NASA spacecraft delivering biggest sample yet from an asteroid

bennu asteroid

Planet Earth is about to receive a special delivery - the biggest sample yet from an asteroid.

A NASA spacecraft will fly by Earth on Sunday and drop off what is expected to be at least a cupful of rubble it grabbed from the asteroid Bennu, closing out a seven-year quest.

The sample capsule will parachute into the Utah desert as its mothership, the Osiris-Rex spacecraft, zooms off for an encounter with another asteroid.

A set of Canadian-built lasers helped guide the craft and create a detailed map of the asteroid. 

Scientists anticipate getting about a half pound (250 grams) of pebbles and dust, much more than the teaspoon or so brought back by Japan from two other asteroids.

This is NASA's third sample return from deep space, not counting the hundreds of pounds of moon rocks gathered by the Apollo astronauts.

The agency's first robotic sample grab ended in 2004.