Close Encounter by Asteroids Makes Case for Scrutiny
The twin punch of a meteor raining destruction on remote Russia and an asteroid hurtling past Earth prompted calls from scientists and political leaders for greater vigilance to combat risks from the heavens.
The meteor exploded yesterday over Russia’s Chelyabinsk region in the Ural Mountains, causing shock waves that shattered windows over 50 acres and injured 1,200 residents. The meteor struck 16 hours before an asteroid half the size of a U.S. football field flew within 17,200 miles of Earth, the closest such pass of a body that size in a century.
“It appears to be a cosmic coincidence,” Mark Hammergren, an astronomer at Chicago’s Adler Planetarium, said in an interview. “Both of these things are reminding us that we live on a dynamic Earth. There are a lot of things going on in the universe.”
For astronomers, space agencies and officials, that coincidence points to the need to increase vigilance of space objects. While NASA, the European Space Agency and other bodies track the largest asteroids -- and assess their risks -- smaller objects such as the Russian meteorite are largely undetected.
Meteors similar in size to the Russian object, which may have weighed 100 tons, reach Earth’s atmosphere on average every few decades. They usually fall in the ocean, deserts or far from population centers, said Jay Melosh, a professor in the atmospheric sciences department at Purdue University in West Lafayette, Indiana.
“The Russians got very unlucky,” he said.
The biggest risk may be that governments will deem their nation is being attacked by a bomb or a missile, and launch a strike against an imaginary aggressor.
“People need to realize that there are times when the sky will fall on you,” K.T. Ramesh, director of the Johns Hopkins University (43935MF) Extreme Materials Institute, said in an interview. Government retaliation may be “the biggest risk for us. We are able to destroy ourselves very comfortably.”
While DA14 didn’t hit the planet, astronauts and interplanetary evangelists say its fly-by -- and the meteor strike in Russia -- serve as evidence that an asteroid may hit Earth one day.
An asteroid the size of DA14 slammed into rural Russia in 1908 and leveled millions of trees over 820 square miles. The asteroid scientists say plowed into Earth about 66 million years ago, wiping out the dinosaurs, was about 6 miles in diameter.
“Fortunately for us, there are many more smaller cosmic debris in space than larger, mountain-size objects,” Supriya Chakrabarti, a professor at the University of Massachusetts at Lowell, said in an e-mail. “Most of them burn up in the atmosphere and do not have any impact on everyday life.”
A United Nations “Action Team” met in Vienna this week to come up with recommendations on how best to track -- and some day deflect or destroy -- these orbiting space rocks.
“The goal is that we can see objects this size about two days before they hit the Earth,” said Detlef Koschny, a scientist at the European Space Agency, referring to the Russian meteor. An ESA project aims to detect every object about to hit the earth, no matter what size.
“Then we can decide in each case: If it is just one meter, you could watch the spectacle,” he said. “If it’s bigger than five meters, you should step away from the window because the pressure might destroy it.”
Individual governments are reacting as well. The U.S. House Committee on Space, Science and Technology said it will hold a hearing on “asteroids that pose a potential threat to Earth” in the coming weeks. Russia will push ahead with efforts to “shoot down objects of alien origin,” Deputy Prime Minister Dmitry Rogozin said on Twitter.
In 1998, the U.S. space agency NASA began working on finding and tracking the largest asteroids, typically more than one kilometer in diameter and capable of destroying much of humanity. That’s left a gap in finding smaller objects that would demolish a city while sparing the rest of civilization.
NASA says it has found and mapped 1,310 of the largest, most dangerous “near-Earth objects.” The total may account for less than 10 percent of all nearby space bodies, it says.
Finding asteroids is not just about danger, it’s also about research. NASA is preparing to launch a probe to a nearby asteroid in 2016 to study its orbit and composition. Observatories worldwide were on alert yesterday to look for clues about the makeup, size and rotation of DA14.
The probability of an asteroid causing widespread destruction on Earth is fairly low. An asteroid on a collision course could possibly be deflected with a spacecraft, redirected with a “gravity tractor” hovering nearby or, as a last resort, targeted with a nuclear explosion.
“If we’re lucky, none of us will see an asteroid coming toward the Earth in our lifetime,” Sergio Camacho, the head of the UN’s effort on near-earth objects, said in an interview. “But if we’re not lucky and we didn’t do anything, the only thing we might be able to do is evacuate.”
“This alone could be a disastrous event.”
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