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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

A chamber design for closed ecological systems research

A single-plant growth chamber is described which is closed with respect to nutrient and gas flows, in order to serve as a tool in the investigation of control over biological systems. Such control procedures are essential for the use of biological components in the development of a closed ecological life support system (CELSS). The chamber's design consists of two concentric clear plastic cylinders equipped with aeroponic feed tubing, a supporting platform for the plant and a set of sensors that includes an anemometer, thermistors, pressure and strain gauges, and humidity sensors.

Schwartzkopf, H.↗
NASA NTRS1982

Ecological optimality in water-limited natural soil-vegetation systems. I - Theory and hypothesis

The solution space of an approximate statistical-dynamic model of the average annual water balance is explored with respect to the hydrologic parameters of both soil and vegetation. Within the accuracy of this model it is shown that water-limited natural vegetation systems are in stable equilibrium with their climatic and pedologic environments when the canopy density and species act to minimize average water demand stress. Theory shows a climatic limit to this equilibrium above which it is hypothesized that ecological pressure is toward maximization of biomass productivity. It is further hypothesized that natural soil-vegetation systems will develop gradually and synergistically, through vegetation-induced changes in soil structure, toward a set of hydraulic soil properties for which the minimum stress canopy density of a given species is maximum in a given climate. Using these hypotheses, only the soil effective porosity need be known to determine the optimum soil and vegetation parameters in a given climate.

Eagleson, P. S.↗
NASA NTRS1982

Controlled ecological life support system: Transportation analysis

This report discusses a study utilizing a systems analysis approach to determine which NASA missions would benefit from controlled ecological life support system (CELSS) technology. The study focuses on manned missions selected from NASA planning forecasts covering the next half century. Comparison of various life support scenarios for the selected missions and characteristics of projected transportation systems provided data for cost evaluations. This approach identified missions that derived benefits from a CELSS, showed the magnitude of the potential cost savings, and indicated which system or combination of systems would apply. This report outlines the analytical approach used in the evaluation, describes the missions and systems considered, and sets forth the benefits derived from CELSS when applicable.

Gustan, E.↗
NASA NTRS1982

Microbial ecology of extreme environments: Antarctic dry valley yeasts and growth in substrate-limited habitats

The success of the Antarctic Dry Valley yeasts presumeably results from adaptations to multiple stresses, to low temperatures and substrate-limitation as well as prolonged resting periods enforced by low water availability. Previous investigations have suggested that the crucial stress is substrate limitation. Specific adaptations may be pinpointed by comparing the physiology of the Cryptococcus vishniacii complex, the yeasts of the Tyrol Valley, with their congeners from other habitats. Progress was made in methods of isolation and definition of ecological niches, in the design of experiments in competition for limited substrate, and in establishing the relationships of the Cryptococcus vishniacii complex with other yeasts. In the course of investigating relationships, a new method for 25SrRNA homology was developed. For the first time it appears that 25SrRNA homology may reflect parallel or convergent evolution.

Vishniac, H. S.↗
NASA NTRS1984

Controlled ecological life support system higher plant flight experiments

Requirements for spaceflight experments which involve higher plants were determined. The plants are studied for use in controlled ecological life support systems (CELSS). Two categories of research requirements are discussed: (1) the physical needs which include nutrient, water and gas exchange requirements; (2) the biological and physiological functions which affect plants in zero gravity environments. Physical problems studies are given the priority since they affect all biological experiments.

Tibbitts, T. W.↗
NASA NTRS1985

The Controlled Ecological Life Support System

A Controlled Ecological Life Support System (CELSS) is needed which would convert waste water to usable water, waste products to food, and CO2 to O2 to permit long duration space flight. Algae, representing the autotroph, and mice, representing the heterotroph are placed together in a controlled, gas closed environment to examine the gas exchange rate of O2 and CO2. The eventual goal is to develop biological controls that can stabilize atmospheres.

Ko, K.↗
NASA NTRS1985

Controlled Ecological Life Support System. Life Support Systems in Space Travel

Life support systems in space travel, in closed ecological systems were studied. Topics discussed include: (1) problems of life support and the fundamental concepts of bioregeneration; (2) technology associated with physical/chemical regenerative life support; (3) projection of the break even points for various life support techniques; (4) problems of controlling a bioregenerative life support system; (5) data on the operation of an experimental algal/mouse life support system; (6) industrial concepts of bioregenerative life support; and (7) Japanese concepts of bioregenerative life support and associated biological experiments to be conducted in the space station.

Macelroy, R. D.↗
NASA NTRS1985

Publications of the NASA CELSS (Controlled Ecological Life Support Systems) program

Publications on research sponsored by the NASA CELSS (controlled ecological life support systems) Program are listed. The bibliography is divided into four areas: (1) human requirements; (2) food production; (3) waste management; and (4) system management and control. The 210 references cover the period from the inception of the CELSS Program (1979) to the present, as well as some earlier publications during the development of the CELSS Program.

Dufour, P. A.↗
NASA NTRS1985

Role of chemotaxis in the ecology of denitrifiers

It has been recognized that the process of denitrification represents a major sequence in the nitrogen cycle. It involves the anaerobic reduction of nitrate or nitrite to nitrous oxide or elemental nitrogen. This process is responsible for significant losses of nitrogen from agricultural soils. Up to now, little attention has been paid to the ecology of the organisms responsible for denitrification. It is pointed out that chemotaxis would probably offer a strong competitive mechanism for denitrifiers, since chemotaxis would allow denitrifiers to actively reach nitrate by directed motility, rather than by random movement or diffusion of nitrate. The present investigation was initiated to examine the chemotactic responses of several denitrifiers to nitrate and nitrite. Attention is given to bacterial strains, culture media and cell preparation, chemotaxis assays, and competition experiments. It was found that several denitrifiers, including P. aeruginosa, P. fluorescens, and P. Stutzeri, were strongly attracted to NO3(-) and NO2(-).

Kennedy, M. J.↗
NASA NTRS1986

Controlled Ecological Life Support Systems: CELSS 1985 Workshop

Various topics related to closed ecological systems are discussed. Space habitats, vegetative growth, photosynthesis, recycling, culture techniques, waste utilization bioreactors and controlled atmospheres on space stations are among the topics covered.

Macelroy, R. D.↗
NASA NTRS1986

The role of plant disease in the development of controlled ecological life support systems

Plant diseases could be important factors affecting growth of higher plants in Closed Ecological Life Support Systems (CELSS). Disease control, therefore, will be needed to maintain healthy plants. The most important controls should be aimed at preventing the introduction, reproduction and spread of pathogens and preventing plant infection. An integrared ease control program will maximize that approach. In the design and operation of CELSS, plant disease should be considered an important aspect of plant growth. The effects of plant diseases are reviewed and several disease control measures are discussed.

Nelson, B.↗
NASA NTRS1986

Development of space technology for ecological habitats

The development of closed ecological systems for space stations is discussed. Growth chambers, control systems, microgravity, ecosystem stability, lighting equipment, and waste processing systems are among the topics discussed.

Martello, N. V.↗
NASA NTRS1984

Controlled ecological life support systems for space habitats

The development of regenerative life support systems to meet the physiological requirements of humans in space is described. A review of previous research on regenerative systems is presented. NASA's Controlled Ecological Life Support System (CELSS) program, which is to develop an environment for a human space crew, is discussed. The table of physiological requirements of an average human and the logical system approach to planning a closed system created by Spurlock and Modell (1976, 1978) are examined. The weight of food and oxygen with respect to lift-off weight is investigated. The creation of the proper atmosphere for space, by balancing all the necessary parameters is studied. The need for a mineral and fluid balance and methods of maintaining it are analyzed. The required cooperation between physicians, physiologists, and nutritionists for the success of the CELSS program is discussed.

Buchanan, P.↗
NASA NTRS1986

The ecology of microorganisms in a small closed system: Potential benefits and problems for space station

The inevitble presence on the space station of microorganisms associated with crew members and their environment will have the potential for both benefits and a range of problems including illness and corrosion of materials. This report reviews the literature presenting information about microorganisms pertinent to Environmental Control and Life Support (ECLS) on the space station. The perspective of the report is ecological, viewing the space station as an ecosystem in which biological relationships are affected by factors such as zero gravity and by closure of a small volume of space. Potential sites and activities of microorganisms on the space station and their environmental limits, microbial standards for the space station, monitoring and control methods, effects of space factors on microorganisms, and extraterrestrial contamination are discussed.

Rodgers, E. B.↗
NASA NTRS1987

Publications of the NASA Controlled Ecological Life Support Systems (CELSS) Program 1984-86

Publications of research sponsored by the NASA CELSS (Controlled Ecological Life Support Systems) Program are listed, along with publications of interest to the Program. The bibliography is divided into the three major divisions of CELSS research: (1) Food Production; (2) Waste Management; and (3) Systems Management and Control. This bibliography is an update of NASA CR-3911 and includes references from 1984 through 1986.

Source record↗
NASA NTRS1987

Controlled Ecological Life Support System. Design, Development, and Use of a Ground-Based Plant Growth Module

Problems of food production by higher plants are addressed. Experimentation requirements and necessary equipment for designing an experimental Controlled Ecological Life Support System (CELSS) Plant Growth Module are defined. A framework is provided for the design of laboratory sized plant growth chambers. The rationale for the development of an informal collaborative effort between investigators from universities and industry and those at Ames is evaluated. Specific research problems appropriate for collaborative efforts are identified.

Macelroy, Robert D.↗