LAUREL, Md.—The NASA spacecraft that yielded the first close-up views of Pluto hurtled toward a New Year’s Day rendezvous with a tiny, icy world a billion miles farther out, in what would make it the most distant cosmic body ever explored by humankind.
New Horizons was on course to fly past the mysterious, primitive object nicknamed Ultima Thule at 12:33 a.m. on Jan. 1. The close encounter comes 3 1/2 years after the probe’s swing past Pluto, which until now was the farthest object visited by a spacecraft from Earth.
