Life Support Systems Research Papers (original) (raw)

2025, Advances in Space Research

Plant-derived nutrients were successfully recycled in a Controlled Ecological Life Support System (CELSS) using biological methods. The majority of the essential nutrients were recovered by microbiologically treating the plant biomass in an aerobic bioreactor. Liquid effluent containing the nutrients was then returned to the biomass production component via a recirculating hydroponic system. Potato (Solanum tuberosum L.) cv. Norland plants were grown on those nutrients in either a batch production mode (same age plants on a nutrient solution) or a staggered production mode (4 different ages of plants on a nutrient solution). The study continued over a period of 418 days, within NASA Breadboard Project's Biomass Production Chamber at the Kennedy Space Center. During this period, four consecutive batch cycles (104&y harvests) and 13 consecutive staggered cycles (26-day harvests) were completed using reclaimed minerals and compared to plants grown with standard nutrient solutions. All nutrient solutions were continually recirculated during the entire 418 day study. In general, tuber yields with reclaimed minerals were within 10% of control solutions. Contaminants, such as sodium and recalcitrant organics tended to increase over time in solutions containing reclaimed minerals, however tuber composition was comparable to tubers grown in the control solutions.

2025

NASA and other space agencies have an interest in using plants for human life support in space. The plants could provide food and O2 for the humans, while removing CO2 and helping purify wastewater. Studies to date have shown that a wide range of crops can be grown in controlled environment conditions envisioned for space. Light is a critical factor both for crop productivity and system power costs, and recent improvements in LEDs make them a preferred lighting option for space. Because space systems would be tightly closed, issues such as ethylene build-up and management must be considered. Ultimately, the costs and reliability of biological life support options must be compared with more conventional life support approaches. Findings to date suggest that about 20-25 m 2 of crops could supply the O2 for one human, while about 50 m 2 would be required for food (dietary calories).

2025, In Vitro Cellular & Developmental Biology - Plant

The effects of light spectral quality on the growth of in vitro nodal cuttings of potato (Solarium tuberosum L.) cultivars Norland, Superior, Kennebec, and Denali were examined. The different light spectra were provided by Vita-Lite fluorescent (VF) (a white light control), blue fluorescent (BF), red fluorescent (RF), low-pressure sodium (LPS), and a combination of low-pressure sodium plus cool-white fluorescent lamps (LPS/CWF). For all cuhivars, stem lengths after 4 wk were longest under LPS, followed by RF, LPS/CWF, VF, and BF (in descending order). Microscopic studies revealed that cells were shortest when cultured in BF or VF environments, and were longest in RF or LPS lamp environments. The highest number of axillary branches occurred on plantlets grown with LPS or LPS/CWF, whereas the lowest number occurred with BF. No leaf or stem edema (callus or gall-like growths) occurred with LPS or LPS/CWF lighting, and no edema occurred on cv. Norland plantlets, regardless of lighting. Results suggest that shoot morphologic development of in vitro grown potato plants can be controlled by controlling irradiant spectral quality.

2025, Crop Science

This study examined the effects of light, temperature and carbon dioxide on the growth of potato (Solanum tuberosutn L.) in a controlled environment in order to ascertain the best growing conditions for potato in life support systems in space. 'Norland' and 'Russet Burbank' were grown in 6-L pots of peat-vermiculite for 56 d in growth chambers at the University of Wisconsin Biotron. Environmental factor levels included continuous light (24-h photoperiod) at 250, 400, and 550 Mmol m ! s~' PPF; constant temperature at 16,

2025, The Journal of Heart and Lung Transplantation

Background: Extracorporeal life support (ECLS) has been used for post-cardiotomy rescue, but its use as a bridge to heart transplantation (OHT) in patients with postsurgical or end-stage ventricular failure remains controversial. Methods: Records were reviewed for patients receiving ECLS for ventricular failure from January 1991 to August 2001. Patients listed for OHT were analyzed separately. Listing for OHT requirements were improbable myocardial recovery, absence of contraindications (central nervous system damage, high pulmonary resistance, ongoing infection, etc.), and parental consent. Outcome variables included patient demographics, diagnosis, days from ECLS initiation to United Network for Organ Sharing (UNOS) listing (latency), list time, renal function, and survival to discharge. Of 145 patients with ventricular failure who received ECLS, 21 pediatric patients were UNOS listed. Of 124 non-listed patients, 57 (46%) survived to discharge. All but 3 survivors were separated from ECLS in Յ7 days. Twelve underwent OHT and 10 survived to discharge (list time, 6 days; median ECLS time, 14 days). Five had ECLS discontinued without undergoing OHT (1 later underwent OHT, 2 survived to discharge). Five experienced complications while receiving ECLS and died without undergoing OHT. Six of 9 patients who required dialysis for renal failure died. Of 11 infants listed, 4 were weaned from ECLS without undergoing OHT (2 survived to discharge), 5 had OHT (ECLS support, 4 days; 4 survived to discharge) and 2 died (ECLS support, 16 and 47 days). (1) Extracorporeal life support can be used as a bridge to OHT (even among the infant population) for at least 2 weeks with acceptable survival and hospital discharge rates, and (2) renal insufficiency with the concomitant requirement for dialysis decreases the likelihood of survival before and after OHT.

2025, Journal of the American Society for Horticultural Science

Baked ceramic aggregates (fritted clay, arcillite) have been used for plant research both on the ground and in microgravity. Optimal control of water and air within the root zone in any gravity environment depends on physical and hydraulic properties of the aggregate, which were evaluated for 0.25-1-mm and 1-2-mm particle size distributions. The maximum bulk densities obtained by any packing technique were 0.68 and 0.64 g·cm-3 for 0.25-1-mm and 1-2-mm particles, respectively. Wettable porosity obtained by infiltration with water was ≈65%, substantially lower than total porosity of ≈74%. Aggregate of both particle sizes exhibited a bimodal pore size distribution consisting of inter-aggregate macropores and intra-aggregate micropores, with the transition from macro- to microporosity beginning at volumetric water content of ≈36% to 39%. For inter-aggregate water contents that support optimal plant growth there is 45% change in water content that occurs over a relatively small matric su...

2025

The use of the activated carbon produced from rice hulls to control NOx emissions for the future deep space missions has been demonstrated. The optimal carbonization temperature range was found to be between 600 C and 750 C. The burnoff... more

2025, Artificial Organs

that made contributions to the Sixth Istanbul Symposium are presented in Tables and. The data including ECLS numbers, ECLS type, age of patients, etiologies, ECLS durations, weaning rates, and survival rates are presented.

2025, The Evolution of Ancient Greek Philosophy (Dr. Jamuel Yaw Asare)

This paper explores the evolution of Ancient Greek Philosophy, tracing its development from the Pre-Socratic era through the Classical period to the Hellenistic age. By examining key figures such as Thales, Socrates, Plato, Aristotle, and the Stoics, we uncover how philosophical thought transitioned from cosmological inquiries to ethical and metaphysical reflections, ultimately shaping Western intellectual traditions. The analysis highlights the interplay between reason, ethics, and political context, demonstrating how Greek philosophy adapted to societal changes while laying the foundation for modern philosophical discourse.

2025, Journal of Medical Ethics

2025

Due to the high number of systems in a space mission architecture and to their complex interactions, identifying risk and critical operational dependencies is not obvious. Traditional systems engineering methodology and risk assessment does not capture the impact of interactions between systems nor the cascading effects of disruptions. Based on these considerations, the Systems Operational Dependency Analysis methodology was developed for use by systems analysts and decision makers. This methodology utilizes a parametric model of interdependencies between systems to quantify the direct and indirect impact of system disruptions on other systems, as well as identify root causes. The results are effective at providing decision support for prioritizing technology investment based on risk reduction associated with potential system disruptions. Expanding on research presented at IAC 2018 and based on a collaboration with NASA Marshall Space Flight Center, this paper applies the Systems Op...

2025, Advances in Space Research

Design decisions to aid the development of future space-based biological life support systems (BLSS) can be made with simulation models. Here we develop the biochemical stoichiometry for 1) protein, carbohydrate, fat, fiber, and lignin production in the edible and inedible p m s of plants; 2) food consumption and production of organic solids in urine, feces, and wash water by the humans; and 3) operation of the waste processor. Flux values for all components are derived for a steady-state system with wheat as the sole food source. The large-scale dynamics of a materially-closed (BLSS) computer model is described in a companion paper /I/. An extension of this methodology can explore multi-food systems and more complex biochemical dynamics while maintaining whole-system closure as a focus. * All values in grdperson-day calculated using integer atomic masses and equations . ** H20 values include only that involved in stoichiometric transformations of mass type, which does not include transpiration, drinking water, water associated with wet (as opposed to dry) biomass, etc. See /1/ for these values.

2025, HortScience

A system was developed for subjecting plants to elevated air ion levels. This system consisted of a rectangular Plexiglas chamber lined with a Faraday cage. Air ions were generated by corona discharge from frayed stainless steel fibers placed at one end of the chamber. This source was capable of producing varying levels of either positive or negative air ions. During plant exposures, environmental conditions were controlled by operating the unit in a growth chamber.

2025, Advances in Space Research

A major challenge of designing a bioregenerative life support system for Mars is the reduction of the mass, volume, power, thermal and crew-time requirements. Structural mass of the greenhouse could be saved by operating the greenhouse at low atmospheric pressure. This paper investigates the feasibility of this concept. The method of equivalent system mass is used to compare greenhouses operated at high atmospheric pressure to greenhouses operated at low pressure for three different lighting methods: natural, artificial and hybrid lighting.

2025

This study is designed to support one of three major focus areas in the Naval Supply Systems Command (NAVSUP) Worldwide Husbanding Improvement Process initiative. Existing contracting methodologies were analyzed using the following methods: characteristics of existing contract vehicles within forecasting and simulation frameworks; strengths, weaknesses, opportunities, threats (SWOT) analysis, and stakeholder analysis. Conclusions are drawn and recommendations are outlined for optimum methods of contracting for husbanding services as requested by the Worldwide Husbanding Process Improvement Action Team. Historical husbanding contract data were reviewed, including constraints and desired performance criteria. Implementation of a flat-rate, low-variability, well-defined and constant set of requirements minimizes risk and price fluctuations. Conversely, adoption of a cost-reimbursable contract type is both undesirable and infeasible. A contracting methodology that represents a best-value trade-off within constraints should be flexible and risk-based while offering performance-based incentives.

2025

In space, explorers need in situ food production • Space Farming enables colonization of space • Sustainable: minimize logistics of resupply • Supplies: Light, CO 2 , O 2 , Nutrients, Water, Seeds, Plant chamber -Soil ? • Crew Psychological well-being: green Earth • Food Systems: palatable, nutritious and safe source of fresh food (limited shelf-life <3yr) LADA VEGGIE CO 2 H 2 O O 2 Radiation Radiative heat transfer Buoyancy-driven Convection -1 g CO 2 H 2 O O 2 Radiation Radiative heat transfer The absence of gravity induces physical effects that alter the microenvironment surrounding plants and their organs. These effects include: increased boundary layers surrounding plant organs and the absence of convective mixing of atmospheric gases. In addition, altered behavior of liquids and gases is responsible for phase separation and for dominance of capillary forces in the absence of gravitational forces (moisture redistribution)

2025

Root respiration IS a biological phenomenon that controls plant growth and physiological development during a plant's lifespan. This process is dependent on the availability of oxygen in the system where the plant is located. In hydroponic systems, where plants are submerged in a solution containing vital nutrients but no type of soil, the availability of oxygen arises from the dissolved oxygen concentration in the solution. This oxygen concentration is dependent on the , gas-liquid interface formed on the upper surface of the liquid, as given by Henry's Law, depending on pressure and temperature conditions. Respiration rates of the plants rise as biomass and root zone increase with age. The respiration rate of Apogee wheat plants (Triticum aestivum) was measured as a function of light intensity (catalytic for photosynthesis) and C02 concentration to determine their effect on respiration rates. To determine their effects on respiration rate and plant growth microbial communities were introduced into the system, by Innoculum. Surfactants were introduced, simulating graywater usage in space, as another factor to determine their effect on chemical oxygen demand of microbials and on respiration rates of the plants. It is expected to see small effects from changes in C02 concentration or light levels, and to see root respiration decrease in an exponential manner with plant age and microbial activity.

2025, International Journal of Artificial Organs

Data from animal experiments with mechanical circulatory support systems (MCSS) performed in Groningen and Marseille over the past years were used to obtain normal values of hematological, coagulation, rheological and blood chemistry parameters in calves. These parameters were divided between two groups: a limited number of parameters necessary to assess biocompetibility properties of MeSS quickly and a more extensive number of parameters suitable for more detailed biological evaluation of blood pumps. All applied tests can be examined in calf blood as well as in human blood. Parameters were selected on clinical relevance and usefulness for standardization procedures. The obtained data were compared with normal values in human beings derived from the literature.

2025

One possible next leap in human space exploration for the National Aeronautics and Space Administration (NASA) is a mission to a near Earth asteroid (NEA). In order to achieve such an ambitious goal, a space habitat will need to accommodate a crew of four for the 380-day round trip. The Human Spaceflight Architecture Team (HAT) developed a conceptual design for such a habitat. The team identified activities that would be performed inside a long-duration, deep space habitat, and the capabilities needed to support such a mission. A list of seven functional activities/capabilities was developed: individual and group crew care, spacecraft and mission operations, subsystem equipment, logistics and resupply, and contingency operations. The volume for each activity was determined using NASA STD-3001 and the companion Human Integration Design Handbook (HIDH). Although, the sum of these volumes produced an over-sized spacecraft, the team evaluated activity frequency and duration to identify ...

2025, Resuscitation

The need for rescue breathing during the initial management of sudden cardiac arrest is currently being debated and reevaluated. The present study was designed to compare cerebral oxygen delivery during basic life support (BLS) by chest compressions only with chest compressions plus ventilation in pigs with an obstructed airway mimicked by a valve hindering passive inhalation. Resuscitability was then studied during the subsequent advanced life support (ALS) period. After 3 min of untreated ventricular fibrillation (VF) BLS was started. The animals were randomised into two groups. One group received chest compressions only. The other group received ventilations and chest compressions with a ratio of 2:30. A gas mixture of 17% oxygen and 4% carbon dioxide was used for ventilation during BLS. After 10 min of BLS, ALS was provided. All six pigs ventilated during BLS attained a return of spontaneous circulation (ROSC) within the first 2 min of advanced cardiopulmonary resuscitation (CPR) compared with only one of six compressions-only pigs. While all except one compressions-only animal achieved ROSC before the experiment was terminated, the median time to ROSC was shorter in the ventilated group. With a ventilation:compression ratio of 2:30 the arterial oxygen content stayed at 2/3 of normal, but with compressions-only, the arterial blood was virtually desaturated with no arterio-venous oxygen difference within 1.5-2 min. Haemodynamic data did not differ between the groups. In this model of very ideal BLS, ventilation improved arterial oxygenation and the median time to ROSC was shorter. We believe that in cardiac arrest with an obstructed airway, pulmonary ventilation should still be strongly recommended.

2025, 2009 International Symposium on Aviation Psychology

Combat aircraft advances have led to a dramatic increase in the operational tempo facing the Navy pilot, increasing the likelihood for Situation Awareness (SA) failures, biased decision-making and information overload. We designed a system for constructing intelligent adaptive displays to address these issues and, within it, designed and evaluated two interfaces targeted at tactical SA challenges: (1) a Weapons Employment Zone (WEZ) Display designed to support awareness of combat geometry; and (2) an Adaptive Boundary Display (ABD) designed to warn pilots of impending border infractions that would compromise Rules of Engagement (ROEs). We tested the ability of these displays to improve SA, reduce workload, and improve mission performance in a population of licensed civilian pilots. The WEZ Display significantly improved performance and SA and reduced workload, while the ABD made no significant improvements. We recommend using the WEZ Display to assist novice pilots in understanding and tracking real-time combat geometry.

2025

The future of Environmental Control and Life Support Systems (ECLSS) will rely on integrating these cutting-edge technologies to create safer, more efficient systems. Learn more in ECLSS courses by Tonex.

2025

A miniature electronic nose in which the sensing media are insulating polymers loaded with carbon _black as a conductive medium has been designed and built at the Jet Propulsion Laboratory. The ENose has a volume of 1700 em 3, weighs 1.4 kg including the operating computer, and uses 1.5 W average power (3 W peak power). This ENose was used in a demonstration experiment aboard STS-95 (October, 1998), in which the ENose was operated continuously for six days and recorded the sensors' response to the air in the middeck. The ENose was designed to detect ten common contaminants in space shuttle crew quarters air. The experiment was controlled by collecting air samples daily and analyzing them using standard analytical techniques after the flight. Changes in humidity were detected and quantified; neither the ENose nor the air samples detected any of the contaminants on the target list. The device is microgravity insensitive.

2024, Advances in Space Research

2024

Cet article presente une analyse des contraintes mecaniques agissant sur des pylones haubanes d'aerogenerateurs de puissance et les technologies mises en œuvre pour leur installation. Le pylone supportant la nacelle, le rotor et le câble electrique constitue l'element important qui conditionne dans une tres large mesure la stabilite de l'installation dans son ensemble. Les haubans, destines a assurer l'equilibre du pylone, doivent etre judicieusement ancres au sol; le choix du type de ces ancrages depend essentiellement de la nature du sol, de sa capacite portante et des efforts qui agissent sur l'installation. L'etape importante relative a l'installation de l'aerogenerateur doit prendre en consideration les moindres details comme l'emprise au sol, les contraintes mecaniques et les precautions electriques (mise a la terre, foudre, etc.) afin de bien s'assurer de sa fiabilite et de le garder en bon etat de fonctionnement tout au long de sa vie ...

2024, Unknown

In the future, two important technological dreams will have become reality: fusion will be a viable power source, and human settlement on Mars will be feasible, desirable, and even necessary. Merging these two concepts is especially... more

2024, Acta Astronautica

Using remote sensing technique, we investigated real-time Nostoc sphaeroides K utz (Cyanobacterium) in Closed System under microgravity by SHENZHOU-2 spacecraft in January 2001. The experiments had 1g centrifuges in space for control and ground control group experiments were also carried out in the same equipments and under the same controlled condition. The data about the population growth of Nostoc sp. of experiments and temperature changes of system were got from spacecraft every minute. From the data, we can ÿnd that population growth of Nostoc sp. in microgravity group was higher than that of other groups in space or on ground, even though both the control 1g group in space and 1g group on ground indicated same increasing characteristics in experiments. The growth rate of 1:4g group (centrifuged group on ground) was also promoted during experiment. The temperature changes of systems are also a ected by gravity and light. Some aspects about those di erences were discussed. From the discussion of these results during experiment, it can be found that gravity is the major factor to lead to these changes.

2024, Aviation, space, and environmental medicine

The maintenance of crew performance during extended space missions has been a major concern because of the problems associated with prolonged isolation and confinement. Previous research has failed to address this problem by not using appropriate performance tests. Three Russian cosmonauts were tested on a PC-based simulation of a spacecraft's life support system during a 135-d simulation of a MIR spaceflight. A complex multiple-task environment was used to examine a comprehensive range of task management variables, including both primary and secondary task performance, control activity and information sampling behavior. Subjective state variables were also measured. The data suggested an overall successful adjustment to isolation and confinement, though some indications of temporary disruptions of some performance indicators were observed. Information sources were sampled less frequently with increasing mission length while system control activities showed a tendency to increas...

2024, Journal of the American Society for Horticultural Science

Photoperiod and harvest scenario of cowpea (Vigna unguiculata L. Walp) canopies were manipulated to optimize productivity for use in future controlled ecological life-support systems. Productivity was measured by edible yield rate (EYR : g•m -2 •day -1 ), shoot harvest index (SHI : g edible biomass•[g total shoot dry weight]), and yield-efficiency rate (YER : g edible biomass•m -2 •day -1 per [g nonedible shoot dry weight]). Breeding lines 'IT84S-2246' (S-2246) and 'IT82D-889' (D-889) were grown in a greenhouse under 8-, 12-, or 24-h photoperiods. S-2246 was short-day and D-889 was day-neutral for flowering. Under each photoperiod, cowpeas were harvested either for leaves only, seeds only, or leaves plus seeds (mixed harvest). Photoperiod did not affect EYR of either breeding line for any harvest scenario tested. Averaged over both breeding lines, seed harvest gave the highest EYR at 6.7 g•m -2 •day -1 . The highest SHI (65%) and YER (94 mg•m -2 •day -1 •g -1 ) were achieved for leaf-only harvest of D-889 under an 8-h photoperiod. For leaf-only harvest of S-2246, both SHI and YER increased with increasing photoperiod, but declined for seed-only and mixed harvests. However, photoperiod had no effect on SHI or YER for D-889 for any harvest scenario. A second experiment utilized the short-day cowpea breeding line 'IT89KD-288' (D-288) and the day-neutral breeding line 'IT87D-941-1' (D-941) to compare yield parameters using photoperiod extension under differing lamp types. This experiment confirmed the photoperiod responses of D-889 and S-2246 to a mixed-harvest scenario and indicated that daylength extension with higher irradiance from high pressure sodium lamps further suppressed EYR, SHI, and YER of the short-day breeding line D-288.

2024, Hortscience

The day-neutral, semidwarf rice (Oryza sativa L.) cultivar Ai-Nan-Tsao was grown in a greenhouse under summer conditions using high-pressure sodium lamps to extend the natural photoperiod. After allowing 2 weeks for germination, stand establishment, and thinning to a consistent planting density of 212 plants/m 2 , stands were maintained under continuous lighting for 35 or 49 days before shifting to 8-or 12-h photoperiods until harvest 76 days after planting. Non-shifted control treatments consisting of 8-, 12-, or 24h photoperiods also were maintained throughout production. Tiller number increased as duration of exposure to continuous light increased before shifting to shorter photoperiods. However, shoot harvest index and yield efficiency rate were lower for all plants receiving continuous light than for those under the 8-or 12-h photoperiods. Stands receiving 12-h photoperiods throughout production had the highest grain yield per plant and equaled the 8-h-photoperiod control plants for the lowest tiller number per plant. As long as stands were exposed to continuous light, tiller formation continued. Shifting to shorter photoperiods late in the cropping cycle resulted in newly formed tillers that were either sterile or unable to mature grain before harvest. Late-forming tillers also suppressed yield of grain in earlyforming tillers, presumably by competing for photosynthate or for remobilized assimilate during senescence. Stands receiving 12-h photoperiods throughout production not only produced the highest grain yield at harvest but had the highest shoot harvest index, which is important for resource-recovery strategies in advanced life-support systems proposed for space.

2024

How should life support for deep space be developed? The International Space Station (ISS) life support system is the operational result of many decades of research and development. Long duration deep space missions such as Mars have been expected to use matured and upgraded versions of ISS life support. Deep space life support must use the knowledge base incorporated in ISS but it must also meet much more difficult requirements. The primary new requirement is that life support in deep space must be considerably more reliable than on ISS or anywhere in the Earth-Moon system, where emergency resupply and a quick return are possible. Due to the great distance from Earth and the long duration of deep space missions, if life support systems fail, the traditional approaches for emergency supply of oxygen and water, emergency supply of parts, and crew return to Earth or escape to a safe haven are likely infeasible. The Orbital Replacement Unit (ORU) maintenance approach used by ISS is unsuitable for deep space with ORU's as large and complex as those originally provided in ISS designs because it minimizes opportunities for commonality of spares, requires replacement of many functional parts with each failure, and results in substantial launch mass and volume penalties. It has become impractical even for ISS after the shuttle era, resulting in the need for ad hoc repair activity at lower assembly levels with consequent crew time penalties and extended repair timelines. Less complex, more robust technical approaches may be needed to meet the difficult deep space requirements for reliability, maintainability, and reparability. Developing an entirely new life support system would neglect what has been achieved. The suggested approach is use the ISS life support technologies as a platform to build on and to continue to improve ISS subsystems while also developing new subsystems where needed to meet deep space requirements.

2024, International Conference on Environmental Systems

2024

The development of commercial launch vehicles by SpaceX has greatly reduced the cost of launching mass to Low Earth Orbit (LEO). Reusable launch vehicles may further reduce the launch cost per kilogram. The new low launch cost makes open loop life support much cheaper than before. Open loop systems resupply water and oxygen in tanks for crew use and provide disposable lithium hydroxide (LiOH) in canisters to remove carbon dioxide. Short human space missions such as Apollo and shuttle have used open loop life support, but the long duration International Space Station (ISS) recycles water and oxygen and removes carbon dioxide with a regenerative molecular sieve. These ISS regenerative and recycling life support systems have significantly reduced the total launch mass needed for life support. But, since the development cost of recycling systems is much higher than the cost of tanks and canisters, the relative cost savings have been much less than the launch mass savings. The Life Cycle Cost (LCC) includes development, launch, and operations. If another space station was built in LEO, resupply life support would be much cheaper than the current recycling systems. The mission most favorable to recycling would be a long term lunar base, since the resupply mass would be large, the proximity to Earth would reduce the need for recycling reliability and spares, and the launch cost would be much higher than for LEO due to the need for lunar transit and descent propulsion systems. For a ten-year lunar base, the new low launch costs make resupply cheaper than recycling systems similar to ISS life support.

2024

A hardware system's failure rate often increases over time due to wear and aging, but not always. Some systems instead show reliability growth, a decreasing failure rate with time, due to effective failure analysis and remedial hardware upgrades. Reliability grows when failure causes are removed by improved design. A mathematical reliability growth model allows the reliability growth rate to be computed from the failure data. The space shuttle was extensively maintained, refurbished, and upgraded after each flight and it experienced significant reliability growth during its operational life. In contrast, the International Space Station (ISS) is much more difficult to maintain and upgrade and its failure rate has been constant over time. The ISS Carbon Dioxide Removal Assembly (CDRA) reliability has slightly decreased. Failures on ISS and with the ISS CDRA continue to be a challenge. Nomenclature CDRA = Carbon Dioxide Removal Assembly ECLS = Environmental Control and Life Support ISS = International Space Station MTBF = Mean Time Before Failure NHPP = Non-Homogeneous Poisson Process WHC = Waste and Hygiene Compartment

2024, International Conference on Environmental Systems (ICES)

A proposed Photocatalytic Air Processor (PAP) would combine two atmosphere revitalization functions for a crewed spacecraft, carbon dioxide removal and oxygen provision. The axiomatic design method is used to develop the general requirements and alternate system designs that combine these two atmosphere revitalization functions. There are two current atmosphere revitalization approaches. Short missions such as the space shuttle use lithium hydroxide (LiOH) to remove carbon dioxide and tanks to provide oxygen. The ISS (International Space Station) uses the CDRA (Carbon Dioxide Removal Assembly) to remove carbon dioxide and a Sabatier reactor and OGA (Oxygen Generation Assembly) to provide oxygen. The PAP could replace either of these combined systems, LiOH and oxygen tanks or the CDRA, Sabatier, and OGA. Axiomatic design is used to investigate these alternate high level system designs for atmosphere revitalization. The axiomatic design approach develops the requirements and design together from higher to lower system level, using a back-and-forth and top-down process. One objective is to reduce the coupling between design elements, which is a measure of system complexity. The equivalent system mass of the alternate systems is compared.

2024

NASA's spectacular success in the Apollo moon landings was achieved against the odds by an obsessive dedication to reducing the great risk. However, risk analysis predicted so many astronaut fatalities that it was thought to be unreasonably pessimistic and potentially damaging to the Apollo program. Risk analysis was discontinued, risk was neglected in space shuttle engineering, and so the space shuttle design was unnecessarily dangerous. Since the Apollo era it has been understood that long human space missions would recycle oxygen and water to avoid the very high launch cost of directly supplying them. The development of recycling systems was justified by the need to increase material closure and reduce launch mass. When it was recognized that increasing closure leads to rapidly diminishing returns, the program goal was changed to reducing launch mass and reliability, cost, and risk were considered irrelevant. Systems engineering and especially the discouraging problems of risk and cost have been deliberately ignored because they detract from program promotion, with unfortunate results. Current human launch system design does account for risk and the result strongly resembles Apollo. Current life support design continues to assume recycling, even though the recent great reduction in launch cost now allows direct supply of oxygen and water with significantly better quality, reliability, cost, and risk.

2024, International Conference on Environmental Systems (ICES)

Cost-effective high reliability can be achieved in future space life support systems through careful systems analysis and design. This paper outlines a comprehensive approach. Potential future human space missions are described. The mission parameter impacts on life support system design and reliability requirements are discussed. Not all human space missions require high reliability life support. The potential reliability and cost of storage and of recycling life support systems are investigated. Simple storage systems can provide costeffective high reliability life support where it is needed. More complex recycling systems with lower reliability and higher cost can be used when suitable.

2024, International Conference on Environmental Systems

System reliability can be significantly improved by a strong continued effort to identify and remove all the causes of actual failures. Newly designed systems often have unexpected high failure rates which can be reduced by successive design improvements until the final operational system has an acceptable failure rate. There are many causes of failures and many ways to remove them. New systems may have poor specifications, design errors, or mistaken operations concepts. Correcting unexpected problems as they occur can produce large early gains in reliability. Improved technology in materials, components, and design approaches can increase reliability. The reliability growth is achieved by repeatedly operating the system until it fails, identifying the failure cause, and fixing the problem. The failure rate reduction that can be obtained depends on the number and the failure rates of the correctable failures. Under the strong assumption that the failure causes can be removed, the decline in overall failure rate can be predicted. If a failure occurs at the rate of λ per unit time, the expected time before the failure occurs and can be corrected is 1/λ, the Mean Time Before Failure (MTBF). Finding and fixing a less frequent failure with the rate of λ /2 per unit time requires twice as long, time of 1/(2 λ). Cutting the failure rate in half requires doubling the test and redesign time and finding and eliminating the failure causes. Reducing the failure rate significantly requires a heroic reliability improvement effort. Nomenclature CCF = Common Cause Failures CDRA = Carbon Dioxide Removal Assembly ECLS = Environmental Control and Life Support ISS = International Space Station MTBF = Mean Time Before Failure OGA = Oxygen Generation Assembly

2024, 42nd International Conference on Environmental Systems

This report describes a flexible, reliable, deep space life support system design approach that uses either storage or recycling or both together. The design goal is to provide the needed life support performance with the required ultra reliability for the minimum Equivalent System Mass (ESM). Recycling life support systems used with multiple redundancy can have sufficient reliability for deep space missions but they usually do not save mass compared to mixed storage and recycling systems. The best deep space life support system design uses water recycling with sufficient water storage to prevent loss of crew if recycling fails. Since the amount of water needed for crew survival is a small part of the total water requirement, the required amount of stored water is significantly less than the total to be consumed. Water recycling with water, oxygen, and carbon dioxide removal material storage can achieve the high reliability of full storage systems with only half the mass of full storage and with less mass than the highly redundant recycling systems needed to achieve acceptable reliability. Improved recycling systems with lower mass and higher reliability could perform better than systems using storage.

2024, International Conference on Environmental Systems