Fragmented Deoxyribonucleic Acid in Rocks  and Its Significance for Studying Life on Mars and Eart
Detecting biomolecules in rocks is vital for understanding life's evolution on Earth and its possible existence on Mars. Curiosity rover measured Total Organic Carbon (TOC) levels of 201–273 ppm in 3,500 million years (Ma)-old Martian mudstones exposed to radiation for 78 ± 30 Ma. We demonstrate that DNA can be extracted and sequenced from terrestrial sedimentary rocks with TOC ranging from 182 to 63,000 ppm, yielding 184,000 to 3.8 million nucleobases from a 0.5 g sample. After exposure to 10.45 MGy of radiation (equivalent to 136 Ma on Mars), nucleobase degradation was assessed, with radiolytic constant of K = 0.17 MGy?¹ in microbialite (2,800 years old) and oxide iron formation (2,930 Ma old) samples. Despite fragmentation, 1.48–8.45% of sequences remained taxonomically identifiable. These findings suggest that DNA fragments can persist in rocks for over 100 Ma, offering a promising approach for life detection in the Mars Sample Return collection.