Exobiology 



liquid water and may contain organic matter like that of carbonaceous meteorites. 

 Titan, the satellite of Saturn, has an atmosphere containing nitrogen, methane, 

 and a variety of simple organic compounds and is thought to represent a model 

 of the chemically reduced atmosphere of the primitive Earth. The opportunity to 

 conduct a detailed study of the organic chemistry of Titan's atmosphere should be 

 pursued on the Titan/Cassini Mission. 



Recent studies have revealed that many asteroids, Comet Halley, other comets, 

 and cosmic dust particles thought to have been derived from comets contain an 

 abundance of the biogenic elements in the form of organic matter. Insufficient data 

 exist, however, to answer such intriguing questions as the degree of molecular 

 complexity in this matter, the mechanisms for its synthesis, and its possible role in 

 the origin and evolution of these primitive objects. Some answers may be pro- 

 vided by the direct study of comets and asteroids, as envisioned for the CRAF 

 and Rosetta Missions, while others may be obtained by conducting experiments 

 under microgravity conditions and by study of cosmic dust grains collected on the 

 Space Station. 



In order to participate in missions, it is necessary to design and construct highly 

 sophisticated analytical instruments and experimental apparatus suitable for 

 measuring the isotopic, chemical, and mineralogical composition of phases 

 containing the biogenic elements on Mars, Titan, asteroids, and comets. These 

 measurements will provide the basis for determining the origin of these phases 

 and for assessing what relationships exist between the processes responsible for 

 synthesis of extraterrestrial organic matter and those that produced the molecular 

 precursors of living systems during prebiotic evolution on Earth. 



Findings for Solar System Exploration 



• Opportunities to fulfill the scientific objectives of Exobiology in space are 

 provided in NASA plans for exploration of the solar system and construction of 

 the Space Station. 



• The exploitation of these opportunities will depend importantly on the 

 development of the analytical flight instruments and apparatus needed to 

 conduct research in space. 



Recommendations 



• NASA should implement its plans for the following missions and facilities 

 over the next several decades: 



— Mars Rover/Sample Return Mission 



— Titan/Cassini Mission 



— Comet Rendezvous Asteroid Flyby Mission 



— Rosetta/Comet Nucleus Sample Return Mission 



— Space Station Cosmic Dust Collection Facility 



— Space Station Gas Grain Simulation Facility. 



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