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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,477 records · Page 82
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Characterization of Tantalum Polymer Capacitors

Overview Reviewed data Caution must be taken when accelerating test conditions Data not useful to establish an acceleration model Introduction of new failure mechanism skewing results Evidence of Anti-Wear-Out De-doping of polymer Decreased capacitance Increased ESR Not dielectric breakdown Needs further investigation Further investigation into tantalum polymer capacitor technology Promising acceleration model for Manufacturer A Possibility for use in high-reliability space applications with suitable voltage derating.

Voltage Acceleration↗
NASA NTRS2010

Development of Constellation's Launch Control System

The paper focuses on the National Aeronautics and Space Administration (NASA) Constellation Program's Launch Control System (LCS) development effort at Kennedy Space Center (KSC). It provides a brief history of some preceding efforts to provide launch control and ground processing systems for other NASA programs, and some lessons learned from those experiences. It then provides high level descriptions of the LCS mission, objectives, organization, architecture, and progress. It discusses some of our development tenets, including our use of standards based design and use of off-the-shelf products whenever possible, incremental development cycles, and highly reliable, available, and supportable enterprise class system servers. It concludes with some new lessons learned and our plans for the future.

Lougheed, Kirk D.↗
NASA NTRS2013

Distributed Engine Control Empirical/Analytical Verification Tools

NASA's vision for an intelligent engine will be realized with the development of a truly distributed control system featuring highly reliable, modular, and dependable components capable of both surviving the harsh engine operating environment and decentralized functionality. A set of control system verification tools was developed and applied to a C-MAPSS40K engine model, and metrics were established to assess the stability and performance of these control systems on the same platform. A software tool was developed that allows designers to assemble easily a distributed control system in software and immediately assess the overall impacts of the system on the target (simulated) platform, allowing control system designers to converge rapidly on acceptable architectures with consideration to all required hardware elements. The software developed in this program will be installed on a distributed hardware-in-the-loop (DHIL) simulation tool to assist NASA and the Distributed Engine Control Working Group (DECWG) in integrating DCS (distributed engine control systems) components onto existing and next-generation engines.The distributed engine control simulator blockset for MATLAB/Simulink and hardware simulator provides the capability to simulate virtual subcomponents, as well as swap actual subcomponents for hardware-in-the-loop (HIL) analysis. Subcomponents can be the communication network, smart sensor or actuator nodes, or a centralized control system. The distributed engine control blockset for MATLAB/Simulink is a software development tool. The software includes an engine simulation, a communication network simulation, control algorithms, and analysis algorithms set up in a modular environment for rapid simulation of different network architectures; the hardware consists of an embedded device running parts of the CMAPSS engine simulator and controlled through Simulink. The distributed engine control simulation, evaluation, and analysis technology provides unique capabilities to study the effects of a given change to the control system in the context of the distributed paradigm. The simulation tool can support treatment of all components within the control system, both virtual and real; these include communication data network, smart sensor and actuator nodes, centralized control system (FADEC full authority digital engine control), and the aircraft engine itself. The DECsim tool can allow simulation-based prototyping of control laws, control architectures, and decentralization strategies before hardware is integrated into the system. With the configuration specified, the simulator allows a variety of key factors to be systematically assessed. Such factors include control system performance, reliability, weight, and bandwidth utilization.

DeCastro, Jonathan↗
NASA NTRS2013

Autonomous Cryogenic Leak Detector for Improving Launch Site Operations

NASA, military, and commercial satellite users need launch services that are highly reliable, less complex, easier to test, and cost effective. This project has developed a tapered optical fiber sensor for detecting hydrogen. The invention involves incorporating chemical indicators on the tapered end of an optical fiber using organically modified silicate nanomaterials. The Hazardous Gas Detection Lab (HGDL) at Kennedy Space Center is involved in the design and development of instrumentation that can detect and qualify various mission-critical chemicals. Historically, hydrogen, helium, nitrogen, oxygen, and argon are the first five gases of HGDL focus. The use of these cryogenic fluids in the area of propulsion offers challenges. Due to their extreme low temperatures, these fluids induce contraction of the materials they contact, a potential cause of leakage. Among them, hydrogen is of particular concern. Small sensors are needed in multiple locations without adding to the structural weight. The most vulnerable parts of the engine are the connection flanges on the transfer lines, which have to support cycles of large thermal amplitude. The thermal protection of the engine provides a closed area, increasing the likelihood of an explosive atmosphere. Thus, even a small leak represents an unacceptable hazardous condition during loading operations, in flight, or after an aborted launch. Tapered fibers were first fabricated from 1/1.3-mm core/cladding (silica/ plastic) optical fibers. Typically a 1-ft (approx. 30- cm) section of the 1-mm fiber is cut from the bundle and marked with a pen into five 2-.-in. (.5.7-cm) sections. A propane torch is applied at every alternate mark to burn the jacket and soften the glass core. While the core is softening, the two ends of the fiber are pulled apart slowly to create fine tapers of .- to .-in. (.6- to 12-mm) long on the 1-mm optical fiber. Following this, the non-tapered ends of the fibers are polished to a 0.3-micron finish. Then these fibers were coated with indicators sensitive to hydrogen. The tapered hydrogen detection system with its unique flexibility is the only system that can be placed in many locations inside the vehicles and detect the exact location of leaks, saving millions of dollars for launch vehicle industries.

Goswami, Kisholoy↗
NASA NTRS2013

Applications of Automation Methods for Nonlinear Fracture Test Analysis

As fracture mechanics material testing evolves, the governing test standards continue to be refined to better reflect the latest understanding of the physics of the fracture processes involved. The traditional format of ASTM fracture testing standards, utilizing equations expressed directly in the text of the standard to assess the experimental result, is self-limiting in the complexity that can be reasonably captured. The use of automated analysis techniques to draw upon a rich, detailed solution database for assessing fracture mechanics tests provides a foundation for a new approach to testing standards that enables routine users to obtain highly reliable assessments of tests involving complex, non-linear fracture behavior. Herein, the case for automating the analysis of tests of surface cracks in tension in the elastic-plastic regime is utilized as an example of how such a database can be generated and implemented for use in the ASTM standards framework. The presented approach forms a bridge between the equation-based fracture testing standards of today and the next generation of standards solving complex problems through analysis automation.

Allen, Phillip A.↗
NASA NTRS2013

Multi-Mission Earth Vehicle Subsonic Dynamic Stability Testing and Analyses

Multi-Mission Earth Entry Vehicles (MMEEVs) are blunt-body vehicles designed with the purpose of transporting payloads from outer space to the surface of the Earth. To achieve high-reliability and minimum weight, MMEEVs avoid use of limited-reliability systems, such as parachutes, retro-rockets, and reaction control systems and rely on the natural aerodynamic stability of the vehicle throughout the Entry, Descent, and Landing (EDL) phase of flight. The Multi-Mission Systems Analysis for Planetary Entry (M-SAPE) parametric design tool is used to facilitate the design of MMEEVs for an array of missions and develop and visualize the trade space. Testing in NASA Langley?s Vertical Spin Tunnel (VST) was conducted to significantly improve M-SAPE?s subsonic aerodynamic models. Vehicle size and shape can be driven by entry flight path angle and speed, thermal protection system performance, terminal velocity limitations, payload mass and density, among other design parameters. The objectives of the VST testing were to define usable subsonic center of gravity limits, and aerodynamic parameters for 6-degree-of-freedom (6-DOF) simulations, for a range of MMEEV designs. The range of MMEEVs tested was from 1.8m down to 1.2m diameter. A backshell extender provided the ability to test a design with a much larger payload for the 1.2m MMEEV.

Glaab, Louis J.↗
NASA NTRS2013

Impact Foam Testing for Multi-Mission Earth Entry Vehicle Applications

Multi-Mission Earth Entry Vehicles (MMEEVs) are blunt-body vehicles designed with the purpose of transporting payloads from outer space to the surface of the Earth. To achieve high-reliability and minimum weight, MMEEVs avoid use of limited-reliability systems, such as parachutes and retro-rockets, instead using built-in impact attenuators to absorb energy remaining at impact to meet landing loads requirements. The Multi-Mission Systems Analysis for Planetary Entry (M-SAPE) parametric design tool is used to facilitate the design of MMEEVs and develop the trade space. Testing was conducted to characterize the material properties of several candidate impact foam attenuators to enhance M-SAPE analysis. In the current effort, two different Rohacell foams were tested to determine their thermal conductivity in support of MMEEV design applications. These applications include thermal insulation during atmospheric entry, impact attenuation, and post-impact thermal insulation in support of thermal soak analysis. Results indicate that for these closed-cell foams, the effect of impact is limited on thermal conductivity due to the venting of the virgin material gas and subsequent ambient air replacement. Results also indicate that the effect of foam temperature is significant compared to data suggested by manufacturer's specifications.

Glaab, Louis J.↗
NASA NTRS2013

Quasi-Linear Circuit

This work involved developing spacequalifiable switch mode DC/DC power supplies that improve performance with fewer components, and result in elimination of digital components and reduction in magnetics. This design is for missions where systems may be operating under extreme conditions, especially at elevated temperature levels from 200 to 300 degC. Prior art for radiation-tolerant DC/DC converters has been accomplished utilizing classical magnetic-based switch mode converter topologies; however, this requires specific shielding and component de-rating to meet the high-reliability specifications. It requires complex measurement and feedback components, and will not enable automatic re-optimization for larger changes in voltage supply or electrical loading condition. The innovation is a switch mode DC/DC power supply that eliminates the need for processors and most magnetics. It can provide a well-regulated voltage supply with a gain of 1:100 step-up to 8:1 step down, tolerating an up to 30% fluctuation of the voltage supply parameters. The circuit incorporates a ceramic core transformer in a manner that enables it to provide a well-regulated voltage output without use of any processor components or magnetic transformers. The circuit adjusts its internal parameters to re-optimize its performance for changes in supply voltage, environmental conditions, or electrical loading at the output

Bradley, William↗
NASA NTRS2013

Environmentally-driven Materials Obsolescence: Material Replacements and Lessons Learned from NASA's Space Shuttle Program

The Space Shuttle Program was terminated in 2011 with the last flight of the Shuttle Endeavour. During the 30 years of its operating history, the number of domestic and international environmental regulations increased rapidly and resulted in materials obsolescence risks to the program. Initial replacement efforts focused on ozone depleting substances. As pressure from environmental regulations increased, Shuttle worked on the replacement of heavy metals. volatile organic compounds and hazardous air pollutants. Near the end of the program. Shuttle identified potential material obsolescence driven by international regulations and the potential for suppliers to reformulate materials. During the Shuttle Program a team focused on environmentally-driven materials obsolescence worked to identify and mitigate these risks. Lessons learned from the Shuttle experience can be applied to new NASA Programs as well as other high reliability applications.

Meinhold, Anne↗
NASA NTRS2013

Management of the Atmosphere Resource Recovery and Environmental Monitoring Project

The Advanced Exploration Systems Program's Atmosphere Resource Recovery and Environmental Monitoring (ARREM) project is working to further optimize atmosphere revitalization and environmental monitoring system architectures. This paper discusses project management strategies that tap into skill sets across multiple engineering disciplines, projects, field centers, and industry to achieve the project success. It is the project's objective to contribute to system advances that will enable sustained exploration missions beyond Lower Earth Orbit (LEO) and improve affordability by focusing on the primary goals of achieving high reliability, improving efficiency, and reducing dependence on ground-based logistics resupply. Technology demonstrations are achieved by infusing new technologies and concepts with existing developmental hardware and operating in a controlled environment simulating various crewed habitat scenarios. The ARREM project's strengths include access to a vast array of existing developmental hardware that perform all the vital atmosphere revitalization functions, exceptional test facilities to fully evaluate system performance, and a well-coordinated partnering effort among the NASA field centers and industry partners to provide the innovative expertise necessary to succeed.

Roman, Monsi↗
NASA NTRS2014

Solid-State Thermionic Nuclear Power for Megawatt Propulsion, Planetary Surface and Commercial Power Project

Thermionic (TI) power conversion is a promising technology first investigated for power conversion in the 1960's, and of renewed interest due to modern advances in nanotechnology, MEMS, materials and manufacturing. Benefits include high conversion efficiency (20%), static operation with no moving parts and potential for high reliability, greatly reduced plant complexity, and the potential for reduced development costs. Thermionic emission, credited to Edison in 1880, forms the basis of vacuum tubes and much of 20th century electronics. Heat can be converted into electricity when electrons emitted from a hot surface are collected across a small gap. For example, two "small" (6 kWe) Thermionic Space Reactors were flown by the USSR in 1987-88 for ocean radar reconnaissance. Higher powered Nuclear-Thermionic power systems driving Electric Propulsion (Q-thruster, VASIMR, etc.) may offer the breakthrough necessary for human Mars missions of < 1 yr round trip. Power generation on Earth could benefit from simpler, moe economical nuclear plants, and "topping" of more fuel and emission efficient fossil-fuel plants.

George, Jeffrey↗
NASA NTRS2014

Humidity Testing of PME and BME Ceramic Capacitors with Cracks

Cracks in ceramic capacitors are one of the major causes of failures during operation of electronic systems. Humidity testing has been successfully used for many years to verify the absence of cracks and assure quality of military grade capacitors. Traditionally, only precious metal electrode (PME) capacitors were used in high reliability applications and the existing requirements for humidity testing were developed for this type of parts. With the advance of base metal electrode (BME) capacitors, there is a need for assessment of the applicability of the existing techniques for the new technology capacitors. In this work, variety of different PME and BME capacitors with introduced cracks were tested in humid environments at different voltages and temperatures. Analysis of the test results indicates differences in the behavior and failure mechanisms for BME and PME capacitors and the need for different testing conditions.

reliability↗
NASA NTRS2014

Testing of a Neon Loop Heat Pipe for Large Area Cryocooling

Cryocooling of large areas such as optics, detector arrays, and cryogenic propellant tanks is required for future NASA missions. A cryogenic loop heat pipe (CLHP) can provide a closed-loop cooling system for this purpose and has many advantages over other devices in terms of reduced mass, reduced vibration, high reliability, and long life. A neon CLHP was tested extensively in a thermal vacuum chamber using a cryopump as the heat sink to characterize its transient and steady performance and verify its ability to cool large areas or components. Tests conducted included loop cool-down from the ambient temperature, startup, power cycle, heat removal capability, loop capillary limit and recovery from a dry-out, low power operation, and long duration steady state operation. The neon CLHP demonstrated robust operation. The loop could be cooled from the ambient temperature to subcritical temperatures very effectively, and could start successfully by applying power to both the pump and evaporator without any pre-conditioning. It could adapt to changes in the pump power andor evaporator power, and reach a new steady state very quickly. The evaporator could remove heat loads between 0.25W and 4W. When the pump capillary limit was exceeded, the loop could resume its normal function by reducing the pump power. Steady state operations were demonstrated for up to 6 hours. The ability of the neon loop to cool large areas was therefore successfully verified.

Cryogenics↗
NASA NTRS2014

Assessing Spectrum Compatibility for Beyond-Line-of-Sight UAS Control and Non-Payload Communications

In order to provide for the safe integration of unmanned aircraft systems (UAS) into the National Airspace System (NAS), the control and non-payload communications (CNPC) link must be highly reliable. A specific requirement is that it must operate using aviation safety radiofrequency spectrum. Two types of links are required - line-of-sight (LOS) using terrestrial-based communications and beyond-line- of-sight (BLOS) using satellite communications. The 2012 World Radiocommunication Conference (WRC-12) provided a suitable allocation for LOS CNPC spectrum in the 5030-5091 MHz band which, when combined with a previously existing allocation fulfills the LOS spectrum requirement. The 5030- 5091 MHz band is also allocated for BLOS CNPC, but since a significant portion of that band is required for LOS CNPC, additional BLOS spectrum is required. More critically, there are no satellites in operation or in development to provide such services in that band. Hence BLOS CNPC cannot be provided in protected aviation spectrum under current conditions. To fill this gap and enable integration of UAS into the NAS, it has been proposed to allow CNPC to operate over certain Fixed Satellite Service (FSS) bands in which many satellites currently provide commercial services. To enable this, changes in international regulation must be enacted. Agenda Item 1.5 of the 2015 WRC examines the possible regulatory changes needed. As part of the examination process, sharing between potential UAS using satellite communications for BLOS CNPC and other services allocated to the FSS bands being considered must be studied. This paper reviews the technical requirements and approach being undertaken for these sharing studies, with emphasis on study of interference from UAS into digital repeater links operating under the Fixed Service allocation. These studies are being conducted by NASA Glenn Research Center.

compatibility↗
NASA NTRS2013

BOK-Printed Electronics

The use of printed electronics technologies (PETs), 2D or 3D printing approaches either by conventional electronic fabrication or by rapid graphic printing of organic or nonorganic electronic devices on various small or large rigid or flexible substrates, is projected to grow exponentially in commercial industry. This has provided an opportunity to determine whether or not PETs could be applicable for low volume and high-reliability applications. This report presents a summary of literature surveyed and provides a body of knowledge (BOK) gathered on the current status of organic and printed electronics technologies. It reviews three key industry roadmaps- on this subject-OE-A, ITRS, and iNEMI-each with a different name identification for this emerging technology. This followed by a brief review of the status of the industry on standard development for this technology, including IEEE and IPC specifications. The report concludes with key technologies and applications and provides a technology hierarchy similar to those of conventional microelectronics for electronics packaging. Understanding key technology roadmaps, parameters, and applications is important when judicially selecting and narrowing the follow-up of new and emerging applicable technologies for evaluation, as well as the low risk insertion of organic, large area, and printed electronics.

Ghaffarian, Reza↗
NASA NTRS2014

Vertical Spin Tunnel Testing and Stability Analysis of Multi-Mission Earth Entry Vehicles

Multi-Mission Earth Entry Vehicles (MMEEVs) are blunt-body vehicles designed with the purpose of transporting payloads from space to the surface of the Earth. To achieve high reliability and minimum weight, MMEEVs avoid using limited-reliability systems, such as parachutes, retro-rockets, and reaction control systems and rely on the natural aerodynamic stability of the vehicle throughout the Entry, Descent, and Landing phases of flight. Testing in NASA Langley's 20-FT Vertical Spin Tunnel (20-FT VST), dynamically-scaled MMEEV models was conducted to improve subsonic aerodynamic models and validate stability criteria for this class of vehicle. This report documents the resulting data from VST testing for an array of 60-deg sphere-cone MMEEVs. Model configurations included were 1.2 meter, and 1.8 meter designs. The addition of a backshell extender, which provided a 150% increase in backshell diameter for the 1.2 meter design, provided a third test configuration. Center of Gravity limits were established for all MMEEV configurations. An application of System Identification (SID) techniques was performed to determine the aerodynamic coefficients in order to provide databases for subsequent 6-degree-of-freedom simulations.

Glaab, Louis J.↗
NASA NTRS2014

James Webb Space Telescope (JWST) Integrated Science Instruments Module (ISIM) Cryo-Vacuum (CV) Test at GSFC

JWST ISIM has entered into its system-level testing program at NASA Goddard Space Flight Center (GSFC). In December 2013, ISIM successfully completed the first in a series of three cryo-vacuum tests, which included two flight science instruments. Since then, there have been full-fledged efforts towards the CV2 test scheduled to finish at the end of 2014. The complexity of the mission has generated challenging requirements that demand highly reliable system performance and capabilities from the Space Environment Simulator (SES) vacuum chamber. In order to satisfy the program requirements, GSFC had to develop unique structural and thermal hardware to test ISIM. Most noteworthy is a helium shroud structure and cooling system built in order to achieve operational temperatures below 20K (-253C). This paper: (1) provides an overview of the integrated mechanical and thermal facility systems required to achieve the objectives of JWST ISIM testing, (2) communicates the performance and challenges of the SES during the first ISIM test, and (3) summarizes the action plan to improve the system prior to the next test.

Thermal Vacuum Cryo Testing Chamber↗
NASA NTRS2014

Assessing Spectrum Compatibility for Beyond-Line-of-Sight UAS Control and Non-Payload Communications

In order to provide for the safe integration of unmanned aircraft systems (UAS) into the National Airspace System (NAS), the control and non-payload communications (CNPC) link must be highly reliable. A specific requirement is that it must operate using aviation safety radiofrequency spectrum. Two types of links are required - line-of-sight (LOS) using terrestrial-based communications and beyond-line-of-sight (BLOS) using satellite communications. The 2012 World Radiocommunication Conference (WRC-12) provided a suitable allocation for LOS CNPC spectrum in the 5030 to 5091 MHz band which, when combined with a previously existing allocation fulfills the LOS spectrum requirement. The 5030 to 5091 MHz band is also allocated for BLOS CNPC, but since a significant portion of that band is required for LOS CNPC, additional BLOS spectrum is required. More critically, there are no satellites in operation or in development to provide such services in that band. Hence BLOS CNPC cannot be provided in protected aviation spectrum under current conditions. To fill this gap and enable integration of UAS into the NAS, it has been proposed to allow CNPC to operate over certain Fixed Satellite Service (FSS) bands in which many satellites currently provide commercial services. To enable this, changes in international regulation must be enacted. Agenda Item 1.5 of the 2015 WRC examines the possible regulatory changes needed. As part of the examination process, sharing between potential UAS using satellite communications for BLOS CNPC and other services allocated to the FSS bands being considered must be studied. This paper reviews the technical requirements and approach being undertaken for these sharing studies, with emphasis on study of interference from UAS into digital repeater links operating under the Fixed Service allocation. These studies are being conducted by NASA Glenn Research Center.

superhigh frequencies↗