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MICROBIOLOGICAL CONTAMINATION OF SPACECRAFT.  D.L. Pierson¹, R.J. Bruce², T.O. Groves², N.D. Novikova³, and A.N. Viktorov³.  ¹NASA Johnson Space Center, ²Enterprise Advisory Services, Inc., Houston, TX, USA, and ³Institute of Biomedical Problems, Moscow, Russia.

The International Space Station (ISS) Phase 1 Program resulted in seven U.S. astronauts residing aboard the Russian Space Station Mir between March 1995 and May 1998.  Collaboration between U.S. and Russian scientists consisted of collection and analyses of samples from the crewmembers and the Mir and Shuttle environments before, during, and after missions that lasted from 75 to 209 days in duration.  The effects of long-duration space flight on the microbial characteristics of closed life support systems and the interactions of microbes with the spacecraft environment and crewmembers were investigated.  Air samples were collected using a Russian or U.S.-supplied sampler (SAS, RCS, or Burkard,) while surface samples were collected using contact slides (Hycon) or swabs.  Mir recycled condensate and stored potable water sources were analyzed using the U.S.-supplied Water Experiment Kit.  In-flight analysis consisted of enumeration of levels of bacteria and fungi.  Amounts of microorganisms seen in the air and on surfaces were mostly within acceptability limits; observed temporal fluctuations in levels of microbes probably reflect changes in environmental conditions (e.g., humidity).  All Mir galley hot water samples were within the standards set for Mir and the ISS.  Microbial isolates were returned to Earth for identification of bacterial and fungal isolates.  Crew samples (nose, throat, skin, urine, and feces) were analyzed using methods approved for the medical evaluations of Shuttle flight crews.  No significant changes in crew microbiota were found during space flight or upon return relative to preflight results.  Dissemination of microbes between the crew and environment was demonstrated by DNA fingerprinting.  Some biodegradation of spacecraft materials was observed.  Accumulation of condensate allowed for the recovery of a wide range of bacteria and fungi as well as some protozoa and dust mites.