Unlike meteor - asteroid buzzes, misses Earth

This image provided by NASA/JPL-Caltech shows a simulation of asteroid 2012 DA14 approaching from the south as it passes through the Earth-moon system on Friday, Feb. 15, 2013. The 150-foot object will pass within 17,000 miles of the Earth. NASA scientists insist there is absolutely no chance of a collision as it passes. (AP Photo/NASA/JPL-Caltech)

NASA scientists at the Jet Propulsion Laboratory in La Cañada Flintridge said the passage of the space rock - known as 2012 DA 14 - was unrelated to a meteor explosion in Russia just hours earlier.

Even so, it was a close call - so close that 2012 DA 14 flew inside the orbits of many of the satellites that monitor communications and weather here on Earth. Its passage during daylight hours in California, delighted astronomers in Australia and elsewhere who watched it zip harmlessly through a clear night sky.

"It's on its way out,"reported Paul Chodas of NASA's Near-Earth Object program at JPL.

The asteroid was too small to see with the naked eye even at its closest approach around 11:25 a.m. PST, over the Indian Ocean near Sumatra.

The best viewing locations, with binoculars and telescopes, were in Asia, Australia and eastern Europe. Even there, all anyone could see was a pinpoint of light as the asteroid buzzed by at 17,400 mph.

As asteroids go, this one is a shrimp. The one that many believe wiped out the dinosaurs 65 million years ago was 6 miles across. But this rock could still do immense damage if it ever 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 that exploded over Russia was tiny - about 49 feet wide and 7,000 tons before it hit the atmosphere, or one-third 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 the asteroid is about half the length of a football field, the exploding meteor "is probably about on the 15-yard line," he said.

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.

NASA scientists estimate that an object of this size makes a close approach like this every 40 years. The likelihood of a strike is every 1,200 years.

Friday's meteor 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.

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.

Asteroid DA14 - discovered by Spanish astronomers only 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.

NASA's deep-space antenna in the Mojave Desert was ready to collect radar images, but not until eight hours after the closest approach given the United States' poor positioning for the big event.