Section headings and selected papers: Exobiology in Space. Exobiology: results of spaceflight missions, H D Mennigmann. Chemical and Early Biochemical Evolution. Synthesis of organic compounds in interstellar dust and their transport to earth via comets, J M Greenberg. Modification of simple organic solids in space: energetic carbon interactions with solid methane, A Patnaik et al . A quantitative assay of biologically important compounds in simulated primitive earth experiments, Y Honda et al . Nucleic acid analogues and the origins of replication, A W Schwartz. Life Without Oxygen. Microbiology and biochemistry of the methanogenic archaeobacteria, D R Abbanat et al . Present-day biogeochemical activities of anaerobic bacteria and their relevance to future exobiological investigations, R S Oremland. Early Environment of Mars: Potential for Chemical Evolution. Development of Alba Patera volcano on Mars, J Raitala. Biological nitrogen fixation under primordial Martian partial pressures of dinitrogen, J M Klingler et al . Planetary Protection Issues and Sample Return Missions. Planetary protection policy overview and application to future missions, J D Rummel. Peroxides and survivability of microorganisms on the surface of Mars, R L Mancinelli. Modulation of Biological Evolution by Astrophysical Phenomena. Periodic mass extinctions: difficulty with astronomical explanations, M E Bailey et al . Author Index.
