US spacecraft diving to asteroid for rare rubble grab

CAPE CANAVERAL, Fla. (AP) — A NASA spacecraft descended Tuesday toward the surface of an asteroid 200 million miles away to collect a handful of rubble for return to Earth.

The Osiris-Rex spacecraft dropped out of orbit around asteroid Bennu right on time, beginning a 4 1/2-hour plunge to the rough, boulder-covered face of the ancient space rock.

It was America's first attempt to gather samples from an asteroid, something already accomplished by Japan — twice.

Bennu’s gravity was too low for the spacecraft to land — the asteroid is just 1,670 feet (510 meters) across. As a result, Osiris-Rex has to reach out with its 11-foot (3.4-meter) robot arm while dodging boulders the size of buildings, and attempt to grab at least 2 ounces (60 grams) of Bennu.

It promised to be the most harrowing part of the mission, which began with a launch from Cape Canaveral back in 2016.

"We’ll only be kissing the surface with a short touch-and-go measured in just seconds,” said the University of Arizona's Heather Enos, the deputy scientist for the mission.

A van-sized spacecraft with an Egyptian-inspired name, Osiris-Rex aimed for a spot equivalent to a few parking spaces on Earth in the middle of the asteroid's Nightingale Crater. After nearly two years orbiting Bennu, the spacecraft found this location to have the biggest patch of particles small enough to be swallowed up.

The plan called for Osiris-Rex to shoot out pressurized nitrogen gas to stir up the surface, then suck up any loose pebbles or dust. Contact was expected to last a mere 5 seconds to 10 seconds, with the spacecraft quickly backing away.

NASA won’t know until later this week how much was actually collected — or whether the spacecraft got anything at all.

Unlike the exceptionally fast Mars descents —...