Understanding the Potential Role of Oxychlorines in Destroying or Altering Chemical Biosignatures on Mars

• Applicant: Professor Dr. Dirk Schulze-Makuch
• Subject Area: Microbial Ecology and Applied Microbiology ; Analytical Chemistry ; Organic Molecular Chemistry - Synthesis and Characterisation
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 450240159

Perchlorate (ClO4-) has been discovered on Mars in multiple locations including at high latitudes by the NASA Phoenix mission and subsequently by the SAM instrument onboard the Curiosity Rover, and also in Mars meteorites. Its presence at about 1% levels has had major negative implications in terms of its ability to destroy organic compounds, and thus chemical biosignatures of any microbial life, by production of highly oxidizing radicals and other oxychlorines during its photochemical formation. Our goal is to combine experimental and field studies to investigate the role of oxychlorines in destroying or altering chemical biosignatures on Mars. To address this goal, the three main objectives of this project are to: 1. Conduct laboratory experiments under Mars simulated conditions to investigate the effects on biosignature molecules of highly reactive intermediary products generated during the UV-driven production of oxychlorine (ClOx) species.2. Undertake a field expedition to the hyperarid core of the Atacama Desert (Chile) to collect samples and make in-situ measurements to investigate the relationship between biosignature preservation, alteration, or destruction, and ClOx levels at and below the surface. 3. Verify whether the breakdown products from the laboratory experiments can also be found in the samples from the Atacama Desert and compare the breakdown products and the organic compounds in the field samples with the organic compounds detected on Mars by the Curiosity rover.Although a variety of studies of degradation pathways and products for amino acids and organic compounds under UV irradiation have been reported over the past 20 years, none have investigated the effects on biosignature-class molecules in the presence of oxychlorine salts and the oxidation products of such exposure. The results will be of significance because we will for the first time be determining the extent of alteration or destruction of chemical biosignatures that should be present on Mars if it ever harbored life.The proposed work is directly relevant to understand the potential of life to adapt to different environments, and the identification of biosignatures for in situ and remote sensing applications. This includes research on the forms in which prebiotic organic matter formed on planetary surfaces has been preserved and the range of planetary environments that might be amenable to life. The proposed sites in the Atacama Desert are highly relevant Mars analogue sites and will provide an increased understanding of the role of perchlorate in altering chemical biosignatures, and thus in understanding the potential detection of chemical biosignatures and the habitability on Mars.

• DFG Programme: Research Grants
• International Connection: Chile
• Cooperation Partner: Professor Dr. Pedro Zamorano