Potentially dangerous asteroid to fly by Earth on January 26


A potentially hazardous asteroid, at least 20 times the size of the Chelyabinsk meteorite, will approach the Earth on January 26. The rock is expected to fly by at a distance of 1.2 million kilometers.

AFP/NASA

The asteroid, named 2004 BL86 by scientists, is estimated to be between 440-1,000 meters in diameter. 1.2 million kilometers is approximately three times the distance from the Earth to the Moon.

According to astronomers, there is no threat of the object colliding with our planet. The Goldstone Observatory, located in California’s Mojave Desert, will observe the asteroid during its approach.

2004 BL86 was discovered on January 30, 2004, by the Lincoln Near-Earth Asteroid Research (LINEAR), responsible for the majority of asteroid discoveries from 1998 until 2005, when it was overtaken by the Catalina Sky Survey (CSS). As of mid-September 2011, LINEAR had detected some 231,082 new objects, of which at least 2,423 were near-Earth asteroids and 279 comets.

A space object is considered potentially dangerous if it crosses the Earth’s orbit at a distance of less than 0.05 AU (approximately 19.5 distances from the Earth to the Moon), and if its diameter exceeds 100-150 meters. Objects of this size are large enough to cause unprecedented destruction, or generate a mammoth tsunami in case they fall into the ocean.

When a meteorite burst above the city of Chelyabinsk in February 2013, the impact was estimated to be equivalent to 440-500 kilotons of TNT. But the Chelyabinsk meteorite was relatively small, about 17 meters in diameter. It disintegrated with a blast at an altitude of over 20 kilometers.

First study results of Russian Chelyabinsk meteor published.


The meteor that exploded over Chelyabinsk, Russia in February 2013 was “a wake-up call,” according to a University of California, Davis scientist who participated in analyzing the event. The work is published November 7, 2013 in the journal Science by an international team of researchers. “If humanity does not want to go the way of the dinosaurs, we need to study an event like this in detail,” said Qing-Zhu Yin, professor in the Department of Earth and Planetary Sciences at UC Davis.

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Chelyabinsk was the largest meteoroid strike since the Tunguska event of 1908, and thanks to modern technology from consumer video cameras to advanced laboratory techniques, provides an unprecedented opportunity to study such an event, the authors note.

The Chelyabinsk meteorite belongs to the most common type of meteorite, an “ordinary chondrite.” If a catastrophic meteorite strike were to occur in the future, it would most likely be an object of this type, Yin said.

The team was led by Olga Popova of the Russian Academy of Sciences in Moscow, and by NASA Ames and SETI Institute meteor astronomer Peter Jenniskens, and included 57 other researchers from nine countries.

“Our goal was to understand all circumstances that resulted in the damaging shock wave that sent over 1200 people to hospitals in the Chelyabinsk Oblast area that day,” said Jenniskens. The explosion was equivalent to about 600 thousand tons of TNT, 150 times bigger than the 2012 Sutter’s Mill meteorite in California.

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Based on viewing angles from videos of the fireball, the team calculated that the meteoroid entered Earth’s atmosphere at just over 19 kilometers per second, slightly faster than had previously been reported.

“Our meteoroid entry modeling showed that the impact was caused by a 20-meter sized single chunk of rock that efficiently fragmented at 30 km altitude,” Popova said. (A meteoroid is the original object; a meteor is the “shooting star” in the sky; and a meteorite is the object that reaches the ground.)

The meteor’s brightness peaked at an altitude of 29.7 km (18.5 miles) as the object exploded. For nearby observers it briefly appeared brighter than the Sun and caused some severe sunburns.

The team estimated that about three-quarters of the meteoroid evaporated at that point. Most of the rest converted to dust and only a small fraction (4,000 to 6,000 kilograms, or less than 0.05 percent) fell to the ground as meteorites. The dust cloud was so hot it glowed orange.

The largest single piece, weighing about 650 kilograms, was recovered from the bed of Lake Chebarkul in October by a team from Ural Federal University led by Professor Viktor Grokhovsky.

Shockwaves from the airburst broke windows, rattled buildings and even knocked people from their feet. Popova and Jenniskens visited over 50 villages in the area and found that the shockwave caused damage about 90 kilometers (50 miles) on either side of the trajectory. The team showed that the shape of the damaged area could be explained from the fact that the energy was deposited over a range of altitudes.

The object broke up 30 kilometers up under the enormous stress of entering the atmosphere at high speed. The breakup was likely facilitated by abundant “shock veins” that pass through the rock, caused by an impact that occurred hundreds of millions of years ago. These veins would have weakened the original meteoroid.

Yin’s laboratory at UC Davis carried out chemical and isotopic analysis of the meteorites. Professor Ken Verosub, also of the Department of Earth and Planetary Sciences, measured the magnetic properties of metallic grains in the meteorite. Doug Rowland, project scientist in the Center for Molecular and Genomic Imaging at the UC Davis Department of Biomedical Engineering, contributed X-ray computed tomography (CT) scanning of the rock.

Put together, these measurements confirmed that the Chelyabinsk object was an ordinary chondrite, 4,452 million years old, and that it last went through a significant shock event about 115 million years after the formation of the solar system 4,567 million years ago. That impact was at a much later date than in other known chondrites of the same type, Yin said, suggesting a violent history.

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Jenniskens calculated that the object may have come from the Flora asteroid family in the asteroid belt, but the chunk that hit the Chelyabinsk area was apparently not broken up in the asteroid belt itself. Researchers at the University of Tokyo and Waseda University in Japan found that the rock had been exposed to cosmic rays for only about 1.2 million years, unusually short for rocks originating in the Flora family.

Jenniskens speculates that Chelyabinsk belonged to a bigger “rubble pile” asteroid that broke apart 1.2 million years ago, possibly in an earlier close encounter with Earth.

The rest of that rubble could still be around as part of the near-earth asteroid population, Jenniskens said.

Yin noted that major meteorite strikes like Tunguska or Chelyabinsk occur more frequently than we tend to think. For example, four tons of material were recovered from a meteor shower in Jilin, China in 1976.

“Chelyabinsk serves as unique calibration point for high energy events for our future studies,” he said. Technology for early detection of these objects is needed, Yin said—such as the Large Synoptic Survey Telescope, currently being developed by an international team headed by UC Davis physics professor J. Anthony Tyson.

United Nations to Adopt Asteroid Defense Plan.


Earth is not prepared for the threat of hazardous rocks from space, say astronauts who helped formulate the U.N. measures.

Illustration of asteroid impacting earth

When a meteor exploded over Chelyabinsk, Russia in February, the world’s space agencies found out along with the rest of us, on Twitter and YouTube. That, says former astronaut Ed Lu, is unacceptable—and the United Nations agrees. Last week the General Assembly approved a set of measures that Lu and other astronauts have recommended to protect the planet from the dangers of rogue asteroids.

The U.N. plans to set up an “International Asteroid Warning Group” for member nations to share information about potentially hazardous space rocks. If astronomers detect an asteroid that poses a threat to Earth, the U.N.’s Committee on the Peaceful Uses of Outer Space will help coordinate a mission to launch a spacecraftto slam into the object and deflect it from its collision course.

Lu and other members of the Association of Space Explorers (ASE) recommended these steps to the U.N. as a first step to address at the long-neglected problem of errant space rocks.  “No government in the world today has explicitly assigned the responsibility for planetary protection to any of its agencies,” ASE member Rusty Schweickart, who flew on the Apollo 9 mission in 1969, said at the museum. “NASA does not have an explicit responsibility to deflect an asteroid, nor does any other space agency.” The ASE advocates that each nation delegate responsibility for dealing with a potential asteroid impact to an internal agency—before the event is upon us.

The next step in defending Earth against dangerous asteroids is to find them, Lu said. “There are 100 times more asteroids out there than we have found. There are about 1 million asteroids large enough to destroy New York City or larger. Our challenge is to find these asteroids first before they find us.”

Early warning is important because it increases the chance of being able to deflect a threatening asteroid once it is found. If a spacecraft struck an asteroid 5 or 10 years before the rock was due to hit Earth, a slight orbital alternation should be enough to make it pass Earth by; if the asteroid wasn’t detected soon enough, evacuating the impact zone may be the only option available. “If we don’t find it until a year out, make yourself a nice cocktail and go out and watch,” Schweickart quipped.

The B612 Foundation, a non profit Lu founded to address the problem of asteroid impacts, is developing a privately funded infrared space telescope called Sentinel, which it hopes to launch in 2017. The telescope would begin a systematic search for hazardous near-Earth objects.

The ASE astronauts are also asking the United Nations to coordinate a practice asteroid deflection mission to test out the technologies for pushing a rock off course should the need arise. The meteor in Chelyabinsk, which injured 1,000 people but killed none, was an ideal warning shot across the bow, said American Museum of Natural History astronomer Neil deGrasse Tyson, who hosted Friday’s event—now, it’s time for Earth’s citizens to take action.  Lu agreed: “Chelyabinsk was bad luck,” he said. “If we get hit again 20 years from now, that is not bad luck—that’s stupidity.”

Armageddon 2.


Armageddon 2Want to know if that meteor that just struck Earth has a companion? Take a look at its trail. A new study shows that images of a meteor’s streak through the atmosphere taken by Earth-gazing probes, including weather satellites, can pin down the object’s orbit, enabling scientists to check and see whether another planet-threatening object is traveling in the same trajectory. The finding comes thanks to the almost-20-meter-wide meteoroid that blazed into Earth’s atmosphere in February and exploded over Chelyabinsk, Russia, damaging buildings there and injuring hundreds. Soon after it streaked over the country (main image)—in some cases, mere minutes later—a number of satellites snapped views of the trail from on high (example, inset). Analyses of those images enabled researchers to confirm the trail’s location, height, and orientation, which in turn allowed them to determine the orbit that the object had been following before it slammed into the atmosphere. The orbit estimated using satellite data alone reasonably matched the one estimated via ground-based videos, the team reports online today in the Proceedings of the National Academy of Sciences. In situations where objects enter Earth’s atmosphere in more remote locations—over the ocean far from land, for example—satellites may be the only sources of data that could be used to determine an object’s orbit. The threat to our planet from an object’s orbital companions isn’t merely an abstract concern, the researchers contend: One recent study suggests that about 15% of the asteroids that cross Earth’s path may be part of double or triple asteroid systems.

Huge half-ton chunk of Russian meteorite lifted from lakebed.


The largest-discovered fragment of a Russian meteorite, weighing around 570 kilograms, has been lifted from the bed of Lake Chebarkul in the Urals.

The huge meteorite chunk split into three pieces when scientists tried to weigh it. The precise weight could not be established because the heavy object broke the scales. 

The preliminary examination… shows that this is really a fraction of the Chelyabinsk meteorite. It’s got thick burn-off, the rust is clearly seen and it’s got a big number of indents. This chunk is most probably one of the top ten biggest meteorite fragments ever found,” said Sergey Zamozdra, associate professor of Chelyabinsk State University, as cited by Interfax news agency. 

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He explained that it was important to establish the weight of the fragment in order to learn more about the qualities of the whole of the meteorite.

The lifted chunk was taken to the regional natural history museum. The plan is to have a small sample of it X-rayed to determine what minerals it consists of. 

Several earlier attempts to raise this massive chunk of meteorite, found by divers at the beginning of September, failed.

The divers’ mission was hampered by a number of factors. The meteorite fragment lay 20 meters under water, buried under a thick layer of mud.

Estimates concerning the layer of sediments covering the chunk were more optimistic than what the divers actually had to deal with. It took them 10 days to pump the mud away from the rock. 

The divers had to do their job in conditions of zero visibility, due to the extremely muddied waters of the lake. Storms further contributed to delays in lifting the celestial body. 

The largest lifted chunk of meteorite so far weighed 11 kilograms. Scientists on Wednesday confirmed its extraterrestrial nature. 

A huge meteorite, weighing around 11,000 tons, exploded over the Chelyabinsk region in Russia on February 15. It injured more than 1,600 people, and inflicted plenty of damage – around a billion rubles ($31 million) worth and also caused mass media frenzy.

RIA Novosti / Aleksandr Kondratuk

Overall 12 alleged pieces of meteorite have so far been raised from the lakebed.  Five of them were confirmed as meteorite fragments.