The mystery of how life began on Earth may have gained an important clue from space. Scientists have confirmed the detection of all five fundamental nucleobases — adenine, guanine, cytosine, thymine, and uracil — inside meteorites. These are the key building blocks that form the “letters” of DNA (adenine, guanine, cytosine, thymine) and RNA (adenine, guanine, cytosine, uracil).Earlier studies had already identified some of these — such as adenine, guanine, and uracil — in space rocks, but cytosine and thymine had remained difficult to detect. This was largely because they are more fragile and could break down during the harsh chemical extraction methods used in the past, which often involved hot acids.The breakthrough came from an international team, including researchers supported by NASA, who applied a gentler cold water extraction technique. This milder approach preserved the delicate organic molecules that might otherwise have degraded, allowing for their clear identification using advanced analytical tools.
The nucleobases were found in samples from well-known carbonaceous meteorites that fell to Earth over the past century, including the Murchison meteorite (Australia, 1969), the Murray meteorite (USA), and the Tagish Lake meteorite (Canada). A more recent analysis of pristine samples collected directly from asteroid Bennu by NASA’s OSIRIS-REx mission (returned in 2023) also confirmed the presence of all five nucleobases, along with other organic compounds like amino acids and ammonia.While this discovery does not prove that life itself originated in space or was delivered ready-made to Earth, it strongly supports the panspermia hypothesis in a limited form: that essential chemical ingredients for life — the raw materials needed to build genetic molecules — could have formed in extraterrestrial environments (such as on asteroids or in the early solar nebula) and been delivered to our young planet through asteroid and comet impacts during the heavy bombardment period billions of years ago.
These findings build on decades of research and highlight how space chemistry may have played a role in setting the stage for life’s emergence on Earth. The results were published in journals like Nature Communications (2022 study on meteorites) and Nature Astronomy (2025 Bennu findings), emphasizing careful, contamination-free analysis to confirm the extraterrestrial origin of these molecules.
