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  • 1
    Publication Date: 2019-11-27
    Description: Final document is attached. Status and preliminary results for the development of a large format fractional thermal runaway calorimeter (L-FTRC) capable of measuring the total energy release and fractional energy release for Li-ion cells that have greater than 100 Ah capacities.
    Keywords: Spacecraft Propulsion and Power
    Type: JSC-E-DAA-TN75665 , NASA Aerospace Battery Workshop; Nov 19, 2019 - Nov 21, 2019; Huntsville, AL; United States
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  • 2
    Publication Date: 2019-09-10
    Description: Uncertainty in erosion rates as measured by different methods is discussed and quantified. The work focuses on case studies from components on the Hall Effect Rocket with Magnetic Shielding (HERMeS) Hall thruster, but the methods can be extended for many electric propulsion applications. The primary method used for evaluating erosion is non-contact profilometry of masked and exposed components. Accurate quantification of the erosion rates of components is critical to determining lifetime and is therefore critical to mission planning purposes.
    Keywords: Spacecraft Propulsion and Power
    Type: GRC-E-DAA-TN70751 , AIAA Propulsion and Energy Forum and Exposition; Aug 19, 2019 - Aug 22, 2019; Indianapolis, IN; United States
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  • 3
    Publication Date: 2019-07-13
    Description: In support of the Double Asteroid Redirection Test (DART) mission, laboratory measurements were made on the NEXT ion engine, which will be used for the spacecraft's in-space propulsion [1]. This study revisits a small range of mission-specific 2.7A throttle levels to understand the effect of in-flight flow rate variability, investigate intermediate throttle conditions, and improve measurement methodology. This paper specifically examines the far-field plume divergence and backflow ion flux distribution of the NEXT, while a companion paper examines the charge state distributions.
    Keywords: Spacecraft Propulsion and Power
    Type: GRC-E-DAA-TN63682 , AIAA Science and Technology Forum and Exposition (SciTech); Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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  • 4
    Publication Date: 2019-07-19
    Description: Improving protection and health management capabilities onboard the electrical power system (EPS) for spacecraft is essential for ensuring safe and reliable conditions for deep space human exploration. Electrical protection and control technologies on the National Aeronautics and Space Administration's (NASA's) current human space platform relies heavily on ground support to monitor and diagnose power systems and failures. As communication bandwidth diminishes for deep space applications, a transformation in system monitoring and control becomes necessary to maintain high reliability of electric power service. This paper presents a novel approach for on-line power system security monitoring for autonomous deep space spacecraft.
    Keywords: Spacecraft Propulsion and Power
    Type: GRC-E-DAA-TN63587 , GRC-E-DAA-TN57847 , AIAA SciTech Forum 2019; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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  • 5
    Publication Date: 2019-07-20
    Description: Power production is a key aspect to any Mars mission. One method for providing power throughout the day/night cycle, or to satisfy short-duration high-output power needs, is to utilize a regenerative fuel cell system for providing energy storage and nighttime or supplemental power. This study compares the total system mass for two types of fuel cell systems, proton exchange membrane (PEM) and solid oxide (SO), sized to provide 10 kW of electrical output power in the Mars environment. Two operating locations were examined; one near the equator at 4 S latitude and one the higher northern latitude of 48N. The systems were sized to operate throughout the year at these locations, where the radiator was sized for the worst-case warm condition and the insulation was sized for the worst-case cold condition. Using the selected system parameters, the results for both latitudes showed that the lightest system was the SO fuel cell with a PEM electrolyzer. This was mainly due to the higher operational temperature of the SO system enabled a significantly smaller radiator mass compared to that of the PEM fuel cell system. However, there was a significant difference in mass for the PEM system when operated near the equator as compared to the higher northern latitude. For the 10-kW output system this difference in mass was just under 100 kg.
    Keywords: Spacecraft Propulsion and Power
    Type: GRC-E-DAA-TN62192 , NASA/TM-2019-220019
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  • 6
    Publication Date: 2019-11-26
    Description: With the National Aeronautics and Space Administration's (NASA) rising interest in lunar surface operations and deep space exploration, there is a growing need to move from traditional ground-based mission operations to more autonomous vehicle level operations. In lunar surface operations, there are periods of time where communications with ground-based mission control could not occur, forcing vehicles and a lunar base to completely operate independent of the ground. For deep space exploration missions, communication latency times increase to greater than 15 minutes making real-time control of critical systems difficult, if not near impossible. These challenges are driving the need for an autonomous power control system that has the capability to manage power and energy. This will ensure that critical loads have the necessary power to support life systems and carry out critical mission objectives. This paper presents a flexible, hierarchical, distributed control methodology that enables autonomous operation of smart grids and can integrate into a higher level autonomous architecture.
    Keywords: Spacecraft Propulsion and Power
    Type: IAC-19-C3.4.3 , GRC-E-DAA-TN73470 , International Astronautical Congress (IAC); Oct 21, 2019 - Oct 25, 2019; Washington, DC; United States
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  • 7
    Publication Date: 2019-07-20
    Description: A series of short-duration (200 h) wear tests were conducted with two Hall Effect Rocket with Magnetic Shielding (HERMeS) technology demonstration units. Front pole covers, cathode keeper, and discharge channel wear were characterized as a function of discharge voltage, magnetic field strength, and chamber pressure. No discharge channel erosion was observed. Inner pole cover erosion was shown to be a weak function of discharge voltage with most erosion occurring at the lowest value, 300 V. The Technology Demonstration Unit (TDU) 3 keeper electrode eroded with each operating condition, with high magnetic field yielding the greatest erosion rate. The TDU-1 keeper electrode exhibited net deposition suggesting its configuration is more consistent with meeting overall HERMeS service life requirements. Ratios of molybdenum to graphite erosion rates suggests, with high uncertainty, that the sputtering ions are originating downstream of the thruster exit plane, striking the surface with small angles of incidence.
    Keywords: Spacecraft Propulsion and Power
    Type: NASA/TM-2019-219731 , IEPC?2017?207 , E-19456 , GRC-E-DAA-TN48801 , International Electric Propulsion Conference; Oct 08, 2017 - Oct 12, 2017; Atlanta, GA; United States
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  • 8
    Publication Date: 2019-07-20
    Description: NASA space missions have long employed Radioisotope Power Systems (RPS) and solar-based power generation architectures. RPS have been used to enable or significantly enhance missions that venture deep into the solar system to distances from the sun which can make using solar architectures unfeasible and to areas where the sun is obscured due to shadows or atmospheric phenomena. The destination, however, is not the absolute factor of the determination of RPS or solar. This is highlighted by the Jupiter missions Galileo and Juno, which employed RPS and solar architectures, respectively. When baselining either RPS or solar architectures for a planetary mission, numerous factors must be considered, including scientific objectives, cost, schedule, and mass just to name a few. In an effort to better understand the decision-making process and provide insight for potential future missions, the NASA RPS Program Office tasked The Aerospace Corporation (Aerospace) to study historical missions that used RPS and solar architectures. Data was collected for a variety of RPS and solar missions to look for possible trends from the selected implementation. Additionally, mission case studies were developed based on interviews with mission personnel who were responsible for defining the power architecture of their mission. Informed by the data collected and case studies, two Measures of Effectiveness (MoEs) were produced: one based on cost of RPS versus solar, and one based on science mission cost effectiveness. The final results of this study have been captured in this briefing package which is available for full and open release. Additionally, a final report document also provides the same details of this package. This briefing package also includes an appendix which contains data not for public release which was used to provide detailed answers to questions raised during this study. The results of these inquiries are discussed in the report, but the proprietary data is not included. Finally, an executive summary package is also publicly available which was used to present the results of the study at the 2018 Aerospace Space Power Workshop.
    Keywords: Spacecraft Propulsion and Power
    Type: NASA/CR-2019-220039 , ATR-2018-02688 , GRC-E-DAA-TN62337
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  • 9
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    In:  CASI
    Publication Date: 2019-07-13
    Description: NASA's Evolutionary Xenon Thruster (NEXT) is ready for transition-to-flight. The thruster has completed all qualification-level environmental testing, and has demonstrated a xenon propellant throughput, total impulse, and total operating hours greatly in excess of anticipated planetary science mission requirements, and exceeding that achieved by any other thruster technology in the history of electric propulsion. NEXT is the next generation system, a natural progression in technology from that implemented successfully on the Deep-Space one and Dawn missions, developed at NASA's Glenn Research Center in Cleveland, Ohio. The first implementation of NEXT will be on NASA 's Double Asteroid Redirection Test (DART). DART will be the first demonstration of the kinetic impact technique to change the motion of an asteroid in space. The DART mission is in Phase C, led by Johns Hopkins University Applied Physics Laboratory. The DART spacecraft will utilize the NASA Evolutionary Xenon Thruster solar electric propulsion system as its primary in-space propulsion system. By utilizing NEXT, DART is able to gain significant flexibility to the mission timeline and launch window, as well as decrease in launch vehicle cost. This presentation will review NASA's investment strategy in electric propulsion _ in particular gridded ion thruster technology _ as it applies to solar system exploration. Results obtained from implementing this technology on Deep-Space one and Dawn will be reviewed. Mission studies which highlight the impacts of the NEXT technology will be discussed, and near-term proposed and scheduled missions including DART and CAESAR (Comet Astrobiology Exploration Sample Return) will be reviewed.
    Keywords: Spacecraft Propulsion and Power
    Type: GRC-E-DAA-TN66640 , American Chemical Society (ACS) National Meeting and Exposition; Mar 31, 2019 - Apr 04, 2019; Orlando, FL; United States
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  • 10
    Publication Date: 2019-08-27
    Description: Heaterless hollow cathodes provide an opportunity to reduce complexity and improve reliability in electric propulsion systems. While removal of the heater has little effect on steady-state operation of a hollow cathode, it has a considerable effect on the ignition process. To successfully integrate a heaterless hollow cathode into a spaceflight electric propulsion system, it will be necessary to establish definitive requirements for the propellant feed and electrical subsystems so that ignition of a plasma discharge can be achieved reliably. The aim of this research was to form a better understanding of these requirements by performing an investigation of the propellant flow and voltage conditions required for the ignition of a plasma arc discharge. This aim was achieved by performing discharge initiation experiments using both a specially designed experimental apparatus and a functional heaterless hollow cathode assembly. It was demonstrated that there is a distinct difference in the voltage required to initiate a plasma discharge between two common electric propulsion propellants, xenon and krypton, which suggests that the developmental testing of heaterless hollow cathodes needs to be performed with the appropriate propellant gas species. Heaterless hollow cathode ignition experiments showed that the keeper orifice diameter has a strong effect on the voltage required to ignite a plasma discharge at a given propellant mass flow rate, while the effect of keeper-cathode separation distance was only strong at flow rates below 25 sccm (Xe).
    Keywords: Spacecraft Propulsion and Power
    Type: GRC-E-DAA-TN70748 , AIAA Joint Propulsion Conference 2019; Aug 19, 2019 - Aug 22, 2019; Indianapolis, IN; United States
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