Tag Archives: meteorite

Cassini sees meteoroids pummeling Saturn’s rings

Posted on by
Reply

Larry Beck was watching TV last Friday night when he heard a loud crash on his roof. Beck thought something that had fallen off a plane since his home is in the flight path of a nearby airport. When he went into the attic to look, he discovered a hole in his roof and a softball-sized rock, which was soon confirmed as a meteorite. Credit: NBCConnecticut.com

The spectacular fireball over Chelyabinsk, Russia in February and a more recent meteorite fall through the roof of a home in Wolcott, Connecticut last Friday remind us the solar system is still littered with debris left over from its formation 4.6 billion years ago.

Piles of small meteorites dropped by the Chelyabinsk fireball on Feb. 15, 2013 and collected by meteorite hunter Mike Farmer. Credit: Mike Farmer

During and immediately after the formation of the planets, meteorite bombardment was nonstop. Since then the impact rate has dropped dramatically – a good thing for life – but continues to this day as a steady rain of everything from fine dust to the occasional teeth-rattling meteorite strike.

Five images of Saturn’s rings, taken by NASA’s Cassini spacecraft between 2009 and 2012, show clouds of material ejected from impacts of small objects into the rings. Click for large version. Credit: NASA/JPL-Caltech/Space Science Institute/Cornell

Besides Earth, amateur and professional astronomers have recorded meteorite or comet strikes on the moon and Jupiter. Now we can add Saturn to the list. Detailed study of thousands of images sent back to Earth by the Cassini spacecraft have turned up nine meteoroid strikes on Saturn’s rings in 2005, 2009 and 2012.

Think of the rings as a giant meteoroid detector/collector. If Earth gathers some 37,000-78,000 tons of space debris per year (mostly as dust but approx. 3-8 tons as rocks weighing 1/3 ounce to 2.2 lbs.), Saturn’s rings, with a surface area 100 times that of our planet, is more like humpback whale during feeding season.

This illustration shows the shearing of an initially circular cloud of debris as a result of the particles in the cloud having differing orbital speeds around Saturn. The numbers in the lower left of the panels in the still image show how quickly a cloud can be elongated as it orbits the planet. Credit: NASA/Cornell

Meteoroids pummeling the rings range in size from about a half-inch to several yards (one cm to several meters). When they bash into the icy ring particles they self-destruct, creating clouds of dust and ice in the process. The material is then sorted according to its distance from the planet – closer debris orbits more quickly, material further out more slowly. Soon the dust cloud gets stretched into an elongated bright streak that Cassini can photograph as it looks down (or up) onto the ring plane.

Detail of a debris cloud from a meteoroid strike in Saturn’s C-ring in 2012. Credit: NASA/JPL-Caltech/Space Science Institute/Cornell

“These new results imply the current-day impact rates for small particles at Saturn are about the same as those at Earth — two very different neighborhoods in our solar system — and this is exciting to see,” said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

It’s fascinating to realize that the sight of a meteor in Earth’s starry skies finds its counterpart among the icy boulders of Saturn’s rings nearly a billion miles afield.

 

Meteorites may have spiked primordial soup with energy essence

Posted on by
2

The early Earth received mineral and chemical contributions from other solar system objects including meteorites, comets and cosmic dust. Interactions between them created the complex molecules that were life’s precursors. Credit: Mary P. Hrybyk-Keith / NASA

One of the great unanswered questions is how did life arise. Since so many of life’s functions involve chemical interactions on a microscopic scale, it’s a good guess that chemistry was involved from the beginning. No one knows exactly how, but nature left an open door for the inanimate to become animate.

Likely that door is closed now on planet Earth; any living form that might spontaneously arise through chemistry today would probably be eaten by the hordes of animate beings whose ancestors took charge long ago.

Meteorite bombardment was especially intense about 3.9 billion years ago on Earth, shown here with the moon, which was much closer then. Life formed right around this time. Phosphorus from meteorites may have gone into building a relative of ATP, the chemical that powers all living things. Credit: D. Aguilar

In a bit of research that sheds light on how life’s precursor chemicals formed, a team of scientists at the University of Leeds in England examined how meteorites may have contributed one of the key elements that allowed life to literally “power up” – phosphorus.

Meteorite phosphorus is very reactive, meaning it likes to combine with other elements and molecules to form a variety of compounds.

We touched on phosphorus last month after Curiosity discovered the element in an ancient stream bed on Mars. It’s a key ingredient in the hereditary molecule DNA shared by virtually all living organisms and ATP (adenosine triphosphate), a chemical used to store and transport energy in cells.

Looking like needles and worms, schreibersite reflects from the polished surface of a Canyon Diablo meteorite. Photo: Bob King

DNA is to heredity what ATP is to staying alive. All life on Earth is powered by ATP. Meteorites contain phosphorus in a metallic material called schreibersite, made of iron, nickel and phosphorus. Slice open an iron meteorite and you’re likely to see silvery stripes of schreibersite gleaming back.

Researchers took samples of the Russian iron meteorite Sikhote-Alin that crashed to Earth in 1947 and allowed them to stew in acid taken from the Hveradalur geothermal area in Iceland. The idea here was to simulate conditions on the early, volcanically-active Earth when the number of meteorites raining down on the planet was far greater than what it is today.

The rock was left to react with the acidic fluid in test tubes incubated by the surrounding hot spring for four days, followed by a further 30 days at room temperature. When the homemade “primordial soup” was analyzed, the scientists found pyrophosphite, a cousin molecule of pyrophosphate – the part of ATP responsible for energy transfer.

Scientists think that pyrophosphite may have served as the power sources for what they call “chemical life”, not-quite-alive materials that act in some ways like living things:

The Curiosity rover found phosphorus, among other essential ingredients for life, when it drilled into the Sheepbed rock layer on Mars. Credit: NASA/JPL-Caltech

“Chemical life would have been the intermediary step between inorganic rock and the very first living biological cell. You could think of chemical life as a machine – a robot, for example, is capable of moving and reacting to surroundings, but it is not alive. With the aid of these primitive batteries, chemicals became organized in such a way as to be capable of more complex behaviour and would have eventually developed into the living biological structures we see today,” said Dr Terry Kee, lead researcher from the University’s School of Chemistry.

The group now plans to build a ‘geological fuel cell’ using minerals and gases common on the early Earth, subject them to different chemicals and see what new chemicals result.

This artist’s conception shows a young, hypothetical planet around a cool star. A soupy mix of potentially life-forming chemicals can be seen pooling around the base of the jagged rocks. Credit: NASAJPL-CaltechT.-Pyle-SSC

The more we seek the origin of this wonderful thing called life, the more our journey takes us into contributions from outer space. Whether it’s phosphorus from meteorites or water and carbon compounds delivered by comet bombardment, our little planet served as a mixing bowl for a recipe called life.

Article source: Univ. of Leeds

Hello world, meet the new Chelyabinsk meteorite

Posted on by
13

A trove of Chelyabinsk meteorites collected or purchased by Arizona meteorite hunter Michael Farmer. Many are rounded as their outer skins were melted during flight through the atmosphere. Credit: Michael Farmer

It’s official. February’s Russian fireball finally has a birth certificate with a name. The Meteoritical Society, the organization responsible for naming and maintaining the official tally of meteorite finds and falls, has named it Chelyabinsk (pronounced chel-YAH-binsk) after the largest city in the region of the fall.

Meteorite hunter Evgenij Suhanov smiles as he holds a fresh specimen found in the countryside near Chelyabinsk. Credit: Evgenij Suhanov

According to the rules of the Society’s Nomenclature Committee, acceptable names for meteorites include terrain-based features like rivers, mountains, lakes, bays, capes, and islands; political features such as towns, counties, states, and provinces, and sites of human activity such as parks, mines, historical sites and railroad stations. Sites connected to recent human activity like buildings, shops and businesses, schools, bridges, roads, and golf courses are generally not acceptable. Sorry, there won’t be a Target meteorite anytime soon.

A beautiful Chelyabinsk “button” showing flight orientation. The left photo shows the nosecone side that sped downward through the atmosphere. The back side has a melted, frothy texture. Credit: Evgenij Suhanov

Official names are required to publish studies about this or that meteorite in some scientific journals. A meteorite gets a name after it’s been analyzed and classified in the lab. Until that time it’s one of a multitude of “unclassified” meteorites with no official status.

95.6% of meteorites found or seen to fall like Chelyabinsk are classed as ordinary chondrites, rocks containing rounded mineral grains called chondrules and peppered with flakes of metallic iron-nickel. Chondrites (KON-drites) derive from the outer crust of their parent asteroids and get a free trip to Earth after being blasted loose from long-ago impacts by other asteroids.

Ordinary chondrites are further subdivided into H, L and LL varieties. H stands for high metal (12-21% iron-nickel metal in the rock), L for low metal (5-10%) and LL (about 2%).

Chondrules and iron-nickel metal grains on a sawn face of an unnamed chondrite from northern Chile. It’s probably an H5 – high metal and altered minerals from heating. Credit: Randy Korotov

Rocks that ultimately came to Earth as meteorites were heated to varying degrees by the decay of radioactive elements in the asteroid’s crust altering their mineral structure. Those least affected by heat and which most resemble the first solid materials to form in the solar system are petrographic type 3; those most affected are type 6. So for example, an L3 meteorite has low metal and was little affected by heating, while an H6 has lots of metal and got baked.

A cut-open Chelyabinsk specimen shows a light texture with darker patches of shocked or impact-melted minerals. When meteorite minerals like olivine are shocked by impact, chemical changes occur that make them darken. Credit: Evgenij Suhanov

I apologize for the “tech talk” but it will help us better understand the nature of the Russian meteorite. Chelyabinsk is classified as an LL5 chondrite – low metal and a good amount of mineral alteration from early heating. Further, about a third of the stones found consist of a dark impact melt containing mineral and chondrule fragments. Like the name suggests, the melted rock probably came from the impact that sent chunks of the original asteroid on their earthward course.

You might wonder how long it took for the Chelyabinsk meteoroid (the name given a meteor or meteorite before it enters Earth’s atmosphere). Called its cosmic ray exposure age, the average time for an LL5 chondrite to arrive after getting blown off its asteroid is around 31 million years. That is a long, long time yet only a fraction – about 0.7% – of the meteorite’s true age of 4.6 billion years. Kind of makes you stop and reflect, doesn’t it?

Early samples from the perimeter of the hole in the ice of Lake Chebarkul. Credit:  AP / The Urals Federal University Press Service, Alexander Khlopotov

I’ve been checking Chelyabinsk meteorites for sale on eBay and the few private sales I’ve been aware of. Prices range from around $35-150 per gram. As of March 21 there are 115 meteorites advertised on eBay as Chelyabinsk by everyone from first-time sellers to well-established meteorite folks. Surprisingly, most of the specimens appear to be the real thing. Chelyabinsk meteorites have either black or brown fusion crust – the dark, melted outer crust from heating during atmospheric entry -  smooth or bumpy surfaces and are generally small. Undoubtedly the force of the explosion when the meteorite came down shattered the original meteoroid to bits.

Another fine fusion-crusted Chelyabinsk meteorite, this one weighing 43 grams. Credit: Evgenij Suhanov

Only a few larger pieces have been recovered. The largest weighs about 4 lbs. (1.8 kg). The total amount of material collected by locals and scientists is at least 220 lbs (100 kg) and perhaps more than 1,100 lbs. (500 kg). As for that 26 foot (8 m) hole in the ice in Lake Chebarkul likely punched out by a falling space rock, divers have yet to retrieve the culprit. They did however just discover a 10-foot (3 m) underwater crater offset about 32 feet from the hole.

For more details on the Chelyabinsk meteorite, click HERE.

Update on the fireball that exploded over Russia

Posted on by
3

The largest ~ 1 kilogram (2.2 lbs) Chelyabinsk / Chebarkul meteorite found to date alongside many smaller fragments. Credit: Screenshot from video, courtesy press-service Ural Federal University

The sun rose twice over the Ural Mountains in Russia Friday February 15. No one expected the second sun, a meteoroid that slammed into the atmosphere so fast it set the air aglow with a fire even brighter than the real sun. It lasted more than 30 seconds before exploding and sending a shock wave rippling across the city of Chelyabinsk and surrounding countryside.

Thousands of residents of small towns in the area of the fall at and around Lake Chebarkul have been busy hunting for meteorite fragments by looking for holes in the snow cover and then carefully clearing away the white stuff until a little black rock remains. It must sound and look like an Easter egg hunt out there. Some of the locals are cashing in on meteorite fever by offering rides to the big hole in the ice on Chebarkul Lake thought to have been punctured by a meteorite fragment.

Another view of the biggest meteorite fragment. It’s shows regmaglypts or dimples created when high temperatures during entry heat and melt away minerals on the surface. Click to see more images of  meteorites found from the fall. Credit: Screenshot from video, courtesy press-service Ural Federal University

Many of the stones – some real, some obviously fake – are popping up on various auction sites in Russia and elsewhere. A quick check on eBay under “Chelyabinsk meteorite” turned up 29 listings today. How many of those are real? Hard to say.

One meteorite hunter interviewed by a BBC team put it this way: “It’s like hunting or fishing. When you see an animal, your heart starts to beat fast, and when you’re fishing – it’s like pulling the fishing rod and thinking there’s something extraordinary. This is the same – you see a tiny hole, try it, and here it is.”

After more than a week of study, we know a little more about the asteroid that created this shower of stones in large part from information recorded by a network of infrasound sensors operated by the Comprehensive Test Ban Treaty Organization (CTBTO). Their purpose is to monitor nuclear explosions.

https://www.youtube.com/watch?v=H-8ij80vs1E
Recording of infrasound from the Russian fireball that’s been sped up 135 times so we can hear it. The original file was 25 minutes long!

Infrasound, a very low frequency sound wave that can travel long distances, can only be heard by a few animals including elephants. When a large meteor enters the atmosphere it sends ripples of infrasound across the atmosphere around the planet revealing information about its speed, direction of travel and how much energy it contains.

“The Russian meteor’s infrasound signal was was the strongest ever detected by the CTBTO network. The furthest station to record the sub-audible sound was 9,300 miles away in Antarctica,” according to a NASA press release.

Russian fireball on Feb. 15, 2013 recorded by a dashcam

Here’s what we know based on an analysis by Western Ontario Professor of Physics Peter Brown:

* Size: 56 feet (17 meters) in diameter
* Weight: 11,000 tons (10,000 metric tons)
* Speed: 40,000 mph (64,000 km/hour) and broke apart 12-15 miles above Earth’s surface
* Exploded with the power of 470 kilotons of TNT which is equal to more than 23 1940s-era atomic bombs

We looked at the asteroid’s orbit the other day and discovered it belonged to the Apollo family of Earth-crossing asteroids. When farthest from Earth it used to mingle with its many friends in the asteroid belt. Like the majority of asteroids between Mars and Jupiter it has a rocky composition.

Digging for “Chebarkul” meteorites in the snow, new pix plus an orbit

Posted on by
2

“Chebarkul” meteorite fragment with black fusion crust, pale crystalline interior and black, glassy shock veins caused by the impact that liberated the meteorite from its home asteroid millions of years ago. Click to enlarge. Credit: Laboratory of Meteoritics, Vernadsky Institute

We’ve seen the first fragments of meteorites from last Friday’s Russian fireball. I thought you’d also like a look at more recent, high-quality close-ups of larger pieces.  All these images are from the Laboratory of Meteoritics at the Vernadsky Institute in Moscow. Scientists at the Institute are calling the new meteorites “Chebarkul”, after the town where the first fragments were collected from the lake of the same name. A formal name has yet to be announced.

1.2-inch (30 mm) slice of the meteorite showing nice shock veins, a few rounded grains called chondrules and already a bit of rusting due to the inevitable contamination by oxygen and water vapor. Click to enlarge. Credit: Laboratory of Meteoritics, Vernadsky Institute

The Russian meteorite resembles Park Forest, a meteor that came blazing out of the sky over the Chicago suburb Park Forest shortly before midnight March 26, 2003 and dropped numerous stones totaling about 40 lbs. (18 kilograms). One struck a fire station and another crashed through the roof of Noe Garza’s home and into a bedroom where a young boy was sleeping. Luckily, no one was hurt.

A 1.4-inch slice of the Park Forest meteorite that fell in 2003 shows similar shock veins and a shattered texture similar to the top image fo Chebarkul. Photo: Bob King

Chebarkul’s preliminary classification is L5 or LL5 chondrite; in plain English, that’s a stony meteorite with a low iron content heated to the point where much of its original mineral structure has re-crystallized. Gouged from the crust of a distant asteroid long ago, the huge boulder was pitched by the planet Jupiter into an Earth-crossing orbit and ultimately met its fate on Feb.15, 2013.  Park Forest is classified as an L5 and has a similar history.

The Institute further adds:
“According to Cyril Lorenz, meteorite scientist of the Laboratory of Meteoritics, further study of the samples revealed that meteor shower samples have different compositions  – chondrite, breccia (ie. broken rock) and impact melt. Thus (the) meteorite is a shock melted breccia.”


Animation of the orbit Chelybinsk meteoroid via Ferrin and Zuluaga. Meteoroid is the name given a meteor while still orbiting the sun before it enters Earth’s atmosphere.

Astrophysicists Jorge Zuluaga and Ignacio Ferrin just released a paper describing a preliminary orbit for the Chebarkul / Chelyabinsk meteoroid. They used video taken by a camera at the Revolution Square in the city of Chelyabinsk as well as other videos made by eyewitnesses in the nearby town of Korkino to calculate the trajectory of the body in the atmosphere.

Chebarkul appears to be an Apollo asteroid with an orbit that routinely crossed Earth’s. The Park Forest meteorite was also an Apollo family member. Illustration: Bob King

Although some uncertainties remain, the object is (was) a member of the Apollo family of asteroids, named for 1862 Apollo, discovered in 1932. Apollos cross Earth’s orbit on a routine basis when they’re nearest the sun. Chebarkul’s most recent crossing was of course its last.


Sasha Zarezina, 8, who lives in a small Siberian village, looks for and finds meteorites in the snow on Feb. 19, 2013. Video by Ben Solomon, New York TImes

Frame grab from BBC vidoe of local meteorite Boris Vasiliev describing his meteorite find on Chebarkul Lake. Click to see full video. Credit: BBC

More and more pieces of this erstwhile Apollo are turning up all the time. You’ll enjoy the video of Sasha hopping around in the snow digging for meteorite gold. Makes me wish I could be there not only looking for space rocks with the kids but covering the story with my camera.

Expedition of the Meteorite Committee of Russian Academy of Sciences (KMET RAN) collected the first samples of the “Chebarkul” meteorite. Click to enlarge. Credit: Laboratory of Meteoritics, Vernadsky Institute

Scientists study 53 tiny meteorites from Russian fireball

Posted on by
17

Pieces of the Russian meteorite fall are seen in a laboratory in Yekaterinburg on Monday, Feb.18, 2013. Black shock veins are visible in the broken specimen in the background if you look closely. Credit: AP Photo/ The Urals Federal University Press Service, Alexander Khlopotov

Scientists at Urals Federal University in Yekaterinburg have examined 53 meteorite fragments taken from the perimeter of the hole in frozen Chebarkul Lake. The largest is only 7 mm (about a quarter-inch) across; the smallest about one millimeter. Many are covered with dark fusion crust, a layer of melted and blackened rock from atmospheric heating.

The majority of the 53 pieces of the meteorite picked up around the hole at Chebarkul Lake displayed in the lab at the university in Yekaterinburg. The insides of the stones shows the typical pale gray, concrete-like texture of certain common chondrites. Credit: AP / The Urals Federal University Press Service, Alexander Khlopotov

The little stones are a common type of meteorite called a chondrite (KON-drite) that originated in the crust of an asteroid. A long-ago impact sent a fragment of the asteroid flying toward the inner solar system where it ultimately encountered Earth last Friday.

The Russian meteorite, which may receive the name Chebarkul, after the lake and town where it was found, contains about 10% iron-nickel, magnesium-rich chrysolite and sulfite, all common materials found in stony meteorites.

 

Look at how small the pieces are. I have to believe there are many more to be found from the powerful fireball. The sign reads: Meteorite Chebarkul. Credit: AP Photo / The Urals Federal University Press Service, Alexander Khlopotov

Chondrites are classified according to their iron content. Those with 15-20% nickel-iron metal are iron-rich and named “H” chondrites. Meteorites with a 7-11% nickel-iron content are classified as “L” chondrites, and those with the lowest amount of iron are the “LL” variety. Based on the lab’s description, it would appear that the fireball left a trail of L-chondrite crumbs. Let’s hope the hunters and scientists can follow the trail to the bigger ones.

** Update: I’ve recently learned via Russia TV and the New York Times this morning (Feb. 19) that local people are finding hundreds of small fragments buried in the snow. Read the full New York Times article and see more photos HERE.

Bizarre green meteorite NWA 7325 may be from Mercury

Posted on by
19

Wow, that’s what I call green! Green, glassy fusion crust coats one side of Ralew’s new meteorite. This is the largest of the 35 fragments, weighing just over 100g. Cube at right is 1 cm across. Click for larger version. Credit: Stefan Ralew

In April 2012 Stefan Ralew, a meteorite collector from Berlin, found himself staring at a spread of 35 green meteorite fragments for sale by a dealer in Morocco

“It was offered as a Martian (meteorite) but for me it was simply far too green,” said Ralew. Moroccan meteorite always keep an eye out for green rocks in the belief that they’re of Martian origin. Sometimes however they turn out to be nothing more than Earth rocks. Since this one was expensive, Ralew would have normally declined, but he noticed that the pieces had fusion crust, that frothy, typically dark coating of melted rock that forms when a meteorite is heated during its fall through the atmosphere.

Stefan Ralew Credit: Mirko Graul

“It was a big risk because of the high price,” said Ralew, but he sealed the deal and mailed off a piece to Dr. Tony Irving at the University of Washington, well-known for his expertise in meteorites from other planets.

After chemical analysis, Irving discovered that Ralew’s green rock was a completely new type of achrondrite (ay-KON-drite), a class of igneous meteorite that forms deep within the crust of larger asteroids and planet-sized bodies. In fact, Ralew’s green meteorite shared similarities with the planet Mercury, making it a one-of-a-kind.

Many of the more familiar achondrites that scientists and meteorite hunters have picked up here on Earth were blasted from the surface of Vesta by meteorite and asteroid impacts. Still others have been liberated from the moon and Mars. They drift through space until swept up by the ceaseless Earth. Scientists have done the math and arrived at the conclusion that meteorites from Mercury impacts should also by lying around in the deserts of the world, preserved by arid air and lack of rain. But no one had definitely identified a rock from Mercury until the green meteorite entered the scene.

A closeup of a polished, cut face of NWA 7325 shows striking green crystals of chromium diopside (a silicate mineral with chromium) and gray crystals of plagioclase, a rock also common in Earth’s crust. Click for larger version. There are a total of 345 grams (about 12 ounces) mostly in small fragments. Credit: Stephan Ralew

Other classes of achondrites called aubrites and angrites were once believed to have originated on the innermost planet, but further research points to their home on a yet-unknown asteroid or planet.

Mercury photographed by MESSENGER. The planet’s crust lacks iron and is pockmarked by countless craters. One of these impacts possibly sent NWA 7325 our way. Credit: NASA

Stefan’s meteorite, now classified as NWA 7325 (NWA=Northwest Africa, its find location), is a near-match for rocks examined from orbit by Mercury MESSENGER space probe. NWA 7325 is rich in magnesium, calcium and a silicate material laced with chromium that lends it an emerald sparkle, but it lacks iron. And that’s the key. Surface rocks on Mercury are likewise igneous and depleted in iron.

The match isn’t perfect. NWA 7325 has more calcium than it should and lacks the silicate mineral enstatite (common on Mercury), but that doesn’t worry scientists too much. Because the rock was excavated from deeper down in the crust, it would be expected to have its own unique qualities.

Mars meteorites show evidence of shock from impact in their crystal structures, and the same would be expected for rocks delivered to us from Mercury. Plagioclase, a very common mineral in Earth’s crust, and found in abundance in NWA 7325, has been completely melted, likely due to shock from the impact that sent it flying from the planet long ago.

Bubbly fusion crust on another fragment of Stefan’s meteorite. Click for larger version. Credit: Stefan Ralew

While the evidence points to a Mercury origin, we won’t really know for certain whether Ralew’s rock originated from the innermost planet until further studies are done. Scientists are still working to determinewhen those gorgeous green crystals formed as well as how long the rock coasted through space before arriving on Earth.

“Ultimately, only a sample return from Mercury may provide an answer,” wrote Irving in his group’s recent report on NWA 7325. In the meantime, Stefan’s meteorite stands as one of the most singular finds to date. It couldn’t have happened to a better guy. Ralew has a been a great friend of meteorite collectors and the scientific community for years. You can check out his website HERE.

Whopper of a meteorite dug up in Poland

Posted on by
Reply

The moon meets Jupiter last night as seen from my yard in Duluth, Minn. Orion is rising at lower right and Taurus’ brightest star Aldebaran is to the upper right of the moon. Photo: Bob King

I hope you were able to see last night’s Jupiter-moon conjunction. It was one of those sky events that made you stare and wonder even if you didn’t know you were looking at Jupiter. Too bad the aurora didn’t join in the show. Maybe next time.

One of the meteorite craters, now a pond, in the Morasko Meteorite Preserve. Credit: Wikipedia

In 1914 during World War I soldiers digging trenches on what’s now the northern edge of Poznan, Poland uncovered metal fragments that were later found to be meteorites. Further study of the site turned up eight craters and numerous iron meteorites covered in clay and rust.

Magdalena Skirzewska stands in the bottom of the 7-foot-deep hole next to the newly found meteorite. Copyright: Lukasz Smula

The first one dragged out from the trenches weighed 171 lbs. More have been found over the years bringing the total up to around 660 lbs. When cut, polished and etched with an acid solution, Morasko meteorites display an attractive pattern of gleaming iron-nickel crystals. Scientists estimate that a large meteorite broke up after entering Earth’s atmosphere, pelting the Polish landscape with numerous fragments around the year 3000 B.C.

A 69 gram slice of the iron-nickel Morasko meteorite measuring about 2.5 inches across. Metal meteorites like this one are though to originate in the cores of asteroids. Copyright: Lukasz Smula

Today the craters are protected in a 136-acre park known as the Morasko Meteorite Reserve. A bus will drop you off a half mile away. The largest of the eight is 328 feet across and 36 feet deep. Last month, meteorite hunters Lukasz Smula and Magdalena Skirzewska used metal detectors to discover the largest specimen to date buried over 7 feet deep in the dirt. The two search for the Adam Mickiewicz University in Poznan.

What a happy couple! The husband and wife team Lukasz Smula and Magdalena Skirzewska pose with their spectacular new Morasko meteorite find. Click image to see a gallery of pictures of the recovery operation. Copyright: Lukasz Smula

With the help of friends they dug down to the meteorite and built a chain hoist to raise the massive rock from its hole. At 660 lbs. it’s a real whopper and the largest meteorite ever found in Poland. It now resides in a considerably cleaner environment at Adam Mickiewicz University where it’s under study.

11.7 gram slice of the stony Novato, California meteorite. The shattered or brecciated texture tells us that the original meteorite was probably shocked and crushed by an earlier asteroid impact. Piece is about 1-inch across. Credit: Brien Cook

One of the great truths of meteorite hunting is that the best place to look for space rocks is where they’ve already been found. Invariably, more await the thorough hunter. Congratulations to Lukas and friends on their wonderful find!

Closer to home, another couple meteorites from the Oct. 17 San Francisco Bay area fireball has been found, bringing the total to at least four. Searching has been anything but easy, and now that rains have fallen, new finds will be more difficult as the rocks begin to weather. While we still are waiting for an official name, this new arrival from the asteroid belt is now classified as an L6 (low iron) stony meteorite.

Meteorite masquerade Part II – Stardust on a shingle?

Posted on by
2

Micrometeorites collected from a South Pole water well in Antarctica photographed at high magnification in a scanning electron microscope. Credit: Taylor, Herzog and Delaney

Two weeks ago Brandon Dunovant, who lives in a Chicago suburb, got the idea to collect the grit that had accumulated on his roof in hopes of finding micrometeorites. Maybe you’ve heard of this experiment or even tried it yourself.

As you might guess, micrometeorites are tiny extraterrestrial particles, most under than 2 millimeters in size. They derive from comets, asteroids and even the moon and Mars, entering the atmosphere gently enough to avoid vaporization.

A selection of various spheres and other melted materials discovered by Dunovant on his roof. A tiny percentage may be extraterrestrial. Credit: Brandon Dunovant

Some remain unmelted, others partially melt. Micrometeorites deliver an astonishing 20,000 to 30,000 tons of extraterrestrial material to Earth every year. Enough to inspire some to search their rooftops for asteroid dust. Dunovant got out the hose, sprayed down his shingles several times over and collected the washed-off debris by tying a fine-mesh on the ends of his downspouts. Since many meteorites are attracted to a magnet, he swept through his gritty pile with a powerful rare-earth magnet to separate potential meteorites from twigs and other detritus.

After an entire day tweezing apart the more interesting specimens from shingle grit, what was left made Brandon’s jaw drop.

“What I was looking at were aerodynamically-shaped black metallic pieces, some perfectly round, some pancake shaped, some bars, a couple buttons” and more. Dunovant wondered if they might be melted bits of the Orionid meteor shower which had peaked that weekend.

Closeup view of Dunovant’s collection of melted or cooked debris he collected from his roof. Credit: Brandon Dunovant

Despite their wonderful shapes and magnetic attraction, Brandon’s debris – like the materials found by many others who’ve tried the same experiment – contain few if any meteoric particles. According to Dr. Michael Zolensky, who curates cosmic dust for NASA, a typical Orionid meteor particle strikes the atmosphere at around 50 miles per second “pretty much guaranteeing that all the comet dust gets oxidized, melted, and
vaporized.” Like a leaf taking forever to fall, even a surviving Orionid needs a few days to make the journey from 60 miles up to the ground. That makes it even less likely that Brandon captured one.

Then there’s the size issue. Most micrometeorites are between 1 and 10 microns (a mircon’s a millionth of a meter or 1/1000 of a millimeter) across with bigger ones up to 1/10 to 3/4 millimeter in size. The largest piece, an elongated bar, pictured in Brandon’s gem jar photos above is 3 mm across; most of the others are 1.5mm or smaller.

Typical micrometeorite. It’s 1/5 of a millimeter across. Credit: Taylor et. all

Zolensky and others who researched micrometeorites especially in populated areas have discovered that much of what’s collected by amateurs is a combination of particles released from power plants, smokestacks, commercial boilers as well as tiny balls of clay from distant dust storms. The power plant emissions contain magnetite which responds well to a magnet.

Collection experiments in much cleaner places relatively free of industrial pollution like the ices of the South Pole and Greenland have yielded fine samples of extraterrestrial dust in some though not in all cases. When chemically analyzed, scientists find the same minerals as our found in larger meteorites though weighted toward the carbon-richer carbonaceous types.

Dr. Zolensky

Zolensky looked for micrometeorites at the South Pole years back and essentially found none. More recently, he and a team collected possible cosmic dust on a remote Pacific atoll and expect to have to wade through millions of terrestrial grains to find even a few tantalizing spheres from the asteroid belt.

So Brandon and others who’ve dragged a fine-toothed comb through their roof debris may possibly have something in their cache of curious particles, but the odds of real micrometeorites are slim indeed. Questions still remain. What causes the apparent aerodynamic shapes? I’ve searched fly ash photos online and can’t find any that quite match those in Brandon’s images. If you’d like to try the experiment on your own to see what’s drifting down on your house, click HERE for detailed instructions.

Both today’s blog and yesterday’s Part I are tinged with irony because Dr. Peter Jenniskens realized he was too hasty in evaluating the “rock” found outside Lisa Webber’s house after the recent California meteorite fall. On closer inspection, he determined it was indeed a meteorite. Read more about his change of mind HERE.

Meteorite masquerade – Part I

Posted on by
15

The rock at left, found by Lisa Webber of Novato, Cal. is not a meteorite despite its convincing appearance. At right is the first real meteorite from the fall found by Brien Cook from the fall. Credits: Peter Jenniskens (left), Brien Cook

Disappointing news. The rock that Lisa Webber picked up after it bounced off her roof in the wake of the October 17 California fireball wasn’t a meteorite after all. NASA’s Peter Jenniskens, who helped in the identification writes this:

“We examined the rock with a petrographic microscope yesterday and quickly concluded it was not a meteorite. I sincerely thought it was, based on what appeared to me was remnant fusion crust. On closer inspection, that crust was a product of weathering of a natural rock, not from the heat of entry.”

A slice of Brien Cook’s meteorite displays metal and darker, shocked areas – classic meteorite characteristics. Credit: Brien Cook

Another specimen weighing 66 grams was found in the fall zone (Mill Valley area) by meteorite hunter Brien Cook on Monday, October 22.

Cook cut three slices from the rock earlier today, and there’s no doubt it’s the real item. The flecks of metal, the dark, shocked areas – if that’s not a meteorite I’ll eat a rock. To my eye it resembles the Park Forest (IL.)  fall of March 26, 2003 which was classified as an L5 chondrite, a fairly common type of stony meteorite.

Meteorites are tricky. Like a Halloween costume, external appearances can mask a rock’s true identity. The Webber stone appears partially covered in a black fusion crust of melted rock typical of freshly-fallen meteorites. It even stuck to a magnet. Jenniskens peered under its disguise to reveal its real origin – Earth.

While the news is a bit of a let down, it does teach us how science works. Much as we’d like to believe our hunches about this or that aspect of nature, careful analysis may prove otherwise. Scientists and meteorite hunters alike know this is simply part of the process and move on. One question remains. What made the ding in Lisa Webber’s rooftop?

Speaking of roofs and shingles, ever heard of looking for tiny meteorites by sweeping a magnet through the grit that falls on your roof? Tomorrow we’ll explore the possibilities in Part II.

** UPDATE Oct. 25: In light of Brien’s find, Dr. Jenniskens has taken a second look at Lisa’s rock and is now convinced it’s the real thing after all. “An apology may have been too hasty,” said Jenniskens. “Lisa’s find is a genuine meteorite.” Ah, the tortuous path one must walk to find the truth!