During solar-type star formation, the chemistry evolves towards the formation of complex organic molecules, eventually setting the stage for the origin of life. This astrochemical evolution depends... Show moreDuring solar-type star formation, the chemistry evolves towards the formation of complex organic molecules, eventually setting the stage for the origin of life. This astrochemical evolution depends on the interaction between gas and microscopic interstellar grains, producing icy grain mantles. This thesis combines ice and gas-phase observations with astrophysically relevant laboratory simulations to constrain some of the key gas-grain processes. From Spitzer observations, the first simple ices, e.g. water and methane, form sequentially through condensation followed by an active surface chemistry, with more source-to-source variation the later in the sequence an ice forms. Close to the protostar the ices are heated. Experiments and their modeling have provided a generalized, quantitative understanding of the induced ice mixture evaporation and segregation, based on relative diffusion barriers alone. When no heat is available UV-induced evaporation still connects the ice and gas; UV photodesorption is found experimentally to be efficient with a similar yield for most ices. UV irradiation also converts simple ices into more complex species and this formation process has been quantified in situ for the first time. Based on these experiments, observations of complex organic molecules around protostars and in comets are readily explained by ice photochemistry. Show less