ognizant Communication Corporation

LIFE SUPPORT & BIOSPHERE SCIENCE

ABSTRACTS
VOLUME 6, NUMBERS 1-3, 1999

Life Support & Biosphere Science, Vol. 6, pp. 1-3, 1999
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Nutrition and Food Concerns for Long-Term Space Travel: Recommendations for Research

Adria R. Sherman1 and Yael Vodovotz2

1Department of Nutritional Sciences, NJ-NASA Specialized Center of Research & Training, Rutgers University, 106 Thompson Hall, 96 Lipman Drive, New Brunswick, NJ 08901-8525
2NASA-JSC/University of Houston, Mail Code SP4, NASA-Johnson Space Center, Houston, TX 77058

In order to establish a research agenda for nutrition and food concerns associated with long-duration space travel, a conference was sponsored by the New Jersey-NASA Specialized Center of Research & Training (NJ-NSCORT), NASA, and the University of Houston Conrad N. Hilton College of Hotel & Restaurant Management. Invited papers were presented and are published in this special issue. Following intensive panel discussions and workshops the participants developed recommendations for a research agenda. The recommendations are listed in this introductory article.

Key words: Nutrition Food; Mars mission; Physical and mental health

Address correspondence to Adria R. Sherman, Ph.D. Tel: (732) 932-6530; Fax: (732) 932-6837.



Life Support & Biosphere Science, Vol. 6, pp. 5-8, 1999
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Nutritional Biochemistry of Space Flight

Scott M. Smith1 and Helen W. Lane2

1Nutritional Biochemistry Laboratory, Life Sciences Research Laboratories, and 2Space and Life Sciences Directorate, NASA Johnson Space Center, Houston, TX 77058

Humans have flown in space for more than 35 years. Since that time, Americans have walked on the moon, launched two space stations (Skylab and the International Space Station), docked during orbit with a Soviet Soyuz space capsule and the Russian Mir space station, flown the only reusable space vehicle, and visited a Russian space station for more than 6 months at a time. Nutritional intake has not been considered a high priority during relatively brief flights of the Space Shuttle and other programs (i.e., less than 21 days). However, as we embark on extended-duration (i.e., less than 30 days up to several years) missions, nutrition becomes a critical issue. The impact of weightlessness on human physiology is profound. We are in the very early stages of understanding how space flight affects nutrient requirements and related issues such as absorption, metabolism, and excretion. Apart from the obvious role of providing energy and required nutrients, nutrition is also important in terms of enhancing psychosocial interactions among crews, and ameliorating some of the effects of microgravity on the body (i.e., acting as a "countermeasure"). The interrelationships among space flight, nutrition, and physiology suggest that a program of specified nutritional intake may be required to enhance mission safety and crew productivity. Defining which nutrients are essential for space flight environment depends on a more complete understanding of how weightlessness affects physiology. Providing the required nutrients is also limited by the types of foods that can be provided by the food system on board the space craft, and the dietary habits of space crews.

Key words: Diet; Weightlessness; Microgravity; Nutrient requirements

Address correspondence to Scott M. Smith, Ph.D., Mail Code SD3, NASA Johnson Space Center, Houston, TX 77058. Tel: (281) 483-7204; Fax: (281) 483-2888; E-mail: smsmith@ems.jsc.nasa.gov



Life Support & Biosphere Science, Vol. 6, pp. 9-12, 1999
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Food Systems for Space Travel

Charles T. Bourland

NASA Johnson Space Center, Houston, TX 77058

Space food systems have evolved from tubes and cubes to Earth-like food being planned for the International Space Station. The weight, volume, and oxygen-enriched atmosphere constraints of earlier spacecraft severely limited the type of food that could be used. Food systems improved as spacecraft conditions became more habitable. Space food systems have traditionally been based upon the water supply. This presentation summarizes the food development activities from Mercury through Shuttle, Shuttle/Mir, and plans for the International Space Station. Food development lessons learned from the long-duration missions with astronauts on the Mir station are also discussed. Nutritional requirements for long-duration missions in microgravity and problems associated with meeting these requirements for Mir will be elucidated. The psychological importance of food and the implications for food development activities are summarized.

Key words: Shuttle; Mir; Space food

Address correspondence to Charles T. Bourland. Tel: (281) 483-3632; Fax: (281) 483-1847.



Life Support & Biosphere Science, Vol. 6, pp. 19-27, 1999
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Perspective on the Consequences of Short- and Long-Duration Space Flight on Human Physiology

M. F. Holick

Vitamin D, Skin, and Bone Research Laboratory, Section of Endocrinology, Nutrition, and Diabetes in the Department of Medicine, Boston University Medical Center, Boston, MA 02118

During the past three decades, humans have made significant progress in accomplishing their aspirations for exploring the Moon and the planets. It is now appreciated that humans undergo a remarkable number of physiologic adaptations in microgravity that affect most physiologic systems. Space motion sickness was one of the first adaptations that humans experienced in microgravity. However, it is self-limiting and, most of the time, is effectively treated pharmacologically. Of particular concern is that, in microgravity, there is marked wasting of the skeletal musculature and skeleton that appears to be unrelenting and could impact on the health and welfare of space travelers during prolonged space flights and on return to earth. Microgravity also has a significant impact on the cardiovascular system that could have potentially serious consequences in terms of cardiovascular health during long-duration space flights. Other adaptations such as decreased T-cell responsiveness and changes in circadian rhythms is only now being explored. We need to understand the role that microgravity has on human physiologic systems in order to develop strategies for permitting humans to experience prolonged microgravity without having significant impact on their health and welfare. Engineering some gravitational force as a component of long-duration space vehicles should be given a high priority.

Key words: Human physiology; Microgravity; Skeletal musculature

Address correspondence to M. F. Holick, Ph.D., M.D.



Life Support & Biosphere Science, Vol. 6, pp. 29-33, 1999
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Long-Term Acceptability of Limited Diets

Zata Vickers

Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Ave, St. Paul, MN 55108

A food with long-term acceptability can be eaten one or more times a day without the consumer becoming "tired" of eating it. Few foods are eaten as often as once a day, but those that are can give us some clues about the attributes associated with long-term acceptability. Studies by the armed forces in the late 1950s showed that most foods decreased in liking when repeatedly consumed and that the rate of decline depended on the specific food. Current techniques for measuring the liking of foods (typically using a hedonic category scale) do not necessarily indicate long-term acceptability. Our data on repeated consumption of two versions of tea suggests that taste test measurements can be quite misleading. A relatively newer measurement, sensory-specific satiety, may provide a rapid method for measuring long-term acceptability.

Key words: Food acceptability; Long-term acceptability; Sensory-specific satiety; Taste tests

Address correspondence to Zata Vickers, Ph.D. Tel: (612) 624-2257; Fax: (612) 625-5272; E-mail: vicke002@tc.umn.edu



Life Support & Biosphere Science, Vol. 6, pp. 35-38, 1999
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Psychological and Behavioral Health Issues of Long-Duration Space Missions

Daniel J. Eksuzian

Human Behavior and Performance Group, Medical Operations Branch, Wyle Life Sciences, Inc., Mail Code HMF/P2, 1290 Hercules Dr., Suite 120, Houston, TX 77058

It will be the responsibility of the long-duration space flight crew to take the actions necessary to maintain their health and well-being and to cope with medical emergencies without direct assistance from support personnel, including maintaining mental health and managing physiological and psychological changes that may impair decision making and performance. The Behavior and Performance Integrated Product Team at Johnson Space Center, working within the Space Medicine, Monitoring, and Countermeasures Program, has identified critical questions pertaining to long-duration space crew behavioral health, psychological adaptation, human factors and habitability, and sleep and circadian rhythms. Among the projects addressing these questions are: the development of tools to assess cognitive functions during space missions; the development of a model of psychological adaptation in isolated and confined environments; tools and methods for selecting individuals and teams well-suited for long-duration missions; identification of mission-critical tasks and performance evaluation; and measures of sleep quality and correlation to mission performance.

Key words: Medicine; Cognitive; Psychology; Adaptation; Monitoring; Countermeasures

Address correspondence to Christopher Flynn, M.D., F. S., Mail Code SD26, NASA Johnson Space Center, 2101 NASA Road 1, Houston, TX 77058. Tel: (281) 483-7146.



Life Support & Biosphere Science, Vol. 6, pp. 39-52, 1999
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Food Processing on a Space Station: Feasibility and Opportunities

Dmitriy V. Zasypkin and Tung-Ching Lee

Cook College, Department of Food Science and the Center for Advanced Food Technology, Rutgers University, 65 Dudley Road, New Brunswick, NJ 08901-8520

An alternative strategy for processing plants into food on a space or other isolated station including an Advanced Life Support (ALS) system is proposed. Regular gravity (1 G) or hypogravity <1 G) has been considered. A key feature of this strategy is to include not only kitchen-scale preparation and processing but small-scale advanced food processing such as thermoplastic extrusion, homogenization, centrifugation, fermentation, etc. These processes are flexible and multifunctional and could significantly increase the variety, palatability, nutritional value, and shelf stability of foods, and the number of menu items based on ALS crops. The processes would minimize the time to process the food items and provide psychological support for the crew. The periodic processing of various crop harvests into shelf-stable foods for long-term storage can be performed. Unit operations as illustrated by various processing flow sheets on the manufacturing of individual products will be discussed in association with the equipment.

Key words: Life support; Food; Processing; Space

Address correspondence to Tung-Ching Lee. Tel: (732) 932-9611, ext. 236; Fax: (732) 932-6776; E-mail: lee@aesop.rutgers.edu



Life Support & Biosphere Science, Vol. 6, pp. 53-60, 1999
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Engineering Concepts for Food Processing in Bioregenerative Life Support Systems

Jean B. Hunter

Department of Agricultural and Biological Engineering, Cornell University, Ithaca, NY 14853

Long-duration manned missions, such as Mars exploration, will require development of new and cost-effective food production and delivery systems. Requirements for both carry-on preserved food and food processed from on-board crops exceed the capabilities of existing food processing and preservation technologies. For the transit phase, new food products, preservation methods, and processing technologies for ground-based food processing are required. The bioregenerative surface phase requires methods for processing of in situ-grown crops, treatment of food wastes, preparation of daily meals, and design of nutritious and appealing plant-based menus, all within severe cost and labor constraints. In design of the food supply for a long-term mission, the designers must select and apply both the packaged food and in situ processing technologies most appropriate for the specific mission requirements. This study aims to evaluate the strengths and weaknesses of different food system strategies in the context of different types of mission, and to point out the most important areas for future technology development.

Key words: Food processing; Long-duration missions; Preservation technology

Address correspondence to Jean B. Hunter. Tel: (607) 255-2297; Fax: (607) 255-4080; E-mail: jbh5@cornell.edu



Life Support & Biosphere Science, Vol. 6, pp. 61-66, 1999
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Food Safety and Sanitation During an Extended Mission

Dawn L. Hentges

Bowling Green State University, Department of Family and Consumer Sciences, Bowling Green, OH 43403

In preparation for future Lunar/Mars habitats, a food system is being developed at NASA-JSC to provide Advanced Life Support for long-duration missions. As much as 90% of the food consumed on these missions is expected to be grown, processed, and prepared in space. Conversion of crops to edible foods will require extensive food processing within the closed environment of the Bioregenerative Planetary Life Support System Test Complex (BIO-Plex). Identification of hazards and critical control points associated with water recycling, biomass management, use of multifunctional equipment, and possible concentration of toxic substances in the closed system is essential for the development of safe food processing techniques and equipment. A food safety analysis, using a Hazard Analysis Critical Control Point (HACCP) approach, was conducted to identify potential hazards and critical control points during food processing of BIO-Plex-produced lettuce and wheat.

Key words: Food processing; Food safety; HACCP; Hazard analysis

Address correspondence to Dawn Hentges. Tel: (419) 372-8090; Fax: (419) 372-7854.




Life Support & Biosphere Science, Vol. 6, pp. 67-71, 1999
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Extraction and Use of Nutrients From Composted Wheat and Potato Plants

Cheryl F. Atkinson,1 Jumoke K. Alim,2 Colleen A. Loader,3 and John C. Sager1

1NASA, Kennedy Space Center, FL 32899
2Morehouse College, Atlanta, GA 30314
3Dynamac Corporation, DYN-3, Kennedy Space Center, FL 32899

Human survival on extended-duration space missions will require reliable regenerative life support systems. Biological systems using higher plants could be incorporated into life support systems; however, substantial quantities of inedible crop residues will also be produced. Composting can reduce the volume of crop residues and provide an end product that may be leached to remove soluble nutrients for use in hydroponic plant growth systems. Solubilization can be affected by physical conditions; we investigated several treatments (pH, temperature, agitation, or pretreatment sonication) for aqueous extraction of nutrients from composted inedible potato and wheat biomass. No significant differences were noted in electrical conductivity data. Chemical analyses indicated highly significant differences. Wheat seeds (Triticum aestivum L. cv. Apogee) were germinated in each extract to monitor for potentially inhibitory compounds. Seeds germinated in each extract, but total mean root lengths were affected negatively by sonication before extraction. Aqueous extracts may also support plant growth.

Key words: Bioregenerative life support systems; Leaching; Physical conditions; Chemical analyses; Seed germination assay

Address correspondence to Cheryl F. Atkinson, NRC Resident Research Associate at NASA, Mail Code JJ-G, Kennedy Space Center, FL 32899. Tel: (407) 853-3405; Fax: (407) 853-4165.




Life Support & Biosphere Science, Vol. 6, pp. 73-85, 1999
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Computer Model of Hydroponics Nutrient Solution pH Control Using Ammonium

Marvin Pitts1 and Gary Stutte2

1Biological Systems Engineering, 209 L. J. Smith Hall, Washington State University, Pullman, WA 99164-6120
2Mail Code DYN-3, Dynamac Corp., Kennedy Space Center, FL 32899

A computer simulation of a hydroponics-based plant growth chamber using ammonium to control pH was constructed to determine the feasibility of such a system. In nitrate-based recirculating hydroponics systems, the pH will increase as plants release hydroxide ions into the nutrient solution to maintain plant charge balance. Ammonium is an attractive alternative to traditional pH controls in an ALSS, but requires careful monitoring and control to avoid overdosing the plants with ammonium. The primary advantage of using NH4+ for pH control is that it exploits the existing plant nutrient uptake charge balance mechanisms to maintain solution pH. The simulation models growth, nitrogen uptake, and pH of a 1-m2 stand of wheat. Simulation results indicated that ammonium-based control of nutrient solution pH is feasible using a proportional integral controller. Use of a 1 mmol/L buffer (Ka = 1.6 x 10-6) in the nutrient solution is required.

Key words: Ammonium; Hydroponics; pH control; Computer simulation

Address correspondence to Marvin Pitts. Tel: (509) 335-3243; Fax: (509) 335-2722; E-mail: pitts@wsu.edu




Life Support & Biosphere Science, Vol. 6, pp. 87-95, 1999
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Development of Expanded Extrusion Food Products for an Advanced Life Support System

Dmitriy V. Zasypkin and Tung-Ching Lee

Department of Food Science and Center for Advanced Food Technology, Rutgers University, 65 Dudley Road, New Brunswick, NJ 08901-8520

Extrusion processing was proposed to provide texture and to expand the variety of cereal food products in an isolated Advanced Life Support (ALS) system. Rice, wheat, and soy are the baseline crops selected for growing during long-term manned space missions. A Brabender single-screw laboratory extruder (model 2003, L/D 20:1), equipped with round nozzles of various lengths, was used as a prototype of a small-size extruder. Several concepts were tested to extend the variety and improve the quality of the products, to decrease environmental loads, and to promote processing stability. These concepts include: the blending of wheat and soybean flour, the extrusion of a coarser rice flour, separation of wheat bran, and optimization of the extruder nozzle design. An optimal nozzle length has been established for the extrusion of rice flour. Bran separating was necessary to improve the quality of wheat extrudates.

Key words: Extrusion; Advanced life support; Food; Rice; Wheat

Address correspondence to Prof. Tung-Ching Lee. Tel: (732) 932-9611, ext. 236; Fax: (732) 932-6776; E-mail: lee@aesop.rutgers.edu




Life Support & Biosphere Science, Vol. 6, pp. 97-106, 1999
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Ground-Based Studies and Space Experiment With Potato Leaf Explants

Theodore W. Tibbitts,1 Judith C. Croxdale,1 Christopher S. Brown,2 Raymond M. Wheeler,3 and Gregory D. Goins4

1University of Wisconsin, Madison, WI 53706
2Dynamac Corp, Durham, NC 27713
3NASA Kennedy Space Ctr. FL 32899
4Dynamac Corp, Kennedy Space Ctr. FL 32899

This article details the extensive preflight research required to make a plant experiment conform to the constraints imposed by the spaceflight system. Potato explants, each consisting of a leaf, an axillary bud, and small stem section, were flown on USML-2 in the ASTROCULTURETM flight hardware to study tuber formation from the axillary bud during the 16 days of flight. To obtain acceptable explant materials: 1) parent plants had to be grown under reduced light (150 mmol m-2 s-1 PPF) to ensure uniform bud and tuber development, 2) leaves had to be trimmed to fit the small size of the flight growth chamber, and 3) only young, fully expanded leaves from plants 5-7 weeks old could be used. After six scrubs, the experiment was flown successfully October 20 to November 5 and produced tubers and accumulated starch similar to that produced on ground controls.

Key words: Potatoes; Tuberization; Life support; Preflight studies; USML-2

Address correspondence to Theodore W. Tibitts. Tel: (608) 262-1490; Fax: (608) 262-4743; E-mail: twt@facstaff.wis.edu




Life Support & Biosphere Science, Vol. 6, pp. 107-114, 1999
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Zinc Bioavailability in Young Adult Rats Fed Sweet Potato Greens Containing Phytic Acid

Sheldon E. Gordon, Aurea M. Almazan, Samuel O. Adeyeye, and Raphenia D. Pace

Department of Food and Nutritional Science, College of Agricultural, Environmental and Natural Sciences, Tuskegee University, Tuskegee, AL 36088

This study determined whether phytic acid in sweet potato greens influences the bioavailability of zinc in young adult rats used as models for adult humans. A control diet (AIN-93M), two AIN-93M diets with pure phytic acid (PA) at 0.2% or 0.4%, and four diets with Georgia Jet or TU-82-155 dried blanched greens at 7.5% or 15% were fed to seven groups of 7-week male Harlan-Sprague rats for 21 days. Weight gains were generally not affected by PA concentration, were lower in the rats fed with sweet potato greens than in the control rats, and were similar in the rats fed with pure PA or control diet. Feed intake utilization, as indicated by the total weight gain per total feed intake, was almost similar in the different rat groups. Bone (femur, tibia) and organ (kidney, liver, lung, spleen) weights, except the heart weights, were similar for all diet groups. Their zinc concentrations were generally not affected by PA concentration but depended on the PA source.

Key words: Sweet potato greens; Phytic acid; Zinc bioavailability; Young adult male Harlan-Sprague rats; Georgia Jet sweet potato; TU-82-155 sweet potato

Address correspondence to Aurea M. Almazan. E-mail: ALMAZAH@acd.tusk.edu




Life Support & Biosphere Science, Vol. 6, pp. 123-131, 1999
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Optimum Control of Closed Ecological Systems: Mathematical Aspects

Sergey I. Bartsev

Institute of Biophysics, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, 660036 Russia

Optimum control of a closed ecological system (CES) is not possible without adequate CES description and appropriate evaluation of factors, which act upon the system and introduce additional errors and uncertainties into the forecast of the CES state. The statement about key significance of stationary state consideration for further CES development is supported. In this article some of the disturbing stationary state factors and the contribution of them to CES state formation are considered. An approach to outlining the optimum set of chemical elements--the balance of which has to be calculated--is presented. An example of the minimum description of CES stationary state is considered.

Key words: Closed ecological system (CES); CES control; CES forecast precision; CES minimum description

Address correspondence to Sergey I. Bartsev, Ph.D. Fax: (3912) 433400.




Life Support & Biosphere Science, Vol. 6, pp. 133-139, 1999
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Experimental Models of Small Closed Systems With Spatially Separated Unicellular Organism-Based Components

T. I. Pis'man, N. S. Pechurkin, A. B. Sarangova, and L. A. Somova

Institute of Biophysics (Russian Academy of Sciences, Siberian Branch), Krasnoyarsk, Russia

Experimental models of small biotic cycles of different degree of closure and complexity with spatially separated components based on unicellular organisms have been studied. Gas closure of components looped into "autotroph-heterotroph" (chlorella-yeast) system doubled the lifetime of the system (as opposed to individually cultivated components). Higher complexity of the heterotroph component consisting of two yeast species also increased the lifetime of the system through more complete utilization of the substrate by competing yeast species. The lifetime of gas and substrate closed "producer-consumer" trophic chain (chlorella-paramecia) increased to 7 months. In 60 days the components' numbers reached their steady state followed by more than 40 cycles of the medium. The role of a predator organism (protozoan) in nitrogen cycling was demonstrated; reproduction of protozoa correlated directly with their emission of nitrogen in the ammonia form that is most optimum for growth of chlorella.

Key words: Small closed ecosystems; Autotroph; Heterotroph; Producer; Consumer; Spatially separated components

Address correspondence to T. I. Pis'man. Tel: 7 391 243 4623 or 7 391 222 1159.




Life Support & Biosphere Science, Vol. 6, pp. 141-152, 1999
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Direct Recycling of Human Hygiene Water Into Hydroponic Plant Growth Systems

Colleen A. Loader,1 Jay L. Garland,1 Lanfang H. Levine,1 Kim L. Cook,1 Cheryl L. Mackowiak,2 and Hollie R. Vivenzio1

1Dynamic Corporation, Mail Code DYN-3, Kennedy Space Center, FL 32899
2Department of Plant, Soils, and Biometeorology, Utah State University, Logan, UT 84322-4820

Direct recycling of gray water (human hygiene water) through plant production systems would reduce the need for additional space, mass, and energy for water reclamation in Advanced Life Support (ALS) systems. A plant production system designed to produce 25% of crew food needs could theoretically purify enough water through transpiration for 100% of crew water requirements. This scenario was tested through additions of shower and laundry water to recirculating hydroponic systems containing either wheat or soybean. Surfactant (Igepon TC-42) did not accumulate in the systems, and both the rate of surfactant disappearance and the proportion of Igepon-degrading microorganisms on the plant roots increased with time. A mechanism of surfactant degradation via the microbially mediated hydrolysis of the amide linkage and subsequent breakdown of fatty acid components is proposed. Fecal coliforms present in the human gray water were not detectable on the plant roots, indicating that human-associated microorganisms do not grow in the system. Overall plant growth was unaffected by gray water additions, although preliminary evidence suggests that reproduction may be inhibited.

Key words: Gray water recycling; Surfactant degradation; Wheat; Soybean; Igepon; Advanced Life Support (ALS); Bioregenerative Life Support System (BLSS); Controlled Ecological Life Support System (CELSS)

Address correspondence to Jay Garland. Tel: (407) 853-3148; Fax: (407) 853-4220.




Life Support & Biosphere Science, Vol. 6, pp. 153-160, 1999
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Recycling of Na in Advanced Life Support: Strategies Based on Crop Production Systems

Subbarao V. Guntur,1 Cheryl Mackowiak,2 and Raymond M. Wheeler3

1US National Research Council, 2Dynamac Corp., and 3NASA Biological Operations and Life Support, Kennedy Space Center, FL 32899

Sodium is an essential dietary requirement in human nutrition, but seldom holds much importance as a nutritional element for crop plants. In Advanced Life Support (ALS) systems, recycling of gases, nutrients, and water loops is required to improve system closure. If plants are to play a significant role in recycling of human wastes, Na will need to accumulate in edible tissues for return to the crew diet. If crops fail to accumulate the incoming Na into edible tissues, Na could become a threat to the hydroponic food production system by increasing the nutrient solution salinity. Vegetable crops of Chenopodiaceae such as spinach, table beet, and chard may have a high potential to supply Na to the human diet, as Na can substitute for K to a large extent in metabolic processes of these crops. Various strategies are outlined that include both genetic and environmental management aspects to optimize the Na recovery from waste streams and their resupply through the human diet in ALS.

Key words: Chenopods; Na recycling; Nutrient recycling; Strategies; Vegetable crops

Address correspondence to Subbarao V. Guntur. Tel: (407) 853-3404; Fax: (407) 853-4165; E-mail: subbagv%kscgws00@kmail.ksc.nasa.gov




Life Support & Biosphere Science, Vol. 6, pp. 161-167, 1999
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Insects at Low Pressure: Applications to Artificial Ecosystems and Implications for Global Windborne Distribution

Charles Cockell,1 David Catling,2 and Hilary Waites3

1M/S 239-20, NASA Ames Research Center, Moffett Field, CA 94035-1000
2M/S 245-3, NASA Ames Research Center, Moffett Field, CA 94035-1000
3Department of Biological Sciences, Stanford University, Stanford, CA 94305-5020

Insects have a number of potential roles in closed-loop life support systems. In this study we examined the tolerance of a range of insect orders and life stages to drops in atmospheric pressure using a terrestrial atmosphere. We found that all insects studied could tolerate pressures down to 100 mb. No effects on insect respiration were noted down to 500 mb. Pressure toleration was not dependent on body volume. Our studies demonstrate that insects are compatible with plants in low-pressure artificial and closed-loop ecosystems. The results also have implications for arthropod colonization and global distribution on Earth.

Key words: Insects; Ecosystems; Greenhouse; Mars; Subambient; Respiration; Chamber

Address correspondence to Charles Cockell. Tel: (650) 604-5499; E-mail: ccockell@mail.arc.nasa.gov




Life Support & Biosphere Science, Vol. 6, pp. 169-179, 1999
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Composting on Mars or the Moon: I. Comparative Evaluation of Process Design Alternatives

Melvin S. Finstein,1 Peter F. Strom,1,2 John A. Hogan,1,2 and Robert M. Cowan1,2

1Department of Environmental Sciences, New Jersey Agricultural Experiment Station
2NJ-NSCORT, Cook College, The State University of New Jersey, New Brunswick, NJ

As a candidate technology for treating solid wastes and recovering resources in bioregenerative Advanced Life Support, composting potentially offers such advantages as compactness, low mass, near ambient reactor temperatures and pressures, reliability, flexibility, simplicity, and forgiveness of operational error or neglect. Importantly, the interactions among the physical, chemical, and biological factors that govern composting system behavior are well understood. This article comparatively evaluates five Generic Systems that describe the basic alternatives to composting facility design and control. These are: 1) passive aeration; 2) passive aeration abetted by mechanical agitation; 3) forced aeration--O2 feedback control; 4) forced aeration--temperature feedback control; 5) forced aeration--integrated O and temperature feedback control. Each of the five has a distinctive pattern of behavior and process performance characteristics. Only Systems 4 and 5 are judged to be viable candidates for ALS on alien worlds, though which is better suited in this application is yet to be determined.

Key words: Bioregenerative life support; Waste treatment/resource recovery; Composting reactor design alternatives; Literature review

Address correspondence to Melvin S. Finstein, Rutgers University, Cook College, Department of Environmental Sciences, New Brunswick, NJ 08903. Tel: (732) 932-9735; Fax: (732) 932-8644; E-mail: finstein@envsci.rutgers.edu




Life Support & Biosphere Science, Vol. 6, pp. 181-191, 1999
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Composting on Mars or the Moon: II. Temperature Feedback Control With Top-Wise Introduction of Waste Material and Air

Melvin S. Finstein,1 John A. Hogan,1,2 John C. Sager,3 Robert M. Cowan,1,2 and Peter F. Strom1,2

1Department of Environmental Sciences, New Jersey Agricultural Experiment Station
2NJ-NSCORT, Cook College, Rutgers The State University of New Jersey, New Brunswick, NJ
3Life Science and Space Biology, NASA Kennedy Space Center, MD-RES, KSC, FL 32899

Whereas Earth-based composting reactors that effectively control the process are batch operations with bottom-to-top airflow, in extraterrestrial application both the fresh waste and the air need to be introduced from above. Stabilized compost and used air would exit below. This materials flow pattern permits the addition of waste whenever generated, obviating the need for multiple reactors, and the incorporation of a commode in the lid. Top loading in turn dictates top-down aeration, so that the most actively decomposing material (greatest need for heat removal and O2 replenishment) is first encountered. This novel material and aeration pattern was tested in conjunction with temperature feedback process control. Reactor characteristics were: working volume, 0.15 m3; charge, 2 kg dry biomass per day (comparable to a 3-4 person self-sufficient bioregenerative habitat); retention time, 7 days. Judging from temperature profile, O2 level, air usage, pressure head loss, moisture, and odor, the system was effectively controlled over a 35-day period. Dry matter disappearance averaged 25% (10-42%). The compost product was substantially, though not completely, stabilized. This demonstrates the compatibility of top-wise introduction of waste and air with temperature feedback process control.

Key words: Bioregenerative ALS; Solid waste treatment/resource recovery; Realistic scale composting reactor; Composting process design and control

Address correspondence to Melvin S. Finstein, Rutgers University, Cook College, Department of Environmental Sciences, New Brunswick, NJ 08903. Tel: (732) 932-9735; Fax: (732) 932-8644; E-mail: finstein@envsci.rutgers.edu




Life Support & Biosphere Science, Vol. 6, pp. 193-197, 1999
1069-9422/99 $10.00 + .00
Copyright © 1999 Cognizant Comm. Corp.
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Experimental Microcosms as Models of Natural Ecosystems for Monitoring Survival of Genetically Modified Microorganism

L. Yu Popova, N. S. Pechurkin, E. E. Maksimova, T. V. Kargatova, T. Yu Krylova, T. I. Lobova, and A. N. Boyandin

Institute of Biophysics (Russian Academy of Sciences, Siberian Branch), Krasnoyarsk, 660036 Russia

An experimental approach for investigation of genetically modified microorganisms (GMMO) introduced into model ecosystems to evaluate potential risk of propagation of recombinant plasmids in surrounding medium has been developed. The object of modeling was Escherichia coli Z905 strain with a recombinant plasmid with bacterial luminescence genes, which was introduced into water microcosms of different structure. The approach involves comprehensive investigation of GMMO at four hierarchical levels: molecular (retaining the structure of the plasmid and expression of cloned genes); cellular (variation of metabolic activity); population (competitive power and metabolic interactions of GMMO with indigenous microflora, migration of recombinant and natural plasmids); ecosystem (effect of GMMO and cloned genes on ecosystem parameters). The experimental evidence and theoretical estimates are intended to form grounds to develop a basic version of an ecological certificate for different GMMO variants.

Key words: Genetically modified microorganisms; Model ecosystems; Natural ecosystems

Address correspondence to L. Yu Popova. Fax: +7 3912433400; E-mail: lubg@post.krascince.rssi.ru or lena@ibp.kzasnoyazsk.su




Life Support & Biosphere Science, Vol. 6, pp. 199-207, 1999
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Structural and Functional Changes in Photosynthetic Apparatus of Wheat Under Exposure to Sulfur Dioxide Fumes

O. V. Parshina And V. Ye Rygalov

Institute of Biophysics (Russian Academy of Sciences, Siberian Branch), Krasnoyarsk, 660036 Russia

Changes in photosynthesis of wheat (pigment content and chlorophyll fluorescence) have been measured to study effect of gaseous sulfur dioxide on wheat cenosis. Several biochemical and biophysical techniques have been estimated to evaluate their ability for early detection of destructive effect of  SO2. A mathematical model of toxic gas absorption in a closed system with plants has been proposed.

Key words: Effect of SO2; Photosynthetic apparatus of plants; Pigments; Fluorescence; Mathematical model; Closed system; Absorption of  SO2

Address correspondence to O. V. Parshina. Fax: +7 3912433400; E-mail: ibp@ibp.kzasnoyazsk.su




Life Support & Biosphere Science, Vol. 6, pp. 215-220, 1999
1069-9422/99 $10.00 + .00
Copyright © 1999 Cognizant Comm. Corp.
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Small Artificial Ecosystems: Response to Variation of Environmental Factors (Co2 Enrichment)

L. A. Somova,1 N. S. Pechurkin,1 A. B. Sarangova,1 T. I. Pisman,1 V. I. Polonsky,1 and G. M. Sadovskay2

1Institute of Biophysics and 2Computing Modeling Institute (Russian Academy of Sciences, Siberian Branch), Krasnoyarsk, 660036 Russia

Response of "wheat plants-rhizospheric microorganisms-artificial soil"--a simple terrestrial ecosystem--to carbon dioxide increased in its atmosphere to 0.06% has been studied. It has been experimentally demonstrated that a simple ecosystem develops and functions different from its individual elements (components), in this case "plants-artificial soil" without microorganisms. With mineral nutrition unlimited and CO2 enrichment the system is capable of binding (involving into turnover) 40% more carbon than the system without microorganisms. With material balance as the basis, this article evaluates the contribution of a system's elements into its development, namely, the contribution of the photosynthesizing component and the contribution of microorganisms.

Key words: Artificial ecosystems; Environmental factors; CO2 enrichment; Response to variation

Address correspondence to L. A. Somova. Fax: +7 3912433400




Life Support & Biosphere Science, Vol. 6, pp. 221-230, 1999
1069-9422/99 $10.00 + .00
Copyright © 1999 Cognizant Comm. Corp.
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A Method for the Imbibition and Germination of Wheat Seeds in Space

Howard G. Levine and William C. Piastuch

Gravitational Biology Laboratory, Dynamic Corporation, Mail Code DYN-3, Kennedy Space Center, FL 32899

A method was developed for the reliable germination in space of wheat seeds on porous tube nutrient delivery systems. Germination paper strips were loosely rolled into cylinders and two seeds inserted close to the outer edges of each cylinder. This configuration: 1) directed the emerging shoots upward and roots downward, 2) was efficient in wicking moisture from the porous tubes, and 3) provided open areas for oxygen diffusion. Cotton tufts were inserted into the bottom crevices of the cylinders to fix the seeds in a mid-level position and cylinders were then storable (indefinitely) prior to the preprogrammed (on-orbit) initiation of imbibition. This method extends both the upper and lower ends of acceptable moisture levels for successful seed germination, increasing the probability of success for spaceflight applications where moisture availability is more variable than on Earth.

Key words: Wheat; Seeds; Germination; Imbibition; Space Shuttle; Porous Tubes

Address correspondence to Howard G. Levine. Tel: (470) 853-7703; Fax: (407) 853-4220.




Life Support & Biosphere Science, Vol. 6, pp. 231-238, 1999
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Copyright © 1999 Cognizant Comm. Corp.
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Crop Biomass Leaching for Nutrient Recycling in a CELSS

Edie S. Sears and Paul N. Walker

The Pennsylvania State University, 249 Agricultural Engineering Building, University Park, PA 16802

Leaching may be employed as a biomass conversion technique to minimize consumption of system resources in a CELSS. This study examined leaching rates and total leachability of Triticum aestivum L. Yecora Rojo residue. Total biomass reduction and phosphate concentration in the leachate were tested as a function of particle size, leaching time of solid, temperature, and sonication versus mechanical agitation. For modeling purposes, phosphate rate constants were determined experimentally via batch testing on 25-mm biomass. Simulation models were written to predict the effect of liquid flow rate on phosphate leaching in cocurrent and countercurrent reactors.

Key words: Yecora Rojo; Sonication; Fine grinding; Countercurrent reactor

Address correspondence to Edie S. Sears, M.S. Tel: (814) 863-8233; Fax: (814) 863-1031; E-mail: ess124@psu.edu




Life Support & Biosphere Science, Vol. 6, pp. 239-249, 1999
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Copyright © 1999 Cognizant Comm. Corp.
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Assessment of Oxygen Levels in Alternative Designs of Semiclosed Underwater Breathing Apparatus

M. L. Nuckols,1 J. R. Clarke,2 and W. J. Marr1

1U. S. Naval Academy, 590 Holloway Road, Annapolis, MD 21402
2Navy Experimental Diving Unit, Panama City, FL 32407

A method for predicting the circuit oxygen levels in semiclosed underwater breathing apparatus (UBAs) is presented. Oxygen levels are assessed for traditional circuit designs using sonic metering valves to inject a constant mass flow of fresh makeup gas, as well as two alternative respiration-rate-coupled gas dosage designs using demand injection valves. The impact of variations in diver depth, activity level, gas injection rate, circuit volume, and makeup gas composition on these circuit oxygen levels is demonstrated. Respiration-coupled, demand gas delivery systems are shown to have significantly reduced circuit oxygen variations over a wide range of diver activity levels when compared to constant mass flow injection systems. Additionally, the respiration-coupled designs are shown to have potential reduced gas usage at low diver activity levels, resulting in longer mission duration capability, when compared to constant mass injection systems.

Key words: Underwater breathing apparatus (UBA); Oxygen levels; Respiration-coupled system

Address correspondence to M. L. Nuckols. Tel: (410) 293-6429; Fax: (410) 293-2219; Email: nuckols@nadn.navy.mil




Life Support & Biosphere Science, Vol. 6, pp. 251-258, 1999
1069-9422/99 $10.00 + .00
Copyright © 1999 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.

Advanced Dive Monitoring System

Wayne I. Sternberger and Stuart A. Goemmer

The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723-6099

The US Navy supports deep diving operations with a variety of mixed-gas life support systems. A systems engineering study was conducted for the Naval Experimental Dive Unit (Panama City, FL) to develop a concept design for an advanced dive monitoring system. The monitoring system is intended primarily to enhance diver safety and secondarily to support diving medicine research. Distinct monitoring categories of diver physiology, life support system, and environment are integrated in the monitoring system. A system concept is proposed that accommodates real-time and quantitative measurements, noninvasive physiological monitoring, and a flexible and expandable implementation architecture. Human factors and ergonomic design considerations have been emphasized to assure that there is no impact on the diver's primary mission. The Navy has accepted the resultant system requirements and the basic design concept. A number of monitoring components have been implemented and successfully support deep diving operations.

Key words: Diving; Hyperbaric; Monitoring; Physiology; Life support

Address correspondence to Wayne I. Sternberger, Ph.D. Tel: (240) 228-5086; Fax: (240) 228-5928.