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NASA NTRS1975

The total and spectral solar irradiance and its possible variations

The present status of knowledge of the total and spectral irradiance of the sun is briefly reviewed. Currently accepted values of the solar constant and the extraterrestrial solar spectral irradiance are presented along with a discussion of how they were derived. Data on the variability of the solar constant are shown to be conflicting and inconclusive. Some of the alleged sun-weather relationships are cited in support of the need of knowing more precisely the variations in total and spectral solar irradiance. An overview of a solar monitoring program is discussed, with special emphasis on the Solar Energy Monitor in Space experiment which was proposed for several spacecraft missions. It is a combination of a solar constant detector and a prism monochromator. The determination of absolute values and the possible variations of the total and spectral solar irradiance, from measurements outside of the atmosphere is discussed.

Thekaekara, M. P.↗

NASA NTRS1976

Solar irradiance - Total and spectral and its possible variations

The present status of our knowledge of the total and spectral irradiance of the sun is briefly reviewed. The currently accepted NASA/ASTM standard values of the solar constant and the extraterrestrial solar spectral irradiance are presented. The uncertainties in these values are relatively high. Data on the variability of the solar constant are conflicting and inconclusive. The variability of solar spectral irradiance is almost totally unknown and unexplored. Some alleged sun-weather relationships are cited in support of the need to know more precisely the variations in total and spectral solar irradiance. An overview of the solar monitoring program of NASA is presented, with special emphasis on the Solar Energy Monitor in Space (SEMIS) experiment which has been proposed for several spacecraft missions. The monitor is a combination of a solar-constant detector and a prism monochromator.

Thekaekara, M. P.↗

NASA NTRS1977

Aerodynamic characteristics of a 1/6-scale powered model of the rotor systems research aircraft

A wind-tunnel investigation was conducted to determine the effects of the main-rotor wake on the aerodynamic characteristics of the rotor systems research aircraft (RSRA). For the investigation, a 1/6-scale model with a four-blade articulated main rotor was used. Tests were conducted with and without the main rotor. Both the helicopter and the compound helicopter were tested. The latter configuration included the auxiliary thrust engines and the variable-incidence wing. Data were obtained over ranges of angle of attack, angle of sideslip, and main-rotor collective pitch angle at several main-rotor advance ratios. Results are presented for the total loads on the airframe as well as the loads on the rotor, the wing, and the tail. The results indicated that without the effect of the rotor wake, the RSRA had static longitudinal and directional stability and positive effective dihedral. With the effect of the main rotor and its wake, the RSRA exhibited longitudinal instability but retained static directional stability and positive effective dihedral.

Mineck, R. E.↗

NASA NTRS1977

Recent research on aerodynamic characteristics of fighter configurations during spins

The NASA Langley Research Center is currently conducting a stall/spin research program to define fighter aerodynamics applicable during developed spins and to develop analytical methods to use such measured aerodynamics for theoretically calculating spin motions. Some static, forced-oscillation and continuous rotation aerodynamic data have been measured for several current fighter models at developed spin angles of attack. The paper discusses these aerodynamic data and illustrates both the extremely nonlinear dependence of such data on several variables and the correlation that exists between the three types of measured aerodynamics. The current analytical methods for using these aerodynamics to calculate spin motions are discussed and correlated with experimentally obtained spins.

Anglin, E. L.↗

NASA NTRS1978

Analysis of global oceanic rainfall from microwave data

A Global Rainfall Atlas was prepared from Nimbus 5 ESMR data. The Atlas includes global oceanic rainfall maps based on weekly, monthly and seasonal averages, complete through the end of 1975. Similar maps for 1973 and 1974 were studied. They reveal several previously unknown areas of enhanced rainfall and preliminary data on interannual variability of oceanic rainfall.

Rao, M.↗

NASA NTRS1976

The Seasat surface truth experiments

A surface truth program for Seasat A is formulated in two phases: pre- and post-launch. The pre-launch phase (which includes the Marineland experiments, the JONSWAP-75 experiment, the West Coast experiment, and the altimeter experiment) is designed to provide data from aircraft over instrumented ocean sites during desirable geophysical events. The objective is to gather sufficient data for the development of algorithms which transfer space data into geophysical variables useful for applications. In the post-launch phase, the surface truth program is designed to verify and improve the algorithms developed in the pre-launch phase and also to evaluate the performance of spaceborne sensors.

Shemdin, O. H.↗

NASA NTRS1977

Observed differences in learning ability of heart rate self-regulation as a function of hypnotic susceptibility

Three groups of eight male and female subjects (aged 20-27 yr) categorized by low and high hypnotic susceptibility were taught to control their heart rates by means of an appropriate autogenic therapy/biofeedback technique. The experimental groups were trained by autogenic therapy and biofeedback, while the control group received only biofeedback. Significant differences are observed in all psychological test scores between subjects of high and low hypnotic susceptibility. The results confirm that (1) there are qualitative and quantitative differences between the performance of individuals with high and low hypnotic susceptibility; (2) interindividual-variability tests yield data relevant to individual performance in visceral learning tasks; (3) the combined autogenic therapy/biofeedback/verbal feedback technique is suitable for conditioning large stable autonomic responses in humans; and (4) this kind of conditioning is effective in eliminating or alleviating physiological reactions to some environmental stressors.

Cowings, P. S.↗

NASA NTRS1978

Anthropometry

Data on body-size measurement are presented to aid in spacecraft design. Tabulated dimensional anthropometric data on 59 variables for 12 selected populations are given. The variables chosen were those judged most relevant to the manned space program. A glossary of anatomical and anthropometric terms is included. Selected body dimensions of males and females from the potential astronaut population projected to the 1980-1990 time frame are given. Illustrations of drawing-board manikins based on those anticipated body sizes are included.

Mcconville, J. T.↗

NASA NTRS1978

Measurements of constituents of interest in the photochemistry of the ozone layer using infrared techniques

Infrared solar spectra and infrared atmospheric emission spectra were obtained from the ground, from aircraft and from balloons. The initial detection of most stratospheric molecules was achieved by the solar spectral technique because better resolution helps remove interference from other molecules. Because the sun is an intense source of radiation, the resolution which can be obtained with good signal-to-noise, is greater than with atmospheric emission spectroscopy. Data are generally taken using a method that enhances the number of molecules in the optical path i.e. at large solar zenith angles for solar spectra and at low elevation angles for atmospheric emission spectra. The search for molecules which are predicted to be present but which, the detection of a molecule known to be present from other measurement techniques but observed for the first time in infrared solar spectra, and some further data on the variability of HNO3 are discussed.

Murcray, D. G.↗

NASA NTRS1979

Study of periodic motions of a satellite with a magnetic damper

The motion of a satellite with a magnetic damper in the plane of a circular polar orbit is studied. The asymptotics of periodic solutions are constructed for a satellite close to axisymmetric and the radius of convergence is evaluated for the power series obtained. In a broad range of values of parameters, a periodic solution is obtained by numerical integration of equations of motion of the satellite. The asymptotics of a bifurcated curve obtained (the curve on which origin of a pair of periodic solutions occurs) in the space of the parameters agrees well with the results of numerical computation with all physical values of these parameters. A breakdown is made of the space of the initial data of phase variables in the field of effect of different types of periodic motion.

Sadov, Y. A.↗

NASA NTRS1980

Overview on the study of the solar cycle from space

Recent insights into the workings of the solar system are reviewed as factors to be considered when formulating key questions to be answered during a large scale program to study the solar cycle. The main objectives of the Solar Cycle and Dynamics Mission are to determine the causes (physical origins and mechanisms) of the solar cycle and the effects of these mechanisms on the heliosphere, the vast region that includes the corona, interplanetary medium, and the terrestrial environment. The mission should be able to obtain synoptic data on solar variability associated with the cycle, and over at least a fraction of a single 11-year cycle.

Noyes, R. W.↗

NASA NTRS1982

A new interstellar component in the spectrum of HD 72127A

New high dispersion observations are reported of the very strong, broad interstellar K line of Ca II in the spectrum of HD 72127A, a star located near a filament of the Vela supernova remnant. When compared with similar observations made in 1977, the new data reveal temporal variability of the interstellar absorption, as shown both by the presence of a new, sixth line component and by a 25% increase in the total equivalent width of the K line. All five Ca II components which were seen in both years show very large column-density ratios N(Ca II) /N(Na I) at least equal to 9, probably arising from anomalously large interstellar gas-phase abundances of Ca caused by disruption of interstellar grains. Marked differences in the structure of the K line between the two early-type components of this binary star, which are separated by only 3000 AU, are confirmed.

Hobbs, L. M.↗

NASA NTRS1984

Estimating the Lifetimes of Nickel/Cadmium Cells

Equation based on model of flaw growth. Model assumes cell fails by growth of preexisting flaws. Flaws described by three important quantities: total number of flaws, distribution of flaw sizes and rate of flaw growth. When flaw reaches critical size failure occurs. Flaw concept, in addition to providing ready explanation for reduced lifetime, predicts two important charateristics: statistical variability of lifetime data and dependence of lifetime on volume of sample.

Fedors, R. F.↗

NASA NTRS1984

LANDSAT-4 horizon scanner performance evaluation

Representative data spans covering a little more than a year since the LANDSAT-4 launch were analyzed to evaluate the flight performance of the satellite's horizon scanner. High frequency noise was filtered out by 128-point averaging. The effects of Earth oblateness and spacecraft altitude variations are modeled, and residual systematic errors are analyzed. A model for the predicted radiance effects is compared with the flight data and deficiencies in the radiance effects modeling are noted. Correction coefficients are provided for a finite Fourier series representation of the systematic errors in the data. Analysis of the seasonal dependence of the coefficients indicates the effects of some early mission problems with the reference attitudes which were computed by the onboard computer using star trackers and gyro data. The effects of sun and moon interference, unexplained anomalies in the data, and sensor noise characteristics and their power spectrum are described. The variability of full orbit data averages is shown. Plots of the sensor data for all the available data spans are included.

Bilanow, S.↗

NASA NTRS1985

Influence of meteorological conditions on aerosol vertical distribution and composition off the northeast American coastline

The size distribution and composition of lower tropospheric aerosols were measured off the northeast American coastline under clear air and disturbed meteorological conditions. Under the clear air conditions observed on 5 August 1982, with air flow from west to east, sulfate-rich stratified layers are the dominant feature of aerosol distribution in the lowest 3000 m of the troposphere. The encroachment of a warm frontal system over the study area on 9 August 1982 resulted in dramatic changes in aerosol distribution and composition prior to any precipitation, probably due to increased vertical mixing and dilution of pollutant aerosols. Chloride becomes the dominant water soluble anion in the lower 3000 m, primarily due to a several fold decrease in sulfate. Although these results are limited to only two sets of measurements, the data indicate the variability which can occur in the tropospheric vertical aerosol distributions at remote locations. A knowledge of the structure and stability of these stratified layers is of particular importance to studies of the ocean-troposphere chemistry problem.

Sebacher, D. I.↗

NASA NTRS1985

A Bayesian approach to nonlinear inversion

Powerful methods are now available for solving linear parametric inverse problems. However, many inverse problems which arise in geohysics are nonlinear. Fortunately, it is possible to treat most of these with the air of linear perturbation theory and liner inversion. But a convenient method is needed for assessing the importance of nonlinearity in these quasi-linear problems. The present paper provides such a method. Matsu'ura and Jackson (1984) have presented a simple algorithm for evaluating the asymptotic covariance matrix fo estimation errors. In the present investigation, aspects of linear inversion are discussed, taking into account linear parametric inverse problems, nonuniqueness, prior information, confidence limits, conditional and marginal statistics, the relative importance of the prior and observational data, and standardized variables. Attention is also given to nonlinear inversion, and the application of the considered approaches to a number of examples.

Jackson, D. D.↗

NASA NTRS1985

Extraction of information from major element chemical analyses of lunar basalts

Major element chemical analyses often form the framework within which similarities and differences of analyzed specimens are noted and used to propose or devise models. When percentages are formed the ratios of pairs of components are preserved whereas many familiar statistical and geometrical descriptors are likely to exhibit major changes. This ratio preserving aspect forms the basis for a proposed framework. An analysis of compositional variability within the data set of 42 major element analyses of lunar reference samples was selected to investigate this proposal.

Butler, J. C.↗

NASA NTRS1986

The average magnetic field draping and consistent plasma properties of the Venus magnetotail

The detailed average draping pattern of the magnetic field in the deep Venus magnetotail is examined. The variability of the data ordered by spatial location is studied, and the groundwork is laid for developing a coordinate system which measured locations with respect to the tail structures. The reconstruction of the tail in the presence of flapping using a new technique is shown, and the average variations in the field components are examined, including the average field vectors, cross-tail current density distribution, and J x B forces as functions of location across the tail. The average downtail velocity is derived as a function of distance, and a simple model based on the field variations is defined from which the average plasma acceleration is obtained as a function of distance, density, and temperature.

Mccomas, D. J.↗