ognizant Communication Corporation

LIFE SUPPORT & BIOSPHERE SCIENCE

ABSTRACTS
VOLUME 8, NUMBERS 3\4

Life Support & Biosphere Science, Vol. 8, pp. 125-135
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Water Cycles in Closed Ecological Systems: Effects of Atmospheric Pressure

Vadim Y. Rygalov,1 Philip A. Fowler,2 Joannah M. Metz,3 Raymond M. Wheeler,4 and Ray A. Bucklin1

1University of Florida, Department of Agricultural and Biological Engineering, Rogers Hall, Museum Road, PO Box 110570, Gainesville, FL 32611-0570
2Dynamac Corporation, Mail Code DYN-3, Kennedy Space Center, FL 32899
3University of Illinois at Urbana-Champaign, Urbana, IL 61801
4NASA Biological Sciences Branch, Mail Code YA-D3, Kennedy Space Center, FL 32899

In bioregenerative life support systems that use plants to generate food and oxygen, the largest mass flux between the plants and their surrounding environment will be water. This water cycle is a consequence of the continuous change of state (evaporation<\#0150>condensation) from liquid to gas through the process of transpiration and the need to transfer heat (cool) and dehumidify the plant growth chamber. Evapotranspiration rates for full plant canopies can range from ~1 to 10 L m-2 d-1 (~1 to 10 mm m-2 d-1), with the rates depending primarily on the vapor pressure deficit (VPD) between the leaves and the air inside the plant growth chamber. VPD in turn is dependent on the air temperature, leaf temperature, and current value of relative humidity (RH). Concepts for developing closed plant growth systems, such as greenhouses for Mars, have been discussed for many years and the feasibility of such systems will depend on the overall system costs and reliability. One approach for reducing system costs would be to reduce the operating pressure within the greenhouse to reduce structural mass and gas leakage. But managing plant growth environments at low pressures (e.g., controlling humidity and heat exchange) may be difficult, and the effects of low-pressure environments on plant growth and system water cycling need further study. We present experimental evidence to show that water saturation pressures in air under isothermal conditions are only slightly affected by total pressure, but the overall water flux from evaporating surfaces can increase as pressure decreases. Mathematical models describing these observations are presented, along with discussion of the importance for considering "water cycles" in closed bioregenerative life support systems.

Key words: Water cycle; Low pressure; Evapotranspiration; Relative humidity; Vapor pressure deficit

Address correspondence to Vadim Y. Rygalov, University of Florida, Department of Agricultural and Biological Engineering, Rogers Hall, Museum Road, PO Box 110570, Gainesville, FL 32611-0570. Tel: (321) 476-4279 Fax: (321) 853-4165; E-mail: RygaLVE@kscems.ksc.hasa.gov




Life Support & Biosphere Science, Vol. 8, pp. 137-147
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Near-Term Lander Experiments for Growing Plants on Mars: Requirements for Information on Chemical and Physical Properties of Mars Regolith

Andrew C. Schuerger,1 Douglas W. Ming,2 Horton E. Newsom,3 Robert J. Ferl,4 and Christopher P. Mckay5

1Dynamac Corporation, Mail Code DYN-3, Kennedy Space Center, FL 32899
2Mail Code SX3, NASA Johnson Space Center, Houston, TX 77058
3University of New Mexico, Institute of Meteoritics and Department of Earth and Planetary Sciences, Albuquerque, NM 87131
4Biotechnology and Horticultural Sciences, University of Florida, Gainesville, FL 32611
5Space Science Division, Mail Stop 245-3, NASA Ames Research Center, Moffett Field, CA 94035

In order to support humans for long-duration missions to Mars, bioregenerative Advanced Life Support (ALS) systems have been proposed that would use higher plants as the primary candidates for photosynthesis. Hydroponic technologies have been suggested as the primary method of plant production in ALS systems, but the use of Mars regolith as a plant growth medium may have several advantages over hydroponic systems. The advantages for using Mars regolith include the likely bioavailability of plant-essential ions, mechanical support for plants, and easy access of the material once on the surface. We propose that plant biology experiments must be included in near-term Mars lander missions in order to begin defining the optimum approach for growing plants on Mars. Second, we discuss a range of soil chemistry and soil physics tests that must be conducted prior to, or in concert with, a plant biology experiment in order to properly interpret the results of plant growth studies in Mars regolith. The recommended chemical tests include measurements on soil pH, electrical conductivity and soluble salts, redox potential, bioavailability of essential plant nutrients, and bioavailability of phytotoxic elements. In addition, a future plant growth experiment should include procedures for determining the buffering and leaching requirements of Mars regolith prior to planting. Soil physical tests useful for plant biology studies in Mars regolith include bulk density, particle size distribution, porosity, water retention, and hydraulic conductivity.

Key words: Mars; Mars lander; Astrobiology; Soil chemistry; Plant biology

Address correspondence to Andrew C. Schuerger, Dynamac Corporation, Mail Code DYN-3, Kennedy Space Center, FL 32899. Tel: (321) 476-4261; Fax: (321) 853-4165; E-mail: schueac@kscems.ksc.nasa.gov
 




Life Support & Biosphere Science, Vol. 8, pp. 149-154
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Potential Integration of Wetland Wastewater Treatment with Space Life Support Systems

M. Nelson,1,2 A. Alling,2,3 W. F. Dempster,1,3 M. Van Thillo,2,3 and J. P. Allen1,2

1Institute of Ecotechnics, London, UK
2Biosphere Technologies, Santa Fe, NM
3Biosphere Foundation, Santa Fe, NM

Subsurface-flow constructed wetlands for wastewater treatment and nutrient recycling have a number of advantages in planetary exploration scenarios: they are odorless, relatively low labor and low energy, assist in purification of water and recycling of atmospheric CO2, and can directly grow some food crops. This article presents calculations for integration of wetland wastewater treatment with a prototype ground-based experimental facility ("Mars on Earth") supporting four people showing that an area of 4-6 m2 may be sufficient to accomplish wastewater treatment and recycling. Discharge water from the wetland system can be used as irrigation water for the agricultural crop area, thus ensuring complete reclamation and utilization of nutrients within the bioregenerative life support system. Because the primary requirements for wetland treatment systems are warm temperatures and lighting, such bioregenerative systems can be integrated into space life support systems because heat from the lights may be used for temperature maintenance in the human living environment. Subsurface-flow wetlands can be modified for space habitats to lower space and mass requirements. Many of its construction requirements can eventually be met with use of in situ materials, such as gravel from the Mars surface. Because the technology does not depend on machinery and chemicals, and relies more on natural ecological mechanisms (microbial and plant metabolism), maintenance requirements (e.g., pumps, aerators, and chemicals) are minimized, and systems may have long operating lifetimes. Research needs include suitability of Martian soil and gravel for wetland systems, system sealing and liner options in a Mars base, and determination of wetland water quality efficiency under varying temperature and light regimes.

Key words: Constructed wetlands; Sewage treatment; Biosphere 2; Mars on Earth; Water recycling; Nutrient reclamation; Subsurface flow; "Wastewater Gardens"

Address correspondence to Mark Nelson, 7 Silver Hills Road, Santa Fe, NM 87505. E-mail: marknelson1@cs.com
 




Life Support & Biosphere Science, Vol. 8, pp. 155-160
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Airtight Sealing a Mars Base

William F. Dempster

Biospheric Design, Inc., 26 Synergia Road, Santa Fe, NM 87505

Atmospheric leakage from a Mars base would create a demand for continuous or periodic replenishment, which would in turn require extraction or mining for oxygen and other gases from local resources and attendant equipment and energy requirements for such operations. It therefore becomes a high priority to minimize leakage. This article quantifies leak rates as determined by the size of holes and discusses the implications of pressure for structural configuration. The author engineered the sealing of Biosphere 2 from which comparisons are drawn.

Key words: Airtight; Sealing; Mars base; Leakage; Pressure

Address correspondence to William F. Dempster, Director of Systems Engineering, Biospheric Design, Inc., 26 Synergia Road, Santa Fe, NM 87508. Tel: (505) 438-9873; Fax: (505) 474-5269; E-mail: wfdempster@aol.com



 
Life Support & Biosphere Science, Vol. 8, pp. 161-172
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Light, Plants, and Power for Life Support on Mars

F. B. Salisbury,1 W. F. Dempster,2,3 J. P. Allen,2,3,4 A. Alling,3,4 D. Bubenheim,5 M. Nelson,2,3 And S. Silverstone3,4

1Prof. Emeritus, Plant, Soils, and Biometeorology Department, Utah State University, Logan, UT
2Institute of Ecotechnics, 24 Old Gloucester St., London WC1 3AL, UK
3Biosphere Technologies, (a division of Global Ecotechnics Corp.), 7 Silver Hills Rd, Santa Fe, NM 87508
4Biosphere Foundation, 9 Silver Hills Road, Santa Fe, NM 87508
5NASA Ames Research Center, Moffett Field, CA

Regardless of how well other growing conditions are optimized, crop yields will be limited by the available light up to saturation irradiances. Considering the various factors of clouds on Earth, dust storms on Mars, thickness of atmosphere, and relative orbits, there is roughly 2/3 as much light averaged annually on Mars as on Earth. On Mars, however, crops must be grown under controlled conditions (greenhouse or growth rooms). Because there presently exists no material that can safely be pressurized, insulated, and resist hazards of puncture and deterioration to create life support systems on Mars while allowing for sufficient natural light penetration as well, artificial light will have to be supplied. If high irradiance is provided for long daily photoperiods, the growing area can be reduced by a factor of 3-4 relative to the most efficient irradiance for cereal crops such as wheat and rice, and perhaps for some other crops. Only a small penalty in required energy will be incurred by such optimization. To obtain maximum yields, crops must be chosen that can utilize high irradiances. Factors that increase ability to convert high light into increased productivity include canopy architecture, high-yield index (harvest index), and long-day or day-neutral flowering and tuberization responses. Prototype life support systems such as Bios-3 in Siberia or the Mars on Earth Project need to be undertaken to test and further refine systems and parameters.

Key words: Mars; Crop yields; Wheat; Cereals; Photosynthetic photon flux; Light

Address correspondence to William F. Dempster, Director of Systems Engineering, Biospheric Design, Inc., 26 Synergia Road, Santa Fe, NM 87508. Tel: (505) 438-9873; Fax: (505) 474-5269; E-mail: wfdempster@aol.com




Life Support & Biosphere Science, Vol. 8, pp. 173-179
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Swiss Chard: A Salad Crop for the Space Program

Logan S. Logendra, Matthew R. Gilrain, Thomas J. Gianfagna, and Harry W. Janes

Plant Biology Department, Rutgers University, 59 Dudley Road, New Brunswick, NJ 08901-8520

Salad greens will be among the first crops grown on lunar or planetary space stations. Swiss chard (Beta vulgaris L.) is an important candidate salad crop because it is high yielding and rich in vitamins and minerals. Five Swiss chard cultivars were grown in the greenhouse under two light levels for 13 weeks to compare cumulative yields from weekly harvests, mineral composition, and to evaluate sensory attributes as a salad green. The varieties Large White Ribbed (LWR) and Lucullus (LUC) were the highest yielding in both light regimes. LWR was the shortest of the cultivars requiring the least vertical space. LWR also received the highest sensory ratings of the five cultivars. LWR Swiss chard should be considered as an initial test variety in food production modules.

Key words: Salad crops; Greens; Beta vulgaris L.; Controlled environment

Address correspondence to Logan S. Logendra, Plant Biology Department, Rutgers University, 59 Dudley Road, New Brunswick, NJ 08901-8520. E-mail: logendra@AESOP.RUTGERS.EDU




Life Support & Biosphere Science, Vol. 8, pp. 181-189
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Enzyme-Based Co2 Capture for Advanced Life Support

Jijun Ge,1 Robert M. Cowan,2 Chingkuang Tu,3 Martin L. Mcgregor,1 and Michael C. Trachtenberg1

1Sapient's Institute, Rutgers University, New Brunswick, NJ 08901
2Rutgers University, Department of Environmental Science, NJ NSCORT, New Brunswick, NJ 08901
3Department of Pharmacology, University of Florida School of Medicine, Gainesville, FL 32610

Elevated CO2 levels in air can lead to impaired functioning and even death to humans. Control of CO2 is critical in confined spaces that have little physical or biological buffering capacity (e.g., spacecraft, submarines, or aircraft). A novel enzyme-based contained liquid membrane bioreactor was designed for CO2 capture and certain application cases are reported in this article. The results show that the liquid layer accounts for the major transport resistance. With addition of carbonic anhydrase, the transport resistance decreased by 71%. Volatile organic compounds of the type and concentration expected to be present in either the crew cabin or a plant growth chamber did not influence carbonic anhydrase activity or reactor operation during 1-day operation. Alternative sweep method studies, examined as a means of eliminating consumables, showed that the feed gas could be used successfully in a bypass mode when combined with medium vacuum pressure (-85 kPa) to achieve CO2 separation comparable to that with an inert sweep gas. The reactor exhibited a selectivity for CO2 versus N2 of 1400:1 and CO2 versus O2 is 866:1. The CO2 permeance was 1.44 x 10-7 mol m-2 Pa-1 s-1 (4.3 x 10-4 cm3 cm-2 s-1 cmHg-1) at a feed concentration of 0.1% CO2. These data show that the enzyme-based contained liquid membrane is a promising candidate technology that may be suitable for NASA applications to control CO2 in the crew or plant chambers.

Key words: Carbon dioxide; Carbonic anhydrase; Bioreactor; Contained liquid membrane; Gas separation

Address correspondence to M. C. Trachtenberg, Sapient's Institute, 20A g Extension Way, Bioresource Engineering Group, Cook College/Rutgers University, New Brunswick, NJ 08901-8500. Tel: (732) 932-8875; Fax: (732) 932-7931; E-mail: miket@aesop.rutgers.edu




Life Support & Biosphere Science, Vol. 8, pp. 191-197
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A Management Information System to Study Space Diets*

Sukwon Kang1 and A. J. Both2

1USDA, BARC, ANRI, Instrumentation and Sensing Laboratory, Bldg. 303, BARC-East, 10300 Baltimore Ave., Beltsville, MD 20705
2Bioresource Engineering, Department of Plant Biology and Pathology, Rutgers, the State University of New Jersey, 20 Ag Extension Way, New Brunswick, NJ 08901-8500

A management information system (MIS), including a database management system (DBMS) and a decision support system (DSS), was developed to dynamically analyze the variable nutritional content of foods grown and prepared in an Advanced Life Support System (ALSS) such as required for long-duration space missions. The DBMS was designed around the known nutritional content of a list of candidate crops and their prepared foods. The DSS was designed to determine the composition of the daily crew diet based on crop and nutritional information stored in the DBMS. Each of the selected food items was assumed to be harvested from a yet-to-be designed ALSS biomass production subsystem and further prepared in accompanying food preparation subsystems. The developed DBMS allows for the analysis of the nutrient composition of a sample 20-day diet for future Advanced Life Support missions and is able to determine the required quantities of food needed to satisfy the crew's daily consumption. In addition, based on published crop growth rates, the DBMS was able to calculate the required size of the biomass production area needed to satisfy the daily food requirements for the crew. Results from this study can be used to help design future ALSS for which the integration of various subsystems (e.g., biomass production, food preparation and consumption, and waste processing) is paramount for the success of the mission.

Key words: Advance Life Support System (ALSS); Food nutritional analysis; Database management system (DBMS); Decision support system (DSS); Optimization; Linear programming

Address correspondence to Sukwon Kang, USDA, BARC, ANRI, Instrumentation and Sensing Laboratory, Bldg. 303, BARC-East, 10300 Baltimore Ave., Beltsville, MD 20705. Tel: + (301) 504-8450; Fax: (301) 504-9466; E-mail: kangs@ba.ars.usda.gov

*Presented as Paper No. 01-3021 at the 2001 ASAE Annual International Meeting, July 30- August 1, 2001, Sacramento, CA. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the Rutgers, the State University of New Jersey. New Jersey Agricultural Experiment Station Publication No. D-70501-03-02.




Life Support & Biosphere Science, Vol. 8, pp. 199-210
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Bioregenerative Food System Cost Based on Optimized Menus for Advanced Life Support

Geoffrey C. R. Waters,1 Ammar Olabi,2 Jean B. Hunter,3 Mike A. Dixon,1 and Christophe Lasseur4

1University of Guelph, Department of Plant Agriculture, Division of Horticultural Science, E.C. Bovey Building, Guelph, Ontario, Canada, N1G 2W1
2Department of Food Science and 3Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853-2801
4European Space Agency-ESTEC, Thermal Control and Life Support Division, Keplerlaan 1, 2200 AG Noordwijk, The Netherlands

Optimized menus for a bioregenerative life support system have been developed based on measures of crop productivity, food item acceptability, menu diversity, and nutritional requirements of crew. Crop-specific biomass requirements were calculated from menu recipe demands while accounting for food processing and preparation losses. Under the assumption of staggered planting, the optimized menu demanded a total crop production area of 453 m2 for six crew. Cost of the bioregenerative food system is estimated at 439 kg per menu cycle or 7.3 kg ESM crew-1 day-1, including agricultural waste processing costs. On average, about 60% (263.6 kg ESM) of the food system cost is tied up in equipment, 26% (114.2 kg ESM) in labor, and 14% (61.5 kg ESM) in power and cooling. This number is high compared to the STS and ISS (nonregenerative) systems but reductions in ESM may be achieved through intensive crop productivity improvements, reductions in equipment masses associated with crop production, and planning of production, processing, and preparation to minimize the requirement for crew labor.

Key words: Equivalent system mass; Bioregenerative life support; Food systems; Menu planning

Address correspondence to Geoffrey C. R. Waters, University of Guelph, Department of Plant Agriculture, Division of Horticultural Science, E.C. Bovey Building, Guelph, Ontario, Canada, N1G 2W1. Tel: (519) 824-4120, x8395; Fax: (519) 767-0755; E-mail: waters@ces.uoguelph.ca