NASA probe nears distant space rock for landmark flyby  

At 12:33 a.m. Eastern time (0533 GMT), the New Horizons probe will arrive at the "third zone" in the uncharted heart of the Kuiper Belt, scientists said.In this peripheral layer of icy bodies and leftover fragments from the solar system's creation, the interplanetary probe will position its seven on-board instruments for the first close-up glance of Ultima Thule, a cool mass roughly 20 miles (32 km) long and shaped like a giant peanut.Scientists had not discovered Ultima Thule when the probe was