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As mission length and the number and complexity of payload experiments increase, so does the probability of thermodegradation contingencies (e.g. fire, chemical release and/or smoke from overheated components or burning materials), which could affect mission success. When a thermodegradation event occurs on board a spacecraft, potentially hazardous levels of toxic gases could be released into the internal atmosphere. Experiences on board the Space Shuttle have clearly demonstrated the possibility of small thermodegradation events occurring during even relatively short missions. This paper will describe the Combustion Products Analyzer (CPA), which is being developed under the direction of the Toxicology Laboratory at Johnson Space Center to provide necessary data on air quality in the Shuttle following a thermodegradation incident.

The development of innovative technologies leading to flight hardware requires substantially more funding than typical commercial development efforts. Therefore, given the current resource constraints at NASA, funding must be invested wisely in new technologies having a high probability of meeting requirements established by NASA. The Toxicology Laboratory at Johnson Space Center (JSC) was faced with such a choice in selecting technology for a second-generation volatile organic analyzer to be used for monitoring spacecraft air quality in the later phases of the International Space Station (ISS). A method was needed that could fairly and accurately evaluate technologies and ultimately lead to the selection of the best technology. A systematic approach to identifying, reviewing, and rating advanced technologies was developed. Results from the second-generation VOA activities will be used to illustrate this unique technology selection process.

Experiences during the Shuttle and NASA/Mir programs illustrated the need for a real-time volatile organic analyzer (VOA) to assess the impact of air quality disruptions on the International Space Station (ISS). Toward this end, a joint development by the Toxicology Laboratory at Johnson Space Center and Graseby Dynamics (Watford, UK) produced a 1st generation VOA that has been delivered and is ready for the first 5 years of ISS operation. Criteria for the selection of the 1st generation VOA included minimizing the size, weight, and power consumption while maintaining analytical performance. Consequently, a VOA system based upon gas chromatography/ion mobility spectrometry (GC/IMS) was selected in the mid-90’s. A smaller, less resource-intensive device than the 1st generation VOA will be needed as NASA looks beyond ISS operations. During the past three years, efforts to reduce the size of ion mobility spectrometers have been pursued.

A replacement for the International Space Station's Volatile Organic Analyzer (VOA) is required because the VOA is at the end of its operational life after seven years on the International Space Station and it is too large for on-orbit replacement. The Sionex microAnalyzer™ is an ideal replacement for the VOA because it retains or exceeds the VOA's capability for detecting trace levels of air contaminants, and the microAnalyzer is small, low cost, and uses minimal spacecraft resources. The microAnalyzer has a volume of less than one-tenth of a cubic foot and it relies on gas chromatography and differential mobility spectrometry for accurate analysis of atmospheric contaminants. Several microAnalyzer units are being prepared for a Station Detailed Test Objective (SDTO) flight in 2008. This paper presents a brief overview of the microAnalyzer technology and provides data from the initial performance testing of the microAnalyzer on the ground in preparation for an upcoming SDTO.

A combustion products analyzer (CPA) was built for use on the Shuttle in response to several thermodegradation incidents during early flights. When the Toxicology Laboratory at Johnson Space Center (JSC) began to assess the air quality monitoring needs for the International Space Station (ISS), the CPA was the starting point for the design of a thermodegradation event monitor. The final product was significantly different from the CPA and was named the “compound specific analyzer-combustion products” (CSA-CP). One major change from the CPA was the replacement of the hydrogen fluoride sensor with an oxygen sensor. The focus of this paper will be the CSA-CP oxygen sensor’s ground testing, performance on ISS, and reduced pressure testing in response to a need on ISS.

Hydrazine (N2H4) and monomethylhydrazine (MMH) are used as propellants in several space-based applications, in which exposure limits as low as 2 ppb have been proposed. This paper reviews the development of hand-held, ambient-temperature instruments that use ion mobility spectrometry (IMS) in the detection of hydrazine and MMH. An instrument, based on early designs, detected hydrazine at 6 ppb with no interference from vapors except for ammonia, but exhibited slow response and recovery times. Performance of a hand-held IMS instrument that used water-reagent ion chemistry was unacceptable. An alternative, using acetone as the dopant reagent, also proved unacceptable, because ammonia-acetone clusters produced substantial interference in the detection of MMH. The goal of the present development effort was to eliminate ammonia interference through altering the ionization chemistry.

The Volatile Organic Analyzer (VOA) was the first instrument to routinely measure trace volatile organic compounds (VOCs) in near real-time aboard a manned spacecraft. Although the VOA was verified to accurately identify and quantify important target VOCs in the International Space Station atmosphere, its size and resource demands make the VOA unsuitable for use in exploration vehicles. Gas chromatography/differential mobility spectrometry (GC/DMS) is a technology that potentially can meet the size and resource constraints dictated by NASA's exploration mission scenarios. Additionally, it is expected that GC/DMS will meet or exceed the analytical performance of the VOA. This paper will provide a detailed explanation of DMS detection principles and describe the test plan being used to evaluate a GC/DMS brassboard in the NASA Johnson Space Center's Toxicology Laboratory. Initial results from the GC/DMS testing will be presented and recommendations for future GC/DMS work will be advanced.

The crew of flight 2A.1 that manned the International Space Station (ISS) assembly mission (STS-96) in May 1999 experienced symptoms that they attributed to poor air quality while working in the ISS modules. Some of these symptoms suggested that an accumulation of carbon dioxide (CO2) in the work area could have contributed to temporary health impacts on the crew. Currently, a fixed-position CO2 monitor in the FGB is the only means of measuring this air contaminant aboard ISS. As a result of this incident, NASA directed the Toxicology Laboratory at Johnson Space Center (JSC) to deliver a portable CO2 monitor for the next ISS assembly mission (STS-101). The Toxicology Laboratory developed performance requirements for a CO2 monitor and surveyed available CO2 monitoring technologies. The selected portable CO2 monitor uses nondispersive infrared spectroscopy for detection. This paper describes this instrument, its operation, and presents the results from ground-based performance testing.

Space Station Freedom (SSF) modules may be unattended for months during the Man-Tended Capability (MTC) phase of the program. The accumulation of airborne contamination from materials offgassing or contingency incidents (e.g., thermodegradation) raise concerns about crew health and safety from the first crew entry throughout the MTC phase. Computer modelling of the MTC phase, and experiences from previous space flight missions confirm that caution must be exercised during nominal first entry operations. This paper will describe first entry procedures used in the industrial setting and examples of the consequences when first-entry procedures were not followed. Experiences during the Skylab program will be presented to highlight the necessity for carefully planned operations. Anecdotal experiences from previous Spacelab missions and the results of first entry samples from the International Microgravity Laboratory (IML-1) will be detailed.

At last year’s International Conference on Environmental Systems, a technical paper was presented showing the loss of several compounds stored in dual sorbent tubes (DSTs) for long periods (>60 days). At the time, DSTs were virtually the only source available to the U.S. to assess trace contaminant concentrations in spacecraft air; therefore the compound losses were an important problem that needed to be addressed. This paper will update results from the DSTs returned on 9S and 10S Soyuz missions during the latter part of 2005. The data acquired from these DSTs will be compared to the 7S and 8S data presented last year. Discussion will focus on the reliability of correction factors and identification of any trends in the data. Additionally, test plans to investigate the cause of the problem and improve the DSTs will be detailed.

This paper will address an instrument designed for the measurement of volatile organic compounds (VOCs) within closed environments and specifically for one of the most difficult environments - that found within a space station. The constraints of low weight, size, power and consumables are combined with the needs for simplicity, reliability and maintainability together with the key ability to identify and quantify a wide range of organic compounds down to trace detection levels (ppb). Current technology to achieve these requirements, designed into a Volatile Organic Analyzer (VOA), uses a dual preconcentrator-GC-ion mobility spectrometry (GC-IMS) sequence with integral microprocessor. The VOA has achieved very high reliability and reproducibility; and has survived Shuttle launch forces. Details and results will be presented from VOA experiments in which the characterization of 30 compounds was addressed and methodology for their automated identification and quantitation was evolved.

The Volatile Organic Analyzer (VOA) provided valuable data on the gaseous trace contaminants in the atmosphere of the International Space Station (ISS) from January 2002 through May 2003. The VOA has two analytical channels that provide redundancy, but fuse failures caused the loss of one channel in January 2003 and the remaining channel in May 2003. In early 2005 on-orbit diagnostics verified failed fuses, and in December 2005 the fuses were replaced during an inflight maintenance (IFM) session. The VOA has provided data on the ISS atmosphere since it was reactivated in 2005. This paper summarizes the IFM procedures and presents the on-orbit data from 2006 that were used to revalidate the VOA.

The primary means to assess spacecraft air quality during a mission, for crew health purposes, has been archival air samplers that are returned to the ground for analysis. One such sampler is the Dual Sorbent Tube (DST) developed in late 2003 by the Toxicology group at the Johnson Space Center. The DSTs provided a low mass, low-volume sampler that was compatible with the constraints of the Soyuz return vehicle. The first set of DSTs, including positive control tubes, flew to the International Space Station (ISS) aboard Soyuz in January 2004 and they were returned in May 2004. The analytical recovery of compounds from the positive controls provides an indication of the stability of contaminants in the sampler. Analysis of the first returned set of positive controls revealed poor recoveries for several of the compounds. The low recoveries from the positive controls led to a study of compound stability on DSTs for long storage periods.

The Toxicology Laboratory at Johnson Space Center (JSC) had provided the combustion products analyzer (CPA) since the early 1990s to monitor the spacecraft atmosphere in real time if a thermodegradation event occurred aboard the Shuttle. However, as the operation of the International Space Station (ISS) grew near, an improved CPA was sought that would include a carbon monoxide sensor that did not have a cross-sensitivity to hydrogen. The Compound Specific Analyzer-Combustion Products (CSA-CP) was developed for use on the International Space Station (ISS). The CSA-CP measures three hazardous gases, carbon monoxide, hydrogen cyanide, and hydrogen chloride, as well as oxygen. The levels of these compounds in the atmosphere following a thermodegradation event serve as markers to determine air quality. The first permanent ISS crew performed the CSA-CP checkout operations and collected baseline data shortly after arrival aboard the ISS in December 2000.

The Volatile Organic Analyzer (VOA) was launched to the International Space Station (ISS) aboard STS-105 in August 2001. This instrument has provided the first near real-time data on the concentrations of trace contaminants in a spacecraft atmosphere. The VOA data will be used to assess air quality on ISS in nominal and contingency situations. Until the VOA presence on ISS, archival samples that were analyzed weeks if not months after the flight were the only means to obtain spacecraft air quality data on volatile organic compounds (VOCs). Especially in contingency situations, real-time data is important to help direct crew response and measure the effectiveness of decontamination efforts. The development and certification of the VOA has been chronicled in past ICES papers. This paper will discuss the preparation of the VOA for ISS operations. Also, examples of VOA data acquired during flight will be presented to demonstrate the value of the instrument in assessing the ISS environment.

There are many sources of air pollution that can threaten air quality during space missions. The International Space Station (ISS) is an extremely complex platform that depends on a multi-tiered strategy to control the risk of excessive air pollution. During the seven missions surveyed by this report, the ISS atmosphere was in a safe, steady-state condition; however, there were minor loads added as new modules were attached. There was a series of leaks of octafluoropropane, which is not directly toxic to humans, but did cause changes in air purification operations that disrupted the steady state condition. In addition, off-nominal regeneration of metal oxide canisters used during extravehicular activity caused a serious pollution incident.

Space-faring crews must have safe breathing air throughout their missions to ensure adequate performance and good health. Toxicological assessment of air quality depends on the standards that define acceptable air quality, measurements of pollutant levels during the flight, and reports from the crew on their in-flight perceptions of air quality. Air samples returned from ISS on flights 8A, UF2, 9A, and 11A were analyzed for trace pollutants. On average, the air during this period of operations was safe for human respiration. However, about 3 hours into the regeneration of 2 Metox canisters in the U.S. airlock on 20 February 2002 the crew reported an intolerable odor that caused them to stop the regeneration, take refuge in the Russian segment, and scrub air in the U.S. segment for 30 hours. Analytical data from grab samples taken during the incident showed that the pollutants released were characteristic of nominal air pollutants, but were present in much higher concentrations.

Space-faring crews must have safe breathing air throughout their missions to ensure adequate performance and good health. Toxicological assessment of air quality depends on applicable air-quality standards, measurements of pollutant concentrations, and crew reports of air quality. Samples of air were obtained during ingress and egress of the Zarya and Unity modules on missions 2A and 2A.1. The results from 2A suggest that trace pollutants were at safe levels and that there was good air exchange between the modules. Results from the 2A.1 flight also showed that trace pollutants were at acceptable concentrations; however, there was evidence of inadequate mixing between the modules during the hatch-open operations. Furthermore, the 2A.1 crew reported after the flight that the air quality seemed to cause symptoms during their operations in Zarya, particularly when more than one crewmember was working inside open panels for some time.

Space-faring crews must have safe breathing air throughout their missions to ensure adequate performance and good health. Toxicological assessment of air quality depends on the standards that define acceptable air quality, measurements of pollutant levels during the flight, and reports from the crew on their in-flight perceptions of air quality. Air samples from ISS flights 2A.2a, 2A.2b, 3A, and 4A were analyzed for trace pollutants. On average the air during each flight was safe for human respiration. However, there were reports from the crew that they experienced a headache when in certain areas, and strong odors were reported from specific locations of the ISS complex. Inspection of air samples in these locations suggested that several of the solvent-type pollutants (e.g. ethyl acetate, xylenes, and n-butanol) were present in concentrations that would cause a strong odor to be perceived by some individuals.

The Volatile organic analyzer (VOA) has been operated on the International Space Station (ISS) throughout 2002, but only periodically due to software interface problems. This instrument provides near real-time data on the concentration of target volatile organic contaminants in the spacecraft atmosphere. During 2002, a plan to validate the VOA operation on orbit was implemented using an operational scheme to circumvent the software issues. This plan encompassed simultaneous VOA sample runs and collection of archival air samples in grab sample containers (GSC). Agreement between the results from GSC and VOA samples is needed to validate the VOA for operational use. This paper will present the VOA validation data acquired through November 2002.