Chapter III 

 Observational Exobiology 



M. Belton, A. Betz, J. Black, M. Cohen, T. Encrenaz, 



N. Evans, P. D. Felclman, E. Herbst, J. Kerridge, 



C. McKay, J. Nuth, T. Roellig, T. Scattergood, J. Tarter, 



A. Tielens, and J. Veverka 



Since life (as we know it) depends upon its environment for development 

 and survival, the origin and evolution of life are integral parts of the physical and 

 chemical processes that govern the formation and evolution of the planets. The 

 formation and evolution of a planet is intimately bound to the evolution of its 

 sun, a star. Stars themselves are the manufacturing plants for all of the biogenic 

 elements; their birth and death cycle is governed by the laws of physics in this 

 universe. Thus it should be no surprise that in attempting to understand the 

 origin and evolution of the biogenic elements and compounds, the exobiology 

 community has, over the past decade, developed an increasing interest in the 

 results of astronomical observations. Much of what is known or conjectured 

 about the processes that led to the abiotic chemical evolution of organic matter 

 in the vicinity of the planet Earth was derived from the observations conducted 

 by astronomers and astrophysicists. The observational results have been com- 

 bined with knowledge gained from the collection and analyses of pristine mate- 

 rials of terrestrial and extraterrestrial origin, and have been supported by labora- 

 tory attempts at chemical synthesis and theoretical models of complex 

 chemistries in various environments. There now appears to be a marginally self- 

 consistent outline of the pathways leading from the stellar nucleosynthesis of 

 carbon, oxygen, nitrogen, phosphorus, sulfur, and other biologically significant 

 trace elements to their inclusion into planetesimal sized bodies within the young 

 protosolar nebula. While this outline is self-consistent, it is far from complete, 

 and many of the most interesting details remain to be supplied by more obser- 

 vational, experimental, and theoretical effort. 



Hubble Space Telescope 



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