CAPE CANAVERAL, Fla. (AP) -- NASA is using an asteroid's close flyby to test Earth's warning network for incoming space rocks.
The small asteroid will pass within about 27,200 miles (43,800 kilometers) of Antarctica early Thursday.
Program scientist Michael Kelley says that's "pretty close" as these things go. But he stresses there's no chance it will hit us. Future space rocks might, though -- thus this first-of-its-kind cosmic fire drill.
Observatories worldwide have been zooming in on the asteroid called 2012 TC4 for weeks to test communication and coordination. Kelley said Wednesday it's gone well. The exercise will continue for another week, as observatories keep tracking the asteroid as it departs Earth's neighborhood.
The asteroid is estimated to measure 45 feet to 100 feet (14 to 30 meters.)