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A flex hose assembly containing aqueous coolant from the International Space Station (ISS) Internal Active Thermal Control System (IATCS) consisting of a 2 foot section of Teflon hose and quick disconnects (QDs) and a Special Performance Checkout Unit (SPCU) heat exchanger containing separate channels of IATCS coolant and iodinated water used to cool spacesuits and Extravehicular Mobility Units (EMUs) were returned for destructive analyses on Shuttle return to flight mission STS-114. The original aqueous IATCS coolant used in Node 1, the Laboratory Module, and the Airlock consisted of water, borate (pH buffer), phosphate (corrosion control), and silver sulfate (microbiological control) at a pH of 9.5 ± 0.5.

Since January 1999, the chemical and microbial state of the International Space Station (ISS) Internal Active Thermal Control System (IATCS) heat transport fluid (HTF) has been monitored by analysis of samples returned to Earth. Key chemical parameters have changed over time, including a drop in pH from the specified 9.5±0.5 to ≈8.4, an increase in the level of total inorganic carbon (TIC), total organic carbon (TOC) and dissolved nickel (Ni) in the HTF, and a decrease in the phosphate (PO4) level. In addition, silver (Ag) ion levels in the HTF decreased rapidly as Ag deposited on internal metallic surfaces of the system. The lack of available Ag ions coupled with changes in the HTF chemistry has resulted in a favorable environment for microbial growth. Counts of heterotrophic bacteria have increased from <10 colony-forming units (CFUs)/100 mL to 106 to 107 CFUs/100 mL.

The fluid in the Internal Active Thermal Control System (IATCS) of the International Space Station (ISS) is water based. The fluid in the ISS Laboratory Module and Node 1 initially contained a mix of water, phosphate (corrosion control), borate (pH buffer), and silver sulfate (Ag2SO4) (microbial control) at a pH of 9.5±0.5. Over time, the chemistry of the fluid changed. Fluid changes included a pH drop from 9.5 to 8.3 due to diffusion of carbon dioxide (CO2) through Teflon® (DuPont) hoses, increases in dissolved nickel (Ni) levels, deposition of silver (Ag) to metal surfaces, and precipitation of the phosphate (PO4) as nickel phosphate (NiPO4). The drop in pH and unavailability of a antimicrobial has provided an environment conducive to microbial growth. Microbial levels in the fluid have increased from <10 colony-forming units (CFUs)/100 mL to 106 CFUs/100 mL.

NASA/ Marshall Space Flight Center (NASA/MSFC) is responsible for the design and fabrication of a Portable Fan Assembly (PFA) for the International Space Station (ISS). The PFA will be used to enhance air circulation inside the ISS modules as needed for crew comfort and for rack rotation. The PFA consists of the fan on-orbit replaceable unit (ORU) and two noise suppression packages (silencers). The fan ORU will have a mechanical interface with the Seat Track Equipment Anchor Assembly, in addition to the power supply module which includes a DC-DC converter, on/standby switch, speed control, power cable and connector. This paper provides a brief development history, including the criteria used for the fan, and a detailed description of the PFA operational configurations. Space Station requirements as well as fan performance characteristics are also discussed.

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.

Contaminating microorganisms pose a serious potential risk to the crew's well being and water system integrity aboard the International Space Station (ISS). We are developing a gene-based microbial monitor that functions by replicating specific segments of DNA as much as 1012 x. Thus a single molecule of DNA can be replicated to detectable levels, and the kinetics of that molecule's accumulation can be used to determine the original concentration of specific microorganisms in a sample. Referred to as the polymerase chain reaction (PCR), this enzymatic amplification of specific segments of the DNA or RNA from contaminating microbes offers the promise of rapid, sensitive, quantitative detection and identification of bacteria, fungi, viruses, and parasites. We envision a small instrument capable of assaying an ISS water sample for 48 different microbes in a 24 hour period.

The monitoring of spacecraft life support systems for the presence of health threatening microorganisms is paramount for crew well being and successful completion of missions. The union of the molecular biology techniques of DNA probe hybridization and polymerase chain reaction (PCR) offers a powerful method for the detection, identification, and quantification of microorganisms and viruses. This report is an evaluation of the state of PCR science as it applies to the needs of NASA to develop a microbiology monitor for use aboard spacecraft, and a set of recommendations as to the design of a PCR-based microbial monitor for recycled water aboard the ISS.

NASA-Marshall Space Flight Center (MSFC) has an interest in an automated in-line monitor that can detect the presence of microbial contamination in recovered water. Ideally, this system should also be able to identify and enumerate the microbial contaminant. The Viable Microbial Monitor (VM2) is based on conductance microbiology which depends on the well documented ability of microorganisms to change the electrochemical properties of their growth medium during incubation. The VM2 is intended for the rapid detection of bacterial or fungal contamination in water and other samples. From October 1992 to July 1993, NASA-MSFC sponsored a Microbial In-line Monitor (MIM) study to evaluate the VM2 for its ability to detect ten microorganism species (9 bacteria and 1 yeast) recovered from Water Recovery Tests (WRT) conducted at MSFC. These WRT isolates may represent the microbes that have potential to contaminate a water recovery system.

Early detection of microbial contaminants in reclaimed water was investigated using conductivity measurements of cultured samples. Culture data were obtained by using conductivity electronics and a personal computer equipped with an analog-digital converter and multiplexer. The software was programmed to monitor 54 cultures. The cultures were incubated for up to 48 hours at 35°C. The real-time conductivity data obtained from these cultured samples produces curves comprised of multiple data points over time. Using laboratory cultures for conductivity measurements, growth was detected within 12-24 hours with inocula in the range of less than 100 to 105 colony forming units per ml (CFU/ml). Detection times ranged from 20-35 hours for reclaimed water samples, and bacteria in untreated waste-waters were detected in 2-15 hours.