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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Corrosion study of bare and coated stainless steel

A program was conducted at Kennedy Space Center from February 1968 to February 1971 to evaluate the performance of austenitic stainless steel alloys used in fluid systems lines. For several years, there had been numerous failures of stainless steel hardware caused by pitting and stress corrosion cracking. Several alloys were evaluated for effectiveness of certain sacrificial-type protective coverings in preventing corrosion failures. Samples were tested in specially designed racks placed 91 meters (100 yards) above high-tide line at Cape Kennedy. It is concluded that: (1) unprotected tubing samples showed evidence of pitting initiation after 2 weeks; (2) although some alloys develop larger pits than others, it is probable that the actual pitting rate is independent of alloy type; (3) the deepest pitting occurred in the sheltered part of the samples; and (4) zinc-rich coatings and an aluminum-filled coating have afforded sacrificial protection against pitting for at least 28 months. It is believed that a much longer effective coating life can be expected.

Morrison, J. D.↗
NASA NTRS1990

A case study in nonconformance and performance trend analysis

As part of NASA's effort to develop an agency-wide approach to trend analysis, a pilot nonconformance and performance trending analysis study was conducted on the Space Shuttle auxiliary power unit (APU). The purpose of the study was to (1) demonstrate that nonconformance analysis can be used to identify repeating failures of a specific item (and the associated failure modes and causes) and (2) determine whether performance parameters could be analyzed and monitored to provide an indication of component or system degradation prior to failure. The nonconformance analysis of the APU did identify repeating component failures, which possibly could be reduced if key performance parameters were monitored and analyzed. The performance-trending analysis verified that the characteristics of hardware parameters can be effective in detecting degradation of hardware performance prior to failure.

Maloy, Joseph E.↗
NASA NTRS2000

ACIS Door Failure Investigation and Mitigation Procedures

NASA's Chandra X-ray Observatory (formerly AXAF) was launched on July 23, 1999 and is currently in orbit performing scientific studies. Chandra is the third of NASA's Great Observatories to be launched, following the Hubble Space Telescope and the Compton Gamma Ray Observatory. One of four primary science instruments on Chandra, and one of only two focal plane instruments, is the Advanced CCD Imaging Spectrometer, or ACIS. The ACIS focal plane and Optical Blocking Filter (OBF) must be launched under vacuum, so a tightly sealed, functioning door and venting subsystem were implemented. The door was opened two and one-half weeks after launch (after most out-gassing of composite materials) and allowed X-rays to be imaged by the ACIS CCD's in the focal plane. A failure of this door to open on-orbit would have eliminated all ACIS capabilities, severely degrading mission science. During the final pre-flight thermal-vacuum test of the fully integrated Chandra Observatory at TRW, the ACIS door failed to open when commanded to do so. This paper describes the efforts, under considerable time pressure, by NASA, its contractors and outside review teams to investigate the failure and to develop modified hardware and procedures which would correct the problem. Of interest is the fact that the root cause of the test failure was never clearly identified despite massive effort. We ultimately focussed on hardware and procedures designed to mitigate the effects of potential, but unproven, failure modes. We describe a frequent real-world engineering situation in which one must proceed on the best basis possible in the absence of the complete set of facts.

Podgorski, William A.↗
NASA NTRS2016

AirSTAR Hardware and Software Design for Beyond Visual Range Flight Research

The National Aeronautics and Space Administration (NASA) Airborne Subscale Transport Aircraft Research (AirSTAR) Unmanned Aerial System (UAS) is a facility developed to study the flight dynamics of vehicles in emergency conditions, in support of aviation safety research. The system was upgraded to have its operational range significantly expanded, going beyond the line of sight of a ground-based pilot. A redesign of the airborne flight hardware was undertaken, as well as significant changes to the software base, in order to provide appropriate autonomous behavior in response to a number of potential failures and hazards. Ground hardware and system monitors were also upgraded to include redundant communication links, including ADS-B based position displays and an independent flight termination system. The design included both custom and commercially available avionics, combined to allow flexibility in flight experiment design while still benefiting from tested configurations in reversionary flight modes. A similar hierarchy was employed in the software architecture, to allow research codes to be tested, with a fallback to more thoroughly validated flight controls. As a remotely piloted facility, ground systems were also developed to ensure the flight modes and system state were communicated to ground operations personnel in real-time. Presented in this paper is a general overview of the concept of operations for beyond visual range flight, and a detailed review of the airborne hardware and software design. This discussion is held in the context of the safety and procedural requirements that drove many of the design decisions for the AirSTAR UAS Beyond Visual Range capability.

Laughter, Sean↗
NASA NTRS1975

Man-rated flight software for the F-8 DFBW program

The design, implementation, and verification of the flight control software used in the F-8 DFBW program are discussed. Since the DFBW utilizes an Apollo computer and hardware, the procedures, controls, and basic management techniques employed are based on those developed for the Apollo software system. Program Assembly Control, simulator configuration control, erasable-memory load generation, change procedures and anomaly reporting are discussed. The primary verification tools--the all-digital simulator, the hybrid simulator, and the Iron Bird simulator--are described, as well as the program test plans and their implementation on the various simulators. Failure-effects analysis and the creation of special failure-generating software for testing purposes are described. The quality of the end product is evidenced by the F-8 DFBW flight test program in which 42 flights, totaling 58 hours of flight time, were successfully made without any DFCS inflight software, or hardware, failures.

Bairnsfather, R. R.↗
NASA NTRS2008

Space Transportation System Availability Requirements and Its Influencing Attributes Relationships

It is essential that management and engineering understand the need for an availability requirement for the customer's space transportation system as it enables the meeting of his needs, goal, and objectives. There are three types of availability, e.g., operational availability, achieved availability, or inherent availability. The basic definition of availability is equal to the mean uptime divided by the sum of the mean uptime plus the mean downtime. The major difference is the inclusiveness of the functions within the mean downtime and the mean uptime. This paper will address tIe inherent availability which only addresses the mean downtime as that mean time to repair or the time to determine the failed article, remove it, install a replacement article and verify the functionality of the repaired system. The definitions of operational availability include the replacement hardware supply or maintenance delays and other non-design factors in the mean downtime. Also with inherent availability the mean uptime will only consider the mean time between failures (other availability definitions consider this as mean time between maintenance - preventive and corrective maintenance) that requires the repair of the system to be functional. It is also essential that management and engineering understand all influencing attributes relationships to each other and to the resultant inherent availability requirement. This visibility will provide the decision makers with the understanding necessary to place constraints on the design definition for the major drivers that will determine the inherent availability, safety, reliability, maintainability, and the life cycle cost of the fielded system provided the customer. This inherent availability requirement may be driven by the need to use a multiple launch approach to placing humans on the moon or the desire to control the number of spare parts required to support long stays in either orbit or on the surface of the moon or mars. It is the intent of this paper to provide the visibility of relationships of these major attribute drivers (variables) to each other and the resultant system inherent availability, but also provide the capability to bound the variables providing engineering the insight required to control the system's engineering solution. An example of this visibility will be the need to provide integration of similar discipline functions to allow control of the total parts count of the space transportation system. Also the relationship visibility of selecting a reliability requirement will place a constraint on parts count to achieve a given inherent availability requirement or accepting a larger parts count with the resulting higher reliability requirement. This paper will provide an understanding for the relationship of mean repair time (mean downtime) to maintainability, e.g., accessibility for repair, and both mean time between failure, e.g., reliability of hardware and the system inherent availability. Having an understanding of these relationships and resulting requirements before starting the architectural design concept definition will avoid considerable time and money required to iterate the design to meet the redesign and assessment process required to achieve the results required of the customer's space transportation system. In fact the impact to the schedule to being able to deliver the system that meets the customer's needs, goals, and objectives may cause the customer to compromise his desired operational goal and objectives resulting in considerable increased life cycle cost of the fielded space transportation system.

Rhodes, Russel E.↗
NASA NTRS2020

Application of Fault Containment Principles to EMC

A hardware fault in aerospace is an undesired response to a designed engineering function in hardware. Therefore, in aerospace systems fault management is of prime importance. An important aspect of hardware faults is fault propagation. Fault propagation (also known as failure propagation) is a condition where a fault will not only produce an undesired hardware response, at its location of origin, but the fault will also propagate to other interfaced hardware and cause additional faults, or failures. Fault containment is necessary to avoid fault propagation. A fault containment region is an electronic or electromechanical region within a given hardware assembly where a fault in that region will not physically propagate to other regions of the assembly, and beyond. Rather, the fault will cause a functional failure of the hardware, where the fault occurred, without causing any additional propagated failures. Electromagnetic Compatibility (EMC) is a desired state in aerospace hardware. Electromagnetic Interference (EMI) in aerospace hardware is a fault condition of EMC. Like other faults EMI can also propagate to other aerospace hardware unless it occurs inside an EMI containment region. The paper addresses the concepts of fault containment region and introduces the concept of EMI containment region with examples of both.

Perez, Reinaldo↗
NASA NTRS2004

International Space Station (ISS) Major Constituent Analyzer (MCA) On-Orbit Performance

The Major Constituent Analyzer (MCA) is an essential part of the International Space Station (ISS) environmental control and life support system. The analyzer provides continuous readout of the partial pressures of six gases, nitrogen (N2), oxygen (O2), hydrogen (H2), carbon dioxide (CO2), methane (CH4) and water vapor (H2O) in the various ISS US. on-orbit modules. Continuous readout of the partial pressures of these gases is critical to verifying safe operation of the Atmosphere Revitalization (AR) system, Atmosphere Control System (ACS), and crew safety for Airlock Extravehicular Activities (EVAs). The MCA encountered some operational interruptions since being launched to orbit on Flight 5A in February 2001. Electronic, software, and hardware modifications and on-orbit crew maintenance of the MCA were necessary to restore its capability. This paper describes the modifications and the on-orbit maintenance performed to return the MCA to operational status, including brief explanations of the MCA failures and the associated hardware and electronic modifications. Operational procedures that were required to return the MCA to operational status, and the more recent successes of supporting both Russian and U.S. ISS EVA preparations, are also discussed

Reysa, Richard↗
NASA NTRS1983

Autonomous failure detection and correction on Landsat-4

An integrated hardware/software fault tolerant system for an earth oriented, computer controlled spacecraft is described. The design philosophy as well as the rationale behind the chosen fault tolerant system is outlined. In-flight performance of the system is included for several different instances where the Failure Detection and Correction system acted autonomously to protect the spacecraft. This system exceeded the expectations of the designers by demonstrating the capability to provide a measure of safety to the spacecraft for inadvertent and undesirable ground commands as well as satisfying its primary function of monitoring the flight hardware and software for failures.

Welch, R. V.↗
NASA NTRS1973

Redundancy management of inertial systems.

The paper reviews developments in failure detection and isolation techniques applicable to gimballed and strapdown systems. It examines basic redundancy management goals of improved reliability, performance and logistic costs, and explores mechanizations available for both input and output data handling. The meaning of redundant system reliability in terms of available coverage, system MTBF, and mission time is presented and the practical hardware performance limitations of failure detection and isolation techniques are explored. Simulation results are presented illustrating implementation coverages attainable considering IMU performance models and mission detection threshold requirements. The implications of a complete GN&C redundancy management method on inertial techniques are also explored.

Mckern, R. A.↗
DOE OSTI2020

CalWave Open Water Demo - FMEA Update Budget Period 2

The Failure Modes and Effects Analysis (FMEA) is a qualitative reliability technique for systematically analyzing each possible failure mode within a hardware system, and identifying the resulting effect on that system, the mission, and the personnel. This submission includes an updated FMEA summary for CalWave's open water demonstration including pre- and post-mitigation results, hazard identification (HAZID) analysis, and component/function rooted FMEA.

16 TIDAL AND WAVE POWER↗
DOE OSTI2026

Complete time-resolved X-ray shape capability for a 10 MJ implosion: Milestone Report for MRT 8818

This report documents completion of MRT 8818, which established an upgraded equatorial time-resolved X-ray imaging capability for high-yield inertial confinement fusion experiments at the National Ignition Facility (NIF) using the equatorial Dilation X-ray Imager (DIXI). The need for this work arose from the sustained increase in fusion yield at NIF, which progressively intensified the neutron and gamma-ray environment experienced by target diagnostics. Although the existing polar imaging capability, particularly the Polar Dilation X-ray Imager (PDIXI), remained viable at high yields, the equatorial capability became inadequate because of radiation-induced failure of electronic readout hardware and increasing background levels that degraded image quality and ultimately caused saturation. The work performed under MRT 8818 addressed this limitation through a combination of hardware replacement, background characterization, and targeted mitigation. The DIXI backend was converted from CCD-based electronic readout to photographic film, and the principal sources of internally generated background were investigated using prior analyses, dedicated tests, and comparison with PDIXI performance on high-yield shots. This effort led to implementation of two principal improvements: a multilayer optical coating to suppress broadband radiation-induced background generated in the fiber-optic extension cylinder, and replacement of Kodak TMAX 400 film with Agfa Copex Rapid to reduce background generated directly in the film. These upgrades were completed in 2025 and performance assessment based on DT shot data since then, comparing with Polar DIXI and scaling of these experiments to 10 MJ indicates an expected signal-to-background ratio of approximately 34 for a single pinhole image, substantially exceeding the MRT 8818 completion criterion of SNR > 5.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1971

Lunar module program system safety

The application of system safety principles to the Lunar Module Program is summarized. Objectives of the program include elimination or reduction of risk to personnel, material, and facilities resulting from failures or malfunctions in hardware or procedures. Data also cover design, production, and test activity.

William E. Scarborough↗
NASA NTRS1974

Nondestructive evaluation of electroformed outer shells for regeneratively cooled thrust chambers

Electroforming is presently a prime technique for producing the outer jackets of regeneratively cooled thrust chambers for rocket engines. Good bond integrity of the electroformed joints adjacent to the coolant passages is important to the useful service life of these aerospace systems. This investigation demonstrated that nondestructive evaluation techniques such as ultrasonic 'C' scan, holography, and acoustic emission are capable of detecting low integrity bonds which could lead to premature failures in the subject hardware.

Malone, G. A.↗
NASA NTRS1982

Galileo spacecraft power distribution and autonomous fault recovery

There is a trend in current spacecraft design to achieve greater fault tolerance through the implemenation of on-board software dedicated to detecting and isolating failures. A combination of hardware and software is utilized in the Galileo power system for autonomous fault recovery. Galileo is a dual-spun spacecraft designed to carry a number of scientific instruments into a series of orbits around the planet Jupiter. In addition to its self-contained scientific payload, it will also carry a probe system which will be separated from the spacecraft some 150 days prior to Jupiter encounter. The Galileo spacecraft is scheduled to be launched in 1985. Attention is given to the power system, the fault protection requirements, and the power fault recovery implementation.

Detwiler, R. C.↗
NASA NTRS1990

Fault-tolerant, embedded CLIPS applications

The enhancements to CLIPS4.3 presented in this paper provide an embedded CLIPS application with the ability to continue operation with minimal to no loss of information in the event of a hardware or a software failure. Given an arbitrary failure, the CLIPS application's environment (fact-list, agenda, and pattern matching network) will be reconstructed to the point at which the failure was experienced. The environment reconstruction is based on state files to which the application periodically checks environment information (fact-list and agenda). The routine for checkpointing the state of the application is as efficient as possible so that the overhead introduced to normal execution of the application is minimal. The only assumptions made by the CLIPS application are that it is running under an operating system that guarantees it access to uncorrupt state files and that the application will be automatically restarted should it terminate abnormally.

Hicks, Jaye↗