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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Long term microparticle impact fluxes on LDEF determined from optical survey of Interplanetary Dust Experiment (IDE) sensors

Many of the IDE metal-oxide-silicon (MOS) capacitor-discharge impact sensors remained active during the entire Long Duration Exposure Facility (LDEF) mission. An optical survey of impact sites on the active surfaces of these sensors has been extended to include all sensors from the low-flux sides of LDEF (i.e. the west or trailing side, the earth end, and the space end) and 5-7 active sensors from each LDEF's high-flux sides (i.e. the east or leading side, the south side, and the north side). This survey was facilitated by the presence of a relatively large (greater than 50 micron diameter) optical signature associated with each impact site on the active sensor surfaces. Of the approximately 4700 impacts in the optical survey data set, 84% were from particles in the 0.5 to 3 micron size range. An estimate of the total number of hypervelocity impacts on LDEF from particles greater than 0.5 micron diameter yields a value of approximately 7 x 10(exp 6). Impact feature dimensions for several dozen large craters on MOS sensors and germanium witness plates are also presented. Impact fluxes calculated from the IDE survey data closely matched surveys of similar size impacts (greater than or equal to 3 micron diameter craters in Al, or marginal penetrations of a 2.4 micron thick Al foil) by other LDEF investigators. Since the first year IDE data were electronically recorded, the flux data could be divided into three long term time periods: the first year, the entire 5.8 year mission, and the intervening 4.8 years (by difference). The IDE data show that there was an order of magnitude decrease in the long term microparticle impact flux on the trailing side of LDEF, from 1.01 to 0.098 x 10(exp -4) m(exp 2)/s, from the first year in orbit compared to years 2-6. The long term flux on the leading edge showed an increase from 8.6 to 11.2 x 10(exp -4) m(exp -2)/s over this same time period. (Short term flux increases up to 10,000 times the background rate were recorded on the leading side during LDEF's first year in orbit.) The overall east/west ratio was 44, but during LDEF's first year in orbit the ratio was 8.5, and during years 2-6 the ratio was 114. Long term microparticle impact fluxes on the space end decreased from 1.12 to 0.55 x 10(exp -4) m(exp -2)/s from the first year in orbit compared to years 2-6. The earth end showed the opposite trend with an increase from 0.16 to 0.38 x 10(exp -4) m(exp -2)/s. Fluxes on rows 6 and 12 decreased from 6.1 to 3.4 and 6.7 to 3.7 x 10(exp -4) m(exp -2)/s, respectively, over the same time periods. This resulted in space/earth microparticle impact flux ratios of 7.1 during the first year and 1.5 during years 2-6, while the south/north, space/north and space/south ratios remained constant at 1.1, 0.16 and 0.17, respectively, during the entire mission. This information indicates the possible identification of long term changes in discrete microparticle orbital debris component contributions to the total impact flux experienced by LDEF. A dramatic decrease in the debris population capable of striking the trailing side was detected that could possibly be attributed to the hiatus of western launch activity experienced from 1986-1989. A significant increase in the debris population that preferentially struck the leading side was also observed and could possibly be attributed to a single breakup event that occurred in September of 1986. A substantial increase in the microparticle debris population that struck the earth end of LDEF, but not the space end, was also detected and could possibly be the result of a single breakup event at low altitude. These results point to the importance of including discrete orbital debris component contribution changes in flux models in order to achieve accurate predictions of the microparticle environment that a particular spacecraft will experience in earth orbit. The only reliable, verified empirical measurements of these changes are reported in this paper. Further time-resolved in-situ measurements of these debris populations are needed to accurately assess model predictions and mitigation practices.

Simon, C. G.↗
NASA NTRS2016

Advances in Rodent Research Missions on the International Space Station

A research platform for rodent experiment on the ISS is a valuable tool for advancing biomedical research in space. Capabilities offered by the Rodent Research project developed at NASA Ames Research Center can support experiments of much longer duration on the ISS than previous experiments performed on the Space Shuttle. NASAs Rodent Research (RR)-1 mission was completed successfully and achieved a number of objectives, including validation of flight hardware, on-orbit operations, and science capabilities as well as support of a CASIS-sponsored experiment (Novartis) on muscle atrophy. Twenty C57BL6J adult female mice were launched on the Space-X (SpX) 4 Dragon vehicle, and thrived for up to 37 days in microgravity. Daily health checks of the mice were performed during the mission via downlinked video; all flight animals were healthy and displayed normal behavior, and higher levels of physical activity compared to ground controls. Behavioral analysis demonstrated that Flight and Ground Control mice exhibited the same range of behaviors, including eating, drinking, exploratory behavior, self- and allo-grooming, and social interactions indicative of healthy animals. The animals were euthanized on-orbit and select tissues were collected from some of the mice on orbit to assess the long-term sample storage capabilities of the ISS. In general, the data obtained from the flight mice were comparable to those from the three groups of control mice (baseline, vivarium and ground controls, which were housed in flight hardware), showing that the ISS has adequate capability to support long-duration rodent experiments. The team recovered 35 tissues from 40 RR-1 frozen carcasses, yielding 3300 aliquots of tissues to distribute to the scientific community in the U.S., including NASAs GeneLab project and scientists via Space Biology's Biospecimen Sharing Program Ames Life Science Data Archive. Tissues also were distributed to Russian research colleagues at the Institute for Biomedical Problems. The expression levels of select genes including albumin, catalase, GAPDH, HMGCoA Reductase, and IGF1 were determined using RNA isolated from the livers by qPCR and no significant differences by one factor ANOVA were found between flight and ground control groups. In addition, some of the liver samples were analyzed for transcriptomic, epigenomic and proteomic profiles; some of the data sets are now available to the scientific community through GeneLabs open science data website. A second long duration mission, Rodent Research-2 (RR-2) was completed on the ISS in 2015; 20 female C57BL6J mice were successfully maintained on the ISS for various durations, with the last group of 5 animals living on-orbit for 54 days. Furthermore, we continue to expand the ISSs capabilities by introducing new on-orbit technologies including blood collection and separation, bone densitometry scanning, muscle grip strength and anesthesia with recovery. In addition, series of ground-based verification testing to fly male mice and increase the total number of mice on-orbit from 20 to 40. Subsequent missions will provide the capability to return live mice from the ISS animals to evaluate recovery on Earth, further expanding operational and science capabilities of the RR project on the ISS.

Choi, S. Y.↗
NASA NTRS1969

Beam profiles measured with thermoluminescent dosimeters

Beam profilometer, using thermoluminescent dosimeters, gives a quantitative and qualitative representation of the focus of an external protron beam of a synchrotron. The total number of particles in the beam, particle distribution, and the shape of the beam are determined.

Lucks, H.↗
NASA NTRS1971

Future Possibilities in spacecraft ranging and Doppler systems

The structure of spacecraft tracking radar, and range and Doppler measurements, are discussed. Ranging can be used in conjunction with Doppler to determine the total number of charged particles on the radio path. Ranging can also be employed as the primary data type in determining certain kinds of orbits. The basic configuration of the ranging and Doppler system is considered. Inherent limitations on its accuracy with respect to the oscillator, transponder, ground equipment, signal to noise ratio, and general operation are noted.

Easterling, M.↗
NASA NTRS1972

User's manual for the Simulated Life Analysis of Vehicle Elements (SLAVE) model

The simulated life analysis of vehicle elements model was designed to perform statistical simulation studies for any constant loss rate. The outputs of the model consist of the total number of stages required, stages successfully completing their lifetime, and average stage flight life. This report contains a complete description of the model. Users' instructions and interpretation of input and output data are presented such that a user with little or no prior programming knowledge can successfully implement the program.

Paul, D. D., Jr.↗
NASA NTRS1972

Effect of carbide size, area, density on rolling-element fatigue

A carbide parameter that can be used to predict rolling element fatigue life was developed.The parameter is based on a statistical life analysis and incorporates the total number of particles per unit area, particle size, and percent carbide area. These were determined from quantimet image analyzing computer examinations of random samples selected from eight lots of material previously tested in rolling fatigue. The carbide parameter is independent of chemical composition, heat treatment, and hardening mechanism of the materials investigated.

Chevalier, J. L.↗
NASA NTRS1971

Integrated operations/payloads/fleet analysis. Volume 1: Summary, study overview

The preparation of payload input data for analysis, and the capture and cost analyses are described for the current fleet, a low cost expendable fleet, and the space shuttle/space tug fleet. The data preparation consisted of formatting, extending, and correcting the input data which were broken down in terms of satellite gross weight. The results of the analyses indicate a significant reduction in the required total number of new payload units for the space shuttle/space tug fleet. Another result is that 26% of the payloads for the new low cost expendable fleet and 26% for the space shuttle/space tug fleet are of low cost payload designs.

Source record↗
NASA NTRS1972

A new criterion for predicting rolling-element fatigue lives of through-hardened steels

A carbide factor was derived based upon a statistical analysis which related rolling-element fatigue life to the total number of residual carbide particles per unit area, median residual carbide size, and percent residual carbide area. An equation was experimentally determined which predicts material hardness as a function of temperature. The limiting temperatures of all of the materials studied were dependent on initial room temperature hardness and tempering temperature. An equation was derived combining the effects of material hardness, carbide factor, and bearing temperature to predict rolling-element bearing life.

Chevalier, J. L.↗
NASA NTRS1972

Energy calibration of a cosmic ray ionization spectrometer

The NASA/GSFC high energy cosmic ray experiment was calibrated during the summer of 1970 using protons and pions with energies from 9.3 GeV to 17.6 GeV. The best measure found for the energy E of an incoming primary particle is sigma I, the total number of ionizing particles observed in the instrument, summed over the various iron modules. The resolution in the calibration energy range is about + or - 30 percent (s.d.) over a wide range of incident angles and positions. The calibration function may be parameterized as e = sigma I/K, where K is predominantly a function of the location of the first interaction and the trajectory of the incoming particle.

Whiteside, H.↗
NASA NTRS1972

Low intensity H-beta emission from the interstellar medium

Pulsar pulse dispersions and low-frequency absorption of galactic and extragalactic radio sources strongly suggest that the interstellar medium is much more ionized than previously assumed. The search was confined to directions near pulsars because of the additional information provided by the dispersion measure which gives the total number of electrons along the line of sight to the pulsar. Of the four directions in which observations were made, an emission line appears to be present in at least two and possibly three directions. The data are shown from a low galactic latitude direction near the Crab Nebula pulsar. The observing direction was about 9 arcmin off the Crab with the field of view of about 1.5 arcmin. The number of counts was plotted versus the local standard of rest velocity and local standard wavelength of H-beta.

Reynolds, R. J.↗
NASA NTRS1971

Petrological character of the Luna 16 sample from Mare Fecunditatis.

A total number of 1858 lithic and vitreous fragments from the Luna 16 core-tube sample are classified. The fragments were taken from soil fractions ranging in size from 150 to 425 microns at levels A and G. No important differences are observed between the proportions of particle types in levels A and G, nor between the soils of Luna 16 and those from the Apollo 11 landing site in the nearby Mare Tranquillitatis.

Wood, J. A.↗
NASA NTRS1971

Molecular configuration and pyrolysis reactions of phenolic-novolaks.

Description of a statistical method for characterizing the structure of an average phenolic-novolak prepolymer molecule in terms of the total number of phenolic nuclei that compose the molecule and the number of these nuclei that are pendent. It is only necessary to resort to experimental pyrolysis to evaluate the thermokinetic parameters for pyrolysis for the ablator. In addition, the fraction of phenolic involved in the major pyrolysis reactions can be estimated in terms of the parameters previously evaluated. It is shown that the overlapping reactions which occur during pyrolysis of a phenolic-novolak can be resolved by pyrolyzing samples with different extents of cure. It is then possible to determine the kinetic parameters for pyrolysis for the major reactions by well-known methods which often fail when reactions are not well resolved.

Winkler, E. L.↗
NASA NTRS1972

Multispectral discrimination of possible Martian surface constituents.

In the 1970s attempts will be made to soft-land scientific instruments on the surface of Mars. The question of the employment of several spectral bands to improve discrimination is investigated. The studies conducted are concerned with the development of a technique for selecting color bands for a lander imaging system. Other study objects include the investigation of certain solid state detectors and the determination of the feasibility of minimizing the total number of telemetry bits from the lander by various means.

Klemas, V.↗
NASA NTRS1972

The contributions of Ranger photographs to understanding the geology of the moon

Vidicon photographs returned to earth by Rangers 7, 8, and 9 in 1964 and 1965 were used to study the details of lunar geologic units previously recognized from earth-based telescopic photographs and to make geologic maps at a variety of scales. The photographs from each mission changed continuously in scale as the spacecraft approached impact. The final frames had resolutions some 1,000 times better than the best earthbased photographs. Lunar stratigraphic units mapped at a scale of 1:1,000,000 displayed, at these larger scales, differences in properties and, possibly, in ages, but a clear-cut stratigraphic succession of subunits was not apparent. The plains-forming materials in both terra and mare were divisible into units mainly on the basis of the differences in the total number of superposed craters and in the relative number of craters of various morphologic types.

Trask, N. J.↗
NASA NTRS1972

A new criterion for predicting rolling-element fatigue lives of through-hardened steels.

A carbide factor was derived based upon a statistical analysis which related rolling-element fatigue life to the total number of residual carbide particles per unit area, median residual carbide size, and percent residual carbide area. An equation was empirically determined which predicts material hardness as a function of temperature. The limiting temperatures of all of the materials studied were dependent on initial room temperature hardness and tempering temperature. An equation was derived combining the effects of material hardness, carbide factor, and bearing temperature to predict rolling-element bearing life.

Chevalier, J. L.↗
NASA NTRS1973

Optimum detection of an optical image on a photoelectric surface.

The image-detecting performance of an optimum counting detector is compared with that of a threshold detector and that of a detector basing its decisions on the total number of photoelectrons from a finite area of the image. The illuminance of the image is assumed to have a Gaussian spatial distribution. The optimum detector works with the pristine datum (and not with the photoelectric response) which is the spatiotemporal electromagnetic field at the aperture of the observing optical instrument. It is shown that little is to be gained by using details of the illuminance distribution beyond the crude knowledge of its breadth as embodied in a simple counter of emitted photoelectrons. All three detectors exhibit accordingly about the same reliability.

Helstrom, C. W.↗
NASA NTRS1973

Mariner 9 infrared interferometer spectrometer (IRIS) reduced data records documentation

The Mariner 9 spacecraft was successfully inserted into orbit around Mars. One of the five instruments on board, an infrared interferometer spectrometer is used to record the thermal emission spectrum of Mars between 200 and 2000 cm/1. The spatial resolution for vertical viewing is a circular area of approximately 110 km diameter for a periapsis height of 1400 km. The total number of calibrated spectra included in the final data set is 21167. The final calibrated thermal emission spectra contained in the reduced data records are reported.

Source record↗