The capabilities provided by today's geophysical and astrophysical instruments allow us to study our planet and the universe with greater detail and precision. This situation empowers us to join along the exciting new frontiers in earth and space sciences and do our own computations. In this talk, I present a plan to provide a GNU platform encouraging the dissemination of computational methods for geophysical and astronomical studies in a free software environment. I also review the challenges ahead, propose ways to solve them, and show how individuals or groups of individuals can contribute.