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The Use of Models to Predict Potential Contamination Aboard Orbital Vehicles

Center for Great Lakes Studies and Department of Biological Sciences, University of Wisconsin-Milwaukee-Martin E. Boraas, Dianne B. Seale
Published 1989-07-01 by SAE International in United States
Biological contamination is a real, perhaps inevitable, event aboard inhabited orbital vehicles. A major form of this contamination is fungal growth on exposed surfaces. While numerous models exist for microbial growth on air-water and surface-water interfaces, no models are available for fungal growth on air-solid surfaces and, evidently, none have been developed for a surface that is non-nutritive, e.g. a surface that not agar or a food stuff. We develop and present a model of fungal growth on air-exposed, non-nutritive solid surfaces. A unique feature of this testable model is that the development of a fungal mycelium can facilitate its own growth by condensation of water vapor from its environment directly onto fungal hyphae. The fungal growth rate is limited by the rate of supply of volatile nutrients and fungal biomass is limited by either the supply of non-volatile nutrients or by metabolic loss processes.
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Radiological Health Risks

NASA Johnson Space Center Houston, TX-D. Stuart Nachtwey
Published 1989-07-01 by SAE International in United States
The crew of a manned Mars mission will be unavoidably exposed to galactic cosmic ray (GCR) flux. If one employs conventional radiological health practices involving absorbed dose(D), dose-equivalents (H), and LET-depen-dent quality factors (Q)2, the Mars mission crew shielded by 2 g/cm All could receive about 0.7 Sv in a 460-day mission at solar minimum. However three-fourths of this dose-equivalent in free space is contributed by high LET heavy ions (Z ≥ 3) and target fragments with average Q of 10.3 and 20, respectively. Such high quality factors for these particles may be inappropriate. Moreover, in a 460-day mission less than half of the nuclei in the body of an astronaut will have been traversed by a single heavy particle. The entire concept of D/Q/H as applied to GCR must be reconsidered.
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High-Temperature Bootstrap Compared with F15 Growth Air Cycle Air Conditioning System

Allied-Signal Aerospace Company AiResearch Los Angeles Division-D. Matullch
Published 1989-07-01 by SAE International in United States
Cooling capacity of the F-15 environmental control system (ECS) has been significantly increased in the current F-15 growth system by applying the high-pressure water separation (HPWS) technique. To further increase the F-15 ECS thermal cycle efficiency, an advanced high-temperature, turbine-powered bootstrap air cycle system has been designed to operate directly from the engine bleed air source. The advanced system more fully exploits the engine compressor bleed air energy potential by using the bleed air at maximum pressure and temperature to drive a power turbine. The power turbine pre cools the bleed air and drives a closed-loop bootstrap air cycle cooling system.The advanced system significantly reduces aircraft fuel consumption because it requires less bleed air and ram air. Furthermore, because it has fewer parts, the projected system reliability is increased and weight is reduced.The paper introduces the subject through a brief discussion of the recent air cycle system approaches and engine bleed air preconditioning techniques. Thermal cycle diagrams compare the advanced high-temperature, turbine-powered bootstrap with the F-15 growth system at extreme operating conditions.
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A Fuel Cell Energy Storage System Concept for the Space Station Freedom Extravehicular Mobility Unit

Ergenics Power Systems, Inc.-Otto J. Adlhart, Matthew J. Rosso
NASA Lyndon B. Johnson Space Center-Jose Marmolejo
Published 1989-07-01 by SAE International in United States
The paper gives an update on an advanced development effort carried out under NASA Johnson Space Center (NASA/JSC) NAS 9-17775 by Ergenics Power Systems, Inc. (EPSI). The work was initiated in April 1987 to design and build a Fuel Cell Energy Storage System (FCESS) bench-test unit for the Space Station Freedom Extravehicular Mobility Unit (EMU). Fueled by oxygen and hydride stored hydrogen, the FCESS is being considered as an alternative to the EMU zinc-silver oxide battery. Superior cycle life and quick recharge are its main attributes. Design and performance of a non-venting 28V, 34 Ahr system with 7 amp rating are discussed. The FCESS is comprised of a 32-cell proton exchange membrane (PEM) stack, a metal hydride storage vessel and a control subsystem. The stack design incorporates passive product-water removal and thermal integration with the hydride vessel. The hydride vessel stores enough fuel for 5 hours. The control subsystem provides reactant pressure and flow regulation, automatic startup, shutdown and electronic protection against malfunctioning
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Detection of Extravehicular Activity Generated Contamination

Perkin-Elmer Corporation, Applied Science Division, Pomona, GA-Richard A. Heppner
Published 1989-07-01 by SAE International in United States
Extravehicular activity (EVA) for maintenance purposes exposes the astronaut and associated gear to toxic substances such as hydrazine and ammonia. Adsorption of these compounds on surfaces of the EVA gear allows them to be carried into the S.S, Freedom atmosphere when the astronaut clears the airlock. A quadrupole based mass analyzer system is proposed for use as an External Contaminant Monitor (ECM) to monitor these and other compounds. The unit occupies approximately 0.5 cu ft, requires 16 W of power, and weighs 22 pounds. It can pinpoint contamination sources with high sensitivity, identifying both known target and also unknown, “stranger,” compounds.
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A Modeling System for Control of the Thermal and Fluid Dynamics of the NASA CELSS Crop Growth Research Chamber

Department of Mechanical EngineeringThe University, of Texas at Arlington-Ann L. Blackwell, C. C. Blackwell
Published 1989-07-01 by SAE International in United States
The Crop Growth Research Chamber (CGRC), which is being developed under the Controlled Ecological Life Support System program at NASA Ames Research Center, will be operated to support research on the growth dynamics of crops of higher plants within a closed, precisely controlled environment. The CGRC is the first in a series of instruments which will be incorporated into bioregenerative life support systems for space habitats. The dynamic processes of the thermal and fluid portions of the CGRC are profoundly coupled with those of the plants and there is strong reason to believe that consideration of these interactions is necessary in order to design a CGRC which will support sound research.In this paper we describe the modeling system which we have developed for the thermal and fluid dynamics of the CGRC. The bases of the modeling system are symbolic representations of the individual processes which are included in the representation. The system includes the plant growth chamber, the associated control system components and the control devices. An example of the derivation of the dynamic equations…
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Preliminary Design of JEM Environmental Control and Life Support System

Kawasaki Heavy Industries, Ltd. (KHI)-A. Hattori, H. Hama
National Space Development Agency of Japan (NASDA)-K. Shiraki, H. Hashimoto, K. Manabe
Published 1989-07-01 by SAE International in United States
This paper outlines the current status of the preliminary design study of the Japanese Experimental Module (JEM) Environmental Control and Life Support System (ECLSS), one of the subsystems in JEM which is attached to the Space Station core.ECLSS functions to be provided are defined and identified based on the system requirements levied on JEM ECLSS.The design concepts for ECLSS function allocation between JEM and the SS core, and JEM ECLSS function/hardware distribution are also established.In addition, the issues and concerns related to the ECLSS interface between the SS core and JEM are introduced.The design approach emphasizes the JEM emergency system concept with respect to contamination control and monitoring and to fire detection and suppression, which must be standardized throughout all modules in SS.
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Intelligent Fault Tolerant Systems for Thermal Control in Space Applications

Microtecnica Torino - Italy-P. Osella
Published 1989-07-01 by SAE International in United States
This paper describes two smart fault tolerant systems (EURECA TCU and Pump Package ECU) that have been studied by MICROTECNICA in the frame of European Space programs.EURECA TCU: The TCU is the electronic unit of the FURECA Thermal Control System and consists of two cold redundant sections each with the prime task of controlling the temperature of 129 points on the carrier. It does this by switching on and off the appropriate heater, according to the temperature measured by the dedicated thermistors. Each control loop (thermistor, TCU, heater) is dual redundant and con be in case of one failure. The system can tolerate one failure without the loss of the correspondent control function.PUMP PACKAGE ECU: This is a proposed system to act as the electronic unit for the control and regulation of the mass Flow of a water and/or freon pump package. It consists of two redundant electronic control channels. Each channel is capable of fulfilling the control function autonomously, to diagnose a failure condition and then to self inhibit. Therefore, the combination of the…
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Artificial Intelligence Application to Advanced ECLS Systems

Benjamin E. Bishop, Albert M. Boehm
Published 1989-07-01 by SAE International in United States
Space Station preliminary design studies examined the role of advanced automation and artificial intelligence to facilitate ECLSS control and diagnostics. Advanced automation techniques using independent embedded controllers were selected for the initial station, especially for centralized processes such as water recovery, air revitalization, and waste management. This paper examines the role that advanced computer capabilities can play to enhance advanced missions such as growth station, Moon and Mars exploration. The benefits of artificial intelligence are presented from both the expert system and learned system perspective.
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PRELIMINARY G189A COMPUTER PROGRAM MODELING OF THE SPACE STATION ECLSS

Boeing Aerospace, Huntsville, Alabama-Robert S. Barker, Roger von Jouanne
Published 1989-07-01 by SAE International in United States
The initial development and subsequent evolution of the Environmental Control and Life Support System (ECLSS) for the manned Space Station requires a numerical modeling computer program that can accurately simulate the ECLSS.The G189 program has successfully provided this modeling function for the Skylab refrigeration system and for the Environmental Control System (ECS) in the Space Shuttle Orbiter. Presently being developed at Boeing Aerospace is an overall Space Station ECLSS model, which is being constructed and operated at increasing levels of complexity.This paper presents and discusses the Boeing G189A model of the baseline Space Station ECLSS. The model is in an early stage of refinement and includes all ECLSS functional operations except Fire Detection and Suppression (FDS) (which is in the detection mode only during normal Station operation) and the Avionics Air Cooling/Heating portion of the Temperature and Humidity Control (THC) Subsystem. At the present level of development, the model is used primarily to obtain detailed fluid-interface mass flows and other mass-balance information, while thermal exchange and interrelationships are very simplified.
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