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Dynamics of microorganism populations in recirculating nutrient solutions

This overview covers the basic microbial ecology of recirculating hydroponic solutions. Examples from NASA and Soviet Controlled Ecological Life Support Systems (CELSS) tests and the commercial hydroponic industry will be used. The sources of microorganisms in nutrient solutions include air, water, seeds, plant containers and plumbing, biological vectors, and personnel. Microbial fates include growth, death, and emigration. Important microbial habitats within nutrient delivery systems are root surfaces, hardware surfaces (biofilms), and solution suspension. Numbers of bacteria on root surfaces usually exceed those from the other habitats by several orders of magnitude. Gram negative bacteria dominate the microflora with fungal counts usually much lower. Trends typically show a decrease in counts with increasing time unless stressed plants increase root exudates. Important microbial activities include carbon mineralization and nitrogen transformations. Important detrimental interactions include competition with plants, and human and plant pathogenesis.

Strayer, R. F.↗

Environmental and cultural considerations for growth of potatoes in CELSS

The white potato (Solanum tuberosum) was evaluated for use in the Closed Ecology Life Support System (CELSS) because of its high ratio of edible to inedible biomass and highly nutritious tuber that consists of readily digestible carbohydrates and proteins. Results are given for conditions that will produce the highest yields. The results, given in tabluar form, indicate the optimum temperatures, irradiance, carbon dioxide concentration, root environment, plant spacing, root and stolen containment, and harvesting times.

Tibbitts, Theodore W.↗

The use of wood for wind turbine blade construction

The interrelationships between moisture and wood, conditions for dry rot spore activity, the protection of wood fibers from moisture, wood resin composites, wood laminating, quality control, and the mechanical properties of wood are discussed. The laminated veneer and the bonded sawn stock fabrication techniques, used in the construction of a turbine blade with a monocoque 'D' section forming the leading edge and a built up trailing edge section, are described. A 20 foot root end sample complete with 24 bonded-in studs was successfully subjected to large onetime loads in both the flatwise and edgewise directions, and to fatigue tests. Results indicate that wood is both a viable and advantageous material for use in wind turbine blades. The basic material is reasonably priced, domestically available, ecologically sound, and easily fabricated with low energy consumption.

Gougeon, M.↗

Skill Assessment of a Spectral Ocean-Atmosphere Radiative Model

Ocean phytoplankton, detrital material, and water absorb and scatter light spectrally. The Ocean- Atmosphere Spectral Irradiance Model (OASIM) is intended to provide surface irradiance over the oceans with sufficient spectral resolution to support ocean ecology, biogeochemistry, and heat exchange investigations, and of sufficient duration to support inter-annual and decadal investigations. OASIM total surface irradiance (integrated 200 nm to 4 microns) was compared to in situ data and three publicly available global data products at monthly 1-degree resolution. OASIM spectrally-integrated surface irradiance had root mean square (RMS) difference= 20.1 W/sq m (about 11%), bias=1.6 W/sq m (about 0.8%), regression slope= 1.01 and correlation coefficient= 0.89, when compared to 2322 in situ observations. OASIM had the lowest bias of any of the global data products evaluated (ISCCP-FD, NCEP, and ISLSCP 11), and the best slope (nearest to unity). It had the second best RMS, and the third best correlation coefficient. OASIM total surface irradiance compared well with ISCCP-FD (RMS= 20.7 W/sq m; bias=-11.4 W/sq m, r=0.98) and ISLSCP II (RMS =25.2 W/sq m; bias= -13.8 W/sq m; r=0.97), but less well with NCEP (RMS =43.0 W/sq m ;bias=-22.6 W/sq m; x=0.91). Comparisons of OASIM photosynthetically available radiation (PAR) with PAR derived from SeaWiFS showed low bias (-1.8 mol photons /sq m/d, or about 5%), RMS (4.25 mol photons /sq m/d ' or about 12%), near unity slope (1.03) and high correlation coefficient (0.97). Coupled with previous estimates of clear sky spectral irradiance in OASIM (6.6% RMS at 1 nm resolution), these results suggest that OASIM provides reasonable estimates of surface broadband and spectral irradiance in the oceans, and can support studies on ocean ecosystems, carbon cycling, and heat exchange.

Gregg, Watson, W.↗

Dynamics of microorganism populations in recirculating nutrient solutions

This overview covers the basic microbial ecology of recirculating hydroponic solutions. Examples from NASA and Soviet CELSS tests and the commercial hydroponic industry will be used. The sources of microorganisms in nutrient solutions include air, water, seeds, plant containers and plumbing, biological vectors, and personnel. Microbial fates include growth, death, and emigration. Important microbial habitats within nutrient delivery systems are root surfaces, hardware surfaces (biofilms), and solution suspension. Numbers of bacteria on root surfaces usually exceed those from the other habitats by several orders of magnitude. Gram negative bacteria dominate the microflora with fungal counts usually much lower. Trends typically show a decrease in counts with increasing time unless stressed plants increase root exudates. Important microbial activities include carbon mineralization and nitrogen transformations. Important detrimental interactions include competition with plants, and human and plant pathogenesis.

Strayer, R. F.↗

Regenerative Life Support Systems Test Bed performance - Lettuce crop characterization

Two crops of lettuce (Lactuca sativa cv. Waldmann's Green) were grown in the Regenerative Life Support Systems (RLSS) Test Bed at NASA's Johnson Space Center. The RLSS Test Bed is an atmospherically closed, controlled environment facility for the evaluation of regenerative life support systems using higher plants. The chamber encloses 10.6 m 2 of growth area under cool-white fluorescent lamps. Lettuce was double seeded in 480 pots, each containing about 250 cm 3 of calcined-clay substrate. Each pot was irrigated with half-strength Hoagland's nutrient solution at an average total applied amount of 2.5 and 1.8 liters pot -1 , respectively, over each of the two 30-day crop tests. Average environmental and cultural conditions during both tests were 23°C air temperature, 72% relative humidity, 1000 ppm carbon dioxide (CO 2 ), 16h light/8h dark photoperiod, and 356 μmol m -2 s -1 photosynthetic photon flux. After 30 days from seeding, average yield (g pot -1 ) for the first and second crop tests were 72 and 49 edible (shoot) fresh mass, 3.65 and 2.56 edible dry mass, and 0.44 and 0.45 inedible (root) dry mass, respectively. Averaging over both crop tests, the test bed met the requirements of 2.1 person-days of oxygen production, 2.4 person days of CO 2 removal and 129 person days of potential potable water production. The satisfactory growth of both crops demonstrates the potential of lettuce for air revitalization and water production in a controlled ecological life support system. Differences in crop performance resulting from engineering system effects provides evidence of the resilience of biological systems.

Life support systems↗

Toward applied behavior analysis of life aloft

This article deals with systems at multiple levels, at least from cell to organization. It also deals with learning, decision making, and other behavior at multiple levels. Technological development of a human behavioral ecosystem appropriate to space environments requires an analytic and synthetic orientation, explicitly experimental in nature, dictated by scientific and pragmatic considerations, and closely approximating procedures of established effectiveness in other areas of natural science. The conceptual basis of such an approach has its roots in environmentalism which has two main features: (1) knowledge comes from experience rather than from innate ideas, divine revelation, or other obscure sources; and (2) action is governed by consequences rather than by instinct, reason, will, beliefs, attitudes or even the currently fashionable cognitions. Without an experimentally derived data base founded upon such a functional analysis of human behavior, the overgenerality of "ecological systems" approaches render them incapable of ensuring the successful establishment of enduring space habitats. Without an experimentally derived function account of individual behavioral variability, a natural science of behavior cannot exist. And without a natural science of behavior, the social sciences will necessarily remain in their current status as disciplines of less than optimal precision or utility. Such a functional analysis of human performance should provide an operational account of behavior change in a manner similar to the way in which Darwin's approach to natural selection accounted for the evolution of phylogenetic lines (i.e., in descriptive, nonteleological terms). Similarly, as Darwin's account has subsequently been shown to be consonant with information obtained at the cellular level, so too should behavior principles ultimately prove to be in accord with an account of ontogenetic adaptation at a biochemical level. It would thus seem obvious that the most productive conceptual and methodological approaches to long-term research investments focused upon human behavior in space environments will require multidisciplinary inputs from such wide-ranging fields as molecular biology, environmental physiology, behavioral biology, architecture, sociology, and political science, among others.

Review↗

Monitoring Land Surface Albedo and Vegetation Dynamics Using High Spatial and Temporal Resolution Synthetic Time Series from Landsat and the MODIS BRDF/NBAR/Albedo Product

Seasonal vegetation phenology can significantly alter surface albedo which in turn affects the global energy balance and the albedo warmingcooling feedbacks that impact climate change. To monitor and quantify the surface dynamics of heterogeneous landscapes, high temporal and spatial resolution synthetic time series of albedo and the enhanced vegetation index (EVI) were generated from the 500-meter Moderate Resolution Imaging Spectroradiometer (MODIS) operational Collection V006 daily BRDF (Bidirectional Reflectance Distribution Function) / NBAR (Nadir BRDF-Adjusted Reflectance) / albedo products and 30-meter Landsat 5 albedo and near-nadir reflectance data through the use of the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM). The traditional Landsat Albedo (Shuai et al., 2011) makes use of the MODIS BRDFAlbedo products (MCD43) by assigning appropriate BRDFs from coincident MODIS products to each Landsat image to generate a 30-meter Landsat albedo product for that acquisition date. The available cloud free Landsat 5 albedos (due to clouds, generated every 16 days at best) were used in conjunction with the daily MODIS albedos to determine the appropriate 30-meter albedos for the intervening daily time steps in this study. These enhanced daily 30-meter spatial resolution synthetic time series were then used to track albedo and vegetation phenology dynamics over three Ameriflux tower sites (Harvard Forest in 2007, Santa Rita in 2011 and Walker Branch in 2005). These Ameriflux sites were chosen as they are all quite nearby new towers coming on line for the National Ecological Observatory Network (NEON), and thus represent locations which will be served by spatially paired albedo measures in the near future. The availability of data from the NEON towers will greatly expand the sources of tower albedometer data available for evaluation of satellite products. At these three Ameriflux tower sites the synthetic time series of broadband shortwave albedos were evaluated using the tower albedo measurements with a Root Mean Square Error (RMSE) less than 0.013 and a bias within the range of 0.006. These synthetic time series provide much greater spatial detail than the 500 meter gridded MODIS data, especially over more heterogeneous surfaces, which improves the efforts to characterize and monitor the spatial variation across species and communities. The mean of the difference between maximum and minimum synthetic time series of albedo within the MODIS pixels over a subset of satellite data of Harvard Forest (16 kilometers by 14 kilometers) was as high as 0.2 during the snow-covered period and reduced to around 0.1 during the snow-free period. Similarly, we have used STARFM to also couple MODIS Nadir BRDF-Adjusted Reflectances (NBAR) values with Landsat 5 reflectances to generate daily synthetic times series of NBAR and thus Enhanced Vegetation Index (NBAR-EVI) at a 30-meter resolution. While normally STARFM is used with directional reflectances, the use of the view angle corrected daily MODIS NBAR values will provide more consistent time series. These synthetic times series of EVI are shown to capture seasonal vegetation dynamics with finer spatial and temporal details, especially over heterogeneous land surfaces.

Vegetation Index↗

Suitability of Gray Water for Hydroponic Crop Production Following Biological and Physical Chemical and Biological Subsystems

The water present in waste streams from a human habitat must be recycled in Controlled Ecological Life Support Systems (CELSS) to limit resupply needs and attain self-sufficiency. Plants play an important role in providing food, regenerating air, and producing purified water via transpiration. However, we have shown that the surfactants present in hygiene waste water have acute toxic effects on plant growth (Bubenheim et al. 1994; Greene et al., 1994). These phytotoxic affects can be mitigated by allowing the microbial population on the root surface to degrade the surfactant, however, a significant suppression (several days) in crop performance is experienced prior to reaching sub-toxic surfactant levels and plant recovery. An effective alternative is to stabilize the microbial population responsible for degradation of the surfactant on an aerobic bioreactor and process the waste water prior to utilization in the hydroponic solution (Wisniewski and Bubenheim, 1993). A sensitive bioassay indicates that the surfactant phytotoxicity is suppressed by more than 90% within 5 hours of introduction of the gray water to the bioreactor; processing for more than 12 hours degrades more than 99% of the phytotoxin. Vapor Compression Distillation (VCD) is a physical / chemical method for water purification which employees sequential distillation steps to separate water from solids and to volatilize contaminants. The solids from the waste water are concentrated in a brine and the pure product water (70 - 90% of the total waste water volume depending on operating conditions) retains non of the phytotoxic effects. Results of the bioassay were used to guide evaluations of the suitability of recovered gray water following biological and VCD processing for hydroponic lettuce production in controlled environments. Lettuce crops were grown for 28 days with 100% of the input water supplied with recovered water from the biological processor or VCD. When compared with the growth of plants in control hydroponic solution containing pure deionized water, no growth difference could be measured resulting from any of the recovered water treatments. Both biological treatment and VCD offer alternative technology approaches to recovering water from waste streams appropriate for input into a crop production system. A high level of crop performance (food, air, and water production) can be maintained with either processor; selection decisions can be based on other factors regarding system integration.

Bubenheim, David L.↗

Excess nutrients in hydroponic solutions alter nutrient content of rice, wheat, and potato

Environment has significant effects on the nutrient content of field-grown crop plants. Little is known, however, about compositional changes caused by controlled environments in which plants receive only artificial radiation and soilless, hydroponic culture. This knowledge is essential for developing a safe, nutritious diet in a Controlled Ecological Life-Support System (CELSS). Three crops that are candidates for inclusion in a CELSS (rice, wheat, and white potato) were grown both in the field and in controlled environments where the hydroponic nutrient solution, photosynthetic photon flux (PPF), and CO2 level were manipulated to achieve rapid growth rates. Plants were harvested at maturity, separated into discrete parts, and dried prior to analysis. Plant materials were analyzed for proximate composition (protein, fat, ash, and carbohydrate), total nitrogen (N), nitrate, minerals, and amino-acid composition. The effect of environment on nutrient content varied by crop and plant part. Total N and nonprotein N (NPN) contents of plant biomass generally increased under controlled-environment conditions compared to field conditions, especially for leafy plant parts and roots. Nitrate levels were increased in hydroponically-grown vegetative tissues, but nitrate was excluded from grains and tubers. Mineral content changes in plant tissue included increased phosphorus and decreased levels of certain micronutrient elements under controlled-environment conditions. These findings suggest that cultivar selection, genetic manipulation, and environmental control could be important to obtain highly nutritious biomass in a CELSS.

NASA Discipline Number 61-20↗

Biomass production and nitrogen dynamics in an integrated aquaculture/agriculture system

A combined aquaculture/agriculture system that brings together the three major components of a Controlled Ecological Life Support System (CELSS) - biomass production, biomass processing, and waste recycling - was developed to evaluate ecological processes and hardware requirements necessary to assess the feasibility of and define design criteria for integration into the Kennedy Space Center (KSC) Breadboard Project. The system consists of a 1 square meter plant growth area, a 500 liter fish culture tank, and computerized monitoring and control hardware. Nutrients in the hydrophonic solution were derived from fish metabolites and fish food leachate. In five months of continuous operation, 27.0 kg of lettuce tops, 39.9 kg of roots and biofilm, and 6.6 kg of fish (wet weights) were produced with 12.7 kg of fish food input. Based on dry weights, a biomass conversion index of 0.52 was achieved. A nitrogen budget was derived to determine partitioning of nitrogen within various compartments of the system. Accumulating nitrogen in the hypoponic solution indicated a need to enlarge the plant growth area, potentially increasing the biomass production and improving the biomass conversion index.

Owens, L. P.↗

Cloning crops in a CELSS via tissue culture: Prospects and problems

Micropropagation is currently used to clone fruits, nuts, and vegetables and involves controlling the outgrowth in vitro of basal, axillary, or adventitious buds. Following clonal multiplication, shoots are divided and rooted. This process has greatly reduced space and energy requirements in greenhouses and field nurseries and has increased multiplication rates by greater than 20 fold for some vegetatively propagated crops and breeding lines. Cereal and legume crops can also be cloned by tissue culture through somatic embryogenesis. Somatic embryos can be used to produce 'synthetic seed', which can tolerate desiccation and germinate upon rehydration. Synthetic seed of hybrid wheat, rice, soybean and other crops could be produced in a controlled ecological life support system. Thus, yield advantages of hybreds over inbreds (10 to 20 percent) could be exploited without having to provide additional facilities and energy for parental-line and hybrid seed nurseries.

Carman, John G.↗

Biocompatibility of sweetpotato and peanut in a hydroponic system

'Georgia Red' peanut (Arachis hypogaea L.) and TU-82-155 sweetpotato [Ipomoea batatas (L.) Lam] were grown in monocultured or intercropped recirculating hydroponic systems in a greenhouse using the nutrient film technique (NFT). The objective was to determine whether growth and subsequent yield would be affected by intercropping. Treatments were sweetpotato monoculture (SP), peanut monoculture (PN), and sweetpotato and peanut grown in separate NFT channels but sharing a common nutrient solution (SP-PN). Greenhouse conditions ranged from 24 to 33 degrees C, 60% to 90% relative humidity (RH), and photosynthetic photon flux (PPF) of 200 to 1700 micromoles m-2 s-1. Sweetpotato cuttings (15 cm long) and 14-day-old seedlings of peanuts were planted into growth channels (0.15 x 0.15 x 1.2 m). Plants were spaced 25 cm apart within and 25 cm apart between growing channels. A modified half-Hoagland solution with a 1 N: 2.4 K ratio was used. Solution pH was maintained between 5.5 and 6.0 for treatments involving SP and 6.4 and 6.7 for PN. Electrical conductivity (EC) ranged between 1100 and 1200 microS cm-1. The number of storage roots per sweetpotato plant was similar for both SP and SP-PN. Storage root fresh and dry mass were 29% and 36% greater, respectively, for plants in the SP-PN treatment than for plants in the SP treatment. The percent dry mass of the storage roots, dry mass of fibrous and pencil roots, and the length-to-diameter ratio of storage roots were similar for SP and SP-PN sweetpotato plants. Likewise, foliage fresh and dry mass and harvest index were not significantly influenced by treatment. Total dry mass was 37% greater for PN than for SP-PN peanut plants, and pod dry mass was 82% higher. Mature and total seed dry mass and fibrous root dry mass were significantly greater for PN than for SP-PN plants. Harvest index (HI) was similar for both treatments. Root length tended to be lower for seedlings grown in the nutrient solution from the SP-PN treatment.

Non-NASA Center↗

Nutrient management effects on sweetpotato genotypes under controlled environment

Sweetpotato is one of several crops recommended by National Aeronautics and Space Administration (NASA) for bioregenerative life support studies. One of the objectives of the Tuskegee University NASA Center is to optimize growth conditions for adaptability of sweetpotatoes for closed bioregenerative systems. The role of nutrient solution management as it impacts yield has been one of the major thrusts in these studies. Nutrient solution management protocol currently used consists of a modified half Hoagland solution that is changed at 14-day intervals. Reservoirs are refilled with deionized water if the volume of the nutrient solution was reduced to 8 liters or less before the time of solution change. There is the need to recycle and replenish nutrient solution during crop growth, rather than discard at 14 day intervals as previously done, in order to reduce waste. Experiments were conducted in an environmental growth room to examine the effects of container size on the growth of several sweetpotato genotypes grown under a nutrient replenishment protocol. Plants were grown from vine cuttings of 15cm length and were planted in 0.15 x 0.15 x 1.2m growth channels using a closed nutrient film technique system. Nutrient was supplied in a modified half strength Hoagland's solution with a 1:2.4 N:K ratio. Nutrient replenishment protocol consisted of daily water replenishment to a constant volume of 30.4 liters in the small containers and 273.6 liters in the large container. Nutrients were replenished as needed when the EC of the nutrient solution fell below 1200 mhos/cm. The experimental design used was a split-plot with the main plot being container size and genotypes as the subplot. Nine sweetpotato genotypes were evaluated. Results showed no effect of nutrient solution container size on storage root yield, foliage fresh and dry mass, leaf area or vine length. However, plants grown using the large nutrient solution container accumulated more storage root dry mass than those with the small containers. Although plants grown with the smaller containers showed greater water uptake, plant nutrient uptake was lower than with the larger container. All genotypes evaluated showed variation in their responses to all parameters measured.

Solanaceae/genetics/growth & development↗

Pythium invasion of plant-based life support systems: biological control and sources

Invasion of plant-based life support systems by plant pathogens could cause plant disease and disruption of life support capability. Root rot caused by the fungus, Pythium, was observed during tests of prototype plant growth systems containing wheat at the Kennedy Space Center (KSC). We conducted experiments to determine if the presence of complex microbial communities in the plant root zone (rhizosphere) resisted invasion by the Pythium species isolated from the wheat root. Rhizosphere inocula of different complexity (as assayed by community-level physiological profile: CLPP) were developed using a dilution/extinction approach, followed by growth in hydroponic rhizosphere. Pythium growth on wheat roots and concomitant decreases in plant growth were inversely related to the complexity of the inocula during 20-day experiments in static hydroponic systems. Pythium was found on the seeds of several different wheat cultivars used in controlled environmental studies, but it is unclear if the seed-borne fungal strain(s) were identical to the pathogenic strain recovered from the KSC studies. Attempts to control pathogens and their effects in hydroponic life support systems should include early inoculation with complex microbial communities, which is consistent with ecological theory.

NASA Discipline Life Support Systems↗

Fisher's Peak Ecological Forecasting: Mapping Biomass to Inform Conservation Planning of a Future State Park in Southern Colorado

Fisher’s Peak is a 77.5 km2 property southeast of Trinidad, Colorado that is planned to become Colorado’s newest state park. The area has experienced limited anthropogenic disturbance and is home to an abundance of unique habitats and species. A rapid, approximately 900 m change in elevation over the extent of the area nurtures a variety of plants and animals, including the endangered New Mexico meadow jumping mouse. In 2019, the State of Colorado obtained Fisher’s Peak with plans to make it Colorado’s second largest state park. A diverse group of collaborators, including the Colorado State Forest Service and The Nature Conservancy, worked closely to design the state park to maximize recreation opportunity while conserving the property’s rich habitats and biodiversity. The Fisher’s Peak Ecological Forecasting Team utilized Light Detection and Ranging (LiDAR) surveys, in situ forest inventory data, and Earth observations from Landsat8 Operational Land Imager (OLI), Sentinel-1 C-band Synthetic Aperture Radar (C-SAR), Sentinel-2 Multispectral Instrument (MSI), Advanced Land Observing Satellite 2 (ALOS-2) Phased Array type L-band Synthetic Aperture Radar (PALSAR-2) and the Shuttle Radar Topography Mission (SRTM) to quantify and map biomass over the extent of the study area. The results from modeling biomass had an out-of-bag root mean square error of 55 Mg/ha and an R2 of 12. The resulting map indicates areas where carbon storage on the property is high, informing decision-making processes for future park development. While more in situ training data may improve modeling capacity for biomass in the Fisher’s Peak area, this work represents a feasible attempt to better understand biomass distribution using earth observation.

DEVELOP Tech Paper↗

Fisher's Peak Ecological Forecasting - Mapping Biomass to Inform Conservation Planning of a Future State Park in Southern Colorado

Fisher’s Peak is a 77.5 km2 property southeast of Trinidad, Colorado that is planned to become Colorado’s newest state park. The area has experienced limited anthropogenic disturbance and is home to an abundance of unique habitats and species. A rapid, approximately 900 m change in elevation over the extent of the area nurtures a variety of plants and animals, including the endangered New Mexico meadow jumping mouse. In 2019, the State of Colorado obtained Fisher’s Peak with plans to make it Colorado’s second largest state park. A diverse group of collaborators, including the Colorado State Forest Service and The Nature Conservancy, worked closely to design the state park to maximize recreation opportunity while conserving the property’s rich habitats and biodiversity. The Fisher’s Peak Ecological Forecasting Team utilized Light Detection and Ranging (LiDAR) surveys, in situ forest inventory data, and Earth observations from Landsat 8 Operational Land Imager (OLI), Sentinel-1 C-band Synthetic Aperture Radar (C-SAR), Sentinel-2 Multispectral Instrument (MSI), Advanced Land Observing Satellite 2 (ALOS-2) Phased Array type L-band Synthetic Aperture Radar (PALSAR-2) and the Shuttle Radar Topography Mission (SRTM) to quantify and map biomass over the extent of the study area. The results from modeling biomass had an out-of-bag root mean square error of 55 Mg/ha and an R2 of 12. The resulting map indicates areas where carbon storage on the property is high, informing decision-making processes for future park development. While more in situ training data may improve modeling capacity for biomass in the Fisher’s Peak area, this work represents a feasible attempt to better understand biomass distribution using earth observation

Lauren Lad↗

A summary of porous tube plant nutrient delivery system investigations from 1985 to 1991

The Controlled Ecological Life Support System (CELSS) Program is a research effort to evaluate biological processes at a one person scale to provide air, water, and food for humans in closed environments for space habitation. This program focuses currently on the use of conventional crop plants and the use of hydroponic systems to grow them. Because conventional hydroponic systems are dependent on gravity to conduct solution flow, they cannot be used in the microgravity of space. Thus, there is a need for a system that will deliver water and nutrients to plant roots under microgravity conditions. The Plant Space Biology Program is interested in investigating the effect that the space environment has on the growth and development of plants. Thus, there is also a need to have a standard nutrient delivery method for growing plants in space for research into plant responses to microgravity. The Porous Tube Plant Nutrient Delivery System (PTPNDS) utilizes a hydrophilic, microporous material to control water and nutrient delivery to plant roots. It has been designed and analyzed to support plant growth independent of gravity and plans are progressing to test it in microgravity. It has been used successfully to grow food crops to maturity in an earth-bound laboratory. This document includes a bibliography and summary reports from the growth trials performed utilizing the PTPNDS.

Dreschel, T. W.↗