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This paper presents the conceptual design of a life support system sustaining a crew of six in a piloted Mars sprint. The requirements and constraints of the system are discussed along with its baseline performance parameters. An integrated operation is achieved with air, water, and waste processing and supplemental food production. The design philosophy includes maximized reliability considerations, regenerative operations, reduced expendables, and fresh harvest capability. The life support system performance will be described with characteristics of the associated physical-chemical subsystems and a greenhouse. MANNED MISSIONS TO THE PLANET MARS are included in the present NASA plans for the first decade of the next century [1]*. The first step of human exploration and eventual settlement on Mars will probably be a series of fast missions (“sprints”), with a duration of just over one year, round trip [2].

The new generation of high-pressure hard space suits allows designers to employ passive means of thermal control of the suit, with a reflective coating. An effort is underway to determine the coating material of choice for the AX-5 prototype hard space suit. Samples of 6061 aluminum have been coated with one of 10 selected metal coatings, and subjected to corrosion, abrasion and thermal testing. Changes in reflectance after exposure are documented. Plated gold exhibited minimal degradation of optical properties. A computer model is used in evaluating coating thermal performance in the EVA environment. The model is verified with an experiment designed to measure the heat transfer characteristics of coated space suit parts in a thermal vacuum chamber. Details of this experiment are presented here.

This paper describes the major lunar resources that would be tapped in developing a Controlled Ecological Life Support System (CELSS) greenhouse for a manned lunar base. The use of the moon's gravitational field, natural sunlight, and mineral resources from the lunar surface are discussed. Lunar soil processing technologies with CELSS relevance, and their contributions to greenhouse development are presented.

The Space Station Extravehicular Activity (EVA) Test Bed program at the Johnson Space Center (JSC) is addressed. A summary of the current testing activities are discussed as well as the test bed goals and future plans to support the Space Station Extravehicular Activity System (EVAS) development program.

Regenerable carbon dioxide (CO2) and moisture removal techniques that reduce expendables and logistics requirements are needed to sustain people undertaking extravehicular activities for the Space Station. Life Systems, working with National Aeronautics and Space Administration has been developing and investigating the ways to advance the Electrochemically Regenerable CO2 and Moisture Absorption (ERCA) technology to replace the nonregenerable solid lithium hydroxide absorber for the advanced Portable Life Support System (PLSS). During extravehicular activities the ERCA technique uses a mechanism involving gas diffusion and absorption into liquid absorbent for the removal and storage of the metabolically produced CO2 and moisture. Following the extravehicular activities, the expended absorbent is regenerated on-board the Space Station by an electrochemical method which restores the CO2 and moisture absorption capabilities of the absorbent.

The Extravehicular Activity (EVA) operations for Space Station (SS) require that a regenerable carbon dioxide (CO2) absorber be developed for the manned Extravehicular Mobility Unit (EMU). A concept which employs a solid amine resin to remove metabolic CCL and water vapor from the breathing air within the space suit is being developed by the Hamilton Standard Division of United Technologies Corporation under Contract NAS 9-17480 with the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC). The solid amine is packed within a water cooled metal foam matrix heat exchanger to remove the exothermic heat of chemical reaction. After completion of the EVA mission, the amine is regenerated on board the Space Station within the heat exchanger using a combination of heat and vacuum. This paper describes the concept design features, operational considerations and test results during simulated laboratory conditions.

This paper outlines the selection, design, and testing of a prototype nonventing regenerable astronaut cooling system for Extravehicular Activity (EVA) space suit applications, for mission durations of four hours or greater. The selected system consists of the following key elements: a radiator assembly which serves as the exterior shell of the portable life support subsystem (PLSS) backpack; a layer of phase change thermal storage material, n-hexadecane paraffin, which acts as a regenerable thermal capacitor; a thermoelectric heat pump; and an automatic temperature control system. The capability for regeneration of thermal storage capacity with and without the aid of electric power is provided.

Future space missions will feature extensive EVA operations. In order to avoid the expendables and logistics penalties associated with recharging the EMU's oxygen supply bottles on the ground, a High Pressure Oxygen Recharge System (HPORS), is being developed for use aboard the Space Station. The HPORS will be an electrolysis system capable of providing oxygen at up to 6000 psia without the use of a mechanical compressor, using only the facilities that will be available on board the Space Station (electrical, nitrogen and water). The Hamilton Standard HPORS will be based on a solid polymer electrolyte system which has already demonstrated thousands of hours of performance at 3000 psia in an oxygen generating plant for military applications. The program includes testing of various water feed modes, operating temperatures and current densities in order to optimize the system size, weight and power consumption.

Performing checkout, servicing, and maintenance of an Extravehicular Activity System (EVAS) on board the Space Station presents several unique challenges. This paper reviews the progress that has been made in the initial effort to define, design, and develop a system that will perform this function. The need for rapid “turnaround” of the EVA capability has not been a significant requirement for the Shuttle program where EVA is only an occasional occurrence (two missions per year). Because of this in frequency and because reservicing is performed on the ground rather than on orbit, the current expenditure of approximately 3,000 manhours to process each Shuttle Extravehicular Mobility Unit (EMU) is acceptable. However, current estimates on the EVA frequency required to support Space Station operations is projected at twice weekly.

The space-erectable radiator system (SERS) is being developed by NASA-JSC to provide a long-life, highly reliable waste heat rejection capability for Space Station and similar large space systems. In general, the SERS features modular, high-capacity radiator panels that can be installed and replaced on-orbit, as needed. Each panel interfaces with the central heat transport loop through a dry contact heat exchanger attachment. The Grumman prototype SERS is based upon a low-risk extension of proven monogroove heat pipe technology for the radiator element and a simple “whiffletree” mechanical clamping mechanism for achieving the required contact pressure at the dry attachment interface. The SERS ground test article that has been built consists of eight radiator panels, each 1 ft wide by 48 ft long, and eight separate whiffletree clamps that engage a 2 ft2 contact area.

The anodic coatings developed by anodizing specific aluminum alloys show considerable promise as long-life/durable radiator coatings. These coatings, formed by the sulfuric acid anodizing process, were the best performers of a variety of candidate coatings subjected to ultraviolet radiation and temperature-cycling tests.

As the Space Station Preliminary Design Review (PDR) and Critical Design Review (CDR) milestones approach, critical technology decisions lie ahead for all major systems to be flown on the vehicle. In the area of thermal management, two-phase heat transport technology has been baselined to meet the Space Station need for transporting large heat loads, providing flexibility to a wide range of potential users, accommodating on-orbit growth, and operating reliably for long life. The thermal test bed (TTB) is an evolutionary program, providing the Space Station program with critical elements of thermal technology development and integrated system performance assessment. Initiated formally in 1984, the TTB has provided confidence in verifying the readiness of two-phase thermal technology for use on the phase I configuration of the Space Station.

The U.S./International Space Station will be assembled incrementally using nineteen flights of the National Space Transportation System (NSTS) Space Shuttle to complete the configuration. This process will produce nineteen different spacecraft configurations, each of which must perform as a fully functional, independent space vehicle. This results in unique design requirements on station distributed systems necessary to allow incremental system buildup while providing some minimum capability early in the assembly sequence. The Thermal Control System (TCS), like electrical power, attitude control, and communications must be present on the initial flight configuration and must grow in capability as assembly continues. This paper summarizes the Space Station program requirements for the TCS, and outlines the capabilities of the TCS for each assembly configuration.

We conducted a study to determine if oxygen toxicity occurs in a proposed extravehicular activity (EVA) pressure suit environment. Twelve male subjects were exposed to 100% oxygen at 9.5 psia for 5 consecutive days, 8 h/day while performing moderate exercise. No decompression sickness or venous gas bubbles were detected. Pulmonary function tests, physical exams, blood analyses, arterial oxygen saturation monitoring, and x-rays showed no evidence of oxygen toxicity. These results suggest that a 100% oxygen, 9.5 psia pressure suit environment could avoid both decompression sickness and oxygen toxicity during EVAs of comparable duration and physical activity.

The advent of non-resupplied space missions of several year's duration poses some unique nutritional problems. Such problems have been of little consequence on missions that have been resupplied with natural foods at intervals of from one to two months or on missions that have been so short that the body's reserves of essential nutrients have not been depleted. Foods used on prolonged, non-resupplied missions must, in addition to providing a nutrient supply sufficient to meet ground-based nutritional requirements, also provide nutrients at levels needed to minimize any adverse effects stemming from weightlessness. Nutritional specifications must also reflect the now well recognized relationships between nutrition and such diseases as cancer and atherosclerosis.

One of the concerns for future spaceflight activities is the intermediate and/or long-term physiological or pathological complications which may develop in those individuals who engage in repetitive EVAs. Notwithstanding the thousands of exposures of individuals to decreased atmospheric pressures over the last 50 years, the syndrome of DCS still remains poorly understood, particularly as regards repeated exposure to pressure changes. The literature on the effects of repetitive exposure to low barometic pressures is confounding. Studies supporting an increased, decreased, and no change to susceptibility to DCS associated with repeated exposure to reduced pressures were found, and are discussed.

The otolith organs are the linear motion sensors of the mammalian system. As part of the vestibular system these small organs are located in the inner ear. Mathematically modeled, they consist of an overdamped second-order system with elastic, viscous damping, and mass elements. The governing equations of motion which describe the relative velocity of the mass with respect to the skull consist of a set of three coupled partial integral-differential equations. When these equations are nondimensionalized they yield three nondimensional parameters which characterize the dynamic response of the system. These nondimensional equations are solved numerically for the relative displacement of the otolith mass for various values of one of the three nondimensional parameters. The solutions generated are for a step change in skull velocity. These solutions indicate that the end organ long time response as well as limited maximum displacement requires a high degree of viscoelastic damping.

Life sciences research facilities planned for the U.S. Space Station will accommodate life sciences investigations addressing the influence of microgravity on living organisms. Current projects within the Life Sciences Space Station Program (LSSSP), the Life Sciences Space Biology (LSSB) and Extended Duration Crew Operations (EDCO) projects, will explore the physiological, clinical, and sociological implications of long duration space flight on humans and the influence of microgravity on other biological organisms/systems. Initially, the primary research will emphasize certifying man for routine 180-day stays on the Space Station. Operational crew rotations of 180 days or more will help reduce Space Station operational costs and minimize the number of Space Transportation System (STS) shuttle flights required to support Space Station.

The utility of analog environments as sources of data for future, long duration space missions is discussed. The undersea habitat is evaluated on a point by point basis for similarities and differences with Space Station and a possible Lunar Base. The comparability of Antarctic wintering-over stations is also considered. Critical issues for research are described as well as the requirement that participants be involved in the conduct of meaningful work.

Conventional oxygen separation from gases has a low extraction efficiency and requires a large energy source. An innovative low power, efficient oxygen extractor could capture free oxygen from the Martian atmosphere for use in life support systems. It might also be used during the lunar oxygen separation process from the soil or a Space Station ECLSS (Environmental Control and Life Support System) for oxygen concentration and distribution. Aquanautics Corporation received a Small Business Innovative Research (SBIR) Grant from NASA's Johnson Space center to develop such a system. The contract began in January 1988. The technology has involved a substantial research effort that is now entering into the first phase of prototype development. This paper discusses the technology in general terms and the specific work which is being performed for NASA to determine the feasibility for Martian applications.