Michael Hesse began his career with the theory of large-scale magnetohydrodynamic phenomena, such as the magnetic reconnection in the Earth’s magnetosphere. He soon became a world-leading specialist in numerical plasma simulations, and as a post-doc he expanded his expertise toward microscopic simulations utilizing particle-in-cell techniques. His outstanding publication record illustrates his success in applying these techniques to a wide area of key problems in space physics, often urgently needed in interpretation of spacecraft observations.