Asteroid Bennu Yields Building Blocks of Life, Challenging Origins Theories
Recent analysis of samples collected from asteroid Bennu by the OSIRIS-REx mission has revealed a surprising abundance of organic molecules, including amino acids adn nucleobases – the fundamental components of proteins and genetic material. This discovery, detailed in a publication in the Proceedings of the National Academy of Sciences, suggests that the chemical precursors to life were more readily available in the early solar system then previously understood.
The research team confirmed the presence of 14 different amino acids within the Bennu samples, several of which are essential nutrients for humans and cannot be produced by the human body. Critically,all five common nucleobases – adenine,guanine,cytosine,thymine,and uracil – which form the building blocks of DNA and RNA,were also identified.
Importantly,the presence of non-biological variants of these molecules effectively rules out the possibility of terrestrial contamination.These molecules do not originate from living organisms on Earth, strongly indicating an extraterrestrial source.
The diverse mineral composition of Bennu, described as resembling a “dense and varied fruitcake,” points to a complex history of chemical reactions. Researchers found that no single process can account for the variety of organic compounds present,suggesting multiple reactions,many involving liquid water,contributed to their formation. This indicates that prebiotic chemistry in space is far more intricate than previously believed.
This finding supports the hypothesis that comets and asteroids delivered a diverse “starter kit” of chemical compounds to early Earth, providing the necessary building blocks for the emergence of life. However, the discovery also presents a challenge for the search for extraterrestrial life. The ability of tryptophan, and potentially other complex amino acids, to form through non-biological processes means their detection elsewhere in the universe cannot be automatically interpreted as evidence of life.
The analysis underscores the importance of sample return missions like OSIRIS-REx, which allow for the preservation and detailed study of fragile molecules crucial to understanding the origins of life. Further analysis is planned to definitively confirm the origin of tryptophan within Bennu, but the initial findings demonstrate that the universe likely contained a far richer supply of the ingredients necessary for life than previously imagined.
(Image Credit: NASA – bennu and other nearby asteroids.)
