of interest in itself, but will help in planning for future comet sample return 

 missions. An incremental increase in the depth of understanding of cometary 

 processes could be achieved by the study of artificial comets in space. Two types 

 of experiments are envisioned, one in which gas is released and monitored to 

 simulate the coma and tail, and one in which a dust-and-gas-laden ice ball is 

 released and monitored to simulate the nucleus and its immediate vicinity. Such 

 experiments in space are the logical next step in the study of comets, bodies that 

 contain much information of interest to exobiologists concerning the early 

 history of the solar system and the environment of the early Earth. 



6.3.3 The Survival of Microorganisms in Space 



While most scientists are convinced that life evolved on Earth from nonliving 

 matter, the idea that life evolved elsewhere, traveled across space, and inoculated 

 our own world is an intriguing one. One of the requirements of this panspermia 

 hypothesis is that microorganisms can survive in the space environment. As this 

 environment cannot be simulated on the ground, the viability of microorganisms 

 in space must be tested in space. Therefore, a variety of microorganisms should 

 be exposed to the space environment and their viability determined under differ- 

 ing, controlled conditions. Such studies are relevant to exobiology in the strict 

 sense of the word, and can provide an experimental test of the panspermia 

 hypothesis; they are important to biology in providing new information on the 

 adaptability of life to extreme environments. 



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