the collection of rare particles, only cells that were impacted would have to be 

 recovered. Once set into operation, the collector would require very little atten- 

 tion. Perhaps twice a year cells that received major hits would be recovered for 

 Earth return. The scientific reward for operating a large area collector would be 

 the collection of the actual particles that produce the annual showers of come- 

 tary meteors. The larger particles collected would have become radar or faint 

 optical meteors had they been allowed to reach the atmosphere. 



4.6 Conclusions 



The analysis of recovered samples of primitive solar system material provides 

 fundamental insights into the materials and processes that existed in the early 

 history of the solar system and thus into the cosmic evolution of the biogenic 

 elements and compounds. With the improving capabilities to conduct ambitious 

 experiments in Earth orbit, it now seems possible to collect small meteoroid 

 samples (extraterrestrial dust) that can be associated with their parent sources on 

 the basis of common orbital parameters. The major scientific advance that could 

 come from such an endeavor would be the collection of samples that could be 

 confidently identified as originating from the interstellar medium or from 

 specific comets. Even though, for some experiments, particles may be signifi- 

 cantly altered during capture, it is believed that at least their elemental and iso- 

 topic compositions can be accurately measured in the laboratory. The ultimate 

 challenge will involve the development of a device for use on the Space Station 

 that will collect cosmic dust without significant concomitant alteration of its 

 chemical and physical properties. 



Suggestions for Further Reading 



McDonnell, J. A. M.: Cosmic Dust. Wiley and Sons, New York, 1978. 



Sandford, S. A.; and Walker, R. M.: Laboratory Infrared Transmission Spec- 

 tra Measurements of Individual Interplanetary Dust Particles from 2.5 to 

 25 Microns. Ap. J., vol. 291, 1985, p. 838. 



McKeegan, K. D.; Walker, R. M.; and Zinner, E.: Ion Microprobe Isotopic 

 Measurements of Individual Interplanetary Dust Particles. Geochim. Cosmochim. 

 Acta, vol. 49, 1985, p. 1971. 



Brownlee, D. E.: Cosmic Dust: Collection and Research. Ann. Rev. Earth 

 Planet. Sci., vol. 13, 1985, p. 147. 



Tsou, P.; Brownlee, D. E.; and Albee, A. L.: Comet Coma Sample Retu 

 Via Giotto II. J. British Interplanetary Soc, vol. 38, 1985, p. 232. 



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