How universal are life’s building blocks? Organic molecules have been detected on rocky bodies, meteorites, and in the interstellar medium. Do prebiotic molecules from exogenous or planetary sources predetermine the possible monomers that lead to biopolymers? Do prebiotic polymerisation processes select certain monomers over others and if so, how is it influenced by planetary conditions? We aim to investigate the role of the environment on the polymerisation of exogenous-delivered, monomeric building blocks of life. We will examine prebiotic polymerisation routes at the interface of atmosphere and mineral surfaces with and without water in conditions relevant for Early-Earth, Mars and Titan. We will investigate the branching effects of polymerisation using key differences between monomers from exogenous and in-situ sources, including the effect of the carbon chain and enantiomer excess. We will examine the control of the environment on these polymerisation processes, focussing on the structural properties of minerals and the oxidation effect of the atmosphere. Probing the polymerisation routes will allow us to guide analysis for (future) planetary missions as well as provide critical links between other PEPSci projects with rocky body environments. ( Credits)