Posts Tagged ‘meteorite

Russia Meteor Not Linked to Asteroid Flyby

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A meteor seen flying over Russia on Feb. 15 at 3:20: 26 UTC impacted Chelyabinsk.

A meteor seen flying over Russia on Feb. 15 at 3:20: 26 UTC impacted Chelyabinsk.

New information provided by a worldwide network of sensors has allowed scientists to refine their estimates for the size of the object that entered that atmosphere and disintegrated in the skies over Chelyabinsk, Russia, at 7:20:26 p.m. PST, or 10:20:26 p.m. EST on Feb. 14 (3:20:26 UTC on Feb. 15).

The estimated size of the object, prior to entering Earth’s atmosphere, has been revised upward from 49 feet (15 meters) to 55 feet (17 meters), and its estimated mass has increased from 7,000 to 10,000 tons. Also, the estimate for energy released during the event has increased by 30 kilotons to nearly 500 kilotons of energy released. These new estimates were generated using new data that had been collected by five additional infrasound stations located around the world – the first recording of the event being in Alaska, over 6,500 kilometers away from Chelyabinsk. The infrasound data indicates that the event, from atmospheric entry to the meteor’s airborne disintegration took 32.5 seconds. The calculations using the infrasound data were performed by Peter Brown at the University of Western Ontario, Canada.

“We would expect an event of this magnitude to occur once every 100 years on average,” said Paul Chodas of NASA’s Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. “When you have a fireball of this size we would expect a large number of meteorites to reach the surface and in this case there were probably some large ones.”

The trajectory of the Russia meteor was significantly different than the trajectory of the asteroid 2012 DA14, which hours later made its flyby of Earth, making it a completely unrelated object. The Russia meteor is the largest reported since 1908, when a meteor hit Tunguska, Siberia….
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Written by physicsgg

February 16, 2013 at 6:41 am


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How to Find a Meteorite in 5 Steps

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A chrondite meteorite in situ in Rub’ al Khali, Saudi Arabia.
Image: Creative Commons | Meteorite Recon

To start, get permission to keep what you find, find a barren spot like the Mojave Desert or Great Plains, and track down ‘dark flight trajectories’ from recent fireballs
By Natalie Wolchover and Life’s Little Mysteries
Earth is under constant bombardment by space rocks. When they crash and burn through the atmosphere, most of the debris gets lost to the oceans, while some is buried or gradually weathered away. Nonetheless, plenty of chunks of fallen meteors, or meteorites, are strewn across the accessible parts of the planet. So far, more than 40,000 meteorites have been found and catalogued, and countless more are still out there, waiting to be chanced upon.

If you need further incentive for finding something that was forged at the birth of our sun and contains secrets about the nature of our solar system, there’s this: Space rocks are worth as much as $1,000 per gram. The following tips will get you started on your search, but be warned: This extraterrestrial treasure hunt requires hard work and dedication.

Step 1. Get permission
Before you plan a meteorite hunt, make sure that if you find one, you’ll be allowed to keep it. Space rocks found in national parks belong to the federal government and cannot legally be kept, said David Kring, a meteorite scientist at the University of Arizona’s Lunar and Planetary Institute……

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Written by physicsgg

May 3, 2012 at 4:36 pm

Space Diamonds Reveal Supernova Origins

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Collisions in space may be behind mysterious diamonds found in meteorites.
By Brian Jacobsmeyer, ISNS Contributor
Inside Science News Service

Space diamonds may now be an astrophysicist’s best friend.
For years, scientists have found DNA-sized diamonds in meteorites on Earth. New research suggests that these diamonds spring from violent cosmic collisions, which may help scientists unravel mysteries surrounding exploding stars — the birthplaces of ancient materials that predate our solar system.

Although diamonds are rare on Earth, scientists believe that minuscule “nanodiamonds” abound in space. Researchers have been trying to decipher the origin of these enigmatic minerals for decades.

On Earth, traditional diamonds are forged deep underground under intense heat and pressure over the course of billions of years. Space diamonds, however, can form in a millionth of a millionth of a second according to new research appearing in the journal Physical Review Letters.

“The transformation is quite astonishing,” said Nigel Marks, a materials scientist at Curtin University in Perth, Australia, and coauthor of the research paper. “I never would have imagined this was possible.”

Marks simulated space dust collisions on his computer and found that diamond formation didn’t require blistering temperatures or crushing pressures. Instead, in simulations, diamonds formed when carbon-containing dust grains smashed together at speeds exceeding 10,000 miles per hour.

Within the original grains, spherical fullerenes — soccer-ball-shaped carbon molecules — enclose one another like Russian nesting dolls. Together, these concentric molecules compose layered carbon “onions.”

When the carbon onions slammed into each other, the molecules flattened, squeezed and linked together. During this process, the onions rearranged themselves into hexagonal shapes indicative of diamond structure.

If they collided at high enough speeds, then the carbon onions were destroyed. And if the particles weren’t moving fast enough, then the carbon onions did not complete the transition to diamonds. The researchers found that the narrow speed range that facilitates nanodiamond formation is common in space.

“They found that there’s sort of a sweet spot,” said Andrew Davis, a geochemist at the University of Chicago, who was not affiliated with the research. “If you can do it just right, you can make nanodiamonds. That was interesting.”

With this new model for nanodiamond formation, scientists hope to unlock some of the secrets these diamonds contain. Until now, scientists have only extracted limited information from nanodiamonds partly because they didn’t have a suitable theory for their formation, said Marks.

“There’s a huge message embedded in the nanodiamond,” said Marks. “[Researchers] just couldn’t figure out what it was.”

Forms of elements such as gaseous xenon with different amounts of neutrons have been found inside meteorite nanodiamonds. Called isotopes, these variants of the same elements convey information about exploding stars from earlier in the universe’s history. Different ratios of isotopes are produced in different nuclear reactions, giving scientists clues as to what types of dying stars gave birth to these isotopes.

According to Marks and his team, xenon is likely incorporated into carbon onions before they collide and produce nanodiamonds. By better understanding where these embedded isotopes originate, scientists can glean new information about the death of stars and the origins of our solar system.

Several competing theories, however, suggest nanodiamonds were formed differently than Marks’ research indicates. For instance, some scientists think that shock waves from exploding stars may have created nanodiamonds. Intense pressure and heat from the shock wave could also have led to the implantation of noble gases like xenon.

But all theories put forth so far have been hampered by limited experimental evidence. Because nanodiamonds are so small, it’s been extremely difficult to look at them individually.

To help resolve this issue, Marks and his colleagues hope to translate their simulations into lab experiments in the coming months. By creating nanodiamonds on Earth, the research team could produce large enough samples to analyze.

The samples could also be used for biomedical and industrial applications.

Manufacturers already create similarly sized nanodiamonds to use as drug markers or dry lubricants. Current methods require extremely high temperatures, though, limiting the types of materials that can be coated. Using the method put forth by Marks and his team, manufacturers could create coatings for materials that melt relatively easily, such as steel.

High speeds on such a small scale can be tricky, however.

“I think it’s probably not trivial to accelerate these grains to 5 kilometers per second,” said Davis. “That’s a hard thing to do in a lab.”

Nonetheless, Marks hopes that his simulations will guide future experiments.

“Now that we know this possibility exists, we want to go on and figure out what you can do with it,” said Davis….

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Written by physicsgg

February 15, 2012 at 3:19 pm


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The chemistry of exploding stars

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Meteorite contains evidence of formation of sulfur molecules derived from the ejecta of a supernova explosion

Fundamental chemical processes in predecessors of our solar system are now a bit better understood: An international team led by Peter Hoppe, researcher at the Max Planck Institute for Chemistry in Mainz, has now examined dust inclusions of the 4.6 billion years old Murchison, meteorite, which had been already found in 1969, using a very sensitive method. The stardust grains originate from a supernova, and are older than our solar system. The scientists discovered chemical isotopes, which indicate that sulfur compounds such as silicon sulfide originate from the ejecta of exploding stars. Sulfur molecules are central to many processes and important for the emergence of life.

Star dust from a supernova. The electron microscopic image shows a silicon carbide grain from the meteorite Murchinson. The approximately one micrometre small grains originate from a supernova as an isotopic analysis has shown. Isotopes are forms of an element with different weights. Picture: Peter Hoppe, Max Planck Institute for Chemistry © Peter Hoppe, MPI for Chemistry

Models already predicted the formation of sulfur molecules in the ejecta of exploding stars – the supernovae. Scientists from Germany, Japan and the U.S. now provided evidence to substantiate the theory with the help of isotope analyses of stardust from meteorites.

The team around the Mainz Max Planck researcher Peter Hoppe initially isolated thousands of about 0.1 to 1 micrometre-sized silicon carbide stardust grains from the Murchison meteorite, which was already found on Earth in 1969. The stardust grains originate from a supernova, and are older than our solar system. The researchers then determined with a highly sensitive spectrometer, the so-called NanoSIMS, the isotopic distribution of the samples. With this technique an ion beam is shot onto the individual stardust grains and releases atoms from the surface. The spectrometer then separates them according to their mass and measures the isotopic abundances. Isotopes of a chemical element have the same number of protons but different numbers of neutrons.

In five silicon carbide samples the astrophysicists found an unusual isotopic distribution: They measured a high amount of heavy silicon and a low amount of heavy sulfur isotopes, a result that does not fit with current models of isotope abundances in stars. At the same time they were able to detect the decay products of radioactive titanium which can be produced only in the innermost zones of a supernova. This proves that the stardust grains indeed derive from a supernova.

A proof for the model of the chemistry of the ejecta of supernovae

“The stardust grains we found are extremely rare. They represent only about the 100 millionth part of the entire meteorite material. That we have found them is very much a coincidence – especially since we were actually looking for silicon carbide stardust with isotopically light silicon,” says Peter Hoppe. “The signature of isotopically heavy silicon and light sulfur can only be plausibly explained if silicon sulfide molecules were formed in the innermost zones in the ejecta of a supernova.” Afterwards, the sulfide molecules were enclosed in the condensing silicon carbide crystals. These crystals then reached the solar nebula around 4.6 billion years ago and were subsequently incorporated into the forming planetary bodies. They finally reach the Earth in meteorites which are fragments of asteroids.

Carbon monoxide and silicon monoxide were already detected in infrared spectra of the ejecta of supernova explosions. Although models predicted the formation of sulfur molecules, it has not yet been possible to prove this. The measurements on silicon carbide stardust now provide support to the predictions that silicon sulfide molecules arise a few months after the explosion at extreme temperatures of several thousand degrees Celsius in the inner zones of supernova ejecta.

The meteorite studied was named after the Australian city of Murchison, where it was found in 1969. For astronomers, it is an inexhaustible diary about the formation of our solar system, as it has remained almost unaltered since its formation. Besides the stardust inclusions from the ejecta of a supernova Murchison also transported dust to the Earth which has been formed in the winds of giant red stars. Through further analyses, the researchers hope to learn more about the origin of their parent stars.

Written by physicsgg

January 20, 2012 at 4:10 pm

Nobel prizewinning quasicrystal fell from space

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It came from outer space (Image: Luca Bindi and Paul Steinhardt)

A Nobel prizewinning crystal has just got alien status. It now seems that the only known sample of a naturally occurring quasicrystal fell from space, changing our understanding of the conditions needed for these curious structures to form….
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Read also: The quasicrystal from outer space

Written by physicsgg

January 3, 2012 at 5:04 pm

Posted in Chemistry, SPACE

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The world’s natural firework display

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Perseid meteor shower lights up the night sky around the globe

View from International Space Station (Ron Garan)

…===> … Read the rest of this entry »

Written by physicsgg

August 14, 2011 at 1:32 pm


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DNA Building Blocks Can Be Made in Space

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NASA-funded researchers have evidence that some building blocks of DNA, the molecule that carries the genetic instructions for life, found in meteorites were likely created in space. The research gives support to the theory that a “kit” of ready-made parts created in space and delivered to Earth by meteorite and comet impacts assisted the origin of life.

Written by physicsgg

August 9, 2011 at 7:36 am


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