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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 1,171 records · Page 65
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Effect of metallurgical structure and properties on adhesion and friction behavior of cobalt alloys

The metallurgical structure and some of the mechanical properties of two cobalt alloys, cobalt-50% iron and cobalt-25% molybdenum-10% chromium, were determined under various heat treated conditions. The mechanical properties of the bcc disordered Co-50Fe alloy, which was found to be very brittle, indicated an exceedingly low fracture strength, low hardness, and very weak grain boundary strength. Ordering by suitable heat treatment only produced a more brittle material with a lower fracture strength and a slightly higher hardness value. Work hardening was found to produce a finer grain structure and a greater grain boundary strength. Tensile properties were examined. It was found that the Co-25Mo-10Cr alloy was difficult to place in the alpha Co solid solution condition, which limited the ability to use precipitation as a hardening reaction. Over two hundred adhesion cycles from zero contact load, to maximum load, to fracture were conducted between couples for each of the above alloys in an ultrahigh vacuum system which would permit the sample surfaces to be cleaned of all contaminant layers. In the Co-50Fe case, the calculated fracture stress from the adhesion tests showed values in the range of 80 to 150 k.s.i., which is about ten times greater than the values from tension tests.

Keller, D. V., Jr.↗
NASA NTRS1973

Estimating the number of terrestrial organisms on the moon.

Methods used to obtain estimates for the biological loadings on moon bound spacecraft prior to launch are reviewed, along with the mathematical models used to calculate the microorganism density on the lunar surface (such as it results from contamination deposited by manned and unmanned flights) and the probability of lunar soil sample contamination. Some of the results obtained by the use of a lunar inventory system based on these models are presented.

Dillon, R. T.↗
NASA NTRS1976

Aseptic fluid-transfer system

Inexpensive storage and transfer system allows blood and other fluids to be added or removed without contamination. Device heat-sterilizes external surfaces of terminals and forms sterile passageway between terminals.

Arnett, J. C.↗
NASA NTRS1975

Value contamination avoidance devices

Mechanical redesign methods were used to minimize contamination damage of conventional fluid components and a contamination separator device was developed for long term reusable space vehicles. These were incorporated into an existing 50.8 mm poppet valve and tested for damage tolerance in a full size open loop flow system with gaseous and liquid nitrogen. Cyclic and steady flow conditions were tested with particles of 125 to 420 micrometers aluminum oxide dispersed in the test fluids. Nonflow life tests (100,000 cycles) were made with two valve configurations in gaseous hydrogen. The redesigned valve had an acceptable cycle life and improved tolerance to contamination damage when the primary sealing surfaces were coated with thin coatings of hard plastic (Teflon S and Kynar). Analytical studies and flow testing were completed of four different versions of the separator. overall separation efficiencies in the 55-90% range were measured with these non-optimum configurations.

Endicott, D. L.↗
NASA NTRS1980

JANTX1N5614 switching siode

Diode manufactured by Micro Semiconductor and Semtech were tested. Main failure mode was surface inversions caused by leakage of contaminants through cracks in glass. Most failures in groups 2 and 3 were visual.

Source record↗
NASA NTRS1979

Ion beam texturing of surfaces

Textured surfaces, typically with conical structures, have been produced previously by simultaneously etching a surface and seeding that surface with another material. A theory based on surface diffusion predicts a variation in cone spacing with surface temperature, as well as a critical temperature below which cones will not form. Substantial agreement with theory has been found for several combinations of seed and surface materials, including one with a high sputter yield seed on a low sputter yield surface (gold on aluminum). Coning with this last combination was predicted by the theory for a sufficiently mobile seed material. The existence of a minimum temperature for the formation of cones should also be important to those interested in ion-beam machining smooth surfaces. Elements contained in the environmental contaminants or in the sputtered alloys or compounds may serve as seed material.

Kaufman, H. R.↗
NASA NTRS1987

Remote sensing of snow

The snow parameters affecting sensor responses at different wavelengths are discussed. The effects of snow depth and background radiation on gamma ray sensors and of crystal size, contaminants, snow depth, liquid water, and surface roughness on visible and near-infrared sensors are considered. The influence of temperature, crystal size, and liquid water on thermal infrared sensors and of liquid water, crystal size, water equivalent depth, stratification, snow surface roughness, density, temperature, and soil condition on microwave sensors are addressed.

Foster, J. L.↗
NASA NTRS1988

The possible contamination of Jupiter

The Galileo probe, though at present its future is uncertain, would, if not sterilized, represent a good chance of contaminating Jupiter. Most scientists opposed to sterilizing the probe argue that to order the probe sterilized would be the death of the project, since sterilization would entail a reconstruction of the probe, and there are not enough funds to accomplish this. These scientists, however, are ignoring a relatively simple and inexpensive alternative to the traditional heat sterilization method. The main threat of contamination comes from Galileo's exterior surfaces: the shell of the probe and its parachute. The probe innermost components would not represent a threat since the probe is sealed. In light of the fact that only the exterior of Galileo would have to be sterilized, heat would not have to be used as a method of sterilization. Instead, various gas mixtures could be sprayed entirely over the probe and its parachute, gases which would kill any and all bacteria. This idea is more thoroughly examined.

Garcia, Joe↗
NASA NTRS1992

Optical characterization of contaminant film

The so called 'nicotine stain' documented at many locations on the Long Duration Exposure Facility is still unexplained as to the exact origin and mechanism of deposition, although enough is known to have some understanding of the conditions coincident for the formation of the deposits. Direct and scattered atomic oxygen flux, and solar ultraviolet radiation interacting with materials outgassing products have all been implicated in the formation of the dark brown contamination deposits. The nicotine stain represents a potential of performance degradation for spacecraft designed for long term operation in low Earth orbit and therefore, a need exists to characterize this form of spacecraft self contamination and quantify the impact on thermal/optical systems. Optical property measurements in the spectral range of 2 to 10 microns were performed on specimens of the contaminated film. Reflectance measurements of the contaminant film as deposited on the surface and as free standing films are presented along with transmission spectra for the bulk material. Thickness measurements along with micrographic examination of the cross section of the deposit reveal the layered structure of the deposit which further implicates solar illumination as a factor in the deposition mechanism.

Blakkolb, Brian K.↗
NASA NTRS1992

Aerobraking Magellan

While the Magellan spacecraft is currently in an elliptical orbit around Venus, its orbit may be circularized by means of an aerobraking maneuver during which a minor amount of aerodynamic drag is applied to 1000-2000 orbits. An evaluation is presently undertaken of the thermal-control and operational problems arising from such a maneuver, in virtue of its not having been considered among the design requirements of the spacecraft. Attention is given to atmospheric erosion and contamination problems to which the spacecraft surfaces could be exposed.

Lyons, Daniel T.↗
NASA NTRS1993

Analysis of leading edge and trailing edge cover glass samples before and after treatment with advanced satellite contamination removal techniques

Two samples from Long Duration Exposure Facility (LDEF) experiment M0003-4 were analyzed for molecular and particulate contamination prior to and following treatment with advanced satellite contamination removal techniques (CO2 gas/solid jet spray and oxygen ion beam). The pre- and post-cleaning measurements and analyses are presented. The jet spray removed particulates in seconds. The low energy reactive oxygen ion beam removed 5,000 A of photo polymerized organic hydrocarbon contamination in less than 1 hour. Spectroscopic analytical techniques were applied to the analysis of cleaning efficiency including: Fourier transform infrared, Auger, x ray photoemissions, energy dispersive x ray, and ultraviolet/visible. The results of this work suggest that the contamination studied here was due to spacecraft self-contamination enhanced by atomic oxygen plasma dynamics and solar UV radiation. These results also suggest the efficacy for the jet spray and ion beam contamination control technologies for spacecraft optical surfaces.

Hotaling, S. P.↗
NASA NTRS1994

EVA-SCRAM operations

This paper wrestles with the on-orbit operational challenges introduced by the proposed Space Construction, Repair, and Maintenance (SCRAM) tool kit for Extra-Vehicular Activity (EVA). SCRAM undertakes a new challenging series of on-orbit tasks in support of the near-term Hubble Space Telescope, Extended Duration Orbiter, Long Duration Orbiter, Space Station Freedom, other orbital platforms, and even the future manned Lunar/Mars missions. These new EVA tasks involve welding, brazing, cutting, coating, heat-treating, and cleaning operations. Anticipated near-term EVA-SCRAM applications include construction of fluid lines and structural members, repair of punctures by orbital debris, refurbishment of surfaces eroded by atomic oxygen, and cleaning of optical, solar panel, and high emissivity radiator surfaces which have been degraded by contaminants. Future EVA-SCRAM applications are also examined, involving mass production tasks automated with robotics and artificial intelligence, for construction of large truss, aerobrake, and reactor shadow shield structures. Realistically achieving EVA-SCRAM is examined by addressing manual, teleoperated, semi-automated, and fully-automated operation modes. The operational challenges posed by EVA-SCRAM tasks are reviewed with respect to capabilities of existing and upcoming EVA systems, such as the Extravehicular Mobility Unit, the Shuttle Remote Manipulating System, the Dexterous End Effector, and the Servicing Aid Tool.

Flanigan, Lee A.↗
NASA NTRS1996

Passive Optical Sample Assembly (POSA-2) Space Flight Experiment

NASA Lewis Research Center's Electro-Physics Branch is participating in the POSA-2 Space Flight Experiment to assess the effects of low Earth orbit and spacecraft environment contamination on power system materials and surfaces. This experiment package will be flown for 1 year in low Earth orbit and will be returned to Earth for subsequent evaluation of optical and thermal properties. Representative samples of solar array blanket materials, solar dynamic reflector materials, thermal control coatings, and sapphire are included in the experiment package.

Source record↗
NASA NTRS2004

Clean then Assemble Versus Assemble then Clean: Several Comparisons

Cleanliness of manufactured parts and assemblies is a significant issue in many industries including disk drives, semiconductors, aerospace, and medical devices. Clean manufacturing requires cleanroom floor space and cleaning technology that are both expensive to own and expensive to operate. Strategies to reduce these costs are an important consideration. One strategy shown to be effective at reducing costs is to assemble parts into subassemblies and then clean the subassembly, rather than clean the individual parts first and then assemble them. One advantage is that assembly outside of the cleanroom reduces the amount of cleanroom floor space and its associated operating cost premium. A second advantage is that this strategy reduces the number of individual parts that must be cleaned prior to assembly, reducing the number of cleaning baskets, handling and, possibly, reducing the number of cleaners. The assemble then clean strategy also results in a part that is significantly cleaner because contamination generated during the assembly steps are more effectively removed that normally can be achieved by hand wiping after assembly in the cleanroom.

contamination↗
NASA NTRS2006

Genesis Solar Wind Sample Curation: A Progress Report

In the year since the Genesis solar wind collector fragments were returned, early science samples, specimens for cleaning experiments, and science allocations have been distributed. Solar wind samples are stored under nitrogen and handled in an ISO Class 4 (Class 10) laboratory. For array collector fragments, a basic characterization process has been established. This characterization consists of identification of solar wind regime, whole fragment image for identification and surface quality, higher magnification images for contaminant particle density, and assessment of molecular film contaminant thickness via ellipsometry modeling. Compilations of this characterization data for AuOS (gold film on sapphire), and sapphire from the bulk solar wind for fragments greater than 2 cm are available. Removal of contaminant particles using flowing ultrapure water (UPW) energized megasonically is provided as requested.

Allton, Judith H.↗
NASA NTRS2012

Heat Melt Compaction as an Effective Treatment for Eliminating Microorganisms from Solid Waste

One of the technologies being tested at Ames Research Center as part of the logistics and repurposing project is heat melt compaction (HMC) of solid waste to reduce volume, remove water and render a biologically stable and safe product. Studies at Kennedy Space Center have focused on the efficacy of the heat melt compaction process for killing microorganisms in waste and specific compacter operation protocols, i.e., time and temperature, required to achieve a sterile, stable product. The work reported here includes a controlled study to examine the survival and potential re-growth of specific microorganisms over a 6-month period of storage after heating and compaction. Before heating and compaction, ersatz solid wastes were inoculated with Bacillus amyloliquefaciens and Rhodotorula mucilaginosa, previously isolated from recovered space shuttle mission food and packaging waste. Compacted HMC tiles were sampled for microbiological analysis at time points between 0 and 180 days of storage in a controlled environment chamber. In addition, biological indicator strips containing spores of Bacillus atrophaeus and Ceo bacillus stearothermophilus were imbedded in trash to assess the efficacy of the HMC process to achieve sterilization. Analysis of several tiles compacted at 180 C for times of 40 minutes to over 2 hours detected organisms in all tile samples with the exception of one exposed to 180 C for approximately 2 hours. Neither of the inoculated organisms was recovered, and the biological indicator strips were negative for growth in all tiles indicating at least local sterilization of tile areas. The findings suggest that minimum time/temperature combination is required for complete sterilization. Microbial analysis of tiles processed at lower temperatures from 130 C-150 C at varying times will be discussed, as well as analysis of the bacteria and fungi present on the compactor hardware as a result of exposure to the waste and the surrounding environment. The two organisms inoculated into the waste were among those isolated and identified from the HMC surfaces indicating the possibility of cross contamination.

Hummerick, Mary P.↗
NASA NTRS2013

Heat Melt Compaction as an Effective Treatment for Eliminating Microorganisms from Solid Waste

One of the technologies being tested at Ames Research Center as part of the logistics and repurposing project is heat melt compaction (HMC) of solid waste to reduce volume, remove water and render a biologically stable and safe product. Studies at Kennedy Space Center have focused on the efficacy of the heat melt compaction process for killing microorganisms in waste and specific compacter operation protocols, i.e., time and temperature required to achieve a sterile, stable product. The work. reported here includes a controlled study to examine the survival and potential re-growth of specific microorganisms over a 6-month period of storage after heating and compaction. Before heating and compaction, ersatz solid wastes were inoculated with Bacillus amyloliquefaciens and Rhodotorula mucilaginosa, previously isolated from recovered space shuttle mission food and packaging waste. Compacted HMC tiles were sampled for microbiological analysis at time points between 0 and 180 days of storage in a controlled environment chamber. In addition, biological indicator strips containing spores of Bacillus atrophaeus and Geobacillus stearothermophilus were imbedded in trash to assess the efficacy of the HMC process to achieve sterilization. Analysis of several tiles compacted at 180deg C for times of 40 minutes to over 2 hours detected organisms in all tile samples with the exception of one exposed to 180deg C for approximately 2 hours. Neither of the inoculated organisms was recovered, and the biological indicator strips were negative for growth in all tiles indicating at least local sterilization of tile areas. The findings suggest that minimum time/temperature combination is required for complete sterilization. Microbial analysis of tiles processed at lower temperatures from 130deg C-150deg C at varying times will be discussed, as well as analysis of the bacteria and fungi present on the compactor hardware as a result of exposure to the waste and the surrounding environment. The two organisms inoculated into the waste were among those isolated and identified from the HMC surfaces indicating the possibility of cross contamination.

Hummerick, Mary P.↗
NASA NTRS2018

Preventing Premature Death in the M&S Lifecycle: Lessons Learned from Resurrection and Modernization of a Space System Contamination Model

Models and simulations (M&S) are often developed to meet specific needs and unique requirements for a particular situation. Once the M&S is implemented for a specific case and questions are answered, the M&S may go dormant until a similar need arises again at a later time, perhaps months to years later. Possible modification of the M&S may be required, and issues may arise if the M&S is not well documented, captured, or available. This can severely limit the useful life of the M&S and hinder future development or enhancements. This situation occurred with an M&S tool that had been developed to determine the impact to space system performance due to the presence of molecular contaminant films accumulating on key spacecraft surfaces. The challenges and issues encountered when resurrecting, executing, and modernizing the tool will be presented as a case study. To stay ahead of tomorrow’s challenges, resources to create M&S tools must be utilized efficiently. Lessons learned from this case study will aid M&S developers and users in planning for proper maintenance, transfer, and capture of key M&S tools and knowledge to avoid increased cost, increased development time, and wasted resources for projects relying on M&S.

Seasly, Elaine↗