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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Changes in some physical properties induced by vacuum heat treatment

A method is proposed for reducing or eliminating outgassing of materials by heat treating them in vacuum prior to use. This may be performed on the raw material prior to manufacturing and installation or after fabrication of parts. Processing of a fabricated part can be performed only on relatively small parts and on assemblies containing no components which are affected by the required temperatures and pressures. Processing conditions of temperature and time are dependent on the particular application and the materials involved. Silicone-coated fiber glass cloth was vacuum-heat treated for 100 hrs at 400 + or - 25 F at pressures of 0.001 torr or less. The materials were tested in terms of tensile strength and tear properties in both the smooth and several creased configurations. Data obtained on one side silicone coated fiber glass showed large reductions in these properties as a result of the vacuum-heat treatment. The problem was alleviated by coating both sides of the fiber glass.

Hultquist, A. E.↗
NASA NTRS1978

A facility for the simulation of environmental parameters and qualification of flight thermal coatings

There is a continuing interest and need for investigation and development of, various paints, coatings, multi-layer insulation, and electrically conductive paints and coatings used for thermal control and electrical discharge of spacecraft surfaces. Degradation of these surfaces by solar-wind energy particles and ultraviolet irradiation, as well as contamination by the outgassing of materials used in conjunction or close proximity to these surfaces, continues to be a matter of concern. The following is a description of a facility with the capability of evaluating the synergistic effects encountered in the space environment. Actual flight qualification programs are also described.

Paczkowski, F. N.↗
NASA NTRS1982

Shuttle optical environment; Proceedings of the Meeting, Washington, DC, April 23, 24, 1981

The numerical modeling, instrumentation, identification, and procedures to characterize and/or control contamination hazards to equipment used on the Shuttle are discussed. On-orbit pollutants include molecular offgassing and outgassing, particulate material, and substances from thrusters, vents, and leaks. Clean-rooms are being implemented in ground assembly and integration facilities. Attention is given to an upgraded SPACE program for numerically modeling contamination pathways and appropriate procedures to protect instrumentation from film and particulate deposition. Finally, attention is given to military cryogenic IR detectors being employed to quantify the Shuttle thermal and solid pollutant environment on-orbit as a prelude to future operational IR sensors.

Miller, E. R.↗
NASA NTRS1985

CU in space: The University of Colorado get away special payload G-285

The University of Colorado's first Get Away Special was conceived by a dozen science and engineering students in the spring of 1984. Since that time, the project has grown to include over 100 undergraduate and graduate students who have 'provided the experimental objectives, design, construction, integration, testing and management of the payload. Faculty and staff of the university and its affiliated laboratories as well as engineers from local industries have provided many useful suggestions at all stages of development. The principal motivation for developing this payload is to provide university students with the opportunity to participate in space science and engineering beginning at the ground level. At the same time, they are contributing their results from new science and technological discoveries to several disciplines. There are four separate experiments integrated into the /'single payload of G-285 which are supported by internal payload !power, thermal environment control, command land data handling [ facilities and structural subsystems. The four experiments contained in this payload are: a single spectrometer performing i two experiments- one to study night time shuttle glow phenomena in the ultraviolet and the other to observe NO2 concentrations over / equatorial latitudes in the day; a fluids management experiment ' using centrifugation for particle/liquid/vapor separation; and an experiment using Phycomyces fungi to study the gravireceptor mechanism theory. The experiments are supported by a microprocessor, data storage devices, power and thermal control subsystems. All these are located within a sealed aluminum container. The container, a refitted sounding rocket casing, has a top and bottom which bolt to the main body of the rocket section. The top section holds a five inch diameter quartz window through which light enters the spectrometer. A rotating mirror assembly and one of two battery boxes are mounted on the outside of the top section below the interface plane of the MDA. A second battery box is attached to the bottom section of the sealed container. All payload items except the battery boxes and mirror assembly are located inside the sealed rocket section to insure containment and to prevent outgassing of materials. The container will be sealed prior to launch and purged with one atmosphere of argon.

Kent Tobiska↗
NASA NTRS1991

New aspects relating to the behaviour of composites and adhesives in space

Some of the specialized testing procedures performed at the JPL Molecular Contamination Investigation Facility for the WideField Planetary Camera II (WFPC II) program for the screening of polymeric materials for outgassing properties are described. For WFPC II, a science performance goal of 1-percent photometric accuracy at 1470 A over an extended time (at least 30 days) has been established. Utilization of the newest technology using CCD detectors poses even more stringent requirements. Test results are presented, and data reduction and modeling techniques are discussed.

Carpenter, A.↗
NASA NTRS1992

Results from testing and analysis of solar cells flown on LDEF

A brief discussion of the solar cell experiments flown on the Long Duration Exposure Facility (LDEF) is provided. The information presented is a collation of results published by the various experimenters. This process of collation and documentation is an ongoing Systems Special Investigation Group (SIG) effort. There are four LEO environments, operating individually and/or synergistically, that cause performance loss in solar cells: meteoroid and space debris, atomic oxygen, ultraviolet radiation, and charged particle radiation. In addition, the effects of contamination caused by outgassing of materials used on the specific spacecraft play a role in decreasing the light being transmitted through the coverglass and adhesive to the solar cell. From the results presented on the solar cells aboard LDEF, the most extensive degradation of the solar cells came from impacts and the resulting cratering. The extent of the damage to the solar cells was largely dependent upon the size and energy of the meteoroids or space debris. The other cause of degradation was reduced light reaching the solar cell. This was caused by contamination, UV degradation of coverglass adhesive, and/or atomic oxygen/UV degradation of antireflection coatings.

Dursch, Harry↗
NASA NTRS1995

Whisker/Cone growth on the thermal control surfaces experiment no. S0069

An unusual surface 'growth' was found during scanning electron microscope (SEM) investigations of the Thermal Control Surface Experiment (TCSE) S0069 front thermal cover. This 'growth' is similar to the cone type whisker growth phenomena as studied by G. K. Wehner beginning in the 1960's. Extensive analysis has identified the most probable composition of the whiskers to be a silicate type glass. Sources of the growth material are outgassing products from the experiment and orbital atomic oxygen, which occurs naturally at the orbital altitudes of the LDEF mission in the form of neutral atomic oxygen. The highly ordered symmetry and directionality of the whiskers are attributed to the long term (5.8 year) stable flight orientation of the LDEF.

Zwiener, James M.↗
NASA NTRS2015

Lotus Dust Mitigation Coating and Molecular Adsorber Coating

NASA Goddard Space Flight Center has developed two unique coating formulations that will keep surfaces clean and sanitary and contain contaminants.The Lotus Dust Mitigation Coating, modeled after the self-cleaning, water-repellant lotus leaf, disallows buildup of dust, dirt, water, and more on surfaces. This coating, has been successfully tested on painted, aluminum, glass, silica, and some composite surfaces, could aid in keeping medical assets clean.The Molecular Adsorber Coating is a zeolite-based, sprayable molecular adsorber coating, designed to prevent outgassing in materials in vacuums. The coating works well to adsorb volatiles and contaminates in manufacturing and processing, such as in pharmaceutical production. The addition of a biocide would also aid in controlling bacteria levels.

protective coatings↗
NASA NTRS1984

Composition, Structure and Evolution of Uranian and Neptunian Satellites

Large uncertainties in the current estimated densities of all of these satellites prevent detailed modeling or predictions. Nevertheless, current evidence suggests that at least Titania and Oberon might have anomalously high densities of 2-39 cm(-3), possibly requiring almost ice-free hydrated silicates or formation in a CO-rich environment, implying presence of CO-clathrate and a small ice/rock ratio. Trition and the four largest satellites of Uranus are massive enough to have undergone significant accretional heating and early differentiation; NH3-H2O volcanism; partial outgassing of CO, N2, Ch4; formation of dark surficial deposits of carbon-rich material obtained by UV irradiation of outgassed material; and, at least in the cases of Ariel and Triton, a possibility of weak ongoing icy volcanic activity. Triton may be the largest captured body in the solar system, with an unusual history and composition, including the possibility of substantial liquid or solid nitrogen obtained from either primordial NH3 photolysis or clathrate decomposition.

Stevenson, D. J.↗
NASA NTRS1996

Hygrothermal properties of composites

The testing procedure and acceptance criteria for outgassing selection of materials to be used in spacecraft has been reviewed. Outgassing testing should be conducted according to ASTM Standard E 595-90. In general, materials with CVCM less than or equal to 0.10% and TML less than or equal to 1.00% are acceptable for space applications. Next, test data on several types of graphite-epoxy composite materials are presented over time at various relative humidity levels at room temperature for moisture absorption, and under vacuum at several temperatures for moisture desorption (outgassing). The data can be accurately represented by simple equations which are useful for materials characterization. Finally, a laser dilatometer systems of extremely high sensitivity and accuracy was assembled and used to measure the coefficient of thermal expansion (CTE) of several types of graphite-epoxy structures, culminating in the ability to perform loading and thermal expansion tests on a prototype optical bench.

Arsenovic, Petar↗
NASA NTRS1984

Contamination Measurements During Ius Thermal Vacuum Tests in A Large Space Chamber

The levels of contamination that originate from inside the IUS equipment support section (ESS) due to outgassing from electronics components and wiring operating at elevated temperatures (80-160 F) were investigated. Pressure was measured inside and outside the ESS. Mass deposition measurements were made with quartz crystal microbalances (QCM) facing into and away from ESS vents. The OCM's were operated at -50 C and -180 C using thermoelectrically and cryogenically cooled QCM's. Gaseous nitrogen flow inside the ESS was used to obtain the effective molecular flow vent area of the ESS, which was evaluated to be 359 sq cm (56 sq in) compared to the 978 sq cm (150 sq in) estimated by an earlier atmosphere pressure billowing test. The total outgassing rate of the ESS materials at a temperature of 60 C (140 F) decays with a time constant of 11.5 hours based on pressure measurements during the hot cycle. A time constant of 22 hours was estimated for the fraction of the outgassing which will condense on a -50 C surface. In contrast, the time constant is only 10.1 hours for the outgassing material which condenses on a surface at -180 C. A surface at -180 C collects approximately one half of the material vented from the ESS which impinges on it. Pressure measurements show very good correlation with the mass deposition measurements.

C R Mullen↗
NASA NTRS1978

Techniques used for limiting degradation products of polymeric materials for use in the space environment

Techniques are discussed for limiting or controlling the degradation products (outgassing) of polymeric materials in the space environment. One technique, now ASTM E-595-77, is used to screen out those materials which lose greater than 1% Total Mass Loss when in vacuum for 24 hours at 125 C and which have more than 0.10% Collected Volatile Condensable Materials condensing on a collector surface at 25 C. Examples of silicone materials which are high and low in outgassing are given. The numerous mechanical motions in spacecraft experiments require liquid lubricants which also might degrade in space. Labyrinth seals and barrier films are utilized to limit the degradation of or from these lubricants. A recoverable in-flight experiment has been proposed for making definitive measurements of how effective these techniques are in limiting the amounts and escape paths of outgassed molecules.

Vest, C. E.↗
NASA NTRS1977

Toxicological aspects of the Skylab program

A current state-of-the-art trace gas removal technology is demonstrated that provides for carbon monoxide removal through an outgassing screening program for nonmetallic materials of the Skylab cabin interior. Material selection included both outgassing data and LD sub 50 information, as well as chemical analyses on pyrolysis products to prevent toxic inhalation exposures of spacecrews.

Rippstein, W. J., Jr.↗
NASA NTRS1972

Outgassing and contamination properties of prospective Apollo Telescope Mount materials.

Some of the test techniques used to evaluate the outgassing and contamination characteristics of prospective Apollo telescope mount (ATM) materials are reviewed. These include a screening test providing information on weight losses of materials, weights of their condensed outgas products, and white-light scattered by the condensed products. They also include an ultraviolet-region screening test and a comprehensive continuous in situ weight-loss test. Examples are presented of data obtained from each of the tests on various prospective ATM materials.

Poehlmann, H. C.↗
NASA NTRS1994

Self contamination effects in the TAUVEX UV Telescope: Ground testing and computer simulation

The contamination effects due to outgassing from construction materials of the TAUVEX (Tel Aviv University UV Telescope) were evaluated using a combination of ground testing and computer simulations. Tests were performed from the material level of the system level including: (1) High sensitivity CVCM(10(exp -3 percent) measurements of critical materials. (2) Optical degradation measurements of samples specially contaminated by outgassing products at different contamination levels. (3) FTIR studies of chemical composition of outgassed products on above samples. (4) High resolution AFM studies of surface morphology of contaminated surfaces. The expected degradation of TAUVEX performance in mission was evaluated applying a computer simulation code using input parameters determined experimentally in the above tests. The results have served as guidelines for the proper selection of materials, cleanliness requirements, determination of the thermal conditions of the system and bakeout processes.

Lifshitz, Y.↗
NASA NTRS2004

Quartz Crystal Microbalance Operation and In Situ Calibration

Quartz crystal microbalances (QCMs) are commonly used to measure the rate of deposition of molecular species on a surface. The measurement is often used to select materials with a low outgassing rate for applications where the material has a line of sight to a contamination-sensitive surface. A quantitative, in situ calibration of the balance, or balances, using a pure material for which the enthalpy of sublimation is known, is described in this Technical Memorandum. Supporting calculations for surface dwell times of deposited materials and the effusion cell Clausing factor are presented along with examples of multiple QCM measurements of outgassing from a common source.

Albyn, K. C.↗
NASA NTRS1970

Evaluation of polymeric products for use in thermal-vacuum environment

Of 350 materials screened for outgassing characteristics, 100 qualify within the limits of less than 1 percent weight loss and less than 0.1 percent VCM /volatile condensible material/ content. Infrared absorbence spectra of the VCM from 96 polymeric products and an interim list of recommended products are identified.

Muraca, R. F.↗