"Modern telescopes like Herschel and ALMA open up a new window into molecular astrophysics to investigate a surprisingly rich chemistry that operates even at low densities and low temperatures. Observations with these instruments have the potential of unraveling key questions of astrobiology, like the accumulation of water and pre-biotic organic molecules on (exo)planets from asteroids and comets. Hand-in-hand with the heightened observational activities comes a strong demand for a thorough understanding of the molecular formation mechanisms. The vast majority of interstellar molecules are formed in ion-neutral reactions that remain efficient even at low temperatures. Unfortunately, the unusual nature of these processes under terrestrial conditions makes their laboratory study extremely difficult.To address these issues, I propose to build a versatile merged beams setup for laboratory studies of ion-neutral collisions at the Cryogenic Storage Ring (CSR), the most ambitious of the next-generation storage devices under development worldwide. With this experimental setup, I will make use of a low-temperature and low-density environment that is ideal to simulate the conditions prevailing in interstellar space. The cryogenic surrounding, in combination with laser-generated ground state atom beams, will allow me to perform precise energy-resolved rate coefficient measurements for reactions between cold molecular ions (like, e.g., H2+, H3+, HCO+, CH2+, CH3+, etc.) and neutral atoms (H, D, C or O) in order to shed light on long-standing problems of astrochemistry and the formation of organic molecules in space.With the large variability of the collision energy (corresponding to 40-40000 K), I will be able to provide data that are crucial for the interpretation of molecular observations in a variety of objects, ranging from cold molecular clouds to warm layers in protoplanetary disks."