Media captionDr Geoff Evatt: "The vast, vast majority of objects to hit the Earth are really small"
A team of UK scientists has provided a new estimate for the amount of space rock falling to Earth each year.
It's in excess of 16,000kg. This is for meteorite material above 50g in mass.
It doesn't take account of the dust that's continuously settling on the planet, and of course just occasionally we'll be hit by a real whopper of an asteroid that will skew the numbers.
But the estimate is said to give a good sense of the general quantity of rocky debris raining down from space.
"The vast, vast majority of objects to hit the Earth are really small," explained Dr Geoff Evatt.
"We're talking about objects for which, when they strike the ground, the fragments sum together to over 50g. So, typically, 50g-10kg in total. Objects bigger than this are very, very infrequent," the University of Manchester mathematician told BBC News.
Image copyrightUNIVERSITY OF MANCHESTER/KATIE JOYImage captionBlack on white: Manchester scientist Romain Tartèse views a meteorite in Antarctica
One of the other outcomes of the study - produced in conjunction with colleagues from Cambridge University, Imperial College London, and the British Antarctic Survey - is that it enables a risk assessment to be made for the entire planet.
This reveals that the number of falls at the poles is about 60% of what you would expect at the equator.
It explains why you would absolutely want to put any long-term contingency facilities at higher latitudes.
The Global Seed Vault, for example, which aims to retain copies of Earth's plants in case of crisis, is sited at 78 degrees North on the Svalbard archipelago.
The new estimate, published in the journal Geology, grew out of the project to undertake the first UK-dedicated meteorite hunt in the Antarctic.
Image copyrightTHE CROP TRUSTImage captionThe contents of the global seed vault might be needed in the aftermath of a serious impact
Researchers involved in that effort wanted to be sure they would visit the most productive areas to perform such a quest.
The White Continent is the place on Earth where most meteorites have been recovered - with good reason: the "black on white" contrast of fallen space rocks on snow and ice makes searching a lot easier.
And hunters will typically go to places where the movement of the ice sheet concentrates the meteoritic material - so called stranding zones.
Dr Evatt and colleagues worked out how many objects ought to be in their chosen area - a place called the Outer Recovery Ice Fields, close to the Shackleton range of mountains in East Antarctica.
And they were virtually bang on with their expectation, finding close to 120 meteorites in two systematic searches over 2019 and 2020.
But having worked out a reliable flux for the number of falls at their chosen terrain, the scientists realised they could then use this knowledge to anchor a global assessment.
This incorporated orbital mechanics - how Earth's gravity will pull in nearby passing material - to work out how rates might vary by latitude. The model outputs a grand total of about 17,000 falls a year.
And this can be tested by looking at the data from fireball events. Satellites in orbit tracking the lightning in storms will also catch the blazing trail of a space rock plunging into the atmosphere.
"Satellites monitor these explosions in the sky, working out the energy of the events and also the longitude and latitude of where they happen. And from this you can see how they vary across the globe with latitude, and very nicely the curve you get from these fireballs fits with what we independently modelled using purely an applied mathematical approach," said Dr Evatt.
Prof Sara Russell leads the planetary materials group at the Natural History Museum in London. She wasn't involved in the research, but commented: "I think this is an amazing study, and this estimate sounds like it is in the right sort of ballpark.
"We think a total of about 40,000 tonnes (so 40,000,000 kg) of extra-terrestrial material falls to Earth each year, but the vast majority of this is in the form of tiny dust grains.
"This is a very difficult measurement to make with any accuracy and only about half a dozen meteorites are actually seen to fall each year, but of course almost all meteorite falls are not observed because they fall in the sea, in unpopulated areas or just no-one is looking!" she told BBC News.
Fireballs reported by US Government sensors (Apr 1988 to Mar 2020)
Image copyrightA.B.CHAMBERLIN(JPL-CALTECH)Image captionTotal impact energy is indicated by a circle's relative size and by a colour. The redder the colour, the higher the energy; the bluer the colour, the lower the energy
The Alaska village of Brevig Mission, the residents of which allowed a breakthrough in developing a vaccine for the Spanish flu of 1918. (Photo by Ned Rozell)
One hundred and two years ago, a strain of influenza virus spread across the globe, eventually reaching Brevig Mission in Alaska. Five days after the flu hit the Seward Peninsula, 72 of the 80 villagers in Brevig Mission were dead.
Through a series of events suited to a detective novel, researchers made a connection between Brevig Mission and the flu virus that helped prevent another outbreak of the 1918 flu, one of the worst epidemics ever experienced.
The 1918 flu, which infected 28 percent of people in the United States, killed 675,000 Americans. More than 20 million people died worldwide, most of them young adults.
Johan Hultin made it a personal mission to find a sample of the 1918 virus he calls “the most lethal organism in the history of man.”
A native of Sweden, Hultin was studying microbiology at the University of Iowa in 1949. There, he overheard a virologist say that the clue to understanding the 1918 flu might be found in the bodies of victims who were buried in permafrost.
Before he returned to Sweden, Hultin made a recreational trip up the Alaska Highway in 1949 with his wife. In Fairbanks, he met Otto Geist, the anthropologist whose work led to the founding of the University of Alaska Museum.
When Geist heard of Hultin's interest in the 1918 flu, he introduced Hultin to Lutheran missionaries who gave Hultin church records from Alaska villages in 1918. The records included detailed information on the dead, including where they were buried.
Hultin looked at an Alaska permafrost map and selected Brevig Mission as a place that met the requirements of massive flu mortality and frozen ground that might have preserved bodies.
After the sudden fatalities at Brevig Mission, officials of Alaska’s territorial government hired gold miners from Nome to dig a grave large enough for 72 bodies. Driving steam points into the permafrost on a rise near the village, the miners thawed a hole 12 feet wide, 25 feet long and six feet deep. The bodies buried there remained somewhat preserved by the frozen soil surrounding them.
Hultin flew to Brevig Mission in 1951. With permission from Native elders, Hultin, Geist and two Iowa researchers opened the mass grave, marked by two crosses.
Hoping to study the virus to see what had made it so deadly, Hultin's goal was the retrieval of live flu virus from the lungs of the victims. He removed lung tissue from four bodies, closed the grave, and returned to Iowa. In a lab there, he tried to revive the virus using a number of different methods. After he failed, Hultin resigned himself to perhaps never solving the mystery.
Fast-forward 46 years, to 1997. Hultin, then 72 and living in San Francisco, read an article in the journal Science written by a molecular pathologist, Jeffery Taubenberger. Taubenberger is chief of the viral pathogenesis and evolution section at the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland.
Taubenberger and his colleagues developed a method to isolate genetic material from viruses that he applied to the tissue of two young soldiers who died of the flu in 1918. He had access to autopsy specimens preserved since the Civil War.
The only drawback to Taubenberger's samples, encased in chunks of paraffin the size of a thumbnail, was that they were extremely small. He needed more to work with, but he did not know where to find tissue of people killed by the 1918 flu until Hultin wrote him.
Using $3,200 from his savings account, Hultin traveled to Brevig Mission in August 1997. After receiving permission from the elders, he again opened the mass grave.
At a depth of seven feet, he saw what he was looking for: a well-preserved body. The body was that of an obese woman. Her lungs, which Hultin removed, were well preserved. Hultin said the body's excess fatty tissue had insulated the lungs from decay during brief periods of permafrost thaw.
With the samples from the obese woman, in 2005 Taubenberger and his colleagues reconstructed the virus. They determined it had originated in birds and had mutated to infect people.
Using this information, researchers developed a vaccine and assured that the Spanish flu would never again infect anyone with access to modern medicine.
A cross marks a mass grave dug by miners for the bodies of 72 people who died at Brevig Mission in 1918. (Photo by Ned Rozell)
“The only sample we (found was) there because the elders of Brevig Mission let me go back into the grave again,” Hultin said in a 1998 interview over the phone from San Francisco. “They gave us the opportunity to do something good — not just for themselves but for the whole world.”
An update to last week’s column: Sea-ice scientist Melinda Webster, who was hoping to be headed to Svalbard right now and moving toward an eventual bunk aboard the research ship Polarstern frozen in the northern ice, has been delayed. She is waiting out travel restrictions due the COVID-19 virus that has affected everyone worldwide.
A native of Sweden, Hultin was studying microbiology at the University of Iowa in 1949. There, he overheard a virologist say that the clue to understanding the 1918 flu might be found in the bodies of victims who were buried in permafrost.
Before he returned to Sweden, Hultin made a recreational trip up the Alaska Highway in 1949 with his wife. In Fairbanks, he met Otto Geist, the anthropologist whose work led to the founding of the University of Alaska Museum.
When Geist heard of Hultin's interest in the 1918 flu, he introduced Hultin to Lutheran missionaries who gave Hultin church records from Alaska villages in 1918. The records included detailed information on the dead, including where they were buried.
Hultin looked at an Alaska permafrost map and selected Brevig Mission as a place that met the requirements of massive flu mortality and frozen ground that might have preserved bodies.
After the sudden fatalities at Brevig Mission, officials of Alaska’s territorial government hired gold miners from Nome to dig a grave large enough for 72 bodies. Driving steam points into the permafrost on a rise near the village, the miners thawed a hole 12 feet wide, 25 feet long and six feet deep. The bodies buried there remained somewhat preserved by the frozen soil surrounding them.
Hultin flew to Brevig Mission in 1951. With permission from Native elders, Hultin, Geist and two Iowa researchers opened the mass grave, marked by two crosses.
A native of Sweden, Hultin was studying microbiology at the University of Iowa in 1949. There, he overheard a virologist say that the clue to understanding the 1918 flu might be found in the bodies of victims who were buried in permafrost.
Before he returned to Sweden, Hultin made a recreational trip up the Alaska Highway in 1949 with his wife. In Fairbanks, he met Otto Geist, the anthropologist whose work led to the founding of the University of Alaska Museum.
When Geist heard of Hultin's interest in the 1918 flu, he introduced Hultin to Lutheran missionaries who gave Hultin church records from Alaska villages in 1918. The records included detailed information on the dead, including where they were buried.
Hultin looked at an Alaska permafrost map and selected Brevig Mission as a place that met the requirements of massive flu mortality and frozen ground that might have preserved bodies.
After the sudden fatalities at Brevig Mission, officials of Alaska’s territorial government hired gold miners from Nome to dig a grave large enough for 72 bodies. Driving steam points into the permafrost on a rise near the village, the miners thawed a hole 12 feet wide, 25 feet long and six feet deep. The bodies buried there remained somewhat preserved by the frozen soil surrounding them.
Hultin flew to Brevig Mission in 1951. With permission from Native elders, Hultin, Geist and two Iowa researchers opened the mass grave, marked by two crosses.
Hoping to study the virus to see what had made it so deadly, Hultin's goal was the retrieval of live flu virus from the lungs of the victims. He removed lung tissue from four bodies, closed the grave, and returned to Iowa. In a lab there, he tried to revive the virus using a number of different methods. After he failed, Hultin resigned himself to perhaps never solving the mystery.
Fast-forward 46 years, to 1997. Hultin, then 72 and living in San Francisco, read an article in the journal Science written by a molecular pathologist, Jeffery Taubenberger. Taubenberger is chief of the viral pathogenesis and evolution section at the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland.
Taubenberger and his colleagues developed a method to isolate genetic material from viruses that he applied to the tissue of two young soldiers who died of the flu in 1918. He had access to autopsy specimens preserved since the Civil War.
The only drawback to Taubenberger's samples, encased in chunks of paraffin the size of a thumbnail, was that they were extremely small. He needed more to work with, but he did not know where to find tissue of people killed by the 1918 flu until Hultin wrote him.
The inscription from a cross that marks the grave of 72 people, who died from the Spanish flu in Brevig Mission in 1918. (Photo by Ned Rozell)
Using $3,200 from his savings account, Hultin traveled to Brevig Mission in August 1997. After receiving permission from the elders, he again opened the mass grave.
At a depth of seven feet, he saw what he was looking for: a well-preserved body. The body was that of an obese woman. Her lungs, which Hultin removed, were well preserved. Hultin said the body's excess fatty tissue had insulated the lungs from decay during brief periods of permafrost thaw.
With the samples from the obese woman, in 2005 Taubenberger and his colleagues reconstructed the virus. They determined it had originated in birds and had mutated to infect people.
Using this information, researchers developed a vaccine and assured that the Spanish flu would never again infect anyone with access to modern medicine.
A cross marks a mass grave dug by miners for the bodies of 72 people who died at Brevig Mission in 1918. (Photo by Ned Rozell)
“The only sample we (found was) there because the elders of Brevig Mission let me go back into the grave again,” Hultin said in a 1998 interview over the phone from San Francisco. “They gave us the opportunity to do something good — not just for themselves but for the whole world.”
An update to last week’s column: Sea-ice scientist Melinda Webster, who was hoping to be headed to Svalbard right now and moving toward an eventual bunk aboard the research ship Polarstern frozen in the northern ice, has been delayed. She is waiting out travel restrictions due the COVID-19 virus that has affected everyone worldwide.
A Denver Post columnist says he was fired after disputing the idea that there are more than two sexes.
Jon Caldara, president of the libertarian Independence Institute, announced that he has been fired from the Post, chalking it up to "a difference in style" that his editors found "too insensitive."
"My column is not a soft voiced, sticky sweet NPR-styled piece which employs the language now mandated by the victim-centric, identity politics driven media," he said in a Facebook post."What seemed to be the last straw for my column was my insistence that there are only two sexes and my frustration that to be inclusive of the transgendered (even that word isn’t allowed) we must lose our right to free speech."
Caldara criticized an Associated Press directive saying that sex and gender are not binary. "There are only two sexes, identified by an XX or XY chromosome. That is the very definition of binary. The AP ruling it isn’t so doesn’t change science. It’s a premeditative attempt to change culture and policy. It’s activism," he wrote on Jan. 3. In a column two weeks later, Caldara also railed against a 2019 Colorado law that required elementary school children to be instructed in transgender ideology.
"Some parents weren’t thrilled a couple of years back when during school their little ones in Boulder Valley School District were treated to videos staring [sic] a transgender teddy bear teaching the kids how to misuse pronouns or when Colorado’s ‘Trans Community Choir' sang to kids about a transgender raven," Caldara wrote. "What are the protections for a parent who feels transgender singing groups and teddy bears with gender dysphoria might be ‘stigmatizing' for their kid?"
Caldara said that he was fired by the paper's editorial page editor, Megan Schrader, according to an interview with Westword published Monday.
"Megan told me I was the page's most-read columnist. But there's now a permanently and perpetually offended class, and in order to speak, you need to use their terminology. There's a whole lot of you-can't-say-that-ism going on right now."
In an email to the Washington Free Beacon, Schrader confirmed that she fired Caldara but declined to discuss the reason.
"I am writing a job description as we speak to fill his position," she said. "I hope that conservative Colorado writers will apply knowing that we value conservative voices on our pages and don't have a litmus test for their opinions."
Keep these in mind as you contemplate the direction of the American government over the past 50 years and especially since the Obama election.
The Goals of Communism
(as read into the congressional record January 10, 1963, from "The Naked Communist" by Cleon Skousen)
1. U.S. acceptance of coexistence as the only alternative to atomic war.
2. U.S. willingness to capitulate in preference to engaging in atomic war.
3. Develop the illusion that total disarmament of the United States would be a demonstration of moral strength.
4. Permit free trade between all nations regardless of Communist affiliation and regardless of whether or not items could be used for war.
5. Extension of long-term loans to Russia and Soviet satellites.
6. Provide American aid to all nations regardless of Communist domination.
7. Grant recognition of Red China. Admission of Red China to the U.N.
8. Set up East and West Germany as separate states in spite of Khrushchev's promise in 1955 to settle the German question by free elections under supervision of the U.N.
9. Prolong the conferences to ban atomic tests because the United States has agreed to suspend tests as long as negotiations are in progress.
10. Allow all Soviet satellites individual representation in the U.N.
11. Promote the U.N. as the only hope for mankind. If its charter is rewritten, demand that it be set up as a one-world government with its own independent armed forces. (Some Communist leaders believe the world can be taken over as easily by the U.N. as by Moscow. Sometimes these two centers compete with each other as they are now doing in the Congo.)
12. Resist any attempt to outlaw the Communist Party.
13. Do away with all loyalty oaths.
14. Continue giving Russia access to the U.S. Patent Office.
15. Capture one or both of the political parties in the United States.
16. Use technical decisions of the courts to weaken basic American institutions by claiming their activities violate civil rights.
17. Get control of the schools. Use them as transmission belts for socialism and current Communist propaganda. Soften the curriculum. Get control of teachers' associations. Put the party line in textbooks.
18. Gain control of all student newspapers.
19. Use student riots to foment public protests against programs or organizations which are under Communist attack.
20. Infiltrate the press. Get control of book-review assignments, editorial writing, policymaking positions.
21. Gain control of key positions in radio, TV, and motion pictures.
22. Continue discrediting American culture by degrading all forms of artistic expression. An American Communist cell was told to "eliminate all good sculpture from parks and buildings, substitute shapeless, awkward and meaningless forms."
23. Control art critics and directors of art museums. "Our plan is to promote ugliness, repulsive, meaningless art."
24. Eliminate all laws governing obscenity by calling them "censorship" and a violation of free speech and free press.
25. Break down cultural standards of morality by promoting pornography and obscenity in books, magazines, motion pictures, radio, and TV.
26. Present homosexuality, degeneracy and promiscuity as "normal, natural, healthy."
27. Infiltrate the churches and replace revealed religion with "social" religion. Discredit the Bible and emphasize the need for intellectual maturity which does not need a "religious crutch."
28. Eliminate prayer or any phase of religious expression in the schools on the ground that it violates the principle of "separation of church and state."
29. Discredit the American Constitution by calling it inadequate, old-fashioned, out of step with modern needs, a hindrance to cooperation between nations on a worldwide basis.
30. Discredit the American Founding Fathers. Present them as selfish aristocrats who had no concern for the "common man."
31. Belittle all forms of American culture and discourage the teaching of American history on the ground that it was only a minor part of the "big picture." Give more emphasis to Russian history since the Communists took over.
32. Support any socialist movement to give centralized control over any part of the culture--education, social agencies, welfare programs, mental health clinics, etc.
33. Eliminate all laws or procedures which interfere with the operation of the Communist apparatus.
34. Eliminate the House Committee on Un-American Activities.
35. Discredit and eventually dismantle the FBI.
36. Infiltrate and gain control of more unions.
37. Infiltrate and gain control of big business.
38. Transfer some of the powers of arrest from the police to social agencies. Treat all behavioral problems as psychiatric disorders which no one but psychiatrists can understand.
39. Dominate the psychiatric profession and use mental health laws as a means of gaining coercive control over those who oppose Communist goals.
40. Discredit the family as an institution. Encourage promiscuity and easy divorce.
41. Emphasize the need to raise children away from the negative influence of parents. Attribute prejudices, mental blocks and retarding of children to suppressive influence of parents.
42. Create the impression that violence and insurrection are legitimate aspects of the American tradition; that students and special-interest groups should rise up and use united force to solve economic, political or social problems.
43. Overthrow all colonial governments before native populations are ready for self-government.
44. Internationalize the Panama Canal.
45. Repeal the Connally reservation so the United States cannot prevent the World Court from seizing jurisdiction over nations and individuals alike.