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The story of life on Earth did not begin at the planet’s birth 4.6 billion years ago. During the Hadean eon, a hostile, molten world endured for roughly six million years before the first habitable conditions emerged in the following Archean eon. While life itself appeared only in that later period, the Hadean’s “heavy bombardment” phase—when the nascent planet was bombarded with asteroids and comets—may have been instrumental in seeding Earth with the ingredients that would later give rise to life.
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In January 2025, two papers described the analysis of samples returned by NASA’s OSIRIS‑REx spacecraft. Launched in 2016, the probe visited the near‑Earth asteroid Bennu and brought back four ounces of dust and pebbles in September 2023. The first study, published in Nature Astronomy, identified sodium‑rich minerals, amino acids, formaldehyde, and ammonia—components essential to life. Fourteen of the twenty protein‑forming amino acids required on Earth were present, along with five nucleobases that compose DNA and RNA. The high concentration of ammonia could have reacted with formaldehyde to synthesize additional amino acids, a key step toward the formation of proteins.
Daniel Glavin, co‑author of the paper, emphasized that the organic molecules were “real extraterrestrial organic material formed in space and not a result of contamination from Earth” (CBS News).
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While Glavin’s team examined the chemical composition, a separate analysis led by Smithsonian curator Tim McCoy and London naturalist Sara Russell—published in Nature—focused on the mineral record. They uncovered eleven evaporite minerals, including calcite, halite, sylvite, and the rare trona, indicating that the parent body of Bennu once hosted bodies of salty water that later evaporated. The presence of these minerals suggests that the asteroid may have once supported lakes or even oceans, creating a liquid environment capable of facilitating the complex chemistry that the OSIRIS‑REx samples revealed.
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These discoveries underscore that the raw ingredients for life existed beyond Earth’s surface and that the early solar system was capable of producing them. Yet, no definitive evidence of life has been found on any other planet or moon, and the exact pathway from these molecules to living cells remains unknown. The heavy bombardment, while destructive, may have delivered essential compounds that allowed life to ignite on Earth. As research continues, scientists plan to analyze additional samples from Bennu’s parent asteroid and from other bodies, including the forthcoming OSIRIS‑APEX mission to the near‑Earth asteroid Apophis in 2029.
With each new piece of data, the possibility that life’s origins may extend across the solar system—and perhaps beyond—grows ever more plausible.
