First visit to Bennu in billions of years

An asteroid that may hold the key to life is getting its first visitor in billions of years.

Asteroid Bennu, a black roundish rock taller than the Empire State Building, is the intended target of a NASA spacecraft set to blast off on Thursday night. Not only will the robotic probe named Osiris-Rex fly to this ancient asteroid, it will scout it out for two years before scooping up some gravel and dust, and deliver the samples back to Earth.

All told, the mission will take seven years, from launch to sample return.

Flying to another world is no simple matter. Neither is vacuuming samples off an asteroid. "We're going out into the unknown,'' said principal scientist Dante Lauretta of the University of Arizona at Tucson.

The probe is scheduled to arrive at Bennu in August 2018. For months it will hang out - take pictures, make scans of the asteroid's surface and create a map.

"We're going to get to asteroid Bennu and we're going to map this brand new world that we've never seen before," said Dante Lauretta, the mission's principal investigator.