The draft roadmap for technology area (TA) 06, Human Health, Life Support, and Habitation Systems, consists of five level 2 technology subareas:1
• 6.1 Environmental Control and Life Support Systems and Habitation Systems
• 6.2 Extravehicular Activity Systems
• 6.3 Human Health and Performance2
• 6.4 Environmental Monitoring, Safety, and Emergency Response
• 6.5 Radiation
The draft NASA roadmap for TA06 includes technologies necessary for supporting human health and survival during space exploration missions. These missions can be short suborbital missions, extended microgravity missions, or missions to various destinations. These missions experience extreme environments with reduced gravity (less than 1 g); high levels of several types of radiation and ultraviolet light (space weather); vacuum or significantly reduced atmospheric pressures; micrometeoroids, and/or orbital debris. While many TA06 technology solutions will have broad application to designs used during transit to a number of destinations, assuming that transit is always at a microgravity level, destination environments could drive different functional requirements for surface missions. Designs that are independent of destination are worthwhile goals, but this can lead to design requirements with no feasible or cost-effective solutions. Also, human exploration missions to destinations beyond the Moon will not have early return or abort options, so testing and certifying systems in flight-like environments and developing certified models will be critical to mission success and safety.
The draft TA06 roadmap is divided into 20 level 3 technologies, which are subdivided into and 78 level 4 items. As with some of the other Tas, the level 3 “technologies” in TA06 typically have a broad scope that encompasses a variety of systems, subsystems, and components with multiple potential design solutions.
1The draft space technology roadmaps are available at http://www.nasa.gov/offices/oct/strategic_integration/technology_roadmap.html
2During the execution of this study, the NRC completed its report Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era (April 2011), which represents a more in-depth review of subject matter covered in TA06.3, Human Health and Performance
TABLE I.1 Technology Area Breakdown Structure for TA06, Human Health, Life Support, and Habitation Systems
|NASA Draft Roadmap (Revision 10)||Steering Committee-Recommended Changes|
|TA06 Human Health, Life Support, and Habitation Systems||One technology has been renamed.|
6.1. Environmental Control and Life Support Systems and Habitation Systems
6.1.1. Air Revitalization
6.1.2. Water Recovery and Management
6.1.3. Waste Management
6.2. Extravehicular Activity Systems
6.2.1. Pressure Garment
6.2.2. Portable Life Support System
6.2.3. Power, Avionics and Software
6.3. Human Health and Performance
6.3.1. Medical Diagnosis/Prognosis
6.3.2. Long-Duration Health
6.3.3. Behavioral Health and Performance
6.3.4. Human Factors and Performance
6.4. Environmental Monitoring, Safety and Emergency Response
6.4.1. Sensors: Air, Water, Microbial, etc.
6.4.2. Fire: Detection, Suppression
6.4.3. Protective Clothing/Breathing
6.5.1. Risk Assessment Modeling
6.5.2. Radiation Mitigation
6.5.3. Protection Systems
6.5.4. Space Weather Prediction
|Rename: 6.5.4. Radiation Prediction|
6.5.5. Monitoring Technology
Prior to prioritizing the level 3 technologies included in TA07, several technologies were renamed, deleted, or added. The changes are briefly explained below and illustrated in Table J.1. The complete, revised TABS for all 14 Tas is shown in Appendix B.
It was the consensus of the panel that technology topic 6.5.4., Space Weather, be removed from this roadmap and possibly identified as a separate interagency roadmap (for example, including NASA, NOAA, NSF, and DOD) outside the scope of Panel 4 and NASA. Level 3, 6.5.4, was then restructured and renamed “Human Radiation Prediction.” As described in the roadmap, this technology is focused on monitoring, modeling, and predicting ionizing radiation from solar particle events (SPEs) and galactic cosmic radiation (GCR). This radiation is a subset of space weather, which includes many other phenomena. The new name better describes the limited scope of this technology as applied to this roadmap.
TOP TECHNICAL CHALLENGES
The panel identified five top technical challenges for TA06, listed below in priority order.
1. Space Radiation Effects on Humans: Improve the understanding of space radiation effects on humans and develop radiation protection technologies to enable long-duration human missions.
Missions beyond low Earth orbit (LEO) present an expanded set of human health hazards. Lifetime radiation exposure is already a limiting flight assignment factor for career astronauts on the International Space Station
(ISS). Still, human health radiation models for predicting health risks are currently hampered by large uncertainties based on the lack of appropriate in situ data. At the present time, these models predict that crewed missions beyond LEO would be limited to 3 months or less because of adverse health impacts, either during the mission or during a crewmember’s lifetime. Without the collection of in situ biological data to support the development of appropriate models, as well as the development of new sensors, advanced dosimetry instruments and techniques, solar event prediction models, and radiation mitigating designs, extended human missions to the Moon, Mars, or near-Earth asteroids (NEAs) may be beyond acceptable risk limits for both human health and mission success. An integrated approach is needed to develop systems and materials to monitor radiation in near-real time and protect crewmembers. In order to implement these technologies, existing radiation protection technologies must be upgraded and new technologies deployed as needed so that the radiation environment is well characterized and solar events can be forecast from at least Earth to Mars. Game changers that will help address this technical challenge include decreased transit times through new propulsion systems to lower exposure; new materials for EVA suits, spacecraft, rovers, and habitats; and new ISRU capabilities to build protective habitats in situ.
2. Environmental Control and Life Support Closed Loop Systems: Develop reliable, closed-loop environmental control and life support systems (ECLSS) to enable long-duration human missions beyond low Earth orbit.
ECLSS for missions beyond Earth orbit (for spacesuits, spacecraft, and surface habitats) are critical for safety and mission success. It was a loss of an oxygen tank and subsequently a compromise of a portion of the ECLSS loop (CO2 removal) that nearly cost the Apollo 13 crew their lives. In missions without early return capability or remote safety depots, the ECLSS system must be as close to 100 percent reliable as possible and/or easily repairable with little or no resupply. Because air and liquid systems are sensitive to gravity level, extended testing of systems in reduced gravity may be necessary before they are integrated into exploration spacecraft. Current ISS experience with both U.S. and Russian ECLSS systems shows significant failure rates that would be unacceptable for an extended human exploration mission. In many cases, ISS ECLSS equipment has been launched and implemented without microgravity testing. Even with ISS testing, data on the performance of ECLSS systems in the reduced gravity of the Moon (~1/6 g) and Mars (~3/8 g) is not and will not be available without suitable reduced/variable-gravity test facilities. This will be a major impediment to maturing ECLSS technologies. New propulsion capabilities that reduce mission duration would reduce exposure to failures.
3. Long-Duration Health Effects: Minimize long-duration crew health effects.
The accumulated international experience with long-duration missions indicates that physical and behavioral health effects and adverse events will occur on long-term exploration missions. In some cases, health effects could be life threatening in the absence of effective diagnosis and treatment. Some of these health-related effects and events can be predicted and planned for, but it is highly likely that others cannot. In such a situation, autonomous, flexible, and adaptive technologies and systems will help promote long-duration health and effectively restore it when accident or illness occurs. Areas of interest include adverse effects of reduced gravity (such as bone loss, muscular and cardiovascular deconditioning, and neurovestibular disorders), in-flight surgery capability in reduced gravity, autonomous medical decision support and procedures management, and in-flight medical diagnosis enabled by a new generation of solid state, non-invasive, wireless biomedical sensors and “laboratory on a chip” technologies.
4. Fire Safety: Assure fire safety (detection and suppression) in human-rated vehicles and habitats in reduced gravity.
Current fire safety technologies for 1 g and microgravity environments are well understood and have an excellent history for longevity as will be needed for future human exploration missions beyond LEO. However, the space shuttle experience included two cases where smoldering electrical fires were detected by crew members working in close proximity to the problem and not by electronic sensors. Also, Russia’s Mir space station experienced a fire
in its oxygen-generating candle system that proved difficult to extinguish and required several days to achieve full recovery. Microgravity fire suppression systems currently use water or CO2 as the extinguishing agent. Dumping large amounts of CO2 into a small cabin environment is hazardous to the crew and puts significant strain on the ECLSS to remove the excess CO2. Using water as the extinguishing does not pose a crew hazard but does have a significant impact on mission mass. Research and testing are needed to understand why current sensors failed to detect a smoldering electrical fire, develop more efficient and less hazardous fire suppression systems, and develop remediation capabilities that do not impair ECLSS components and/or processes.
5. EVA Surface Mobility: Improve human mobility during extravehicular activity (EVA) in reduced gravity environments (0 g up to 3/8 g) in order to assure mission success and safety.
Two closely related versions of space suits were used during the Apollo lunar missions; relatively little supported research has taken place on suits for environments other than microgravity in the intervening four decades. In the interim, experience with EVA during the Space Shuttle Program focused primarily on modifications for maintainability and on-orbit resizing; the only major advances in pressure garment mobility during that time was in the development of more dexterous pressure gloves. Differences in Apollo and future planetary suits will include the effects of long-term exposure to microgravity en route, prior to reduced gravity EVA operations for surface durations many times that of the 3 days in J-class Apollo missions. Apollo suits were further restricted by the mandate that they also be suitable for launch and entry use, but the Space Shuttle Program demonstrated the utility of separating the launch and entry function from EVA operations. Critical issues for research in this area include the effects of reduced gravity levels— at least lunar (1/6 g) and martian (3/8 g)— on gait, posture, and suited biomechanics; the use of advanced materials and techniques for extending life, enabling ease of maintenance, and reducing the effect of surface dust on bearings, seals, and closure mechanisms. Operationally there are substantial benefits from thorough integration of rovers, pressurized habitats, and robotic assist vehicles in extended surface operations: these need to be further researched to provide a sufficient database to make quantitative trade-offs for specific mission objectives. Finally, innovative technologies providing sensory, data management, and actuation assistance to the suit wearer must be developed and assessed for potential augmentation of future human EVA system architectures.
QFD MATRIX AND NUMERICAL RESULTS FOR TA06
Figure 1.1 summarizes the consensus scores of the 20 level 3 technologies in NASA’s draft roadmap for TA06. The panel evaluated each of these to level 4, based on the description of level 4 items in the roadmap because this was the only level to which TRLs were assigned. The scores shown below for each technology reflect the highest priority level 4 items within each level 3 technology. For the high-priority level 3 technologies (see Figure I.2), key level 4 items are discussed in the section below that covers high-priority technologies.
Figure I.2 plots the overall rankings for each level 3 technology. The panel assessed 14 of the technologies as high priority. Twelve of these were selected based on their QFD scores, which significantly exceeded the scores of lower ranked technologies. After careful consideration, the panel also designated two additional technologies as high-priority technologies.3 The quanitity of “high-priority” topics can be misleading because the 14 high-priority level 3 technologies actually break down into five high-priority theme areas: Radiation, ECLSS/Habitation, Human Health/Performance, EVA Systems, and Envrionmental Monitoring/Safety (EMS).
Nine of the 14 high-priority technologies are in the radiation or life support (ECLSS/Habitation) theme areas, which are the most critical for crew survival beyond Earth orbit.
3In recognition that the QFD process could not accurately quantify all of the attributes of a given technology, after the QFD scores were compiled, the study panels in some cases designated technologies as high priority even if their scores were not comparable to the scores of the other high-priority technologies. The justification for the high-priority designation of all the high-priority technologies appears in the section “High Priority Level 3 Technologies,” below
FIGURE I.1 Quality function deployment (QFD) summary matrix for TA06 Human Health, Life Support, and Habitation Systems. The justification for the high-priority designation of all high-priority technologies appears in the section “High-Priority Level 3 Technologies.” H = High Priority; H* = High Priority, QFD score override; M = Medium Priority; L = Low Priority.
FIGURE I.2 Quality function deployment rankings for TA06 Human Health, Life Support and Habitation Systems.
CHALLENGES VERSUS TECHNOLOGIES
Figure I.3 shows the relationship between the individual level 3 TA04 technologies and the top technical challenges. In general, the mapping validates the major focus areas.
HIGH-PRIORITY LEVEL 3 TECHNOLOGIES
Panel 4 identified 14 high-priority technologies in TA06, grouped into five high-priority theme areas: Radiation, ECLSS/Habitation (life support), Human Health/Performance, EVA Systems, and Environmental Monitoring/Safety (fire safety). The justification for ranking each of these technologies as a high priority is discussed below.
Space radiation poses a grave risk to human health for long-duration space missions (NRC, 2008). Thus, the high-priority technologies for TA06 include five level 3 technologies related to radiation, as follows:
• 6.5.5. Radiation Monitoring Technology: Measuring the exposure
• 6.5.3. Radiation Protection Systems: Reducing the exposure (shielding)
• 6.5.1. Radiation Risk Assessment Modeling: Understanding the effects of radiation
• 6.5.4. Radiation Prediction: Forecasting radiation exposure
• 6.5.2. Radiation Mitigation: Reducing the impacts of exposure (countermeasures)
Technology 6.5.5, Radiation Monitoring Technology
The ability to monitor the local radiation environment at and even within the crew members on long-duration space missions will be critical to ensure human health and mission success. This technology specifically addresses the need to measure and report on the ionizing particle environment (including neutrons) wherever humans may travel beyond Earth orbit (including the surface of the Moon and Mars, during unshielded EVAs and inside shielded vehicles and habitats). Measuring the local radiation environment, including the secondary radiation generated in the shielding, is necessary to ensure that astronauts keep their total exposure “as low as reasonably achievable” (a key tenet of radiation safety practices). Passive radiation monitors have been employed by NASA throughout its history of human spaceflight. However, established technologies are not sensitive to the full range of radiation that will be encountered beyond Earth orbit, nor do they give details about the types of particles contributing to the indicated dose. This is important because the most recent assessment of known radiation exposure for astronauts would limit them to approximately 90 days of exposure during missions outside of Earth orbit. This would preclude Mars and NEA missions without some revolutionary advance in in-space propulsion capabilities.
Advances are needed for small, low-power dosimeters with active readout that can sense and distinguish among a broad range of radiation, especially neutron dose and dose rate. In addition, NASA may be introducing a new approach to estimate the biological effectiveness of radiation which may call for a new family of dosimeters (see discussion below on technology 6.5.1, Radiation Risk Assessment. The current paradigm is based on the notion that biological impact is largely due to the distribution of energy deposited as a particle moves through the body. Thus, different particles that deposit energy at the same rate would have similar impacts. A new paradigm gaining favor proposes that both the energy and charge distribution of the particles impacting the body affect human health. Current dosimeters do not provide this type of information. Another area of technology development relates to biodosimetry: non-invasive means of measuring the dose and dose rate inside the human body. One example is to analyze blood samples, perhaps without even drawing blood.
Traditional dosimeters currently in use are at TRL 9. Improved versions that are lower power and provide better active readout exist in the TRL range of 4 to 6, and next generation dosimeters and biodosimeters to meet the requirements of long-duration spaceflight are just now emerging with TRLs 1 to 3.
While NASA needs dosimeters sensitive to a unique radiation environment, improvements in active dosimeters may have applications beyond NASA. Examples include radiological medicine, miners exposed to radioactive
FIGURE I.3 Level of support that the technologies provide to the top technical challenges for TA06 Human Health, Life Support, and Habitation Systems.
minerals, monitoring nuclear power plants and surrounding areas (both during routine operation and during emergency contingencies), commercial airlines, and first responders dealing with radiological emergencies.
The ISS has been and will continue to be a significant testbed for improved radiation monitors. Testing on the ISS enables cross calibration with dosimeters that have been used for decades in a realistic and well-characterized work environment. However, the radiation environment in deep space is different than in LEO, where Earth’s magnetosphere provides some protection. To better characterize the deep space radiation environment, inert and biological-based sensors should be sent to higher orbits, lunar-Earth Lagrange points, or the lunar surface.
Technology 6.5.3, Radiation Protection Systems
Radiation protection systems include materials and other approaches to limit astronauts’ radiation exposure. This technology complements 6.5.2, Radiation Mitigation, which addresses physiological countermeasures to alleviate the impact of radiation exposure, and it may benefit from advanced materials developed by other roadmaps. Although discrete technology options were not provided in the draft TA06 roadmap for radiation protection systems, and even though the earliest start date for this technology suggested in the roadmap was 2014, the panel endorses near-term investments in this technology.
Shielding is a critical design criterion for many elements of human exploration, including deep space transport vehicles, surface habitats, surface rovers, EVA suits, and other transportation elements. Shielding alone is unlikely to eliminate radiation exposure from GCR (including secondary exposure), but a well-shielded vehicle or habitat could substantially reduce the exposure from SPEs.
It may also be possible be to emulate the electromagnetic field in Earth’s magnetosphere. This has been suggested as an attribute to the advanced Variable Specific Impulse Magnetoplasma Rocket (VASIMR), which will be tested on the ISS within the next 3 years. The essential challenge is to reduce radiation exposure while meeting overall mission allowances for mass, cost, and other design considerations. A comprehensive radiation mitigation strategy will also address the need for adequate SPE warning and detection (technologies 6.5.4 and 6.5.5) so that astronauts can take shelter in a timely fashion.
Advanced radiation protection technology is at low TRL (~1-3). Low-atomic-number (low z) elements (such as hydrogen) provide better shielding from particle radiation than high z elements (such as heavy metals). Thus, water and polyethylene, which contains a lot of hydrogen atoms, are effective shielding materials. Recent research has been exploring multifunctional composites that would have structural and shielding properties suitable for incorporation directly into spacecraft structures. Advanced composites of interest include hydrogen-loaded carbon or boron nitrate nanotubes for multilayer coatings or components. These approaches are at low TRL.
Developments required for progress in this technology include the following:
• Identify advanced shielding materials and approaches.
• Advance the TRL of promising materials.
• Integrate shielding approaches into spacecraft and habitat design and operations concepts.
• Explore innovative shielding techniques, including active shielding concepts (magnetic shields).
NASA would benefit from improved radiation shielding concepts that reduce the radiation risk to astronauts, potentially at lower mass, and thus at lower mission cost. This effort could provide a new materials for incorporation across a wide range of human exploration mission architectures. Improved integration of shielding concepts early in the design process will enhance the mission design process.
The ISS has been and will continue to be a significant testbed for improved shielding material. Concepts can be deployed and tested in realistic conditions, including, where necessary, outside the station for durability testing in the space environment. However, because of the shielding effects of Earth’s magnetosphere, certification testing for exploration missions beyond LEO may require testing in higher orbits, at lunar-Earth Lagrange points, or on the lunar surface.
While shielding against GCR and SPEs is a uniquely NASA requirement, advanced radiation shielding materials and approaches could have terrestrial applications, for example, for shielding in nuclear power plants, high-altitude aircraft, radiation medicine, and in radioactive contingency response against terrorist threats.
Technology 6.5.1, Radiation Risk Assessment Modeling
The major contributor to estimated mission dose is from highly penetrating GCR. Additional exposure is possible from periodic, intense episodes of solar activity known as SPEs. While reasonable shielding can significantly limit SPE exposure, shielding is largely ineffective at reducing the GCR risk.
There are several layers of risk limits included in NASA’s permissible exposure limits. The major mission constraint is to limit the astronauts “risk of exposure induced death” (REID) from cancer to no more than 3 percent at the 95 percent confidence level. This risk limit is dominated by a significant uncertainty in quantifying the radiation impacts. It is estimated that the uncertainties in the cancer REID is about a factor of 3.5. There are no quantifiable limits to radiation impacts on the central nervous system, the cardiovascular system, and the immune system. However, it is believed that the cancer risk to these organs can be limited by maintaining whole body radiation dose within established limits, which are higher for professional astronauts than for the general public. The commercial spaceflight industry will need to carefully evaluate acceptable passenger exposure levels, provide appropriate protection, and seek federal approval to increase radiation dose limits for “space tourists, ” if necessary.
Doubling the nominal shielding reduces the GCR-induced dose by only 15 to 20 percent, and reducing the cancer uncertainty by fifty percent could require increasing the shielding by up to a factor of five. Reducing biological and other 50 about radiation health risks is needed to quantify the value of alternative shielding (see 6.5.3, Radiation Protection Systems) and the efficacy of possible countermeasures (see 6.5.2, Radiation Mitigation). Attaining this reduction will require continuation or expansion of a substantial research program that includes data collection in space; ground-based fundamental research, data analysis, and technology development; and in-space validation of new models in micro- and reduced-gravity environments to explore the synergistic effects of various g--levels. The ISS can contribute to the validation of risk models, but this would require the development of appropriate systems, such as the bioreactor and other facilities. Final validation may require lunar surface facilities which can be periodically accessed.
No other agencies or organizations have the responsibility to understand the impacts of the unique space radiation environment on human health, and NASA research in this area could make substantial contributions to understanding fundamental aspects of radiation’s role in carcinogenesis. In addition, the techniques developed for the risk assessment methodology could have broad applicability to terrestrial occupational and environmental health.
Technology 6.5.4, Human Radiation Prediction
The ability to forecast the radiation environment will be critical to ensure the safety of astronauts and mission success. This technology specifically addresses the need to forecast SPEs, which are periods of intense ionizing radiation associated with solar storms. A related technology area, 6.5.5, Radiation Monitoring Technology (see above), addresses the requirement to measure the local radiation environments.
There is no capability to forecast the onset of SPEs, and only limited ability to forecast the evolution of an SPE once it is underway. Today, the strategy to manage the risks associated with SPEs can be categorized as “cope and avoid,” meaning that conservative flight rules are developed that enable astronauts to quickly take shelter in a shielded segment of a spacecraft or habitat after observing the onset of an SPE. This has several drawbacks: it limits the time astronauts can prepare for an event, it restricts exploration timelines to stay within a narrow response window, and it leads to over-reaction to small events or false alarms. All of this overly constrains mission operations. In addition, it leaves astronauts susceptible to an unusually severe event that surprises a crew, with potentially severe health risks.
Developments required for progress in this technology include the following:
• Improve understanding of the physics of SPEs.
• Develop better applied models for forecasting the timing and impacts of SPEs.
• Develop advanced dosimetry to more accurately measure the natural radiation environment in locations that are or will be frequented by astronauts (especially the very highest energy particles, hundreds of MeV). (See technology 6.5.5. Radiation Monitoring Technology.)
• Develop lighter instruments and satellites to enable the deployment of a cost-effective radiation monitoring architecture.
• Develop more efficient communication systems to relay data from disparate monitors around the solar system.
The implementation of an improved SPE forecast system (including physics-based forecasts of 8- to 24-hour “all clear periods”) would improve mission effectiveness and enable more cost effective mitigation strategies by giving astronauts more time to respond, by reducing the time they spend under shelter, and by reducing or eliminating false alarms.
Monitoring the radiation environment near, but external to, the ISS would contribute to models that attempt to understand the dynamic response of Earth’s magnetosphere to the complex series of events that occur during major SPEs. In particular, it helps identify the extent to which the intensity of high-energy particles extends to mid to low latitudes, increasing the radiation exposure to spacecraft in low Earth orbit with medium to low inclination.
No other agency has the need or responsibility to forecast the intensity or nature of SPEs except in the neighborhood of Earth. However, if NASA succeeds in implementing an effective strategy to forecast SPEs throughout the inner solar system (to support missions to Mars or NEAs) then it will benefit forecasts of events that affect Earth.
This technology will have a significant benefit, as the impact of SPEs goes far beyond astronaut health: the high-energy particles in a SPE can damage or degrade instruments and other equipment on satellites of all types, including communications, navigation, and remote sensing satellites. This technology will also support the emerging commercial spaceflight industry and aviation, particularly for flights at high latitude. Polar routes have increased substantially in the past 10 years. During SPEs, it may be prudent for aircraft on polar routes to fly at reduced, less economical altitudes or diverted to alternate routes or destinations to avoid the effects of SPE interference with polar communication networks. Accurate forecasts would improve flight planning and could avoid mid-flight corrections.
Technology 6.5.2, Radiation Mitigation
Radiation Mitigation addresses countermeasures to alleviate the impact of radiation exposure. This technology area complements 6.5.3, Radiation Protection Systems, which includes shielding and other approaches to reduce astronauts’ radiation exposure. It is generally considered that shielding alone will not eliminate GCR exposure; especially on spacecraft where mass is at a premium. (ISRU technologies may be able to provide substantially better shielding on surface habitats using in situ materials.) In any case, exploring biological and/or pharmacological countermeasures may be able to mitigate the effects of continuous, long-term radiation exposure. In addition, in spite of best intentions and careful planning, an astronaut could still be exposed to a significant dose of radiation during an SPE. In such an event, medical measures to limit the severity of acute radiation effects could be invaluable. Unfortunately, at present there are few pharmacological countermeasures to acute doses of radiation. Also, these countermeasures were developed for use after nuclear emergencies, and it is assumed that they would be provided in conjunction with extensive medical care. The side effects of these countermeasures may limit their usefulness in space. Also, there are no effective countermeasures to chronic GCR exposure.
It is not likely that countermeasures designed to mitigate one radiation endpoint (say, carcinogenesis) will be effective against another (degeneration of the cardiovascular system). Diets rich in antioxidants can reduce some radiation effects, but the full efficacy of such as diet has not been quantified for various types and levels of radiation exposure. In fact, it may be difficult or impossible to quantify accurately the value of countermeasures before the uncertainty in radiation levels and the health impacts of that radiation has been reduced (see technology 6.5.1, Radiation Risk Assessment Modeling). Countermeasures are still at low TRLs (1 to 3).
Developments required for progress in this technology include the following:
• Identify potential countermeasures to specific radiation-induced adverse health effects.
• Conduct appropriate clinical studies to prove efficacy.
• Explore synergistic effects of multiple countermeasures.
• Increase the TRL of effective countermeasures.
NASA would benefit from improved radiation countermeasure concepts by reducing the radiation risk to astronauts, by enabling longer missions, and provide protection from accidental exposure to acute doses of radiation.
The ISS has been and will continue to be a significant test bed for countermeasure studies. Concepts can be deployed and tested under realistic conditions, especially to confirm the lack of side effects or unintended consequences.
While countermeasures against GCR and SPEs are a uniquely NASA requirement, some radiation mitigation techniques could likely be used in broader terrestrial applications, such as response to nuclear power plants emergencies, high-altitude aircraft, radiation medicine, and in response to terrorist threats.
The ECLSS/Habitation theme area has four high-priority technologies:
• 6.1.4. Habitation: Includes food production and processing as well as hygiene.
• 6.1.3. Waste Management: Includes liquid and solid waste.
• 6.1.2. Water Recovery and Management: Provides recycling for long missions.
• 6.1.1. Air Revitalization: Removes CO2, particulates, and contaminants, and provides thermal control.
As shown in Figures I.1 and I.2, these four technologies received approximately the same QFD scores.
Technology 6.1.4, Habitation
The habitation technology is focused on functions that closely interface with life support systems. The level 4 items in this technology are as follows: food production (126.96.36.199), food preparation/processing (188.8.131.52), crew hygiene (184.108.40.206), metabolic waste collection and stabilization (220.127.116.11), clothing/laundry (18.104.22.168), and re-use/recycling of logistics trash (22.214.171.124). This technology is predicated on and provides necessary functions for human spaceflight. It provides food, sanitation, comfort, and protection for space-faring crew members.
While a portion of this technology, such as crew hygiene and waste collection and stabilization, are at TRL 9, other activities such as food production, food preparation, and trash recycling are TRL 6, at most. The clothing and laundry area is a mix, as clothing is at a TRL 9, while laundry is at a TRL 4.
This technology would directly support human spaceflight for the complete range of missions lasting from several hours to months, such as long-duration stays on the ISS, or long-duration exploration missions to Mars or an NEA. The ISS is the ultimate test platform for this technology. It would allow habitation technology to ultimately be offered for use in other applications such as commercial human spaceflight. NASA involvement in the development of habitation technology is critical; without NASA involvement there will be no new habitation development, and it is essential to NASA for long-duration human spaceflight missions. There is no reason for NASA to partner with other federal agencies to develop this technology.
The use of the ISS would prove valuable in maturing the habitation technologies, increasing their reliability, and providing a means to demonstrate their functional performance. A good example would be the development of a plastic waste melt compactor, in which plastic trash and other trash material is melted and compacted to form a tile that can be used for radiation protection. As part of this technology, the effectiveness such tiles for radiation shielding could be tested Food production technology could also benefit from using the ISS as a test bed for scientific plant growth and for testing food production systems.
Habitation technology is a high priority because additional work is needed to advance from current LEO missions to long-duration missions beyond LEO. Food production would provide significant mass savings for such missions, augment life support systems, and provide psychological crew benefits. Food processing would allow a safe means for a crew to consume the food that is produced, reducing the likelihood of food borne illnesses and increasing crew health. The recycling of logistics trash converts otherwise disposed material into useful products to increase crew safety and/or capabilities.
Technology 6.1.3, ECLSS Waste Management
Waste management technology safeguards crew health, increases safety and performance, recovers resources, and protects planetary surfaces. This technology includes disposal, storage, and resource recovery from trash and crew waste. Key areas of concern include volume reduction, stabilization, odor control, and recovery of water, oxygen and other gases, and minerals.
Current ISS technology for trash disposal is very basic, and involves crew effort and duct tape. Feces disposal, stabilization, and odor control systems on the ISS have considerable spaceflight heritage and are at TRL 9. Still, there is room for continuous improvement. Automated trash compaction and resource recovery of spaceflight waste are in the early stages of development.
NASA has been developing and funding development of automated trash compaction and water recovery. NASA has the expertise, capabilities, and facilities to further develop these capabilities and to advance waste stabilization and recovery of additional resources. NASA spaceflight may be the only application for the compaction and resource recovery capabilities that must be developed, but other government and industrial organizations may be interested in waste stabilization.
The ISS is the ideal test bed for advanced waste management. EXPRESS Racks could be used for early technology development test beds, and successful technology could then undergo long-term testing on the ISS before they are adopted for a long-duration human exploration mission.
Resource recovery from waste is vital to closing the loop for long-duration human spaceflight. Until dumping large amounts of trash overboard is generally accepted, stabilization and volume reduction of trash is necessary to maintain safe and comfortable living conditions for crews on long-duration missions. As long as long-duration spaceflight is a goal, effective waste management must also be a goal. Trash stabilization, volume reduction, and water recovery are already showing promise in their early development, but more effort is needed to mature these technologies. Recovery of additional resources, such as O2, CO2, N2, and minerals from trash and human waste may require hardware with significant mass, power, and volume requirements, and a considerable amount of development may be needed until there is an equivalent system mass advantage to recovering these resources from waste, even for long-duration missions.
Technology 6.1.2, ECLSS Water Recovery and Management
This technology provides a safe and reliable supply of potable water to meet crew consumption and operational needs. Water recovery from wastewater is essential for long-duration transit missions due to the tremendous launch mass of water that would be required for an entire transit mission without recycling, and the impracticality of resupply from Earth. Both short-duration and long-duration missions require some degree of wastewater stabilization to protect equipment and facilitate potable water disinfection for storage.
Primary water recovery from urine, hygiene water, and humidity condensate is currently performed on the ISS and is at TRL 9. This technology needs additional development to improve reliability for long-duration missions where resupply from Earth is not possible. Primary water processers recover approximately 90 percent of usable water from a wastewater stream and expel the remaining 10 percent as waste brine. Technologies to recover water from wastewater brines are in the early stages of development, and are challenged by resource limitations, odor requirements, and the urine pretreatment chemicals that make brines acidic, corrosive, and sticky.
NASA has experience with primary wastewater processors and has been funding development of technologies to recover water from wastewater brines and alternatives to the current urine pretreatment methods that use sulfuric acid and an oxidizing agent. NASA has the expertise, capabilities, and facilities to continue development of these technologies. The demands and limitations for water recovery for long-duration missions are unlike those of any other industrial or government need. It is likely that NASA will pursue these developments independent of any other organization for the foreseeable future.
The ISS is the ideal test bed for this technology, as operation in microgravity is one of the primary challenges of any liquid processing technology. EXPRESS Racks could be used for early technology development test beds, and new technology could be used on the ISS long term before committing to transit missions.
Long-duration transit missions will not be possible without recovering water from wastewater. The importance of water recovery increases as the mission’s length increases. Even the difference between 98 percent recovery and 99 percent recovery has a tremendous impact on launch mass for a mission with a duration of several years with no resupply. Achieving 99 percent recovery would be difficult, but it is achievable with a coordinated effort among wastewater treatment, primary water processor, and brine processor development. An integrated approach is essential because each step in the water recovery process impacts downstream steps.
Technology 6.1.1, Air Revitalization
Air Revitalization (6.1.1) includes carbon dioxide removal, carbon dioxide reduction, oxygen supply, gaseous trace contaminant removal, particulate removal, temperature control, humidity removal, and ventilation. Several systems that provide one or more of these functions currently operate on the ISS; they are at TRL 9. The major shortcoming with the current state of the art of air revitalization technology is in carbon dioxide reduction. The ability to recover oxygen from waste carbon dioxide will be very important to reduce mass requirements for long-duration human exploration missions. To date, various technologies are being demonstrated in the laboratory, but none have yet been packaged or tested for flight. Other key objectives for this technology include reducing overall system mass and power consumption and decreasing acoustic emissions. A far-reaching goal is to use plants as a way to provide significant air revitalization functions. This has been demonstrated to varying degrees of success in the laboratory, but not in space. To do so would require developing a large amount of support equipment.
NASA has experience with every aspect of this technology and has been funding research in areas with low maturity for some time. NASA has the expertise, capabilities, and facilities to continue development of these technologies. The demands and limitations for revitalizing air for long-duration missions are unlike those of any other industrial or government need. It is likely that NASA will pursue these developments independent of any other organization for the foreseeable future.
The ISS is the ideal test bed for this technology, as operation in microgravity is one of the primary challenges of life support equipment. EXPRESS Racks could be used for early technology development test beds, and new technology could be used on the ISS long term before committing to transit missions. Attaching a larger structure, such as an inflatable module, to the ISS as a technology test bed would enable the use of the ISS on a larger scale.
Long-duration missions will not be possible without robust and comprehensive air revitalization capabilities, especially carbon dioxide reduction or some element of a hybrid physicochemical and/or biological air revitalization architecture for long-term sustainability. The difference between 50 percent oxygen recovery and 75 percent to 100 percent oxygen recovery has a tremendous impact on launch mass for a mission that must last several years with no resupply. The required development effort would be difficult, but achievable with a coordinated effort between the NASA centers and advanced air revitalization system providers, including physicochemical and biological.
The human health/performance theme area has one high-priority technology:
• 6.3.2. Long-Duration Health
Technology 6.3.2, Long-Duration Health
As stated in the roadmap, the focus of technology 6.3.2, Long-Duration Health, is to create “validated technologies for medical practice to address the effects of the space environment on human systems.” The accumulated international experience with long-duration missions to date (in LEO) reveals and predicts a simple, compelling truth about future exploration-class crewed missions: physical and behavioral health effects and adverse events will occur. Some of these health-related effects and events can be predicted and planned for, but it is highly likely that others cannot. Thus, autonomous, flexible, and adaptive systems to promote long-duration health, and effectively
restore it when accident or illness occurs, are a high priority. This determination is consistent with the findings of a series of prior Academy studies, including Safe Passage: Astronaut Care for Exploration Missions (2001), Review of NASA’s Longitudinal Study of Astronaut Health (2004), A Risk Reduction Strategy for Human Exploration of Space: A Review of NASA’s Bioastronautics Roadmap (2006), Managing Space Radiation Risk in the New Era of Space Exploration (2008) and Review of NASA’s Human Research Program Evidence Books (2008).
The panel identified artificial gravity evaluation/implementation as a game-changing capability that would greatly mitigate many adverse health effects that would otherwise occur during long-duration habitation in transit (or Earth orbit). These adverse effects include bone loss, muscular and cardiovascular deconditioning, and neurovestibular disorders. However, the prospect of a rotating a space station or exploration vehicle to produce 1 g or a significant fraction thereof seems unattainable in the time frame envisioned in the technology roadmap. Thus, the ability to generate artificial gravity using a facility such as a large centrifuge on the ISS would be a high priority if it could be achieved. Such a facility would enable research and testing on small mammals and other biological and spaceflight systems in trying to understand the effects of reduced gravity on humans, other biological systems, and spaceflight systems.
Maintaining human health on long-duration human exploration missions would be greatly facilitated by advances in this technology. The panel would place the highest priority on developing in-flight surgery capability in microgravity environments (126.96.36.199), autonomous medical records, informatics, and procedures management (188.8.131.52), and in-flight medical diagnosis (184.108.40.206). These capabilities are essential and require solutions that are highly tailored to the space environment. Trauma is the most highly prevalent medical issue in long-duration flight, and the ability to perform life-saving surgery after major trauma and other unpredictable life threatening conditions (e.g., appendicitis) will be very important for exploration class missions to improve crew survivability. Compact, low-mass imaging technologies (220.127.116.11) will support precise anatomic diagnosis and could potentially spur development of similar health technologies for healthcare on Earth. Similarly, a new generation of solid state, non-invasive, wireless biomedical sensors (18.104.22.168) to monitor physiologic processes could be catalytic for all forms of in-flight monitoring, disease prediction, diagnosis, and treatment monitoring. It might also lead to dramatic improvements in home monitoring of chronic health conditions worldwide. A highly reliable low mass “clinical laboratory on a chip” (22.214.171.124) could dramatically expand diagnostic and care possibilities. Countermeasures (126.96.36.199, 188.8.131.52), including technology advances for exercise-based approaches to mitigating physiologic deconditioning, as well as pharmacologic countermeasures will be very important for maintaining crew health during long-duration missions. The Advanced Test Platform (184.108.40.206) will be required to develop and assess various approaches to countermeasures. For each of the high-priority technologies noted above, the ISS will be a critical technology evaluation platform.
The EVA Systems theme area has two high-priority technologies:
• 6.2.1. Pressure Garment: Provides an advanced EVA suit.
• 6.2.2. Portable Life Support System: Contains many of the same components of the ECLSS for a spacecraft.
Technology 6.2.1, Pressure Garment
Pressure garments constitute the anthropomorphic articulated spacecraft in which each EVA crew member works and survives. The ideal pressure garment is easy to don and doff, highly articulated and readily adjustable to the kinematics of the wearer’s body, and minimizes additional forces and torques which the wearer must overcome to accomplish all tasks.
Space shuttle EMUs and Apollo A7L and A7L-B suits represent TRL 9 technologies. While they provide adequate functionality at pressures of 4.3 and 3.5 psi (respectively), substantial fractions of crew physiological workload (estimated variously between 40 percent and 75 percent) go into moving the pressurized suit joints.
Advanced suits are functional in laboratory and field situations (TRL 4-5), with near-term plans for neutral buoyancy and vacuum chamber testing given sufficient development funding.
While there are some applications of pressure garment technology outside of NASA, such as HAZMAT suits and biowar garments for the military, it is clear that no progress will be made in this field without significant and ongoing research support from NASA. NASA has retained a basic research and development capability in pressure garments throughout the shuttle program at the Johnson Space Center and at a small number of industrial suppliers; there was in the past a vibrant community of EVA researchers in academia and smaller companies, but this community has been largely starved to death over the past decade. A significant and sustained program of research and development will be required to create the next generation of extravehicular suit, whether for microgravity missions such as near-Earth objects, or for reduced gravity operations on the Moon or Mars.
The ISS represents the obvious location for the first flight tests of new pressure garment technologies, with benefits to enhanced crew performance for ISS maintenance tasks. At the same time, the real test of future pressure suits will be in their ability to support prolonged legged locomotion in the reduced-gravity environment of the Moon and Mars, and ISS testing will not validate this critical functionality.
EVA pressure garments are pivotal to all aspects of human spaceflight. They are required for protection against cabin depressurization for launch and entry, and for extravehicular activities in any class of human missions. While Apollo-era suits were a compromise between these two categories of use, future programs will almost certainly require (as did the Space Shuttle Program) specialized garments for the launch and entry and the extravehicular roles. While pressure suits have been included on every single human mission since Alan Shepard’s flight, the current operational technology represents incremental changes to the shuttle extravehicular mobility unit (EMU), which was developed more than 30 years ago. Thus, significant potential exists for substantial increases in performance and operational capabilities as compared to the current state of the art.
Modeling and analysis have advanced considerably since the development of the EMU; modern capabilities in biomechanical modeling and fundamental understanding of the behavior of pressurized fabric structures will provide a rigorous foundation for future pressure garment development. In parallel, current and upcoming materials, including “smart” materials with integrated sensors, controls, and even actuators will provide enhanced suit functionality. However, the primary focus of next-generation pressure garments must be on enhanced mobility. While specific estimates vary based on testing protocols and measurement techniques, there is widespread agreement that the space suit wearer requires a substantial fraction of their physiological workload for simply moving the pressure garments. Fatigue is a defining issue for procedures development and EVA planning, particularly in the hands and wrists for heavily dexterous activities. Advanced approaches which can improve the state-of-the-art in pressure garment mobility closer to nude-body performance will substantially reduce EVA crew workload, and subsequently expand the range of potential EVA applications in future space missions.
Note that the technologies for a launch and entry pressure garment are essentially mature, unless there is an operational requirement to use that suit for nominal or contingency EVA. In that case, the suit would need to be designed largely as an EVA suit capable of use for launch and entry (as in Apollo), rather than as a launch and entry suit which does EVA on the side.
Technology 6.2.2, EVA Portable Life Support Systems
The panel overrode the QFD scores and designated this technology a high priority because two level 4 topics were felt to be of critical importance and, despite low scores (since they are not critical to basic functionality, and all personal life support system (PLSS) functions are limited in non-spaceflight applications), both thermal control and CO2 capture were assigned high priority for special attention in future research funding decisions.
The current thermal control system (TRL 9) is based on water sublimation, which increases consumables usage and is not feasible in atmospheres, even the tenuous atmosphere of Mars. Heat sink approaches are typically massive, and required radiator area makes that approach infeasible for pressure suits. CO2 capture in PLSS applications is currently performed by expendable LiOH canisters or rechargeable metal oxide canisters, which require significant mass, volume, and power for recharging ovens to drive out the captured CO2.
Advanced portable life support systems are applicable to firefighters, hazmat suits, bio-warfare gear, and underwater breathing systems. The particular focus for NASA technology development (in terms of thermal control without sublimation and extremely high-reliability systems where cost is relatively unimportant) is unique to the NASA mission.
Initial flight testing of advanced PLSS technologies is well performed at the ISS, and could represent significant increase to ISS EVA capabilities. Challenges for future PLSS systems, such as thermal control in the martian atmosphere or extended functionality in the dusty environment of surface exploration, are not well represented by ISS testing.
Increasing the capacity, reliability, and maintainability of a PLSS while extending duration and reducing on-back weight for the user are important, but difficult goals.
The greatest challenge in this technology area is in environmental effects on the PLSS systems. These include the effects of low but discernible atmospheric pressure on Mars, long-term effects of dust on all solar systems bodies from asteroids to the Moon and Mars, and charging effects in geostationary orbit. The PLSS must be designed as an integrated system with necessary support equipment for replenishing the unit between sorties, and the overall system optimized including the impact of the support systems. This effect is exacerbated if PLSS components are used for life support in small pressurized rovers or space exploration vehicles, as with (for example) the requirement for METOX recharging spikes at the end of each extended mission, rather than the more steady demand if functionality is limited to local EVA support.
The Environmental Monitoring/Safety theme area has two high-priority technologies:
• 6.4.2. Fire Detection and Suppression
• 6.4.4. Remediation: Restores air quality following a fire or other contaminating event
Technology 6.4.2, Fire Detection and Suppression
Level 3 technology 6.4.2 Fire Detection and Suppression is concerned with ensuring crew health and safety by reducing the likelihood of a fire and, if one occurs, minimizing risk to crew, mission, and/or systems. Areas of research include fire prevention, fire detection, fire suppression, and a proposed free-flying fire test bed with reduced gravity, lower total pressure, and higher oxygen partial pressure environments capabilities. Fire suppression and in-space fire test bed concept are the two areas that drove the high scores for Fire: Detection and Suppression
Fire prevention technology maturation, primarily materials flammability testing, is required for reduced-gravity environments and cabin total and oxygen partial pressures expected in the next generation human space systems. Understanding material flammability and combustion products in spacecraft operational environments is critical to fire prevention. A new round of materials testing can be avoided if microgravity cabin environments continue to operate at sea level conditions. However, there is still a need to understand the impact of reduced gravity environments on flammability and combustion products.
Fire detection systems have proven remarkably reliable in the space shuttle and the ISS programs, experiencing only one failure to date. Again, new validation is required for reduced gravity and new atmospheric pressure and oxygen partial pressure environments. Fire and/or smoke on a station or vehicle is not a hypothetical event: the Apollo One crew was lost on the pad in 1967, and one serious event on the Russian space station, Mir, in 1997, nearly resulted in loss of both crew and vehicle.
Current fire prevention approaches and technologies are at TRL 9 for 1-g and microgravity environments in sea level equivalent atmospheres. However, destinations to reduced gravity environments in spaceships with lower total pressure and higher oxygen partial pressure relative to sea level conditions offer new challenges. A new fire suppression approach using fine mist water spray has been demonstrated on ground fires that offers significant advantages to human space systems relative to current water spray and CO2 solutions (NRC, 2011, pp. 276, 277, 327). Since fine water mist sprays have not been tested in space environments it must be considered to be at TRL
4. Testing in reduced gravity and pressure environments expected for human exploration missions beyond LEO is needed to mature this technology.
Ground applications have demonstrated the ability to extinguish fires using approximately one third the amount of water as traditional approaches. Applying fine mist water spray fire suppression techniques to human space systems will eliminate adding large CO2 quantities into the atmosphere and significantly reduce fire suppression system mass relative to current water or CO2 systems. This technology is critical to NASA, foreign national space agencies, and commercial space programs as a means to reduce deep-space mission mass and improve fire suppression capabilities. NASA is well positioned to mature this technology for space applications and make it available for any and all space system providers.
The ISS can play a major role in safely maturing fire detection and suppression studies in the space environment by employing existing expendable visiting cargo vehicles. Expendable cargo vehicles can be outfitted with detection and suppression systems plus recording and transmission capabilities. Once the visiting vehicle has left the ISS, the internal pressure and oxygen partial pressure can be adjusted and a fire ignited and observed for a short time then extinguished using the new fine mist water spray. This provides a safe method to test sensors and suppression methods in a relevant environment prior to incorporating them into new human space systems.
Benefits include reduced fire suppression system mass and eliminating the hazard of adding significant CO2 to the human space system atmosphere. The risk of maturing this technology is relatively low as it has already been demonstrated in ground tests and can be tested in space away from humans after an expendable cargo vehicle is on its deorbit trajectory. Ultra-high-pressure fire suppression is game-changing because it can reduce fire suppression water mass by 10 to 33 percent as well as time to extinguish and it will be impossible to “abandon ship” on long-duration deep space exploration missions. As an example, Mir was almost abandoned due to the difficulty in extinguishing an oxygen generation candle fire and it took days to recover from its effects. In addition, there were two space shuttle incidents with smoldering electrical fires that were not detected by fire sensors but were noticed by crew members.
The space station offers a chance for testing in a relevant environment for NEO missions and transit periods between Earth and the Moon or Mars. Testing at Moon and Mars gravity levels on reduced-gravity aircraft flights would also be valuable. This will help understand the impact gravity has on sensors that rely on airflow due to buoyancy. Results can also be used to validate computer simulations.
Technology 6.4.4, Remediation
The panel elevated this technology to high-priority status based on Mir, the ISS, and space shuttle experiences with fire and post-fire remediation. Mir was almost abandoned due to an oxygen generation candle fire and several days were required to recover from its effects. Alcohol in surface wipes used on the ISS to clean surfaces had a deleterious effect on the ECLSS components. On the space shuttle there were two smoldering electrical fires detected by crew members through their sense of smell that electronic sensors failed to detect.
The issues behind these failures need to be thoroughly understood and corrected before long-duration missions are conducted where vehicle abandonment is not an option, systems must operate throughout the mission, and situational awareness is critical to survival, not just mission success.
The ISS will be a critical component of technology development and certification.
MEDIUM- AND LOW-PRIORITY TECHNOLOGIES
TA06 includes eight level 3 technologies that ranked low or medium priority. Of course, many of these technologies will be integral to a final successful design of future operational systems. However, investments in some technologies will produce greater benefits that investments in others. In fact, the division of TA06 technologies was driven by the panel assessment of their expected benefit: all of the high-priority technologies were assigned a maximum score of 9 for benefit; all of the medium-priority technologies were assigned a benefit score of 3, and all of the low-priority technologies were assigned a benefit score of 1. Specific factors that contributed to this scoring are detailed below for some of the medium and low technologies.
Technology 6.2.3, EVA Power, Avionics, and Software, includes important areas of development, but they are likely to be paced by non-EVA, and primarily non-NASA, domain requirements.
Technology 6.3.3, Human Health and Performance Behavioral Health and Performance, was identified as a medium priority based on the knowledge that behavioral health issues will inevitably occur during exploration class missions based on prior experience, but the roadmap is unclear on the nature of the technologies envisioned for some elements of this technology.
Technology 6.3.1, Human Health and Performance, includes a strong emphasis in the roadmap on prediction of future health events by comprehensive screening, and newer processes such as DNA variant screening could indeed incrementally improve criteria for crew selection, but such predictions are unlikely to eliminate the need for planning for in-flight care of those same health conditions. Also, much of the knowledge to be gained in this area will accrue from large cohort studies and from harvesting of clinical data from electronic medical records systems, combined with high-throughput laboratory measurements of the human genome (DNA) and other biologically important classes of molecules, but this will require many more study participants than NASA can reasonably afford, so advances in this technology will also be driven by research conducted outside of NASA.
Technology 6.4.1, Sensors: Air, Water, Microbial, etc., received lower scores due to the relatively small mass, power, and volume impacts that advances in this technology would make on human space systems and adequacy of current systems. (A possible exception may be related to recent data on water-borne molds or mildews emerging on the ISS, similar to reported and observed growths on the Russian Mir space station.)
Technology 6.4.3, Protective Clothing/Emergency Breathing (including long-duration clothing, protective coveralls, oxygen masks, etc.), is a low priority because of the adequacy of current and alternative methods for achieving goals in this technology. For example, clothing mass can be minimized by incorporating a clothes washer and dryer rather than requiring longer-wear outfits, and improvements in emergency breathing capability can be made by increasing the number of portable and umbilical breathers throughout the habitable volume and increasing their operable life or providing more spares.
DEVELOPMENT AND SCHEDULE CHANGES FOR
TECHNOLOGIES COVERED BY THE TA06 ROADMAP
• Requirements linked to destinations,
• Microgravity testing on the International Space Station,
• Microgravity testing on the Moon, and
• Asteroid missions.
The discussion of those topics in Appendix J also pertains to the roadmap for TA06 Human Health, Life Support, and Habitation Systems.
OTHER GENERAL COMMENTS ON THE ROADMAP: HUMAN FACTORS
There was one evident gap within the TA06 roadmap, which involved Human Factors technologies. The panel encourages NASA to continue research in microgravity and reduced gravity human factors (and related technologies), and to maintain and update NASA Standard 3001 in order to ensure, among other things, that variable gravity environments are captured in spacecraft design, EVA suit design, and habitat design. Ideally, past human factors “lessons learned” since the beginning of the human spaceflight program would be added to the electronic database and shared with the commercial community (as recommended to the panel at the public session by the commercial spaceflight community). The panel had no evidence that the commercial community was generating any of this measurement technology or human factors information independently, and access to the current and future data (with appropriate export controls) was stated during the panel’s public sessions as critical to their success.
In addition, if future mission requirements place an emphasis on ensuring that exploration missions can involve as large a segment of the population as possible, laser scanning technology and relevant (military and civilian) human anthropometric databases could be used to define the required anthropometric measurements which will be utilized for human systems designs (spacecraft, EVA, rovers, surface habitats). This could include advanced technologies which would allow custom sized EVA suits to be cost effectively manufactured directly from laser scan electronic databases. Although, this is a matter of national policy, it seems prudent that spacecraft and EVA suits be developed and designed so that future crew anthropometric requirements are no less than those which were established for the space shuttle in the 1970s. The panel was presented with data which showed that original astronaut selection size standards have been narrowing since the late 1980s due to budget pressures, (e.g., reducing EVA suit sizes) and, more recently, to the acceptance of Russian Soyuz vehicle for crew transportation and the Russian Orlan EVA suit standards, which are sized primarily for a narrow range of Russian males. Current crew selection requirements for the ISS would now preclude many of the former space shuttle era astronauts from being considered (both men and women). This will also have a significant impact for the commercial community as they move into a LEO presence with humans.
PUBLIC WORKSHOP SUMMARY
The Human Systems Panel covered the Human Health, Life Support, and Habitation Systems technology area on April 26, 2011. The discussion was led by Panel Chair Bonnie J. Dunbar. Dunbar started the day by giving a general overview of the NRC’s task to evaluate the roadmaps along with some direction for what topics the invited speakers should cover in their presentations. After this introduction, several sessions were held addressing the key areas of each roadmap or representatives of key areas of interest. For each of these sessions, experts from industry, academia, and/or government were invited to provide a brief presentation/discussion of their comments on the NASA roadmap. At the end of each session, there was a short open discussion by the workshop attendees focusing on the recent session. At the end of the day, there was a concluding discussion by the panel chair summarizing the key points observed during the day’s discussion.
Session 1: NASA Human Exploration Framework Team (HEFT) Status
The first session of the day was aimed at providing an overview of NASA’s latest studies regarding the future direction of human spaceflight and exploration.
Christopher Culbert (NASA-JSC) started the session by providing background on the work HEFT had completed and key findings. One significant finding was that HEFT could not find an architecture that could close technically and financially within an appropriate timeframe that was politically sustainable. Other key findings suggested that no single architecture could achieve all objectives, satisfying all stakeholders is not feasible, and the politically proposed 15-year analysis horizon is too short. Culbert also provided a brief introduction to the Human Spaceflight Architecture Team (HAT) and indicated that both the HEFT and HAT identified technologies align well with the NASA roadmaps.
Scott Vangen (NASA-HQ) provided additional insight into the findings of the HEFT efforts. Based on the technologies evaluated by HEFT, he indicated that extended duration missions on the lunar surface and all missions beyond the Moon require substantially more technology investments than LEO, Cis-lunar, and short-duration lunar surface missions. Additionally, while a majority of necessary technologies can be matured in 3 to 8 years, some key technologies for Mars missions require longer lead time. He then cited radiation protection/shielding as an example of a long-lead technology investment.
Session 2: Roadmap Overview by NASA
The presentation by the NASA roadmap development team described the five level 2 subareas within TA06, including specific examples of the level 3 technologies within each subarea. The specific examples of each level 3 technology provided a description of the particular solution along with a discussion of critical test facilities,
technology readiness levels, and mission applicability. The briefing included a chronologically sorted list of 17 top technical challenges, though the briefing did not describe a direct one-to-one mapping between the challenges and the level 3 technologies. At the conclusion of the briefing, the panel questioned whether or not a comprehensive survey of available technical solutions had been completed. The roadmap team responded that the technology examples used in the roadmaps were based on what was known or readily available to the NASA team.
Session 3: Environmental Control and Life Support Systems (ECLSS) and Habitation Systems
Jordan Metcalf (NASA-JSC) started the session with an overview of ECLSS from an operational perspective. In reviewing the TA06 ECLSS Roadmap, he identified the key technology drivers to be high-reliability processes and integrated systems, increased self-sufficiency, and minimized logistics supply. Additionally, he identified regenerative ECLSS as game-changing for long-duration human spaceflight and suggested that further development of the ISS regenerative ECLSS shows the greatest promise for a point of departure for exploration beyond LEO.
Daniel Barta (NASA-JSC) provided an assessment of the current state of the art of ECLSS and habitation technologies conducted by the NASA Exploration Technology Development Program (ETDP). This assessment included TRLs for specific items within each level 3 technology, issues with current state-of-the-art systems, and new technology requirements for various destinations/applications. Although some technologies may have been used in flight, Barta noted that the TRL of these technologies has to be degraded if they are to be operated in a different environment, such as a planetary surface.
In the discussion session, the panel raised the issue of reduced-gravity considerations in technology development and whether or not ETDP was considering these issues in their assessment. Barta indicated that although reduced-gravity considerations were important for some technologies, g-neutral solutions were optimal. Additionally, there was some discussion on the use of technologies that can perform multiple functions and whether or not from a systems engineering perspective this was good or bad. It was generally agreed upon by both the speakers and the panel that maximizing commonality was highly desirable for human exploration spaceflight.
Session 4: Human Health and Performance
Jeffrey Davis (NASA-JSC), Director of Space Life Sciences, started the session with an overview of Space Life Sciences and their portfolio of work. His group had developed an evidence-based risk management system through which 65 human system risks had been identified. In reviewing the TA06 roadmap, he identified numerous key opportunities to synergize the technology developments of the OCT roadmaps with the investment portfolio of the NASA Human Research Program.
Jeffrey Sutton (National Space Biomedical Research Institute) provided a brief overview of his institute’s activities. Regarding the TA06 Human Health and Performance Roadmap, he cited imaging technology as a high priority across multiple organizations. Additionally, Sutton identified the top technical challenges to be individual susceptibility to radiation, access to the ISS, and barriers to international cooperation.
In the discussion session, the conversation centered on radiation protection and environment characterization, topics closely tied to human health. Sutton indicated that although the radiation environment outside LEO, specifically between Earth and Mars, is adequately well understood, important factors must be taken into account such as the exposure levels that are acceptable and the amount of shielding needed. Furthermore, there is a complex trade space between human health/safety and the added cost/mass of radiation shielding.
Session 5: Environmental Monitoring, Safety and Emergency Response
Nigel Packham (NASA-JSC) started the session with his assessment of this section of the TA06 roadmap. While the roadmap adequately addresses the challenges associated with environmental monitoring and control, fire prevention, detection, and suppression, Packham noted that it fails to suggest partnering with other government agencies that have similar challenges in terms of closed systems and long-duration sorties. Additionally,
he suggested that the TA06 roadmap identified target dates for technology demonstration on the ISS that require station operations until 2030, 10 years longer that what is currently planned. Lastly, when asked about challenges, Packham recognized the largest challenge with remediation was trading venting and cleanup versus compartmentalization and habitable volume.
Ralph Cacace (Honeywell Defense and Space) provided a brief overview of current state-of-the-art smoke detectors used on the ISS. He indicated a growing focus on miniaturization of sensors. Beyond size, other desired sensor characteristics included high accuracy, low power, and what was termed as smart sensors. These smart sensors combine multiple simple measurements with applied physics to produce more complex measurements.
Session 6: Extra Vehicular Activity (EVA)
Jim Buchli (Oceaneering) started the session with a programmatic perspective of the roadmap. He identified three key considerations for the EVA Roadmap: a clear definition of the mission and requirements, a critical mass of technical skills and experience, and the deployment of technologies that are flexible, producible, and supportable. Additionally, Buchli identified the top EVA technical challenges to be gloves, mobility, modularity of the portable life support system (PLSS), and miniaturization of electronics.
Brian Johnson (NASA-JSC) began with an overview of NASA’s recent EVA technology development efforts by ETDP. He also noted that the HEFT studies reaffirmed the development of space suits as one of the top “destination system” elements to be addressed. He then presented a set of strategic objectives for EVA technology advancement: increased safety and reliability, lower system mass, autonomous operations, expanded anthropometric limits, and lower cost. Lastly, Johnson provided a list of gaps in the current NASA EVA portfolio which included battery specific energy, radiation protection, alternative heat rejection, suit materials/dust, and advanced PLSS packaging and materials.
In the discussion session, the panel posed a question regarding the “academic pipeline” to sustain the development of EVA systems in the future. Buchli responded saying that the number of universities focusing on suit development has definitely been reducing. The panel then questioned the latest advancements in dust mitigation for space suits. Johnson referenced the studies and progress of the former Constellation Program indicating that significant work had been done in this area prior to being cancelled.
Session 7: Radiation
Martha Clowdsley (NASA-LaRC) started the session with a description of radiation protection as an integrated approach consisting of active shielding, forecasting, detection, bio/medical measures, and structure/materials/configuration optimization. She then went on to provide a series of recommendations. For radiation shielding, Clowdsley recommended continued basic materials research and a broad effort to raise the TRLs of existing shielding materials. For exposure analysis tools, she recommended multiple ways to improve both space radiation transport calculations and vehicle/habitat analyses to improve NASA’s radiation modeling capabilities for beyond LEO long-duration exploration.
Edward Semones (NASA-JSC) provided an overview of radiation monitoring technologies. Regarding the difference between LEO and exploration missions, he informed the panel that the radiation dosage rates were significantly higher (by a factor of 2 to 3) for exploration missions as well as being much longer, emphasizing that exploration missions would likely challenge the established human radiation risk limits set by NASA. Additionally, Semones identified the key challenges associated with radiation monitoring technologies to be improved battery technology for personal dosimeters, fail-safe data storage and transmission, in situ active warning and monitoring, and data for forecasting models (particularly for forecasting SPEs).
In the discussion session, the panel asked what international assets were available for space weather monitoring. Semones responded saying that there were none outside of those the United States had already collaborated on: ACE, GOES, SOHO, and STEREO space weather monitoring satellites. The panel also posed the question of which technology showed the most promise, biological countermeasures or radiation shielding. Clowdsley
responded by saying that the initial focus should be to reduce the biological uncertainty associated with the effects of the space radiation environment.
Session 8: Industry Panel
Paul Zamprelli (Orbital Technologies Corporation) started the session with a summary of the technology developments being conducted by ORBITEC. Pertaining to the technologies covered by TA06, Zamprelli discussed the company’s hybrid ECLSS resource recovery development. This system is being designed to demonstrate 90 percent oxygen and 98 percent water resource recovery closure compared to the 60 percent closure demonstrated by the ISS ECLSS. Currently, according to Zamprelli, the ORBITEC hybrid ECLSS has demonstrated approximately 84 percent closure at the time of the workshop.
Barry Finger (Paragon Space Development Corporation) provided an overview of the current state of the art of ECLSS on the ISS. He then identified the need for a simple, reliable, and maintainable ECLSS for long-duration human spaceflight beyond LEO. Finger then went on to identify the ISS as a necessary test bed for ECLSS technologies. Regarding the TA06 Roadmaps, he believes that ECLSS advancements are true game-changing technologies for deep space human missions.
Greg Gentry (Boeing) provided a series of lessons learned from developing and maintaining the ECLSS on both the space shuttle and the ISS. These lessons learned were extensive and ranged from general “philosophical” lessons learned to specific component-level lessons learned. His overall lesson learned was that when changes are made in operational systems, be ready to deal with “unintended consequences.”
Edward Hodgson (Hamilton Sundstrand) provided his assessment of the TA06 EVA roadmap. He identified several possible gaps in the roadmap such as “on-back” mass and volume reduction to support Mars surface missions. Additionally, Hodgson suggested that the roadmap assumes comparable EVA sortie durations to history; however, radiation environments could significantly change the EVA architecture due to lack of protection/shielding leading to insignificant EVA operations.
NRC (National Research Council). 2008. Managing Space Radiation Risk in the New Era of Space Exploration. The National Academies Press, Washington, D.C.
NRC. 2011. Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era. The National Academies Press, Washington, D.C.