Hydrogen peroxide on Mars and icy moons: Implications for the search for extraterrestrial signatures of prebiotic chemistry

ABSTRACT Hydrogen peroxide (H 2 O 2 ) is increasingly recognized as an important molecule in prebiotic chemistry that potentially had a large impact on life’s early evolution. We highlight recent examples of H 2 O 2 in prebiotic syntheses that model potential protometabolic reactions. Recent discoveries have revealed multiple abiotic production mechanisms for H 2 O 2 , suggesting its prevalence in prebiotic and extraterrestrial environments, an idea that is supported by the detection of H 2 O 2 in the Martian atmosphere and on the surfaces of icy moons. Given that Earth’s active geological processes have erased records of the earliest prebiotic chemical processes, we hypothesize that extraterrestrial environments that produce H 2 O 2 such as Mars and icy moons may still have similar types of chemistry occurring, and the discovery of such reactions by advanced space missions would offer invaluable insights into prebiotic chemistry. To test our hypothesis, experimental and theoretical studies aimed at modelling prebiotic chemistry in these H 2 O 2 -producing environments are required. We propose the general principle of “Where There is Water, There is H 2 O 2 ” as an astrobiology guideline that supplements and refines the traditional “Follow the Water” approach used to plan space missions.