  Dust grains play a central role in the physics and chemistry of cosmic
environments. They influence the optical and thermal properties of the medium
due to their interaction with stellar radiation; provide surfaces for the
chemical reactions that are responsible for the synthesis of a significant
fraction of key astronomical molecules; and they are building blocks of
pebbles, comets, asteroids, planetesimals, and planets. In this paper, we
review experimental studies of physical and chemical processes, such as
adsorption, desorption, diffusion, and reactions forming molecules, on the
surface of reliable cosmic dust grain analogues as related to processes in
diffuse, translucent, and dense interstellar clouds, protostellar envelopes,
planet-forming disks, and planetary atmospheres. The information that such
experiments reveal should be flexible enough to be used in many different
environments. In addition, we provide a forward look discussing new ideas,
experimental approaches, and research directions.
