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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Thermal Protection System P50 Cork Char Response Characterization to Ascent Flight Shear and Heating Environments

NASA’s Space Launch System (SLS) experienced deflagration of the acreage of the Core Stage base heat shield during the Green Run hot-fire test campaigns and Artemis I flight. The burning products from the base heat shield during Green Run hot-fire test operation led to concerns in aerothermal environments and thermal protection system (TPS) performance prior to Artemis I flight. Updated design thermal environments accounting for cork combustion were developed using Green Run measurements and assessed prior to Artemis I, resulting in increased TPS thickness for the base heat shield. This work documents a highly controlled ground test within the NASA Marshall Space Flight Center’s Propulsion Test Branch Hot Gas Facility (HGF) and investigates the P50 cork TPS response due to sensitivity changes in radiative heat rates and surface shear stress. Prior to testing at the HGF, most of the P50 cork panels had a thick layer of char due to the cork combustion process replicated in a thermal vacuum chamber. SLS ascent shear stress and heating rate profile were simulated within the HGF by running the combustion-driven wind tunnel at off-nominal conditions and Mach numbers below 1. This test data provided insight into aerothermal measurements from Artemis I flight as well as informing updated base heating design environments for Artemis II. An in-depth understanding of the TPS P50 cork char response and observations is presented for launch vehicle flight ascent environments.

aerothermodynamics↗
NASA NTRS2007

Radiation Hardened Electronics for Space Environments (RHESE)

Radiation Environmental Modeling is crucial to proper predictive modeling and electronic response to the radiation environment. When compared to on-orbit data, CREME96 has been shown to be inaccurate in predicting the radiation environment. The NEDD bases much of its radiation environment data on CREME96 output. Close coordination and partnership with DoD radiation-hardened efforts will result in leveraged - not duplicated or independently developed - technology capabilities of: a) Radiation-hardened, reconfigurable FPGA-based electronics; and b) High Performance Processors (NOT duplication or independent development).

Keys, Andrew S.↗
NASA NTRS1972

Physiological response in pilot/back-seat man during aerial combat maneuvers in F-4E aircraft.

Comparison of objective/subjective physiological data between the pilot and the back-seat man during training within the G maneuvering envelope. It appears that the psychological requirements for the pilot to be mentally alert and physiologically adapted to a continually changing environment places additional responsibility on him to the extent the physiological signs monitored are indicative of a high stress condition and are increased by a significant amount over the back-seat man who is, in most instances, riding passively.

Leverett, S. D., Jr.↗
NASA NTRS2010

Vibration Response Predictions for Heavy Panel Mounted Components from Panel Acreage Environment Specifications

The development of new launch vehicles in the Aerospace industry often relies on response measurements taken from previously developed vehicles during various stages of liftoff and ascent, and from wind tunnel models. These measurements include sound pressure levels, dynamic pressures in turbulent boundary layers and accelerations. Rigorous statistical scaling methods are applied to the data to derive new environments and estimate the performance of new skin panel structures. Scaling methods have proven to be reliable, particularly for designs similar to the vehicles used as the basis for scaling, and especially in regions of smooth acreage without exterior protuberances or heavy components mounted to the panel. To account for response attenuation of a panel-mounted component due to its apparent mass at higher frequencies, the vibroacoustics engineer often reduces the acreage vibration according to a weight ratio first suggested by Barrett. The accuracy of the reduction is reduced with increased weight of the panel-mounted component, and does not account for low-frequency amplification of the component/panel response as a system. A method is proposed that combines acreage vibration from scaling methods with finite element analysis to account for the frequency-dependent dynamics of heavy panel-mounted components. Since the acreage and mass-loaded skins respond to the same dynamic input pressure, such pressure may be eliminated in favor of a frequency-dependent scaling function applied to the acreage vibration to predict the mass-loaded panel response. The scaling function replaces the Barrett weight ratio, and contains all of the dynamic character of the loaded and unloaded skin panels. The solution simplifies for spatially uncorrelated and fully correlated input pressures. Since the prediction uses finite element models of the loaded and unloaded skins, a rich suite of response data are available to the design engineer, including interface forces, stress and strain, as well as acceleration and displacement. An extension of the method is also developed to incorporate the effect of a local protuberance near a heavy component. Acreage environments from traditional scaling methods with and without protuberance effects serve as the basis for the extension. Authors:

Harrison, Phillip↗
NASA NTRS1992

Environmental effects on long term behavior of composite laminates

Model equations are presented for approximate methods simulating the long-term behavior of composite materials and structures in hot/humid service environments. These equations allow laminate property upgradings with time, and can account for the effects of service environments on creep response. These methodologies are illustrated for various individual and coupled temperature/moisture, longitudinal/transverse, and composite material type cases. Creep deformation is noted to rise dramatically for cases of matrix-borne, but not of fiber-borne, loading in hot, humid environments; the coupled influence of temperature and moisture is greater than a mere combination of their individual influences.

Singhal, S. N.↗
NASA NTRS1974

Fluid dynamics and kinematics of molten metals in the low-gravity environment of Skylab

The response of molten metals to mechanical and thermal driving forces in nominal and microgravity is analyzed both theoretically and experimentally. The magnitude and transient behavior of internal fluid circulations, surface deformations, and globule trajectories and their effects on solidification in the Skylab electron beam sphere forming and metals melting experiments are determined. The theoretical approach consists of dimensional analysis of the governing differential equations. Experimental aspects include evaluation of specimens from terrestrial, KC-135 research aircraft, and actual Skylab tests and analysis of high speed movies taken during the melting processes. Several gravity variations and gravity independent results were successfully predicted based on expected differences and similarities in fluid dynamics.

Bourgeois, S. V.↗
NASA NTRS1975

Response of selected microoganisms to experimental planetary environments

A microbial population profile of mixed Cape Canaveral soil samples is presented. During this investigation a few organisms were isolated which exhibit the ability to grow at 3 C, 32 C, and 55 C. Growth curves are shown for three of these isolates, one of which grows extremely well at all three temperatures. Also included are studies dealing with growth of soil populations at zero and subzero temperatures. Results indicate growth at 0 C and -5 C, but not at 15 C or -65 C. The effect of storage temperature on dry soil is presented, and results show that psychrophilic populations decrease when soil is stored at room temperature, but do not decrease when soil is stored at -65 C. Results of an experiment with the simulated Martian environment are presented and indicate that nonsporeforming rods, sporeforming rods, and cocci can reproduce in the simulated environment when nutrients and moisture are supplied. The sporeforming rods are the predominant suvivors when dry soil is subjected to this environment.

Foster, T. L.↗
NASA NTRS1976

Response of selected microorganisms to experimental planetary environments

The anaerobic utilization of phosphite or phosphine and the significance of this conversion to potential contamination of Jupiter were investigated. A sporeforming organism was isolated from Cape Canaveral soil which anaerobically converts hypophosphite to phosphate. This conversion coincides with an increase in turbidity of the culture and with phosphate accumulation in the medium. Investigations of omnitherms (organisms which grow over a broad temperature range, i.e. 3 -55 C were also conducted. The cellular morphology of 28 of these isolates was investigated, and all were demonstrated to be sporeformers. Biochemical characterizations are also presented. Procedures for replicate plating were evaluated, and those results are also presented. The procedures for different replicate-plating techniques are presented, and these are evaluated on the basis of reproducibility, percentage of viable transfer, and ease of use. Standardized procedures for the enumeration of microbial populations from ocean-dredge samples from Cape Canaveral are also presented.

Foster, T. L.↗
NASA NTRS1976

Response of selected microorganisms to experimental planetary environments

Results are presented on the anaerobic conversion of phosphite to phosphate. It is demonstrated that in the presence of both phosphite and hypophosphite, the phosphite is the preferred phosphorous source. An investigation in which P-32 labeled hypophosphite was added to the basal medium demonstrates that the labeled hypophosphite was incorporated into the metabolic reactions of the cell. Other data show that as cell growth occurs, the phosphite and/or hypophosphite levels decrease. The Bacillus sp. capable of anaerobic utilization of phosphite was isolated from Cape Canaveral soil samples, and it is partially characterized. Also included are continued investigations of omnitherms. The data presented show that some of these possess significant resistance to the Viking dry-heat cycle, and that they retain their omnithermic characteristic after recovery from the heat cycle. Other physiological characteristics of these isolates are also presented. It is demonstrated that omnitherms can be isolated from Cape Canaveral soil.

Foster, T. L.↗
NASA NTRS1977

Response of Selected Microorganisms to Experimental Planetary Environments

Results of studies in anaerobic phosphorus metabolism are presented. Specific topics discussed include: (1) anaerobic utilization of PH3; (2) reduction of phosphate or phosphite; (3) isolation of organisms which utilize phosphite or phosphate anaerobically as a final hydrogen acceptor; and (4) the toxicity of PH3 to the organisms. Techniques of anaerobic microbiology associated with space hardware were also studied. These include: (1) the Brewer anaerobe jar/GasPak system; (2) a new procedure to grow aerobes and anaerobes simultaneously; (3) a culture medium to differentiate oblagate from facultative anaerobes; and (4) a procedure to quantitate O2 sensitivity of anaerobes.

Foster, T. L.↗
NASA NTRS1979

Acoustic response of thin film windows in the environment of an Atlas-Centaur launch

An exhaustive design development study was performed to correlate the survivability of thin film to various parameters. Film material properties, film thicknesses, unsupported window areas, window aspect ratios, film/frame transitions, film reinforcing techniques, and material grain orientations were all considered. Several thin films were tested to acoustical loads which are expected during an Atlas-Centaur launch of the High Energy Astronomy Observatory Satellites (HEAO)

Mastronardi, R.↗
NASA NTRS1981

Response of selected microorganisms to experimental planetary environments

Anaerobic and aerobic sporeformers and non-sporeformers were cultivated anaerobically in nutrient media under various pressures (up to 1800 psi) of pure H2, CH4, NH3, and H2S. Viability assays were performed periodically to determine growth, survival, or spore survival. Hydrogen up to 1800 psi demonstrated little or no suppression of growth with the possible exception of Bacillus coagulans at 1800 psi. The obligate anaerobes grew very well. Under CH4 the obligate anaerobes again exhibited the most prolific growth, whereas the facultative anaerobes grew well except under higher pressures. Ammonia at low pressure was extremely toxic to all test organisms. At 100 psi all populations were killed within 24 hours except Staphylococcus aureus which survived for 72 hours and the Bacillus spp. which produced a surviving population of approximately 10,000 spores/ml. All populations in H2S were killed within 24 to 48 hours except Proteus mirabilis which decreased to 100 cells/ml and the Bacillus spp. Spore survival studies of two months duration demonstrated that B. coagulans and B. pumilus survived under all experimental conditions. Clostridium novyi type B and C. sporogenes were killed rapidly in NH3 and H2S and demonstrated no sporulation.

Foster, T. L.↗
NASA NTRS1992

The response of the SSM/I to the marine environment. I - An analytic model for the atmospheric component of observed brightness temperatures

A detailed parameterization is developed for the contribution of the nonprecipitating atmosphere to the microwave brightness temperatures observed by the Special Sensor Microwave/Imager (SSM/I). The atmospheric variables considered include the viewing angle, the integrated water vapor amount and scale height, the effective tropospheric lapse rate and near-surface temperature, the total cloud liquid water, the effective cloud height, and the surface pressure. The dependence of the radiative variables on meteorological variables is determined for each of the SSM/I frequencies 19.35, 22.235, 37.0, and 85.5 GHz, based on the values computed from 16,893 maritime temperature and humidity profiles representing all latitude belts and all seasons. A comparison of the predicted brightness temperatures with brightness temperatures obtained by direct numerical integration of the radiative transfer equation for the radiosonde-profile dataset yielded rms differences well below 1 K for all four SSM/I frequencies.

Petty, Grant W.↗
NASA NTRS1994

The response of the SSM/I to the marine environment. Part 2: A parameterization of the effect of the sea surface slope distribution on emission and reflection

Based on a geometric optics model and the assumption of an isotropic Gaussian surface slope distribution, the component of ocean surface microwave emissivity variation due to large-scale surface roughness is parameterized for the frequencies and approximate viewing angle of the Special Sensor Microwave/Imager. Independent geophysical variables in the parameterization are the effective (microwave frequency dependent) slope variance and the sea surface temperature. Using the same physical model, the change in the effective zenith angle of reflected sky radiation arising from large-scale roughness is also parameterized. Independent geophysical variables in this parameterization are the effective slope variance and the atmospheric optical depth at the frequency in question. Both of the above model-based parameterizations are intended for use in conjunction with empirical parameterizations relating effective slope variance and foam coverage to near-surface wind speed. These empirical parameterizations are the subject of a separate paper.

Petty, Grant W.↗
NASA NTRS2009

Wireless Fluid-Level Sensors for Harsh Environments

Magnetic-field-response sensors have been developed for use in measuring levels of fluids under extreme conditions. The sensors work without wire connections or direct physical contact with power sources, microprocessors, data-acquisition equipment, or electrical circuitry. For fuel-level sensors, the absence of wire connections offers an important safety advantage in elimination of potential ignition sources.

Woodward, Stanley E.↗