Element exchange in a water- and gas-closed biological Life Support System.

Liquid human wastes and household water used for nutrition of wheat made possible to realize 24% closure for the mineral exchange in an experiment with a 2-component version of "Bios-3" life support system (LSS) Input-output balances of revealed, that elements (primarily trace elements) within the system. The structural materials (steel, titanium), expanded clay aggregate, and catalytic furnace catalysts. By the end of experiment, the permanent nutrient solution, plants, and the human diet gradually built up Ni, Cr, Al, Fe, V, Zn, Cu, and Mo. Thorough selection and pretreatment of materials can substantially reduce this accumulation. To enhance closure of the mineral exchange involves processing of human-metabolic wastes and inedible biomes inside LSS. An efficient method to oxidize wastes by hydrogen peroxide icon a quartz reactor at the temperature of 80 degrees C controlled electromagnetic field is proposed.     

Influence of high concentrations of mineral salts on production process and NaCl accumulation by Salicornia europaea plants as a constituent of the LSS phototroph link.

Use of halophytes (salt-tolerant vegetation), in a particular vegetable Salicornia europaea plants which are capable of utilizing NaCl in rather high concentrations, is one of possible means of NaCl incorporation into mass exchange of bioregenerative life support systems. In preliminary experiments it was shown that S. europaea plants, basically, could grow on urine pretreated with physicochemical processing and urease-enzyme decomposing of urea with the subsequent ammonia distillation. But at the same time inhibition of the growth process of the plants was observed. The purpose of the given work was to find out the influence of excessive quantities of some mineral elements contained in products of physicochemical processing of urine on the production process and NaCl accumulation by S. europaea plants. As the content of mineral salts in the human liquid wastes (urine) changed within certain limits, two variants of experimental solutions were examined. In the first variant, the concentration of mineral salts was equivalent to the minimum salt content in the urine and was: K - 1.5 g/l, P - 0.5 g/l, S - 0.5 g/l, Mg - 0.07 g/l, Ca - 0.2 g/l. In the second experimental variant, the content of mineral salts corresponded to the maximum salt content in urine and was the following: K - 3.0 g/l, P - 0.7 g/l, S - 1.2 g/l, Mg - 0.2 g/l, Ca - 0.97 g/l. As the control, the Tokarev nutrient solution containing nitrogen in the form of a urea, and the Knop nutrient solution with nitrogen in the nitrate form were used. N quantity in all four variants made up 177 mg/l. Air temperature was 24 degrees C, illumination was continuous. Light intensity was 690 micromoles/m2s of photosynthetically active radiation. NaCl concentration in solutions was 1%. Our researches showed that the dry aboveground biomass of an average plant of the first variant practically did not differ from the control and totaled 11 g. In the second variant, S. europaea productivity decreased and the dry aboveground biomass of an average plant totaled 8 g. The increase of K quantity in the experimental solutions resulted in an elevated content of the element in the plants. The increase of K uptake in the second experimental variant was accompanied by a 30-50% decrease of Na content in comparison with the other variants. Comparative Na content in the other variants was practically identical. N, Mg and P content in the control and experimental variants was also practically identical. The increase of S quantity in the second experimental variant also increased S uptake by the plants. But Ca quantity, accumulated in aboveground plants biomass in the experimental variants was lower than in the control. NaCl uptake by plants, depending on the concentration of mineral salts in the experimental solutions, ranged from 8 g (maximum salt content) up to 15 g (minimum salt content) on a plant growth area that totaled 0.032 m2. Thus, high concentrations of mineral salts simulating the content of mineral salts contained in urine did not result in a significant decrease of S. europaea productivity. The present work also considers the influence of higher light intensity concentrations on productivity and NaCl accumulation by S. europaea plants grown on experimental solutions with high salt content.     

A biological method of including mineralized human liquid and solid wastes into the mass exchange of bio-technical life support systems

The main obstacle to using mineralized human solid and liquid wastes as a source of mineral elements for plants cultivated in bio-technical life support systems (BLSS) is that they contain NaCl. The purpose of this study is to determine whether mineralized human wastes can be used to prepare the nutrient solution for long-duration conveyor cultivation of uneven-aged wheat and Salicornia europaea L. plant community. Human solid and liquid wastes were mineralized by the method of “wet incineration” developed by Yu. Kudenko. They served as a basis for preparing the solutions that were used for conveyor-type cultivation of wheat community represented by 5 age groups, planted with a time interval of 14 days. Wheat was cultivated hydroponically on expanded clay particles. To reduce salt content of the nutrient solution, every two weeks, after wheat was harvested, 12 L of solution was removed from the wheat irrigation tank and used for Salicornia europaea cultivation in water culture in a conveyor mode. The Salicornia community was represented by 2 age groups, planted with a time interval of 14 days. As some portion of the nutrient solution used for wheat cultivation was regularly removed, sodium concentration in the wheat irrigation solution did not exceed 400 mg/L, and mineral elements contained in the removed portion were used for Salicornia cultivation. The experiment lasted 4 months. The total wheat biomass productivity averaged 30.1 g · m⁻² · day⁻¹, and the harvest index amounted to 36.8%. The average productivity of Salicornia edible biomass on a dry weight basis was 39.3 g · m⁻² · day⁻¹, and its aboveground mass contained at least 20% of NaCl. Thus, the proposed technology of cultivation of wheat and halophyte plant community enables using mineralized human wastes as a basis for preparing nutrient solutions and including NaCl in the mass exchange of the BLSS; moreover, humans are supplied with additional amounts of leafy vegetables.     

Can incineration technology convert CELSS wastes to resources for crop production? A working hypothesis and some preliminary findings.

Considerable evidence exists to support the hypothesis that human-generated wastes can be utilized as resources in crop production. In the waste mix from a Closed Ecological Life Support System (CELSS), the elemental resources are found mainly in the solid fraction. In order to make these resources available for crop growth, it is necessary to convert the solid wastes to either an aqueous or a gaseous phase. Incineration is one method for processing solid wastes to produce a gaseous fraction and a small solid fraction of ash. Evidence from literature provides a compelling case for a working hypothesis that plants can utilize the gases of incineration. Although uptake and utilization of inorganic elements in the aqueous phase is well established, the uptake and utilization of inorganic elements in the gaseous phase, with the exception of CO2 and O2, is not fully understood. This paper attempts to (a) summarize existing literature on uptake/metabolism of inorganic elements in the gaseous fraction, with the exception of CO2 and O2 and (b) develop a working hypothesis to predict the use of incineration flue gases by plants. Preliminary experimental findings on effects of carbon monoxide, a component of the flue gas, are also presented.     

Mass exchange in an experimental new-generation life support system model based on biological regeneration of environment.

An experimental model of a biological life support system was used to evaluate qualitative and quantitative parameters of the internal mass exchange. The photosynthesizing unit included the higher plant component (wheat and radish), and the heterotrophic unit consisted of a soil-like substrate, California worms, mushrooms and microbial microflora. The gas mass exchange involved evolution of oxygen by the photosynthesizing component and its uptake by the heterotroph component along with the formation and maintaining of the SLS structure, growth of mushrooms and California worms, human respiration, and some other processes. Human presence in the system in the form of "virtual human" that at regular intervals took part in the respirative gas exchange during the experiment. Experimental data demonstrated good oxygen/carbon dioxide balance, and the closure of the cycles of these gases was almost complete. The water cycle was nearly 100% closed. The main components in the water mass exchange were transpiration water and the watering solution with mineral elements. Human consumption of the edible plant biomass (grains and roots) was simulated by processing these products by a unique physicochemical method of oxidizing them to inorganic mineral compounds, which were then returned into the system and fully assimilated by the plants. The oxidation was achieved by "wet combustion" of organic biomass, using hydrogen peroxide following a special procedure, which does not require high temperature and pressure. Hydrogen peroxide is produced from the water inside the system. The closure of the cycle was estimated for individual elements and compounds. Stoichiometric proportions are given for the main components included in the experimental model of the system. Approaches to the mathematical modeling of the cycling processes are discussed, using the data of the experimental model. Nitrogen, as a representative of biogenic elements, shows an almost 100% closure of the cycle inside the system. The proposed experimental model of a biological system is discussed as a candidate for potential application in the investigations aimed at creating ecosystems with largely closed cycles of the internal mass exchange. The formation and maintenance of sustainable cycling of vitally important chemical elements and compounds in biological life support systems (BLSS) is an extremely pressing problem. To attain the stable functioning of biological life support systems (BLSS) and to maintain a high degree of closure of material cycles in than, it is essential to understand the character of mass exchange processes and stoichiometnc proportions of the initial and synthesized components of the system.     

Biological and physiochemical methods for utilization of plant wastes and human exometabolites for increasing internal cycling and closure of life support systems.

Wheat was cultivated on soil-like substrate (SLS) produced by the action of worms and microflora from the inedible biomass of wheat. After the growth of the wheat crop, the inedible biomass was restored in SLS and exposed to decomposition ("biological" combustion) and its mineral compounds were assimilated by plants. Grain was returned to the SLS in the amount equivalent to human solid waste produced by consumption of the grain. Human wastes (urine and feces) after physicochemical processing turned into mineralized form (mineralized urine and mineralized feces) and entered the plants' nutrient solution amounts equal to average daily production. Periodically (once every 60-70 days) the nutrient solution was partly (up to 50%) desalinated by electrodialysis. Due to this NaCl concentration in the nutrient solution was sustained at a fixed level of about 0.26%. The salt concentrate obtained could be used in the human nutrition through NaCl extraction and the residuary elements were returned through the mineralized human liquid wastes into matter turnover. The control wheat cultivation was carried out on peat with use of the Knop nutrient solution. Serial cultivation of several wheat vegetations within 280 days was conducted during the experiment. Grain output varied and yield/harvest depended, in large part, upon the amount of inedible biomass returned to SLS and the speed of its decomposition. After achieving a stationary regime, (when the quantity of wheat inedible biomass utilized during vegetation in SLS is equal to the quantity of biomass introduced into SLS before vegetation) grain harvest in comparison with the control was at most 30% less, and in some cases was comparable to the control harvest values. The investigations carried out on the wheat example demonstrated in principle the possibility of long-term functioning of the LSS photosynthesizing link based on optimizations of biological and physicochemical methods of utilization of the human and plants wastes. The possibilities for the use of these technologies for the creation integrated biological-physicochemical LSS with high closure degree of internal matter turnover are discussed in this paper.     

Long-term experiments on man's stay in biological life-support system.

We describe the experimental system having maximal possible closure of material recycling in an ecosystem, including people and plants, which was carried out in a hermetically sealed experimental complex "BIOS-3", 315 m2 in volume. The system included 2 experimentators and 3 phytotrons with plants (total sowing area of 63 m2). Plants were grown with round-the-clock lamp irradiation with 130 Wm-2 PAR intensity. The plants production was food for people. Water exchange of ecosystem, as wall as gas exchange, was fully closed excluding liquids and gas samples taken for chemical analysis outside the system. The total closure of material turnover constituted 91%. Health state of the crew was estimated before, during and after the experiment. A 5-months period did not affect their health. The experiments carried out prove that the closed ecosystem of "man-plants" is a prototype of a life-support system for long-term space expeditions.     

Assessing the feasibility of involving gaseous products resulting from physicochemical oxidation of human liquid and solid wastes in the cycling of a bio-technical life support system

The study addresses the possible ways of involving gaseous products produced by “wet” incineration of human wastes mixed with H₂O₂ in an alternating electric field in the cycling of the physical model of a bio-technical life support system (BTLSS). The resulting gas mixture contains CO₂ and O₂, which are easily involved in the cycling in the closed ecosystem, and NH₃, which is unacceptable in the atmosphere of the BTLSS. NH₃ fixation has been proposed, which is followed by nitrification and involvement of the resulting products in the mass exchange of the closed system. Experiments have been performed to show that plants can be grown in the atmosphere resulting from the closing of the gas loop that includes a physicochemical installation and a growth chamber with plants representing the phototrophic compartment of the BTLSS. The results of the study suggest the conclusion that the proposed method of organic waste oxidation can be a useful tool in creating a physical model of a closed-loop integrated BTLSS.     

Integration test project of CEEF--a test bed for Closed Ecological Life Support Systems.

CEEF (Closed Ecology Experiment Facilities) were installed at Rokkasho village in northern Japan, for the purpose of clarifying life-support mechanisms in a completely closed space, such as a Lunar or Mars base. An integration test using the Closed Plantation Experiment Facility and Closed Animal Breeding & Habitation Experiment Facility is needed before conducting an entire closed experiment including plants, animals and humans. These integration tests are planned to be conducted step by step from fiscal 2001 to 2008.     

Effects of mineral nutrition conditions on heat tolerance of chufa (Сyperus esculentus L.) plant communities to super optimal air temperatures in the BTLSS

The use of mineralized human wastes as a basis for nutrient solutions will increase the degree of material closure of bio-technical human life support systems. As stress tolerance of plants is determined, among other factors, by the conditions under which they have been grown before exposure to a stressor, the purpose of the study is to investigate the level of tolerance of chufa (Cyperus esculentus L.) plant communities grown in solutions based on mineralized human wastes to a damaging air temperature, 45 °C. Experiments were performed with 30-day-old chufa plant communities grown hydroponically, on expanded clay aggregate, under artificial light, at 690 μmol m⁻² s⁻¹ PAR and at a temperature of 25 °C. Plants were grown in Knop’s solution and solutions based on human wastes mineralized according to Yu.A. Kudenko’s method, which contained nitrogen either as ammonium and urea or as nitrates. The heat shock treatment lasted 20 h at 690 and 1150 μmol m⁻² s⁻¹ PAR. Chufa heat tolerance was evaluated based on parameters of CO₂ gas exchange, the state of its photosynthetic apparatus (PSA), and intensity of peroxidation of leaf lipids. Chufa plants grown in the solutions based on mineralized human wastes that contained ammonium and urea had lower heat tolerance than plants grown in standard mineral solutions. Heat tolerance of the plants grown in the solutions based on mineralized human wastes that mainly contained nitrate nitrogen was insignificantly different from the heat tolerance of the plants grown in standard mineral solutions. A PAR intensity increase from 690 μmol m⁻² s⁻¹ to 1150 μmol m⁻² s⁻¹ enhanced heat tolerance of chufa plant communities, irrespective of the conditions of mineral nutrition under which they had been grown.     

Processing of nutritious, safe and acceptable foods from CELSS candidate crops.

A controlled ecological life-support system (CELSS) is required to sustain life for long-duration space missions. The challenge is preparing a wide variety of tasty, familiar, and nutritious foods from CELSS candidate crops under space environmental conditions. Conventional food processing technologies will have to be modified to adapt to the space environment. Extrusion is one of the processes being examined as a means of converting raw plant biomass into familiar foods. A nutrition-improved pasta has been developed using cowpea as a replacement for a portion of the durum semolina. A freeze-drying system that simulates the space conditions has also been developed. Other technologies that would fulfill the requirements of a CELSS will also be addressed.     

Development of theoretical approaches to the control of a water-treatment system

The Advanced Life Support/NASA Specialized Center of Research and Training (ALS/NSCORT) focuses on research and development of technologies to support human habitation during space missions. This research was done as part of an effort to maintain crewmembers’ water supply in a closed life-support system. The water subsystem was the primary focus of this study because water is one of the most expensive and important resources for human survival.     

Subcritical and supercritical water oxidation of CELSS model wastes.

Controlled-Ecological-Life-Support-System (CELSS) model wastes were wet-oxidized at temperatures from 250 to 500 degrees C, i.e., below and above the critical point of water (374 degrees C and 218 kg/cm2 or 21.4 MPa). A solution of ammonium hydroxide and acetic acid and a slurry of human urine, feces, and wipes were used as model wastes. Almost all of the organic matter in the model wastes was oxidized in the temperature range from 400 to 500 degrees C, i.e., above the critical conditions for water. In contrast, only a small portion of the organic matter was oxidized at subcritical conditions. Although the extent of nitrogen oxidation to nitrous oxide (N2O) and/or nitrogen gas (N2) increased with reaction temperature, most of the nitrogen was retained in solution as ammonia near 400 degrees C. This important finding suggests that most of the nitrogen in the waste feed can be retained in solution as ammonia during oxidation at low supercritical temperatures and be subsequently used as a nitrogen source for plants in a CELSS while at the same time organic matter is almost completely oxidized to carbon dioxide and water. It was also found in this study the Hastelloy C-276 alloy reactor corroded during waste oxidation. The rate of corrosion was lower above than below the critical temperature for water.     

不确定理论下竞争失效系统的可靠性分析

针对有新研发产品，故障数据较少的复杂系统，提出了不确定环境下自然退化和外部冲击相互独立的竞争失效模型。考虑了系统同时遭受自然退化和外部冲击，连续的自然退化用一个不确定过程刻画，冲击到达的时间间隔和每次冲击对系统造成的损坏量分别用2个不同的不确定变量来刻画。运用不确定理论，分别在极端冲击模型、累积冲击模型、δ冲击模型下，研究了系统的确信可靠度，结果表明:在有新研发的产品、故障数据较少的复杂系统，用不确定理论的方法来描述模型更合适，并通过数值分析显示了模型的有效性。      

Use of human wastes oxidized to different degrees in cultivation of higher plants on the soil-like substrate intended for closed ecosystems

To close mass exchange loops in bioregenerative life support systems more efficiently, researchers of the Institute of Biophysics SB RAS (Krasnoyarsk, Russia) have developed a procedure of wet combustion of human wastes and inedible parts of plants using H₂O₂ in alternating electromagnetic field. Human wastes pretreated in this way can be used as nutrient solutions to grow plants in the phototrophic unit of the LSS. The purpose of this study was to explore the possibilities of using human wastes oxidized to different degrees to grow plants cultivated on the soil-like substrate (SLS). The treated human wastes were analyzed to test their sterility. Then we investigated the effects produced by human wastes oxidized to different degrees on growth and development of wheat plants and on the composition of microflora in the SLS. The irrigation solution contained water, substances extracted from the substrate, and certain amounts of the mineralized human wastes. The experiments showed that the human wastes oxidized using reduced amounts of 30% H₂O₂: 1 ml/g of feces and 0.25 ml/ml of urine were still sterile. The experiments with wheat plants grown on the SLS and irrigated by the solution containing treated human wastes in the amount simulating 1/6 of the daily diet of a human showed that the degree of oxidation of human wastes did not significantly affect plant productivity. On the other hand, the composition of the microbiota of irrigation solutions was affected by the oxidation level of the added metabolites. In the solutions supplemented with partially oxidized metabolites yeast-like microscopic fungi were 20 times more abundant than in the solutions containing fully oxidized metabolites. Moreover, in the solutions containing incompletely oxidized human wastes the amounts of phytopathogenic bacteria and denitrifying microorganisms were larger. Thus, insufficiently oxidized sterile human wastes added to the irrigation solutions significantly affect the composition of the microbiological component of these solutions, which can ultimately unbalance the system as a whole.     

月面广义资源探测及其原位利用技术构想

以载人登月场景下的月面资源精细化利用为目标,概述了月面资源探测与原位利用技术的国内外发展现状。针对未来载人登月探测任务规划以及确定预先研究目标的实际需求,提出了月面环境资源的广义分类和精细化利用思想,并以载人登月场景下的"人器机环境"系统为研究对象,细化了可在轨利用的资源、需带回地球的样本资源和人机废弃物资源等三类资源的拓扑组成。本着继承与创新兼顾、前瞻性与实用性包容的概念研究理念,重点阐述了宇航员人因主导的矿物资源勘查、月面环境条件的资源化利用、多态样本的采集、人机废弃物的循环利用等月面广义资源的探测与原位利用技术途径。     

Direct utilization of human liquid wastes by plants in a closed ecosystem.

Model experiments in phytotrons have shown that urea is able to cover 70% of the demand in nitrogen of the conveyer cultivated wheat. At the same time wheat plants can directly utilize human liquid wastes. In this article by human liquid wastes the authors mean human urine only. In a long-term experiment on "man-higher plants" system with two crewmen, plants covered 63 m2, with wheat planted to--39.6 m2. For 103 days, complete human urine (total amount--210.7 l) was supplied into the nutrient solution for wheat. In a month and a half NaCl supply into the nutrient solution stabilized at 0.9-1.65 g/l. This salination had no marked effect on wheat production. The experiment revealed the realistic feasibility to directly involve liquid wastes into the biological turnover of the life support system. The closure of the system, in terms of water, increased by 15.7% and the supply of nutrients for wheat plants into the system was decreased.     

Integration of In-Situ Resource Utilization into lunar/Mars exploration through field analogs

The ability to extract and process resources at the site of exploration into useful products such as propellants, life support and power system consumables, and radiation and rocket exhaust plume debris shielding, known as In-Situ Resource Utilization or ISRU, has the potential to significantly reduce the launch mass, risk, and cost of robotic and human exploration of space. The incorporation of ISRU into missions can also significantly influence technology selection and system development in other areas such as power, life support, and propulsion. For example, the ability to extract or produce large amounts of oxygen and/or water in-situ could minimize the need to completely close life support air and water processing system cycles, change thermal and radiation protection of habitats, and influence propellant selection for ascent vehicles and surface propulsive hoppers. While concepts and even laboratory work on evaluating and developing ISRU techniques such as oxygen extraction from lunar regolith have been going on since before the Apollo 11 Moon landing, no ISRU system has ever flown in space, and only recently have ISRU technologies been developed at a scale and at a system level that is relevant to actual robotic and human mission applications. Because ISRU hardware and systems have never been demonstrated or utilized before on robotic or human missions, architecture and mission planners and surface system hardware developers are hesitant to rely on ISRU products and services that are critical to mission and system implementation success. To build confidence in ISRU systems for future missions and assess how ISRU systems can best influence and integrate with other surface system elements, NASA, with international partners, are performing analog field tests to understand how to take advantage of ISRU capabilities and benefits with the minimum of risk associated with introducing this game-changing approach to exploration. This paper will describe and review the results of four analog field tests (Moses Lake in 6/08, Mauna Kea in 11/08, Flagstaff in 9/09, and Mauna Kea in 1/10) that have begun the process of integrating ISRU into robotic and human exploration systems and missions, and propose future ISRU-related analog field test activities that can be performed in collaboration with non-US space agencies.     

Potential of salt-accumulating and salt-secreting halophytic plants for recycling sodium chloride in human urine in bioregenerative life support systems

This study addresses the possibility of growing different halophytic plants on mineralized human urine as a way to recycle NaCl from human wastes in a bioregenerative life support system (BLSS). Two halophytic plant species were studied: the salt-accumulating Salicornia europaea and the salt-secreting Limonium gmelinii. During the first two weeks, plants were grown on Knop’s solution, then an average daily amount of urine produced by one human, which had been preliminarily mineralized, was gradually added to the experimental solutions. Nutrient solutions simulating urine mineral composition were gradually added to control solutions. NaCl concentrations in the stock solutions added to the experimental and control solutions were 9 g/L in the first treatment and 20 g/L in the second treatment. The mineralized human urine showed some inhibitory effects on S. europaea and L. gmelinii. The biomass yield of experimental plants was lower than that of control ones. If calculated for the same time period (120 d) and area (1 m²), the amount of sodium chloride taken up by S. europaea plants would be 11.7 times larger than the amount taken up by L. gmelinii plants (486 g/m² vs. 41 g/m²). Thus, S. europaea is the better choice of halophyte for recycling sodium chloride from human wastes in BLSS.     

Current concepts and future directions of CELSS.

Studies of bioregenerative life support systems for use in space indicate that they are scientifically feasible. Preliminary data suggest that they would provide cost- and weight-saving benefits for low Earth orbit, long duration space platforms. Concepts of such systems include the use of higher plants and/or micro-algae as sources of food, potable water and oxygen, and as sinks for carbon dioxide and metabolic wastes. Recycling of materials within the system will require processing of food organism and crew wastes using microbiological and/or physical chemical techniques. The dynamics of material flow within the system will require monitoring, control, stabilization and maintenance imposed by computers. Future phases of study will continue investigations of higher plant and algal physiology, environmental responses, and control; flight experiments for testing responses of organisms to weightlessness and increased radiation levels; and development of ground-based facilities for the study of recycling within a bioregenerative life support system.