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PubMed2001

Intracanopy lighting reduces electrical energy utilization by closed cowpea stands.

The high planting densities needed to grow edible biomass in sustainable space life support systems will create problems for planophile crops that form closed, self-shading canopies. The use of traditional overhead-lighting configurations will reduce the penetration of photosynthetically active radiation (PAR) into such canopies and will result in substantial shading of understory leaves. Intracanopy lighting, an irradiation approach that allows plants to grow around fixed arrays of low-intensity lamps, reduces overall energy expenditure for crop production by improving light distribution and interception throughout the canopy. Comparing different fluorescent lamp geometries within vegetative canopies of cowpea (Vigna unguiculata L. Walp) revealed great plasticity of leaf orientation to maximize absorption of PAR from lamps arrayed at various nontraditional angles. Varying the amount of photosynthetic energy available within canopies creates considerable potential to manipulate canopy productivity. Increasing lamp number 38% within cowpea canopies raised stand productivity 45%, reflecting the highly efficient interception and absorption of intracanopy PAR. However, combined above/within-canopy lighting did not increase overall PAR interception and vegetative yield, and productivity did not improve relative to the same input wattage of intracanopy lighting alone. Optimization of intracanopy lighting for crops to be used in future space life support systems will substantially reduce power and energy burdens for food-crop production.

Biomass↗
PubMed1998

Characterizations of high-intensity red and blue light-emitting diodes (LEDs) as a light source for plant growth.

Recently developed high-intensity red and blue light-emitting diodes (LEDs), which constitute a potentially improved light source for controlled-environment plant growth applications such as in vitro micropropagation and biologically based advanced life support (ALS) for space missions, were characterized in this study. Blue 2 LED and Red 1 LED consistently yielded the highest and lowest voltage drop readings, respectively, for all the electrical current settings tested (5-50 mA), with Blue 1 LED producing voltage drops falling nearly in the middle of the readings for the first two LEDs. At the standard current setting of 20 mA, Blue 2 LED and Blue 1 LED required 2.5 and 1.6 times more electrical power, respectively, than did Red 1 LED. At the standard current of 20 mA, the average photosynthetic photon flux (PPF) for Red 1 LED, Blue 1 LED, and Blue 2 LED were 180, 145, and 36 micromoles m-2 s-1, respectively. Red 1 LED peaked at 460 micromoles m-2 s-1 at 50 mA, Blue 1 LED at 200 micromoles m-2 s-1 at 40 mA, and Blue 2 LED at 40 micromoles m-2 s-1 at about 25 mA. For all current settings, the electrical conversion efficiency of Red 1 was approximately two times greater than that of Blue 1 LED. The electrical conversion efficiency of Blue 1 and of Red 1 LED peaked in between 10 and 20 mA, at about 13 mA for Blue 1 LED and at about 15 mA for Red 1 LED. The normalized PPF distributions for both Red 1 LED and Blue 1 LED were independent of the various magnitudes of electrical current (20, 30, 40, and 50 mA) that were applied to the LEDs.

Ecological Systems, Closed↗
PubMed1997

An integrated Engineered Closed/Controlled EcoSystem for a lunar base.

Long-term human missions in space, such as the establishment of a human-tended lunar base, require autonomous life support systems. A Lunar Engineered Closed/Controlled EcoSystem (LECCES) can provide autonomy by integrating a human module with support plant and animal modules, and waste treatment subsystems. Integration of physical/chemical (P/C) and biological waste treatment subsystems can lead to viable and operational bioregenerative systems that minimize resupply requirements from Earth. A top-level diagram for LECCES is developed based on the human module requirements. The proposed diagram is presented and its components are discussed.

Animals↗
PubMed2004

Online model-based diagnosis to support autonomous operation of an advanced life support system.

This article describes methods for online model-based diagnosis of subsystems of the advanced life support system (ALS). The diagnosis methodology is tailored to detect, isolate, and identify faults in components of the system quickly so that fault-adaptive control techniques can be applied to maintain system operation without interruption. We describe the components of our hybrid modeling scheme and the diagnosis methodology, and then demonstrate the effectiveness of this methodology by building a detailed model of the reverse osmosis (RO) system of the water recovery system (WRS) of the ALS. This model is validated with real data collected from an experimental testbed at NASA JSC. A number of diagnosis experiments run on simulated faulty data are presented and the results are discussed.

Algorithms↗
PubMed1994

Machine vision monitoring of plant health.

Techniques and algorithms to detect and diagnose disorders in plants grown in a controlled environment have been developed. A video camera senses features of plants which are indicative of disorders. Images are calibrated for size and color variations by using calibration templates. Different image segmentation techniques for separating object from background, have been implemented. Plant size and color properties have been investigated, temporal, spectral and spatial variation of leaves were extracted from the segmented images. Neural network and statistical classifiers were used to determine plant condition.

Algorithms↗
PubMed1997

Super-optimal CO2 reduces wheat yield in growth chamber and greenhouse environments.

Seven growth chamber trials (six replicate trials using 0.035, 0.12, and 0.25% CO2 in air and one trial using 0.12, 0.80, and 2.0% CO2 in air) and three replicate greenhouse trials (0.035, 0.10, 0.18, 0.26, 0.50, and 1.0% CO2 in air) compare the effects of super-optimal CO2 on the seed yield, harvest index, and vegetative growth rate of wheat (Triticum aestivum L. cvs. USU-Apogee and Veery-10). Plants in the growth chamber trials were grown hydroponically under fluorescent lamps, while the greenhouse trials were grown under sunlight and high pressure sodium lamps and in soilless media. Plants in the greenhouse trials responded similarly to those in the growth chamber trials; maximum yields occurred near 0.10 and 0.12% CO2 and decreased significantly thereafter. This research indicates that the toxic effects of elevated CO2 are not specific to only one environment and has important implications for the design of bio-regenerative life support systems in space, and for the future of terrestrial agriculture.

Biomass↗
PubMedDate not supplied

Evaluation of two fiber optic-based solar collection and distribution systems for advanced space life support.

Growing plants in an enclosed controlled environment is crucial in developing bioregenerative life-support systems (BLSS) for space applications. The major challenge currently facing a BLSS is the extensive use of highly energy-intensive electric light sources, which leads to substantial energy wastes through heat dissipations by these lamps. An alternative lighting strategy is the use of a solar irradiance collection, transmission, and distribution system (SICTDS). Two types of fiber optic-based SICTDS, a Fresnel-lens Himawari and a parabolic-mirror optical waveguide (OW) lighting system, were evaluated. The overall efficiency for the OW SICTDS of 40.5% exceeded by 75% that for the Himawari of 23.2%. The spectral distributions of the light delivered by the Himawari and the OW SICTDS were almost identical and had practically no difference from that of terrestrial solar radiation. The ratios of photosynthetically active radiation (PAR) to total emitted radiation (k) of 0.39 +/- 0.02 for the Himawari and 0.41 +/- 0.04 for the OW SICTDS were statistically indistinguishable, were not significantly different from that of 0.042 +/- 0.01 for terrestrial solar radiation, and were comparable to that of 0.35 for a high-pressure sodium (HPS) lamp. The coefficients of variation (CV) of 0.34 and 0.39 for PPF distributions, both at 50 mm X 50 mm square grid arrays, corresponding to the Himawari and the OW SICTDS, respectively, were comparable with each other but were both significantly greater than the CV of 0.08 corresponding to the HPS lamp. The average fresh weight or dry weight of lettuce grown in the solar chamber with either the Himawari or the OW SICTDS showed no statistical difference from the average fresh weight or dry weight of lettuce grown in the reference chamber with the HPS lamp. The results of this study suggest that an SICTDS could help reduce the electric power demand in a BLSS.

Ecological Systems, Closed↗
PubMed1997

In vitro food production for isolated closed environments: formation of ripe tomato fruits from excised flower buds.

Excised preanthesis flower buds of young Pixie Hybrid tomato plants develop into red ripe fruits in aseptic culture on a modified Murashige-Skoog medium with 3% sucrose at pH 5.8. The addition of certain synthetic auxins (IAA, NAA, IBA), auxin precursors (ISA), or cytokinins (KIN, IPA, ZEA, BAP) to the medium improved the percentage of buds developing into fruits, the weight of the ripe fruits, or both. The best results were obtained by an auxin-cytokinin combination of 10 microM IBA with 1 microM BAP. Storage of the excised buds at low temperature (6 degrees C) for up to 4 weeks before transfer to 27 degrees C caused only minimal deterioration in size and number of the fruit crop. Extension of low-temperature storage to 8 weeks produced smaller fruits that took longer to develop. This system could produce fresh, ripe small tomatoes on a sustained basis for up to 2 months for an isolated environment such as a space vehicle or submarine.

Adenine↗
PubMed1999

Composting on Mars or the Moon: I. Comparative evaluation of process design alternatives.

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 O2 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.

Biodegradation, Environmental↗
PubMed2000

Quality comparison of hydroponic tomatoes (Lycopersicon esculentum) ripened on and off vine.

There is a general belief that the quality of tomatoes ripened on vine is better than tomatoes ripened off the vine, influencing among other parameters, the price of this commodity. We compared the quality of hydroponic tomatoes ripened on and off vine by chemical, physical, and sensory evaluation to find what attributes are affected and to what extent. Lycopene, beta-carotene, total and soluble solids, moisture content, ascorbic acid, acidity, pH, texture, and color were analyzed. Tomatoes ripened on vine had significantly more lycopene, beta-carotene, soluble and total solids, higher a* and lower L*, and were firmer. However, a 100-judge panel rated only the color and overall liking of the vine-ripened tomatoes as more intense than the fruit ripened off vine. Therefore, the chemical and physical differences were mostly not large enough to influence the panelist's perception. The characterization of tomatoes ripened on and off vine may help to guide post-harvest handling and treatment and to improve the quality of tomatoes ripened off vine.

Ascorbic Acid↗
PubMedDate not supplied

Adaptation of SUBSTOR for controlled-environment potato production with elevated carbon dioxide.

The SUBSTOR crop growth model was adapted for controlled-environment hydroponic production of potato (Solanum tuberosum L. cv. Norland) under elevated atmospheric carbon dioxide concentration. Adaptations included adjustment of input files to account for cultural differences between the field and controlled environments, calibration of genetic coefficients, and adjustment of crop parameters including radiation use efficiency. Source code modifications were also performed to account for the absorption of light reflected from the surface below the crop canopy, an increased leaf senescence rate, a carbon (mass) balance to the model, and to modify the response of crop growth rate to elevated atmospheric carbon dioxide concentration. Adaptations were primarily based on growth and phenological data obtained from growth chamber experiments at Rutgers University (New Brunswick, N.J.) and from the modeling literature. Modified-SUBSTOR predictions were compared with data from Kennedy Space Center's Biomass Production Chamber for verification. Results show that, with further development, modified-SUBSTOR will be a useful tool for analysis and optimization of potato growth in controlled environments.

Biomass↗
PubMed1999

Food processing on a space station: feasibility and opportunities.

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.

Equipment Design↗
PubMed1998

Microwave lamp characterization.

The operating properties of the SAA microwave lamp developed by Fusion Lighting, Inc. were determined with reference to its usefulness in Bioregenerative Life Support Systems (BLSS). Lamp flux density in several wavelength ranges, spectral output, and temperature response (-10 to +40 degrees C) were determined by mounting the lamp and sensors in a controlled environment chamber. Lamp intensity distribution also was measured using a swing arm apparatus with a 1-m radius. A model was developed to characterize the intensity distribution of the lamp as a function of lamp geometry and output properties. The lamp was found to produce a spectral output similar to that of earlier lamp models, but with a higher photosynthetic output per lumen and per input watt. Radiant energy output was measured to be 0.399 radiant watts per micromole s-1 PAR compared with 0.56 radiant watts per micromoles s-1 PAR for high-pressure sodium lamps. Total lamp output dropped approximately 0.4% for every degree Celsius rise in ambient temperature, with little change in light quality. The intensity distribution of the lamp was found to produce a fairly uniform flux density (+/- 22%) in a 40 degrees cone from lamp nadir.

Ecological Systems, Closed↗
PubMed1999

Composting on Mars or the Moon: II. Temperature feedback control with top-wise introduction of waste material and air.

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.

Biodegradation, Environmental↗
PubMed1998

Advantages of Sabatier for extended duration manned missions.

As manned space missions become longer and go farther away (i.e., Mars missions), the cost of resupply missions becomes substantial and even impractical. In order to reduce the logistics penalty for air revitalization in manned spacecraft, breathing oxygen (O2) must be recovered from metabolic carbon dioxide (CO2). The Sabatier CO2 reduction system is a key component of an integrated air revitalization system. The heart of the Sabatier system is the chemical catalyst bed that reacts carbon dioxide with hydrogen to form methane and water. Product water from a Sabatier subsystem would positively affect the current International Space Station (ISS) water balance and Mars missions would also benefit from the use of product methane as a propellant. This article focuses on the potential benefits of using the Sabatier subsystem for ISS and potential Mars mission applications.

Air Conditioning↗
PubMed1999

Growing wheat in Biosphere 2 under elevated CO2: observations and modeling.

Spring wheat (Triticum aestivum L., cv. Yecora Rojo) was grown in the intensive agricultural biome (IAB) of Biosphere 2 during the l995-l996 winter/spring season. Environmental conditions were characterized by a day/night temperature regime of 27/17 degrees C, relative humidity (RH) levels around 45%, mean atmospheric CO2 concentration of 450 ppmv, and natural light conditions with mean intensities about half of outside levels. Weekly samples of above-ground plant matter were collected throughout the growing season and phenological events recorded. A computer model, CERES-Wheat, previously tested under both field and controlled conditions, was used to simulate the observed crop growth and to help in data analysis. We found that CERES-Wheat simulated the data collected at Biosphere 2 to within 10% of observed, thus suggesting that wheat growth inside the IAB was comparable to that documented in other environments. The model predicts phenological stages and final dry matter (DM) production within l0% of the observed data. Measured DM production rates, normalized for light absorbed by the crop. suggested photosynthetic efficiencies intermediate between those observed under optimal field conditions and those recorded in NASA-Controlled Ecological Life-Support Systems (CELSS). We suggest that such a difference can be explained primarily in terms of low light levels inside the IAB, with additional effects due to elevated CO2 concentrations and diffuse light fractions.

Agriculture↗