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The CELSS Antarctic Analog Project (CAAP) is a joint NSF and NASA project tor the development, deployment and operation of CELSS technologies at the Amundsen-Scott South Pole Station. CAAP is implemented through the joint NSF/NASA Antarctic Space Analog Program (ASAP), initiated to support the pursuit of future NASA missions and to promote the transfer of space technologies to the NSF. As a joint endeavor, the CAAP represents an example of a working dual agency cooperative project. NASA goals are operational testing of CELSS technologies and the conduct of scientific study to facilitate technology selection, system design and methods development required for the operation of a CELSS. Although not fully closed, food production, water purification, and waste recycle and reduction provided by CAAP will improve the quality of life for the South Pole inhabitants, reduce logistics dependence, and minimize environmental impacts associated with human presence on the polar plateau.

The results of an airflow distribution study based on a one-dimensional flow model are presented. The object of study was to characterize the distribution of the airflow emerging from the floor of a crop growth chamber of the type which is relevant in the development of a closed ecological life support system.

Planetary surface exploration involves a variety of tasks whose accomplishment demands a broad mix of capabilities and strategies. As a model for the general problem, the exploration of Earth and the first forays to the Moon can be used to illustrate some of the strategies that have been used up to the present. Future exploration of the solar system can be guided by lessons learned in our own planetary system, and the use of hazardous environments on Earth can provide a valuable testing ground for future approaches to exploration. Some lessons from past Antarctic expeditions and recent field results from the Antarctic Space Analog Program illustrate the use of analog environments in preparation for space exploration.

A closed-loop, regenerative life support system must include a method for recycling organic waste materials. With a Controlled Ecological Life Support System (CELSS), this will be accomplished by decomposing the wastes and using the effluent to formulate a nutrient solution which supports food production by plants. The waste processing technology used may be either physicochemical or biological. Although the effluents from biological processors have been extensively evaluated as fertilizers for soil-based agricultural systems, few experiments have been conducted to evaluate their suitability in hydroponic applications. This paper describes the results of a series of experiments performed to evaluate effluent from an anaerobic bacterial reactor as a nutrient source for hydroponically-grown plants. Germination and initial seedling growth were found to be suppressed by pure effluent.

The front half of the nitrogen fixation system, which is one of the subsystems of Controlled Ecological Life Support System (CELSS), or NH3 synthesis loop at atmospheric pressure, was studied. The NH3 separation essential in the loop is discussed. The NH3-PSA method was newly developed, since the NH3-PSA was evaluated best among separation methods from the viewpoints of CELSS criteria. It is essential to retain the H2/N2 ratio in the outlet gas the same as that of the inlet gas to the PSA. From the experimental result of PSA a material balance of the NH3 synthesis loop was calculated. Additionally a material balance of the overall process was calculated by assuming some performances in the down stream sections of the NH3 synthesis loop.

Inedible plant materials are a valuable resource in a controlled ecological life support system (CELSS). These plant “wastes” yield the sugars which facilitate the microbial-based recycle of C, H, O, and N. Conversion of these wastes to carbon dioxide and heat while also generating nutritious foodstuffs requires that: 1) the recalcitrance of cellulose in these materials be understood, and 2) ways be found to efficiently overcome the protective effect of lignin and other components closely associated with the cellulose. Means must be found to cost effectively increase the bioavailability of the cellulose which are intrinsically safe and environmentally compatible. The pretreatment of cellulosic materials in liquid water at temperatures above 200°C can give a hydrated, swollen cellulose. The resulting enhancements in surface area increase the rate of enzyme hydrolysis.

A palladium catalytic oxidizer is being developed to remove plant-generated oxygen from a closed plant growth chamber, replacing the oxygen with carbon dioxide gas and water vapor. The device will provide a relatively simple means of preventing oxygen build-up within the chamber. It may also be used to simulate man-in-the-loop at whatever scale is desired. Discussion is provided on how the device fits in with the development of the closed plant growth environmental chamber in the short term and with controlled ecological life support systems (CELSS) development in the longer term. Alternative means of oxygen removal are compared. The results of preliminary kinetics testing is presented.

The Capillary Pumped Loop Flight Experiment (CAPL) is a prototype of the Earth Observing System (EOS) instrument thermal control systems. Four CAPL flight hardware components were tested in the Instrument Thermal Test Bed at NASA's Goddard Space Flight Center. The components tested were the capillary cold plates, capillary starter pump, heat pipe heat exchangers (HPHXs), and reservoir. The testing verified that all components meet or exceed their individual performance specifications. Consequently, the components have been integrated into the CAPL experiment which will be flown on the Space Shuttle in late 1993.

NASA's Earth Observing System (EOS) Program will place large unmanned polar-orbiting spacecraft in low-earth orbit to support a variety of earth-observation missions. The EOS AM instrument set has two instruments requiring Capillary Pumped Heat Transport Systems (CPHTS) using Capillary Pumped Loop (CPL) technology for thermal accommodation. Significant development testing is required to retire CPHTS design risks early in the EOS program. The first phase of CPHTS development testing has been completed using a modified version of an existing Martin Marietta test bed, the Technology Demonstration Model (TDM). The EOS/TDM testing provided additional proof-of-concept testing for CPL operations and pushed the performance envelope of the TDM system in order to determine the limits of CPL system performance. In addition, the testing provides a database from which analysis methods can be validated. This paper summarizes the EOS/TDM test results.

A Capillary Pumped Loop (CPL) is an advanced two-phase heat transport device which utilizes capillary forces developed within porous wicks to move a working fluid. The advantage this system has over conventional thermal management systems is its ability to transfer large heat loads over long distances at a controlled temperature. Extensive ground testing and two flight experiments have been performed over the past decade which have demonstrated the potential of the CPL as a reliable and versatile thermal control system for space applications. While the performance of CPL's as “black boxes” is now well understood, the internal thermo-fluid dynamics in a CPL are poorly known due to the difficulty of taking internal measurements. In order to visualize transient thermohydraulic processes occurring inside an evaporator, a see-through capillary evaporator was built and tested at NASA's Goddard Space Flight Center.

Exploration of the Moon is the most crucial and decisive step toward human expansion into the vast reaches of space. The Moon is the natural and ideal testbed for determining human capability to survive, function, expand and settle into the space environment. Scientific studies, astronomic observations, and exploitation and utilization of space resources culminating in the establishment of a self-sufficient permanently human-tended lunar base are the goals of lunar exploration. Four development stages in the evolutionary exploration of the Moon are suggested: (1) exploratory; (2) pioneering; (3) outpost; and (4) base. Overall goals and specific objectives, functional requirements, construction conditions, and life support systems requirements needed in each stage are identified.

MMARS (Moon/MArs-base Resource Simulator) is a computer program that automatically generates quantitative summaries of the physical resources (components and facilities) required for normal operation of a planned planetary base or other large project. The user enters a small set of base task descriptors which define the goal or purpose of the base, and the program automatically adds all components, facilities, and functions needed to support that task. And because the support components added also generate a need for support themselves (any component may require power, or labor to operate, for example), MMARS continues, in recursive fashion, to add components and facilities to support the growing list of components and facilities, until the demand for new resources no longer increases.

NASA's Earth Observing System (EOS) Program will place a series of unmanned polar-orbiting spacecraft in low-earth orbit to support a variety of scientific and Earth-observing missions. The EOS AM spacecraft has a requirement for an advanced heat transportation system for thermal energy. A Capillary Pumped Heat Transportation System (CPHTS) using Capillary Pumped Loop (CPL) technology was selected to accommodate the instruments requiring advanced heat transport.

NASA's future missions to explore the solar system will be long-duration missions and could last years at a time. Human life support systems required for these missions must operate with very high reliability for long periods of time and must be highly regenerative, requiring minimum resupply. Such life support systems will make use of combining higher plants, microorganisms, and physicochemical processes to recycle air and water, process wastes, and produce food. Development of regenerative life support systems will be a pivotal capability for missions to the moon and Mars. One key step in the development process for these systems is the establishment of a human-rated test facility specifically tailored for evaluation of closed, regenerative life support systems--one in which long-duration testing can take place involving human test crews.

This paper will overview the system level testing of the Passive Thermal Control System (PTCS) for the Space Station Freedom (SSF) and highlight the design concepts that have evolved from the testing. The specifics of several system level tests, simulations and prototype will be discussed in detail. A series of development tests have been conducted under simulated space environments and operating conditions to verity the PTCS design, which is an essential component in ensuring the survivability of the Space Station Freedom in the hostile space environment for a mission life of 30 years. The Passive Thermal Control System is required to maintain the interior surface temperatures above 60°F (15.6°C) to prevent condensation and below 113°F (45°C) to protect the crew. In addition, the PTCS design must satisfy a thermal temperature range requirement of −250°F to +300°F (−156.7°C to 148.9°C) and a acceptable thermal leak requirement from the pressurized modules.

This study examines the lunar environment, the lunar rover mission, and the factors that influence EMU walkback range in the event of a rover failure many kilometers from base. A heuristic method to estimate walkback range of EVA astronauts is presented. An attempt is made to quantify the EVA walkback factors that influence the total walkback range of the lunar EVA astronaut given a fixed duration of the EMU. A walkback range estimate can then be used to carefully structure EVA missions and will help in future designs of EMUs.

The Space Station Freedom program requires long-life thermal control coatings that are stable in low Earth orbit (LEO). To provide designers with a variety of coatings and optical properties, improvements were made to existing coatings, and new thermal control coatings were developed. Anodized aluminum was demonstrated to be an acceptable substrate for inorganic thermal control coatings such as Z-93. Mixtures of Z-93 with stable black oxides provided a wide range of optical properties and were stable in a simulated LEO environment. In addition, sulfuric acid anodized aluminum was developed to a production status to provide controlled optical properties for many aluminum alloys.

Effective emittance was measured for four Multi-Layer Insulation (MLI) blankets designed for Space Station fluid lines. Blanket #2 was built for a 25.4 mm line; Blankets #1, 3 and 4, were built for 12.7 mm lines. Blankets #3 and 4 minimized flap material to reduce heat loss. Blankets #1, 2, and 3 had aluminized inner surfaces; Blanket 4 had a Kapton inner surface. All measured effective emittance values were within 30% of similar Orbiter MLI. Blanket #3 effective emittance values ranged from 0.056 to 0.080 for 47 to -43°C lines, demonstrating improvement from reducing flap material.

The purpose of this paper is to discuss the selection of a low-temperature coolant used to support Space Station Freedom Active Thermal Control System (SSF ATCS) qualification testing. SSF ATCS testing will use liquid nitrogen (LN2) to reduce the temperature of an intermediate coolant to as low as −78°C; the coolant will then interface with the ATCS working fluid to simulate the heat sink conditions of space. Selection of the intermediate coolant required investigation of the following coolant properties: low freezing point, low viscosity at low temperatures, very low to no toxicity and flammability, and low to moderate vapor pressure at room temperature. Of the four refrigerants that were initially considered, R-124 appeared to be the most attractive. A test was performed to verify the freezing point of R-124. The R-124 test results and a comparison of the four refrigerants are described in detail in this paper.

The National Aeronautics and Space Administration (NASA) Space Station Freedom (SSF) will use Flow-Through Radiators (FTRs) to reject waste heat that is collected from the on-board Heat Acquisition Devices (HADs). The waste heat is sent to the FTRs via the Pump Module Assembly (PMA) subsystem of the External Active Thermal Control System (EATCS). Two developmental FTR panels were integrated with the EATCS Ground Test Article (GTA). The integrated components were investigated under a thermal/vacuum environment in Thermal/Vacuum Chamber A at NASA/JSC during June, 1992. A detailed SINDA/FLUINT FTR model was developed to predict the steady-state thermal/hydraulic performance of the FTRs. A simplified SINDA/FLUINT FTR model was also developed for use in the GTA integrated model. Schematics and plots comparing the test data and model results are presented for both steady-state and transient conditions.