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An EMU water processing kit (Airlock Coolant Loop Recovery – A/L CLR) was developed as a corrective action to Extravehicular Mobility Unit (EMU) coolant flow disruptions experienced on the International Space Station (ISS) in May of 2004 and thereafter. Conservative schedules for A/L CLR use and component life were initially developed and implemented based on prior analysis results and analytical modeling. The examination of post-flight samples and EMU hardware in November of 2006 indicated that the A/L CLR kits were functioning well and had excess capacity that would allow a relaxation of the initially conservative schedules of use and component life. A relaxed use schedule and list of component lives were implemented thereafter. Since the adoption of the relaxed A/L CLR schedules of use and component lives, several A/L CLR kit items, transport loop water samples and sensitive EMU transport loop components have been examined to gage the impact of the relaxed requirements.

Following the Columbia accident, the EMUs (Extravehicular Mobility Units) onboard the ISS (International Space Station) went unused for an extended period of time. Upon startup, the units experienced a failure in the coolant systems. The failure resulted in a loss of EVA (Extravehicular Activity) capability from the US segment of the ISS. A failure investigation determined that chemical and biological contaminants and byproducts from the ISS Airlock Heat Exchanger, and the EMU itself, fouled the magnetically coupled pump in the EMU Transport Loop Fan/Pump Separator leading to a lack of coolant flow. Remediation hardware (the Airlock Coolant Loop Remediation water processing kit) and a process to periodically clean the EMU coolant loops on orbit were devised and implemented. The intent of this paper is to report on the successful implementation of the resultant hardware and process, and to highlight the go-forward plan.

Increased nickel concentrations in the IATCS coolant prompted a study of the corrosion rates of nickel-brazed heat exchangers in the system. The testing has shown that corrosion is occurring in a silicon-rich intermetallic phase in the braze filler of coldplates and heat exchangers as the result of a decrease in the coolant pH brought about by cabin carbon dioxide permeation through polymeric flexhoses. Similar corrosion is occurring in the EMU de-ionized water loop. Certain heat exchangers and coldplates have more silicon-rich phase because of their manufacturing method, and those units produce more nickel corrosion product. Silver biocide additions did not induce pitting corrosion at silver precipitate sites.

In August 1997 NASA/Marshall Space Flight Center (MSFC) began a test with the objective of monitoring the growth of microorganisms on material simulating the surface of the International Space Station (ISS) Temperature and Humidity Control (THC) Condensing Heat Exchanger (CHX). The test addressed the concerns of potential uncontrolled microbial growth on the surface of the THC CHX subsystem. For this study, humidity condensate from a closed manned environment was used as a direct challenge to the surfaces of six cascades in a test set-up. The condensate was collected using a Shuttle-type CHX within the MSFC End-Use Equipment Testing Facility. Panels in four of the six cascades tested were coated with the ISS CHX silver impregnated hydrophilic coating. The remaining two cascade panels were coated with the hydrophilic coating without the antimicrobial component, silver. Results of the fourteen-month study are discussed in this paper.

Design concepts for the International Space Station Water Processor (WP) will be validated as discrete flight experiments on-board the Space Shuttle Spacehab. This paper summarizes the results of a study into sample stability within a modified Teflon cell culture bag assembly to support an upcoming Spacehab evaluation of the WP Volatile Removal Assembly (VRA). Results indicate that a lack of adequate preservation results in significant sample analyte degradation over the course of 2-3 week due to increased microbial activity. Results were utilized for the definition of an optimal preservation approach based on the anticipated VRA Flight Experiment samples.

International Space Station includes a Joint Airlock in the U. S. on-orbit segment to support U. S. and Russian extravehicular activity (EVA). In this plan, the U. S. Extravehicular Mobility Unit (EMU) and the Russian Orlan-M spacesuit system share a common vehicle water coolant loop. Since the two spacesuit systems use different biocide additives and contain different non-metallic materials in their respective cooling water loops, steps are being taken to insure that no deleterious effects occur due to the mixing of Orlan-M and EMU coolant water. This paper describes the activities of the Russian and U.S. International Space Station and EVA teams to understand the implications of using both countries' EVA systems in such a deeply interconnected manner. The paper discusses a current U.S. test program and Russian analyses, and presents results to-date in an ongoing issue.

The current Shuttle EMU (Extravehicular Mobility Unit) uses expendable water to provide cooling to the EMU. For Space Station Freedom (SSF), one potential source of this water is the SSF potable water processor (PWP). Concerns exist about utilizing the SSF water for the EMU sublimator because the SSF PWP effluent may contain low soap concentrations. Traces of soap-like compounds (surfactants) have been shown to affect EMU sublimator performance at low concentrations. Results of testing indicate that a subscale sublimator functions equally well with both SSF PWP effluent and Shuttle quality deionized water. Furthermore, only minor performance anomalies are observed with water purposely spiked with maximum allowable concentrations of baseline shower soap. Not all surfactants are equally detrimental to sublimator performance. Testing with a full scale sublimator is the next step.

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 Water Reclamation and Management System (WRM) for the Environmental Control and Life Support System (ECLSS) has changed dramatically since Space Station Freedom (SSF) Restructure. What was two separate processors: the Potable Water Processor (PWP) and the Hygiene Water Processor (HWP), is now one combined system called the Water Processor (WP). This combined system is required to process the waste hygiene, handwash, and laundry waters, the Temperature and Humidity Control (THC) condensate, Shuttle fuel cell water, and the urine distillate, to produce potable quality water. The WP is composed of four major functions: waste water collection and storage, processed water storage and delivery, contaminant removal, and microbial separation between the waste and processed water. The two water storage and delivery functions are accomplished using vented bellows tanks and pumps.

Space Station Freedom uses a semi-closed loop recirculating waste water system to regenerate potable water. A specific series of depth and membrane filters can be employed prior to the waste water holding tank to eliminate bacteria at the earliest portion of the Water Processor. Several advantages accrue by using a cold sterilizing method for microbial control. This methodology i) reduces the weight and power requirements needed for a heat sterilizer and exchanger, and ii) significantly reduces biocorrosion and biofilm associated problems. A series of six filters and a two component resin bed was used to process a mixture of laundry water, shower water, and urine distillate in a ratio of 63:28:9 by volume. The final effluent was free of bacteria when grown on R2A agar. Gravimetric analysis was performed on 100 ml of downstream effluent from four filters and compared to the raw water.