Asteroid Bennu Yields Up Life's Building Blocks, Hinting at Widespread Potential for Life in Early Solar System
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| NASA's OSIRIS-REx mission finds crucial organic molecules on asteroid Bennu, hinting at a greater potential for life. Image: NASA |
Washington, USA — January 29, 2025:
A treasure trove of organic molecules, including the essential building blocks of life, has been unearthed in samples returned from asteroid Bennu by NASA's OSIRIS-REx mission. Scientists have confirmed the presence of amino acids, the foundation of proteins, and nucleobases, the core components of DNA and RNA, within the asteroid's rocks and dust. This remarkable discovery suggests that the ingredients for life were prevalent throughout the early solar system, raising the tantalizing possibility that life may have arisen elsewhere.
While the Bennu samples don't contain evidence of existing life, the presence of these key molecules, along with evidence of ancient saltwater on the asteroid, strongly indicates that the conditions necessary for life's emergence were widespread. Researchers also detected ammonia and formaldehyde, which can combine under the right circumstances to form more complex organic compounds, further bolstering this hypothesis.
"OSIRIS-REx has revolutionized our understanding of the solar system's origins," said Nicky Fox, associate administrator of NASA's Science Mission Directorate. "Bennu is a time capsule from our planet's past, and these samples are crucial to deciphering the conditions that existed before life took hold on Earth."
The analysis, detailed in papers published in Nature and Nature Astronomy, reveals 14 of the 20 amino acids crucial for life on Earth, as well as all five nucleobases. The abundance of ammonia is particularly noteworthy, as it plays a vital role in the formation of complex organic molecules.
"These molecules are incredibly fragile and easily altered by Earth's environment," explained Danny Glavin, a senior sample scientist at NASA Goddard Space Flight Center. "The meticulous sample return and curation process was essential to preserving these pristine samples and unlocking these secrets."
Complementing the organic discoveries, scientists identified 11 minerals within the Bennu samples, providing a snapshot of the asteroid's watery past. These minerals, formed through the evaporation of saltwater, point to an ancient environment conducive to the chemistry of life. Similar aqueous environments have been observed or inferred on other celestial bodies, including Ceres and Enceladus, suggesting that Bennu is not unique.
Tim McCoy, curator of meteorites at the Smithsonian's National Museum of Natural History, emphasized the significance of these findings. "These papers work in tandem to explain how life's ingredients came together on this aqueously altered asteroid."
Despite these groundbreaking discoveries, some mysteries remain. Amino acids exist in two forms, "left-handed" and "right-handed," and while life on Earth predominantly uses the left-handed variety, Bennu contains an equal mix. The reason for life's "left-handedness" remains an open question.
"OSIRIS-REx has been an extraordinary mission," said Jason Dworkin, OSIRIS-REx project scientist at NASA Goddard. "The data paints a compelling picture of a solar system teeming with the potential for life. The ultimate question, of why life has only been definitively observed on Earth, continues to intrigue and inspire us." The mission's findings provide a powerful impetus for future exploration and the search for life beyond Earth.