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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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

A Mirror Transport Mechanism for Use at Cryogenic Temperatures

This report describes the Mirror Transport Mechanism (MTM), which supports a pair of dihedral mirrors and moves them in a very smooth and uniform scanning motion normal to a beamsplitter. Each scan is followed by a quick flyback and repeat. Included in the report will be material selection, design, and testing of all major components of the MTM in order to meet the stringent performance requirements under cryogenic conditions and survive the launch environment of the shuttle. Areas to be discussed in detail will be those in which failures or performance anomalies occurred and their solutions. Typically, this will include (but not to be limited to) flex pivot failures during vibration testing, excessive dihedral platform sag under one "g" operation, electronic and fiber optic characteristics, and tolerancing considerations. As of this writing, development of the mechanism has reached the final phase of thermal and vibration qualification. Environmental testing of the complete FIRAS (Far Infrared Absolute Spectrophotometer) experiment is just beginning.

Stark, Kenneth W.↗
NASA NTRS1972

Time and temperature dependent modulus of pyrrone and polyimide moldings

A method is presented by which the modulus obtained from a stress relaxation test can be used to estimate the modulus which would be obtained from a sonic vibration test. The method was applied to stress relaxation, sonic vibration, and high speed stress-strain data which was obtained on a flexible epoxy. The modulus as measured by the three test methods was identical for identical test times, and a change of test temperature was equivalent to a shift in the logarithmic time scale. An estimate was then made of the dynamic modulus of moldings of two Pyrrones and two polyimides, using stress relaxation data and the method of analysis which was developed for the epoxy. Over the common temperature range (350 to 500 K) in which data from both types of tests were available, the estimated dynamic modulus value differed by only a few percent from the measured value. As a result, it is concluded that, over the 500 to 700 K temperature range, the estimated dynamic modulus values are accurate.

Lander, L. L.↗
NASA NTRS1976

Mariner Jupiter/Saturn LCSSE thruster/valve assembly and injection propulsion unit rocket engine assemblies: 0.2-lbf T/VA development and margin limit test report, addendum

Capillary tube plugging phenomena on the 0.2-lbf thruster/valve assembly was examined. Vibration tests were conducted in the nozzle up attitude. Failure to fire caused by blockage of the capillary tube by catalyst fines was observed after vibration. Water flushing and previbration hot firing were used to remove the fines.

Wilson, W. W.↗
NASA NTRS1988

Passive damping concepts for free and forced member and grillage vibration

The performance of potential passive damping concepts is investigted for a long tubular aluminum alloy member, and a two-bar grillage structure. The members are restrained partially at the ends and are of the type being considered by NASA for possible use in the construction of a future space station. Four different passive damping concepts are studied and include nylon brush, wool swab, copper brush, and silly putty in chamber dampers. Both free and forced vibration tests are conducted. It is found that the silly putty in chamber damper concept provides considerably greater passive damping as compared to that of the other three concepts. For the grillage natural vibration, a five wool swab damper configuration provides greater damping than the five silly putty dampers in chamber configuration. Due to the constrained motion imposed by the vibrator used in the tests, the effectiveness of the passive dampers could not be adequately evaluated for the individual member. However, it is found that for the grillage under forced vibration, the five silly putty dampers in chamber damper configuration provides very effective passive damping although only at and around the resonant frequency. At resonance, these dampers provide a 51 percent reduction in the dynamic magnification factor for this case.

Razzaq, Zia↗
NASA NTRS1970

Testing to insure mission success

Qualification and testing procedures for Apollo Spacecraft Program components and systems, discussing vibration tests

Simpkinson, S. H.↗
NASA NTRS1975

Dual shear plate power processor packaging design

The use of solar electric propulsion (SEP) for spacecraft primary propulsion imposes an extreme range of operational and environmental design requirements associated with the diversity of missions for which solar electric primary propulsion is advantageous. One SEP element which is particularly sensitive to these environmental extremes is the power processor unit (PPU) which powers and controls the electric ion thruster. An improved power processor thermal-mechanical packaging approach, referred to as dual shear plate packaging, has been designed to accommodate these different requirements with minimum change to the power processor design. Details of this packaging design are presented together with test results obtained from thermal-vacuum and structural-vibration tests conducted with prototype hardware.

Franzon, A. O.↗
NASA NTRS1977

Space Shuttle Program Progress Report

A status report is presented on progress in the design, manufacturing and testing of components of the space transportation system (STS), and primarily the Space Shuttle vehicles. Project landmarks from 1969 to 1981 are indicated, fabrication of the Shuttle Orbiter and rollout of the first prototype are described, fabrication and assembly of some Orbiter parts are sketched, and some of the subsystems (thermal protection, avionics, maneuvering aids, reaction control, remote manipulator) are described. Also discussed are: Orbiter carrier aircraft, Shuttle main engine and tests, external fuel tank, solid rocket booster, launch and landing facilities. A separate section is devoted to ground tests (vibration, propulsion, electronics, avionics integration), trainers and simulators, and flight tests (captive flight, free flight, landing and approach, orbital flight).

Thompson, R. F.↗
NASA NTRS2004

Performance and Vibration of 30 cm Pyrolytic Ion Thruster Optics

Carbon has a sputter erosion rate about an order of magnitude less than that of molybdenum, over the voltages typically used in ion thruster applications. To explore its design potential, 30 cm pyrolytic carbon ion thruster optics have been fabricated geometrically similar to the molybdenum ion optics used on NSTAR. They were then installed on an NSTAR Engineering Model thruster, and experimentally evaluated over much of the original operating envelope. Ion beam currents ranged from 0.51 to 1.76 Angstroms, at total voltages up to 1280 V. The perveance, electron back-streaming limit, and screen-grid transparency were plotted for these operating points, and compared with previous data obtained with molybdenum. While thruster performance with pyrolytic carbon was quite similar to that with molybdenum, behavior variations can reasonably be explained by slight geometric differences. Following all performance measurements, the pyrolytic carbon ion optics assembly was subjected to an abbreviated vibration test. The thruster endured 9.2 g(sub rms) of random vibration along the thrust axis, similar to DS 1 acceptance levels. Despite significant grid clashing, there was no observable damage to the ion optics assembly.

Haag, Thomas↗
NASA NTRS2002

In situ testing of a satellite or other object prior to development

A method and system for testing a test object, such as a satellite, is disclosed. High energy acoustic testing is performed on the object by assembling an acoustical system about the test object rather than transporting the test object to a specially configured acoustic chamber. The acoustic system of the present invention preferably provides and directs acoustic energy directly to the surfaces of the test object rather than providing the test object in a high energy acoustic environment where a substantial amount of the acoustic energy is randomly directed within a chamber having the test object. Additionally, the present invention further provides for mechanical vibration tests concurrently or serially with acoustic testing, wherein the object is not required to be transported.

Eagen, James H.↗
NASA NTRS2020

Comprehensive Radiation Testing of Uncooled, Free Space Coupled, InGaAs Quad Photoreceivers

We have comprehensively tested uncooled, free space coupled, InGaAs Quad Photoreceivers having 0.5mm, 1mm, and 2mm diameter integrated with a low noise transimpedance amplifier (TIA)using 30MeV Protons, 100MeV Protons, 662keV Gamma Rays, 1GeV/n Helium, and 1GeV/n Iron at room temperature of ~20°C.These devices find multiple applications in space for differential wave front sensing as part of a Gravitational Wave Observatory, as well as instrumentation and control for next generation space telescopes. The bandwidth of all receivers was 20MHz which was TIA limited. All 0.5mm and 1mm devices were found to be fully functional at normal operating conditions and at room temperature for Protons, Gamma Rays, 1GeV/n Helium, and 1GeV/n Iron. Only one quadrant of a 2mm In GaAs Quad had hard failure due to 1GeV/n Helium Ions; otherwise it too survived all other radiation tests. Detailed test results follow in the manuscript including recommendations for future space flights. These radiation test results, combined with the earlier successful mechanical shock and vibration testing mean these devices have passed preliminary testing for space qualification.

Abhay M Joshi↗
NASA NTRS1976

Vibration characteristics of 1/8-scale dynamic models of the space-shuttle solid-rocket boosters

Vibration tests and analyses of six 1/8 scale models of the space shuttle solid rocket boosters are reported. Natural vibration frequencies and mode shapes were obtained for these aluminum shell models having internal solid fuel configurations corresponding to launch, midburn (maximum dynamic pressure), and near endburn (burnout) flight conditions. Test results for longitudinal, torsional, bending, and shell vibration frequencies are compared with analytical predictions derived from thin shell theory and from finite element plate and beam theory. The lowest analytical longitudinal, torsional, bending, and shell vibration frequencies were within + or - 10 percent of experimental values. The effects of damping and asymmetric end skirts on natural vibration frequency were also considered. The analytical frequencies of an idealized full scale space shuttle solid rocket boosted structure are computed with and without internal pressure and are compared with the 1/8 scale model results.

Leadbetter, S. A.↗
NASA NTRS2014

Development Testing and Subsequent Failure Investigation of a Spring Strut Mechanism

The NASA Engineering and Safety Center (NESC) and Lockheed Martin (LM) performed random vibration testing on a single spring strut development unit to assess its ability to withstand qualification level random vibration environments. Failure of the strut while exposed to random vibration resulted in a follow-on failure investigation, design changes, and additional development tests. This paper focuses on the results of the failure investigations referenced in detail in the NESC final report including identified lessons learned to aid in future design iterations of the spring strut and to help other mechanism developers avoid similar pitfalls.

Dervan, Jared↗
NASA NTRS2014

Development Testing and Subsequent Failure Investigation of a Spring Strut Mechanism

The NASA Engineering and Safety Center (NESC) and Lockheed Martin (LM) performed random vibration testing on a single spring strut development unit to assess its ability to withstand qualification level random vibration environments. Failure of the strut while exposed to random vibration resulted in a follow-on failure investigation, design changes, and additional development tests. This paper focuses on the results of the failure investigations referenced in detail in the NESC final report [1] including identified lessons learned to aid in future design iterations of the spring strut and to help other mechanism developers avoid similar pitfalls.

Dervan, Jared↗
NASA NTRS1972

Structural evaluations and dynamic testing of solar electric propulsion components.

Results of an experimental and analytical study of selected Solar Electric Propulsion (SEP) thrust subsystem components are presented. A mass and center-of-mass mockup of an experimental power conditioning (PC) panel was used for the PC structure evaluation. Test environment was based on that specified for prooftesting the Viking spacecraft electronics. Modal frequencies were surveyed over the range of 0-2000 Hz using both conventional test equipment and the holographic interferometry technique. Results of the forced vibration tests point to the need for some additional stiffening to make the structure qualifiable.

Womack, J. R.↗
NASA NTRS2019

Laboratory-Based Thermal Shock Investigation of Heat Flux Sensors for the Mars 2020 Backshell

In 2012 during the entry, descent, and landing of the Mars Science Laboratory (MSL), the MSL Entry, Descent, and Landing Instrumentation (MEDLI) sensor suite was collecting in-flight heatshield pressure and temperature data. The data collected by the MEDLI instruments has since been used for reconstruction of vehicle aerodynamics, atmospheric conditions, aerothermal heating, and Thermal Protection System (TPS) performance as well as material response model validation and refinement. The Mars Entry, Descent, and Landing Instrumentation 2 (MEDLI2) sensor suite for the Mars 2020 heatshield and backshell is being designed to expand on the measurements and knowledge gained from MEDLI. Similar to MEDLI, MEDLI2 will measure the pressure and temperature of the heatshield. MEDLI2 will additionally measure the temperature, pressure, total heat flux, and radiative heat flux on the backshell. Since the backshell instrumentation is new to MEDLI2, Do No Harm (DNH) testing was conducted on instrumented backshell TPS (SLA-561V) panels. The panels consisted of four pressure port holes, one Mars Entry Atmospheric Data System (MEADS) pressure port plug, one MEDLI2 Integrated Sensor Plug (MISP) thermal plug, and one heat flux sensor. DNH testing was conducted to ensure the performance of the TPS was not degraded due to sensor integration and to characterize any TPS performance changes. The testing consisted of environmental testing— vibration, shock, thermal vacuum (TVAC) cycling— and bounding aerothermal (arc jet) testing.

Miller, R. A.↗
NASA NTRS1988

Random vibration (stress screening) of printed wiring assemblies

The results of a random vibration test screening (RVSS) study of the determination of the upper and lower vibration limits on printed wiring assemblies (PWA) are summarized. The study results are intended to serve as a guide for engineers and designers who make decisions on PWA features that need to withstand the stresses of dynamic testing and screening. The maximum allowable PWA deflection, G levels, and PSD levels are compared to the expected or actual levels to determine if deleterious effects will occur.

Bastien, Gilbert J.↗
NASA NTRS2005

Space Shuttle Columbia Aging Wiring Failure Analysis

A Space Shuttle Columbia main engine controller 14 AWG wire short circuited during the launch of STS-93. Post-flight examination divulged that the wire had electrically arced against the head of a nearby bolt. More extensive inspection revealed additional damage to the subject wire, and to other wires as well from the mid-body of Columbia. The shorted wire was to have been constructed from nickel-plated copper conductors surrounded by the polyimide insulation Kapton, top-coated with an aromatic polyimide resin. The wires were analyzed via scanning electron microscope (SEM), energy dispersive X-Ray spectroscopy (EDX), and electron spectroscopy for chemical analysis (ESCA); differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) were performed on the polyimide. Exemplar testing under laboratory conditions was performed to replicate the mechanical damage characteristics evident on the failed wires. The exemplar testing included a step test, where, as the name implies, a person stepped on a simulated wire bundle that rested upon a bolt head. Likewise, a shear test that forced a bolt head and a torque tip against a wire was performed to attempt to damage the insulation and conductor. Additionally, a vibration test was performed to determine if a wire bundle would abrade when vibrated against the head of a bolt. Also, an abrasion test was undertaken to determine if the polyimide of the wire could be damaged by rubbing against convolex helical tubing. Finally, an impact test was performed to ascertain if the use of the tubing would protect the wire from the strike of a foreign object.

McDaniels, Steven J.↗