Asteroid Bennu sample proves humans are, in fact, made of stardust: Study

Scientists have detected organic compounds and minerals necessary for life in samples from asteroid Bennu. This discovery offers compelling evidence that all life on Earth, including humans, is likely made of stardust, and asteroids delivered the so-called building blocks of life to our planet Earth millions of years ago.

These amazing findings not only provide proof about the chemical processes that took place in the primordial solar system, but also raise new questions about the potential for life elsewhere in the cosmos.

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'Exciting' discovery

"This is all very exciting because it suggests that asteroids like Bennu once acted like giant chemical factories in space and could have also delivered the raw ingredients for life to Earth and other bodies in our solar system," said Dr Daniel P Glavin, senior scientist for samples return at NASA's Goddard Space Flight Center, as cited by CNN.

Glavin, the lead author of the study published Wednesday in the journal Nature Astronomy, revealed that his team of scientists found building blocks of life, such as amino acids and even components found in DNA in the asteroid samples.

A separate paper, also published Wednesday in the journal Nature, also uncovered salts and minerals crucial to life, including some never seen in asteroid samples before, within Bennu’s rocks.

Results of both the papers were shared during a NASA press conference on Wednesday, where they were labelled "groundbreaking scientific discovery," by Nicky Fox, associate administrator for NASA’s Science Mission Directorate.

Historic sample collection

These historic samples were collected by NASA's OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification and Security-Regolith Explorer) mission in October 2020.

It was the first time that the US sent a spacecraft to briefly land on the near-Earth asteroid and collect a sample, which was then distributed among scientists from across the world.

The samples are the first pristine material retrieved from an asteroid by the US. Rigorous precautions ensured that the samples were uncontaminated by Earth's environment, preserving their extraterrestrial integrity.

Key discoveries in Bennu's composition

Scientists have identified a rich array of organic molecules, including 33 amino acids, essential for building proteins, and all five nucleobases found in DNA and RNA—adenine, guanine, cytosine, thymine, and uracil.

What makes the discovery even more special is that unlike meteorites, which are exposed to heat and Earth's atmosphere upon entry, Bennu's samples are pristine. This provides stronger evidence that the building blocks of life found on the asteroid were formed in space.

Bennu's samples also contained minerals such as sodium phosphates, carbonates, and sulfates, along with traces of ancient water locked within the asteroid's crystalline structures. These elements, particularly ammonia and nitrogen-rich compounds.

Scientists believed that Bennu originated from a larger parent asteroid, formed about 4.5 billion years ago in the solar system's cold outer regions. Their analyses have revealed that water once flowed within Bennu's parent body, leaving behind brine pockets rich in salts and minerals. These environments may have created conditions for complex organic molecules to form. Sodium carbonate, a mineral never before seen in asteroid samples was also detected, which points to processes similar to those on Earth's dry lakebeds.

(With inputs from agencies)