The formation of interstellar molecules on dust grains: surface catalysis in space
Interstellar dust grains are ubiquitous in space and play a subtle but fundamental role in the formation of stars. I will present astronomical observations on the most abundant molecule in the universe: H2. I will discuss how the formation of this simplest molecule on dust impacts the first steps to star formation starting from molecular clouds. I will then present how laboratory astrophysics allows us to tackle these questions. Finally I will show some of the recently unveiled reaction mechanisms between interstellar dust and small and complex molecules.