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At least 325 records · Page 18

Design of an oxygen sensor with automatic self-testing and calibration capability

Future long duration manned space missions require a reliable sensor to monitor cabin oxygen (O2) pressure. This paper presents a concept for a solid zirconia O2 sensor capable of automatic self-test and calibration without the need for consumable materials. The operation and the techniques used to verify proper performance and to calibrate the sensor are described. Coulometric measurements are used to calculate the cabin O2 pressure without comparison to any reference state; potentiometric measurements are simple and reliable. The use of independent measurements permits the verification of results obtained with either technique. The design includes fault diagnostics which takes corrective action if a fault occurs.

Cusick, Robert J.↗

Structural Configuration Analysis of Crew Exploration Vehicle Concepts

Structural configuration modeling and finite element analysis of crew exploration vehicle (CEV) concepts are presented. In the structural configuration design approach, parametric solid models of the pressurized shell and tanks are developed. The CEV internal cabin pressure is same as in the International Space Station (ISS) to enable docking with the ISS without an intermediate airlock. Effects of this internal pressure load on the stress distribution, factor of safety, mass and deflections are investigated. Uniform 7 mm thick skin shell, 5 mm thick shell with ribs and frames, and isogrid skin construction options are investigated. From this limited study, the isogrid construction appears to provide most strength/mass ratio. Initial finite element analysis results on the service module tanks are also presented. These rapid finite element analyses, stress and factor of safety distribution results are presented as a part of lessons learned and to build up a structural mass estimation and sizing database for future technology support. This rapid structural analysis process may also facilitate better definition of the vehicles and components for rapid prototyping. However, these structural analysis results are highly conceptual and exploratory in nature and do not reflect current configuration designs being conducted at the program level by NASA and industry.

Mukhopadhyay, V.↗

Real-time Contaminant Evolution from a CO 2 Scrubber

Spaceflight requires recycling and revitalization of cabin air within the spacecraft during missions. Marshall Space Flight Center’s (MSFC) Environmental Control and Life Support Systems Engineering Development Branch (ES-62), develops and tests novel regenerative life support systems, supports the International Space Station (ISS) operations, and plans life support for future missions, such as Gateway and Mars transit.

Jennifer G Williams↗

Proteomic Assessment of Fluid Shifts and Association with Visual Impairment and Intracranial Pressure in Twin Astronauts

BACKGROUND: Astronauts participating in long duration space missions are at an increased risk of physiological disruptions. The development of visual impairment and intracranial pressure (VIIP) syndrome is one of the leading health concerns for crew members on long-duration space missions; microgravity-induced fluid shifts and chronic elevated cabin CO2 may be contributing factors. By studying physiological and molecular changes in one identical twin during his 1-year ISS mission and his ground-based co-twin, this work extends a current NASA-funded investigation to assess space flight induced "Fluid Shifts" in association with the development of VIIP. This twin study uniquely integrates physiological and -omic signatures to further our understanding of the molecular mechanisms underlying space flight-induced VIIP. We are: (i) conducting longitudinal proteomic assessments of plasma to identify fluid regulation-related molecular pathways altered by long-term space flight; and (ii) integrating physiological and proteomic data with genomic data to understand the genomic mechanism by which these proteomic signatures are regulated. PURPOSE: We are exploring proteomic signatures and genomic mechanisms underlying space flight-induced VIIP symptoms with the future goal of developing early biomarkers to detect and monitor the progression of VIIP. This study is first to employ a male monozygous twin pair to systematically determine the impact of fluid distribution in microgravity, integrating a comprehensive set of structural and functional measures with proteomic, metabolomic and genomic data. This project has a broader impact on Earth-based clinical areas, such as traumatic brain injury-induced elevations of intracranial pressure, hydrocephalus, and glaucoma. HYPOTHESIS: We predict that the space-flown twin will experience a space flight-induced alteration in proteins and peptides related to fluid balance, fluid control and brain injury as compared to his pre-flight protein/peptide signatures. Conversely, the trajectory of these protein signatures will remain relatively constant in his ground based co-twin. METHODS: We are using proteomic and standard immunoelectrophoresis techniques to delineate the change in protein signatures throughout the course of a long duration space flight in relation to the development of VIIP. We are also applying a novel cell-based metaboloic organ system assay ("Organs on a Plate") to address how these circulating biomarkers affect physiological processes at the cellular and organ level which could result in VIIP symptoms. These molecular data will be correlated with physiological measures (eg. extra and intracellular fluid volume, vascular filling/flow patterns, MRI, and Optic Coherence Tomography. DISCUSSION: Pre- and in-flight data collection is in progress for the space-flown twin, and similar data have been obtained from the ground-based twin. Biosamples will be batch processed when received from ISS after the conclusion of the 1-year mission. Omic and Physiological measures from the twin astronauts will be compared to similar data being collected on twin subjects who participated in simulated microgravity study. bed rest study.

Rana, Brinda K.↗

Electrodynamic Dust Shield for Space Applications

The International Space Exploration Coordination Group (ISECG) has chosen dust mitigation technology as a Global Exploration Roadmap (GER) critical technology need in order to reduce life cycle cost and risk, and increase the probability of mission success. NASA has also included Particulate Contamination Prevention and Mitigation as a cross-cutting technology to be developed for contamination prevention, cleaning and protection. This technology has been highlighted due to the detrimental effect of dust on both human and robotic missions. During manned Apollo missions, dust caused issues with both equipment and crew. Contamination of equipment caused many issues including incorrect instrument readings and increased temperatures due to masking of thermal radiators. The astronauts were directly affected by dust that covered space suits, obscured face shields and later propagated to the cabin and into the crew's eyes and lungs. Robotic missions on Mars were affected when solar panels were obscured by dust thereby reducing the effectiveness of the solar panels. The Electrostatics and Surface Physics Lab in Swamp Works at the Kennedy Space Center has been developing an Electrodynamic Dust Shield (EDS) to remove dust from multiple surfaces, including glass shields and thermal radiators. This technology has been tested in lab environments and has evolved over several years. Tests of the technology include reduced gravity flights (one-sixth g) in which Apollo Lunar dust samples were successfully removed from glass shields while under vacuum (10(exp -6) kPa).

ISECG↗

Electrodynamic Dust Shield for Space Applications

The International Space Exploration Coordination Group (ISECG) has chosen dust mitigation technology as a Global Exploration Roadmap (GER) critical technology need in order to reduce life cycle cost and risk, and increase the probability of mission success. NASA has also included Particulate Contamination Prevention and Mitigation as a cross-cutting technology to be developed for contamination prevention, cleaning and protection. This technology has been highlighted due to the detrimental effect of dust on both human and robotic missions. During manned Apollo missions, dust caused issues with both equipment and crew. Contamination of equipment caused many issues including incorrect instrument readings and increased temperatures due to masking of thermal radiators. The astronauts were directly affected by dust that covered space suits, obscured face shields and later propagated to the cabin and into the crew's eyes and lungs. Robotic missions on Mars were affected when solar panels were obscured by dust thereby reducing the effectiveness of the solar panels. The Electrostatics and Surface Physics Lab in Swamp Works at the Kennedy Space Center has been developing an Electrodynamic Dust Shield (EDS) to remove dust from multiple surfaces, including glass shields and thermal radiators. This technology has been tested in lab environments and has evolved over several years. Tests of the technology include reduced gravity flights (6g) in which Apollo Lunar dust samples were successfully removed from glass shields while under vacuum (1 millipascal). Further development of the technology is underway to reduce the size of the EDS as well as to perform material and component testing outside of the International Space Station (ISS) on the Materials on International Space Station Experiment X (MISSE-X). This experiment is designed to verify that the EDS can withstand the harsh environment of space and will look to closely replicate the solar environment experienced on the moon. A second flight opportunity exists to provide an EDS to several companies as part of NASA's Lunar CATALYST program. The current mission concept would fly the EDS on the footpad of one of the Lunar CATALYST vehicles. To determine the effectiveness of the EDS system, image analysis will be performed on the footpad before, during and after EDS activation. If successful in these test flights, the Technology Readiness Level (TRL) of the EDS will be raised to a sufficient level to be used in the protection of mission equipment for future NASA and commercial missions to the moon, asteroids, and Mars.

Dust mitigation↗

Challenges in the development of the orbiter atmosphere revitalization subsystem

The space shuttle orbiter atmospheric revitalization subsystem provides thermal and contaminant control as well as total- and oxygen partial-pressure control of the environment within the orbiter crew cabin. Challenges that occurred during the development of this subsystem for the space shuttle orbiter are described. The design of the rotating hardware elements of the system (pumps, fans, etc.) required significant development to meet the requirements of long service life, maintainability, and high cycle-fatigue life. As a result, a stringent development program, particularly in the areas of bearing life and heat dissipation, was required. Another area requiring significant development was cabin humidity control and condensate collection.

Prince, R. N.↗

Case Studies in Crewed Spacecraft Environmental Control and Life Support System Process Compatibility and Cabin Environmental Impact

Contamination of a crewed spacecraft's cabin environment leading to environmental control and life support system (ECLSS) functional capability and operational margin degradation or loss can have an adverse effect on NASA's space exploration mission figures of merit-safety, mission success, effectiveness, and affordability. The role of evaluating the ECLSS's compatibility and cabin environmental impact as a key component of pass trace contaminant control is presented and the technical approach is described in the context of implementing NASA's safety and mission success objectives. Assessment examples are presented for a variety of chemicals used in vehicle systems and experiment hardware for the International Space Station program. The ECLSS compatibility and cabin environmental impact assessment approach, which can be applied to any crewed spacecraft development and operational effort, can provide guidance to crewed spacecraft system and payload developers relative to design criteria assigned ECLSS compatibility and cabin environmental impact ratings can be used by payload and system developers as criteria for ensuring adequate physical and operational containment. In additional to serving as an aid for guiding containment design, the assessments can guide flight rule and procedure development toward protecting the ECLSS as well as approaches for contamination event remediation.

Perry, J. L.↗

Portable Multigas Monitors for International Space Station

The Environmental Health System (EHS) on International Space Station (ISS) includes portable instruments to measure various cabin gases that acutely impact crew health. These hand-held devices measure oxygen, carbon dioxide, carbon monoxide, hydrogen chloride and hydrogen cyanide. The oxygen and carbon dioxide units also serve to back up key functions of the Major Constituent Analyzers. Wherever possible, commercial off-the-shelf (COTS) devices are employed by EHS to save development and sustaining costs. COTS hardware designed for general terrestrial applications however has limitations such as no pressure compensation, limited life of the active sensor, calibration drift, battery issues, unpredictable vendor support and obsolescence. The EHS fleet (inflight and ground inventory) of instruments is both aging and dwindling in number. With the retirement of the US Space Shuttle, maintenance of on-orbit equipment becomes all the more difficult. A project is underway to search for gas monitoring technology that is highly reliable and stable for years. Tunable Diode Laser Spectroscopy (TDLS) seems to be the front-runner technology, but generally is not yet commercially available in portable form. NASA has fostered the development of TDLS through the Small Business Innovative Research (SBIR) program. A number of gases of interest to the aerospace and submarine communities can be addressed by TDLS including the list mentioned above plus hydrogen fluoride, ammonia and water (humidity). There are several different forms of TDLS including photoacoustic and direct absorption spectroscopy using various multipass cell geometries. This paper describes the history of portable gas monitoring on NASA spacecraft and provides a status of the development of TDLS based instruments. Planned TDLS flight experiments on ISS could lead both to operational use on ISS and important roles in future Exploration spacecraft and habitats.

Mudgett, Paul D.↗

A regenerable solid amine CO2 concentrator for space station

A regenerable solid amine CO2 control system, which employs water vapor for desorption, is being developed for potential use on long duration space missions. During cyclic operation, CO2 is first absorbed from the cabin atmosphere onto the granular amine. Steam is then used to heat the solid amine bed and desorb the CO2. This paper describes the solid amine system operation and application to the Shuttle Orbiter, Manned Space Platform (MSP) and Space Operations Center (SOC). The importance and interplay of system performance parameters are presented together with supporting data and design characteristics.

Boehm, A. M.↗

On-Orbit Measurements of the ISS Atmosphere by the Vehicle Cabin Atmosphere Monitor

We report on trace gas and major atmospheric constituents results obtained by the Vehicle Cabin Atmosphere Monitor (VCAM) during operations aboard the International Space Station (ISS). VCAM is an autonomous environmental monitor based on a miniature gas chromatograph/mass spectrometer. It was flown to the ISS on shuttle mission STS-131 and commenced operations on 6/10/10. VCAM provides measurements of ppb-to-ppm levels of volatile trace-gas constituents, and of the atmospheric major constituents (nitrogen, oxygen, argon, and carbon dioxide) in a space vehicle or station. It is designed to operate autonomously and maintenance-free, approximately once per day, with a self-contained gas supply sufficient for a one-year lifetime. VCAM is designed to detect and identify 90% of the target compounds at their 180-day Spacecraft Maximum Allowable Concentration levels.

cabin atmosphere↗

The Role of System Compatibility and Cabin Environmental Impact Assessment in Environmental Control and Life Support System Design and Flight Operations

Contamination of a crewed spacecraft's cabin environment leading to ECLS system functional capability and operational margin degradation or loss can have an adverse effect on NASA's space exploration mission figures of merit-safety, mission success, effectiveness, and affordability. Experience gained during the International Space Station program has shown the vital role that evaluating ECLS system compatibility and cabin environmental impact serves as a passive trace contaminant control tool which can provide guidance to crewed spacecraft system and payload developers relative to designing for minimum risk. As well, such evaluations can aid in guiding containment design, developing flight rules and procedures suitable for protecting the ECLS system and cabin environment, and defining contamination event remediation approaches. The approach to evaluating ECLS system compatibility and cabin environmental impact developed during the ISS program is presented and its role in future exploration spacecraft design is discussed.

Peery, Jay L.↗

Design concept definition study for an improved shuttle waste collection subsystem

A no-risk approach for developing an Improved Waste Collection Subsystem (WCS) for the shuttle orbiter is described. The GE Improved WCS Concept builds on the experience of 14 Shuttle missions with over 400 man-days of service. This concept employs the methods of the existing flight-proven mature design, augmenting them to eliminate foreseen difficulties and to fully comply with the design requirements. The GE Improved WCS Concept includes separate storage for used wipes. Compaction of the wipes provides a solution to the capacity problem, fully satisfying the 210 man-day storage requirement. The added feature of in-flight serviceable storage space for the wipes creates a variable capacity feature which affords redundancy in the event of wipes compaction system failure. Addition of features permitting in-flight servicing of the feces storage tank creates a variable capacity WCS with easier post-flight servicing to support rapid turnaround of the Shuttle orbiter. When these features are combined with a vacuum pump to evacuate wipes and fecal storage tanks through replaceable odor/bacteria filters to the cabin, the GE Improved WCS satisfies the known requirements for Space Station use, including no venting to space.

Source record↗

Analytical Methods and Testbeds for Characterizing Adsorbents and Catalysts for Atmosphere Revitalization of Crewed Spacecraft

Spacecraft environmental control and life support systems (ECLSS) include a number of air revitalization (AR) technologies to provide breathable air and a comfortable living environment to the crew. Crew health and comfort is ensured by controlling human produced CO2 (1 kg person-1 day-1) and water vapor (~2 kg person-1 day-1), and by removing trace contaminants (TCs) from cabin air. These life support functions on-board the International Space Station (ISS) are carried out by the Carbon Dioxide Removal Assembly (CDRA), the Water Processor Assembly (WPA), and the trace contaminant control system (TCCS). During the development of the TCCS, new analytical and theoretical methods were developed in the 1970s for characterizing adsorption and desorption characteristics of activated carbons for the purpose of designing suitable AR technologies required for controlling airborne trace contaminants within spacecraft cabins during long exploration missions. The TCCS removes harmful volatile organic compounds and other trace contaminants from the circulating air. It consists of a granular activated carbon (GAC) bed for the removal of high molecular weight contaminants and ammonia followed by a heated catalytic bed for low molecular weight hydrocarbons. The high temperature catalytic oxidizer (HTCO) of the TCCS, which operates at 400°C and requires 120W average power, removes low molecular weight compounds such as carbon monoxide (CO), formaldehyde (CH2O), and methane (CH4), that pass through the GAC bed. The Air Revitalization Laboratory at the Kennedy Space Center (KSC) was established to develop new analytical methods for evaluating emerging ECLSS technologies for use in future AR architectures. General properties of adsorbents and catalysts are required for trace contaminant control system design calculations and vendor-supplied data are seldom available at relevant process conditions of interest to spacecraft cabin applications. To address this shortcoming, appropriate testbeds were developed to measure the desired properties of AR technologies being considered for use in ECLS architectures. Generally, the testbeds developed at KSC challenge the test media (activated carbon, impregnated activated carbon, catalysts, zeolites, solid amines, or pleated filters) with simulated spacecraft gas streams containing representative mixtures of trace contaminants (volatile organic compounds, ammonia, CO, CO2, or siloxanes) at the flow rates, temperatures, and relative humidity that will be encountered within manned spacecraft. Work performed at KSC funded by NASA’s Advanced Exploration (AES) Program has included: Identifying candidate sorbents to replace commercially obsolete impregnated carbons for NH3 control within the TCCS, characterizing their adsorptive capacities using simulated spacecraft gas streams, and ranking their appropriateness in various AR applications; evaluating novel low temperature catalysts for controlling CO and formaldehyde by traditional and photocatalytic methods for trace contaminant control; development of analytical methods to assess regenerable solid amine performance for CO2 control via pressure swing adsorption. The Air Revitalization lab was also funded to study trace contaminant control by other NASA programs. These include: screening of candidate sorbents for the design of new Charcoal HEPA Integrated Particle Scrubber (CHIPS) filters for removing siloxanes from cabin air; characterizing the performance of an impregnated activated carbon at low humidity for use in ORION ECLS; screening of sorbents for protecting the Sabatier 2.0 catalyst from DMSO2, siloxanes, NH3, and solid amine byproducts.

Monje, Oscar↗

Improving survival after tissue vaporization (Ebullism)

Exposure of unprotected humans to altitudes above 63,000 ft results in ebullism. Ebullism occurs when the vapor pressure of tissues is less than the ambient pressure and the tissues spontaneously 'boil'. This may result in rapid unconsciousness, cardiac vaporlock, pulmonary collapse, cerebral anoxia, and sometimes even death. Potential places for this include EVA accidents in space, aircraft experiencing rapid decompression at high altitudes with cabin or pressure suit failure, and accidents during pressure suit training exercises. The pathophysiology of ebullism was studied in the 40's to 60's using animal models. There is one report of a prolonged, unprotected human exposure and several anecdotal of unprotected short term exposures to near vacuum. In addition to pulmonary and neurologic concerns, unprotected exposure of the head may result in freezing of the corneal surface of the eye. Surface eye freezing may impair vision and significantly impact mission completion. At this time, little data are available on the effectiveness of conventional treatment protocols, such as hyperbaric oxygen, for ebullism induced injuries. Research is needed to assess the efficacy of other adjunctive therapies such as high frequency ventilation and cerebral protective drugs that are still under development.

Stegmann, Barbara J.↗

Development of Testing Station for Prototype Rover Thermal Subsystem

In order to successfully and efficiently explore the moon or other planets, a vehicle must be built to assist astronauts as they travel across the surface. One concept created to meet this need is NASA's Space Exploration Vehicle (SEV). The SEV, a small pressurized cabin integrated onto a 12-wheeled chassis, can support two astronauts up to 14 days. Engineers are currently developing the second generation of the SEV, with the goal of being faster, more robust, and able to carry a heavier payload. In order to function properly, the rover must dissipate heat produced during operation and maintain an appropriate temperature profile inside the rover. If these activities do not occur, components of the rover will start to break down, eventually leading to the failure of the rover. On the rover, these requirements are the responsibility of the thermal subsystem. My project for the summer was to design and build a testing station to facilitate the design and testing of the new thermal subsystem. As the rover develops, initial low fidelity parts can be interchanged for the high fidelity parts used on the rover. Based on a schematic of the proposed thermal system, I sized and selected parts for each of the components in the thermal subsystem. For the components in the system that produced heat but had not yet been finalized or fabricated, I used power resistors to model their load patterns. I also selected all of the fittings to put the system together and a mounting platform to support the testing station. Finally, I implemented sensors at various points in the system to measure the temperature, pressure, and flow rate, and a data acquisition system to collect this information. In the future, the information from these sensors will be used to study the behavior of the subsystem under different conditions and select the best part for the rover.

Burlingame, Kaitlin↗

Cabin Thermal Management Analysis for SuperTruck II Next-Generation Hybrid Electric Truck Design

In this article, we present a multistage, coupled thermal management simulation approach, informed by physical testing where available, to aid design decisions for PACCAR's SuperTruck II hybrid truck cabin concept. Focus areas include cabin insulation, battery sizing, and sleeper curtain position, as well as heating, ventilating, and air-conditioning (HVAC) component and accessory configurations, to maintain or improve thermal comfort while saving energy. The authors analyzed weather data and determined the national vehicle miles traveled weighted temperature and solar conditions for long-haul trucks. Example weather day profiles were selected to approximate the 5th and 95th percentile weighted conditions. A daylong drive cycle was developed to impose appropriate external wind conditions during rest and driving periods. Using the National Renewable Energy Laboratory's vehicle HVAC modeling and simulation tool VTCab, HVAC load design trade-off studies for the new truck geometry concept were completed. Parameters analyzed included effects of paint color, insulation, glass transmissivity, and curtain location. Simulation results helped with early design material selections for efficient cabin climate control. A detailed three-dimensional computer-aided engineering (CAE), computational fluid dynamics (CFD), radiation, and human physiology co-simulation, referred to in this article as CAE Thermal-CFD, was used to evaluate thermal comfort and energy impacts of diffuser configurations and air supply settings in driving and hoteling modes. Analysis revealed that it is more difficult to heat the cabin in hoteling mode during the winter than to cool the space in the summer. This seasonal load profile drives the requirement of additional energy storage for heating comfort. To determine the battery capacity requirement, multiday HVAC operation drive cycle simulations were then completed, showing that a 15-kWh battery would be required for HVAC operation during hoteling. Results helped reduce cabin thermal loads, determine component sizing requirements, and improve occupant comfort to save fuel and contribute to the economic viability of the hybrid system.

33 ADVANCED PROPULSION SYSTEMS↗

Risks and issues in fire safety on the Space Station

A fire in the inhabited portion of a spacecraft is a greatly feared hazard, but fire protection in space operations is complicated by two factors. First, the spacecraft cabin is an enclosed volume, which limits the resources for fire fighting and the options for crew escape. Second, an orbiting spacecraft experiences a balance of forces, creating a near-zero-gravity (microgravity) environment that profoundly affects the characteristics of fire initiation, spread, and suppression. The current Shuttle Orbiter is protected by a fire-detection and suppression system whose requirements are derived of necessity from accepted terrestrial and aircraft standards. While experience has shown that Shuttle fire safety is adequate, designers recognize that improved systems to respond specifically to microgravity fire characteristics are highly desirable. Innovative technology is particularly advisable for the Space Station, a forthcoming space community with a complex configuration and long-duration orbital missions, in which the effectiveness of current fire-protection systems is unpredictable. The development of risk assessments to evaluate the probabilities and consequences of fire incidents in spacecraft are briefly reviewed. It further discusses the important unresolved issues and needs for improved fire safety in the Space Station, including those of material selection, spacecraft atmospheres, fire detection, fire suppression, and post-fire restoration.

Friedman, Robert↗