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The ability to remove semi-volatile organic compounds such as alcohol from waste water streams has challenged the design of the International Space Station (ISS) water processor. The current ISS water processor utilizes an aqueous phase catalytic oxidation system to convert these organic compounds to their corresponding organic acids, and to some extent carbon dioxide, which are then easily removed via ion exchange resin. This oxidation system also provides a microbiological control function within the water processor. This paper summarizes testing conducted utilizing both simulated and real waste water on a development catalytic oxidizer. In addition, information is presented on the system schematic and reactor configuration planned for the upcoming Volatile Removal Apparatus flight experiment scheduled for STS 84 to be flown in May 1997.

The extended deployment of strategic deterrent submarines necessitated the onboard generation of respirable oxygen through electrolysis of water. Proton exchange membrane cells capable of generating oxygen at up to 1,600 milliamperes per square centimeter of cell surface area are currently in production. Recent technical advances allow submarines to utilize higher differential pressure cell stacks to permit the direct discharge of system fluids at submerged pressure while maintaining breathing oxygen at ambient pressure. Further developments permit the direct electrochemical reduction of carbon dioxide and the production of respirable oxygen in one electrochemical cell. This paper reports the improved performance of the upgraded SPE® electrolyzer configuration and preliminary performance data of the Submarine Advanced Integrated Life Support (SAILS) system for carbon dioxide reduction.

The original Shuttle Extravehicular Mobility Unit (EMU) Hard Upper Torso (HUT) configuration developed in1978 by Hamilton Standard and ILC, Dover had the arm attached in such a way that the shoulder bearing outer race was integral with the HUT. This method of attachment has been termed “planar arm.” During development, this configuration proved unacceptable because some astronauts and test subjects experienced difficulty, and in some cases pain, while donning. Interference occurred when the arms transitioned from vertical to horizontal as the HUT was entered (arms over head). At the time, designers needed to quickly resolve this issue and certify the EMU for the first Shuttle flight. The solution - pivot sockets - allowed the shoulder bearing to pivot relative to the HUT for donning purposes and then pivot back to allow for optimum arm performance. The pivoted HUT configuration has been very successful and is one of the design features that allows arm mobility and range in the EMU.

The Space Station Temperature and Humidity Control Condensing Heat Exchangers will be utilized to collect and remove atmospheric water vapor generated by the metabolic and hygienic activity of crew members. The porous hydrophilic coating within the heat exchangers will always be wet. Cabin air will continuously flow through the heat exchangers during system operation which makes them a potential site for microbial colonization. This paper summarizes the findings from an ongoing study which evaluates biofilm formation on wet hydrophilic coated panels compared to panels to which microbial control measures have been applied. The control measures evaluated are an antimicrobial agent within the coating and periodic drying.

The Space Station Temperature and Humidity Control Condensing Heat Exchangers will be utilized to remove and collect atmospheric water vapor generated by the metabolic and hygienic activity of crew members. The porous hydrophilic coating within the heat exchangers will be continually moist and in contact with a steady flow of cabin air which makes them susceptible to microbial growth. This paper summarizes the findings from an ongoing study to evaluate biofilm formation characteristics and microbial control techniques for the Space Station Condensing Heat Exchangers (CHX). This ongoing study examines whether the CHX's are susceptible to performance degrading microbial colonization with microbial challenge testing under simulated system environmental conditions. Furthermore, the three candidate microbial control approaches of periodic heating, periodic drying and incorporation of an antimicrobial agent, into the hydrophilic coating are evaluated.

The benefits and penalties associated with the generation of high pressure gases using the SPE® water electrolysis subsystem are presented. The Space Station has a number of requirements for oxygen and hydrogen generation at very high pressures (between 1000 and 6000 psia) including emergency pressurization and repressurization of habitability and laboratory modules, recharge of the Extravehicular Mobility Unit (EMU) oxygen tanks, and propulsion capability for Station reboost and attitude control. The traditional trade study parameters of weight, volume, power, and heat rejection are considered. The ramifications of the use of a high pressure, solid polymer electrolyte-based system are discussed with respect to Space Station safety and maintenance.