These proceedings contain 56 papers that cover such topics as extraterrestrial organic chemistry and the origins of life; life on Mars; planetary protection for Mars missions and chemical evolution on Titan.

The papers presented at these Topical Meetings addressed research issues concerned with the growth of plants and the recycling of wastes within artificial ecosystems such as Controlled Ecological Life Support Systems (CELSS), the development of bioreactors for use in space and carbon cycling in natural ecosystems. It is anticipated that a better understanding of the dynamics and mechanisms of the natural ecosystems of the Earth, in which human activities play an increasingly important role, will provide significant information to support the development of artificial ecosystems for life support. In turn, it is expected that in developing ecosystems for the specific purpose of supporting humans in space, a better understanding of natural ecosystems will emerge.

Two Spacelab flights with biological payloads on board took place in 1991 and 1992. The highlights of the investigations together with the results of relevant ground-based research are reported in this volume.

The fifty-seven papers presented in this volume give a complete overview of the knowledge to date in radiation biology. The accessibility of the unique radiation environment in space and the increasing involvement of human beings in space missions have initiated substantial research activities in the various fields of space radiation biology dealing with radiation detection and measurement; biological mechanisms of the hard component of cosmic radiation; impact of space environment on radiobiological processes and also radiation protection issues. Besides offering opportunities for radiobiological experiments in space, the current space exploration programme even requires the collection of radiobiological data in space and at accelerators as baseline information for estimating radiation risks to humans on future space missions and for establishing radiation standards for manned spaceflight.