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Space-faring crews must have safe breathing air throughout their missions to ensure adequate performance and good health. Toxicological assessment of air quality depends on the standards that define acceptable air quality, measurements of pollutant levels during the flight, and reports from the crew on their in-flight perceptions of air quality. Air samples returned from ISS on flights 8A, UF2, 9A, and 11A were analyzed for trace pollutants. On average, the air during this period of operations was safe for human respiration. However, about 3 hours into the regeneration of 2 Metox canisters in the U.S. airlock on 20 February 2002 the crew reported an intolerable odor that caused them to stop the regeneration, take refuge in the Russian segment, and scrub air in the U.S. segment for 30 hours. Analytical data from grab samples taken during the incident showed that the pollutants released were characteristic of nominal air pollutants, but were present in much higher concentrations.

Space-faring crews must have safe breathing air throughout their missions to ensure adequate performance and good health. Toxicological assessment of air quality depends on applicable air-quality standards, measurements of pollutant concentrations, and crew reports of air quality. Samples of air were obtained during ingress and egress of the Zarya and Unity modules on missions 2A and 2A.1. The results from 2A suggest that trace pollutants were at safe levels and that there was good air exchange between the modules. Results from the 2A.1 flight also showed that trace pollutants were at acceptable concentrations; however, there was evidence of inadequate mixing between the modules during the hatch-open operations. Furthermore, the 2A.1 crew reported after the flight that the air quality seemed to cause symptoms during their operations in Zarya, particularly when more than one crewmember was working inside open panels for some time.

Computer controls are increasingly being employed in systems ranging from simple to very complex. A new trend is to extend these computer systems to include monitoring schemes to detect malfunctions. An example is provided by new automobiles sold in the US, Canada, and Europe. By law they must include “on-board diagnostics” designed to detect certain malfunctions in the powertrain system that may cause excessive emissions. The present article outlines some of the fundamental concepts of system's monitoring and general principles for the design of such monitors.

Space Station Freedom (SSF) modules may be unattended for months during the Man-Tended Capability (MTC) phase of the program. The accumulation of airborne contamination from materials offgassing or contingency incidents (e.g., thermodegradation) raise concerns about crew health and safety from the first crew entry throughout the MTC phase. Computer modelling of the MTC phase, and experiences from previous space flight missions confirm that caution must be exercised during nominal first entry operations. This paper will describe first entry procedures used in the industrial setting and examples of the consequences when first-entry procedures were not followed. Experiences during the Skylab program will be presented to highlight the necessity for carefully planned operations. Anecdotal experiences from previous Spacelab missions and the results of first entry samples from the International Microgravity Laboratory (IML-1) will be detailed.

Compared with previous U.S. space flight missions, the risk of atmospheric contamination on board Space Station Freedom (SSF) is substantially increased because of the large number of on-board experiments, long-term storage of chemical wastes, and the release of offgas products into the closed environment over the station's 30-year lifetime. Degraded air quality aboard SSF could affect crew health and safety as well as mission success. This paper describes the development of technologies for an on-board Volatile Organic Analyzer (VOA), an essential component of the Environmental Heath System (EHS) air-quality monitoring strategy that warns the crew and ground personnel if volatile compounds exceed safe exposure limits. Achieving the performance requirements established for the VOA within power and weight constraints led to a novel approach in which gas chromatography (GC) was combined with ion-mobility spectrometry (IMS).

The capabilities of the U.S. Space Station Freedom (SSF) will allow a variety of scientific investigations in the biological and materials sciences. The complexity and duration of some planned investigations far surpass those flown to date on Spacelabs and carry an increased risk of accidental release of toxic compounds. This risk is further increased by the presence of large amounts of utility chemicals for SSF systems. Past experiences on Shuttle flights have confirmed the potential for airborne contamination emanating from both payload and Shuttle systems as a result of thermodegradation during flight. This paper describes the SSF Environmental Health System's air-quality monitoring strategy and instrumentation. A two-tier system has been developed, consisting of first-alert instruments that warn the crew of airborne contamination and a volatile organic analyzer that can identify volatile organic contaminants in near-real time.

A computer system for data acquisition and analysis has been assembled and tested as an engineering development tool for advanced diagnostic techniques. This system includes custom hardware and software to facilitate high-speed acquisition of data, both digital and analog. The digital data is acquired via a time-stamping procedure, whereas the analog signals are sampled with a multiplexed A/D converter. By simultaneously monitoring both types of signals available to the engine control module, the performance parameters of an engine can be analyzed as functions of either time or engine position. Examples of misfire detection are given which illustrate the need for accurate digital data. Other examples include high-resolution velocity profiles of a defective engine, and samples of signals obtained from a normal engine.