NASA's OSIRIS-REx spacecraft has returned samples from the asteroid Bennu, providing groundbreaking insights about the origins of life and the water on Earth. The samples, collected from Bennu during the spacecraft's 2020 mission, have revealed a treasure trove of organic compounds and minerals fundamental to biological processes.
The sample analysis, published in prestigious journals such as Nature and Nature Astronomy, highlights significant discoveries from Bennu. Among the findings are 14 of the 20 amino acids necessary for protein formation, as well as all five nucleobases found in DNA and RNA. Key minerals indicative of past water activity, such as evaporite minerals including calcite, halite, and sylvite, suggest conditions previously thought unique to Earth may have also existed on Bennu.
According to NASA's senior sample scientist, Danny Glavin, the pristine state of the Bennu sample allowed researchers to detect compounds unaltered by Earth’s environmental impact, providing unprecedented clarity on the organic chemistry potential hosted within the early solar system. "This is the first time we have detected such organic materials directly from space rather than from meteorites," he stated.
The study's lead, Tim McCoy from the Smithsonian’s National Museum of Natural History, noted, "We have discovered the next step on the pathway to life. The combination of the basic elements with water aspects opens pathways to the development of life as we know it." These findings support the idea of asteroids as carriers of life's building blocks and have far-reaching implications for our knowledge of planetary formation and the conditions under which life could emerge.
The returns from asteroid Bennu have also raised intriguing questions about the nature of amino acids themselves. Project scientist Jason Dworkin pointed out the observation of balanced left- and right-handed molecular orientations of amino acids, contrasting with those predominantly found on Earth. "This data furthers our inquiry about why life has so far only been observed here," Dworkin explained.
Further mineral analysis indicates extensive water activity on Bennu, hinting at liquid brines having existed on its surface. This suggests ancient water bodies may have housed the conditions necessary for the formative steps leading to life. "The salts and minerals found provide clues as to how water and organic material came together," remarked Michelle Thompson, associate professor of earth, atmospheric, and planetary sciences. "Asteroids like Bennu are time capsules offering insights about early solar systems and, potentially, the genesis of life on Earth."
This significant cosmic event not only enhances our comprehension of our own planet's origins but also broadens possibilities for life beyond Earth. The findings from Bennu resonate with theories such as panspermia—the idea of life, or its building blocks, possibly traveling between celestial bodies, through mechanisms such as asteroid impacts.
The sample's composition, which includes traces of minerals rich with nitrogen and ammonia, contributes to our knowledge about the origins of Earth's water. Recognizing whether similar conditions to those on Bennu have existed elsewhere—whether on Mars, the icy moon Europa, or Saturn's moon Enceladus—adds layers of urgency to the scientific exploration of other worlds.
Experts have emphasized the fragility of the terrestrial environment, where organic materials' exposure can lead to contamination. The careful collection and preservation of the Bennu samples circumvented such issues, ensuring the data remain untainted. "This discovery was only possible by analyzing samples collected directly from the asteroid then preserved properly back on Earth," explained Yasuhito Sekine from the Institute of Science Tokyo.
Since the return of the Bennu samples, scientists across the globe have engaged rigorously with this unique research opportunity, analyzing isotopes and studying mineral contents to piece together the history of our solar system. The ultimate objective is to create clearer narratives about how life-supporting environments form and evolve.
Sara Russell, co-lead author of one of the studies, encapsulated the collision of findings: "Even though the asteroid Bennu harors no life itself, the question remains: can other icy bodies host life? The materials from Bennu significantly advance our investigations concerning Earth’s history and the quest for life beyond our planet.” Science continues to bid us more questions than it answers, fostering the curiosity inherent to human nature.