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At least 199 records · Page 11

Concept Demonstration of Dopant Selective Reactive Etching (DSRIE) in Silicon Carbide

Accurate quantification of combustor pressure dynamics for the primary purpose of experimental validation of computational fluid dynamics (CFD) codes requires the use of robust, reliable and sensitive pressure sensors that can resolve sub--pound-per-square-inch pressure levels in high temperature environments (i.e., combustor). The state of the art microfabricated piezoresistive silicon carbide (SiC) pressure sensors that we have developed are capable of operating reliably at 600 degrees Centigrade. This technology was used in support of the ARMD ISRP-ERA (NASA's Aeronautics Research Mission Directorate, Integrated System Research Project - Environmentally Responsible Aviation) program to quantify combustor thermoacoustic instabilities. The results showed that while the SiC pressure sensors survived the high temperature and measured instabilities, the diaphragm (force collector) was not thin enough to be sensitive in resolving sub-pound-per-square-inch pressures; 30 meters is the thinnest diaphragm achievable with conventional reactive ion etching (RIE) processes. Therefore, this precludes its use for sub-pound-per-square-inch pressure measurement with high fidelity. In order to effectively resolve sub-pound-per-square-inch pressures, a thinner more sensitive diaphragm (10 meters) is needed. To achieve this would require a new and innovative fabrication process technique.

static

Analysis of transistor and snubber turn-off dynamics in high-frequency high-voltage high-power converters

Dc to dc converters which operate reliably and efficiently at switching frequencies high enough to effect substantial reductions in the size and weight of converter energy storage elements are studied. A two winding current or voltage stepup (buck boost) dc-to-dc converter power stage submodule designed to operate in the 2.5-kW range, with an input voltage range of 110 to 180 V dc, and an output voltage of 250 V dc is emphasized. In order to assess the limitations of present day component and circuit technologies, a design goal switching frequency of 10 kHz was maintained. The converter design requirements represent a unique combination of high frequency, high voltage, and high power operation. The turn off dynamics of the primary circuit power switching transistor and its associated turn off snubber circuitry are investigated.

Wilson, P. M.

DRIRU I/SKIRU - The application of the DTG to spacecraft attitude control

The dynamically tuned gyro (DTG) was developed to replace the floated, rate integrating gyro used for space attitude control, as the DTG fulfills cost, performance, and reliability requirements not satisfied by its predecessor. The use of this gyro in the Dry Gyro Inertial Reference Unit I (DRIRU I) marked the first application of a DTG in a spacecraft attitude reference unit. Design and performance characteristics of DTG application in the Singer-Kearfott Inertial Reference Unit (SKIRU) are outlined, for example its minimal weight (7 lb), and operational reliability. The DTG has accomplished 156,000 failure-free hours, and a chart, logging test performance, indicates that this and other requirements were more than sufficiently satisfied. The unit has an unparalleled life span, with several units still operating after 70,000 to 130,000 hours, and a random drift which always remains under 0.0005 deg/h. Potential for improvements, such as drift performance, are considered.

Swanson, C. O.

Enhancing 300 Degree Celsius Electronic Packaging with Ceramic PCBs and Advanced Interconnection Techniques

Geothermal energy development requires downhole tools that operate reliably at temperatures up to 320 °C. While MWD tools work without thermal protection and logging tools use vacuum flasks for limited high-temperature use, Sandia National Laboratories is developing durable electronics on ceramic PCBs with protective coatings to enable long-term operation of geothermal instruments at sustained temperatures up to 300 °C.

Wright, Andrew Alexander [Sandia National Laborato

Ares I Crew Launch Vehicle Project: Forward Plan to Preliminary Design Review

The Exploration Launch Projects Office, located at NASA's Marshall Space Flight Center, conducted the Ares I Crew Launch Vehicle System Requirements Review (SRR) at the end of 2006, a mere year after the project team was assembled. In Ares' first year, extensive trade studies and evaluations were conducted to refine the design initially recommended by the Exploration Systems Architecture Study, conceptual designs were analyzed for fitness, and the contractual framework was assembled to enable a development effort unparalleled in American space flight since the Space Shuttle. Now, the project turns its focus to the Preliminary Design Review (PDR), scheduled for 2008. Taking into consideration the findings of the SRR, the design of the Ares I is being tightened and refined to meet the operability, reliability, and affordability goals outlined by the Constellation Program. As directed in NASA Procedure and Regulation (NPR) 7123, NASA Systems Engineering Procedural Requirements, the Ares I SRR examined "the functional and performance requirements defined for the system and the preliminary program or project plan and ensures that the requirements and the selected concept will satisfy the mission." The SRR was conducted to ensure the system- and element-level design and interface requirements are defined prior to proceeding into the project's design phase. The Exploration Launch Projects Control Board convened on December 19,2006, and accepted the findings of the SRR and the go-forward plan proceeding to PDR. Based upon these findings, the Ares project believes that operability must drive the vehicle's design, and that a number of design challenges, including system mass and reliability, must be addressed as part of the progress to PDR.

Dumbacher, Daniel L.

Parts Quality Management: Direct Part Marking via Data Matrix Symbols for Mission Assurance

A United States Government Accountability Office (GAO) review of twelve NASA programs found widespread parts quality problems contributing to significant cost overruns, schedule delays, and reduced system reliability. Direct part-marking with Data Matrix symbols could significantly improve the quality of inventory control and parts lifecycle management. This paper examines the feasibility of using 15 marking technologies for use in future NASA programs. A structural analysis is based on marked material type, operational environment (e.g., ground, suborbital, orbital), durability of marks, ease of operation, reliability, and affordability. A cost-benefits analysis considers marking technology (data plates, label printing, direct part marking) and marking types (two-dimensional machine-readable, human-readable). Previous NASA parts marking efforts and historical cost data are accounted for, including in-house vs. outsourced marking. Some marking methods are still under development. While this paper focuses on NASA programs, results may be applicable to a variety of industrial environments.

Moss, Chantrice

Parts Quality Management: Direct Part Marking of Data Matrix Symbol for Mission Assurance

A United States Government Accountability Office (GAO) review of twelve NASA programs found widespread parts quality problems contributing to significant cost overruns, schedule delays, and reduced system reliability. Direct part marking with Data Matrix symbols could significantly improve the quality of inventory control and parts lifecycle management. This paper examines the feasibility of using direct part marking technologies for use in future NASA programs. A structural analysis is based on marked material type, operational environment (e.g., ground, suborbital, Low Earth Orbit), durability of marks, ease of operation, reliability, and affordability. A cost-benefits analysis considers marking technology (label printing, data plates, and direct part marking) and marking types (two-dimensional machine-readable, human-readable). Previous NASA parts marking efforts and historical cost data are accounted for, including inhouse vs. outsourced marking. Some marking methods are still under development. While this paper focuses on NASA programs, results may be applicable to a variety of industrial environments.

Moss, Chantrice

Atmospheric contaminant sensor, book 1

Design and fabrication of a mass spectrometer system for use as an atmospheric monitor by submarine is reported. The performance design goals are presented. The operation of the system is essentially automatic, providing continuous display of the partial pressures of the principal atmospheric constituents and a pushbutton update display of two freon trace contaminants. The freon update cycle takes 15 or 30 seconds, depending on which are measured. Trouble free, long term, reliable operation, and ease of maintenance are the primary system requirements. The requirement of the freon detection with high sensitivity and high resolution made redesign of the overall analyzer housing and magnet necessary.

Scott, B. W.

Ares Launch Vehicles Overview: Space Access Society

America is returning to the Moon in preparation for the first human footprint on Mars, guided by the U.S. Vision for Space Exploration. This presentation will discuss NASA's mission, the reasons for returning to the Moon and going to Mars, and how NASA will accomplish that mission in ways that promote leadership in space and economic expansion on the new frontier. The primary goals of the Vision for Space Exploration are to finish the International Space Station, retire the Space Shuttle, and build the new spacecraft needed to return people to the Moon and go to Mars. The Vision commits NASA and the nation to an agenda of exploration that also includes robotic exploration and technology development, while building on lessons learned over 50 years of hard-won experience. NASA is building on common hardware, shared knowledge, and unique experience derived from the Apollo Saturn, Space Shuttle, and contemporary commercial launch vehicle programs. The journeys to the Moon and Mars will require a variety of vehicles, including the Ares I Crew Launch Vehicle, which transports the Orion Crew Exploration Vehicle, and the Ares V Cargo Launch Vehicle, which transports the Lunar Surface Access Module. The architecture for the lunar missions will use one launch to ferry the crew into orbit, where it will rendezvous with the Lunar Module in the Earth Departure Stage, which will then propel the combination into lunar orbit. The imperative to explore space with the combination of astronauts and robots will be the impetus for inventions such as solar power and water and waste recycling. This next chapter in NASA's history promises to write the next chapter in American history, as well. It will require this nation to provide the talent to develop tools, machines, materials, processes, technologies, and capabilities that can benefit nearly all aspects of life on Earth. Roles and responsibilities are shared between a nationwide Government and industry team. The Exploration Launch Projects Office at the Marshall Space Flight Center manages the design, development, testing, and evaluation of both vehicles and serves as lead systems integrator. A little over a year after it was chartered, the Exploration Launch Projects team is testing engine components, refining vehicle designs, performing wind tunnel tests, and building hardware for the first flight test of Ares I-X, scheduled for spring 2009. The Exploration Launch Projects team conducted the Ares I System Requirements Review (SRR) at the end of 2006. In Ares' first year, extensive trade studies and evaluations were conducted to refine the design initially recommended by the Exploration Systems Architecture Study, conceptual designs were analyzed for fitness, and the contractual framework was assembled to enable a development effort unparalleled in American space flight since the Space Shuttle. Now, the project turns its focus to the Preliminary Design Review (PDR), scheduled for 2008. Taking into consideration the findings of the SRR, the design of the Ares I is being tightened and refined to meet the safety, operability, reliability, and affordability goals outlined by the Constellation Program. The Ares V is in the early design stage, focusing its activities on requirements validation and ways to develop this heavy-lift system so that synergistic hardware commonality between it and the Ares I can reduce the operational footprint and foster sustained exploration across the decades ahead.

Cook, Steve

Phasing COTS Part Into Low-Risk-Tolerant Missions

A number of activities within NASA and the space community, as well as growing technology needs and supply chain changes have accelerated the need to expand the use of COTS parts within NASA. While the use of COTS has been formally institutionalized and deemed acceptable for Class D space missions and those with greater tolerance for risk, there is still a lack of understanding of how to most effectively use COTS in such high risk-tolerance missions, and no apparent path towards broad use in missions with much less tolerance for risk. However, the reality is that the fundamental limitations of technology associated with the military specification system combined with the need to fly newer technologies in upcoming flagship robotic missions and human space flight missions will ultimately demand a more expansive use of COTS. The infinite nature of COTS gives rise to numerous challenges in the selection, acceptance, testing, and usage of COTS when reliable operation is essential. This presentation will highlight some of the results of a NASA Engineering and Safety Center (NESC) study on the use of COTS parts, as well as many of the historical through current facts about parts assurance within Agency to provide a path forward for reliable use of COTS for a range of space applications and risk postures. In addition this presentation will dispel the myth that expanded use of COTS parts causes a new set of radiation threats to missions.

COTS

Phasing COTS Part Into Low-Risk-Tolerant Missions

A number of activities within NASA and the space community, as well as growing technology needs and supply chain changes have accelerated the need to expand the use of COTS parts within NASA. While the use of COTS has been formally institutionalized and deemed acceptable for Class D space missions and those with greater tolerance for risk, there is still a lack of understanding of how to most effectively use COTS in such high risk-tolerance missions, and no apparent path towards broad use in missions with much less tolerance for risk. However, the reality is that the fundamental limitations of technology associated with the military specification system combined with the need to fly newer technologies in upcoming flagship robotic missions and human space flight missions will ultimately demand a more expansive use of COTS. The infinite nature of COTS gives rise to numerous challenges in the selection, acceptance, testing, and usage of COTS when reliable operation is essential. This presentation will highlight some of the results of a NASA Engineering and Safety Center (NESC) study on the use of COTS parts, as well as many of the historical through current facts about parts assurance within Agency to provide a path forward for reliable use of COTS for a range of space applications and risk postures. In addition this presentation will dispel the myth that expanded use of COTS parts causes a new set of radiation threats to missions.

COTS

A Near-Term, High-Confidence Heavy Lift Launch Vehicle

The use of well understood, legacy elements of the Space Shuttle system could yield a near-term, high-confidence Heavy Lift Launch Vehicle that offers significant performance, reliability, schedule, risk, cost, and work force transition benefits. A side-mount Shuttle-Derived Vehicle (SDV) concept has been defined that has major improvements over previous Shuttle-C concepts. This SDV is shown to carry crew plus large logistics payloads to the ISS, support an operationally efficient and cost effective program of lunar exploration, and offer the potential to support commercial launch operations. This paper provides the latest data and estimates on the configurations, performance, concept of operations, reliability and safety, development schedule, risks, costs, and work force transition opportunities for this optimized side-mount SDV concept. The results presented in this paper have been based on established models and fully validated analysis tools used by the Space Shuttle Program, and are consistent with similar analysis tools commonly used throughout the aerospace industry. While these results serve as a factual basis for comparisons with other launch system architectures, no such comparisons are presented in this paper. The authors welcome comparisons between this optimized SDV and other Heavy Lift Launch Vehicle concepts.

Rothschild, William J.

Phasing in COTS EEE parts in NASA

A number of activities within NASA and the space community, as well as growing technology needs and supply chain changes have accelerated the need to expand the use of COTS parts within NASA. While the use of COTS has been formally institutionalized and deemed acceptable for Class D space missions and those with greater tolerance for risk, there is still a lack of understanding of how to most effectively use COTS in such high risk-tolerance missions, and no apparent path towards broad use in missions with much less tolerance for risk. However, the reality is that the fundamental limitations of technology associated with the military specification system combined with the need to fly newer technologies in upcoming flagship robotic missions and human space flight missions will ultimately demand a more expansive use of COTS. The infinite nature of COTS gives rise to numerous challenges in the selection, acceptance, testing, and usage of COTS when reliable operation is essential. This presentation will highlight some of the current artifacts of a NASA Engineering and Safety Center (NESC) study on the use of COTS parts, as well as many of the historical through current facts about parts assurance within Agency to provide a path forward for reliable use of COTS for a range of space applications and risk postures.

EEE parts

The reusable Space Shuttle Main Engine prepares for long life

Attention is given to Space Shuttle Main Engine (SSME) life extension and logistical systems that support launch and ground operations. The operations and maintenance tasks involved in this aspect of SSME development include turnaround requirements, ground support equipment, and control documentation. A discussion is presented on the spare parts provisioning system, which emphasizes the source of decision-making data and encompasses the hardware tracking system, usage data from ground testing and launch operations, and current and projected life limits. The life extension test program leads the launch program, offering comfortable life limit margins. Planned overhauls for the extension of useful hardware life beyond the 55-mission requirement, a turnabout improvement program, and a continuous training program contribute to launch cost reductions, reliable operations, and long life.

Klatt, F. P., Jr.

Preliminary Aerodynamic Measurements from a Magnetic Suspension and Balance System in a Low-Speed Wind Tunnel

An existing Magnetic Suspension and Balance System (MSBS) has been restored to operation in a small (octagonal test section, 6-inches across flats) low-speed wind tunnel as the first phase of a project to develop new dynamic test capabilities for planetary entry capsules at supersonic speeds. The MSBS and associated wind tunnel were originally designed and built at MIT and were subsequently relocated to NASA Langley Research Center. NASA ceased operations of the system in the late 1990s and it was transferred to Old Dominion University where it had been mothballed until the present work started in 2015. All-new position sensor electronics, electromagnet power supplies, digital controller, and other hardware have been developed, leading to more efficient and reliable operation. Important features of the new hardware will be briefly described. Wind tunnel testing has commenced, focusing first on static aerodynamics of re-entry capsule shapes. Some preliminary results will be reviewed, including comparison to reference data. The proposed extension to dynamic stability testing, using a variety of free-to-pitch approaches will be described. Finally, the preliminary design of the all-new Phase II (supersonic) system will be briefly outlined.

Schoenenberger, Mark

Predictive Modeling and Operational Monitoring of Starlink Leo Satellite Network Performance in Maritime Environments

This thesis investigates short-term performance prediction for maritime LEO operational planning and application performance cannot anticipate available bandwidth or communication delay, which complicates variation alter signal conditions over short time scales. As a result, maritime users often fluctuations in link quality. In addition, Frequent satellite handoffs and Doppler-induced rapid satellite movement and changing atmospheric conditions cause substantial unavailable. Despite their availability, reliable operation at sea remains difficult because broadband connectivity in maritime regions where terrestrial infrastructure in

97 MATHEMATICS AND COMPUTING

Maintenance Modernization in the Era of Artemis An RCM Journey

The NASA Artemis Program mission to return humans to the moon requires it ground test facilities to meet today’s performance and throughput demands. The NASA Ames Arc Jet Complex (AJC) at Ames Research Center is the Agency’s sole ground test facility supporting reentry thermal protection system testing and was developed to support Apollo era spacecraft. The research and development required to meet current and future mission demands continually grows, but the maintenance upkeep to ensure safe and reliable operations holds stagnant. This paper presents the journey and subsequent industry relatable story that includes the challenges, lessons learned, and testimonials to the AJC’s approach to the modernization of maintenance using RCM at NASA.

Reliability Centered Maintenance

Real-time Simulation Model of a Vanadium Redox Flow Battery Energy Storage System with Power Electronics Integration

This paper presents a real-time (RT) model of a 20 kW multi-stack vanadium redox flow battery (VRFB) system including power electronics converters in a single real-time framework. Implemented on a Typhoon HIL 604 device, this model is designed to simulate the operation of the flow battery with system-level controls. To provide a realistic overview of a VRFB system, the model incorporates a closed-loop control system for managing the speeds of two centrifugal pumps and an electro-thermal model of the battery stacks, enabling realtime temperature estimation. Furthermore, a two-stage power electronics topology and associated control solution are presented, operating with distinct strategies for interfacing the battery model with the main grid and a local load. Results from simulations demonstrate that the VRFB model is well suited for RT environment, and system can manage power during both charging and discharging cycles, while a SCADA monitor is used to display critical variables for safe, efficient, and reliable operation of the VRFB systems.

Rezende Da Costa Reis Kimpara, Renata [ORNL] (ORCI