segunda-feira, 30 de dezembro de 2013

Chelyabinsk meteorite hit the Earth like a warning shot fired from space

The meteorite is providing invaluable information to help protect against larger rocks that might pose a serious threat to Earth

The meteorite fireball that fell over Chelyabinsk briefly burned 30 times brighter than the sun. Photograph: AP

Just after sunrise on 15 February 2013, as commuters made their way along snow-covered roads to Chelyabinsk in south-west Russia, the clear blue sky was torn by a hurtling lump of space rock.

The meteorite appeared without warning, out of the sun, on a shallow trajectory. It thumped into the atmosphere at 12 miles per second and became a fireball. For a moment, the rock burned 30 times brighter than the sun.

Viktor Grokhovsky, a researcher at Ural Federal University, 200km to the north of Chelyabinsk, missed the beautiful, terrifying spectacle that morning, but within minutes was watching video of the event. He spent the rest of the day assembling a search party. The first of several set out at first light the next morning to interview eyewitnesses and recover pieces of the fallen rock.

"It was rather easy to find fragments in the first days after the meteorite fell, because the chunks left holes in the snow," Grokhovsky told the Guardian. But as more snow fell over the next two weeks, the holes became covered over. The search was called off until the snow began to melt in the spring.

Nothing the size of the Chelyabinsk meteorite had fallen to Earth in 100 years, and never over an urban centre where its dramatic arrival would be captured by CCTV and dashboard video cameras installed by Russians wary of insurance scams and crooked police.

"This was the first time in modern, medieval or ancient history when a meteorite fell in an area with a high density population. This type of meteorite is rare and a lot of material fell. All these factors give excellent opportunities for extraterrestrial substance research. The hazard from asteroids and comets, people's behaviour in emergencies, and the shortage of astronomical education are all on the agenda," said Grokhovsky.

After the flash came the bang. The meteorite exploded with a force around 30 times that of the atom bomb dropped on Hiroshima, or 500 kilotonnes of TNT. The shockwave knocked people off their feet and shattered windows in thousands of apartments. The Earth rang to the blast, with vibrations picked up by seismic sensors 4,000km away.

Nobody was killed, but the blast injured more than 1,200 people. Many had cuts from flying glass. Others suffered retinal burns from watching the fireball, or burns that left their skin peeling. The toll was slight because the 20-metre-wide meteorite exploded so high, more than 20km above the ground.

Grokhovsky's search parties came back with more than 700 fragments of meteorite and scores of eyewitness accounts from locals. One of his expeditions had skied 50km, from village to village, beneath the meteorite's path. He used the information they gathered, along with public video footage, to piece together the trajectory of the rock and predict where much of it must have landed.

On the back of that work, a search party was sent to investigate a large hole that had appeared in ice covering a lake on the slopes of the southern Ural mountains. The team collected fragments of chondrite that matched other chunks of the meteorite. When Grokhovsky called on colleagues to measure the magnetic field at the lake, they found an anomaly in their readings near the hole. "Their analyses convinced us that exactly this meteorite had landed in the lake," Grokhovsky said.

It was October before a team of professional divers finally searched the lake, but the wait was worthwhile. "They found a 650kg meteorite fragment deep in the sludge," said Grokhovsky. The lump was so fragile it split in three when they weighed it. The heaviest chunk is now on display in the Chelyabinsk museum of local history.

"The most powerful impression for me personally was work on the night of 17 to 18 February. It was that moment when me and my colleagues from Ural Federal University's nanotech centre determined the meteorite's origin and the substance of the chunks which were collected not far from the hole in the ice," Grokhovsky said.

The recovery of so much of the meteorite will transform research in the field. Scientists can use the fragments to understand the rock's cosmic origins and its properties, all useful information to protect against a larger rock that might pose a serious threat to Earth in the future. Ominously, researchers have already discovered that there must be ten times as many potentially dangerous asteroids out there with sizes of the order of tens of metres as previously thought.

"It is very hard to overestimate the importance of the meteorite's recovery from the lake. The total mass of extraterrestrial substance that was pulled up weighed more than all the samples which were delivered to Earth by the [US] Apollo and [Soviet] Luna missions," said Grokhovsky.


domingo, 29 de dezembro de 2013

The Hunt For Meteorites Begins In Antarctica

Antarctica is one of the best places on Earth to spot these fallen stars.

Each winter — which is summer in down south — a team of geologists camps out on an Antarctic glacier in the middle of nowhere, often where no human has ever tread. It's kind of like a space voyage, but a lot cheaper.

And it's the meteorite that's done most of the traveling.

"It's an amazing journey to think about, and a very precious rock," says Jani Radebaugh, a planetary scientist at Brigham Young University, from a tent about 500 miles from the South Pole. She's one of eight in an expedition group funded by NASA and based out of Case Western Reserve University.

Each day, she and her team members set out on snowmobiles, scanning the horizon for black specks — samples that will eventually make it to NASA's Johnson Space Center in Houston.

Most of the meteorites have been lying on the ice since they landed on Earth millions of years ago. The glacier keeps them fairly sterile, preserving the specimens almost as a deep freezer would. And the white-and-blue expanse gives a good backdrop for the search, which is a little like looking for an ant on a white tablecloth — if the tablecloth were million-year-old, mile-thick blue ice.

"As soon as you see that dark black fusion crust on the outside, you just get so excited," Radebaugh says. "Everyone jumps up and just starts waving their hands."

Then, they drop to their knees to measure, photograph and collect the meteorite. They get excited because these rocks can offer precious information — like clues about the early solar system, and whether there was ever life on Mars.

The meteorite hunters are a hardy crew. Sleeping on a creaky slab of ice hundreds of feet thick can be a bit unnerving.

"The only thing I can hear is the popping of the glacier underneath me," Radebaugh says. "You're sitting on a giant, moving body of ice. And sometimes you forget that, until you hear the pops and groans. It's really magical."

Radebaugh and her colleagues will spend close to two months out on the ice, one group of a long line that has collected more than 20,000 meteorites in the last few decades.

This year's expedition is a little different from past years. It's a lot shorter — delayed by about a month because of the government shutdown. Bad weather has prevented the other half of the eight-person crew from landing, despite efforts to smooth a landing strip on the ice for the ski-equipped planes.

The team that is on the ground is doing its best, enjoying 24 hours of daylight and the thrill of finding chunks of other worlds.

They'll celebrate New Year's Eve under the midnight sun, listening to the popping glacier, and perhaps dreaming about popping a cork.


domingo, 15 de dezembro de 2013

China successfully lands robotic rover on the moon / with video

A Chinese robotic rover landed on the moon Saturday, becoming China's first outpost on another world after a rocket-powered descent to an unexplored barren volcanic plain.

Chang'e 3 returned real-time imagery of the moon from an on-board descent
camera. Credit: CCTV

The ambitious Chang'e 3 mission also achieved the first "soft landing" on the moon in 37 years, and it made China the third country to pull off the feat after the United States and Russia.

Touchdown occurred at about 1311 GMT (8:11 a.m. EST; 9:11 p.m. Beijing time). China said the lander was aiming for a landing in the Bay of Rainbows, a dark basin on the moon's near side filled with lava that congealed billions of years ago.

The Chang'e 3 lander dropped from a low-altitude orbit, using its variable-thrust main engine to reduce its velocity from orbital speeds of 1.7 kilometers per second, or about 3,800 mph, to nearly zero.

Chinese media reports said the lander was designed to halt its descent about 300 feet above the lunar surface to ensure the landing zone was clear of hazards such as boulders or steep slopes.

Once the probe's autonomous hazard detection system was satisfied the landing site was safe, Chang'e 3 resumed its descent before shutting off its engine about 10 or 15 feet above the moon. Chinese officials said
they designed the craft's landing sets with impact suppressors similar to shock absorbers.

Laser and radar ranging sensors supplied altitude and terrain data to Chang'e 3's computer, giving the lander navigation cues during the final descent.

Such on-board smarts have never been used on an unmanned lander before.

Chinese state television broadcast the landing live, showing animation and real-time imagery from Chang'e 3's camera.

Engineers at the Beijing Aerospace Command and Control Center, who appeared stoic and reserved before landing, erupted in applause and flashed smiles when the touchdown was announced.

A few minutes later, officials confirmed the 12-foot-diameter lander's
solar panels deployed.

A six-wheeled mobile rover was expected to detach from the lander later this weekend, perhaps as soon as a few hours after touchdown. Officials said the lander would first vent leftover propellant.

The rover will drive several miles around the landing site, surveying the dusty charcoal-colored landscape for several months.

China named the rover Yutu after soliciting suggestions from the public. Yutu translates as "Jade Rabbit" in English.

In Chinese mythology, Yutu is a rabbit who accompanies the goddess Chang'e to the moon.

Yutu will beam 3D imagery of the moon back to Earth and measure the composition of lunar soils and rocks.

The rover is also equipped with a ground-penetrating radar to survey the structures below the moon's surface.

"As the rover drives along the lunar surface, it will be as if it can cut and see 100 meters [328 feet] below," said Ouyang Ziyuan, a researcher at the China Academy of Sciences and senior advisor to China's lunar exploration program, in an interview with Chinese state television.

Ouyang said the rover will use nuclear batteries to keep warm during lunar nights. Temperatures dip as minus 292 degrees Fahrenheit (minus 180 degrees Celsius) during nights on the moon, exposing delicate electronics to cold conditions for two weeks.

Yutu is smaller than NASA's Curiosity rover currently exploring Mars. The Chinese lunar rover stands about 4.9 feet tall and has a mass of about 140 kilograms, or 308 pounds.

The lander and Yutu rover will snap photos of each other, and the mission's stationary lander will operate for up to a year doing its own investigations. The lander's instruments include an ultraviolet telescope to observe the Earth and other scientific targets.

It could take several days to pinpoint the probe's exact location on the

An initial position estimate put the landing site at 44.12 degrees north latitude and 19.51 degrees west longitude. The estimate will be refined over the coming days.

Two European Space Agency tracking antennas were called up to receive signals from Chang'e 3 on Saturday. One of the European-owned ground stations in Australia tracked the lander throughout its descent, and another near Madrid was on standby to pick up a signal from Chang'e 3 a few hours after landing.

The New Norcia station near Perth received a strong signal from Chang'e 3 throughout its descent, according to an ESA official at the European Space Operations Center in Darmstadt, Germany.

Chang'e 3's ground team at the Beijing Aerospace Command and Control Center monitored the landing through China's own communications antennas, but ESA's ground stations were configured to provide navigation support.

Using quasars, bright beacons at the hearts of distant galaxies, ESA can attain precise position estimates for spacecraft flying through deep space. Chang'e 3 will be the first time the technique -- Delta-Differential One-Way Ranging, or delta-DOR -- has been used for a stationary probe on the surface of another celestial body.

In the delta-DOR technique, engineers compare the exact time a spacecraft's signals are received at two ground stations -- in Australia and Spain for the Chang'e 3 mission. The antennas simultaneously track a quasar, which have known locations, to correct for errors induced by radio signals passing through the Earth's atmosphere.

China's moon landing comes after the country launched two orbiters to the moon in 2007 and 2010.

One of the satellites, Chang'e 2, left the moon and became China's first interplanetary probe. Chang'e 2 flew by asteroid Toutatis in December 2012, returning the first close-up images of the potato-shaped object.

According to Ouyang, considered the father of the Chang'e lunar program, China will dispatch a robotic mission to the moon in a few years to return rock samples to Earth. The Chang'e 5 mission will launch in 2017, previous Chinese news reports said.

China has no public plans for a human mission to the moon, but scientists have said they are studying the possibility of manned expeditions in the future.


quinta-feira, 12 de dezembro de 2013

Meteorite hunter, NASA scientists scour Tucson for fragments

TUCSON - Meteor hunters and assorted scientists are scouring Tucson looking for fragments of a meteor that crashed into the atmosphere Tuesday night.

The large meteor entered the atmosphere over Phoenix and broke up over Marana just after 7 p.m., meteorite hunter Robert Ward said.

Here's YouTube video from Phoenix of the event:
News 4 is joining Ward and other scientists in their search for the meteorite fragments today. They're searching the northwest part of town for its remnants.
Ward joins a team from NASA and the American Meteor Society in their quest.

The American Meteor Society's website has registered 34 eyewitness reports of the fireball so far. People have logged observations from Durango, Santa Fe and Las Vegas.


domingo, 8 de dezembro de 2013

St Martin’s pupils’ close encounter with 4.3 billion year old meteorite, moon samples and rock from Mars

SCHOOL children were given the chance to hold in their hands a 4.3 billion year old fragment of a shooting star.

The truly amazing lump of rock is almost as old as the solar system and nearly a third the age of the entire universe.

The children also handled other meteorites, including one rock from the surface of Mars and samples brought back from the moon by the Apollo astronauts.

The collection came to St Martin Primary School on the Lizard last week after teacher Marcus Conrad applied for a visit on the internet.

“The pupils’ topic this term is time travel and we were looking at travelling into space,” he said.

“I found out about the collection online and applied to have the samples come to school.

“The moon samples are really small and encased in resin. The meteorites are larger and possibly more impressive.

“One of the meteorites is about the size of an orange but really heavy.

“It is quite amazing - it amazes me. I was as excited as the children were at handling these incredible samples.

“I also managed to get some footage of the Apollo landings and I set up a presentation so the children could see directly where the lunar samples came from.”

The moon rock samples, provided by the UK’s Science and Technology Facilities Council (STFC), were collected in the late 1960s and early 1970s during some of NASA’s first manned space missions to the Moon.

A massive 382kg of lunar material was brought back to Earth, mostly for use by scientists, but small quantities are used to develop lunar and planetary sciences packs.

The Martian rock is 1.2 billion years old. It could have been blasted off into space by a meteor impact on Mars before travelling millions of miles to fall to Earth as a shooting star.

Other meteorites in the collection came from the main asteroid belt between Mars and Jupiter.

STFC’s chief executive officer, Professor John Womersley said: “This is a great opportunity for young people to be able to see, touch and really experience such important and exciting messengers from space - turning science fiction into science fact.

“It’s an unforgettable experience to be able to hold such an important part of science history that has made such an incredible journey to reach us. We hope it will inspire the scientists of the future.”


quinta-feira, 5 de dezembro de 2013

Scientist discovers ancient crust from Mars

Using measurements as small as a soil sample from a meteorite, Florida State University researchers led by Dr. Munir Humayun, a professor in the university’s Department of Earth, Ocean and Atmospheric Science, has discovered and began testing what is considered the first example of ancient crust from Mars.

Dated to be about 4.5 billion years old, the rock, named NWA 7533, is believed to hold valuable information regarding Mars’ crust. This rock from a crater was found by a group of Bedouin tribesmen in the Sahara Desert.

“The Bedouin tribesmen of the Sahara desert roam the desert freely and are intimately acquainted with the rocks and minerals of their dry environment,” Humayun said. “In the past three decades they have discovered a market for meteorites with U.S. and European private collectors who pay handsomely for the haul of treasure brought to Moroccan dealers. I don’t know all the details, but the famed meteorite, nicknamed Black Beauty, was purchased from a dealer in Erfoud, Morocco. The dealer had as many as five stones all from the same fall totaling about one and a half kilograms (about three pounds) that were found scattered across the desert floor.”

With this rock now in the possession of FSU researchers, they are looking forward to gaining new insight into the crust of the Red Planet in the scientific community.

“To a geochemist, rocks are like books that are read with a laser to tell their complex stories. This meteorite is like a book with thousands of pages. It told us that the crust of Mars was assembled very early in the planet’s history. Since the crust-building volcanoes burp out water vapor and other gases that form the atmosphere, oceans and earliest life, this is very significant,” Humayun said. “It lends support to the idea of a warm, wet early Mars. We also found Martian soil lumps in the meteorite identical in composition to that measured by spacecraft and rovers at Gusev Crater on Mars. There was only one set of properties that modern Martian soils and these ancient soil lumps did not share.”

If there was an early Martian biosphere, then this rock was likely to have witnessed the microbes.

Humayun’s team includes FSU undergraduate and graduate students. He involves them in various aspects of his research spanning both terrestrial and extra-terrestrial geochemistry. He spends his time teaching both undergraduate and graduate courses, mentoring Ph.D and master’s degree students, and postdoctoral fellows. His research is conducted at the National High Magnetic Field Laboratory, which he says is the best place he has “ever worked in terms of infrastructure support and a wonderful staff.”

“I came to FSU ten years ago as an associate professor because of the excellent geochemical group at the National High Magnetic Field Laboratory. Prior to that I taught at The University of Chicago, where I received the Quantrell Award for Excellence in Undergraduate Teaching,” Humayun said. “I started in Geochemistry with an interest to combine my skills in chemistry, and my interests in nuclear physics with Earth and Space Science. There were excellent Geochemistry facilities and very competent faculty in that area by which I was drawn to Geochemistry.”

With students, faculty and researchers ready to study this rock, they are beginning to uncover important new information about Mars’ ancient crust.

“Importantly, Mars’ surface is covered with two very distinct types of crust: the southern highlands are heavily cratered and therefore very ancient, the northern plains are smooth and have many fewer craters,” Humayun said. “Craters are like wrinkles on people - the more they have the older they appear. A heavily cratered landscape is covered with a rock type known as a breccia–a mixture of many broken fragments of rocks from the repeated hammering by meteorites. These rocks should contain high levels of the element iridium and other elements like it from the meteorite hammers that pounded the ancient Martian surface. This is exactly what we found when analyzing this unusual meteorite. It was a breccia and it was loaded with meteoritic debris containing iridium and nickel.”

Some findings by Humayun and his group are potentially turning what some scientists and researchers thought they knew about the ancient Martian crust upside down.

“Many researchers have long thought that Mars was once intensely melted by large impacts. Our data is inconsistent with this idea termed a magma ocean,” Humayun said. “Evidence for past magma oceans have been found on the Moon, and inferred on Earth, Mars and Mercury, and likely on all major bodies in the inner solar system. Our data on this Martian meteorite, one so ancient it should bear witness to the magma ocean, implicates a cooler growth of Mars, sufficient to melt slightly but no single, large impact sufficient to melt the entire surface of the planet. The idea has strong adherents but our work may change minds.”

Another surprising finding is that using this rock from the meteorite, the rock was able to be dated and found to be a part of the crust that formed around the same time as the crust of the moon and Earth.

“The ages of the zircon minerals in this piece of Martian crust are as old as the oldest zircons recorded from the Earth and Moon,” Humayun said. “What’s surprising is how many such old zircons were found in this Martian meteorite compared with zircons from the Moon and Earth of equal antiquity which are harder to find (and we have so many more rocks from these bodies that have been searched). This implies that Mars’ crust developed very early and that the southern highlands have not been significantly changed over the eons of geological time.”

Humayun and other FSU researchers are making positive steps in discovering information on the origin and age of the ancient Martian crust, and are continuing to find out as much as they can about the Red Planet.