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Conceptual designs for initial, intermediate, and advanced lunar base life support systems (LSS) are under development at JSC. The initial air revitalization, water recovery, and waste management subsystems are based on space station technologies. The intermediate system expands on the initial capabilities; for example, the initial waste management subsystem allows only for compacting and storing solid waste, while the intermediate waste management subsystem includes measures for recovering useful substances from the waste. The advanced system includes biological waste treatment and higher plants to be used for air revitalization and water processing. This paper describes the three systems and discusses the basis for selecting individual processes. System-level mass balances are used to illustrate the interaction of the air, water, and waste loops. The effect of introducing different waste treatment processes into the initial LSS is examined.

The Major Constituent Analyzer (MCA) was activated on-orbit on 2/13/01 and provided essentially continuous readings of partial pressures for oxygen, nitrogen, carbon dioxide, methane, hydrogen and water in the ISS atmosphere. The MCA plays a crucial role in the operation of the Laboratory ECLSS and EVA operations from the airlock. This paper discusses the performance of the MCA as compared to specified accuracy requirements. The MCA has an on-board self-calibration capability and the frequency of this calibration could be relaxed with the level of instrument stability observed on-orbit. This paper also discusses anomalies the MCA experienced during the first year of on-orbit operation. Extensive Built In Test (BIT) and fault isolation capabilities proved to be invaluable in isolating the causes of anomalies. The process of fault isolation is discussed along with development of workaround solutions and implementation of permanent on-orbit corrections.

Orbiter radiator performance provides the most variance in determining the amount of Shuttle Transportation System (STS) Orbiter water available for transfer to the International Space Station (ISS). As radiator performance decreases, dependence upon the Flash Evaporator System (FES), which requires Fuel Cell (FC) water to reject the Orbiter's waste heat, increases. Generally, radiator performance decreases as the ISS assembly size increases (especially as solar arrays are added), and also as beta angle increases. A parametric study has been accomplished that provides a quick-reference table for determining the amount of Orbiter water available for transfer during ISS missions 2A.2 through 7A.1. An hourly Orbiter net water generation rate is reported according to variations in ISS assembly configuration, beta angle, ISS attitude, Orbiter radiator configuration, and Orbiter heat load. Those permutations of higher probability of occurrence than others have been identified.

Crewmember ingress of the International Space Station (ISS) before that time accorded by the original ISS assembly sequence, and thus before the ISS capability to adequately control the levels of temperature, humidity, and carbon dioxide, poses significant impacts to ISS Environmental Control and Life Support (ECLS). Among the most significant considerations necessitated by early ingress are those associated with the capability of the Shuttle Transportation System (STS) Orbiter to control the aforementioned levels, the capability of the ISS to deliver the conditioned air among the ISS elements, and the definition and distribution of crewmember metabolic heat, carbon dioxide, and water vapor. Even under the assumption that all Orbiter and ISS elements would be operating as designed, condensation control and crewmember comfort were paramount issues preceding each of the ISS Missions 2A and 2A.1.