NASA about to land a craft on an asteroid that might hit Earth

NASA scientists want to know more about the beginnings of our universe and the origin of life, and they plan to learn it by landing a craft on an asteroid - and bringing it back.

The asteroid they've got their sights on is called Bennu.

"This is a golden age for planetary exploration," says NASA chief scientist James Green.

"Missions like this will bring in an enormous amount of new information that really is going to tell us about the origin and evolution of life."

The OSIRIS-REx spacecraft launched two years ago, and will reach the asteroid in December. Its mission is to get close enough to briefly touch Bennu's surface and collect dust and soil samples, before flying back to Earth.

Dr Green says those samples could unlock the secrets of our planet's beginnings.

"This mission is all about finding how materials, objects like this, fit in with the origin of the Earth and potentially how it may have started life here on Earth."

Scientists also believe Bennu - which predates Earth - could have traces of water on it.

They also hope to find out whether there's any truth to suggestions it could one day smack into our planet. Current calculations put it at a fraction of a percent, but you can never be too sure.

"By studying it and seeing how it orbits the sun, that will be our clue as to how this asteroid will evolve over time and whether will become a hazard or not."

Bennu's about 500m across, and travelling at 28km a second.

How big the crater might be if Bennu hit Auckland.
How big the crater might be if Bennu hit Auckland. Photo credit: Google Maps/Impact Calculator/Newshub.

If it hit Earth, according to website Impact Calculator it could strike with the force of a magnitude 7 or 8 earthquake, leaving a crater 450m deep and about the size of the Auckland CBD.

"We're not talking about an asteroid that could destroy the Earth," OSIRIS-REx principal investigator Dante Lauretta said prior to the probe's launch. "We're not anywhere near that kind of energy for an impact."

His analysis determined whilst it certainly would be doomsday for those within 50km of the impact site, a few hundred kilometres away people would only notice an earthquake "similar to that of a passing truck", and there might be some loud wind and dust.

OSIRIS-REx is expected to land on Bennu in July 2020, but the asteroid samples won't make it back to Earth until September 2023.

CBS News / Newshub.