The chemical elements from carbon onwards have all been produced in stars. The elemental abundances we observe in our solar system, meteorites and distant stars provide us with clues of how these elements were produced in a variety of astrophysical sites and processes. However, many open questions remain, and a key to finding the answers is to study the nuclear reactions occuring in stars and stellar explosions which are responsible for element formation. These reactions often involve unstable nuclei which do not naturally occur on earth - this provides a challenge to make these nuclei accessible experimentally. This ERC project addresses major open questions in the field, related to the origin of elements heavier than iron, the origin of cosmic gamma ray emitters, and the source of neutrons in low mass stars. We aim to directly measure key nuclear reactions involving unstable particles, using upgraded and new world-leading international accelerator facilites, combined with advanced, sensitive detection systems, which are purpose-built within the ERC project.