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3 Environmental Monitoring and Control Introduction The closed environment of a spacecraft with a closed-loop or nearly closed-loop life support system will present unique challenges to both scientists and engineers who must manage the quality of the crew's air and water. It will be necessary to maintain the composition, temperature, feed rates, and operating pressures of the solid, gaseous, and liquid constituents to ensure the mechanical ''health" of the system (i.e., reliability, maintainability) and the health of the human crew. Environmental monitoring and control (EMC) encompasses the internal environment of a human occupied spacecraft, including the atmosphere, water supplies, and all surfaces. The term "monitoring" implies continuous vigilant oversight of the status of these areas over time to ensure that conditions are maintained within acceptable limits. (This also implies that acceptable limits have been established and that detection methodologies are available.) The term "control" implies some form of feedback to the systems responsible for maintaining each parameter. In most cases to date, the feedback has been in the form of a message to the crew, via the Caution and Warning System, that a parameter is moving out of the acceptable range. The message may include an indication of the possible causes. In a few cases, such as monitoring of in-line water quality, feedback can be directed to the processor logic, which would result in operational adjustments.
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Technical and Scientific Topics Related to Environmental Monitoring and Control Environment inside a Crewed Spacecraft The initial atmosphere of a NASA spacecraft is a mixture of nitrogen and oxygen. Anything else in the atmosphere, including water, heat, chemicals (i.e., gases, vapors, and particulates), and microorganisms can be considered a contaminant if they are present at unacceptable levels. Sources of contamination include living organisms (people, plants, animals, and microbes), equipment, experiments, the chemical or physical degradation processes of spacecraft materials, and the external environment (in a planetary setting). Environmental monitoring for such contaminants inside a spacecraft must go beyond traditional methods. Tables 3-1 and 3-2 summarize the categories of potential contaminants in spacecraft environments. The nearly airtight nature of space vehicles, the limited availability of evacuation options, the possibility that crews will spend 600 to 1000 days1 in a closed environment (for a mission to Mars), and other aspects of space flight have resulted in and will continue to necessitate stringent, sometimes unique, requirements regarding atmospheric contaminants. The focus on EMC at NASA has been on chemical contaminants. A wide variety of these chemicals have been identified, and their individual concentrations have been measured in the cabin air during previous Space Shuttle or Mir missions. One can expect that similar contamination will be present during future space missions, especially if the missions become more complex (such as revisiting the Moon, transit to Mars, or the development of lunar or Mars bases). Some Table 3-1 Major Categories of Contaminants Category Examples Water Vapor, liquid from condensation and leaks Gases CO2, CO, NOX, SOX Inorganic chemicals Cations, anions Volatile organic compounds Formaldehyde, benzene, etc. Nonbiological particles Combustion particles, fibers from fabrics, paper, etc. Living microorganisms Viruses, bacteria, fungi Plant parts Pollen, leaf hairs, etc. Nonliving particles from biological sources Allergens, toxins, danders, urinary, salivary, fecal proteins, endotoxins, etc. 1 Sample scenarios for short-duration and long-duration human missions to Mars are provided in America at the Threshold: America's Space Exploration Initiative (Stafford et al., 1991).
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Table 3-2 Potential Sources for Some Major Contaminants Source Examples of sources Contaminant examples Humans Respiratory effluents, skin, excretory products, exhaled air CO2, volatile organic compounds, and other metabolic wastes, viruses, bacteria, dander Water Showers, hand washing, clothes washing, dish washing, drinking Bacteria, viruses, organic and inorganic chemicals Surfaces Microbial growth in condensation, dust accumulation Bacteria, bacterial toxins, fungal effluents (spores, allergens, toxins, volatiles), other allergens, other volatile chemicals Food Cooking, spoilage organisms Volatile chemicals, fungal effluents (spores, allergens, toxins, volatiles), bacteria and their products Cabin materials and processes Natural offgassing, fire, cleaning materials, etc. Volatile chemicals, nonbiological particles, CO, CO2 Scientific research Chemicals, animals Trace volatiles, organic compounds, animal allergens, other metabolites and associated microorganisms Plants Leaf surfaces, growth medium, etc. Volatile chemicals, pollen, plant hairs, bacteria, fungal spores and other effluents Wastes Transformation products of biological, chemical, and physical interactions CO2, NOX, H2S, NH3, O2, methane, microorganisms types of contaminants are well characterized; others have been recognized but not yet measured. Because conditions are likely to vary over time throughout a long-duration mission, the capabilities of monitoring and control systems for chemical contaminants need to be able to adapt to new conditions. For example, contaminants that may not have been identified at the beginning of a mission or that may form as a result of reactions with other contaminants or environmental media may require attention after the mission has begun. Qualitative methodologies provide information on the types of chemical contaminants present in an environment. This information can be used for making decisions related to the development of spacecraft maximum allowable concentrations (SMACs) and can also provide direction for the development of technology for contaminant removal as well as limits for equipment that outgases into the spacecraft environment. SMAC levels drive the requirements for detection methodologies and sensitivities, as well as for contaminant removal and the efficiency and performance requirements of transformation technologies. At the
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present time, NASA has established SMACs for approximately 40 trace contaminants, based on chemical speciation and the duration of exposure.2 SMACs provide guidelines for chemical exposure during normal and emergency operations. However, these established safe levels for airborne contaminants are only applicable for relatively short durations (1 and 24 hours; 7, 30, and 180 days). These limits may not be appropriate for longer missions, and need to be reevaluated and extended. As longer-term SMACs are developed, the concomitant development of accurate and reliable quantitative measurements will be critical for ensuring that standards are met. Microorganisms as pollutants have received far less attention than chemical pollutants because of the complexity of populations, the widely disparate agent-specific requirements for sensitivity, and the general lack of methods of analysis that can be used in the spacecraft environment. To date, spot-check sampling has been done for a limited range of microorganisms, and guidelines for interpreting the data have been based on extremely limited information. SMACs have not been developed for any microbial contaminants. Rationale for Monitoring A basic purpose of monitoring is to diagnose and feed back information to a warning or control procedure, so that the risk of unacceptable exposures is minimized. The value of monitoring is reduced if control will be too slow to prevent or significantly diminish negative health effects, or if no control is possible. For example, 90-day intervals between monitoring events for agents of infectious disease, as planned for the ISS, may be too long to be of significant use for crew protection. The incubation period for most infectious diseases is significantly less than 90 days, and many diseases are likely to run their course before they are indicated by the currently planned monitoring system. In some cases, no interval sampling technique is likely to be effective. For example, contagious and waterborne virulent diseases can develop following single, low-level exposure events. Therefore, if any exposure occurs, environmental monitoring is likely to be too late, and measures to prevent additional cases must focus on the isolation and treatment of infected individuals or sources of contaminants. Useful environmental monitoring to control such diseases would have to focus on very low detection limits (single agents in large volumes of air/water) in real time. Even when control of exposure is not possible, however, monitoring may produce valuable data for the design of future missions, or may indicate the presence of agents that could pose a future risk of disease. Monitoring for infectious agents involves identifying specific reservoirs and developing monitoring protocols based on background data and risk assessments that include the nature of the 2 The most recent report on SMAC levels is by the NRC's Committee on Toxicology, Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants (vol. 2) (NRC, 1996).
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TABLE 3-3 Microbiological Monitoring and Control Prioritization Procedural Steps Description Prioritization of monitoring needs This decision needs to be based on: (1) failure, health risk, and mission impact; and (2) the ability to adequately monitor so that unacceptable risk can be prevented. Follow-up sampling Monitoring and control must account for upset conditions as well as preventive measures. Once a problem has occurred, sampling may be important for tracing the source and for focusing controls. This is an acute response process, and is very different from routine process monitoring. In the case of a human health problem, sampling can be focused on specific causal agents. Guidelines are: (1) Is the agent present in one or more reservoirs? and (2) Is there a logical pathway for exposure? In case of equipment failure or off-nominal conditions, sampling can be focused on the specific failure scenarios that could have caused the fault. Guidelines/standards Neither monitoring nor sampling are useful unless guidelines are available for interpreting data, and the guidelines are tied to control strategies. Ideally, guidelines should be based on the risks of failure or disease or the risk of a mission being compromised. However, guidelines that specify monitoring below the detection limit of available technologies may not be useful unless they acknowledge this problem and are clear enough to guide the research and development of new technologies. Monitoring/control There need to be clear links between monitoring and control. As the EMC program matures, monitoring protocols should be closely tied to control procedures. As with detection limits, control procedures should be within the limits of available technology unless this issue is clearly acknowledged and addressed with a view towards specifying requirements for the development of new technologies. agent, the probability of presence and exposure, as well as likely levels of infectious agents and variability over time. These kinds of detailed assessments regarding when and how monitoring should be used would enhance the viability and cost-effectiveness of operational EMC programs planned for future missions. The baseline plan for the ISS is still based on culture methods to detect bacteria. Standard microbiological techniques encourage fungi and bacteria to grow in the space environment. Given the close quarters and closed environment of the ISS, this technique should be reevaluated (especially for fungi, which produce spores that readily become airborne). Table 3-3 shows a general outline for the prioritization and use of monitoring and control schemes.
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For long-term missions beyond LEO, when rapid returns to Earth will be impossible, real-time monitoring of potentially toxic contaminants will become increasingly essential. First, the crew must be aware of chemical hazards when they occur; then, they must be able to determine the source, nature, and risk associated with exposure; last, they must take appropriate measures. Airborne chemicals may be hazardous even at very low concentrations. The capability of detecting, identifying, and quantifying airborne contaminants in a timely manner must have high priority. Therefore, the continual development of sensitive, reliable, and validated technologies for monitoring spacecraft atmospheres for chemical contamination is essential. Crew Health and Safety Chemical Pollutants The monitoring of airborne chemical contaminants must be detailed enough to ensure the health, performance, and comfort of the crew. Continuous (or almost continuous) monitoring of major air components would be desirable. The frequency of sampling for trace contaminants must take into account the ordinary fluctuations of the atmosphere. The specificity and sensitivity of the analytical methods need to meet the established SMAC levels. The design of such analytical systems depends directly on requirements imposed by the established SMACs. Monitoring chemicals in the air presents some temporal and spatial challenges. Typically, sampling is performed on a periodic basis from discrete locations. This protocol is adequate for analyzing long-term trends but does not address localized, transient conditions and peak exposure levels. For example, the inadvertent release of contaminants may be a significant threat to the health and safety of the crew. One possible way to detect an unexpected release would be to develop ''concentration-activated" sensors designed for specific hazardous chemicals that would be triggered when a specified concentration is reached. Spacecraft lack natural convection and air circulation due to the absence of gravity. Inadequate ventilation resulting from obstructed vents or faulty equipment could potentially result in air stagnation or pocketing of contaminants. This is particularly critical in crew areas. Sample ports for monitoring are typically hardwired to one or several locations within a module, which means that these conditions may go undetected. One possible solution could be to develop a roving sampler that could traverse the pressurized volume and could also be used to sample behind racks and panels for pockets of stagnant air. Another possible solution could be portable monitoring devices worn by crewmembers. Another issue related to monitoring in space is that some sensors rely on gravity-dependent properties for operation (e.g., hydrogen detectors). In these instances, gravity-independent alternatives will need to be developed for use in space applications.
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Microbial Pollutants Diseases related to microbial and other biological pollutants, including infections from environmental and other sources, hypersensitivity diseases, and biological toxicoses, may be of special concern for long-term space missions. Contagious and waterborne virulent diseases will be of concern on board space stations and on permanent lunar or Mars colonies where isolated groups could be periodically exposed to new agents. Another possible concern is the activation of latent viruses or the mutation of strains with limited virulence that may be resident in water systems or members of the crew. Microbial amplification will occur on crewed spacecraft and planetary outposts. Biofilms, macroscopic layers of microorganisms and their secretions that adhere to moist or immersed surfaces, are inevitable in recirculating water systems on surfaces, filters and in charcoal beds. Fungi and bacteria will also grow wherever water is inadvertently present in reservoirs, on materials, or on surfaces. Microbial amplification levels will depend primarily on the duration of continuous occupancy and the level of environmental control (including failures). Such microbial amplification raises concerns about specific infectious diseases in the closed spacecraft environment, where space-induced changes in hosts, and possible changes in the virulence of organisms, may increase risks to the crew. In addition to infections, however, microbial amplification in closed environments can increase the risks of hypersensitivity and toxic diseases. Exposures to mixtures containing bacteria and fungal spores can lead to adult-onset asthma and hypersensitivity pneumonitis, diseases for which human risk factors are unknown (i.e., one cannot screen crews for susceptibility). In addition, evidence is accumulating that exposure to microbial toxins in closed environments may result in an array of symptoms, ranging from eye irritation to severe central nervous system reactions that could seriously compromise the health of the crew and their performance capabilities. Systems Engineering and System "Health," Reliability, and Maintainability The technologies supported by the EMC program will ensure life support system "health" as well as human health. This means that the components of environmental systems will have to be monitored, assessed across a variety of performance characteristics, and controlled. The complexity of closed-loop systems will mean that "system health" technologies must have many of the same characteristics as required for maintaining human health: very high reliability; rapid response times a high degree of autonomy; and ease of maintenance. Meeting these requirements will most likely require the development of new, possibly revolutionary, sensors. Major new developments will almost certainly be required to meet the reliability and goals of control autonomy. In all cases, the use of system studies, in close conjunction with studies of advanced life support
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technologies (including testbed programs) will be necessary. Sensor placement studies, changes in expected performance due to low gravity or microgravity operation, and complex system dynamics are some areas where system modeling and assessments will play a critical role. Microorganisms may also play a role in system health. If allowed to develop unchecked, bacterial biofilms will foul water systems and may lead to system deterioration as well as unpotable water. Fungi will degrade any organic material if sufficient moisture and oxygen are available. Damp conditions and condensation will lead to fungal deterioration of colonized materials, possibly even vital components of life support systems. Fungi are well-known to colonize and destroy most carbon-containing materials, including cellulosic materials (paper, fabrics), lignin (paper, wood products), natural rubber, some plastics, and other materials. Current Status of the Environmental Monitoring and Control Program The EMC program is relatively new. Previously, sensor development for space environmental systems had been the responsibility of either life support or biomedical research programs. In 1994–1995, OLMSA found it appropriate to create a separate EMC program. OLMSA recognized that the complexity of the environmental system will increase greatly as system closure becomes more complete and as mission durations increase. Advances in sensor technologies may enable new approaches to monitoring and controlling spacecraft environments. The 1996 Advanced EMC Strategic Plan provides strategic goals, objectives, deliverables and metrics for the program. The plan seems to meet the needs of the program and is a well conceived document that defines a clear, reasonably achievable mission. The goals and objectives of the EMC program, as stated in the Strategic Plan, are shown in Table 3-4. The deliverables of the EMC program are shown in Table 3-5. NASA has also drafted a requirements document for the development of advanced EMC technologies, the objective of which is to define a set of requirements for EMC systems for advanced human missions, based on prioritization and risk assessment. The committee reviewed this document in draft form.3 The document, which was developed as a part of the Environmental Monitoring and Controls Workshop (held in April 1996 in Pasadena, California, sponsored by JPL), focused primarily on two essential needs: (1) the requirements for the health of the crew; and (2) the requirements for monitoring life support systems. It was 3 The final version of this document, Advanced Environmental Monitoring and Control Program: Technology Development Requirements (NASA, 1996b), was published by NASA in October 1996, after the committee had completed its data-gathering process, on August 31, 1996.
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TABLE 3-4 Goals and Objectives of the EMC Program Goals Objectives Associated with Each Goal Determine the requirements for EMC systems aboard future human spacecraft * Establish and continuously update integrated environmental monitoring requirements * Determine the state of the art in environmental technologies in other government agencies, industry and academia in order to maximize efficacy of limited program funds Obtain state-of-the-art, revolutionary technologies for spacecraft EMC * Sponsor development of high-risk, high potential return environmental sensor and control systems technology development * Obtain state-of-the-art technologies to enhance EMC from industry, academia, and other government agencies or off the shelf as appropriate for NASA's use Provide mature, tested environmental monitoring technologies for use in flight systems * Select EMC technologies whose proof of concept has been demonstrated for further development in increasingly realistic environments * Provide EMC systems for use in integrated testbeds * Provide advanced integrated EMC technologies for use in flight systems for the human exploration and development of space Provide the benefits of NASA-developed EMC technologies to U.S. industry and for improving human welfare * Establish criteria in announcement of research opportunities and subsequent progress reviews encouraging early technology transfer * Establish partnerships and Memoranda of Understanding with industry, academia and government organizations to use NASA-developed EMC technologies for the economic benefit of the U.S. and for improving human welfare Source: NASA, 1996a. recognized that, in order to maintain the health, comfort and well-being of the crew, these two needs are closely related and will be essential to the success of future missions. Research Currently Funded by the Environmental Monitoring and Control Program The 17 technical development projects funded in 1995–1996 by the EMC program are summarized in Table 3-6. The majority of current NASA-funded EMC research is focused on the detection of chemical compounds and infectious agents in air and water. The focus of chemical analysis has been primarily on organic compounds. Other
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TABLE 3-5 EMC Schedule and Program Deliverables Time Period Top Level Deliverables of the EMC Program 1995–2000 * Breadboard demonstrated sensor systems capable of monitoring a wide variety of atmospheric contaminants * Initial demonstration of microbial sensor systems * Breadboard demonstrated water contamination sensor systems * Initial demonstration of advanced integrated control systems for ALS systems * Flight demonstration of selected air monitoring technologies 2000–2005 * Integrated monitoring and control systems demonstrated in ground testbeds * Initial integration of microbial sensors achieved * Initial testing of sensor and control systems on board ISS (rack level) * Continuing development of advanced EMC technologies 2005–2010 * Fully integrated monitoring and control systems demonstrated in high-fidelity ground testbeds with humans in the loop * Full autonomous control of ALS systems achieved * Integrated monitoring and control systems demonstrated aboard ISS * Continuing development of advanced EMC technologies 2010–2015 * Integrated EMC of ISS achieved * Delivery of technologies suitable for EMC on lunar and planetary missions Source: NASA, 1996a. TABLE 3-6 Funded Technical Development Projects (1995–1996) Application Area Number of Projects Comments Air/trace contaminant control 8 All multiple gas sensing technologies: 2 entirely new technologies 2 miniaturizations of existing projects 3 high reliability, smaller, low power technologies 1 adaptation of other technology Water 2 1 miniaturization of an existing project 1 increased sensitivity and miniaturization of an existing project Microbiological control 4 1 biofilm study 3 microorganism identification/quantification Process control 3 1 modeling/sensor placement study 1 trend prediction study 1 gas sensing study
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contaminants that may become important, particularly for long-duration missions, include water and airborne contaminants that can accumulate from processing equipment and endotoxins produced by microorganisms. Relatively little work is being done in the area of airborne particulate contaminants, such as inorganic materials, fibers, metals, bacteria and fungi that do not cause infectious disease but may still contain allergens or toxins (e.g., from pollen), material debris, or liquid droplets. The Advanced EMC Strategic Plan stresses an efficient program operating on a lean budget. This seems appropriate, given budget realities and the fact that a specific, long-term or planetary mission has not yet been selected by NASA. By these standards, the schedule of deliverables in the Strategic Plan is probably overly-ambitious, partly because the program budget was only approximately $4 million in FY96. The FY95 budget was $1.84 million, $1.01 million of which was spent on R&D grants and contracts, $600,000 on technology development at JPL, and $230,000 on the development of SMACs. High Priority Areas for Environmental Monitoring and Control Technology Research and Development Summary Finding. The development of risk-based prioritization processes, understanding the ramifications of system perturbations, and the development of a detailed plan to use the ISS as a testbed for advanced EMC technologies and issues related to environmental chemical contaminants and microbiology on long-duration missions are the highest priority technologies. Finding. Evaluating and prioritizing health and system risks with respect to environmental exposures is an important element of the EMC program. Research focused primarily on ground-based areas of concern may have limited relevance for the (long-duration) space environment. Recommendation 3-1. NASA should develop a process whereby research and development programs for environmental monitoring and control are based on relative risk and use risk prioritization to determine requirements. Risk analysis should include the impact of exposure on health, the likelihood of exposure, impact of exposure on the mission, and the ability to control exposures. An immediate program focus should be the analysis of risks presented by failure and upset modes. Work should be prioritized to address these risks based on overall program needs. Finding. Understanding what happens when a system is perturbed will be critical to controlling ALS systems. Not enough effort has been expended on developing requirements related to potential perturbations or upset conditions. For instance,
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the need to understand biological process upsets and their ramifications is a significant change from current investigations using steady-state conditions for process optimization. Many traditional P/C and microbial techniques for facilitating ALS require sensitive monitoring and rapid, effective control mechanisms during both ideal (steady-state) and transient (off-nominal) conditions. Therefore, system optimization incorporating such monitoring and control strategies sufficient to address those factors that could lead to system instability and failure is crucial, as is the capability to institute swift and effective corrective action. This approach would permit an analysis of the reliability and outcomes necessary for sustained human survival by incorporating integrated P/C and biological processes necessary for resource recycling and potential loop closure. This approach is also consistent with the desire for system reliability in the EMC Strategic Plan. Recommendation 3-2. Experiments with testbeds should be intentionally perturbed to simulate worst-case conditions (e.g., upset scenarios) and should be monitored for results. These test results should then be used to establish critical requirements for sensors and control systems, recognizing that effective control is not possible without adequate understanding of cause and effect. Finding. The ISS provides a unique opportunity for NASA to improve the fundamental understanding of how living and working in a microgravity environment can influence the needs of various ALS systems and how such an environment may accumulate and distribute toxic environmental contaminants. Human and animal studies for assessing the physiological changes during long-term space flights require that sensors be developed and strategically placed to assess the adequacy of strategies for controlling possible life support system perturbations and/or failures. Recommendation 3-3. NASA should develop a plan for testing and demonstrating environmental monitoring and control sensors, controls, and other technologies using the International Space Station as a testbed to help determine human health risks for future long-term missions beyond low Earth orbit. Finding. Evaluating and prioritizing the risk of long-duration chemical and microbial exposures is an important element of the EMC program. Research focused on ground-based concerns may not be relevant for the (long-duration) space environment. Recommendation 3-4. Microbiological concerns should be included with other (related) monitoring and control efforts, including the possible development of multi-use sensors, to focus on important (or controllable) problems in the spacecraft environment. High-priority technical issues in microbiology include:
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(1) developing methods and processes for screening crews to prevent infectious and hypersensitivity diseases; (2) understanding surface contamination by fungi and bacteria in water and ventilation systems; and (3) developing risk-based guidelines for infectious agents and appropriate monitoring and control strategies. Relationship between the Environmental Monitoring and Control Program and the Success of Future NASA Missions Summary Finding. Long-duration, crewed missions cannot succeed without a healthy EMC program that has the means to follow the NASA Strategic Plan. Finding. Adequate monitoring and control of advanced human life support cannot occur without the development of a successful advanced EMC system. If a system is developed that does not meet all of the risk-based needs for monitoring and supporting humans results in a human death or in catastrophic mission failure, the endorsement and realization of any future crewed missions would be severely limited. It should be self-evident that a complex, integrated life support system (even with components that perform adequately) will be of little functional value if it cannot be controlled to perform within specifications. The design and use of advanced sensors and controls will enable the development of a functioning, lower cost, integrated system that can respond rapidly to environmental changes and perform to requirements continuously over a period of years with minimal maintenance. The development of a sensory and control system that will achieve these objectives must start with a specific set of long-range goals, as presented in the Strategic Plan. Recommendation 3-5. The committee recommends the appropriate allocation of resources, budget, and personnel needed to fully accomplish the programmatic goals as stated in the Advanced Environmental Monitoring and Control Program Strategic Plan. Program Objectives and Milestones Summary Finding. The Advanced EMC Program Strategic Plan is a good one. However, meeting the current schedule will require more realistic resource planning, and accelerated research on control systems. Finding. The Advanced EMC Program Strategic Plan is well focused and comprehensive. The goals and objectives are responsive to the mission of providing ''future spacecraft with advanced microminiaturized networks of integrated sensors to monitor environmental health and accurately determine and control the
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physical, chemical and biological environment of the crew living areas and the environmental control system." The Advanced EMC Program Strategic Plan provides a relevant and useful template for the development of an advanced EMC program. The document outlines the mission, goals, objectives, and deliverables for a program, and ably demonstrates a clear, concise vision of the contributions the program must make. The plan is not overly prescriptive, and provides guidance for the future, regardless of which programmatic structure or future mission is selected. Addressing NASA's unique needs are important to deriving new technologies from limited intramural and extramural resources. The attempt to link monitoring and control technology development deliverables within a projected implementation schedule is a good feature of the Strategic Plan, as is the recognition of a need to measure progress toward meeting goals, objectives and associated deliverables. The metrics of cost and performance, in terms of reliability and risk reduction, will need definition as EMC technologies for use in space mature. Recommendation 3-6. NASA should develop a test plan for integrated system control that includes validation. The test plan should be driven by an analysis of nominal operations as well as expected failure modes, and any other anticipated vulnerabilities of the system. The skills and facilities needed to fully implement the proposed schedule should be identified and appropriate funds should be allocated. The necessary resources should be balanced against the expected budget, and an implementing schedule should be developed accordingly. Finding. The Advanced EMC Program Strategic Plan is a well conceived document, and its emphasis on risk prioritization and the development of metrics to measure the success of technology and systems under development is crucial. However, the EMC program has not yet explicitly defined NASA's unique needs, such as the need for miniaturization and the challenges of operating in microgravity. Regardless of the mission selected, new and novel monitoring and control technologies must correspond with the ALS goals of smaller, cheaper, closed systems that can run autonomously for years. One shortcoming of the Strategic Plan is that it does not define how NASA's truly unique needs will be planned for and accommodated in the EMC program. Examples of these needs are the challenges associated with measuring and interpreting data in microgravity, and the identification of technical challenges associated with allocating volume and electric power. The Advanced EMC Program Strategic Plan provides a long-term strategy for designing programs and projects that need to be accomplished if the long-term goals and objectives of the Advanced Human Support Technology Program are to be met. This Strategic Plan addresses the needs for new technologies in EMC necessary for the future human exploration of space. The plan can be an
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effective aid to NASA for prioritizing limited resources by ensuring that relevant technologies are identified as critical. The plan highlights the goals and objectives associated with: (1) technical requirements needed for monitoring and controlling the environment of future spacecraft; (2) criteria for assessing, prioritizing, and selecting technologies for further development; and (3) identifying areas where EMC technologies can be transferred to benefit and improve human welfare and enhance the quality of life on Earth. The plan properly focuses on research necessary to improve NASA's ability to sustain a long-term human presence in space. Recommendation 3-7. NASA should implement the environmental monitoring and control program largely as described in the 1996 Advanced Environmental Monitoring and Control Program Strategic Plan. The program should be continuously monitored to ensure that these goals are fully met and are on schedule. NASA should consider revising the document with an overlay of NASA's truly unique needs in the area of environmental monitoring and control. Overall Scientific and Technical Quality Summary Finding. The scientific and technical quality of the EMC program needs to continue to be enhanced by ongoing peer reviews and the interaction of NASA personnel with outside scientists and engineers. NASA should ensure that oversight of the program is provided by highly qualified scientists and engineers. Finding. Existing tendencies toward insularity, not only within NASA as a whole, but within specific NASA centers and even within specific programs, is limiting access to state-of-the-art science and developments as well as to the benefits derived from continuous peer review. Recommendation 3-8. Resources should be provided for NASA scientists and engineers involved in environmental monitoring and control projects to have more interaction with the broader scientific and engineering communities. This could take the form of expanding and maintaining active participation in professional societies, sponsoring internships for NASA scientists in appropriate academic settings, and publishing in peer-reviewed publications. Interaction with other organizations with shared interests should be pursued to determine if progress made elsewhere can contribute to the environmental monitoring and control program. Organizations to consider include the Occupational Safety and Health Administration, the National Institute for Occupational Safety and Health, the Department of Defense, the Department of Energy, and the Environmental Protection Agency. Finding. The oversight of monitoring programs requires broad knowledge and advanced training as well as a full awareness of the special requirements imposed
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by the spacecraft environment. This type of oversight has been minimal for microbial monitoring and control (as described in the draft requirements document) and would significantly benefit the current EMC program. Recommendation 3-9. NASA should take steps to minimize the isolation of sub-disciplines and media (e.g., air, water, surfaces) within the environmental monitoring and control specialty. This could promote the development of multi-use sensors and the implementation of integrated physical/chemical and biological life support systems. The oversight of NASA microbiological activities should be assigned to a scientist who has broad experience in environmental microbiology (air and water) as well as the qualifications and authority to interact with NASA administrators, engineers, physicians, and others to help establish priorities and to obtain adequate resources. Program Requirements Summary Finding. NASA should make an effort to define NASA's truly unique EMC requirements. One means that must be used to do this is through the development of risk assessment methodologies to prioritize contaminants. If risk assessments indicate that monitoring is necessary, long-term limits for contaminants must be developed. Finding. NASA needs to provide methodologies for determining contaminant limits, and for prioritizing environmental contaminants that require limits. Setting these limits is a critical first step in the development of monitoring and control requirements for ALS systems. Although the Advanced EMC Program Strategic Plan states that SMACs for longer durations in space need to be established, it is not evident that a plan is being developed to establish them. NASA recognizes that the spacecraft environment may become periodically contaminated by trace chemicals, which could adversely affect the health and well-being of the crew or impair their performance. A wide variety of chemical contaminants have been identified and their concentrations measured during Space Shuttle and Mir flights. One can expect that planetary missions or a crewed lunar base will require humans to spend extended periods of time in space with the possibility that they will be subjected to long-term exposures in contaminated environments. At present, NASA has set SMAC limits for certain airborne toxicants but only for durations ranging from 1 hour to 180 days. For extended missions, it will be critical to have operational guidelines and procedures in place for assessing possible human health risks from long-term exposure to such contaminants. Similar standards will be needed for waterborne contaminants. Limits will have to be set low enough to prevent either acute or long-term health risks. As these longer-term limits are developed, the concomitant development of accurate, quantitative measurements and the operating
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ranges of monitoring and control instruments can be defined, which will be critical to ensuring that these standards are met. Recommendation 3-10. Spacecraft maximum allowable concentrations have been established for many, but not all, airborne chemical contaminants for durations of up to 180 days. NASA should now develop or adapt methodologies for assessing the relative environmental health risks from airborne and waterborne contaminants on long-term space missions. Theoretical risk assessment models could be developed for expected contaminant exposures and for some pollutants. Biomarkers could be useful for monitoring responses to long-term exposure. Finding. There is a continuing need for the integration of ground-based research and spaceflight research. In planning and designing future long-duration missions, success will depend on many factors, such as the requirements of the mission, technology readiness, timeliness, and cost constraints. These technological challenges may be successfully met through an extensive array of both ground-based and space-based research. Such interaction requires a well coordinated, integrated program with the capability to stimulate and accelerate innovative ground-based research and testing. Such programs are necessary in order to have confidence in the safety of long-duration spaceflight missions. Extensive research with well controlled environments on Earth can be performed before applying the technology to space. Ground-based research and testing can significantly reduce the high costs, health risks, and logistical penalties of space-based experimentation. The ISS will provide a more realistic environment than ground-based research for further tests of EMC technologies and solutions for long-duration space missions. Recommendation 3-11. Existing and developmental ground-based technologies and models should be assessed for their application to the space environment. Program Direction and Organization Summary Finding. A successful EMC program will depend on an appropriate organizational structure, proven technology development capabilities, and the development of a mechanism that integrates the capabilities of NASA centers. Finding. The budget for the EMC program is likely to be constrained. The program managers plan to make the best use of limited resources by focusing on new technologies to meet NASA's needs. Because of the goals and budget of the program, the day-to-day administration of the program should be separate from programs with other responsibilities (i.e., flight operations, life support technology testing, etc.) so that EMC program managers are not compromised by other responsibilities.
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Communication between NASA centers working in EMC appears to be poor. This is probably partly related to fears of downsizing, the isolation of projects, and poorly defined roles. This lack of communication has had a negative influence on the program. The current work in EMC at JSC is focused on supporting the operational aspects of the Space Shuttle and ISS programs. Planning for long-term needs does not appear to be part of the current EMC program at JSC. The current work in EMC at JPL is clearly relevant to the development of advanced sensor technology. JPL has experience in miniaturization and the development of complex control systems. It has less experience with crewed missions than the other centers working in human support. For a technology development program such as the EMC program, management of the program should reside in an organization with a background in leading relevant technology development projects, such as the miniaturization of sensors, microgravity applications and controls. The group should strongly emphasize allocating enough staff to perform the research, and maintain strong ties with academia. Less critical, but also important, should be the ability to work interactively with the developers of advanced life support system hardware, system simulations, and testbeds. This will become increasingly important to program management in later years, particularly as control needs become better defined by maturing system-level tests and simulations. A proven capability for technology development in areas needed by this program is thus critical, as are experience managing relatively small intercenter programs and well-established relationships with academia. JPL is an example of a center that has demonstrated these qualities (i.e., experience developing novel technologies, strong academic ties with the California Institute of Technology, and management of the New Millennium Program), despite their somewhat limited experience with human missions. Recommendation 3-12. NASA should develop a programmatic structure with clear, simple lines of responsibility and funding. A panel of experts to advise and critique the program should be an integral element of this structure. This panel should include professionals from outside NASA as well as from each NASA center involved in the program. Finding. Insufficient interaction among the various NASA centers working in EMC has limited the efficiency and cost-effective use of available talent and resources. The self-sufficient, insular style of operation observed by the committee will have to change in order for NASA to maintain a core capability in the centers. The centers involved in EMC have not been working together to improve communications and the exchange of information. Recommendation 3-13. A mechanism should be developed for integrating the research activities in environmental monitoring and control at various NASA
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centers without eliminating valuable capabilities. NASA should eliminate duplications of effort and increase efficiency and productivity, thereby promoting the likelihood of program success. Synergism with Other Programs Summary Finding. Cohesive interactions with the ALS program, and regular, planned exchanges of information throughout OLMSA, including the EVA and SHF communities, are critical to the success of the EMC program. The program is also likely to benefit from interactions with other government agencies. Finding. Scientifically sound and technically achievable EMC deliverables are intrinsic to the development of closed-loop, autonomous ALS systems. For example, with future long-term missions, real-time monitoring and control of both system fidelity and the accumulation of potentially toxic contaminants will be essential. The Advanced EMC Program Strategic Plan recognizes that the human health requirements for environmental monitoring will be developed by the aerospace medicine and medical sciences communities, and that these requirements will determine the threshold limits, sensitivities, and accuracies of monitoring instrumentation. It is also true, however, that maintaining contaminants below these threshold limits will depend on the ability of the system to control the atmospheric and water conditioning components. Thus, adequate interaction between the developers and those who generate requirements for ALS will be critical to the success of the advanced EMC tasks. Responding to the needs identified by the medical community will not suffice. Adequate attention must be paid to the development of equipment to ensure that medically determined limits are met. Recommendation 3-14. The development of highly automated monitoring and control technologies that are fully capable of interacting directly with systems that control environmental contaminants and life support systems should be a high priority. The environmental monitoring and control program and the advanced life support program need to directly address the necessary synergy between monitoring/control issues and advanced life support technologies. Therefore, the plans for environmental monitoring and control and the advanced life support programs should be developed in a cohesive and complementary fashion. The environmental monitoring and control program should also work closely with programs that are developing requirements or standards in related areas, such as noise or radiation on long-duration missions, so that cross-over, or dual-use, technologies can be more readily identified. At a minimum, those elements of the environmental monitoring and control program that may have some bearing on radiation protection and noise mitigation should be identified.
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Finding. The continuous interaction and communication between toxicologists and microbiologists, physicians, advanced life support engineers (developing processor requirements), and engineers and scientists responsible for monitoring and control technologies are critical. Interaction with engineers in the other human support programs is also critical. A key to the success of the EMC program is maintaining a continuous interface with scientists focusing on various health and human factors issues that may be associated with spaceflight, as well as with those engineers responsible for designing, developing, and applying new monitoring and control technologies. Such interaction should begin in the initial planning phase of the process so that an understanding of the relevant scientific data and technologies can be used for future technology development and criteria for prioritizing certain scientific goals and missions can be established. This will help planners ensure that necessary research and testing will be identified and that resources will be available to accomplish the tasks. This interaction will help ensure an adequate, systematic knowledge base, which will be useful for designing critical systems that will operate efficiently and reliably in space. EMC needs to aggressively encourage such interactions among other components of the HEDS Enterprise. The effectiveness of this interaction needs to be periodically reviewed by experts from other field centers, industry, and academia. Recommendation 3-15. NASA should develop a program for personnel exchanges or regularly scheduled exchanges of information between the environmental monitoring and control program and the three other programs in the OLMSA Advanced Human Support Technology Program. Finding. NASA needs to coordinate research goals and accomplishments with other government agencies, such as the U.S. Department of Energy, the National Institutes of Health, the National Science Foundation, the Environmental Protection Agency and the U.S. Department of Defense, as well as with relevant academic and industrial participants. Recommendation 3-16. NASA should consider including representatives from outside agencies and other key organizations on the advisory panel recommended above to help support the environmental monitoring and control program. Dual-Use Technologies Summary Finding. There will be many technology transfer opportunities both into and out of the EMC program. NASA should seek to develop these opportunities as the program matures. Finding. In order to fully capitalize on the array of technology transfer opportunities, NASA should seek to expand its partnerships with industry, academia, and
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other government organizations engaged in the development and application of similar and complementary monitoring and control technologies. Many terrestrial-based closed or isolated environmental settings have requirements similar to those for spacecraft or planetary habitats. Dramatic advances in the monitoring and control of technologies operating in restricted environments, e.g., medical facilities, mining operations, submarines, and ''sick buildings," may be relevant to the space program and vice versa. For example, the miniaturization of monitoring technologies could lead to terrestrial applications, such as inexpensive, home-based contaminant monitors. The development of new, sensitive biomarkers of exposure and effects could be used to monitor humans in a variety of potential exposure situations on Earth. Recommendations 3-17. NASA and the environmental monitoring and control program should continue to interact with academia and industry, as well as with other government agencies, for the transfer of useful technologies and to seek opportunities for collaborative efforts in the planning and financing of the environmental monitoring and control program. However, technology that addresses issues directly related to crew safety, and not "spin-offs," should be the primary driver of the program. NASA should also strive to work with other government agencies that fund research in related areas, such as the Occupational Safety and Health Administration, the National Institute for Occupational Safety and Health, the Department of Defense, the Department of Energy, and the Environmental Protection Agency. References NASA (National Aeronautics and Space Administration). 1996a. Advanced Environmental Monitoring and Control Program: Strategic Plan. Washington, D.C.: NASA. NASA. 1996b. Advanced Environmental Monitoring and Control Program: Technology Development Requirements. Washington, D.C.: NASA. National Research Council (NRC). 1996. Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants. Vol. 2. Committee on Toxicology, Board on Environmental Studies and Toxicology. Washington, D.C. : National Academy Press. Stafford, Thomas P., et al., 1991. America at the Threshold: America's Space Exploration Initiative. Washington, D.C.: White House Office of Science and Technology Policy.
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