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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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Acrylic film contains screeing agent filtering ultraviolet radiation up to 380 nanometers in wavelength but passes other components of Sunlight. Film used to protect such materials as rubber and plastics degraded by ultraviolet light. Used as protective cover on outdoor sheets or pipes made of such materials as polyethylene or polypropylene and on solar cells.
Engineering study guides design and monitoring of lightning protection. Design studies for project are collected in 150-page report, containing wealth of information on design of lightning protection systems and on instrumentation for monitoring current waveforms of lightning strokes.
The increased bandwidth and sensitivity of the DSN maser-based receiver systems along with the increase in worldwide microwave spectrum usage dictated the need for employing additional measures to protect these systems from RFI (radio frequency inerference). Both in-band and out-of-band microwave signals at the input of the Deep Space Network (DSN) traveling wave masers (TWM) can adversely affect the maser performance in a variety of ways. Filters fabricated from superconducting materials operating below their superconducting transition temperature (Tc) possess the most potential for providing the necessary RFI protection without degrading the system performance.
The laboratory testing of a large number of films and liquid coatings for aircraft drag reduction and erosion protection has led to the identification of elastomeric polyurethanes, which fulfil smoothness, durability and protection requirements while being easily applied to large, compound-curvature areas with standard spray equipment. It was found that an epoxy primer produced a stronger bond between coating and substrate than a wash primer. A drag-reduction value of 0.2% was achieved with a commercially-available elastomeric polyurethane.
The provision of heat protection for various elements of space flight apparata has great significance, particularly in the construction of manned transport vessels and orbital stations. A popular explanation of the methods of heat protection in rocket-space technology at the current stage as well as in perspective is provided.
An analytical method was developed for predicting minimum flow rates required to provide anti-ice protection with a porous leading edge fluid ice protection system. The predicted flow rates compare with an average error of less than 10 percent to six experimentally determined flow rates from tests in the NASA Icing Research Tunnel on a general aviation wing section.
Five volunteer subjects were tested for acceleration tolerance under eight different experimental conditions representing relaxed and unprotected tolerance and tolerance with all possible combinations of the anti-G suit, and M-1 maneuver, and supination in a PALE seat. The individual and combined effects of the various acceleration protective techniques were examined as they related to various models for acceleration protection, and the data revealed no statistically significant deviations from a simple additive model. The apparent net additivity was interpreted as resulting from a combination of additive, synergistic, and overlapping mechanisms.
A policy on the protection of extraterrestrial bodies from contamination by terrestrial microorganisms and organic constituents that might interfere with studies of chemical and biological evolution on those bodies is proposed which is based on new information gained in planetary exploration over the past decade. The proposed policy overcomes the difficulties associated with the uncertainties in parameters and the rigid requirements of the current probabilistic approach by eliminating the general quantitative guideline and by calling for the implementation of planetary protection procedures for space projects by exception, depending on target planet and type of encounter. The impact of the proposed policy on the implementation of future space missions is illustrated for the Galileo Jupiter mission, a cometary mission, the Saturn Orbiter with Twin Probes, and a Mars Surface Sample Return Mission, and procedures which may lead to the eventual adoption of the policy are noted.
An analytical study was performed to investigate the excessive heating in the tile to tile gaps of the Shuttle Orbiter Thermal Protection System due to stepped tiles. The excessive heating was evidence by visible discoloration and charring of the filler bar and strain isolation pad that is used in the attachment of tiles to the aluminum substrate. Two tile locations on the Shuttle orbiter were considered, one on the lower surface of the fuselage and one on the lower surface of the wing. The gap heating analysis involved the calculation of external and internal gas pressures and temperatures, internal mass flow rates, and the transient thermal response of the thermal protection system. The results of the analysis are presented for the fuselage and wing location for several step heights. The results of a study to determine the effectiveness of a half height ceramic fiber gap filler in preventing hot gas flow in the tile gaps are also presented.
The Shuttle orbiter themal protection system (TPS) incorporates ceramic reusable surface insulation tiles bonded to the orbiter substructure through a strain isolation pad. Densification of the bonding surface of the tiles increases the static strength of the tiles. The densification proces does not, however, necessarily lead to an equivalent increase in fatigue strength. Investigation of the expected lifetime of densified tile TPS under both sinusoidal loading and random loading simulating flight conditions indicates that the strain isolation pads are the weakest components of the TPS under fatigue loading. The felt pads loosen under repetitive loading and, in highly loaded regions, could possibly cause excessive step heights between tiles causing burning of the protective insulation between tiles. A method of improving the operational lifetime of the TPS by using a strain isolation pad with increased stiffness is presented as is the consequence of the effect of increased stiffness on the tile inplane strains and transverse stresses.
A hexagonal protective and high temperature resistant system for the Space Shuttle Orbiter consists of a multiplicity of pockets formed by hexagonally oriented spacer bars secured on the vehicle substructure. A packing of low density insulating batt material 18 in each pocket, and a thin protective panel of laterally resilient advanced carbon-carbon material surmounting the peripherals bars and packing. Each panel has three stepped or offset lips on contiguous edges. At the center of each pocket is a fully insulated stanchion secured to and connecting the substructure and panel for flexing the panel toward the substructure and thereby prestressing the panel and forcing the panel edges firmly against the spacer bars.
The heat resistant, protective glove is made up of first and second shell sections which define a palm side and a backside, respectively. The first shell section is made of a twill wave fabric of a temperature-resistant aromatic polyamide fiber. The second shell section is made of a knitted fabric of a temperature-resistant aromatic polyamide fiber. The first and second shell sections are secured to one another, e.g., by sewing, to provide the desired glove configuration and an opening for insertion of the wearer's hand. The protective glove also includes a first liner section which is secured to and overlies the inner surface of the first shell section and is made of a felt fabric of a temperature-resistant aromatic polyamide fiber and has a flame resistant, elastomenic coating on the surface facing and overlying the inner surface of the first shell section.
Kapton polyimide oxidizes at significant rates (4.3x10(-24) gram/incident oxygen atom) when exposed in low Earth orbit to the ram atomic oxygen flux. Ion beam sputter deposited thin films of Al2O3 and SiO2 as well as a codeposited mixture of predominantly SiO2 with a small amount of polytetrafluoroethylene were evaluated and found to be effective in protecting Kapton from oxidation in both laboratory plasma ashing tests as well as in space on board shuttle flight STS-8. A protective film of or = 96 percent SiO2 and or = 4 percent polytetrafluoroethylene was found to be very flexible compared to the pure metal oxide coatings and resulted in mass loss rates that were 0.2 percent of that of the unprotected Kapton. The optical properties of Kapton for wavelengths investigated between 0.33 and 2.2 microns were not significantly altered by the presence of the coatings or changed by exposure of the coated Kapton to the low Earth orbital ram environment.
The grounding and fault protection aspects of large photovoltaic power systems are studied. Broadly, the overlapping functions of these two plant subsystems include providing for the safety of personnel and equipment. Grounding subsystem design is generaly governed by considerations of personnel safety and the limiting of hazardous voltages to which they are exposed during the occurrence of a fault or other misoperation of equipment. A ground system is designed to provide a safe path for fault currents. Metal portions of the modules, array structures, and array foundations are used as a part of the ground system, provided that they and their interconnection are designed to be suitably reliable over the life of the plant. Several alternative types of fault protection and detection equipment are designed into the source circuits and dc buses feeding the input terminals of the subfield power conditioner. This design process requires evaluation of plausible faults, equipment, and remedial actions planned to correct faults. The evaluation should also consider life cycle cost impacts.
Mylar strips, 2.5 microns thick, uncoated and coated with 50A, 100A and 200A of Al, Pd, and Au/Pd were exposed on STS-5 in order to measure the erosion of mylar and to test means of protecting thin plastic foils commonly used for space experiments in low earth orbit. Analysis by optical microscopy, SEM and STEM investigation, EDX measurements, FTIR spectroscopy and weight loss measurements showed that while up to 75 percent of the uncoated mylar was eroded during exposure, thin coatings of the above metals can protect mylar for integrated oxygen-fluxes of at least 10 to the 21st atoms/sq cm.
Short-circuit current provides minimum memory power. Protective circuit includes dc-to-dc converter that supplies keep-alive voltage to memories when short circuit occurs in any of system loads. Converter powered by lowvoltage across two of three series diodes generated by short-circuit bus current. Relay switch is in open (short-circuit-detected) position. Protective circuit useful wherever necessary to improve reliability of volatile memories or other circuits that must not lose power.
Uncomplicated, inexpensive intercom protects head, face, and hearing. Adaptation of highly suitable stock helmet and face shield unit to stock intercom headset provided ideal unit, allowing wearer total use of hands and body while protecting head, face, and hearing. Unit allows wearer to work effectively, efficiently, and safely while communicating from remote areas that require special precautions. Total cost of fabricating unit, using stock parts and including labor, less than $100.
Proposed garment material protects wearer from poisonous chemicals, bacteria, and radioactive particulates. Garment allows heat, moisture, and carbon dioxide to pass from inside to outside so wearer remains comfortable. Garment made of cotton fabric on which thin layer of polyacrylate rubber is deposited by calendering or spraying. Lighter and cooler than existing protective garments. Polyacrylate rubber selected for garment material because it transmits water vapor and carbon dioxide at high rates.