CAPE CANAVERAL, Fla. (AP) — The world is safe — at least from one asteroid.
A 150-foot cosmic rock hurtled safely past Earth on Friday.
It was the closest known flyby for a rock of its size, passing within 17,000 miles. That’s closer than some satellites.
The flyby occurred just hours after a much smaller meteor exploded above Russia’s Ural Mountains.
As asteroids go, DA14 is a shrimp. The one that wiped out the dinosaurs 65 million years ago was 6 miles across. But this rock could still do immense damage if it struck given its 143,000-ton heft, releasing the energy equivalent of 2.4 million tons of TNT and wiping out 750 square miles.
By comparison, NASA estimated that the meteor over Russia was about 15 meters (49 feet) wide and weighed about 7,000 tons before it hit the atmosphere. It was about one-quarter the size of the passing asteroid.
As for the back-to-back events, “this is indeed very rare and it is historic,” said Jim Green, NASA’s director of planetary science. While DA14 is about half the length of a football field, the exploding meteor “is probably about on the 15-yard line,” he said.
“Now that’s pretty big. That’s typically a couple times bigger than the normal influx of meteorites that create these fireballs,” he said in an interview on NASA TV. “These fireballs happen about once a day or so, but we just don’t see them because many of them fall over the ocean or in remote areas. This one was an exception.”
Even after Friday’s scare, scientists remained certain that asteroid DA14 would not impact Earth. And chances were extremely remote, they said, that it will run into any of the satellites orbiting 22,300 miles up.
Most of the solar system’s asteroids are situated in a belt between the orbits of Mars and Jupiter, and remain stable there for billions of years. Some occasionally pop out, though, into Earth’s neighborhood.
The flyby provides a rare learning opportunity for scientists eager to keep future asteroids at bay — and a prime-time advertisement for those anxious to step up preventive measures.
Friday’s meteor — just 16 hours in advance of DA14′s point of closest encounter — further strengthened the asteroid-alert message.
“We are in a shooting gallery and this is graphic evidence of it,” said former Apollo astronaut Rusty Schweickart, chairman emeritus of the B612 Foundation, committed to protecting Earth from dangerous asteroids.
Schweickart noted that 500,000 to 1 million sizable near-Earth objects — asteroids or comets — are out there. Yet less than 1 percent — fewer than 10,000 — have been inventoried.
Humanity has to do better, he said. The foundation is working to build and launch an infrared space telescope to find and track threatening asteroids.
DA14 — discovered by Spanish astronomers last February — is “such a close call” that it is a “celestial torpedo across the bow of spaceship Earth,” Schweickart said in a phone interview Thursday.
The asteroid was invisible to astronomers in the United States at the time of its closest approach on the opposite of the world. But in Australia, astronomers used binoculars and telescopes to watch the point of light speed across the clear night sky.
If a killer asteroid was, indeed, incoming, a spacecraft could, in theory, be launched to nudge the asteroid out of Earth’s way, changing its speed and the point of intersection. A second spacecraft would make a slight alteration in the path of the asteroid and ensure it never intersects with the planet again, Schweickart said.
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