The exploration of asteroid Bennu has yielded astonishing discoveries that could reshape our understanding of life's origins on Earth. Samples collected by NASA's Osiris Rex spacecraft reveal that the grainy dust of the 500m-wide asteroid contains a treasure trove of chemicals essential to life, including amino acids and nucleobases—the building blocks of proteins and DNA, respectively.
While this does not imply that life ever existed on Bennu itself, it reinforces the hypothesis that asteroids may have been responsible for delivering the fundamental ingredients for life to our planet during its formative years. “What we've learned from it is amazing,” stated Prof. Sara Russell, a cosmic mineralogist from the Natural History Museum in London. She emphasized the significance of these findings in answering deep existential questions about the origins of life.
The findings have been documented in two recent studies published in the journal Nature. NASA's ambitious mission to grab a sample from Bennu culminated in 2023 when the Osiris Rex spacecraft successfully gathered approximately 120g of the asteroid's black dust. Despite the small quantity, this sample is rich in information, suggesting that every grain reveals new insights about the asteroid’s past.
Advanced imaging techniques disclosed that Bennu is abundant in nitrogen and carbon-rich compounds. Impressively, researchers identified 14 out of the 20 amino acids crucial for building proteins and all four of the nucleobases that constitute DNA, including adenine and guanine. Additionally, minerals indicating that water was once present on the asteroid have been detected, alongside ammonia essential for biochemical reactions.
Dr. Ashley King from Natural History Museum remarked on the implications of these findings, suggesting that asteroids like Bennu may have acted as cosmic messengers, delivering vital resources across the young Solar System. “Earth is unique, in that it's the only place we have found life so far, but we know asteroids were delivering the ingredients for life,” he explained.
The research offers an exciting avenue for future inquiries; scientists are determined to explore whether similar conditions for life could exist elsewhere in our Solar System, continuing their quest to unravel the mysteries surrounding the genesis of life in the cosmos.
