About 270 different molecular species have been identified in space, and this number continues to grow steadily. The surprising molecular diversity bears witness to an active reaction network, in which molecular ions are the main drivers of chemistry in the gas phase. While the advanced capabilities of modern telescopes may help us to unravel the molecular composition of the universe, to gain a comprehensive understanding of the observational results requires detailed knowledge of the molecular formation, excitation, and destruction mechanisms. However, laboratory studies of many fundamental reactions that dominate the chemistry of interstellar space are still a major challenge. In this framework, the Cryogenic Storage Ring (CSR), operated at the Max Planck Institute for Nuclear Physics in Heidelberg, serves as a unique testbench to study cold molecular ions in the gas phase. With a circumference of 35m, temperatures below 10K, and residual gas densities on the order of 103 cm-3, the CSR is currently the largest and most ambitious electrostatic storage ring project in the world. Its experimental stations allow for merged beams collision studies involving molecular ions, neutral atoms, free electrons, and photons under true interstellar conditions. I will present the instrumental capabilities of the CSR, together with recent results with relevance to astrophysics and perspectives for future experiments. Those unable to attend the colloquium in person are invited to participate online through Zoom (Meeting ID: 942 0262 2849, passcode 792771) using the link: https://zoom.us/j/94202622849?pwd=dGlPQXBiUytzY1M2UE5oUDRhbzNOZz09