domingo, 24 de novembro de 2013

Visitor from planet Mercury at the Peabody Museum of Natural History

On the second floor of the Yale Peabody Museum of Natural History is a strange visitor from another planet.

No bigger than a small child's fist, the greenish rock was likely blasted off the surface of the planet Mercury 24 million years ago, and after traveling through the eons, fell on the Sahara Desert in Morocco, where it was eventually found by a desert traveler and later sold to a German collector.

The discovery was announced by Prof. Tony Irving of the University of Washington's Dept. of Earth & Space Sciences. He said that the origin of the rock was determined by its magnetic qualities, which match those of Mercury.

The Peabody is where the Mercury meteorite is getting its first public showing.

"Once we determined that it was extraterrestrial, the next question was `Where was it from?' " he said. "Of all the places where it may have come from -- Mars, the Moon, the asteroid belt -- it most closely resembles what we know about Mercury."

It's the first object believed to have come from Mercury. Meteors have been found that came from Mars and the Moon, but this is the first that likely came from the innermost planet.

The thought isn't that far-fetched, Irving said. For starters, Mercury is the smallest planet in the Solar System, with a little more than one-third the gravity of Earth. It also bears the scars of countless impact events, many sufficiently large to launch projectiles out to Earth's orbit and beyond. It also has almost no atmosphere.

Irving said that it has a number of qualities that point to a Mercurian origin: It has "native" or non-oxidized iron in small amounts. That, in and of itself, points to an extraterrestrial origin, Irving said.

But most significantly, it has the same magnetic qualities as what has been seen on Mercury. The ongoing NASA Messenger mission has measured the magnetic field of Mercury in detail, and the magnetic signatures of the object and Mercury seem to match.

The greenish rock has, in fact, the lowest magnetic intensity ever measured in any meteorite -- a magnetism that matches Mercury's modern field almost exactly, Irving says.

"This object does not have a counterpart with any rock that we know about," saidIrving, who has studied the rock with his colleagues since the spring of 2012.

The green coating is caused by the presence of chromium, combined with the heat of entering the Earth's atmosphere. The orange flecks were caused by terrestrial contamination, Irving said.

The meteor was one of about 35 space rocks found in the same locale, and all believed to be from a much larger meteor that crashed into what is now Morocco several thousand years ago.

Unfortunately for the researchers, all but one were tested with powerful magnets by the desert wanderers who found them. They do this to determine in the field if the rocks they find are indeed meteorites. This is not an issue for most space rocks, but for those that come from other planets, it makes exacting magnetic research impossible.

"To some people, not having an absolute answer is annoying," Irving said, "But, you're just going to have to live with that. The problem, of course, is that meteorites don't come with an address."

Irving said that it's not out of the question that the object is from somewhere else.

"But, if it is, that somewhere else is a really interesting place," he said.


quinta-feira, 21 de novembro de 2013

Mars Meteorite Reveals 1st Look at Ancient Martian Crust

A meteorite found last year in the Sahara Desert is likely the first recognized piece of ancient Martian crust, a new study reports.

The Mars meteorite NWA 7533 is 4.4 billion years old and contains evidence of long-ago asteroid strikes, suggesting that the rock came from the Red Planet's ancient and cratered southern highlands, researchers said.

"We finally have a sample of the Martian highlands, that portion of Mars that holds all the secrets to Mars' birth and early development," lead author Munir Humayun of Florida State University told via email.

"It's the part of Mars' history where the oceans and atmosphere developed, and where life would have developed if it ever did on Mars," Humayun added. "I will liken this to opening a treasure chest — it may take a while before we find the best treasures, but treasures aplenty lurk in this meteorite."

Humayun and his colleagues subjected NWA (short for northwest Africa, where the rock was found) 7533 to a series of analyses. The researchers determined the meteorite's age, for example, by determining that crystals within it called zircons formed about 4.4 billion years ago.

"This date is about 100 million years after the first dust condensed in the solar system," Humayun said in a statement. "We now know that Mars had a crust within the first 100 million years of the start of planet-building, and that Mars' crust formed concurrently with the oldest crusts on Earth and the moon."

The team also found high concentrations of normally rare elements such as nickel, osmium and iridium in NWA 7533, indicating that the rock formed in a region that was pummeled by chondritic meteors, which are relatively enriched in these materials.

Further, after measuring the abundances of certain elements within the meteorite, Humayun and his team were able to calculate a thickness for the Red Planet's crust.

"The amount of melting on Mars was low, sufficient to accumulate a 50-kilometer-thickness [31 miles] crust, but Mars evidently escaped the giant impact-style melting that affected the Earth and moon," Humayun told (Most scientists think the moon formed from material blasted into space when a planet-size body crashed into Earth more than 4 billion years ago.)

"This is the first reliable geochemical estimate of the thickness of Mars' crust, and it agrees with geophysical estimates from gravity and topography," he added.

Though researchers believe ancient Mars was relatively warm and wet, the team found no hydrous silicate minerals — which form in the presence of liquid water — within NWA 7533. Scientists will likely unearth more such puzzling details as they study the meteorite further, Humayun said.

"I expect more surprises as we dig deeper into our Martian treasure chest — some we will understand, and others may continue to befuddle us for a while to come," he said.


quarta-feira, 20 de novembro de 2013

Scientists Debate, Prepare for Killer Asteroid

Earthquakes, Tsunamis, Volcanoes. Now, add asteroids to the list of natural disasters that can threaten humanity and all life on our planet.

For decades, Hollywood films like Deep Impact andArmageddon have let moviegoers enjoy the terror of fictional earthbound asteroids from the safety of their seats.

But on February 15th of this year, residents of Chelyabinsk in central Russia discovered that the threat is as real as it gets.

That meteorite wounded more than 1,000 people - a pinprick compared to the one that probably wiped out the dinosaurs 65 million years ago, and far more benign than the meteor that exploded over Siberia in1908, leveling more than 2,000 square kilometers of forest.

Or the meteorite that hit present day Arizona, 50,000 years ago, and made a crater large enough to swallow up the entire city of San Francisco.

But those strikes were no flukes.

There are an estimated 10,000 known asteroids orbiting our region of the inner solar system. That’s just one percent of the million or more asteroids scientists believe to be our near neighbors in the inner Solar System.

Recently, at the American Museum of Natural History in New York, astrophysicist Neil deGrasse Tyson warned about....

" ...asteroids crashing to earth as meteorites or exploding in the atmosphere. That would be bad," he said.

He invited a group of concerned astronaut-scientists from the Association of Space Explorers, which included Thomas Jones.

“So one of these big explosions is capable of causing a global shutdown in agriculture and starving billions of people to death, as well as those who are killed by the actual explosion itself. Now small asteroids might level a city, but we could still lose hundreds of thousands of people," said Jones.

Asteroids are chunks of dark mineral rich rock that reflect almost no sunlight, so they are hard to spot from Earth. But infrared sensors on a space-based telescope could detect the heat they have absorbed from the sun.

That will be the job of the Sentinel Deep Space Telescope, bristling with infrared sensors, along with mapping and communications gear. The Sentinel mission is the brainchild of former astronaut Edward Lu and his B612 Foundation, which is committed to reducing the asteroid threat. Sentinel is scheduled to launch in 2018.

“Our telescope is sensitive enough that you actually can see a charcoal briquette against a black sky from ten times the distance from New York to Los Angeles," said Lu.

Once the asteroids are spotted and their orbits determined, an earthbound asteroid can be nudged slightly off course with a satellite deflector or a high velocity projectile, or blown up with nuclear weapons, causing it to miss its deadly rendezvous.

Much like Hollywood imagined it would in the 1957 science fiction film The Day the Sky Exploded.

But this time it’s the real world that would be saved.

Source: (Voice of America)

sexta-feira, 15 de novembro de 2013

Meteorite fall creates panic in Garo Hills

Biplab Kr Dey
TURA, Nov 14 – A meteorite falling in the areas bordering Bangladesh created panic among the residents of the Garo Hills region. The meteorite, which fell inside Bangladesh, lit up the night sky around 10.30 pm last night. It was eagerly watched by the residents living along these areas.

The meteorite fell close to the Dumnikura BoP in the Sherpur district of Bangladesh, just beside the international border and the impact was heard even 40 km away from the area where it fell. Dumnikura is a border outpost in the South Garo Hills, very close to where five police personnel were killed last week.

A resident of the neighbouring Dalu village in West Garo Hills, Dipu Marak, was witness to the incident.

He said, “We heard a loud noise around 10.30 pm last night and immediately rushed outside. We were in a state of shock. The meteorite lit up the night sky and narrowly missed us.”

Other local residents said the whole area shook under the impact of the fall and the light could be seen even on the Indian side of the border.

Panic-stricken people, who ran out of their houses, said that the sound resembled that of an aeroplane’s at a

close range.


segunda-feira, 11 de novembro de 2013

Why Is This Rock Worth $400,000?

Meteorite hunters risk prison and even death to find money from the sky, in the form of rare space rocks that are older than the Earth itself.

For 13 days in 2011 Michael Farmer and Robert Ward combed the southern desert of Oman, seeking treasure in the sands of Dhofar.

The pair were not on the southeast coast of the Arabian Peninsula to hunt for gold, gems, or fossils. They were there for meteorites. Oman's untouched landscape, monotone taupe background, and arid climate make for ideal hunting conditions. The trip was proving to be particularly successful—Farmer claimed a find that had once rested on the moon. He knew a collector who would want it, so he called from the field to arrange a $45,000 sale. For his part, Ward found a watermelon-size specimen, weighing nearly 100 pounds, that could easily be worth $60,000.

Then, on the 14th day of the trip, the two Americans were stopped at a roadblock on a mountain pass near Adam. Omani soldiers armed with M16s pulled them from their vehicles and started rifling through their belongings. "When they found that big rock of Robert's, they really went nuts," Farmer says. "The next thing I knew we were handcuffed together and thrown in the back of a truck."

Ward and Farmer were taken in shackles to a military base, locked in solitary confinement, and interrogated around the clock. Weeks later the bewildered Americans were given a 15-minute trial, which took place entirely in Arabic, and convicted of illegal mining.

Oman has no clear law against meteorite hunting. For centuries it had overlooked the rocks. Now that those stones have great value on the world market, the authorities in Muscat have become fiercely protective. The International Meteorite Collectors Association has been trying to find out the nation's legal guidelines, to no avail.

Convicted of illegal mining, Farmer and Ward were sentenced to serve time with criminals from India, Pakistan, Afghanistan, and Egypt. The Americans could hear riots in other parts of the prison. Their ordeal would stretch on for 54 days, until a retrial freed them. (Their attorney successfully argued that plucking rocks from aboveground could not be considered mining.) The meteorites were confiscated, and the two Americans are now banned from entering Oman.

For weeks after returning from the Middle East, Ward had had a hard time forcing himself to leave his Prescott, Ariz., home and when he did drive somewhere, to step out of his car. Although he can't imagine having the courage to jump from an airplane, chasing meteorites in the world's wilds makes perfect sense to him. Would he pay for this passion with his life? "I'm sure I will," he says. "But the question is are you going to die sitting on the sofa or doing something interesting?"

Space For Sale

The specimens meteorite hunters collect—and occasionally risk their lives to obtain—are an increasingly treasured commodity. "Like money from the sky," famed U.S. meteorite hunter Robert Haag once said.

In this field, cosmic geology meets market economics. A common stony meteorite, called a chondrite, can sell for $25 or less, but a slice of iron–nickel pallasite laced with olivine crystals can easily fetch a thousand times that. The stories behind them also matter. A meteorite collected after a witness sees its fall brings gobs of money. Meteorites that strike objects—cars, tin roofs, mailboxes—push the prices higher.

Most meteorites originate between Mars and Jupiter, where a belt of asteroids has lingered for 4.5 billion years, since the solar system was young. No rock on Earth is as old as a meteorite—all terrestrial material has been ground, melted, and reformed by plate tectonics. Meteorites have other, less common, origins. Meteor impacts on the moon or Mars can eject surface material into space that ends up on Earth. Last year a 10.5-ounce meteorite that originated on Mars fetched $94,000. A 4-pound lunar meteorite, the most expensive ever auctioned, sold for $330,000 in 2012.

"As the public becomes aware that they can own these things, we are seeing more and more interest," says Jim Walker, director of fine minerals for New York City–based Heritage Auctions. "It's the romance of having something not of the Earth, first. Second, the oldest thing that you can lay your hands on is a meteorite."

Meteors (a meteor is not called a meteorite until it hits Earth) carry with them the secrets of the universe, clues not only to the dawn of our solar system, but, many believe, to the origins of life on this planet. Scientists theorize that meteors seeded Earth with organic molecules, enabling life to form.

And so, meteorites are coveted by museums, scientists, and private collectors. Auction houses entered the game in the mid-1990s, catering to clients such as Steven Spielberg, Nicolas Cage, and Yo-Yo Ma. Such celebrity involvement has driven up prices. Now the Internet has opened the field to even more people—some interested in science, others only in the investment.

"There are many meteorite hunters and collectors who actively collaborate, to help to characterize newly found meteorites," says Mike Zolensky, a NASA astromaterials curator. "There are also some problems. Many collectors will get a sample and tuck it away. Many meteorites are not known to science for that reason."

Full-time hunters, including Farmer and Ward, often donate a portion of their discoveries to university labs in return for help with authentication. Carl Agee, director of the Institute of Meteoritics at the University of New Mexico, says hunters play a central role for science, even if they have ulterior motives. "You have to put a lot of effort into searching for meteorites," he says. "When the hunters find them and ask us to help classify them, it benefits everybody."

Agee notes that researchers interested in microscopic analysis don't have to bid against high-dollar collectors, the way museums do. "We have plenty of meteorites that are small, perfect for research," he says. "In the past few decades display pieces have become much more popular. The more demand there is, prices will naturally increase."

Randy Korotev, who studies lunar meteorites at Washington University in St. Louis, says the rise in interest—and value—is not welcomed by everyone. "I have colleagues, particularly those associated with museums, who are irate about this," Korotev says. "I cannot buy meteorites from Oman or northwest Africa with my NASA grant money because the U.S. government would consider them stolen property. Museum people think it's like stealing artifacts out of Egypt."

Farmer donates some finds but is also a professional and is certainly in it for profit. And, as his peers readily admit, he's one of the best. A meteorite paid for his house in Tucson, Ariz. Another put solar panels on the roof. And a third earned him a trip to Bora Bora with his wife.

Like many others in the business, Farmer is both a meteorite hunter and a dealer. His most famous discovery—a 117-pound pallasite unearthed on a farm in Canada—was purchased by the Royal Ontario Museum in Toronto for $600,000. Like every hunter, though, Farmer has had his share of disappointments. On the patio behind the kitchen sits a brick-size stone he purchased for $10,000. It's what people in this field call a meteorwrong—a worthless piece of terrestrial rock. "I keep it around," he says, "as a reminder. You're not always right."

Inside his home, meteorites recovered on a recent trip to Chelyabinsk, Russia, lay scattered across the glass top of the dining room table. Tiny ones—no larger than a grain of sea salt—dot paper towels. Others rest in glass vials. Walnut-size nuggets fill white cardboard cartons and wooden cigar boxes. Those waiting to be sorted sit in two glass Pyrex dishes. "A few months ago this sucker was out past Mars and now it's here," he says, holding up one of his finds. "Makes you feel insignificant."

Despite his candid demeanor, the nature of his work can be shadowy. He balks at describing how he transported all those rocks home from Chelyabinsk. "I use methods I'd prefer not to discuss," he says with a smile. "My Russian friends might behead me."

Source: popularmechanics

sexta-feira, 8 de novembro de 2013

Scientists predict Chelyabinsk like meteorite event ahead

Scientists have predicted Chelyabinsk like meteorite explosion events in the future also, which may have much more hazardous effects on the Earth.

At a recent panel of the Association of Space Explorers in New York, physicist and former astronaut Ed Lu warned that there are about 10,000 known asteroids orbiting our region of the solar system.

Lu’s B612 Foundation is planning to help launch a space-based infrared telescope in 2018 that can detect the heat emitted by asteroids, map their position and orbit, then provide a warning in time to mount an international effort to deflect the more dangerous ones.

According to recent scientific studies published in the journals Nature and Science, the possibility of these dangerous asteroids entering Earth’s atmosphere may be greater than previously believed.

Physicist Paul Wiegert of the University of Western Ontario and an author of a study of the Chelyabinsk meteor said, “Chelyabinsk didn’t really create as much damage as we might have expected, and that’s a good thing. The flip side is that we are now starting to discover that events like the Chelyabinsk event are occurring more frequently than we had originally anticipated. But we’ll have to wait a little while longer and collect a little more information before we can know for sure.”

The scientists at the University of California described the 20-metre Chelyabinsk meteoroid strike that injured around 1200 people as “a wake-up call”.

Chelyabinsk was the largest meteoroid strike since the Tunguska event of 1908, and modern technology provides an unprecedented opportunity to study such an event, researchers said. The Chelyabinsk meteorite belongs to the most common type of meteorite, an “ordinary chondrite.”

Meanwhile, the officials at NASA’s Near Earth Object program, which scans the heavens for dangerous objects, say the space agency is reassessing what size rocks to look for and how often they are likely to hit.