Microbial life under Martian permafrost layer

Aromatic compounds have been detected by the Curiosity and Perseverance rovers, suggesting their familiar presence on the Martian surface.1 These organic compounds were previously attributed to water-rock reactions. However, according to our knowledge, no experimental or theoretical evidence substantiates the formation of aromatic compounds purely through water-rock reactions in natural conditions. Here, we propose that the aromatic compounds on Mars are the products of microbial metabolism. These microbiomes inhabit warm regions under the Martian permafrost layer and are fertilized by methane and ammonia formed through water-rock interactions. Most organic compounds on the Martian surface are easier to decompose, leaving behind residual aromatic compounds preserved in Martian soil due to their chemical stability. This model can be further tested using carbon isotope signals of the aromatic compounds.