The Stanly News and Press (Albemarle, NC)

State & National News

November 8, 2013

Hazardous asteroids may be more numerous than previously thought, scientists say

Friday, November 8, 2013 — There are scads of building-size, potentially hazardous asteroids lurking in Earth's immediate neighborhood, and they may be colliding with the planet 10 times more often than scientists have previously believed, according to a new study published Wednesday that examined the airburst of a 25-million-pound asteroid earlier this year near the Russian city of Chelyabinsk.

Three studies released Wednesday, two in the journal Nature and one in the journal Science, have provided the most detailed description and analysis of the dramatic event on the morning of Feb. 15.

Scientists now estimate the diameter of the object at just a hair under 20 meters, or about 65 feet. Undetected by astronomers, the rock came out of the glare of the sun and hit the atmosphere at 43,000 miles per hour.

As it descended through the atmosphere, it broke into fragments, creating a series of explosions with the combined energy of about 500 kilotons of TNT, making it more than 30 times more powerful than the atom bomb that destroyed Hiroshima in 1945, although the energy in this case was spread out over a much broader area.

The shock wave blew out windows in nearly half the buildings in Chelyabinsk. It knocked people off their feet; dozens were sunburned by the blinding flash, which at its peak was 30 times brighter than the sun. About 1,200 people were hurt, most by broken and flying glass, but no one was killed.

One chunk the size of love seat landed in frozen Chebarkul Lake, leaving a circular hole, as if shot with a bullet from space. That fragment, which weighed about 1,900 pounds, was retrieved months later, breaking into several pieces in the process. Thousands of smaller pieces have also been recovered.

The scientific investigation relied to a great degree on video imagery obtained by "dashcams," the cameras Russian drivers often use to document car crashes and potentially abusive law enforcement. Scientists visited 10 locations where the footage had been taken by stationary cameras, and used landmarks to create a map of the asteroid's trajectory. The shock wave damage propagated perpendicularly to the path of the rock.

"It's incredible how well-documented all this is," said Peter Jenniskens, a meteor astronomer at the SETI Institute and a co-author of the paper in Science.

Taken together, the new information on Chelyabinsk does not suggest that the sky is falling (no one has ever been killed by an asteroid in all of recorded human history). But it may shift the overall risk profile of asteroids, making Chelyabinsk-size events look more probable.

That's the conclusion of Peter Brown, a professor at Western University in London, Ontario, who reexamined decades of data compiled by scientific and military sensors. The scientific orthodoxy said that a Chelyabinsk-size event ought to happen every 140 years or so, but Brown saw several such events in the historical record.

Famously, a large object exploded over the Tunguska region of Siberia in 1908. But there have been less-heralded impacts, including one on Aug. 3, 1963, when an asteroid created a powerful airburst off the coast of South Africa.

"Any one of these taken separately I think you can dismiss as a one-off. But now when we look at it as a whole, over a hundred years, we see these large impactors more frequently than we would expect," said Brown, whose paper appeared in Nature.

Most rocks that size have yet to be identified, and it would be difficult and expensive to find them and calculate their trajectories, Brown said. But this could boost efforts already underway to create early-warning systems for Chelyabinsk-class impactors that are just a few days away, he said.

The paper in Science hypothesized that the Chelyabinsk asteroid is a piece of "rubble" from a larger body that had been broken apart by tidal forces from an earlier near-Earth encounter.

"The rest of that rubble could still be part of the near-Earth object population," the authors wrote.

 

1
Text Only
State & National News
  • Winter created urge to get out of town

    This year's harsh winter contributed to an exodus of travelers seeking refuge from the weather by booking tours, cruises and hotels in record numbers, according to AAA Carolinas Travel Agency. Trips taken by those booking through AAA, the largest leisure travel agency in the Carolinas, showed an increase in tours (15 percent), cruises (12 percent) and hotels (33 percent) over the first quarter of 2013.

    April 22, 2014

  • NCSU Study: The Trials of the Cherokee Were Reflected In Their Skulls

    Researchers from North Carolina State University and the University of Tennessee have found that environmental stressors – from the Trail of Tears to the Civil War – led to significant changes in the shape of skulls in the eastern and western bands of the Cherokee people. The findings highlight the role of environmental factors in shaping our physical characteristics.

    April 22, 2014

  • Do your genes make you procrastinate?

    NEW YORK - Procrastinators, in my experience, like nothing better than explaining away their procrastination: General busyness, fear of failure, and simple laziness are just a handful of the excuses and theories often tossed around. Now researchers from the University of Colorado Boulder have added another option to the list: genetics.

    April 22, 2014

  • NCSU STUDY: Impurity Size Affects Performance of Emerging Superconductive Material

    Research from North Carolina State University finds that impurities can hurt performance – or possibly provide benefits – in a key superconductive material that is expected to find use in a host of applications, including future particle colliders. The size of the impurities determines whether they help or hinder the material’s performance.

    April 22, 2014

  • U.S. Archivist to Speak at NC State Commencement

    David S. Ferriero, archivist of the United States, will deliver NC State’s commencement address on Saturday, May 10, at 9 a.m. at the PNC Center in Raleigh.

    April 22, 2014

  • Smartphone kill switches are coming

    Smartphones need kill switches. It's a relatively easy solution to the pricey (and irritating) problem of smartphone theft. But who would have thought that the big carriers would team up with Apple, Google, Microsoft, Nokia, Samsung and lots of other manufacturers to voluntarily begin adding the technology by July 2015? The cooperative spirit! It makes so much sense!

    April 20, 2014

  • Low blood-sugar levels make for grousing spouses

    Husbands and wives reported being most unhappy with their spouses when their blood-sugar levels were lowest, usually at night, according to research released this week in the Proceedings of the National Academy of Sciences. Missing a meal, dieting or just being hungry may be the reason, researchers said.

    April 20, 2014

  • Consumer spending on health care jumps as Affordable Care Act takes hold

    WASHINGTON - Nancy Beigel has known since September that she would need hernia surgery. She couldn't afford it on her $11,000 yearly income until she became eligible for Medicaid in January through President Barack Obama's signature health care law.

    April 19, 2014

  • Why Facebook is getting into the banking game

    Who would want to use Facebook as a bank? That's the question that immediately arises from news that the social network intends to get into the electronic money business.

    April 15, 2014

  • E-Cigarettes target youth with festivals, lawmakers say

    WASHINGTON - The findings, in a survey released Monday by members of Congress, should prod U.S. regulators to curb the industry, the lawmakers said. While e-cigarettes currently are unregulated, the Food and Drug Administration is working on a plan that would extend its tobacco oversight to the products.

    April 15, 2014

House Ads
Seasonal Content