Named in honor of Bertram D. Donn for his fundamental contributions to our understanding of solar system astrophysics. In addition to proposing an innovative theory of cometary composition, formation and evolution, Donn succeeded in deriving generally accepted fundamental properties of cometary nuclei that form the basis of current theories. He also carried out very original research on cometary structures using fractals and on the condensation of pre-cometary and interstellar materials. (M 18461) _ _.