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 is no chance of an impact. At its closest, asteroid 2012 DA14 will pass 17,000 miles above the earth.
The bad news: A million other potentially dangerous — and unknown — city-killing space rocks are out there, and one of them 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 were monitoring the asteroid but that they expected it 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, meanwhile, 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, and its closest approach will occur at 2:24 p.m. Eastern Standard Time on Friday.