Researchers Hunt For Naturally Occurring Quasicrystals

Image Caption: Field operations at the Listvenitovyi stream (clockwise): mapping the structural geology, examining mineral samples, extracting clay from areas along the stream, and panning the clay down to mineral separates. Credit: Paul J Steinhardt, Luca Bindi



An expedition to far eastern Russia, a 15,000 year old meteorite, secret diaries, smugglers, gold prospectors and bears; sounds like the plot to an Indiana Jones movie, right?

This is the story of two researchers looking for the origin of naturally occurring quasicrystals. Who knew science could be so exciting?

Writing in Reports on Progress in Physics, Paul J. Steinhardt and Luca Bindi reveal that new, naturally occurring quasicrystal samples have been found in an environment that does not have the extreme terrestrial conditions needed to produce them. This strengthens the case that they were brought to Earth by a meteorite that landed during the last glacial period, about 15,000 years ago.

“The fact that the expedition found more material in the same location that we had spent years to track down is a tremendous confirmation of the whole story, which is significant since the meteorite is of great interest because of its extraordinary age and contents,” said Steinhardt.

To add to the adventure movie plot of this expedition, Steinhardt and Bindi describe the journey that took ten scientists, two drivers, and a cook 230 kilometers into the Koryak Mountains of far eastern Russia to pan one and a half tons of sediment by hand, and survey local streams and mountains in the paper, “In Search of Natural Quasicrystals.”

Quasicrystals are a unique class of solids that were first synthesized in the laboratory by Israeli scientist Dan Shechtman in 1982. Shechtman was awarded the Nobel Prize for Chemistry in 2011 for this discovery.

The concept of quasicrystals was first introduced by Steinhardt and his student Dov Levine. Until their work, it had been believed that all solids, synthetic or natural, form ordinary crystals — materials whose entire structure is made of a single-type cluster of atoms that repeat at regular intervals, joining together in much the same way as identical tiles in bathroom tiling.

It was also thought that crystals could only have two-, three-, four- and six-fold symmetries; however, Steinhardt and Levine found a new theoretical possibility, which they dubbed quasicrystals. A quasicrystal has two or more types of clusters that repeat at different intervals with an irrational ratio, which allows all the symmetries that were thought to be forbidden, such as five-fold symmetry, to be possible.

Since their discovery in the laboratory, researchers have created over one hundred artificial quasicrystals that have been used in a variety of applications, from non-stick frying pans and cutlery to ball bearings and razor blades.

This is where the story gets interesting. Only one naturally occurring quasicrystal has been documented before this expedition, a sample in the Museum of Natural History in Florence, Italy. The sample was located and identified by Steinhardt, Bindi, and their collaborators in 2009. They found the sample to have the symmetry of a soccer ball, with six axes of five-fold symmetry forbidden to ordinary crystals. This discovery is what set off the incredible investigation to find the origin of the crystal.

Eventually, the research team found Valery Kryachko, who had removed the sample from a remote area of Chukotka in the Russian mountains in 1979.

Experiments in the summer of 2010 revealed that the sample was meteoric and had come from not just any type of meteorite, but a CV3 carbonaceous chondrite – a 4.5 billion year old meteorite formed at the beginning of the solar system.

“Now there was real motivation to turn this fantasy trip into a reality. It was a long shot, but if we could find even one sample there, it would prove the bizarre story we had put together beyond any shadow of doubt and provide new sources of material for studying this very strange meteorite that formed at the beginning of the solar system,” Steinhardt said.

Now that the expedition team has collected even more samples from the original site in Chukotka, there are a number of questions that can now be answered with further investigation.

“What does nature know that we don’t? How did the quasicrystal form so perfectly inside a complex meteorite when we normally have to work hard in the laboratory to get anything as perfect? What other new phases can we find in this meteorite and what can they tell us about the early solar system?

“At the moment, we are at the tip of the iceberg,” said Steinhardt.


Fonte: redorbit.com

Perseid meteor shower this weekend

The annual Perseid meteor shower is this weekend. You can expect to see up to one meteor each minute streaking across the sky. Meteors are tiny fragments of minerals that burn up upon hitting our atmosphere. Some Meteorites can be comprised up of minerals rich in silicon and oxygen. Other meteorites consist mainly of iron and nickel, while some are combinations of all four elements. Most are surprisingly tiny about the size of a grain of rice. They burn up in our atmosphere 30-60 miles above the surface of the earth. If a meteor does make it all the way to the ground, we call it a meteorite.

We often hear about a meteor shower occurring on one or two nights. The reality is that these shows begin way before they peak. This week the Perseid's are at their maximum on the night of the 11th and early morning of the 12th. You will, if it's clear and you get away from light pollution, be able to see shooting stars tonight and through the weekend. These pieces of debris are hurling trough space at 37 miles per second or about 133,200 miles per hour. At this speed they could cross the entire country in under 2 minutes. Not all meteors travel at the same speed. A fast meteor could go from the earth to the moon in about a minute and a half. That isn't as fast as the speed of light of course. If someone turned on a light on the moon you would see it a second and a half later here on earth.

Saturday and Sunday nights the moon will be in a waning crescent phase, therefore moonlight won't hamper viewing. The meteors tend to streak across the sky, but you will want to look toward the Perseus constellation, which is in the northeast part of the sky and forms an inverted "Y" shape. In the southern hemisphere you will have to look just above the northern horizon to see the meteors.

What to expect
If you are watching the show with kids you can have them try to find a satellite while waiting for a meteor. Satellites are quite easy to spot as they look like shooting stars but move across the sky at a much slower speeds. It can take a minute or more for a satellite to cross your field of view. I use the opportunity to talk about the earth, orbits and other planets to children during these events. On Saturday the 11th, leading into the 12th, expect about 25-60 meteors per hour. You won't see the meteors evenly spread out over time. You may see nothing for five minutes and then four or more in a row a minute later. Lie on a blanket and look up rather than stand. If you stand with your neck tilted up, you will have neck issues in the morning. On Sunday night, heading into the morning of the 13th there will be fewer meteors per hour, but still a nice show. The best time to see this will be around 2AM-3AM, but if you don't want to wait till then it's still worthwhile once it gets dark.


Fonte: Boston.com

Alberta meteorite sparks battle for sacred rock

A 150-kilogram meteorite that fell to earth centuries ago is pitting First Nations people northeast of Edmonton against the Royal Alberta Museum.

To the Cree, "pahpamiyhaw asiniy," is a sacred rock containing the face of the creator, but to scientists, it's a 4.5 billion-year-old meteorite, one of the largest in Canada.

The reddish-brown pitted chunk of iron is on display at the Royal Alberta Museum in Edmonton, but descendants of the rock's finders want it back.

"It needs to be taken care of by our people once again," says Vincent Steinhauer, president of Blue Quill First Nations College in St. Paul, Alberta.


"We'd like to repatriate the rock and welcome the rock back home where it should be," he said. "We have a way of worship. We were given that way of worship and we should be able to be allowed to do that."

The meteorite lit up the night sky hundreds of years ago, landing near where the town of Hardisty is today.

'Face of the creator'

When the aboriginal people dusted the rock, some thought they could see the face of the creator, said Steinhauer.

The meteorite was considered sacred, offering strength to those who asked.


But in the 1800s, missionaries seeing the people worship the rock, moved it to a church in Lac St Anne, near Edmonton.

Steinhauer said his people saw that as a bad omen.

"The prophecy goes that if that rock was ever to disappear then we would experience famine, pestilence, diseases and basically death," he said. "Ever since that rock was taken in the late 1800s that's basically what has happened to our people."

War followed by small pox, famine
Steinhauer points to the war between the Cree and the Blackfoot which claimed hundreds of lives, only to be followed by the arrival of small pox and the end of the bison.

The meteorite was eventually moved to the University of Toronto where it remained until returning to Alberta 10 years ago.

The Royal Alberta Museum became the official caretaker in 2001, but First Nations people were keen to have their sacred rock back.

Consultations were held over where the meteorite should go, but community leaders couldn't agree, said Chris Robinson, executive director of the museum.

"The elders believed that it would be inappropriate to return it to just one First Nation because it's meant to be for all," he said.

Museum provides access, security
"Because we were unable to resolve that, the understanding was the museum would be an appropriate location for the stone's care, for its long-term stewardship, for its access, and security and to offer free admission to those who want to pay their respects to the stone."

The museum will be talking to the community once again before the museum moves to a new downtown location in the years ahead, said Robinson.

The museum is planning a special space for the meteorite in a First Nations culture gallery.

However Steinhauer wants the rock returned to his people and become part of a ceremonial lodge being built at the college.

Treaty 6 and Treaty 7 First Nations are agreed, he said, leaving only Treaty 8 chiefs to decide at a future assembly, he said.

The move can only be finalized, however, at the behest of the museum and the province's culture minister.


Fonte: cbc.ca

Curiosity rover lands on Mars

NASA scientists and astronomers across the world are celebrating after successfully landing the Curiosity rover on the surface of Mars.


NASA successfully landed its $2.5 billion Mars Science Laboratory and Curiosity rover on the surface of the Red Planet, marking the most ambitious attempt to reach Mars in history.
It is a huge day for the nation, it is a huge day for all of our partners who have something on Curiosity and it is a huge day for the American people.

NASA administrator Charles Bolden
"Touchdown confirmed," said a member of mission control at NASA's Jet Propulsion Laboratory as the room erupted in cheers. "We are wheels down on Mars. Oh, my God."


A dusty image of the rover's wheel on the surface, taken from a rear camera on the vehicle, confirmed the arrival of the car-sized rover and its sophisticated toolkit designed to hunt for signs that life once existed there.


A second image arrived within seconds, showing the shadow of the rover on Mars.
When the landing was announced after a tense, seven-minute process known as entry, descent and landing, the room filled with jubilation as the mission team cheered, exchanged hugs and chief scientists handed out Mars chocolate bars.
President Barack Obama described the feat as a singular source of American pride.
"The successful landing of Curiosity - the most sophisticated roving laboratory ever to land on another planet - marks an unprecedented feat of technology that will stand as a point of national pride far into the future," he said in a statement.
"It proves that even the longest of odds are no match for our unique blend of ingenuity and determination."
Charles Bolden, the NASA administrator, echoed that sentiment and applauded all the nations who contributed to science experiments on board the rover.
"It is a huge day for the nation, it is a huge day for all of our partners who have something on Curiosity and it is a huge day for the American people," Bolden said.
Obama's science adviser John Holdren described the landing as "an enormous step forward in planetary exploration. Nobody has ever done anything like this. We are actually the only country that has landed surface landers on any other planet," he told NASA television.
"But this lander is vastly bigger, vastly more capable and much more complicated to bring in," he added. "It was an incredible performance."
However, success was anything but certain with this first-of-its-kind attempt to drop a six-wheeled chemistry lab by rocket-powered sky crane on an alien planet. NASA's more recent rover dropoffs were done with the help of airbags.
In the final moments, the spacecraft accelerated with the pull of gravity as it neared Mars' atmosphere, making a fiery entry at a speed of 21,240km/h and then slowing down with the help of a supersonic parachute.
After that, an elaborate sky crane powered by rocket blasters kicked in, and the rover was lowered down by nylon tethers, apparently landing upright on all six wheels.
Scientists do not expect Curiosity to find aliens or living creatures. Rather they hope to use it to analyze soil and rocks for signs that the building blocks of life are present and may have supported life in the past.
The project also aims to study the Martian environment to prepare for a possible human mission there in the coming years.
It has already been collecting data on radiation during its eight and a half month journey following launch in November 2011 from Cape Canaveral, Florida.
Earlier on Sunday, Mars program director Doug McCuistion called the science "absolutely crucial" to finding out if humans are alone, how Mars evolved from a wet to a dry planet and how accessible Mars may be for human explorers in the future.
"If we succeed, it will be one of the greatest feats in planetary exploration ever," he told reporters. "Our success rate has been pretty darn good recently."
Attempts by global space agencies since 1960 have resulted in a near 40 per cent success rate in sending landers, orbiters or other spacecraft for flybys to Mars. NASA has the best record.


Fonte: TheAge

Possible Valuable Meteorite Falls To Earth In St. Clair, Missouri, USA

Folks in St. Clair, Missouri are hunting for something that fell from outer space and could be worth a lot of money.  Mona Marler and her husband Rick were sitting on the deck of their St. Clair, Missouri home Wednesday night when they saw the fire ball.

And now she and others are searching for a possible meteorite. She`s seen shooting stars before but nothing like this.

Mona Marler: It was right there in front of us and you could see the fire you could see the tail you could see it burning and when it came down you could see it land in the field.

Meteorites can be very valuable.

Eric Gustaffon: They can be thousands of dollars there was a find in Kansas a number of years back where it was an extremely large meteorite that stay intact and do to the type of meteorite it was dubbed the million dollar meteorite.

Mona and her husband didn`t find anything overnight but they did smell something and believe they saw evidence of the meteor.

Mona Marler: You could see the smoke in the flashlight and smell something burning but it was not of wood it was like a sulphur smell.

Experts at the St. Louis Science Center say it`s possible a meteor landed nearby but very unlikely. Many are the size of a grain of sand and they usually burn up before they get to earth. And even though it seemed very bright it may be far away. A few years ago a fireball was seen by St. Louisans but it turned out it was hundreds of miles away.

Eric Gustaffon/St. Louis Science Center: The fall actually occurred in Wisconsin it was seen this far south as well.

Mona Marler: It`s a once in a lifetime thing.

She and her husband plan to use metal detectors as they continue to search the area in St. Clair, Roche Madden .


Fonte: Fox2now

Meteorite's left-handed molecules a blow to ET search

Never touted as easy, hunting for aliens just got a little bit harder.

It seems an excess of "left-handed" molecules, long assumed to be a signature of life, can be created inside asteroids through a non-biological process. That puts a damper on missions that intended to look for this chemical signature as evidence of biological activity on other worlds.

Molecules have handedness, or chirality, if their mirror-images cannot be superimposed upon each other, rather like your right and left hands. Life on Earth is built almost exclusively on left-handed amino acids, so scientists have assumed that a strong left-handed bias is a fundamental part of biochemistry.

Instruments on the European Space Agency's ExoMars and Rosetta missions are designed to search for an excess of left-handed molecules as an indicator of life.

But a new study found that meteorites collected from Canada's Tagish Lake also have a excesses of left-handed aspartic and glutamic acids, two amino acids that are common in terrestrial life.

Natural path

The researchers propose that, in the solar system's early days, heating as a result of radioactivity could have melted ice trapped deep inside asteroids. Liquid water then dissolved already present amino acids, which crystallised into mostly left-handed groupings.

Previous studies had seen small chiral excesses in amino acids from meteorites. But the new study is the first to propose a natural path for large left-handed enrichments in nonbiological materials, says team leader Daniel Glavin of NASA's Goddard Space Flight Center in Greenbelt, Maryland.

"As evidence mounts that [left-handed] excess occurs naturally across bodies in the solar system, any strategies designed to search for life based on looking for this excess require serious rethinking," says Alberto Fairen of the SETI Institute in Mountain View, California.

Even without chirality, though, the search for extra-terrestrial life can continue. "A swimming pool full of [left-handed] amino acids is not alive," says Harald Steininger, a project scientist for the MOMA instrument on ExoMars. "Life shows in many different aspects, and chirality is only one of them."

Journal reference: Meteoritics & Planetary Science, DOI: 10.1111/j.1945-5100.2012.01400.x


Fonte: NewScientist

Meteorite craters in Australia

Australia bears the scars of more than 30 major asteroid impacts, of the 176 worldwide.

A sample of Australia's 30-odd confirmed meteorite craters. (Illustration: Michael Payne)

EXPLORING HIS VAST CATTLE station in 1899, Walter Parke came upon a feature in the landscape he could not explain. A 15m-deep, bowl-shaped depression, larger than a football field, had been gouged out of the Central Australian desert. "One of the most curious spots I have ever seen in the country," he wrote in a letter to the anthropologist Frank Gillen. "An immense amphitheatre...To look at it I cannot but think it has been done by human agency, but when or why, goodness knows."

Further investigation revealed 12 craters pitting Parke's property at Henbury station, 115km south-west of Alice Springs. But their origin remained a mystery to Europeans until 1931, when local prospector, J. M. Mitchell, reported finding slugs of iron strewn across the site, "as though they had dropped from a molten mass falling at great speed".


Massive asteroid impact chances "extremely slim"

As one of the oldest and least geologically disturbed continents, Australia has a rich record of meteorite craters. Of 176 confirmed impacts worldwide, our country bears the pockmarks of 30 - and about 20 others await confirmation. Indeed, as you read this, another 1275 potentially hazardous asteroids (meteorite is the name of an asteroid once it has fallen to Earth) are orbiting in space - and that's just the ones we know about.

"An impact in Australia in the future is certain," says Duane Hamacher, an astronomer from Macquarie University in Sydney. "The recent flyby of '2005 YU55', a 400m asteroid - which passed closer to the Earth than the Moon - posed no threat to us, but had it impacted, it would have created a crater more than 6km wide and could have completely eradicated a large city like Sydney or Melbourne."

The 2005 YU55 was the largest object on record to pass this close to the Earth with our foreknowledge, but smaller meteors arrive surprisingly frequently.

"Estimates suggest that an impact or airburst (a meteor that explodes in the atmosphere) with the energy of one million tonnes of TNT will happen over Australian soil about once every few hundred to few thousand years," Duane says. "But the chances of us being affected by an impact event are extremely slim."


Meteorites recorded in Aboriginal Dreamtime

Compared with cataclysmic impacts throughout the Earth's history, the Henbury craters - formed 4200 years ago when a single meteor broke into pieces and spattered the desert - are only tiny dimples. The Arrernte people of Central Australia appear not only to have understood the craters' cosmic origins, but are likely to have witnessed the impact firsthand, Duane says. Eyewitness accounts seem to survive in oral traditions today. "Some of the Dreaming stories talk about stars falling out of the sky and hitting the ground," he says.

An Aboriginal man who accompanied Mitchell to Henbury in the '30s refused to approach within a few hundred metres of any crater. He told Mitchell that tjinka waru (fire spirit) lived in the yabo (rock hole), and that to drink water from the yabo would cause iron to rain down once more.

"So it seems to indicate either that the memory of this event has survived in oral traditions for thousands of years," Duane says, "or that people in the area later deduced something had come down from the sky."

Even as late as the early 1900s, most western scientists still attributed circular craters not to meteorites falling from the sky, but to ancient volcanoes. In this light, he says, the knowledge of the Arrernte people seems profound.

But Dreamtime stories don't explain all of Australia's craters this way. Take the story of Wolfe Creek Meteorite Crater, 880m in diameter and one of the world's best-preserved impact sites, formed in WA's Kimberley some 300,000 years ago, long before the local Djaru people could have seen it happen.

"Some of the Wolfe Creek stories talk about Rainbow Serpents coming up from under the ground and forming the crater (known to the Djaru as Kandimalal)," Duane says. Other stories claim that meteors seeded life on Earth, similar to the 'exogenesis' theory supported by some modern scientists. "Some cultures in the Central Desert associate objects falling out of the sky with the formation of life," he says.

Australian meteorite craters are ancient

In contrast to the relatively young craters at Henbury and Wolfe Creek, some of Australia's craters may date back as far as two billion years. "When you get that far back you start to lose the record," says Dr Alex Bevan, curator of mineralogy and meteoritics at the Western Australian Museum. "Erosion over time can actually remove the record completely. So the remnants of things that are two billion years old are pretty cryptic."

By studying the night sky and analysing well-preserved craters, scientists have built a strong understanding of meteorites, which are the fragments left over after an impact. They have discovered that most meteorites come from the asteroid belt between Mars and Jupiter. In space, rocks up to a few metres in size are termed meteoroids. Larger bodies, like the one that carved a 60km crater at Woodleigh, near Shark Bay, are called asteroids.

Once space rocks enter Earth's atmosphere, they are called meteors. Most meteors burn up and disintegrate harmlessly as 'shooting stars', but others reach our planet's surface - sometimes with catastrophic consequences.

"Strong evidence suggests the impact of an asteroid contributed to the extinction of the dinosaurs," Alex says. "Though it may not have been the only cause."

Evidence of such an impact lies buried in the Yucatán Peninsula, Mexico, in the form of the 65-million-year-old Chicxulub crater. The forces involved in impacts like these are almost unfathomable. The Chicxulub crater is about 300km in diameter. To create it, an asteroid 10km wide would have crashed into Earth with a force of two million hydrogen bombs. It would have lifted 10,000cu.km of dust into the atmosphere and sent giant tsunamis racing around the globe.

Based on the frequency of past events, experts estimate a 1-in-30,000 chance of an impact on this scale happening in the next century. If we see the asteroid approaching early enough, we might somehow be able to nudge it on a different path. "But a situation like the one in the movie Armageddon is simply not feasible in any way," Duane says. "If an asteroid that big were heading straight for Earth, and we only had days or weeks before it hit, all we could do is enjoy what time we have left!"


METEOR GLOSSARY

Asteroids
Rocky and metallic bodies orbiting the Sun, ranging in diameter from several metres up to hundreds of kilometres.

Meteoroids
The smallest members of the Solar System - chunks of debris from an asteroid or comet, ranging from a grain of sand to a few metres in diameter.

Meteors
Space rocks that have entered the Earth's atmosphere, creating a fiery streak of light (a shooting star).

Meteorites
Fragments of space rock left on Earth's surface.

Comets
Similar to asteroids, but characterised by massive tails of water vapour, gas and dust that are illuminated by the Sun.


Source: Australian Geographic (Issue 107, March - April, 2007)


Fonte: Australian Geographic