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Friday, February 8, 2013 - Page updated at 07:00 p.m.

Asteroid gives Earth a 'shot across our bow'

By Brian Vastag
The Washington Post

WASHINGTON — A close encounter of the rocky kind is set for Feb. 15, when an office-building-size asteroid will speed past the Earth faster than a bullet and closer than some communications and GPS satellites.

It will be the nearest recorded brush with a space rock so large, NASA scientists said Thursday.

The good news: There’s no chance of an impact. At its closest, asteroid 2012 DA14 will pass 17,000 miles above Earth.

The bad news: A million other potentially dangerous — and unknown — city-killing space rocks are out there, and one could be on a collision course with Earth. Critics say NASA and other space agencies are not doing enough to scan for these threats.

“It’s like Mother Nature sending a warning shot across our bow,” said Don Yeomans, who tracks asteroids for the Jet Propulsion Laboratory in Pasadena, Calif.

Satellite operators said they expected the asteroid to safely cruise through a belt of satellites some 23,000 miles up.

“We’re watching the situation, but there’s not a giant concern,” said Alex Horwitz, spokesman for Intelsat, which operates some 50 communications satellites.

The Air Force is leaving the tracking to NASA.

An astronomer in Spain spied the asteroid a year ago. Small, dim and speedy, it was a “slippery target” as it moved across a background of stars, said Jaime Nomen of the La Sagra Observatory in southern Spain.

NASA-funded scientists then ran the numbers: The asteroid was about 150 feet wide. Its closest approach will occur at 11:24 a.m. PST on the 15th. On the night side of the planet — mainly Asia and Australia — observers with small telescopes might see a pinpoint streaking at the rapid clip of two moon-widths per minute.

Further observations refined the asteroid’s path. It cruises around the sun in an orbit similar to Earth’s. Our year is 365 days. Its year is a day longer. Like a drunken driver weaving across lanes, asteroid 2012 DA14 crosses paths with Earth twice a year at varying distances.

Despite these opportunities for disaster, scientists tracking the asteroid are confident 2012 DA14 won’t collide with us for at least the next century, which is as far as they’ve been able to project its path. Next week’s approach is the closest during that time.

NASA began rigorously scanning the sky for cosmic hazards only in 1998, when Congress told it to. Agency scientists said Thursday they are confident their network of ground and space telescopes has found at least 95 percent of potentially planet-killing asteroids, those a half-mile wide or more. None of these monsters is headed toward Earth, Yeomans said.

But the agency has done much worse identifying smaller threats, said Ed Lu, a former NASA astronaut. Lu spearheads the B612 Foundation, which last year began raising private money to build an asteroid-spotting space telescope.

“Saying we’re only going to find the civilization-killers is a crappy threshold,” Lu said. “We can do better than that.”

An asteroid the size of 2012 DA14 could wipe out a city, Yeomans said.

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