A NASA spacecraft has returned asteroid samples that hold not only the pristine building blocks for life but also the salty remains of an ancient water world.

In samples NASA brought back from the asteroid Bennu, scientists have discovered of organic compounds, including key building blocks of life like amino acids.

It took two years for NASA's OSIRIS-REx space probe to return from asteroid Bennu before dropping off a small capsule as it flew past Earth, which was then recovered in the desert of the U.S. state of Utah on September 24,