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Alternate Environmental Control and Life Support System (ECLSS) technologies were evaluated to reduce Space Station resources and dependence on expendables resupplied from Earth to sustain a multiperson crew in low-Earth orbit. Options were evaluated to close the oxygen (O2) loop by removing carbon dioxide (CO2) from the cabin air, reducing the CO2 to water, and electrolyzing the water to provide metabolic O2 for crew consumption. Options were also evaluated to close the urine/flush, condensate, and hygiene water loops to provide potable water for crew use. Specific evaluation parameters were derived which included weight, power, volume, maintenance, resupply consumables, and technology readiness.

A baseline ECLS system for a lunar base manned intermittently by four crewpersons and later permanently occupied by eight crewpersons has been designed. A summary of physical characteristics for the intermittently manned ECLS system includes a launch weight of 10,590 lb, launch volume of 955 ft3, 90-day resupply weight of 5972 lb, 90-day resupply volume of 346 ft3, and a power requirement of 10.494 kW. Evolution into a continuously manned base generates the following incremental requirements: launch weight of 19,935 lb, launch volume of 1178 ft3, 90-day resupply of 4928 lb, 90-day resupply of 403 ft3, and power requirement of 10.695 kW. A supplementary study assessed tankage requirements, penalties incurred by adding subsystem redundancy and by pressurizing large surface structures, and difficulties imposed by intermittent occupancy. Alternate concepts using lunar derived oxygen, the gravity field as a design aid, and a city utility type ECLS system offer potential advantages.

Space Station nodes packaging analyses are presented relative to moving environmental control and life support system (ECLSS) equipment from the habitability (HAB) module to node 4 in order to provide more living space and privacy for the crew, remove inherently noisy equipment from the crew quarter, retain crew waste collection and processing equipment in one location, and keep objectionable odor away from the living quarters. In addition, options for moving external electronic equipment from the Space Station truss to pressurized node 3 were evaluated in order to reduce the crew extravehicular activity (EVA) time required to install and maintain the equipment. Node size considered in this analysis is 3.66 m (12 ft) in diameter and 5.38 m (17.67 ft) long. The analysis shows that significant external electronic equipment could be relocated from the Space Station truss structure to node 3 and non-life critical ECLSS HAB module equipment could be moved to node 4.

The NASA Langley Research Center (LaRC), in conjunction with the NASA Goddard Space Flight Center (GSFC), evaluated the impact of an animal science experiment on the Space Station environmental control and life support system (ECLSS). The LaRC-developed ECLSS computer-aided analysis capabilities were used for the evaluation. Equivalent crew size parameters were developed for an animal colony consisting of 96 rodents and 8 squirrel monkeys selected by NASA GSFC as a representative complement for life science research on board the NASA Space Station. Thirteen ECLSS options, along with the analysis assumptions, were established for reclaiming metabolic oxygen (O2) and waste water. In addition, both dedicated and shared options included facilities that were common to both the animal and the crew. The ECLSS options were compared against the Space Station ECLSS baseline provided at the interface requirement review (IRR) at the NASA Johnson Space Center (JSC) in 1986.

The effects of varying carbon dioxide (CO2) and oxygen (O2) concentrations, relative humidity, temperature, and pressure on the production and depletion of trace contaminants in the NASA Space Station Reference Configuration have been evaluated. This evaluation was conducted using a Space Station trace contaminant computer model developed specifically to predict the effects of chemical reactions and physical processes on gaseous trace contaminant concentrations as functions of time. The sensitivity of trace contaminant concentrations to changing CO2 and O2 concentrations, relative humidity, temperature, and pressure was determined. In addition, the effects of changing the initial concentrations of significant contaminants such as nonmethane hydrocarbons and nitrogen oxides on concentrations of other trace contaminants of importance were examined.

A supercritical water oxidation (SCWO) concept was evaluated to determine its potential to reduce the number of processes required to provide an Environmental Control and Life Support System in an Evolutionary Space Station, to reduce the Station resupply requirements, and to enhance the integration of separate ECLSS functions into a single Supercritical Water Oxidation process. Three conceptual design cases were evaluated. The results indicated that the SCWO technology was not a viable substitute for the IOC Space Station ECLSS, because the technology was not sufficiently mature to meet the 1987 Space Station design commitment date. For an Evolutionary Space Station, the SCWO process could enhance the integration of eight ECLSS functions into a single function, thereby reducing programmatic costs. The SCWO technology combined with current onboard food production technology was not a viable option to replace stored food, because food production technology was inefficient.

Seventeen Environmental Control and Life Support System technology options to provide metabolic oxygen and water to sustain a multiperson crew on Space Station missions have been evaluated. The options included state-of-the-art technologies as well as advanced technologies that offer the potential for improvements in Environmental Control and Life Support Systems performance. The methodology for candidate technology recommendations was based upon specific assessment criteria as functions of prelaunch development activities and postlaunch operational considerations. The electrochemical depolarized cell option for carbon dioxide concentration, the sabatier option for carbon dioxide reduction, the static feed water electrolysis option for metabolic oxygen recovery, and vapor compression distillation and multifiltration options for waste water recovery were recommended.

A description is given of a computer program developed at the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) for the assessment of manned space station environmental control and life support systems (ECLSS) technology. The program methodology along with the data base and mission model variables are given for 17 candidate technologies that show potential for supplying metabolic oxygen and water on manned space missions. The data base includes metabolic design loads associated with crew activity, engineering design parameters for each technology option, and cost data required for candidate life cycle cost comparisons. The method for ranking the candidate options in order to provide recommendations for space station application or subsequent development is presented.

Life support systems to support multiman crews on extended space missions will require the development of regenerative systems more advanced than those presently available. This equipment must be maintainable, highly reliable, and possess automatic features to enhance mission success. Presently at the NASA Langley Research Center, a program is underway to provide the technology for such systems. The status of the program is presented which includes a discussion of the Integrated Life Support System (ILSS) now in-house, plans for the development of advanced subsystems, and a summary of the Advanced Integrated Life Support Systems (AILSS) program to provide maintainable subsystems integrated into a multicompartment chamber.