because it ruled for at least 600 years .
But @ @ @ @ @ @ @ agree that the Roman Empire persisted when it split in two to create the Western Roman Empire and the Eastern Roman Empire — the latter of which lasted the longest at close to 1,500 years .
`` If you look at it through years lasted , the Romans won this competition hands down , '' Bommas said .

According to Guinness World Records , which seems as good an authority as any, the answer is the Achaemenid Empire in 480 B.C. Also known as the Persian Empire, it's estimated that 44% of the world's population was ruled from the Achaemenid throne in what is now modern-day Iran, making it history's largest empire by this measure.
However, perhaps unsurprisingly, not everyone agrees. That's because the share of the global population is only one way to measure the expanse of an empire, and some question whether it's really fair to use that metric when comparing empires from different time periods. For example, when the Achaemenid Empire was at its height, there were only 112.4 million people alive. The British ruled over a comparatively meager quarter of the world's population in 1901 , but by then the global population had swelled to 1.6 billion people. Is it reasonable to compare the British and Achaemenid empires with this metric? Or are we comparing apples to oranges?
Related: Why did Rome fall?
That's without getting into the pros and cons of the other ways to measure size: largest land mass; largest contiguous land mass; largest army; largest gross domestic product; and so on.
Instead, we should use a metric to measure long-term influence and stability, said Martin Bommas, an Egyptologist and director of the Macquarie University History Museum in Sydney, Australia, because it's one thing to embark on warring campaigns to amass land, but it takes a different set of logistical skills and infrastructure to keep and administer those territories.
"For me, the metric would be counted in years," Bommas told Live Science. "Look at Hitler's Third Reich; it took a lot of territory to rival the Romans, but no one would call it an empire because it only lasted six years and in a period of total war.”
"I think that to be classed as an empire, you need to have a period of peace to bring prosperity," Bommas added. That prosperity can then be exploited so that resources and wealth can be sent back to the motherland, Bommas said.
That's where Genghis Khan's Mongol Empire fails as a contender for the world's largest empire. While it can legitimately claim to be the largest contiguous land empire , it didn't last that long. Just 88 years after its founding, the empire was cut into four separate khanates because Genghis Khan’s descendants squabbled over the line of succession, and most of the Mongol Empire's relatively brief unity was spent engaged in battle with outsiders, aggressively expanding its borders at what proved to be an unsustainable rate.
Genghis Khan's Mongol Empire in 1227 and at its greatest extent in 1279. (Image credit: Shutterstock)
The British Empire may not have been contiguous, but it beats the Mongols in terms of land mass under its control. "It was so massive that we almost struggle to comprehend it today," said Bommas. "The sun literally didn't set on the British Empire and it wasn't just land that it controlled; the seas were dominated by the British."
The British Empire emerged in the late 1500s when the then-separate kingdoms of England and Scotland established their first overseas colonies in the Americas and the Caribbean. On a technical level, you could make an argument that the British Empire still exists — albeit in a dramatically diminished sense — through its continued possession of 14 relatively minor overseas territories including Gibraltar and the Falkland Islands. There are also 16 independent countries, also known as Commonwealth Realms, where Queen Elizabeth II is still the head of state, including Australia, Belize, Canada, New Zealand, Papua New Guinea and several Caribbean countries. But most agree it ended in 1997, when the United Kingdom handed Hong Kong back to China, Bommas said.
"Prince Charles said that Hong Kong marked the end," Bommas said. "It was the last major colony in the empire, so I'm happy to go along with him on that one."
If we also agree with Prince Charles, then the British Empire lasted roughly 400 years, which means that though the British conquered more parts of the globe than anyone else, they still can't be called the largest empire when measured by longevity. The Ottoman Empire , governed from modern-day Turkey, outlasted the British Empire because it ruled for at least 600 years. But it was the Romans — assuming you agree that the Roman Empire persisted when it split in two to create the Western Roman Empire and the Eastern Roman Empire — the latter of which lasted the longest at close to 1,500 years.
"If you look at it through years lasted, the Romans won this competition hands down," Bommas said.
Originally published on Live Science.


livescience--2020-11-08--Planned satellite constellation poses a collision threat, NASA says: Reports

NASA has voiced `` substantial concerns '' about a planned constellation of broadband satellites , saying the commercial spacecraft would increase the risk of collisions in an important slice of Earth orbit .
On Oct. 30 , NASA submitted an official comment letter to the U.S. Federal Communications Commission ( FCC ) regarding a request by Texas-based company AST & Science to operate a network of up to 243 satellites about 450 miles ( 720 kilometers ) above Earth 's surface , as Ars Technica 's Eric Berger .
This constellation , called SpaceMobile , will provide broadband service directly @ @ @ @ @ @ @ according to the company 's plan .
To pull this off , the SpaceMobile will sport very large antennas — gear that covers an area of about 9,700 square feet ( 900 square meters ) , Berger wrote .
The SpaceMobile satellites will therefore have quite big cross sections , boosting the probability of conjunctions , or close flybys , with other spacecraft in their neck of the orbital woods , states the NASA letter , which you can find .
And the space agency cares quite a bit about that orbital region @ @ @ @ @ @ @ '' a group of 10 Earth-observation missions operated by NASA , the U.S. Geological Survey and several international partners that travel around Earth in the same path .
The A-Train 's average altitude is 438 miles ( 705 km ) , but the satellites get as close to Earth as 429 miles ( 690 km ) and as far away as 460 miles ( 740 km ) .
`` Therefore , the AST constellation would be essentially collocated with the A-Train if the proposed orbit altitude is chosen , '' reads the comment @ @ @ @ @ @ @ Fonder , NASA representative to the Commercial Space Transportation Interagency Group .
NASA 's calculations suggest that gliding safely among the SpaceMobile satellites might require 1,500 `` mitigation actions , '' or spacecraft maneuvers , and 15,000 `` planning activities '' per year for the A-Train 's handlers , Fonder wrote .
That equates to about four maneuvers and 40 planning activities every day .
In addition , `` this is an orbit regime that has a large debris object density ( resulting from the Fengyun 1-C ASAT test and the Iridium 33-COSMOS @ @ @ @ @ @ @ conjunctions with debris objects , '' the letter adds , referring , respectively , to a and a between one operational satellite and one dead one .
NASA would therefore like AST & Science to `` consider alternative orbit regimes for this constellation , perhaps notably below the A-Train constellation , in order to allow for a more manageable safety-of-flight situation for a constellation of such large satellites , '' the letter reads .
AST & Science , for its part , maintains that SpaceMobile wo n't pose an undue collision risk .
@ @ @ @ @ @ @ of the network 's satellites has just a 1-in-5,000 chance of colliding with another spacecraft at random , without any mitigation actions , over its operational life , Berger reported in another Ars Technica story last week .
If AST & Science does get 243 satellites aloft , the probability of a random smashup constellation-wide would therefore be about 1 in 20 .
AST & Science founder Abel Avellan also stressed that the company knows what it 's doing , even though it has yet to launch any satellites to orbit .
( @ @ @ @ @ @ @ of a SpaceMobile spacecraft and plans to launch it in the second half of 2021 , Avellan told Berger . )
`` We 're not a bunch of cowboys launching satellites , '' Avellan told Berger .
`` This is a serious , well-funded project . ''
Indeed , AST & Science recently snared about $ 128 million in a recent `` Series B '' investment round , Avellan told Berger , and the company 's partners include Samsung , Rakuten and the Vodafone Group .
You can learn much more about SpaceMobile @ @ @ @ @ @ @ Science 's constellation plan in Berger 's two stories , which you can find and .
SpaceMobile is not the only big broadband constellation in the offing , of course .
Amazon aims to launch to low Earth orbit , and OneWeb has already lofted 74 internet satellites for a planned constellation of at least 648 spacecraft ( though the company recently , potentially complicating those ambitions ) .
SpaceX has launched nearly 900 satellites for its and is already rolling out a public beta testing campaign for its broadband service .
And @ @ @ @ @ @ @ to come : Elon Musk 's company already has FCC permission to operate 12,000 Starlink satellites in Earth orbit .
Starlink craft fly considerably lower than the A-train , zooming through space about 340 miles ( 550 km ) above the planet 's surface .
Mike Wall is the author of `` `` ( Grand Central Publishing , 2018 ; illustrated by Karl Tate ) , a book about the search for alien life .
Follow him on Twitter @ michaeldwall .
Follow us on Twitter @ Spacedotcom or Facebook .

Artist's depiction of the A-train constellation of Earth-observing satellites, with times the spacecraft are separated by when they fly.
NASA has voiced "substantial concerns" about a planned constellation of broadband satellites, saying the commercial spacecraft would increase the risk of collisions in an important slice of Earth orbit.
On Oct. 30, NASA submitted an official comment letter to the U.S. Federal Communications Commission (FCC) regarding a request by Texas-based company AST & Science to operate a network of up to 243 satellites about 450 miles (720 kilometers) above Earth's surface, as Ars Technica's Eric Berger reported last week .
This constellation, called SpaceMobile, will provide broadband service directly to cell phones, if all goes according to the company's plan. To pull this off, the SpaceMobile satellites will sport very large antennas — gear that covers an area of about 9,700 square feet (900 square meters), Berger wrote.
Space junk explained: The orbital debris threat (infographic)
The SpaceMobile satellites will therefore have quite big cross sections, boosting the probability of conjunctions, or close flybys, with other spacecraft in their neck of the orbital woods, states the NASA letter, which you can find here .
And the space agency cares quite a bit about that orbital region, because it houses the " A-Train ," a group of 10 Earth-observation missions operated by NASA, the U.S. Geological Survey and several international partners that travel around Earth in the same path. The A-Train's average altitude is 438 miles (705 km), but the satellites get as close to Earth as 429 miles (690 km) and as far away as 460 miles (740 km).
"Therefore, the AST constellation would be essentially collocated with the A-Train if the proposed orbit altitude is chosen," reads the comment letter, which was signed by Samantha Fonder, NASA representative to the Commercial Space Transportation Interagency Group.
NASA's calculations suggest that gliding safely among the SpaceMobile satellites might require 1,500 "mitigation actions," or spacecraft maneuvers, and 15,000 "planning activities" per year for the A-Train's handlers, Fonder wrote. That equates to about four maneuvers and 40 planning activities every day.
In addition, "this is an orbit regime that has a large debris object density (resulting from the Fengyun 1-C ASAT test and the Iridium 33-COSMOS 2251 collision) and therefore experiences frequent conjunctions with debris objects," the letter adds, referring, respectively, to a 2007 Chinese anti-satellite test and a 2009 smashup between one operational satellite and one dead one.
NASA would therefore like AST & Science to "consider alternative orbit regimes for this constellation, perhaps notably below the A-Train constellation, in order to allow for a more manageable safety-of-flight situation for a constellation of such large satellites," the letter reads.
AST & Science, for its part, maintains that SpaceMobile won't pose an undue collision risk. The company's calculations indicate that each of the network's satellites has just a 1-in-5,000 chance of colliding with another spacecraft at random, without any mitigation actions, over its operational life, Berger reported in another Ars Technica story last week . If AST & Science does get 243 satellites aloft, the probability of a random smashup constellation-wide would therefore be about 1 in 20.
AST & Science founder Abel Avellan also stressed that the company knows what it's doing, even though it has yet to launch any satellites to orbit. (The company is building a scaled-down prototype of a SpaceMobile spacecraft and plans to launch it in the second half of 2021, Avellan told Berger.)
"We're not a bunch of cowboys launching satellites," Avellan told Berger. "This is a serious, well-funded project."
Indeed, AST & Science recently snared about $128 million in a recent "Series B" investment round, Avellan told Berger, and the company's partners include Samsung, Rakuten and the Vodafone Group.
You can learn much more about SpaceMobile and NASA's objection to AST & Science's constellation plan in Berger's two stories, which you can find here and here .
SpaceMobile is not the only big broadband constellation in the offing, of course. Amazon aims to launch about 3,200 broadband satellites to low Earth orbit, and OneWeb has already lofted 74 internet satellites for a planned constellation of at least 648 spacecraft (though the company recently went through bankruptcy , potentially complicating those ambitions).
SpaceX has launched nearly 900 satellites for its Starlink megaconstellation and is already rolling out a public beta testing campaign for its broadband service. And there will be many more Starlink launches to come: Elon Musk's company already has FCC permission to operate 12,000 Starlink satellites in Earth orbit.
Starlink craft fly considerably lower than the A-train, zooming through space about 340 miles (550 km) above the planet's surface.