This is a long-overdue volume dedicated to space trajectory optimisation. Interest in the subject has grown, as space missions of increasing levels of sophistication, complexity, and scientific return - hardly imaginable in the 1960s - have been designed and flown. Although the basic tools of optimisation theory remain an accepted canon, there has been a revolution in the manner in which they are applied and in the development of numerical optimisation. This volume purposely includes a variety of both analytical and numerical approaches to trajectory optimisation. The choice of authors has been guided by the editor's intention to assemble the most expert and active researchers in the various specialities presented. The authors were given considerable freedom to choose their subjects, and although this may yield a somewhat eclectic volume, it also yields chapters written with palpable enthusiasm and relevant to contemporary problems.