The Same Recipe That Created Life on Earth May Exist on Mars

A PNAS study led by Steven Benner proposes that RNA could form in basalt-hosted, intermittently wet aquifers containing borate, activated phosphate, and stabilized organic sugars, and analysis of samples from asteroid Bennu returned by OSIRIS-REx detected ribose and glucose that relate to prebiotic chemistry.

Scientists are examining how the chemistry that produced RNA on early Earth could also have operated on ancient Mars. A recent study led by molecular biologist Steven Benner describes a geologic setting—basalt-constrained, intermittently hydrated aquifers with borate, activated phosphate, and stabilized organic carbohydrates—where RNA components could assemble. Minerals containing borate (often called borax) can help stabilize the sugar ribose that forms RNA's backbone, and samples returned by OSIRIS-REx from the asteroid Bennu contained ribose and glucose. Researchers note there are still unresolved issues, including how RNA building blocks would have acquired a single handedness. Key findings: - A PNAS paper led by Steven Benner outlines a single geologic environment in which RNA synthesis could occur on Hadean Earth and Noachian Mars: basalt-hosted, intermittently hydrated aquifers with borate, activated phosphate, and stabilized organic carbohydrates. - Borate minerals can stabilize ribose and support its attachment to phosphate groups, addressing a vulnerability of ribose to degradation. - Analysis of samples from asteroid Bennu, returned by OSIRIS-REx and studied by a team including researchers at Tohoku University, reported detection of ribose and glucose. - Basalt glass and rock textures formed by cooling lava or impact melts are proposed to have helped components of RNA link into longer strands. - A remaining scientific challenge is explaining how the building blocks of RNA acquired a consistent left- or right-handed form (chirality). Summary: If the proposed model is supported, a similar set of geochemical conditions could have enabled the formation of RNA on both early Earth and ancient Mars, and some key sugars appear in extraterrestrial samples. Further research is needed to clarify the mechanisms and to resolve the chirality problem; Undetermined at this time.