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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Using graphics and expert system technologies to support satellite monitoring at the NASA Goddard Space Flight Center

At NASA's Goddard Space Flight Center, fault-isolation expert systems have been developed to support data monitoring and fault detection tasks in satellite control centers. Based on the lessons learned during these efforts in expert system automation, a new domain-specific expert system development tool named the Generic Spacecraft Analysts Assistant (GenSAA), was developed to facilitate the rapid development and reuse of real-time expert systems to serve as fault-isolation assistants for spacecraft analysts. This paper describes GenSAA's capabilities and how it is supporting monitoring functions of current and future NASA missions for a variety of satellite monitoring applications ranging from subsystem health and safety to spacecraft attitude. Finally, this paper addresses efforts to generalize GenSAA's data interface for more widespread usage throughout the space and commercial industry.

Hughes, Peter M.↗
NASA NTRS2004

Agent Architecture for Aviation Data Integration System

This paper describes the proposed agent-based architecture of the Aviation Data Integration System (ADIS). ADIS is a software system that provides integrated heterogeneous data to support aviation problem-solving activities. Examples of aviation problem-solving activities include engineering troubleshooting, incident and accident investigation, routine flight operations monitoring, safety assessment, maintenance procedure debugging, and training assessment. A wide variety of information is typically referenced when engaging in these activities. Some of this information includes flight recorder data, Automatic Terminal Information Service (ATIS) reports, Jeppesen charts, weather data, air traffic control information, safety reports, and runway visual range data. Such wide-ranging information cannot be found in any single unified information source. Therefore, this information must be actively collected, assembled, and presented in a manner that supports the users problem-solving activities. This information integration task is non-trivial and presents a variety of technical challenges. ADIS has been developed to do this task and it permits integration of weather, RVR, radar data, and Jeppesen charts with flight data. ADIS has been implemented and used by several airlines FOQA teams. The initial feedback from airlines is that such a system is very useful in FOQA analysis. Based on the feedback from the initial deployment, we are developing a new version of the system that would make further progress in achieving following goals of our project.

Kulkarni, Deepak↗
NASA NTRS2012

Physics Based Electrolytic Capacitor Degradation Models for Prognostic Studies under Thermal Overstress

Electrolytic capacitors are used in several applications ranging from power supplies on safety critical avionics equipment to power drivers for electro-mechanical actuators. This makes them good candidates for prognostics and health management research. Prognostics provides a way to assess remaining useful life of components or systems based on their current state of health and their anticipated future use and operational conditions. Past experiences show that capacitors tend to degrade and fail faster under high electrical and thermal stress conditions that they are often subjected to during operations. In this work, we study the effects of accelerated aging due to thermal stress on different sets of capacitors under different conditions. Our focus is on deriving first principles degradation models for thermal stress conditions. Data collected from simultaneous experiments are used to validate the desired models. Our overall goal is to derive accurate models of capacitor degradation, and use them to predict performance changes in DC-DC converters.

Kulkarni, Chetan S.↗
NASA NTRS2012

Bayesian Framework Approach for Prognostic Studies in Electrolytic Capacitor under Thermal Overstress Conditions

Electrolytic capacitors are used in several applications ranging from power supplies for safety critical avionics equipment to power drivers for electro-mechanical actuator. Past experiences show that capacitors tend to degrade and fail faster when subjected to high electrical or thermal stress conditions during operations. This makes them good candidates for prognostics and health management. Model-based prognostics captures system knowledge in the form of physics-based models of components in order to obtain accurate predictions of end of life based on their current state of heal th and their anticipated future use and operational conditions. The focus of this paper is on deriving first principles degradation models for thermal stress conditions and implementing Bayesian framework for making remaining useful life predictions. Data collected from simultaneous experiments are used to validate the models. Our overall goal is to derive accurate models of capacitor degradation, and use them to remaining useful life in DC-DC converters.

Kulkarni, Chetan S.↗
NASA NTRS2014

Lithium-Ion Electrolytes Containing Flame Retardant Additives for Increased Safety Characteristics

The invention discloses various embodiments of Li-ion electrolytes containing flame retardant additives that have delivered good performance over a wide temperature range, good cycle life characteristics, and improved safety characteristics, namely, reduced flammability. In one embodiment of the invention there is provided an electrolyte for use in a lithium-ion electrochemical cell, the electrolyte comprising a mixture of an ethylene carbonate (EC), an ethyl methyl carbonate (EMC), a fluorinated co-solvent, a flame retardant additive, and a lithium salt. In another embodiment of the invention there is provided an electrolyte for use in a lithium-ion electrochemical cell, the electrolyte comprising a mixture of an ethylene carbonate (EC), an ethyl methyl carbonate (EMC), a flame retardant additive, a solid electrolyte interface (SEI) film forming agent, and a lithium salt.

Smart, Marshall C.↗
NASA NTRS2015

Software Graphics Processing Unit (sGPU) for Deep Space Applications

A graphics processing capability will be required for deep space missions and must include a range of applications, from safety-critical vehicle health status to telemedicine for crew health. However, preliminary radiation testing of commercial graphics processing cards suggest they cannot operate in the deep space radiation environment. Investigation into an Software Graphics Processing Unit (sGPU)comprised of commercial-equivalent radiation hardened/tolerant single board computers, field programmable gate arrays, and safety-critical display software shows promising results. Preliminary performance of approximately 30 frames per second (FPS) has been achieved. Use of multi-core processors may provide a significant increase in performance.

McCabe, Mary↗
NASA NTRSDate not supplied

Fabricating Solid-State Batteries for Electric Aviation

All-solid-state lithium batteries are widely reputed as the next major step in energy storage technology on account their drastically improved safety over wet cells, as solid electrolytes lack the volatile compounds in wet electrolytes that make them combustible. This enhanced safety enables a far wider range of products and vehicles to go fully electric and aligns with future NASA missions that require high performing, reliable, and safe batteries. However, they currently face issues with implementation in consumer products due to the often-poor mechanical properties of the solid electrolyte and relative difficulty to manufacture. Typical solid-state electrolyte challenges were bypassed by incorporating a range of polymeric binders into a solid electrolyte suspension and cast onto a composite carbon-sulfide cathode to create a single bilayer film. The resulting films display superior flexibility and durability compared to solid-electrolyte films typically discussed in literature without compromising the thinness of the films. The bilayer film was then punched into 12.7 cm diameter discs and 4 cm by 5 cm sheets, pressed, and assembled into coin cells and pouch cells respectively.

Batteries↗
NASA NTRS2024

Considerations for Using Autonomous Flight Termination Software in Crewed Launch Vehicles

Autonomous flight termination systems (AFTS) are being progressively employed onboard launch vehicles to replace ground personnel and infrastructure needed to terminate flight or destruct the vehicle should an anomaly occur. This automation uses on-board real-time data and encoded logic to determine if the flight should be self-terminated. For uncrewed launch vehicles, FTS systems are required to protect the public and governed by the United States Space Force (USSF). For crewed missions, NASA must augment range AFTS requirements for crew safety and certify each flight according to human rating standards, thus adding unique requirements for reuse of software originally intended for uncrewed missions. This bulletin summarizes new information relating to AFTS to raise awareness of key distinctions, summarize considerations and outline best practices for incorporating AFTS into human-rated systems.

Avionics↗
NASA NTRS2015

NGSLR Safety Handbook

NASA's Next Generation Satellite Laser Ranging (NGSLR) station is the prototype for NASA's Satellite Laser Ranging (SLR) systems which will be deployed around the world in the coming decade. The NGSLR system will be an autonomous, photon-counting SLR station with an expected absolute range accuracy of better than one centimeter and a normal point (time-averaged) range precision better than one millimeter. The system provides continuous (weather permitting), 24 hour tracking coverage to an existing constellation of approximately two dozen artificial satellites equipped with passive retroreflector arrays, using pulsed, 532 nm, class IV laser systems. Current details on the approved laser systems can be found in the Appendix 1 of this document. This safety plan addresses the potential hazards to emitted laser radiation, which can occur both inside and outside the shelter. Hazards within the shelter are mitigated through posted warning signs, activated warning lights, procedural controls, personal protective equipment (PPE), laser curtains, beam blocking systems, interlock controls, pre-configured laser control settings, and other controls discussed in this document. Since the NGSLR is a satellite tracking system, laser hazards exist outside the shelter to personnel on the shelter roof and to passing aircraft. Potential exposure to personnel outside the system is mitigated through the use of posted warning signs, access control, procedural controls, a stairwell interlock, beam attenuation/blocking devices, and a radar based aircraft detection system.

satellite laser ranging↗
NASA NTRS2013

Spectrum for UAS Control and Non-Payload Communications

There is an increasing need to fly UAS in the NAS to perform missions of vital importance to National Security and Defense, Emergency Management, and Science as well as commercial applications (e.g. cargo transport). To enable integration of UAS into the National Airspace System, several critical technical barriers must be eliminated, including: Separation Assurance/Sense and Avoid - the uncertainty surrounding the ability to interoperate in ATC environments and maintain safe separation from other aircraft in the absence of an on-board pilot. Human Systems Integration - lack of standards and guidelines with respect to UAS display information as well as lack of Ground Control Station (GCS) design requirements to operate in the NAS. Certification - lack of airworthiness requirements and safety-related data specific to the full range of UAS, or for their avionics systems or other components. Communications - lack of standard, certifiable data links and aviation safety spectrum to operate such links for civil UAS control communications.

Kerczewski, Robert J.↗
NASA NTRS2010

The Wettzell System Monitoring Concept and First Realizations

Automated monitoring of operational system parameters for the geodetic space techniques is becoming more important in order to improve the geodetic data and to ensure the safety and stability of automatic and remote-controlled observations. Therefore, the Wettzell group has developed the system monitoring software, SysMon, which is based on a reliable, remotely-controllable hardware/software realization. A multi-layered data logging system based on a fanless, robust industrial PC with an internal database system is used to collect data from several external, serial, bus, or PCI-based sensors. The internal communication is realized with Remote Procedure Calls (RPC) and uses generative programming with the interface software generator idl2rpc.pl developed at Wettzell. Each data monitoring stream can be configured individually via configuration files to define the logging rates or analog-digital-conversion parameters. First realizations are currently installed at the new laser ranging system at Wettzell to address safety issues and at the VLBI station O Higgins as a meteorological data logger. The system monitoring concept should be realized for the Wettzell radio telescope in the near future.

Ettl, Martin↗
NASA NTRS2010

Optimized Li-Ion Electrolytes Containing Fluorinated Ester Co-Solvents

A number of experimental lithium-ion cells, consisting of MCMB (meso-carbon microbeads) carbon anodes and LiNi(0.8)Co(0.2)O2 cathodes, have been fabricated with increased safety and expanded capability. These cells serve to verify and demonstrate the reversibility, low-temperature performance, and electrochemical aspects of each electrode as determined from a number of electrochemical characterization techniques. A number of Li-ion electrolytes possessing fluorinated ester co-solvents, namely trifluoroethyl butyrate (TFEB) and trifluoroethyl propionate (TFEP), were demonstrated to deliver good performance over a wide temperature range in experimental lithium-ion cells. The general approach taken in the development of these electrolyte formulations is to optimize the type and composition of the co-solvents in ternary and quaternary solutions, focusing upon adequate stability [i.e., EC (ethylene carbonate) content needed for anode passivation, and EMC (ethyl methyl carbonate) content needed for lowering the viscosity and widening the temperature range, while still providing good stability], enhancing the inherent safety characteristics (incorporation of fluorinated esters), and widening the temperature range of operation (the use of both fluorinated and non-fluorinated esters). Further - more, the use of electrolyte additives, such as VC (vinylene carbonate) [solid electrolyte interface (SEI) promoter] and DMAc (thermal stabilizing additive), provide enhanced high-temperature life characteristics. Multi-component electrolyte formulations enhance performance over a temperature range of -60 to +60 C. With the need for more safety with the use of these batteries, flammability was a consideration. One of the solvents investigated, TFEB, had the best performance with improved low-temperature capability and high-temperature resilience. This work optimized the use of TFEB as a co-solvent by developing the multi-component electrolytes, which also contain non-halogenated esters, film forming additives, thermal stabilizing additives, and flame retardant additives. Further optimization of these electrolyte formulations is anticipated to yield improved performance. It is also anticipated that much improved performance will be demonstrated once these electrolyte solutions are incorporated into hermetically sealed, large capacity prototype cells, especially if effort is devoted to ensure that all electrolyte components are highly pure.

Prakash, G. K. Surya↗
NASA NTRS1993

Multiple-camera/motion stereoscopy for range estimation in helicopter flight

Aiding the pilot to improve safety and reduce pilot workload by detecting obstacles and planning obstacle-free flight paths during low-altitude helicopter flight is desirable. Computer vision techniques provide an attractive method of obstacle detection and range estimation for objects within a large field of view ahead of the helicopter. Previous research has had considerable success by using an image sequence from a single moving camera to solving this problem. The major limitations of single camera approaches are that no range information can be obtained near the instantaneous direction of motion or in the absence of motion. These limitations can be overcome through the use of multiple cameras. This paper presents a hybrid motion/stereo algorithm which allows range refinement through recursive range estimation while avoiding loss of range information in the direction of travel. A feature-based approach is used to track objects between image frames. An extended Kalman filter combines knowledge of the camera motion and measurements of a feature's image location to recursively estimate the feature's range and to predict its location in future images. Performance of the algorithm will be illustrated using an image sequence, motion information, and independent range measurements from a low-altitude helicopter flight experiment.

Smith, Phillip N.↗
NASA NTRS2010

Current Trends in Satellite Laser Ranging

Satellite Laser Ranging (SLR) techniques are used to accurately measure the distance from ground stations to retroreflectors on satellites and the moon. SLR is one of the fundamental techniques that define the international Terrestrial Reference Frame (iTRF), which is the basis upon which we measure many aspects of global change over space, time, and evolving technology. It is one of the fundamental techniques that define at a level of precision of a few mm the origin and scale of the ITRF. Laser Ranging provides precision orbit determination and instrument calibration/validation for satellite-borne altimeters for the better understanding of sea level change, ocean dynamics, ice budget, and terrestrial topography. Laser ranging is also a tool to study the dynamics of the Moon and fundamental constants. Many of the GNSS satellites now carry retro-reflectors for improved orbit determination, harmonization of reference frames, and in-orbit co-location and system performance validation. The GNSS Constellations will be the means of making the reference frame available to worldwide users. Data and products from these measurements support key aspects of the GEOSS 10-Year implementation Plan adopted on February 16, 2005, The ITRF has been identified as a key contribution of the JAG to GEOSS and the ILRS makes a major contribution for its development since its foundation. The ILRS delivers weekly additional realizations that are accumulated sequentially to extend the ITRF and the Earth Orientation Parameter (EOP) series with a daily resolution. Additional products are currently under development such as precise orbits of satellites, EOP with daily availability, low-degree gravitational harmonics for studies of Earth dynamics and kinematics, etc. SLR technology continues to evolve toward the next generation laser ranging systems as programmatic requirements become more stringent. Ranging accuracy is improving as higher repetition rate, narrower pulse lasers and faster detectors are implemented. Automation and pass interleaving at some stations is already expanding temporal coverage. Web-based safety keys are allowing the SLR network stations to range to optically vulnerable satellites. Some stations are experimenting with two-wavelength operation as a means of better understanding the atmospheric refraction and with very low power laser to improve eye-safety conditions. New retroreflector designs are improving the signal link and enable daylight ranging. Dramatic improvements have also been made with lunar ranging with the new APOLLO Site in New ?Mexico, USA and the upgraded lunar station "MEO" in Grasse,

Pearlman, M. R.↗
NASA NTRS1984

Report of the Panel on Structures

Over the last 50 years, aeronautical structures have evolved from the wood, fabric, and wire of low-speed biplanes to supersonic aircraft fabricated with advanced metallic and nonmetallic materials. The advances made in structures technology have had significant impact on aircraft design and performance. An example is the large weight reductions being realized from the utilization of composite materials for secondary and primary structures. However, structural advances have been evolutionary, not revolutionary. Through the year 2000, there are opportunities to obtain significant new advancements in structural technology. These advances could result in considerable performance and capability payoffs such as increased payload, range, speed, maneuverability, fuel efficiency, and safety through reductions in weight, increases in strength, and the ability to make structures pliable. Also, with new manufacturing processes it is possible that reductions in production costs will be realized. Some of the structural technology areas where future major advances could be made are adaptive structures, thermal structures, damage tolerant structures, propulsion system structures, and new structural concepts.

Hyer, Michael W.↗
NASA NTRS1998

The X-33 range Operations Control Center

This paper describes the capabilities and features of the X-33 Range Operations Center at NASA Dryden Flight Research Center. All the unprocessed data will be collected and transmitted over fiber optic lines to the Lockheed Operations Control Center for real-time flight monitoring of the X-33 vehicle. By using the existing capabilities of the Western Aeronautical Test Range, the Range Operations Center will provide the ability to monitor all down-range tracking sites for the Extended Test Range systems. In addition to radar tracking and aircraft telemetry data, the Telemetry and Radar Acquisition and Processing System is being enhanced to acquire vehicle command data, differential Global Positioning System corrections and telemetry receiver signal level status. The Telemetry and Radar Acquisition Processing System provides the flexibility to satisfy all X-33 data processing requirements quickly and efficiently. Additionally, the Telemetry and Radar Acquisition Processing System will run a real-time link margin analysis program. The results of this model will be compared in real-time with actual flight data. The hardware and software concepts presented in this paper describe a method of merging all types of data into a common database for real-time display in the Range Operations Center in support of the X-33 program. All types of data will be processed for real-time analysis and display of the range system status to ensure public safety.

Shy, Karla S.↗
NASA NTRS2005

Expected EDL navigation performance with spacecraft to spacecraft data

Pinpoint landing (defined for the purpose of this discussion as landing within 1km of a preselected target) is a key Advanced Entry, Descent and Landing (EDL) technology for future Mars landers. Key scientific goals for Mars exploration, such as the search for water and characterization of aqueous process on Mars, the study of mineralogy and weathering of the Martian surface and the search for preserved biosignatures in Martian rocks, requires placing landers at pre-defined locations of greatest scientific interest. The capability to land within 1 km of a pre-defined landing site will improve safety and enable landing within roving range of sites of scientific interest while avoiding hazardous areas. A critical component of the closed-loop guidance, navigation and control (GN&C) system required for pinpoint landing is position and velocity estimation in real time. Spacecraft-to-spacecraft navigation will take advantage of the UHF link between two spacecraft (i.e. to an orbiter from an approaching lander for EDL telemetry relay) to build radiometric data, specifically the velocity between the two spacecraft along the radio beam, that are processed to determine position and velocity in real time. The improved onboard state knowledge provided by spacecraft-to-spacecraft navigation will reduce the landed position error and improve the performance of entry guidance. Results from the first of two years planned for this effort are documented here, including selection and documentation of prototype algorithms that will go forward into flight code along with analysis results used to define the algorithm set.

descent and landing↗