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2 ADVANCED LIFE SUPPORT SYSTEMS
Pages 22-60

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From page 22...
... Open-loop life support systems provide all required resources, such as water, oxygen, and food, from storage or resupply, and store waste materials for disposal or return to Earth. In an open-loop system, the resources required increase proportionally as mission duration and crew size increase.
From page 23...
... From Project Mercury through the Space Shuttle, life support systems have been open-loop, using expendables and on-board storage for providing resources and handling waste. Exceptions to the use of expendables for atmosphere revitalization were the molecular sieve for CO2 concentration used on Skylab and the recent incorporation of solid amines to control CO2 on some long-duration Space Shuttle missions.
From page 24...
... Mature technologies will be necessary to provide the confidence that highly reliable ALS systems can meet future mission constraints. TECHNICAL AND SCIENTIFIC TOPICS RELATED TO ADVANCED LIFE SUPPORT According to NASA briefing documents, the mission of the ALS program is to "open the space frontier for exploration, utilization, and development by developing safe, efficient, and effective closed-loop life support systems." The goal is to "provide self-sufficiency in life support for productive research and exploration in space, for benefits on Earth, and to provide a basis for planetary exploration." The objectives of the ALS program are: .
From page 25...
... System analysis and engineering help identify ALS technologies that will significantly reduce life-cycle costs and resolve issues of hypogravity performance and will be key to providing timely transfer of new technologies to NASA missions. Because of their operational history and relative maturity, initial missions back to the Moon or to Mars are likely to rely on existing P/C technologies until other options have been extensively tested and are shown to be flight ready and to meet reliability and safety requirements.
From page 26...
... This is the baseline technology for the ISS, with the possibility of processing CO2 to recover oxygen in the future. The Space Shuttle has used a
From page 27...
... crewed spacecraft to date. These open-loop technologies have the typical mass penalty as mission duration increases.
From page 28...
... filters in the return air ducts. Current technologies use significant amounts of expendable materials, especially activated carbon beds.
From page 29...
... A number of P/C and bioregenerative processes are available to process humidity condensate, urine, and hygiene and wash water for reuse as potable water or for other uses. Distillation is an effective means of purifying water, and several distillation methods for use in space are being developed, including vapor compression distillation (VCD)
From page 30...
... Food scientists, often in concert with military programs, have made significant advances in food preservation and storage techniques in recent years, and NASA has been a participant in, as well as a beneficiary of, this work. Applicability of these techniques for space is being investigated by NASA, and foods preserved by these new techniques are now being flown on the Space Shuttle and are expected to be used on the ISS.
From page 31...
... Incorporating biological components into an ALS system would increase the self-sufficiency of the system by producing food and reducing the need for expendable air, water processing systems, and other materials. A common perception among some engineers, however, is that biological systems are inherently less reliable than P/C systems because the death of a living organism is more likely than an equipment failure, which is repairable and is not usually propagated to other P/C components.
From page 32...
... have been shown to be more common than failures caused by biological problems, such as disease. Because biological productivity is highly dependent on the P/C support components, a fundamental understanding of the effects of short- or long-term mechanical failures on biological productivity is essential before biological components can become critical components of a life support system.
From page 33...
... or for water processing. Closure of the food loop above about 50 percent to reduce the need for food resupply places additional burdens on the temperature and humidity control system to remove excess transpired water and on the waste processing system to recycle CO2 from inedible waste matenal.
From page 34...
... Growing Plants in Space The specific mission environment can play a significant role in the selection of plants to be grown in space. Mission constraints may mean that a small area of plants can be used only for water recycling and diet supplementation.
From page 35...
... However, the structure must still provide protection from radiation and micrometeoroids. Other factors associated with low pressure plant growth environments may offset any mass savings benefit, such as special provisions required for crew access, the development of support equipment designed to operate under low pressure conditions, and the expense of conducting life support system R&D at low pressure on Earth.
From page 36...
... Bioregenerative Components for Recycling Waste The questions of when resource recovery is actually needed and whether the partial recovery of resources might be adequate remain to be answered by systems analysis. In general, however, as mission duration and crew size increase, the recovery and recycling of nutrients from solid wastes to support food production becomes an economical consideration.
From page 37...
... The life support systems being developed in the ALS program must be engineered for many different mission scenarios. The system analysis must be flexible enough to identify high-leverage technology needs so cost-effective designs can be generated when detailed mission requirements become available.
From page 38...
... The development of closed-loop, regenerable systems presents new challenges in mass and elemental partitioning within the system, adding reserves to accommodate system perturbations, understanding the varying time constants for P/C and biological processors, monitoring and controlling the generation and accumulation of microbial contaminants, and integrating biological processes into existing P/C-based life support systems. As the need to address these issues becomes more pressing, especially in the absence of specified mission scenarios, assessing the capabilities of ALS systems will become even more dependent on the development of adequate computer design tools and system models that can simulate processor performance, compare alternative design scenarios, understand system dynamics, develop reliability, availability and maintainability requirements and models, conduct both broad and focused trade-off studies, and perform analyses that support all elements of determining the cost of the program, from the technology development stage to the testbed stage to space-qualified designs.
From page 39...
... But, apparently, they were not sustained or integrated and yielded little follow-up and no integrated effort to guide the overall ALS program. For example, in the 1970s and 1980s, CELSS and P/C trade-off studies were conducted with gross calculations of the relative benefits of growing higher plants in a closed life support system.
From page 40...
... PROGRAMMATIC TOPICS RELATED TO ADVANCED LIFE SUPPORT SYSTEMS NASA Programs and Funding for Advanced Life Support The objectives of the NASA OLMSA ALS program are managed or carried out at NASA headquarters, JSC, ARC, KSC, and MSFC. The program also funds work at universities and in industry.
From page 41...
... . KSC Project Office Training 1 1% 11% Small Business Innovative Research 23% JSC Cente 9% Flight Experiments 3% ARC Project Office 9% JSC Project Office , including Tests and Facilities 21% Supporting Research & Technology 13% FIGURE 2-4 FY96 NASA funding for advanced life support.
From page 42...
... The road map assumes that there will be a significant ability to do research and technology demonstrations and tests on the ISS. However, at the time of this study, no ISS facilities or resources had been designated for ALS research.4 The JSC CTSD plans for future work in ALS are primarily directed toward the "Ground Integrated Testbed" portion of the NASA headquarters road map.
From page 46...
... It is not clear to the committee why the overall NASA policy statement released in February 1996 (NASA, 1996a) calling for the transfer of most program management functions from NASA headquarters to the NASA centers had not been implemented for the ALS program.
From page 47...
... . HIGH PRIORITY AREAS FOR ADVANCED LIFE SUPPORT TECHNOLOGY RESEARCH AND DEVELOPMENT Summary Finding.
From page 48...
... Although the P/C and bioregenerative advanced life support programs have been successfully merged into a single program, the current program does not put enough emphasis on developing P/C subsystem technologies. Except for the teams directly involved with the development of P/C life support systems, there is a sense that the technologies necessary for closed systems have already been developed and are available for future use on long-term missions.
From page 49...
... RELATIONSHIP BETWEEN THE ADVANCED LIFE SUPPORT PROGRAM AND THE SUCCESS OF FUTURE NASA MISSIONS Summary Finding. Advanced life support is a critical technology for the success of long-duration future missions.
From page 50...
... The primary focus of the ALS program from 1996 to 1998 is integrated testing, and programs using integrated human testbeds consume a large portion of the NASA resources allocated to advanced life support systems. According to the FY96 budget, almost half of the approximately $10 million OLMSA will spend is designated for human testbeds.
From page 51...
... Some of the research performed under the ALS program is of world class status, as evidenced by the publication record in prestigious journals. However, the overall scientific and technical quality is uneven.
From page 52...
... Plant growth research should focus on resolving issues unique to growing plants in controlled environments for space applications. Some of these issues include: standardization of procedures for reporting production
From page 53...
... Assuming that management of the program is transferred to the Johnson Space Center, the funding for advanced research and development should continue to be allocated separately from operational programs and responsibilities, such as the Space Shuttle or the International Space Station, to ensure that advanced life support research is not subordinated by immediate operational concerns.
From page 54...
... Recommendation 2-16. Program management should conduct a comprehensive evaluation of the resources required to conduct the advanced life support program, and determine the technical and organizational roles of NASA headquarters and the relevant NASA centers.
From page 55...
... NASA should use the NASA Research Announcements primarily to request proposals at the early levels of technology development. The highest priority technology areas for advanced life support should be carefully and fully communicated in each announcement.
From page 56...
... Areas for cooperation include SBIR, SHE, EMC, the ISS, and the Space Shuttle programs. The ALS program should continue to recognize and make use of the scientific results generated by other OLMSA programs in areas such as plant biology and microgravity sciences related to transport phenomena.
From page 57...
... Recommendation 2-28. The advanced life support program should recognize the International Space Station (ISS)
From page 58...
... The NASA team at Marshall Space Flight Center, which currently has the most expertise in the ISS ECLSS, should continue to be involved in any longterm projects to provide enhancements to the system. Research and development of bioregenerative or plant-based technology should be included in the plans for any advanced life support testbed on the ISS.
From page 59...
... It is expected that some of the waste treatment processes developed in the ALS program will be applicable to this project. A similar project, funded by the National Science Foundation, is under way to apply the waste treatment and plant growth technologies developed in the NASA program to reduce the accumulation of waste at the South Pole Station and to provide a source of fresh vegetables during the winter confinement.
From page 60...
... 1993. Advanced Life Support System Analysis: Methodological Framework and Application Studies.


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