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Viewing 1 to 23 of 23
1995-07-01
Technical Paper
951683
David W. Koenig, Denetia M. Bell-Robinson, Susan M. Johnson, S. K. Mishra, Richard L. Sauer, Duane L. Pierson
One of the proposed methods for monitoring the microbial quality of the water supply aboard the International Space Station is membrane filtration. We adapted this method for space flight by using an off-the-shelf filter unit developed by Millipore. This sealed unit allows liquid to be filtered through a 0.45 μm cellulose acetate filter that sits atop an absorbent pad to which growth medium is added. We combined a tetrazolium dye with R2A medium to allow microbial colonies to be seen easily, and modified the medium to remain stable over 70 weeks at 25°C. This hardware was assembled and tested in the laboratory and during parabolic flight; a modified version was then flown on STS-66. After the STS-66 mission, a back-up plastic syringe and an all-metal syringe pump were added to the kit, and the hardware was used successfully to evaluate water quality aboard the Russian Mir space station.
1993-07-01
Technical Paper
932212
A. Steve Johnson, Chui-hsu Yang, Gautam D. Badhwar
Current dosimetric practices do not provide comprehensive classification of high-energy charged particle radiation, so that the ability to adequately project health risk to astronaut crews is limited. To address this shortcoming in dosimetry for Space Station missions, a new generation of active radiation monitors is being developed to supplement traditional dosimetry. One active monitor is a Tissue Equivalent Proportional Counter (TEPC) to measure the linear energy transfer (LET) spectrum of space radiation. Two versions of a second type of active monitor, the Charged Particle Directional Spectrometer (CPDS), will be deployed, one internal and one external to the Station. The CPDS consists of a stack of lithium-drifted silicon detectors used to classify the radiation by particle charge and energy. The comprehensive data set obtained by using the TEPC and the CPDS permits significant improvement in assessing crew radiation exposures.
2003-07-07
Technical Paper
2003-01-2405
James R. Akse, John T. Holtsnider, Helen Kliestik, Duane L. Pierson
The active control of problematic microbial populations aboard spacecraft, and within future lunar and planetary habitats is a fundamental Advanced Life Support (ALS) requirement to ensure the long-term protection of crewmembers from infectious disease, and to shield materials and equipment from biofouling and biodegradation. The development of effective antimicrobial coatings and materials is an important first step towards achieving this goal and was the focus of our research. A variety of materials were coated with antibacterial and antifungal agents using covalent linkages. Substrates included both granular media and materials of construction. Granular media may be employed to reduce the number of viable microorganisms within flowing aqueous streams, to inhibit the colonization and formation of biofilms within piping, tubing and instrumentation, and to amplify the biocidal activity of low aqueous iodine concentrations.
2008-06-29
Journal Article
2008-01-2081
Cynthia Cross, John F. Lewis, George C. Tuan
The Orion Crew and Service Modules are often compared to the Apollo Command and Service Modules due to their similarity in basic mission objective: both were dedicated to getting a crew to lunar orbit and safely returning them to Earth. Both spacecraft rely on the environmental control, life support and active thermal control systems (ECLS/ATCS) for the basic functions of providing and maintaining a breathable atmosphere, supplying adequate amount of potable water and maintaining the crew and avionics equipment within certified thermal limits. This assessment will evaluate the driving requirements for both programs and highlight similarities and differences. Further, a short comparison of the two system architectures will be examined including a side by side assessment of some selected system's hardware mass.
2008-06-29
Technical Paper
2008-01-2170
Eugene K. Ungar
Spacecraft that must operate in cold environments at reduced heat load are at risk of radiator freezing. For a vehicle that lands at the Lunar South Pole, the design thermal environment is 215 K, but the radiator working fluid must also be kept from freezing during the 0 K sink of transit. A radiator bypass flow setpoint control design such as those used on the Space Shuttle Orbiter and ISS would require more than 30% of the design heat load to avoid radiator freezing during transit - even with a very low freezing point working fluid. By changing the traditional active thermal control system (ATCS) architecture to include a regenerating heat exchanger inboard of the radiator and using a regenerator bypass flow control valve to maintain system setpoint, the required minimum system heat load can be reduced by more than half. This gives the spacecraft much more flexibility in design and operation. The present work describes the regenerator bypass ATCS setpoint control methodology.
2007-07-09
Technical Paper
2007-01-3218
John T. James
Carbon dioxide (CO2), a natural product of human metabolism, accumulates quickly in sealed environments when humans are present, and can induce headaches, among other symptoms. Major resources are expended to control CO2 levels to concentrations that are tolerable to the crews of spacecraft and submersible craft. It is not practical to control CO2 levels to those found in the ambient environment on earth. As NASA looks ahead to long-duration missions conducted far from earth, difficult issues arise related to the management and effects of human exposure to CO2. One is the problem of “pockets” of CO2 in the habitat caused by excess generation of the gas in one location without a mechanism to purge the area with fresh air. This results in the crew rebreathing CO2 from their exhaled breath, exposing them to a much higher concentration of CO2 than whole-module measurements would suggest. Another issue is the potential increased sensitivity to CO2 in microgravity.
2003-07-07
Technical Paper
2003-01-2646
Thomas Limero, Eric Reese, John Trowbridge, Richard Hohmann, John T. James
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.
2000-07-10
Technical Paper
2000-01-2433
Thomas Limero, Steve Beck, John T. James
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.
2008-06-29
Technical Paper
2008-01-1960
Dustin A. Ochoa, Matthew R. Vogel, Luis A. Trevino, Ryan A. Stephan
The optimum radiator configuration in hot lunar thermal environments is one in which the radiator is parallel to the ground and has no view to the hot lunar surface. However, typical spacecraft configurations have limited real estate available for top-mounted radiators, resulting in a desire to use the spacecraft's vertically oriented sides. Vertically oriented, flat panel radiators will have a large view factor to the lunar surface, and thus will be subjected to significant incident lunar infrared heat. Consequently, radiator fluid temperatures will need to exceed ~325 K (assuming standard spacecraft radiator optical properties) in order to provide positive heat rejection at lunar noon. Such temperatures are too high for crewed spacecraft applications in which a heat pump is to be avoided.
2002-07-15
Technical Paper
2002-01-2298
Thomas Limero, Steve W. Beck, John T. James
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.
2002-07-15
Technical Paper
2002-01-2407
Thomas Limero, Eric Reese, John Trowbridge, Richard Hohman, John T. James
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.
1999-07-12
Technical Paper
1999-01-2059
Thomas Limero, Eric Reese, Randy Peters, John T. James
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.
1999-07-12
Technical Paper
1999-01-2055
John T. James, Thomas F. Limero, John Trowbridge
Spacecraft modules that are last purged with clean air several months before they are entered by humans on orbit require careful management. The crew must not be exposed to harmful concentrations of air pollutants when they first enter. The magnitude of the pollution the crew will encounter depends on the volume of the module, the length of time since the last clean-air purge or scrub, the inherent offgassing rate of the materials in the module, the interior temperature of the module while offgassing occurs, and the system leak rate. The time of the last module purge or scrub can be several months before crew entry, so it is essential that the offgassing rate within the module be measured over a suitable interval of time to estimate pollution levels with confidence. Air samples were taken from the STS-74 Russian Docking Module, the STS-79 Spacehab, and the ISS Node 1 prior to launch to predict pollution levels at crew first entry.
2008-06-29
Technical Paper
2008-01-2125
John T. James
NASA has unique requirements for the development and application of air quality standards for human space flight. Such standards must take into account the continuous nature of exposures, the possibility of increased susceptibility of crewmembers to the adverse effects of air pollutants because of the stresses of space flight, and the recognition that rescue options may be severely limited in remote habitats. NASA has worked with the National Research Council Committee on Toxicology (NRCCOT) since the early 1990s to set and document appropriate standards. The process has evolved through 2 rounds. The first was to set standards for the space station era, and the second was to set standards for longer stays in space and update the original space station standards. The update was to be driven by new toxicological data and by new methods of risk assessment for predicting safe levels from available data. The last phase of this effort has been completed.
1991-07-01
Technical Paper
911406
Gerald V. Colombo, Clifford D. Jolly, Richard L. Sauer
The Microbial Check Valve (MCV) is used on the Space Shuttle to impart an iodine residual to the drinking water to maintain microbial control. Approximately twenty MCV locations have been identified in the Space Station Freedom design, each with a 90 day life. This translates to 2400 replacement units in 30 years of operation. An in situ regeneration concept has been demonstrated that will reduce this replacement requirement to less than 300 units based on data to date and potentially fewer as further regenerations are accomplished. A totally automated system will result in significant savings in crew time, resupply requirements and replacement costs. An additional feature of the device is the ability to provide a concentrated biocide source (200 mg/liter of I2) that can be used to superiodinate systems routinely or after a microbial upset. This program was accomplished under NASA Contract Number NAS9-18113.
1998-07-13
Technical Paper
981672
Cynthia Cross, Luis Trevino, James G. Laubach
Space suits for advanced missions have baselined radiators as the primary means of heat rejection in order to minimize consumables and logistics requirements. While radiators have been used in the active thermal control system for spacecraft since Gemini, the use of radiators in spacesuits introduces many unique requirements. These include the ability to reduce the amount of heat rejection when overcooling or overheating of the crew member is a concern. Overcooling can occur with low metabolic rates, cold environments or a combination of the two, and overheating can occur with high metabolic rates in a warm environment. The main goal of the Radiator Advanced Demonstrator (RAD) program is to build and fly a radiator on the current Extravehicular Mobility Unit (EMU) in order to verify thermal performance capabilities in actual flight conditions. The RAD incorporates an aluminum plate separated from the primary water panel with a silicone gasket.
1998-07-13
Technical Paper
981704
Daniel J. Barta, Keith Henderson
The Lunar-Mars Life Support Systems Test Project's Phase iii Test utilized the Variable Pressure Growth Chamber to contribute to the air revitalization and food requirements of a crew of four for a period of 91 days. USU-Apogee wheat was planted and harvested using a staged approach to provide more uniform levels of air revitalization and a staggered production of grain. The wheat crop provided an average of 1 .1 person-equivalents per day of carbon dioxide removal for air revitalization over the 91 -day human test. Over 34 kg of grain was harvested. it was found that staged cropping required more intensive management of the nutrient solution than single batch cropping. it was also found that salts which were biologically recovered from the plant biomass were as effective as conventional reagent-grade salts for use in the hydroponic nutrient solution.
1998-07-13
Technical Paper
981708
Marybeth A. Edeen, Karen D. Pickering
The Lunar Mars Life Support Test Project (LMLSTP) Phase III test was the final test in a series of tests conducted to evaluate regenerative life support systems performance over increasingly longer durations. The Phase III test broke new ground for the U.S. Space Program by being the first test to look at integration of biological and physical-chemical systems for air, water and solid waste recovery for a crew of four for 91 days. Microbial bioreactors were used as the first step in the water recovery system (WRS). This biologically based WRS continuously recovered 100% of the water used by the crew consistent with NASA's strict potable standards. The air revitalization system was a combination of physical-chemical hardware and wheat plants which worked together to remove and reduce the crew's metabolically produced carbon dioxide and provide oxygen.
1998-07-13
Technical Paper
981629
Mike Lawson, Cynthia Cross, Richard Stinson
A technology project to produce a new space suit for planetary applications started in January of 1997, with a thermal vacuum test of the system, including a suited crew member, expected in the year 2000. This will be a progress report on the activities that occurred during the project's first year. The four year project is funded out of Code M at NASA Headquarters and is an effort to integrate the latest EVA technology into a maintainable modular design. The project will use as much off-the-shelf hardware as practical in an effort to lower development cost and decrease development time. Three pressurized garment configurations will be evaluated and two different portable life support systems will be built. The first year was primarily spent developing laboratories, bench-top working laboratory subsystems, analytical models, and the overall requirements and architecture of the system.
1999-07-12
Technical Paper
1999-01-2117
Curt J. Wiederhoeft, John R. Schultz, William F. Michalek, Richard L. Sauer
Iodine is the disinfectant used in U.S. spacecraft potable water systems. Recent long-term testing on human subjects has raised concerns about excessive iodine consumption. Efforts to reduce iodine consumption by Shuttle crews were initiated on STS-87, using hardware originally designed to deiodinate Shuttle water prior to transfer to the Mir Space Station. This hardware has several negative aspects when used for Shuttle galley operations, and efforts to develop a practical alternative were initiated under a compressed development schedule. The alternative Low Iodine Residual System (LIRS) was flown as a Detailed Test Objective on STS-95. On-orbit, the LIRS imparted an adverse taste to the water due to the presence of trialkylamines that had not been detected during development and certification testing. A post-flight investigation revealed that the trialkylamines were released during gamma sterilization of the LIRS resin materials.
2000-07-10
Technical Paper
2000-01-2240
G. B. Sanders, J. R. Trevathan, D. I. Kaplan, T. A. Peters, R. S. Baird, J. S. Cook, M. L. McClean, K. Pauly
The ability to use local resources to “live off the land”, commonly referred to as In-Situ Resource Utilization (ISRU), is essential in establishing a long-term human presence and enabling the commercial development of space. The chief benefits of ISRU are that it can reduce the mass, cost, and risk of robotic and human exploration while providing capabilities that enable the commercial development of space. A key subset of ISRU which has significant cost and risk reduction benefits, and which requires a minimum of infrastructure, is In-Situ Consumable Production (ISCP). ISCP involves acquiring, manufacturing, and storing propellants, fuel cell reagents, and consumables for life support, scientific, and pneumatic equipment using resources available at the site of exploration. The NASA Johnson Space Center (JSC) is currently coordinating and focusing the Agency’s development of ISCP technologies and systems for robotic and human exploration.
1999-07-12
Technical Paper
1999-01-1936
Jay C. Almlie, Eugene K. Ungar, Frederick D. Smith
As part of NASA’s TransHab inflatable habitat program, a Radiation Shield Water Tank (RSWT) is being developed to provide a safe haven from peak solar particle events. The RSWT will provide an 11 ft. (3.35 m) diameter by 7 ft. (2.13 m) tall “safe haven” with a 2.26 in. (0.0574 m) thick wall of water for astronaut residence during peak solar events. The RSWT also functions as a water processing storage tank and must be capable of being filled and drained at will. Because of the unique shape of the RSWT, standard bellows and bladder designs cannot be used for inventory control. Therefore NASA has developed a bladderless tank where capillary forces govern the positioning of the liquid inventory. A combination of hydrophobic and hydrophilic membranes and wetting surfaces allows the tank to be filled and emptied as desired. In the present work, background on space-borne radiation is presented, the bladderless RSWT concept is described, and its theory of operation is discussed.
1999-07-12
Technical Paper
1999-01-1996
Siraj A. Jalali, Scott Andrea, Joseph R. Riccio, E. Steve Falls
Two types of supersonic jets, long and short, were designed for an advanced technology spacesuit ejector. Previously, a sonic jet was used in the ejector to improve its performance by reducing oxygen flow through thejetin order to achieve the required suit circulation. The manufacturing of long and short supersonic jets was a challenge which was met successfully by the Miniature Manufacturing Laboratory at NASA/JSC. The jets were tested and their performance was compared with the sonic jet, and it was found that both jets showed improved performance by achieving higher ejector mass ratios.
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