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  • 1
    Publication Date: 2019-07-13
    Description: The International Space Station program is developing a robotically-operated leak locator tool to be used externally. The tool would consist of a Residual Gas Analyzer for partial pressure measurements and a full range pressure gauge for total pressure measurements. The primary application is to detect NH3 coolant leaks in the ISS thermal control system.An analytical model of leak plume physics is presented that can account for effusive flow as well as plumes produced by sonic orifices and thruster operations. This model is used along with knowledge of typical RGA and full range gauge performance to analyze the expected instrument sensitivity to ISS leaks of various sizes and relative locations (directionality).The paper also presents experimental results of leak simulation testing in a large thermal vacuum chamber at NASA Goddard Space Flight Center. This test characterized instrument sensitivity as a function of leak rates ranging from 1 lbmyr. to about 1 lbmday. This data may represent the first measurements collected by an RGA or ion gauge system monitoring off-axis point sources as a function of location and orientation. Test results are compared to the analytical model and used to propose strategies for on-orbit leak location and environment characterization using the proposed instrument while taking into account local ISS conditions and the effects of ramwake flows and structural shadowing within low Earth orbit.
    Keywords: Spacecraft Design, Testing and Performance
    Type: GSFC-E-DAA-TN15807 , International Symposium on Rarefied Gas Dynamics; Jul 13, 2014 - Jul 18, 2014; Xian; China
    Format: application/pdf
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  • 2
    Publication Date: 2019-07-13
    Description: The International Space Station (ISS) and all currently conceivable future manned spacecraft are susceptible to mission impacts due to fluid/gas leaks to the exterior environment. For example, there is a well-known risk of ammonia leaks from the ISS External Active Thermal Control System (EATCS) loops and as of 2016 there was no method to locate them. It was, therefore, critical to develop a method for detecting and locating leaks to preserve vehicle health. The Robotic External Leak Locator (RELL) was developed and deployed to the ISS to provide this capability. An on-orbit validation and demonstration was successfully completed in December 2016 and leak locating operations occurred in February 2017. This paper discusses the results of these exercises including measurements of the environment around ISS, detection of a small ammonia leak and implementation of leak locating methodologies. RELL is a collaboration between NASA's Goddard Space Flight Center (GSFC) and Johnson Space Center (JSC) and was launched to the ISS as a Technology Demonstration Payload in December 2015 on Orbital-ATK Commercial Resupply Flight 4.
    Keywords: Space Transportation and Safety; Spacecraft Instrumentation and Astrionics
    Type: JSC-E-DAA-TN60198 , AIAA Space Forum 2018; Sep 17, 2018 - Sep 19, 2018; Orlando, FL; United States
    Format: application/pdf
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  • 3
    Publication Date: 2019-07-13
    Description: The International Space Station program is developing a robotically-operated leak locator tool to be used externally. The tool would consist of a Residual Gas Analyzer for partial pressure measurements and a full range pressure gauge for total pressure measurements. The primary application is to detect NH3 coolant leaks in the ISS thermal control system. An analytical model of leak plume physics is presented that can account for effusive flow as well as plumes produced by sonic orifices and thruster operations. This model is used along with knowledge of typical RGA and full range gauge performance to analyze the expected instrument sensitivity to ISS leaks of various sizes and relative locations ("directionality"). The paper also presents experimental results of leak simulation testing in a large thermal vacuum chamber at NASA Goddard Space Flight Center. This test characterized instrument sensitivity as a function of leak rates ranging from 1 lb-mass/yr. to about 1 lb-mass/day. This data may represent the first measurements collected by an RGA or ion gauge system monitoring off-axis point sources as a function of location and orientation. Test results are compared to the analytical model and used to propose strategies for on-orbit leak location and environment characterization using the proposed instrument while taking into account local ISS conditions and the effects of ram/wake flows and structural shadowing within low Earth orbit.
    Keywords: Cybernetics, Artificial Intelligence and Robotics; Spacecraft Instrumentation and Astrionics; Spacecraft Design, Testing and Performance
    Type: GSFC-E-DAA-TN15645 , International Symposium on Rarefied Gas Dynamics; Jul 13, 2014 - Jul 18, 2014; Xian; China
    Format: application/pdf
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  • 4
    Publication Date: 2019-08-26
    Description: A toilet for use on a space vehicle has a toilet bowl having a storage canister at a remote end for receiving human waste. The compactor includes a cable connected to a lever which pulls the cable in a direction forcing the compactor into the storage canister to compact the captured waste when the lever is actuated.
    Keywords: Man/System Technology and Life Support
    Format: application/pdf
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