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At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

An Overview of the Runtime Verification Tool Java PathExplorer

We present an overview of the Java PathExplorer runtime verification tool, in short referred to as JPAX. JPAX can monitor the execution of a Java program and check that it conforms with a set of user provided properties formulated in temporal logic. JPAX can in addition analyze the program for concurrency errors such as deadlocks and data races. The concurrency analysis requires no user provided specification. The tool facilitates automated instrumentation of a program's bytecode, which when executed will emit an event stream, the execution trace, to an observer. The observer dispatches the incoming event stream to a set of observer processes, each performing a specialized analysis, such as the temporal logic verification, the deadlock analysis and the data race analysis. Temporal logic specifications can be formulated by the user in the Maude rewriting logic, where Maude is a high-speed rewriting system for equational logic, but here extended with executable temporal logic. The Maude rewriting engine is then activated as an event driven monitoring process. Alternatively, temporal specifications can be translated into efficient automata, which check the event stream. JPAX can be used during program testing to gain increased information about program executions, and can potentially furthermore be applied during operation to survey safety critical systems.

Havelund, Klaus↗
NASA NTRS1977

Space Shuttle Orbiter approach and landing program status

The space shuttle approach and landing test (ALT) program is being conducted in four phases. The first phase, completed in March of 1977, consisted of verifying the airworthiness of the mated B-747 shuttle carrier aircraft and orbiter. The second phase consists of checking the orbiter systems in captive flight. The third phase is to be confined to launching the orbiter with and without the tail cone installed to evaluate the final landing phase of the shuttle operations through the verification of the automatic landing system. The fourth and final phase of the program is to document the mated configuration's performance relative to the ferry operations to be conducted between the return from the orbiter's landing sites and launch sites. This paper presents the results of the SCA inert orbiter flight testing and the program plans up to the completion of the ALT program.

Andrews, W. H.↗
NASA NTRS1979

Integrated testing and verification system for research flight software design document

The NASA Langley Research Center is developing the MUST (Multipurpose User-oriented Software Technology) program to cut the cost of producing research flight software through a system of software support tools. The HAL/S language is the primary subject of the design. Boeing Computer Services Company (BCS) has designed an integrated verification and testing capability as part of MUST. Documentation, verification and test options are provided with special attention on real time, multiprocessing issues. The needs of the entire software production cycle have been considered, with effective management and reduced lifecycle costs as foremost goals. Capabilities have been included in the design for static detection of data flow anomalies involving communicating concurrent processes. Some types of ill formed process synchronization and deadlock also are detected statically.

Taylor, R. N.↗
NASA NTRS1997

Towards High-Assurance High-Performance Program Synthesis

Domain-specific automatic program synthesis tools, also called application generators, are playing an ever-increasing role in software development. However, high-performance application generators require difficult manual construction, and are very difficult to verify correct. This paper describes research and an implemented system that transforms program synthesis tools based on deductive synthesis into high-performance application generators. Deductive synthesis uses theorem-proving to construct solutions when given problem specifications. The verification condition for a deductive synthesis tool is essentially the soundness of the implemented inference rules. Theory Operationalization for Program Synthesis (TOPS) synergistically combines reformulation, automated mathematical classification, and compilation through partial deduction to decision procedures. It transforms general-purpose deductive synthesis, with exponential performance, into efficient special-purpose deductive synthesis, with near-linear performance. This paper describes our experience with and empirical results of PD(TH) theory-based partial deduction - in which partial deduction of a set of first-order formulae is performed within the context of a background theory. The implemented TOPS system currently performs a special variant of PD(TH) in which the compilation process results in the transformation of a set of first order formulae into the theory of an instantiated library decision procedure augmented by a compiled unit theory.

Lowry, Michael↗
NASA NTRS1987

Verification of an analytic modeler for capillary pump loop thermal control systems

A number of computer programs have been written to model two-phase heat transfer systems for space use. These programs support the design of thermal control systems and provide a method of predicting their performance in the wide range of thermal environments of space. Predicting the performance of one such system known as the capillary pump loop (CPL) is the intent of the CPL Modeler. By modeling two developed CPL systems and comparing the results with actual test data, the CPL Modeler has proven useful in simulating CPL operation. Results of the modeling effort are discussed, together with plans for refinements to the modeler.

Schweickart, R. B.↗
NASA NTRS1990

Experimental verification of a tank to tank He II transfer model with trade study results

A computer program has been developed to study the thermodynamics of tank to tank superfluid helium transfer. The model includes a supply and a receiver tank connected by a transfer line. The convey of He II from one tank to the other is controlled by a fountain effect pump (FEP). Phase separators are present in both the supply and receiver tank to regulate the bath temperature. Description of this model has been published elsewhere. In the present paper, data from a transfer experiment are used to verify the accuracy of this model. The experiment consisted of an FEP made of a 2-micron sintered stainless steel porous plug. Superfluid has been transferred from a liquid helium bath into a glass beaker. Bath temperatures, flowrate and heater power records are available. These results are compared to the predictions of the computer program and good agreement is found between the two. This model is very useful for the study and design of superfluid transfer systems, e.g., the Superfluid Helium Tanker (SFHT) and the Particle Astrophysics Magnet Facility (ASTROMAG).

Yuan, S. W. K.↗
NASA NTRS2008

The ESA Large Space Simulator Mechanical Ground Support Equipment for Spacecraft Testing

Environmental test facilities are not suitable in any case to comply with special or complex test requirements without modifications. Dedicated upgrades of the test facility and their subsystems with respect to the test requirements and specifications are often necessary. The Flight Model of the Planck Space Telescope was tested in the Large Space Simulator (LSS) of the ESTEC Test Centre. Main goals of the test were the verification of the deformation of the Telescope during thermal vacuum conditions at different temperature levels and the validation of the Thermal Model. The deformations of the telescope have been traced by two Videogrammetry canisters. In order to provide different view positions with respect to the PLANCK Telescope it was necessary to rotate the specimen by +/- 180deg. In addition very stringent requirements for the low temperature level of the thermal environment has lead to a comprehensive test set-up which was divided in four main elements: Dedicated support structure for the Videogrammetry canisters providing several DoF for adjustment. Structure to support three Infrared panels around the specimen. MLI curtain to cover the LSS 8m auxiliary chamber opening. System providing LN2 supply for the rotating PLANCK telescope cold panel. The design, manufacturing and integration of the necessary mechanical ground support to install for instance the canisters and to ensure the 180 rotation of the telescope under cold and high vacuum conditions was an extensive and important part of the entire test program. This paper will concentrate on the design issues, the implementation and verification of the MGSE provided for the Planck Space Telescope FM Videogrammetry Test in the LSS and the troubleshooting caused by a failure during the first rotation under cold conditions.

Hagelschuer, Dirk↗
NASA NTRS1990

Expendable launch vehicles technology: A report to the US Senate and the US House of Representatives

As directed in Public Law 100-657, Commercial Space Launch Act Amendments of 1988, and consistent with National Space Policy, NASA has prepared a report on a potential program of research on technologies to reduce the initial and recurring costs, increase reliability, and improve performance of expendable launch vehicles for the launch of commercial and government spacecraft into orbit. The report was developed in consultation with industry and in recognition of relevant ongoing and planned NASA and DoD technology programs which will provide much of the required launch systems technology for U.S. Government needs. Additional efforts which could be undertaken to strengthen the technology base are identified. To this end, focus is on needs for launch vehicle technology development and, in selected areas, includes verification to permit private-sector new technology application at reduced risk. If such a program were to be implemented, it would entail both government and private-sector effort and resources. The additional efforts identified would augment the existing launch vehicle technology programs. The additional efforts identified have not been funded, based upon agency assessments of relative priority vis-a-vis the existing programs. Throughout the consultation and review process, the industry representatives stressed the overriding importance of continuing the DoD/NASA Advanced Launch Development activity and other government technology programs as a primary source of essential launch vehicle technology.

Source record↗
NASA NTRS2004

Advanced Global Atmospheric Gases Experiment (AGAGE)

We seek funding from NASA for the third year (2005) of the four-year period January 1, 2003 - December 31, 2006 for continued support of the MIT contributions to the multi-national global atmospheric trace species measurement program entitled Advanced Global Atmospheric Gases Experiment (AGAGE). The case for real-time high-frequency measurement networks like AGAGE is very strong and the observations and their interpretation are widely recognized for their importance to ozone depletion and climate change studies and to verification issues arising from the Montreal Protocol (ozone) and Kyoto Protocol (climate). The proposed AGAGE program is distinguished by its capability to measure over the globe at high frequency almost all of the important species in the Montreal Protocol and almost all of the significant non-CO2 gases in the Kyoto Protocol.

Prinn, Ronald G.↗
NASA NTRS2004

A Sustainable, Reliable Mission-Systems Architecture that Supports a System of Systems Approach to Space Exploration

A mission-systems architecture based on a highly modular "systems of systems" infrastructure utilizing open-standards hardware and software interfaces as the enabling technology is absolutely essential for an affordable and sustainable space exploration program. This architecture requires (a) robust communication between heterogeneous systems, (b) high reliability, (c) minimal mission-to-mission reconfiguration, (d) affordable development, system integration, and verification of systems, and (e) minimum sustaining engineering. This paper proposes such an architecture. Lessons learned from the space shuttle program are applied to help define and refine the model.

Watson, Steve↗
NASA NTRS1989

A real-time simulator of a turbofan engine

A real-time digital simulator of a Pratt and Whitney F100 engine has been developed for real-time code verification and for actuator diagnosis during full-scale engine testing. This self-contained unit can operate in an open-loop stand-alone mode or as part of closed-loop control system. It can also be used for control system design and development. Tests conducted in conjunction with the NASA Advanced Detection, Isolation, and Accommodation program show that the simulator is a valuable tool for real-time code verification and as a real-time actuator simulator for actuator fault diagnosis. Although currently a small perturbation model, advances in microprocessor hardware should allow the simulator to evolve into a real-time, full-envelope, full engine simulation.

Litt, Jonathan S.↗
NASA NTRS2022

Pre-Installation Acceptance (PIA) Functional Performance of the Design Verification Test (DVT) Exploration Extra-vehicular Mobility Unit (xEMU)

In an effort that began with technology investment by NASA in a few key components during the Constellation Program and then evolved to demonstrate a packaged Portable Life Support System (PLSS) as part of the Advanced Exploration Systems (AES) Program, the next evolution of the PLSS is now a key component of the Exploration Extra-vehicular Mobility Unit (xEMU) and is assembled as a Design Verification Test (DVT) unit. The xEMU has been detailed with respect to completing a demonstration on the International Space Station (ISS) with support of units for initial lunar capability. The xEMU completed the Preliminary Design Review (PDR) with subsequent Safety Review Panel (SRP) Phase I reviews in 2019-2020. The objectives for DVT are to validate requirements, train the team, learn how to fabricate the hardware with appropriate process controls, assemble the hardware, test the hardware, determine the failure mechanisms/limits of the hardware design and buy down the most risk possible for the qualification and flight phases of the development. With completion of the assembly and initial functional testing of the DVT PLSS in laboratory ambient conditions and vacuum conditions the xEMU has progressed significantly into the DVT objectives. A key part of the test sequences for DVT and all future phases is the Pre-Installation Acceptance (PIA) functional testing which validates the performance of integrated systems including: primary thermal control, auxiliary thermal control, suit ventilation, primary oxygen, secondary oxygen, power distribution, as well as caution and warning all with respect to the applied requirements. This discussion will include an overview of the assembly, summary of the PIA functional testing, lessons learned, and corrective actions implemented moving forward into the remainder of the DVT phase for xEMU.

Colin Campbell↗
NASA NTRS1972

Apollo experience report: Electronic systems test program accomplishments and results

A chronological record is presented of the Electronic Systems Test Program from its conception in May 1963 to December 1969. The original concept of the program, which was primarily a spacecraft/Manned Space Flight Network communications system compatibility and performance evaluation, is described. The evolution of these concepts to include various levels of test detail, as well as systems level design verification testing, is discussed. Actual implementation of these concepts is presented, and the facility to support the program is described. Test results are given, and significant contributions to the lunar landing mission are underlined. Plans for modifying the facility and the concepts, based on Apollo experience, are proposed.

Ohnesorge, T. E.↗
NASA NTRSDate not supplied

Revisiting the Soyuz-1 Parachute Failure in the Context of Safety in the Modern Era

The Soyuz‑1 accident remains one of the most consequential parachute related failures in human spaceflight history and provides enduring lessons for modern Entry, Descent, and Landing (EDL) system design. Occurring during the height of the Cold War and the Space Race, the mission unfolded under extraordinary political and schedule pressure as the Soviet Union sought to maintain its early leadership in space achievements following the death of chief designer Sergei Korolev. Despite unresolved propulsion, electrical, and parachute system deficiencies, Soyuz‑1 proceeded to launch and immediately encountered critical inflight anomalies, including a failed solar panel deployment, attitude control issues, and communication dropouts. Upon reentry, a malfunction in the parachute system, driven by a primary main canopy that failed to deploy, and subsequent entanglement of the reserve main canopy with the primary drogue parachute, resulted in insufficient deceleration and the fatal crash of cosmonaut Vladimir Komarov. Subsequent investigations revealed deep rooted cultural and organizational issues within the Soviet space program, including inadequate testing, suppression of dissent, undocumented last minute design changes, and the absence of integrated parachute system verification. More than 200 design flaws were identified after the accident, and firsthand accounts, including those from Yuri Gagarin, highlighted widespread concern prior to launch. Over time, the Soviet program implemented substantial reforms: systematic design corrections, rigorous process documentation, and an extensive series of drop tests that ultimately transformed the Soyuz system into one of the world’s most reliable human-rated return vehicles. This paper examines the technical architecture of the Soyuz‑1 parachute system, reconstructs the likely deployment sequence and failure mechanism, and analyzes the cultural contributors that shaped the accident. The study draws parallels to modern spacecraft parachute development, emphasizing the critical importance of integrated system testing, transparent engineering culture, and continuous hardware surveillance. These lessons remain directly relevant to today’s NASA and Commercial Crew Programs (CCP), where the Government continues to refine its understanding of aggregate risk and strengthen overall astronaut safety in the face of increasingly complex parachute systems.

Aaron L Morris↗
NASA NTRS2000

Assessment of Thermal Control and Protective Coatings

This final report is concerned with the tasks performed during the contract period which included spacecraft coating development, testing, and applications. Five marker coatings consisting of a bright yellow handrail coating, protective overcoat for ceramic coatings, and specialized primers for composites (or polymer) surfaces were developed and commercialized by AZ Technology during this program. Most of the coatings have passed space environmental stability requirements via ground tests and/or flight verification. Marker coatings and protective overcoats were successfully flown on the Passive Optical Sample Assembly (POSA) and the Optical Properties Monitor (OPM) experiments flown on the Russian space station MIR. To date, most of the coatings developed and/or modified during this program have been utilized on the International Space Station and other spacecraft. For ISS, AZ Technology manufactured the 'UNITY' emblem now being flown on the NASA UNITY node (Node 1) that is docked to the Russian Zarya (FGB) utilizing the colored marker coatings (white, blue, red) developed by AZ Technology. The UNITY emblem included the US American flag, the Unity logo, and NASA logo on a white background, applied to a Beta cloth substrate.

Mell, Richard J.↗
NASA NTRS1992

The post Challenger era Get Away Special program January 1992

The Get Away Special (GAS) program is described in terms of the changes that have taken place in both NASA and the GAS itself. Attention is given to the relationships developed between NASA and GAS customers in the context of programmatic and technical issues. The background of the GAS program is outlined with reference given to policy publications, the design of the Flight Verification Payload, and the first GAS payload launched. A review process is described that facilitates the management of the payloads through flight certification. The GAS Bridge was developed to carry up to 12 payloads simultaneously, and the recent period of GAS inactivity is explained. A price increase is introduced for future GAS payloads with negotiable access to optional services, and the ease and accessibility of the GAS programs for private experiments is emphasized.

Prouty, Clarke↗
NASA NTRS1975

Digital command system

The correct processing of the Digital Command System (DCS), which provides a limited real-time means of controlling specific flight program functions, was verified. The ability of the flight program to correctly read and process DCS commands was verified. Tests made by the flight program after reading the contents of the command decoder register to establish the validity of the received data were verified through the following: DCS mode command verification, DCS data command verification, DCS data validation, and DCS error message. The operation of the following DCS commands accepted and processed by the flight program was tested: time base update, navigation update, generalized switch selector, memory dump, terminate, execute generalized maneuver, return to nominal timeline, ECS water control valve logic inhibit, execute maneuver, execute alternate sequence, targeting load, ladder magnitude limit, S-IVB/IU de-orbit, compressed data dump, and remove inhibit on the extraction maneuver.

Source record↗
NASA NTRS1993

Effects of rotation on coolant passage heat transfer. Volume 2: Coolant passages with trips normal and skewed to the flow

An experimental program was conducted to investigate heat transfer and pressure loss characteristics of rotating multipass passages, for configurations and dimensions typical of modem turbine blades. This experimental program is one part of the NASA Hot Section Technology (HOST) Initiative, which has as its overall objective the development and verification of improved analysis methods that will form the basis for a design system that will produce turbine components with improved durability. The objective of this program was the generation of a data base of heat transfer and pressure loss data required to develop heat transfer correlations and to assess computational fluid dynamic techniques for rotating coolant passages. The experimental work was broken down into two phases. Phase 1 consists of experiments conducted in a smooth wall large scale heat transfer model. A detailed discussion of these results was presented in volume 1 of a NASA Report. In Phase 2 the large scale model was modified to investigate the effects of skewed and normal passage turbulators. The results of Phase 2 along with comparison to Phase 1 is the subject of this Volume 2 NASA Report.

Johnson, B. V.↗