Risk characterization and the extended spaceflight environment

Recent trends toward prolonged space flights have highlighted concern over potential health hazards for crews occupying a confined habitat for an extended duration mission. Previous spaceflight and remote habitat experiences have identified a large number of compounds that pose potential hazards as space habitat contaminants. A project is underway to prioritize these compounds according to: 1) the degree of potential exposure, 2) known or potential health risks, 3) process- and mission-specific determination of sources of contamination, and 4) preliminary evaluation of mission performance degradations associated with compound contaminant or substitution. An effort is underway to establish a comprehensive database making use of all available national and international data in order to provide a basis from which to evaluate both the impact and the likelihood of long term or transient exposure to these agents. The database will define projected capabilities of Space Station Freedom from early assembly phase through man-tended and permanently-manned capability, previous knowledge of the lunar base environment, and the limited data available from the Viking mission for the Mars environment. This information will then form the basis for mitigation measures including: 1) future process modification or substitution, 2) special provisions for compound containment or use restrictions, 3) re-evaluation of current exposure standards, and 4) reprioritization of information needs (e.g., toxicology, effects on human performance, or re-evaluation of alternative-process mission requirements).