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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

An automated system for the alignment of large area modular solar simulators

A real-time optical alignment and diagnostic system is being assembled for installation at the Space Environment Simulation Laboratory. This system will be used to measure and analyze the performance of optical components, assemblies, and full modules. This information, in turn, is used to align assemblies and modules. The system capability includes such functions as the generation and updating of a catalog, which serves as permanent record, in addition to providing the capability to predict in-chamber performance of optics combinations before they are mounted in the chamber.

Vincent, J. P.↗
NASA NTRS1996

Utilization fo the Satellite Test Assistant Robot (STAR) for Visual and Thermal Analysis for Articles in the Thermal Vacuum Test Environment

An innovative new telerobotic inspection system called STAR has been developed to asist engineers in the visual and thermal analysis fo flight hardware being tested in a simulated space environment. This paper describes the architecture of the STAR mechanical and control systems and discusses some uses of STAR to date.

STAR satellite test assistant robot space simulati↗
NASA NTRS2008

Development of a Silicon Carbide Molecular Beam Nozzle for Simulation Planetary Flybys and Low-Earth Orbit

From commercial origins as a molybdenum molecular beam nozzle, a ceramic nozzle of silicon carbide (SiC) was developed for space environment simulation. The nozzle is mechanically stable under extreme conditions of temperature and pressure. A heated, continuous, supersonically-expanded hydrogen beam with a 1% argon seed produced an argon beam component of nearly 4 km/s, with an argon flux exceeding 1x1014 /cm2.s. This nozzle was part of a molecular beam machine used in the Atmospheric Experiments Branch at NASA Goddard Space Flight Center to characterize the performance of the University of Texas at Dallas Ram Wind Sensor (RWS) aboard the Air Force Communications/Navigation Outage Forecasting System (C/NOFS) launched in the Spring of 2008.

Patrick, E. L.↗
NASA NTRS1972

Optical properties of thermal control coating contaminated by MMH/N2O4 5-pound thruster in a vacuum environment with solar simulation

Cat-a-lac Black, and S13G thermal control coatings were exposed to the exhaust of a thruster in a simulated space environment. Vacuum was maintained at less than 10 to the minus 5th power torr during thruster firing in the liquid helium cooled facility. The thruster was fired in a 50-millisecond pulse mode and the accumulated firing time was 224 seconds. Solar absorptance (alpha sub s) and thermal emittance (sigma) of the coatings were measured in-situ at intervals of 300 pulses. A calorimetric technique was used to measure alpha sub s and sigma. The tests, technique, and test results are presented. The Cat-a-lac Black coatings showed no change in alpha sub s or sigma. The S13G showed up to 25 percent increase in alpha sub s but no change in sigma.

Sommers, R. D.↗
NASA NTRS1972

Optical properties of thermal control coatings contaminated by MMH/N2O4 5-pound thruster in a vacuum environment with solar simulation.

Cat-a-lac Black and S13G thermal control coatings were exposed to the exhaust of a thrustor in a simulated space environment. Vacuum was maintained at less than 10 microtorr during thrustor firing in the liquid helium cooled facility. The thrustor was fired in a 50-millisecond pulse mode, and the accumulated firing time was 224 seconds. Solar absorptance and thermal emittance of the coatings were measured in-situ at intervals of 300 pulses, using a calorimetric technique. The Cat-a-lac Black coatings showed no change in solar absorptance or thermal emittance. The S13G showed up to 25% increase in solar absorptance but no change in thermal emittance.

Sommers, R. D.↗
NASA NTRSDate not supplied

ROSA and Solar Cell Module Combined Environments Test Plan

Roll-out solar array (ROSA) technology is an emerging component of the future of spacecraft photovoltaic power subsystems. Qualification and risk reduction testing are necessary to demonstrate design worthiness for spaceflight implementation of the array and solar cell modules. Maxar Space LLC and NASA have undertaken a rigorous combined environment (CE) test campaign for a ROSA design expected to be a part of the Power and Propulsion Element (PPE) for the NASA Gateway which will be an outpost orbiting the Moon. The CE tests consist of several simulated space environment exposures associated with the planned mission: UV radiation, electron/proton radiation, xenon ion plume exposures, and vacuum thermal cycling and electrostatic discharge (ESD). These tests are conducted on small coupons consisting of the planned ROSA flight elements, and all tests are performed at the NASA Marshall Space Flight Center. This paper discusses the test plan, requirements for each environment, and the functional testing performed. Of note is a new approach for the induced primary arc used in the ESD testing, which better simulates the plasma expansion during the ESD event. Progress on executing the test plan is presented.

Space Environments Effects Testing↗
NASA NTRS2023

Using Mylar-Insulated Cryopumping Panels to Improve Vacuum Level During Warm Temperature Testing at JSC's Large Thermal Vacuum Facilities

Johnson Space Center’s Space Environment Simulation Lab (SESL) has both Chamber A, the world’s largest purpose-built thermal vacuum chamber capable of creating deep space conditions, and Chamber B, the largest human rated thermal vacuum chamber. A unique design feature of these chambers is the gaseous helium cryopumping panels within the liquid nitrogen shroud. This shroud is used to bring the chamber to cryogenic temperatures while the cryopumping panels trap gasses on its surface area to create a high vacuum environment of 5*10-6 Torr. In preparation for the James Webb Space Telescope (JWST) flight test, a series of functionals required the chamber to run at higher temperatures, and therefore did not need active cooling from the liquid nitrogen shroud. During testing, cryopumping panels were used to mitigate contamination during this main shroud warm-up. One of the cryopumping panels in Chamber A was covered with several layers of aluminized mylar to thermally protect the zone from the warmed shroud. This strategy was effective and became part of operations during JWST testing. Currently, Chamber B has requests for both commercial and NASA space suit tests at both high and low temperatures to validate thermal models. High temperature tests could benefit from reduced heater demand with an insulated shroud while still sustaining the high vacuum environment provided by the cryopumping panels. This paper will quantitatively define the thermal loads on the panels used in previous Chamber A warm up sequences. Additionally, this report will perform thermal analyses to assess the feasibility of adding layers of aluminized mylar to the cryopumping panels of Chamber B.

Cryogenics↗
NASA NTRS1973

Microbiological assay of the Marshall Space Flight Center neutral buoyancy simulator

A neutral buoyancy simulator tank system is described in terms of microbiological and medical safety for astronauts. The system was designed to simulate a gravity-free state for evaluation of orbital operations in a microorganism-free environment. Methods for the identification and elimination of specific microorganisms are dealt with as measures for a pure system of space environment simulation.

Beyerle, F. J.↗
NASA NTRS2023

Using Mylar-Insulated Cryopumping Panels to Improve Vacuum Level During Warm Temperature Testing at JSCs Large Thermal Vacuum Facilities

The Johnson Space Center’s Space Environment Simulation Lab (SESL) has both Chamber A, the world’s largest purpose-built thermal vacuum chamber capable of creating deep space conditions, and Chamber B, the largest human rated thermal vacuum chamber. A unique design feature of these chambers is the gaseous helium cryopumping panels within the liquid nitrogen shroud. This shroud is used to bring the chamber to cryogenic temperatures while the cryopumping panels trap gasses using their large surface area in order to create a high vacuum environment of 5*10^-6 Torr. In preparation for the James Webb Space Telescope (JWST) flight test, a series of functionals required the chamber to run at higher temperatures, and therefore did not need active cooling from the liquid nitrogen shroud. During testing, cryopumping panels were used to mitigate contamination during this main shroud warm-up. One of the cryopumping panels in Chamber A was covered with several layers of aluminized mylar in order to thermally protect the zone from the warmed shroud. This strategy was effective and became part of operations during JWST testing. Currently, Chamber B has requests for both commercial and NASA space suit tests at both high and low temperatures to accurately generate thermal models. High temperature tests would greatly benefit from simultaneous shroud warming and the high vacuum environment provided by the cryopumping panels. This paper will quantitatively define the thermal loads on the panels used in previous Chamber A warm up sequences. Additionally, this report will perform a thermal analysis to judge the feasibility of adding layers of aluminized mylar to the cryopumping panels of Chamber B.

Cryogenics↗
NASA NTRS2023

Using Mylar-Insulated Cryopumping Panels to Improve Vacuum Level During Warm Temperature Testing at JSC's Large Thermal Vacuum Facilities

The Johnson Space Center’s Space Environment Simulation Lab (SESL) has both Chamber A, the world’s largest purpose-built thermal vacuum chamber capable of creating deep space conditions, and Chamber B, the largest human rated thermal vacuum chamber. A unique design feature of these chambers is the gaseous helium cryopumping panels within the liquid nitrogen shroud. This shroud is used to bring the chamber to cryogenic temperatures while the cryopumping panels trap gasses using their large surface area in order to create a high vacuum environment of 5*10^-6 Torr. In preparation for the James Webb Space Telescope (JWST) flight test, a series of functionals required the chamber to run at higher temperatures, and therefore did not need active cooling from the liquid nitrogen shroud. During testing, cryopumping panels were used to mitigate contamination during this main shroud warm-up. One of the cryopumping panels in Chamber A was covered with several layers of aluminized mylar in order to thermally protect the zone from the warmed shroud. This strategy was effective and became part of operations during JWST testing. Currently, Chamber B has requests for both commercial and NASA space suit tests at both high and low temperatures to accurately generate thermal models. High temperature tests would greatly benefit from simultaneous shroud warming and the high vacuum environment provided by the cryopumping panels. This paper will quantitatively define the thermal loads on the panels used in previous Chamber A warm up sequences. Additionally, this report will perform a thermal analysis to judge the feasibility of adding layers of aluminized mylar to the cryopumping panels of Chamber B.

Cryogenics↗
NASA NTRS1984

Thermal control coatings experiment (A0138-6)

The objectives of this LDEF experiment are to verify the validity of space environment simulation performed in the laboratory in order to measure the stability of the thermo-optical properties of thermal control coatings, and to compare the behavior in space of some materials for which the available ultraviolet solar simulation is inadequate (especially in the far ultraviolet). The experimental approach is to passively expose samples of the thermal coatings of interest. These coatings include black paint, aluminum paint, white paint, a solar absorber, an optical surface reflector, second surface mirrors, metal coatings, and silica fabrics. Preflight and postflight measurements of thermo-optical properties will be compared to determine the effects of space environment exposure.

Paillous, A.↗
NASA NTRS2001

Effects of Contamination, UV Radiation, and Atomic Oxygen on ISS Thermal Control Materials

Thermal control surfaces on the International Space Station (ISS) have been tailored for optimum optical properties. The space environment, particularly contamination, ultraviolet (UV) radiation, and atomic oxygen (AO) may have a detrimental effect on these optical properties. These effects must be quantified for modeling and planning. Also of interest was the effect of porosity on the reaction to simulated space environment. Five materials were chosen for this study based on their use on ISS. The thermal control materials were Z-93 white coating, silverized Teflon, chromic acid anodized aluminum, sulfuric acid anodized aluminum, and 7075-T6 aluminum. Some of the samples were exposed to RTV 560 silicone; others were exposed to Tefzel offgassing products. Two samples of Z-93 were not exposed to contamination as clean "controls". VUV radiation was used to photo-fix the contaminant to the material surface, then the samples were exposed to AO. All samples were exposed to 1000 equivalent sun-hours (ESH) of vacuum ultraviolet radiation (VUV) at the AZ Technology facility and a minimum of 1.5 x 10(exp 20) atoms/sq cm of AO at Marshall Space Flight Center. Half of the samples were exposed to an additional 2000 ESH of VUV at Huntington Beach prior to sent to AZ Technology. Darkening of the Z-93 white coating was noted after VUV exposure. AO exposure did bleach the Z-93 but not back to its original brightness. Solar absorptance curves show the degradation due to contamination and VUV and the recovery with AO exposure. More bleaching was noted on the Tefzel-contaminated samples than with the RTV-contaminated samples.

Visentine, Jim↗
NASA NTRS2018

Evaluations of Candidate Materials for Advanced Space-Rated Vacuum Seals to Explore Space Environment Exposure Limits

For many materials used in space hardware, the environment in which they need to operate is harsher than the environment on earth. Exposure to vacuum conditions, atomic oxygen, and ultraviolet radiation can be detrimental, so testing of space hardware in simulated space environments is required. This is especially true for elastomeric components such as seals. NASA is developing advanced space-rated vacuum seals in support of future space exploration missions. These seals must exhibit extremely low leak rates to ensure that astronauts have sufficient breathable air during extended-duration missions. In some applications the seals are not mated during portions of the mission and are left uncovered and exposed to the conditions in space for prolonged periods of time prior to mating. Space-rated vacuum seals are often made of silicone because of the material's wide operating temperature range and ability to be molded or extruded into various shapes and cross sections. One approach being considered to achieve improved performance is to add titanium dioxide to the silicone material to make it more resistant to damage from ultraviolet radiation. In this study, seals made of the baseline material with and without 1.5 percent titanium dioxide additive (by weight) were exposed to atomic oxygen and increasing levels of ultraviolet radiation and then leak tested. Test results revealed that seals made of the new material could withstand longer exposures while still satisfying the leak rate requirement even under worst-case conditions of partial compression at the extremes of the anticipated operating temperature range.

Seals↗
NASA NTRS2018

Evaluations of Candidate Materials for Advanced Space-Rated Vacuum Seals to Explore Space Environment Exposure Limits

For many materials used in space hardware, the environment in which they need to operate is harsher than the environment on earth. Exposure to vacuum conditions, atomic oxygen, and ultraviolet radiation can be detrimental, so testing of space hardware in simulated space environments is required. This is especially true for elastomeric components such as seals. NASA is developing advanced space-rated vacuum seals in support of future space exploration missions. These seals must exhibit extremely low leak rates to ensure that astronauts have sufficient breathable air during extended-duration missions. In some applications the seals are not mated during portions of the mission and are left uncovered and exposed to the conditions in space for prolonged periods of time prior to mating. Space-rated vacuum seals are often made of silicone because of the material's wide operating temperature range and ability to be molded or extruded into various shapes and cross sections. One approach being considered to achieve improved performance is to add titanium dioxide to the silicone material to make it more resistant to damage from ultraviolet radiation. In this study, seals made of the baseline material with and without 1.5% titanium dioxide additive (by weight) were exposed to atomic oxygen and increasing levels of ultraviolet radiation and then leak tested. Test results revealed that seals made of the new material could withstand longer exposures while still satisfying the leak rate requirement even under worst-case conditions of partial compression at the extremes of the anticipated operating temperature range.

Ultraviolet radiation↗
NASA NTRS2001

Mid- and far-infrared spectroscopic studies of the influence of temperature, ultraviolet photolysis and ion irradiation on cosmic-type ices

Infrared (IR) studies of laboratory ices can provide information on the evolution of cosmic-type ices as a function of different simulated space environments involving thermal, ultraviolet (UV), or ion processing. Laboratory radiation experiments can lead to the formation of complex organic molecules. However, because of our lack of knowledge about UV photon and ion fluxes, and exposure lifetimes, it is not certain how well our simulations represent space conditions. Appropriate laboratory experiments are also limited by the absence of knowledge about the composition, density, and temperature of ices in different regions of space. Our current understanding of expected doses due to UV photons and cosmic rays is summarized here, along with an inventory of condensed-phase molecules identified on outer solar system surfaces, comets and interstellar grains. Far-IR spectra of thermally cycled H2O are discussed since these results reflect the dramatic difference between the amorphous and crystalline phases of H2O ice, the most dominant condensed-phase molecule in cosmic ices. A comparison of mid-IR spectra of products in proton-irradiated and UV-photolyzed ices shows that few differences are observed for these two forms of processing for the simple binary mixtures studied to date. IR identification of radiation products and experiments to determine production rates of new molecules in ices during processing are discussed. A new technique for measuring intrinsic IR band strengths of several unstable molecules is presented. An example of our laboratory results applied to Europa observations is included.

Spectrophotometry, Infrared/methods↗
NASA NTRS1982

Evaluation and prediction of long-term environmental effects on nonmetallic materials

Changes in functional properties of a broad spectrum of nonmetallic materials as a function of environment and exposure time were evaluated. Models for predicting long-term material performance are discussed. A literature search on specific materials in the space and simulated space environment was carried out and evaluated.

Source record↗