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This paper outlines the current status of the Space Station Environmental Control and Life Support System (ECLSS). The seven subsystem groups which comprise the ECLSS are identified and their functional descriptions are provided. The impact that the nominal and safe haven operating requirements have on the physical distribution, sizing, and number of ECLSS subsystems is described. The role that the major ECLSS interfaces with other Space Station systems and elements play in the ECLSS design is described.

The use of thermodynamic power cycles in space results in much higher conversion efficiencies than the traditional solar cell or thermoelectric couple. This has many beneficial consequences in both solar and nuclear applications. The 20% to 30% cycle efficiency reduces the solar energy collection area significantly, thereby reducing size, weight and drag for low earth orbit missions such as the Space Station. For nuclear fueled systems, the 4 to 5 fold increase in conversion efficiency over thermoelectrics reduces the amount of fuel needed, thereby reducing weight, size, cost and hazard. Two competing dynamic cycles, the Organic Rankine Cycle (ORC) and the Closed Bray ton Cycle (CBC), are being developed by NASA LeRC for solar dynamic systems on the Space Station and by DOE for the U.S. Air Force. For each application (solar or nuclear), the basic cycles are similar. The major variable is power level. The solar dynamic systems being considered are in the 20 to 40 KWe range.

For long term manned space missions, considerable quantities of materials for life support will be consumed. The ability to recycle such materials, particularly water, offers significant benefits in reducing the costs and logistical difficulties of resupply from earth. The application of supercritical water oxidation (SCWO) waste treatment and water recycling technology to the problem of waste disposal in space is being developed for NASA by MODAR, Inc. As inorganic constituents present in the waste are not soluble in supercritical water, they must be removed from the organic-free, supercritical fluid reactor effluent. Experimental results are presented on the separation of solids from the process stream by removal mechanisms which could be suitable for a microgravity environment. The solid properties and their influence on the design of several oxidation reactor/solids separator configurations under study are presented.

Future large spacecraft such as the Space Station will have high power dissipations and long heat transport distances. The combination of these two requirements dictate the need for a new heat transport technology. Boeing Aerospace developed an ammonia thermal bus (ATB) concept using two-phase ammonia as the working fluid. Instrumentation and control systems were used to verify system performance, protect personnel and equipment safety, and run the system. The ATB was robust; thus operating procedures were simple and fault tolerant. Test results demonstrated a maximum heat load of 22 kW, a controllable turndown ratio of 44:1, and the ability to control setpoint temperatures within the range of 30 to 90°F. This paper describes the ammonia thermal bus (ATB), test instrumentation and control, procedures for operating the ATB, and test results.

Future long term space flights will require on-board water/waste recycling in a partially or fully enclosed life support system. Oxidation of the products of human metabolism in supercritical water has been shown to be an efficient way to accomplish this recycling. Fundamental understanding of the oxidation of compounds in supercritical water is essential for the design, development and operation of a supercritical water oxidation unit. Oxidation studies of methane up to 700°C have recently been completed and are presented in this paper. Experiments are currently being performed to determine reaction kinetic parameters for the oxidation of other model compounds in supercritical water such as ammonia, methanol, acetaldehyde, and mixtures of ammonia and co-oxidants. Theoretical studies of fundamental kinetics and mechanistic pathways in supercritical water oxidation are discussed.

Due to the need to reduce the power requirements and thus the weight of large space-based neutral particle beam (NPB) space platforms, current systems studies propose that these NPB accelerators be maintained at cryogenic temperature levels. As such, the ground test articles that will be used to develop many of the technological advancements necessary prior to engineering development of an operational NPB space platform, will also address the issues of operating cryogenically. In support of a number of these programs, a cryogenic cooling test of a typical accelerator component was performed. This paper discusses the various modes of cryogenic cooling proposed (two-phase convective boiling and single-phase supercritical convection), the advantages and disadvantages of each, gives details of the test, and compares the test results to analytical predictions.

Space Station nodes packaging analyses are presented relative to moving environmental control and life support system (ECLSS) equipment from the habitability (HAB) module to node 4 in order to provide more living space and privacy for the crew, remove inherently noisy equipment from the crew quarter, retain crew waste collection and processing equipment in one location, and keep objectionable odor away from the living quarters. In addition, options for moving external electronic equipment from the Space Station truss to pressurized node 3 were evaluated in order to reduce the crew extravehicular activity (EVA) time required to install and maintain the equipment. Node size considered in this analysis is 3.66 m (12 ft) in diameter and 5.38 m (17.67 ft) long. The analysis shows that significant external electronic equipment could be relocated from the Space Station truss structure to node 3 and non-life critical ECLSS HAB module equipment could be moved to node 4.

Thermal climate in automobiles, buses, trucks arid indoors has been evaluated using a newly developed thermal manikin. Heatman. Test results indicate a noticeable difference among cars. In a cold environment, the general problem is distribution between wind screen and lower part and asymmetry for right and left sides of individuals. In a warm climate, air is often distributed unevenly, thus resulting in discomfort. The results are shown as heat flow (W/m2) from 36 areas of the body or as equivalent (sensed) temperatures. The PMV-PPD comfort index is also derived from these measurements. Measurement and assessment of thermal climate using a thermal manikin will make it possible to evaluate the best solution for thermal control. It can also be used to measure clothing and chair insulation.

This paper describes the development of a membrane-based dehumidification process for space-based applications, such as spacecraft cabins and extra-vehicular-activity (EVA) space suits. Results presented are from 1) screening tests conducted to determine the efficacy of various membranes to separate water vapor from air, and 2) parametric and long-term tests of membranes operated at conditions that simulate the range of environmental conditions (e.g., temperature and relative humidity [RH]) expected in the planned space station. Also included in this paper is a discussion of preliminary designs of membrane-based dehumidification processes for the space station and EVA space suits. These designs result in compact and energy-efficient systems that offer significant advantages over conventional dehumidification processes.

One of the most closely related system to the life of crew in a manned spacecraft is the Environment Control and Life Support System. ECLSS includes such functions as temperature control, humidity control, pressure control, air circulation, carbon dioxide removal and concentration, carbon dioxide reduction and oxygen generation, and contamination control. The first Japanese space habitable system called JEM (Japanese Experimental Module) will be operated by being attached to the U.S. Space Station. Several functions such as CO2 and trace contaminant control are considered in JEM. while others are dependent on the U.S. module. (1)* It is necessary to expand ECLS functions for the future Japanese peculiar space station. Solid Amine water desorbed carbon dioxide removal and concetration test bed using heat recovery provision for the energy saving operation has been successfully tested with more than 99% of carbon dioxide concentration purity.

The Space Station provides a unique facility for conducting material processing and life science experiments under microgravity conditions. These conditions place special requirements on the U.S. Laboratory for storing and transporting chemicals and process fluids, reclaiming water from selected experiments, treating and storing experiment wastes, and providing vacuum utilities. To meet these needs and provide a safe laboratory environment, the Process Material Management System (PMMS) is being developed. Preliminary design requirements and concepts related to the PMMS are addressed in addition to discussing the MSFC PMMS breadboard test facility and a preliminary plan for validating the overall system design. The system contains a fluid handling subsystem which manages process fluids required by each experiment while a chemical storage facility safely stores potentially hazardous chemicals.

ILC Dover, Inc. under contract to the United States Air Force Human Systems Division (AFSC) has developed a prototype laboratory test garment known as the “Advanced High Altitude Flight Suit” (AHAFS). The suit incorporates technologies first developed for NASA with the Apollo and Shuttle programs, but optimized in their present iteration for long term uninflated wear (as emergency decompression protection) in pressurized aircraft cockpits. The program has additionally attempted to achieve better mobility in the pressurized state by defining and systematically addressing a specified mobility envelope. Related construction techniques employ single and double axis “soft” joints, which can be engineered to permit full access to existing or contemplated cockpit designs. Proper balancing of wall tensions across these joints has resulted in lower suit loads, increased mobility, and established the feasibility of a higher suit operating pressure (5 psi).

Tests were conducted to compare the thermal performance of five types of wafer thin coolers; a double pass microchannel cooler, two types of single pass microchannel coolers, and two versions of an impingement cooler. The primary application of these devices is to remove heat from compact gallium arsenide diode wafers used in laser communications, but they can also be applied to a variety of other applications ranging from high density electronic packaging to hypersonic surfaces. The coolers were designed to absorb heat fluxes of over 100 W/cm2 with minimal surface temperature gradients. The coolers had a heat input area of 1 cm2, used water as the cooling fluid and had thicknesses ranging from 1 to 1.8 mm. One single pass microchannel cooler was made of beryllium oxide. The other four coolers were made of copper. A. special heat flux amplifier was built to obtain the high heat flux values with conventional heaters, and to provide instrumentation to determine temperature gradients.

NASA's Office of Exploration currently is studying a range of initiative options that would extend the sphere of human activity in space to Mars, and includes permanent bases or outposts on the Moon and Mars. These missions are challenging in many technology areas, not the least of which is life support, where the requirements for long term, remote operations, with long supply lines, place major demands on life support systems for safety, reliability and performance. The scenarios being developed by the Office of Exploration will serve as guides to the selection of a new exploration initiative for NASA. In the current phase of the process, it is important to explore some of the critical elements, such as the advanced life support area, to determine whether the proposed missions can be accomodated with current knowledge, or whether additional technological advances are necessary.

The regenerate two-bed carbon dioxide removal system, utilizing carbon molecular sieve (CMS), represents a significant advancement over the current Space Station four-bed zeolite molecular sieve baseline system. To demonstrate the feasibility of the CMS system approach. AiResearch conducted system performance tests on a two-bed system created by modifying the existing flight qualified Skylab regenerable carbon dioxide removal system. Results of the performance tests confirmed the two-bed CMS system approach as a viable candidate for Space Station regenerable carbon dioxide removal.

Long-term manned operation of the National Aeronautics and Space Administration's (NASA's) Space Station will require the use of regenerative processes for the revitalization of the Spacecraft atmosphere. Life Systems, Inc. (Life Systems), in conjunction with NASA's effort to mature water electrolysis technology for applications in the Space Station Environmental Control and Life Support System (ECLSS), is developing an alkaline-based Oxygen Generation Assembly (OGA) which utilizes the Static Feed Electrolyzer (SFE) concept. The OGA is required on the Space Station to provide metabolic oxygen (O2) for the crew, compensate for O2 lost overboard due to Space Station leakage, supply O2 for airlock repressurization and provide hydrogen (H2) for the reduction of carbon dioxide (CO2).

Strategic planning for human space exploration early in the 21st century has addressed two major missions - a lunar outpost/base and a piloted Mars mission. Such missions into the space environment, lasting perhaps 1–3 years, will impose unprecedented conditions on providing for human sustenance, well-being, and performance. The conditions may be categorized as: significantly increased time away from earth, unaccustomed risk and environmental stress, and an unrelieved, total dependence on advanced technological systems. A program approach, embodied in the Humans-in-Space thrust of the proposed Project Pathfinder, is described that would determine the critical human and technology requirements and develop the enabling technologies for human self-sufficiency and productivity on these missions.

Airlines and Airports are pace setters in the introduction and use of new technology. An example is the Visual Display Unit, its potential being steadily developed to make use of computer held data and applied to a growing number of applications in the race for improved performance. The VDU displays the computer produced related information accurately and quickly. Used effectively it speeds and smooths the flow of passengers through the airport.

Automated cargo systems are becoming more complex as greater volumes of air freight must be handled in less time with lower costs. The risk associated with implementing these systems is demanding that more sophisticated techniques be exploited in their design. Computer simulation affords a means of prototyping a design in software before configuration commitments must be made. This paper provides an introduction to simulation and the major pitfalls to be avoided. The application of simulation to an actual air cargo system is discussed along with the use of computer graphics to animate system behavior.