Engineering topics
McCoy, Torin
Publications and source records attributed to McCoy, Torin.
Assessment of Ethanol Trends on the ISS
The International Space Station (ISS) Environmental Control and Life Support System (ECLSS) provides a working environment for six crewmembers through atmosphere revitalization and water recovery systems. In the last year, elevated ethanol levels have presented a unique challenge for the ISS ECLSS. Ethanol is monitored on the ISS by the Air Quality Monitor (AQM). The source of this increase is currently unknown. This paper documents the credible sources for the increased ethanol concentration, the monitoring provided by the AQM, and the impact on the atmosphere revitalization and water recovery systems.
NASA Astronaut Occupational Surveillance Program and Lifetime Surveillance of Astronaut Health, LSAH, Astronaut Exposures and Risk in the Terrestrial and Spaceflight Environment
United States Astronauts have a very unique occupational exposure profile. In order to understand these risks and properly address them, the National Aeronautics and Atmospheric Administration, NASA, originally created the Longitudinal Study of Astronaut Health, LSAH. The first LSAH was designed to address a variety of needs regarding astronaut health and included a 3 to 1 terrestrial control population in order to compare United States "earth normal" disease and aging to that of a microgravity exposed astronaut. Over the years that program has been modified, now termed Lifetime Surveillance of Astronaut Health, still LSAH. Astronaut spaceflight exposures have also changed, with the move from short duration shuttle flights to long duration stays on international space station and considerable terrestrial training activities. This new LSAH incorporates more of an occupational health and medicine model to the study of occupationally exposed astronauts. The presentation outlines the baseline exposures and monitoring of the astronaut population to exposures, both terrestrial, and in space.
The Story Behind the Numbers: Lessons Learned from the Integration of Monitoring Resources in Addressing an ISS Water Quality Anomaly
Beginning in June of 2010 an environmental mystery was unfolding on the International Space Station (ISS). The U.S. Water Processor Assembly (WPA) began to produce water with increasing levels of total organic carbon (TOC). A surprisingly consistent upward TOC trend was observed through weekly in-flight total organic carbon analyzer (TOCA) monitoring. As TOC is a general organics indicator, return of water archive samples was needed to make better-informed crew health decisions and to aid in WPA troubleshooting. TOCA-measured TOC was more than halfway to its health-based screening limit before archive samples could be returned on Soyuz 22 and analyzed. Although TOC was confirmed to be elevated, somewhat surprisingly, none of the typical target compounds were the source. After some solid detective work, it was confirmed that the TOC was associated with a compound known as dimethylsilanediol (DMSD). DMSD is believed to be a breakdown product of silicon-containing compounds present on ISS. A toxicological limit was set for DMSD and a forward plan developed for operations given this new understanding of the source of the TOC. This required extensive coordination with ISS stakeholders and innovative use of available in-flight and archive monitoring resources. Behind the numbers and scientific detail surrounding this anomaly, there exists a compelling story of multi-disciplinary awareness, teamwork, and important environmental lessons learned.
Got Mercury?
Many lamps used in various spacecraft contain elemental mercury, which is efficiently absorbed through the lungs as a vapor. The liquid metal vaporizes slowly at room temperature, but may be completely vaporized when lamps are operating. Because current spacecraft environmental control systems are unable to remove mercury vapors, we considered short-term and long-term exposures. Using an existing study, we estimated mercury vapor releases from lamps that are not in operation during missions lasting less than or equal to 30 days; whereas we conservatively assumed complete vaporization from lamps that are operating or being used during missions lasing more than 30 days. Based on mercury toxicity, the Johnson Space Center's Toxicology Group recommends stringent safety controls and verifications for any hardware containing elemental mercury that could yield airborne mercury vapor concentrations greater than 0.1 mg/m3 in the total spacecraft atmosphere for exposures lasting less than or equal to 30 days, or concentrations greater than 0.01 mg/m3 for exposures lasting more than 30 days.