Friday, July 26, 2013

A Russian Meteor, Ancient Craters, and Coming Events

New imaging technologies help scientists study meteors and see what's been hidden under farmland in Iowa.
  1. Analyzing the Chelyabinsk Meteorite
  2. Iowa Craters
  3. Earth's Top 10 Known Impact Sites
The 'pure science' angle of this news fascinates me, but we've recently discovered a grimly practical application of astronomy.

A Bad Day for Dinosaurs

Now and then a rock several miles across hits Earth. That happened near what's now the Yucatan peninsula about 65,000,000 years back.

(Image © Don Davis; from PAINTINGS at

Dinosaurs might have survived the Chicxulub impact: if there hadn't been another near-simultaneous asteroid strike, and massive volcanic eruptions.

There's an odd circular feature near the vulcanism, so there might have been three impacts that time. Earth can be a rough neighborhood.

Technology, Ethics, and Asteroids

We (probably) have plenty of time to get ready for the next 'K-T event.' But since cleaning up after even a small rock's demise is a big job, I think being prepared for incoming mountains is prudent.

Provided that legal issues don't get in the way, we'll probably have the technology to move asteroids into safe orbits in several years. Quite a few of those rocks are rich in iron and nickle, so funding shouldn't be a problem in the long run. Asteroid mining could be an important industry in a few decades.

I don't see a problem with changing an asteroid's orbit, by itself. Using science and technology are part of being human. How we use these tools involves ethics, and I've been over that before. (Catechism of the Catholic Church, 2292-2295)

As for whether or not it's right to keep an asteroid from hitting Earth, I'll say what I've said before. We're called to holiness, not stupidity.

Asteroids, Spaceships, and a Little History

Two hundred years ago, folks knew about asteroids. A monk named Guiseppe Piazzi discovered the first one, Ceres, in 1801.

Over the next few years astronomers found 2 Pallas, 3 Juno, and 4 Vesta. A few years later they hadn't found any more of these 'minor planets,' and most decided that they could stop looking. Karl Ludwig Hencke didn't agree, and eventually spotted 5 Astraea.

One hundred years back, in 1908, something exploded over Podkamennaya Tunguska River.

Around that time the zeppelin was the latest thing in transportation technology, astronomers were using long-exposure photographic plates to find asteroids, and Konstantin Tsiolkovsky had shown how rockets could carry us to other planets.

Today, robot spaceships are exploring the Solar system, and the White-Juday warp field interferometer may show that Alcubierre's math is a good match with reality:

The Sicilian Connection

Guiseppe Piazzi was born in Valencia, died in Naples, and got a grant from the Viceroy of Sicily to build an observatory there.

Oddly enough, Guiseppe Piazzi wasn't looking for a new planet. Baron Franz Xaver von Zach had 24 other astronomers organized for planet-hunting, and that's another topic.

1. Analyzing the Chelyabinsk Meteorite

(Ural Federal University/V Gorkhovsky)
"Often referred to as the Chebarkul meteorite after the lake where many pieces were found, the space rock appears to be a standard 'chondrite' "
"Russian Chelyabinsk meteorite pieces go under microscope"
BBC News (July 12, 2013)

"Scientists have released microscopic images of fragments of the meteorite that hit central Russia in February.

"A team from the Ural Federal University was able to analyse some of the dozens of samples as soon as they were found.

"But the technique they used allowed them to assess the rock's chemical make-up at the microscopic level even as they snapped pictures of the fragments.

"This will provide extra information on the space rock's formation and journey.

"The fragments represent just a small portion of the remains of the 17m-diameter body that struck the Earth's atmosphere in a spectacular trail of light over the city of Chelyabinsk...."
The meteorite blew in windows and knocked a hole in at least one building when it exploded over Russia this February. I still haven't heard of anyone being killed in that incident, for which I'm duly grateful.

(Reuters//Yevgeni Yemeldinov, used w/o permission)
"Workers repair damage caused after a meteorite passed above the Urals city of Chelyabinsk February 15, 2013." (Reuters)

Rocks, Language, and Reporters

"...The team, led by Urals Federal University's Viktor Grokhovsky, determined right away that the overall chemistry of the meteorite was a familiar 'chondrite'.

" 'The fragments contain a standard number of minerals, including olivine, pyroxene, troilite and kamacite. These minerals that can be discovered only in outer space confirm the fragments' extraterrestrial nature,' he told the Voice of Russia at the time...."
(BBC News)
Maybe there's a problem with the translation here:
"...olivine, pyroxene, troilite and kamacite. These minerals that can be discovered only in outer space...."
The statement, as reported, isn't quite true. The mix of minerals may be distinctly extraterrestrial, but some of stuff, like olivine and pyroxene, is fairly common on Earth.

For example, folks have known about the iron - magnesium silicates we call olivines for thousands of years.

Peridot, an olivine, was a popular semiprecious gemstone back when Egypt had one of the world's leading civilizations: and no, ancient Egyptians did not come from outer space, which is another topic or two.

We've found olivine on Mars, too: so the mineral does 'come from outer space.' Sometimes.

Aztec rulers used quite a bit of jade, which is a pyroxene. Again, this mineral is found on Earth and Mars. Sodium calcium magnesium iron aluminum silicates aren't as common as dirt on this planet, but they're often part of igneous and metamorphic rocks.

Triolite shows up in rocks that come from Earth, but it's rather rare here. It's more likely to be in meteorites that come from our moon, or Mars: so if a rock that's lying around on the surface of Earth has triolite, the odds are pretty good that it came from somewhere else.

Kamacite is a iron-nickel alloy that shows up in meteorites: so that part of Grokhovsky's statement is accurate.

My guess is that Viktor Grokhovsky knows that olivines and pyroxene are native to Earth. We're probably looking at an accurate statement that was translated: and then filtered through two sets of journalists. Small wonder that it got a trifle garbled.

Old Rock, New Knowledge

(Ural Federal University/V Gorkhovsky)
"The X-ray maps show the precise distribution of individual chemical elements"
"...Simon Burgess of Oxford Instruments, which made the X-max silicon drift detector used by the team. "For the researchers who are looking at this meteorite, it's going to be telling them information about which (mineral) phase is associated with which," he [Oxford Instruments' Simon Burgess] told BBC News.

" 'When they get into more detail beyond what the main chemistry of the meteorite is, they may be looking at processes in terms of how it formed, the temperature it formed at, what its history has been since its formation, possibly things about what happened to it during its impact with the Earth.

" 'A lot of that you cannot tell just by crushing it up and getting a "bulk analysis"; you have to look at the chemistry of the individual parts and associations between the different minerals in the meteorite.'..."
(BBC News)
The Chebarkul meteorite may be as old as Earth. By studying it we may learn more about the very early days of the Solar system.

That's nice from the 'pure science' point of view: and could help us learn how and where to look for more falling rocks.

2. Iowa Craters

We call the place Iowa, recalling the Ioway or Báxoje who lived there for quite a while: that's different names for the same folks.

Spain's rulers said they owned the territory for a while, the French called it La Louisiane, New France in English, before handing it back to Spain, and losing a war. Then  France got liberated by folks who didn't like kings.

After several years of idealism and wholesale executions, a Corsican general named Bonaparte collected what remained of France, retrieved La Louisiane, and sold it to the United States.

The folks who actually lived there hadn't been consulted during those deals, and sided with the English when the United States bought the territory. I can't say that I blame them, and that's another topic.

Long before any of that happened, the real estate we call Iowa was occupied by corals, hadrosaurs, plesiosaurs, and mastodons: not all at the same time, of course.

Now and then something big fell out of the sky, which gets me back on-topic.

Decorah Impact Structure

(Created using ESRI's ArcScene; by Adam Kiel, Northeast Iowa RC&D; via USGS, Livescience; used w/o permission.)
"A three-dimensional view of Decorah, Iowa, and the Upper Iowa River with the location of the Decorah Impact Structure marked with the white dotted line. Scene is looking due north...."
"Meteorite Crater Under Iowa Confirmed in New Images"
Andrea Thompson, OurAmazingPlanet Managing Editor, LiveScience (March 6, 2013)

"Buried beneath the rocks, dirt, buildings and roads of the city of Decorah, Iowa, lies a 470 million-year-old meteorite crater.

"Unlike the craters on the pockmarked surfaces of the moon and Mars, this crater can't be seen by looking down at Earth's surface, at least not by the human eye.

"But recent aerial surveys primarily aimed at getting a better picture of the minerals that underlie the region got a look at the crater structure using instruments that detect the variations in gravity of different types of rock, as well as their ability to conduct electricity...."
Quite a bit changes in 470,000,000 years. Continental drift recycles ocean floors while rearranging land masses. Iowa has been flooded and drained a few times, alternately collecting sediments and getting them eroded into a new landscape.

Phrases like 'ancient as the hills' are meaningful in a poetic sense. Compared to a human lifespan, a hill seems permanent. I think the metaphor is still valid, even if we've long since learned that landscapes change.

Ancient Crater, Today's Mineral Resources

"Iowa Meteorite Crater Confirmed"
USGS press release (March 5, 2013)
"USGS Airborne Surveys Back Up Previous Decorah Research

"Recent airborne geophysical surveys near Decorah, Iowa are providing an unprecedented look at a 470-million-year-old meteorite crater concealed beneath bedrock and sediments.

"The aerial surveys, a collaboration of the U.S. Geological Survey with the Iowa and Minnesota Geological Surveys, were conducted in the last 60 days to map geologic structures and assess the mineral and water resources of the region.

" 'Capturing images of an ancient meteorite impact was a huge bonus,' said Dr. Paul Bedrosian, a USGS geophysicist in Denver who is leading the effort to model the recently acquired geophysical data. 'These findings highlight the range of applications that these geophysical methods can address.'

"In 2008-09, geologists from the Iowa Department of Natural Resources' (Iowa DNR) Iowa Geological and Water Survey hypothesized what has become known as the Decorah Impact Structure. The scientists examined water well drill-cuttings and recognized a unique shale unit preserved only beneath and near the city of Decorah. The extent of the shale, which was deposited after the impact by an ancient seaway, defines a 'nice circular basin' of 5.5 km width, according to Robert McKay, a geologist at the Iowa Geological Survey.

"Bevan French, a scientist the Smithsonian's National Museum of Natural History, subsequently identified shocked quartz - considered strong evidence of an extra-terrestrial impact - in samples of sub-shale breccia from within the crater....

"...The Iowa and Minnesota airborne geophysical surveys are targeting an igneous intrusion, known as the Northeast Iowa Igneous Intrusive complex, that may be similar to the Duluth layered igneous complex exposed in the Lake Superior region of northern Minnesota. Known copper, nickel, and platinum group metal resources were deposited during the formation of the Duluth complex. Both of these complexes are associated with a large structural feature known as the Midcontinent Rift, which is exposed in the Lake Superior Region but is covered by younger rocks as it extends to the south through Iowa, Nebraska, Kansas, and Missouri.

"This geophysical survey is part of a larger USGS effort to evaluate the concealed mineral resource potential of the greater Midcontinent Rift region that formed about 1.1 billion years ago."
About "the concealed mineral resource potential:" I'm not bothered by the idea that humans use natural resources. It's our job:

Manson Impact Structure

(Adapted from Iowa Geology 1999, Iowa Department of Natural Resources, via Iowa Department of Natural Resources, used w/o permission.)
"Cross-section view of the geologic features of the Manson Impact Structure."
"Iowa's Manson Impact Structure"
Raymond R. Anderson, Iowa Department of Natural Resources
Adapted from Iowa Geology 1999, Iowa Department of Natural Resources

"Seventy-four million years ago, near the end of the Cretaceous Period, central Iowa lay near the shoreline of an inland seaway that separated eastern North America from rapidly rising mountains to the west. The low-lying Iowa landscape was home to a rich and varied population of plants and animals, including dinosaurs and small mammals. These organisms lived in a fern-rich, mixed conifer and deciduous forest with a warm, moist climate much like today’s Gulf Coast. The environment dramatically changed when a stony meteorite, over one mile in diameter, weighing about 10 billion tons and traveling about 45,000 miles per hour, blasted through the atmosphere and crashed to earth.

"In the fraction of a second that it took the meteorite to penetrate about one mile into the ground, the shock wave created by the initial contact with the surface reached the back side of the meteorite and its potential energy was transformed to kinetic energy, the equivalent of about 10 trillion tons of TNT. An electromagnetic pulse moved away from the point of impact at nearly the speed of light, and instantly ignited anything that would burn within approximately 130 miles of the impact (most of Iowa). The shock wave toppled trees up to 300 miles away (Chicago, Minneapolis, and St. Louis), and probably killed most animals within about 650 miles (Detroit and Denver). The blast left a crater over 24 miles in diameter centered in an area of unimaginable death and destruction.

"Today there is no land surface expression of the crater that exists 100 to 300 feet below the town of Manson (Calhoun County), which lies near the center of the crater that bears its name...."
Decorah's 470,000,000 year old crater isn't the only one in Iowa. More recently, while the Rocky Mountains were under construction, Iowa had oceanfront property. It was a good time to be a dinosaur.

(Karen Carr, via "TheFernleaf" and Iowa Geological and Water Survey, used w/o permission)
" 'Dinosaur Society Hadrosaur,' by natural history and wildlife artist Karen Carr, courtesy of 'TheFernleaf'  "

Then, about 74,000,000 years ago, a mile-wide rock hit Earth. Going from 45,000 miles an hour to a full stop released around 10,000,000 megatons of energy: rather abruptly.

I'd just as soon not find out what a blast like that would do to our emerging global civilization.

The 'Manson impact' wasn't the big one for dinosaurs, by the way. That happened about 9,000,000 years later and a few thousand miles farther south.

3. Earth's Top 10 Known Impact Sites

(Detlev van Ravenswaay, Science Source, via National Geographic News, used w/o permission)
"An illustration of the Chicxulub impact crater in the Yucatán Peninsula."
"Asteroid Impacts: 10 Biggest Known Hits"
Brett Line, National Geographic News (February 14, 2013)
"The asteroid 2012 DA14 will miss Earth on Friday, but there's a long history of hits.

"There's one physical connection that isn't going down after Valentine's Day this year: Earth and asteroid.

"The asteroid known as 2012 DA14 will narrowly miss Earth this Friday, the closest asteroid flyby on record. But the planet has not always been so lucky.

"Earth's craters are enduring testaments to direct asteroid hits. And though millions-in some cases billions-of years of erosion have made it difficult to determine the exact size of the meteorites, there is a general scientific consensus around the world's largest craters, which mark the largest asteroid impacts...."
Four of the top 10 craters listed came from impacts in the last 100,000,000 years: a pair from around  67,000,000 years ago, and another roughly 35,250,000 years back.

Granted, we had something like a 5,300,000 year gap between the earlier set, and 700,000 years between the most recent. This 'top 10' list doesn't include smaller craters like the ones in Iowa, so if there is an 'asteroid season' on Earth it probably wouldn't show up in this set of data.
  • Vredefort Crater
    Free State, South Africa
    • 2,000,000,000 years b.p.
  • Sudbury Basin
    Ontario, Canada
    • 1,800,000,000 years b.p.
  • Acraman Crater
    South Australia, Australia
    • 580,000,000 years b.p.
  • Woodleigh Crater
    Australia, Australia
    • 364,000,000 years b.p.
  • Manicouagan Crater
    Quebec, Canada
    • 215,000,000 years b.p.
  • Morokweng Crater
    North West, South Africa
    • 145,000,000 years b.p.
  • Kara Crater
    Nenetsia, Russia
    • 70,300,000 years b.p.
  • Chicxulub Crater
    Yucatán, Mexico
    • 65,000,000 years b.p.
  • Popigai Crater
    Siberia, Russia
    • 35,700,000 years b.p.
  • Chesapeake Bay Crater
    Virginia, United States
    • 35,000,000 years b.p.

Falling Rocks

We live in a 'falling rocks' zone. Every day about 100 tons of sand and gravel become meteors.

Most of this cosmic debris is so small that we never notice it. Some makes a vapor trail bright enough to inspire 'wishing on a shooting star' folklore.

Every century or so, something like Kamensk-Uralsky's recent light show or the Tunguska event happens.

(Reuters/Amateur video via Reuters TV, used w/o permission)
"Trail of a meteorite crossing the early morning sky above the city of Kamensk-Uralsky February 15, 2013, is seen in this still image taken from video footage from a dashboard journey recorder...." (Reuters)

Kilometer-wide rocks fall out of the sky every few hundred thousand years. Bigger ones hit less frequently, so we probably won't have another 'Chesapeake Bay' impact for a million years.

On the other hand, those are average intervals. Asteroid collisions don't seem to happen on a schedule. We may have ten million years before the next 'big one.' Or we may have ten years.

I'm not worried, anxious, about falling rocks. I am, however, concerned, interested because I live on a planet that occasionally gets in the way of asteroids.

Now that we know about asteroid impacts, and are developing the necessary technology, I think we should start preparing for the next incoming mountain.

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What's That Doing in a Nice Catholic Blog?

From time to time, a service that I use will display links to - odd - services and retailers.

I block a few of the more obvious dubious advertisers.

For example: psychic anything, numerology, mediums, and related practices are on the no-no list for Catholics. It has to do with the Church's stand on divination. I try to block those ads.

Sometime regrettable advertisements get through, anyway.

Bottom line? What that service displays reflects the local culture's norms, - not Catholic teaching.