Advanced Technology for Human Support in Space (1997)

Although no national policies at this time call for human missions beyond low Earth orbit (LEO), a part of the National Aeronautics and Space Administration (NASA) is responsible for long-term technology development that would be applicable to future human long-duration space missions. This part, the Life Sciences Division of the Office of Life and Microgravity Sciences and Applications (OLMSA), requested that the National Research Council (NRC) examine and make recommendations regarding the four programs that make up its Advanced Human Support Technology Program. These programs provide technologies for advanced life support systems, environmental monitoring and control, extravehicular activities, and space human factors engineering, and vary greatly in technology development, scheduling, and funding challenges. Together, these ground-based research and development programs received about $17 million in fiscal year 1996 (FY96), approximately 0.1 percent of the total NASA budget.

In the absence of a policy mandate, the committee based its assumptions on the 1996 NASA Strategic Plan and the 1996 NASA Human Exploration and Development of Space Strategic Plan. These documents identified 2010 to 2020 as the time when new technologies for human missions beyond LEO will be required. In the meantime, from 1997 to 2002, the International Space Station (ISS) is scheduled to be assembled in LEO, about 250 miles above the surface of the Earth, and plans call for operating the ISS for at least 10 years after assembly has been completed.

The findings and recommendations of the NRC Committee on Advanced Technology for Human Support in Space in the four technical areas are briefly described below. General findings and recommendations follow.

In space, life support systems provide the basic functions that sustain life: controlling pressure, temperature, and humidity; providing usable water and breathable air; supplying food; and managing wastes. Technology available today is capable of supporting human crews in space for missions in LEO of short or indefinite duration as long as resupply is readily available, as evidenced by the U.S. Shuttle and Russian Mir programs. All crewed space missions so far have relied on resupply from Earth for some or nearly all of the required consumable resources (oxygen, water, food), as will the International Space Station. Technology to be used on the ISS is capable of recovering water from humidity condensate, waste hygiene water, and crew urine with 80 to 90 percent efficiency. However, no space-qualified technologies are capable of recycling food or oxygen from waste materials, and wastes will have to be discarded or stored for return to Earth. Reducing the transportation cost of resupply, which is a function of crew size and mission duration, is the major incentive for developing advanced technologies that can recover resources from waste materials. Resupplying future missions beyond LEO, missions to Mars for example, will be even more difficult and expensive, if not impossible.

In addition to reducing dependence on resupply, advanced life support (ALS) systems must also be more reliable and self-sufficient enough to ensure crew health and safety. The technical challenge for ALS research and development (R&D) is to provide the designers of future missions with mature technologies and hardware designs, as well as extensive performance data justifying confidence that highly reliable ALS systems that meet mission constraints can be developed.

The current OLMSA program in ALS builds on more than 30 years of development and experience with the operational use of spacecraft life support systems, primarily by NASA and large companies. Research continues at NASA, universities, and in industry to advance recycling technologies for water and oxygen. For approximately 15 years, NASA also has sponsored research on bioregenerative systems that would grow plants in controlled environments to provide food and oxygen, remove carbon dioxide, and transpire clean water.

The physical/chemical (P/C) and bioregenerative life support programs have been successfully merged into a single program, but the current ALS program does not have an appropriate balance of funded projects to bridge the gap between current P/C life support system technology and advanced bioregenerative systems that will be necessary in the nearly closed environments envisioned for permanent planetary bases. Intermediate scenarios will undoubtedly employ hybrid systems that use both P/C and bioregenerative components, and P/C systems will still be required to maintain environmental conditions and to provide redundancy for advanced bioregenerative systems. There is a sense in some parts of NASA and the space community that P/C technologies for recovering oxygen

and water are fully mature technologies and that the only area for advancement is in the development of bioregenerative technologies, but this is not an accurate assessment. There are significant difficulties associated with the use of bioregenerative technologies, and determining the mission scenarios for which they are appropriate should be a major goal of system analyses. Efforts to push the envelope of existing technologies, to think innovatively about P/C technologies, and to address issues associated with hybrid systems should be among the top priorities for technology development.

The management of the OLMSA ALS program—which sponsors R&D at four NASA centers (Ames Research Center [ARC], Johnson Space Center [JSC], Kennedy Space Center [KSC], and Marshall Space Flight Center [MSFC]) and in universities and industry—was in flux throughout the period of this study, although it was informally indicated that JSC will assume responsibility for implementing the ALS program. As of the end of the committee's work, however, neither a program manager nor support structure had been identified by JSC management. This uncertainty has had an adverse effect on the planning and implementation of the program.¹

The technology development road map proposed by NASA headquarters has four major elements: science and technology R&D; low gravity research on the ISS; ground integrated testbeds; and zero-g integrated testbeds on the ISS. The current focus of the ALS program is on ground integrated testbeds. The committee agrees that testbeds play a critical role in the technology maturation process but believes they must be supported by the rigorous and productive development of new technologies and coordinated with systems engineering and analysis. To provide direction for technology development decisions in the absence of a defined target mission, it is essential that systems analysis and trade-off studies be conducted to support testbed-acquired data. The combination of computer-based systems and models and testbed-acquired data makes increasingly detailed system assessments possible through an iterative process involving testbed acquired data, increased understanding of technology, improved fidelity of system models, and trade-offs. Once gaps in data have been identified, they can guide the development of requirements for testbeds, as well as for the structure and format of testbed programs. The committee considers the ground testbeds important and valuable but is concerned about the current balance between testing and technology development.

At the beginning of this study, NASA urged the committee to focus on the development of revolutionary technologies, but there was consensus among the members of the ALS subcommittee that it would be best to investigate both evolutionary and revolutionary improvements concurrently. There is no consistently successful way to solicit, find, or fund proposals for revolutionary technologies

that have a reasonable probability of achieving their objectives. The committee believes that the Small Business Innovative Research (SBIR) Program has provided a significant means for small companies to participate in the development of ALS technology, although closer coordination with OLMSA funded work is needed. The committee found no formal method in place for soliciting and supporting contributions from large industry. Most ongoing efforts and coordination with NASA are largely industry-initiated. Unless industry has a reasonable expectation of funding from NASA for advanced development as a follow-on to their investment, future industry funding will probably be directed to more promising business opportunities, which would erode industry's ability to support NASA's future goals.

The potential for synergy between the ALS program and other NASA and OLMSA programs, especially with the environmental monitoring and control (EMC) program, is significant. The EMC program ultimately validates, and participates in, the proper functioning of ALS systems. As control strategies become more sophisticated, the sensors and monitoring equipment developed for EMC will be integral to an automated life support system. Unfortunately, there appears to be little communication or coordination between the ALS program and the Space Shuttle or ISS programs, although both the Space Shuttle and the ISS are essential to ensuring the utility of ALS projects directed at near-term needs and for providing on-orbit facilities to support technology development. The ALS program should recognize the ISS Environmental Control and Life Support System as a baseline for technology initiatives and should address the evolution of the ISS in concert with the development of tools, processes, subsystems, and systems necessary to support space vehicles and planetary bases.

The EMC program was established in 1994 to develop technology for determining and managing the chemical, physical, and biological elements of a crewed living space in the unique environment of a pressurized spacecraft under conditions of microgravity. EMC must ensure that air and water conditions, including surfaces in contact with air and water, are maintained within acceptable limits. The research currently funded by the program primarily focuses on the detection of chemical compounds. Some work is also being done on detecting microorganisms.

Environmental monitoring entails the continuous oversight of all media (including air, water, and surfaces) via sensors. Environmental control entails feedback of data to the appropriate component(s) of the life support system responsible for maintaining a given parameter within the desired range. Feedback includes various responses, such as caution lights that can be seen by crewmembers or output to a control process that results in operational adjustments. Sources of physical, chemical, and microbiological contaminants include humans and other organisms, food, cabin surface materials, and experiment devices.

EMC technologies and systems, by their very nature, are closely tied to the components of the life support system over which control may be exerted. EMC development is driven by scientific research related to environmental health, which provides a basis for determining the requirements for monitoring and control. As mission duration increases, EMC will become both more difficult and more important to the safety of the crew.

The committee found that the EMC program has a well conceived strategic plan that provides the program with goals, objectives, deliverables, and metrics. The committee recommends that efforts to implement the goal of using risk prioritization to determine requirements should be stepped up. Risks should be evaluated based upon the potential health impact of exposure to hazardous compounds or microorganisms, the likelihood of exposure, the impact on the mission, and the ability to control exposure.

In many cases, other organizations (in both government and industry) will be advancing technologies that are relevant, but not unique, to NASA. Therefore, EMC work should focus on NASA's truly unique needs, such as the effect of microgravity on sensor function and placement and the need for sensors and systems that can function continuously over many years with little maintenance. The NASA EMC program is a small, focused program working on unique products for future crewed space missions. The committee endorses NASA's establishment of an EMC technology program separate from the life support and environmental health programs. Because the EMC program is envisioned as an enduring, though always modest, effort, the committee recommends that the program continue to be managed separately from programs responsible for current and near-term flight operations. Nevertheless, to ensure that relevant work is properly integrated, the EMC program must maintain close communication with the ALS program.

Crewmembers will be called on to perform useful work outside the confines of their pressurized spacecraft or planetary base. These activities are referred to as extravehicular activities (EVA). EVA has been a vital part of the U.S. space program since the Gemini program in the early 1960s. The spacesuit worn outside a spacecraft with its integrated life support system is called an extravehicular mobility unit (EMU). It must protect a crewmember from harsh environments characterized by the vacuum of space and solar radiation (with its attendant thermal loads). The EMU also provides some protection from ionizing radiation² and micrometeoroids. The EMU presents unique design challenges in that it is a miniature spacecraft that must simultaneously sustain and protect human life and

maximize productivity. The early suits used in the Mercury and Gemini programs were adaptations of pressure suits already in use by military aviators. The EMUs used in the subsequent Apollo and Space Shuttle programs were designed and built with specific characteristics tailored to their intended use. Future spacefaring activities will require EMUs with improved performance, safety, reliability, and maintainability.

Programs involving planetary (lunar/Mars) EVAs, with their attendant gravitational effects, will require capabilities that are beyond the current EMUs, which are designed for use in a weightless environment. Sustained EVAs in planetary conditions, which will occur far from access to resupply or other material support, will require EMUs designed for greater mobility and dexterity; reduced use of consumables; high reliability over long periods of time; reduced need for servicing; easier maintenance; increased resistance to dust; increased interchangeability and versatility; and reduced time for ''prebreathe'' for tissue denitrogenation (required to prevent decompression sickness, often colloquially referred to as "the bends") prior to performing an EVA. Research on advanced EMU technologies may also have present and near-term benefits.

Although the areas that require additional work are reasonably well understood, no specific, overarching technical objectives or milestones have been identified for the EVA program. The committee found a number of unprioritized projects being maintained at a basal level while awaiting a decision regarding the program's future course. As the duration of these projects increases, so do total costs. The lack of management direction has had a significant impact on the effectiveness of EVA technology development. Although the staff at NASA responsible for the EVA technical development is technically strong and competent, projects are sometimes conducted without adequate communication with the external engineering and scientific communities. More interaction with researchers external to NASA could leverage resources and improve the effectiveness of the R&D program.

The EVA Project Office, which was established at JSC during this study, appears to be in a position to provide direction and leadership for establishing long-term, advanced technical objectives and milestones. This office has outlined plans to increase contacts with the external technical and scientific communities and thus reduce the present insularity of the program. However, the funding dedicated to advanced technologies is small (about $2 million in FY96), and the committee was informed by program management that the first priority of the EVA Project Office is to enable present and near-term mission operations rather than to develop new technology for advanced EVA systems. This is understandable, especially considering the demands that will be associated with assembling the ISS. Nevertheless, both operational and research responsibilities will reside in the EVA Project Office, which will have to take particular care to ensure that near-term needs do not overwhelm the pursuit of a consistent, coordinated advanced EVA R&D program.

Human factors engineering is an essential ingredient of any space program involving humans. The discipline seeks to provide a working and living environment that will result in the greatest productivity and the highest probability of mission and task success. Human factors engineering is based on understanding the relationships between an individual (on a physical, cognitive, and social level) and the systems and environment with which he or she interacts.

Human factors research is being conducted at several NASA centers, but the OLMSA space human factors (SHF) program sponsors projects at just two centers, JSC and ARC. The program is small; the FY96 budget was approximately $1.5 million, and only about 8 to 10 peer-reviewed projects were funded by the program. Very little funding is available for NASA-led projects or initiatives based solely on the decisions of program management, which limits management's ability to respond in a timely manner to new issues as they arise. The stated goals of OLMSA's SHF program, as currently and vaguely defined, are to address human psychological and physiological capabilities and limitations, develop cost effective technologies that support human and system elements of space flight, and ensure that mission planners use the results of human factors research and technology developments to increase mission success and crew safety.

The nature of these goals makes it difficult to evaluate the success of the programs. Currently, SHF research at JSC is best characterized as mission-oriented and intended to address operational issues of immediate concern rather than issues related to long-duration space missions. Only a few formal priorities beyond support for current or near-term missions have been defined, and work is usually directly related to space operations. The projects at ARC are primarily related to aviation (especially cockpit issues) and more basic research. ARC also studies perception, workload, and cognition associated with aeronautical flight. Occasionally, specific crew-related problems serve as catalysts for investigations, and some interest was expressed in finding applications for ARC research beyond aeronautics in the field of space and elsewhere. There is little overlap in the research under way at the two centers, and there appears to be relatively little interaction among researchers from the two communities.

Current projects supported by the SHF program may prove to be helpful for future missions, but their benefit to long-duration missions seems more likely to be fortuitous than deliberate. At the time of the committee's review, no program requirements documents or detailed strategic or operational plans were in place, and no programmatic leadership was addressing the long-term issues.

Within OLMSA, the work related to human behavior and performance is managed separately from the SHF program. The committee believes that this separation creates an unnatural division between activities that should be integrated. The committee believes that the behavioral aspects of human space explo-

ration are crucial to the success of long-term missions but have not been thoroughly researched. This is important because behavioral issues related to long-term space exploration are not likely to be addressed outside of NASA. But, in areas where there is overlap, the SHF program should encourage interaction both within the agency and with outside academic, commercial, and government work in related areas. Effective interaction would leverage the results and would also help avoid the tendency to "reinvent the wheel."

Better communication and integration with other projects related to long-duration missions (e.g., ALS, EVA, training, safety, behavior, and performance) will be essential to crew safety and compatibility for lunar or Mars missions. The ISS should be used to study aspects of SHF, such as habitability, that must be incorporated into the design of future space vehicles (especially a Mars transfer vehicle) or planetary bases. The quality of research on SHF varies widely, and NASA would benefit considerably from better internal evaluations and periodic external reviews. Focused priorities—especially in areas where NASA has unique interests that are unlikely to be pursued by others—with clearly identified objectives, strong leadership and management, timely examination of technologies being developed elsewhere, and critical evaluations appear to be the ingredients necessary for future success.

The SHF program requires strong leadership with a view of the entire SHF area. The top NASA manager for SHF should have the experience and authority to coordinate disparate disciplines and entities and should be placed at a high level in the organization. Increasing the focus of the program while broadening the research base will be a challenge and will require a well orchestrated team effort.

Recommendation 1. During the period of the committee's study, the NASA Advanced Human Support Technology Program suffered from a lack of clear direction. This situation seems to arise from two basic conditions: (1) NASA has not directed research and development to address specific long-term goals in human space exploration, and (2) NASA has not decided who will lead the programs. NASA should establish a well-defined management structure for the human support programs and forthrightly communicate the new structure to NASA personnel. OLMSA should then proceed with programs directed at the unique needs for advanced human support technologies for crewed missions beyond low Earth orbit.

Recommendation 2. Requirements for technology development should be predicated on carefully developed reference missions and systems analyses to determine functional requirements. Good design reference mission studies exist that can be adapted and used by all programs. OLMSA should not expend significant resources to develop new reference missions.

Recommendation 3. It is clear that not all technology required to support human space exploration can be developed within the present annual funding levels (less than $20 million annually for all four OLMSA programs). As long as funding remains close to current levels, the committee believes programs must be narrowly focused and prioritized to address key technology needs. The roles and tasks of all groups (NASA and non-NASA) performing human support research and development sponsored by NASA should be clearly defined, and only projects that address the highest priority technology needs for future missions should be allocated program resources.

Recommendation 4. Systems analysis approaches should be included in ongoing and future processes to determine the highest priority technologies for human support in space.

Recommendation 5. Periodic NASA announcements calling for proposals from prospective researchers in topics related to human support in space should clearly identify the high priority areas in each program. The selection process should give added weight to proposals that are relevant to the high priority areas defined in the announcement.

Recommendation 6. Spin-off technologies should be transferred to applications outside of OLMSA as appropriate, but only as dividends from projects aimed at furthering NASA objectives. Technology transfer should not become a major emphasis of small technology development programs.

Recommendation 7. The International Space Station should be used as a site for research relevant to human support in space and for tests and demonstrations of new human support technologies.

Recommendation 8. The committee recognizes that NASA has unique technology needs, but technical insularity in the NASA human support programs is excessive. NASA should put more emphasis on finding technologies and knowledge relevant to human support outside of the NASA centers and the other locations where technology has been developed in the past. The human support programs should strive to include universities and large companies in their projects and should make special efforts to take advantage of the willingness of industry to use private funds for research and development projects relevant to NASA's long-term goals. Technical communication—inter-, intra-, and extra-NASA—including publication, should be expanded and actively supported.

NRC (National Research Council). 1997. Radiation Hazards to Crews of Interplanetary Missions: Biological Issues and Research Strategies. Committee on Space Biology and Medicine, Space Studies Board. Washington, D.C.: National Academy Press.