Stable carbon isotope evolution of formaldehyde on early Mars

The study investigates the stable carbon isotope evolution of formaldehyde (H2CO) in the early Martian atmosphere, focusing on its implications for understanding prebiotic chemistry and the habitability of Mars. The Curiosity rover has detected highly variable and 13C-depleted carbon isotopic values in Martian organic matter, which may originate from simple organic molecules produced by CO2 photochemical reduction. A coupled photochemistry-climate evolution model was developed to analyze carbon isotope fractionation processes in an early Martian atmosphere primarily composed of CO2, CO, and H2. The model indicates that H2CO can become significantly depleted in 13C due to CO2 photolysis, with its isotopic composition influenced by atmospheric conditions such as CO/CO2 ratios and surface pressure. The findings suggest that complex organic matter could form from H2CO, explaining the observed isotopic depletion in Martian sediments. The study also highlights the role of atmospheric pressure in determining the carbon isotopic ratios, with lower pressures leading to higher 13C values in H2CO. Overall, the research provides insights into the carbon cycle on early Mars and the potential for organic matter formation, contributing to the understanding of Mars' habitability.

- The study focuses on the carbon isotope evolution of formaldehyde in early Mars.

- Curiosity rover data shows highly variable and 13C-depleted carbon isotopic values in Martian organic matter.

- A photochemistry-climate evolution model indicates that H2CO can be significantly depleted in 13C due to CO2 photolysis.

- Complex organic matter formation from H2CO may explain the isotopic depletion observed in Martian sediments.

- Atmospheric pressure significantly influences carbon isotopic ratios in H2CO.