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

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At least 1,675 records · Page 93
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

Automation Hooks Architecture for Flexible Test Orchestration - Concept Development and Validation

The Automation Hooks Architecture Trade Study for Flexible Test Orchestration sought a standardized data-driven alternative to conventional automated test programming interfaces. The study recommended composing the interface using multicast DNS (mDNS/SD) service discovery, Representational State Transfer (Restful) Web Services, and Automatic Test Markup Language (ATML). We describe additional efforts to rapidly mature the Automation Hooks Architecture candidate interface definition by validating it in a broad spectrum of applications. These activities have allowed us to further refine our concepts and provide observations directed toward objectives of economy, scalability, versatility, performance, severability, maintainability, scriptability and others.

Lansdowne, C. A.↗
NASA NTRS2016

Relative Throughput of the Near-IR Science Instruments for the James Webb Space Telescope as Measured During Ground Testing the Integrated Science Instrument Module

Data were obtained for the purpose of measuring the relative throughput of the Near-IR Science Instruments (SIs) of the James Webb Space Telescope (JWST) as part of the second and third cryogenic-vacuum tests (CV2CV3) of the Integrated Science Instrument Module (ISIM) conducted at the Goddard Space Flight Center (GSFC) in 2014 and 20152016, at the beginning and end of the environmental test program, respectively. This Poster focuses on data obtained as part of the Initial Optical Baseline and as part of the Final Performance test -- two epochs that roughly bracket the CV3 test. The purpose of the test is to trend relative throughput to monitor for any potential changes from gross problems such as contamination or degradation of an optical element. Point source data were taken at a variety of wavelengths for NIRCam Module A and Module B, NIRSpec, NIRISS, Guider 1 and Guider 2 using the Laser Diode (LD) 1.06 micron, LD 1.55 micron, 2.1 micron LED and 3.5 micron LED, as well as for NIRCam Mod A and B and NIRISS using a tungsten source and the F277W, and F480M filters. Spectra were taken using the G140M, G235M, and G395M gratings for NIRSpec, the GRISMR grism for NIRCam Mod A and B and the GR150C grism for NIRISS. The results of these measurements are compared to what would be expected given the efficiency of each of the optical elements in each SI. Although these data were taken as a check against gross problems, they can also be used to provide the first relative throughput estimate for each SI through the various filters source wavelengths measured in their flight-like configurations.

technology development↗
NASA NTRS2016

Scaling Techniques for Combustion Device Random Vibration Predictions

This work presents compares scaling techniques that can be used for prediction of combustion device component random vibration levels with excitation due to the internal combustion dynamics. Acceleration and unsteady dynamic pressure data from multiple component test programs are compared and normalized per the two scaling approaches reviewed. Two scaling technique are reviewed and compared against the collected component test data. The first technique is an existing approach developed by Barrett, and the second technique is an updated approach new to this work. Results from utilizing both techniques are presented and recommendations about future component random vibration prediction approaches are given.

Kenny, R. J.↗
NASA NTRS2015

Model Generation to Support Model-Based Testing Applied on NASA DAT - An Experience Report

Model-based Testing (MBT), where a model of the system under tests (SUT) behavior is used to automatically generate executable test cases, is a promising and versatile testing technology. Nevertheless, adoption of MBT technologies in industry is slow and many testing tasks are performed via manually created executable test cases (i.e. test programs such as JUnit). In order to adopt MBT, testers must learn how to construct models and use these models to generate test cases, which might be a hurdle. An interesting observation in our previous work is that the existing manually created test cases often provided invaluable insights for the manual creation of the testing models of the system. In this paper we present an approach that allows the tester to first create and debug a set of test cases. When the tester is happy with the test cases, the next step is to automatically generate a model from the test cases. The generated model is derived from the test cases, which are actions that the system can perform (e.g. a button clicks) and their expected outputs in form of assert statements (e.g. assert data entered). The model is a Finite State Machine (FSM) model that can be employed with little or no manual changes to generate additional test cases for the SUT. We successfully applied the approach in a feasibility study to the NASA Data Access Toolkit (DAT), which is a web-based GUI. One compelling finding is that the test cases that were generated from the automatically generated models were able to detect issues that were not detected by the original set of manually created test cases. We present the findings from the case study and discuss best practices for incorporating model generation techniques into an existing testing process.

State Machines↗
NASA NTRS2019

Assessment of MON-25/MMH Propellant System for Deep-Space Engines

Hypergolic propellant system of oxidizer MON-25 and fuel MMH has been considered in propulsion trade studies for NASA science mission concepts. A propulsion system using this bi-propellant combination will be capable of operating at a lower temperature as compared to traditional MON-3/MMH for heater power reduction. Operation robustness can also be realized since such a propellant system is utilized under a wide range of temperatures. Propulsion system designs and engine test programs for MON-25/MMH have been carried out since 2008. Several engine development programs have been conducted. The thrust classes of 22-Newton [5-lb(sub f)] and 445-Newton [100-lb(sub f)] were tested with the capability of a pulse mode operation for a wide range of duty cycles. Additional engine development tests are followed. Outcomes of the development efforts suggest that there is a balance of mission benefits and potential engine design and operation challenges, although the propellants can handle a low temperature. This paper will report an assessment of using the MON-25/MMH system for deep- space application.

Trinh, Huu P.↗
NASA NTRS1991

OPAD through 1991 - Status report no. 2

The Optical Plume Anomaly Detection (OPAD) experimental program has attempted to develop a rocket engine health monitor for the detection, and if possible the quantification, of anomalous atomic and molecular species in exhaust plumes. The test program has formulated instrument designs allowing both wide spectral range and high spectral resolution. Attention is presently given to OPAD data collected for the SSME at NASA-Marshall's technology test stand, with a view to spectral emissions at startup and variations in baseline plume emissions due to changes in rated power level.

Powers, W. T.↗
NASA NTRS1991

Galileo environmental test and analysis program summary

This paper presents an overview of the Galileo Project's environmental test and analysis program during the spacecraft development phase - October 1978 through launch in October 1989. After describing the top-level objectives of the program, summaries of-the approach, requirements, and margins are provided. Examples of assembly- and system-level test results are given for both the pre-1986 (direct mission) testing and the post-1986 (Venus-Earth-Earth gravity assist mission) testing, including dynamic, thermal, electromagnetic compatibility (EMC), and magnetic. The approaches and results for verifying by analysis that the requirements of certain environments (e.g., radiation, micrometeoroids, and single event upsets) are satisfied are presented. The environmental program implemented on Galileo satisfied the spirit and intent of the requirements imposed by the Project during the spacecraft's development. The lessons learned from the Galileo environmental program are discussed in this paper.

Hoffman, A. R.↗
NASA NTRS1976

High reliability cathode heaters for ion thrusters

A number of space missions were proposed which utilize 30-cm mercury bombardment ion thrusters and also require a large number of thruster restarts. A test program was carried out to determine thermal cycle life of several different cathode heater designs. Plasma/flame sprayed heaters and swaged type heaters were tested. Four of the five plasma/flame sprayed heaters tested failed in a comparatively short time. Four tantalum swaged heaters that were brazed to the tantalum cathode tube were successfully tested and met the goals that were set at the start of the test.

Mueller, L. A.↗
NASA NTRS1976

High reliability cathode heaters for ion thrusters

A number of space missions have been proposed which will utilize 30-cm mercury bombardment ion thrusters and also will require a large number of thruster restarts. A test program was carried out to determine thermal cycle life of several different cathode heater designs. Plasma/flame sprayed heaters and swaged type heaters were tested. Four of the five plasma/flame sprayed heaters tested failed in a comparatively short time. Four tantalum swaged heaters that were brazed to the tantalum cathode tube were successfully tested and met the goals that were set at the start of the test.

Mueller, L. A.↗
NASA NTRS1976

Flight-test experience of a helicopter encountering an airplane trailing vortex

This paper presents results of a flight-test experiment of a UH-1H helicopter encountering the vortex wake of a C-54 airplane. The helicopter was instrumented to record the pilot control inputs, determine the upset experience, and measure critical loads within the rotor system. During the flight-test program 132 penetrations of the vortex wake were made by the helicopter at separation distances from 3/8 to 6-1/2 nautical miles. Test results indicated that the helicopter upsets and the vortex induced blade loads experienced were minimal and well within safe limits. The upsets were very mild when compared to a typical response of a small airplane to the vortex wake of the C-54 airplane.

Dunham, R. E., Jr.↗
NASA NTRS1978

Indoor test for thermal performance evaluation on the Sunworks (air) solar collector

The test procedure used and the results obtained from an evaluation test program conducted to obtain thermal performance data on a Sunworks single glazed air solar collector under simulated conditions are described. A time constant test and incident angle modifier test were conducted to determine the transient effect and the incident angle effect on the collector. These results and the results of the collector load test are also discussed.

Source record↗
NASA NTRS1978

Indoor test for thermal performance evaluation on life sciences engineering (air) solar collector

The test procedure used and the results obtained from an evaluation test program conducted to obtain thermal performance data on a life sciences double-glazed air solar collector under simulated conditions is discussed. These tests were made using the Marshall Space Flight Center's solar simulator. A time constant test and incident angle modifier test were also conducted to determine the transient effect and the incident angle effect on the collector. These results and the results of the collector load test are also discussed.

Source record↗
NASA NTRS1979

Standard power regulator for the multi-mission modular spacecraft

The Standard Power Regulator Unit (SPRU) which forms the central building block of the Modular Power Subsystem (MPS) for the Multi-mission Modular Spacecraft (MMS) is described. A functional description of the SPRU is presented, detailing key design features, operational characteristics, and internal redundancy as well as giving block and schematic diagrams for all major subassemblies. The description of a qualification test program consisting of ten sequences ranging from a physical examination of the unit to calculating vibration and sine sweep of power on shock tests is presented. The results showed that some significant anomalies were encountered but no catastrophic failures were indicated, although several power module failures were found due to overvoltage malfunctions of the solar array stimulator.

Kichak, R. A.↗
NASA NTRS1980

Energy Efficient High-Pressure Turbine Leakage Technology Report

The leakage test program was one of such supporting technology programs structured to provide guidance to the Energy Efficient Engine High Pressure Turbine Component Design Effort. Leakage reduction techniques were identified and evaluated. Test models were used to simulate component leak paths and to evaluate leakage reduction techniques. These models simulated the blade/disk attachment, the vane inner platform attachment, and the vane outer platform attachment combined with the blade outer airseal. Disk blade attachment testing indicated that leakage in this area could be reduced to very low levels by paying careful attention to the tolerances along the contact surface between the blade vibration damper and the blade platform contact surface. The aim of feather seal testing was to achieve a goal for an effective leakage gap of one mil (.001 inch) per inch of feather seal length. Results indicated that effective gaps even below the goal level were achievable by (1) maintaining close tolerances between feather seals and their slots to minimize end gaps and limit seal rotation, (2) avoiding feather seal overlap, and (3) minimizing feather seal intersections. W seals were shown to be effective leakage control devices. Wire rope, in its present state of development, was shown not to be an effective sealing concept for application to the component design.

Gardner, W. B.↗
NASA NTRS1985

Accelerated stress testing of thin film solar cells: Development of test methods and preliminary results

If thin film cells are to be considered a viable option for terrestrial power generation their reliability attributes will need to be explored and confidence in their stability obtained through accelerated testing. Development of a thin film accelerated test program will be more difficult than was the case for crystalline cells because of the monolithic construction nature of the cells. Specially constructed test samples will need to be fabricated, requiring committment to the concept of accelerated testing by the manufacturers. A new test schedule appropriate to thin film cells will need to be developed which will be different from that used in connection with crystalline cells. Preliminary work has been started to seek thin film schedule variations to two of the simplest tests: unbiased temperature and unbiased temperature humidity. Still to be examined are tests which involve the passage of current during temperature and/or humidity stress, either by biasing in the forward (or reverse) directions or by the application of light during stress. Investigation of these current (voltage) accelerated tests will involve development of methods of reliably contacting the thin conductive films during stress.

Lathrop, J. W.↗
NASA NTRS1987

Evaluation of cryogenic system test options for the OTV on-orbit propellant depot

Future space missions to geosynchronous, lunar, and planetary orbits will require an orbital depot for stockpiling propellants. This depot will provide long-term storage of cryogens, requiring new technologies for fluid management in microgravity and further development of thermal management technologies for minimization of cryogen boiloff. Preliminary evaluations have been made to define a test program approach for reducing technical risk through verifying performance models and building a base of engineering data for depot design. A number of testing options were defined and evaluated, leading to selection of ground testing combined with an orbital systems test. Ground testing is inadequate because of critical microgravity concerns; extending testing aboard the Space Station was eliminated because the data would not be available soon enough to benefit the propellant depot design. The orbital test would either be a short-term test carried out in the cargo bay of the Space Shuttle Orbiter using a nonhazardous cryogen or a longer term test carried out with hydrogen aboard a free-flying experiment orbited with an expendable launch vehicle.

Schuster, John R.↗
NASA NTRS1987

An innovative design for autonomous backup attitude control of the Gamma Ray Observatory

The Gamma Ray Observatory is a NASA funded three-axis stabilized spacecraft which will carry four scientific instruments to observe gamma ray phenomena. The requirement to protect the scientific mission from system failures led to the attitude control and determination system design described in this paper. The design employs nine control modes with error detection, hardware substitution, and autonomous mode switching. The system architecture evolved to eliminate cross-dependence between the primary on-board computer (OBC) and the backup control processor electronics. Cross strapping of sensors and actuators and separation of the input/output electronics ensure that a reliable set of sensors and actuators will be available for backup mode operation. The OBC software includes failure detection, hardware reconfiguration, and mode switching logic which provide the ability to autonomously transfer, upon anomaly, to a reliable backup mode. Verification of this mode transition design is done in four test programs: at the unit level, by analytical simulation, by a hybrid breadboard electronics-simulation setup, and by a flight hardware-simulation test.

Tai, F.↗