Building blocks of life discovered in dust and soil from asteroid Bennu

Nasa said that the findings do not show evidence for life itself, but they do suggest the conditions necessary for the emergence of life were widespread across the early solar system.

In Short

• The samples were retrieved by Nasa's OSIRIS-REx spacecraft
• Asteroids provide a time capsule into our home planet’s history
• Two analyses of the samples were published

Scientists have discovered chemical building blocks of life in rocks and soil samples from asteroid Bennu.

The samples are some of the best evidence to date that such space rocks may have seeded early Earth with the raw ingredients that fostered the emergence of living organisms.

The samples, retrieved by Nasa's Origins, Spectral Interpretation, Resource Identification and Security-Regolith Explorer (OSIRIS-REx) spacecraft, revealed the presence of not just molecules that, on our planet, are key to life, but also traces of saltwater.

Nasa said that the findings do not show evidence for life itself, but they do suggest the conditions necessary for the emergence of life were widespread across the early solar system.

“NASA’s OSIRIS-REx mission already is rewriting the textbook on what we understand about the beginnings of our solar system. Asteroids provide a time capsule into our home planet’s history, and Bennu’s samples are pivotal in our understanding of what ingredients in our solar system existed before life started on Earth,” Nicky Fox, associate administrator, Science Mission at Nasa said.

Two analyses of the samples were published on Wednesday.

One, in the journal Nature Astronomy, found that the samples contained a diverse mixture of organic compounds, and the other, in the journal Nature found that the samples contained minerals formed when brine - salty water - evaporated on Bennu's parent body, the type of wet environment where prebiotic organic chemistry may have brewed.

In the early solar system, planets including Earth and various moons were pelted by asteroids and other space debris that carried water and chemicals including organic compounds.

Organic compounds have one or more carbon atoms that are bound to other elements, usually hydrogen, oxygen, nitrogen and sulfur. All life on Earth is based on carbon and is built from organic compounds including the amino acids used to create proteins and nucleobases.

A nucleobase is a nitrogen-containing compound that stores genetic information. DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are biomolecular cousins that are fundamental molecules in cell biology. DNA contains an organism's genetic code.

Scientists also described exceptionally high abundances of ammonia in the Bennu samples. Ammonia is important to biology because it can react with formaldehyde, which also was detected in the samples, to form complex molecules, such as amino acids

These building blocks for life detected in the Bennu samples have been found before in extraterrestrial rocks.