NASA probe nears distant space rock for landmark flyby

FILE PHOTO: An artist's impression of NASA's New Horizons spacecraft, currently en route to Pluto, is shown in this handout image provided by NASA/JHUAPL. REUTERS/NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Handout/File Photo

ORLANDO, Fla. (Reuters) - A NASA explorer is on track to reach the solar system's outermost region by early Tuesday morning, when scientists expect it to fly by a space rock 20 miles long and billions of miles from Earth, the most distant close encounter of its kind.

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.