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The 22-year or double sunspot cycle as a cause for longitudinal displacements of atmospheric semi-permanent centers of action is studied. A difference in frequency of occurence of Icelandic lows between the two halves of the double sunspot cycle during winter seasons is found.
X-ray bursts are identified from the UCSD OSO-7 X-ray experiment data. X-ray spectroheliograms of OSO-5, H alpha activity at the limb, and the emergence and disappearance of sunspot groups at the limb were studied and 17 active centers were found as likely seats of the X-ray bursts beyond the limb. The analysis of 37 X-ray bursts and their physical parameters is presented. Results show that (1) the distributions of maximum temperature, maximum emission measure, and characteristic cooling time of the over-the-limb events do not significantly differ from those of disk events; (2) that radiation is the dominant cooling mechanism for the hot flare plasma; and (3) that the scale height for X-ray emission in the 5-10 keV range is large. Observations show that the fraction of soft X-ray bursts which have a nonthermal component is the same on and off of the disk. Hard X-ray emission over extended regions is indicated.
An economic and systems analysis of a data center was conducted. Current facilities for data storage of documentation are shown to be inadequate and outmoded for efficient data handling. Redesign of documents, condensation of the keypunching operation, upgrading of hardware, and retraining of personnel are the solutions proposed to improve the present data system.
Motivated by the heavy reliance upon the analytic orbit theory in orbit determination operations at the Goddard Space Flight Center (GSFC), a comparison study is performed for three classical analytical theories of artificial satellite motion about an oblate earth. The three analytical theories are: (1) Brouwer, (2) a modified Brouwer, i.e., Brouwer-Lyddane and Cohen, and (3) Vinti. Comparison results for each theory are produced for a number of representative satellites of current or past interest which proved amenable to analytic theory application. The uniformity of these results has significant implications for current and future mission operations and planning activities. Subsidiary topics arising from the results of this study which relate to the optimum usage of the individual theories are also discussed
Reflected light microscopy provides information on first-order shock transitions in iron and iron-nickel and permits discrimination of microstructures due to shock transitions from those imparted by thermal transitions. In addition, thin-foil electron microscopy is used to characterize magnetic transitions in fine-particle iron. First-order magnetic phase changes, such as that from the antiferromagnetic face centered cubic state to the ferromagnetic body centered cubic state, are studied with the aim of calibrating the shock and thermal mechanisms of magnetization in iron with a particle size range between 250 and 1200 A. The efficiency of remanence due to shock transition is also estimated.
Digital image centering algorithms were compared in a test involving microdensitometer raster scans of a refractor parallax series consisting of 22 stars on 26 plates. The highest accuracy in determining stellar image positions was provided by an algorithm which involved fitting of a symmetric Gaussian curve and a flat background to the image marginal density distributions. Algorithms involving transmission marginals instead of density marginals were found to be less accurate. The repeatability and computational efficiency of the digital image centering technique were also studied.
Using the Marshall Space Flight Center 25 kW Power Module (PM) reference design as a point of departure, the study defined evolutionary growth paths to 100 kW and above. A recommended development approach and initial configurations were described. Specific hardware changes from the reference design are recommended for the initial PM configuration to ensure evolutionary growth, improved replicability, and reduced cost. Certain functional changes are also recommended to enhance system capabilities.
The thirty-two meter drop tube at the Marshall Space Flight Center was used to study the effect of zero gravity containerless processing on the structure and properties of materials. The concept involves the suppression of heterogeneous nucleation of solid in liquid and, therefore, solidification accompanied by large degrees of undercooling. Under these conditions metastable phases can be formed or, at the very least, unique nonequilibrium microstructures (containing equilibrium phases) with unique properties can be produced. The drop tube solidification was applied to niobium base alloys with emphasis on the Nb-Ge binary system in an effort to produce metastable phases with high superconducting transition temperatures in bulk specimens. In the past, only lower Ge alloys (Nb-13 a/o, Nb-18 a/o, and Nb-22 a/o) could be undercooled. Higher Ge alloys (e.g., Nb-25 a/o Ge and Nb-27 a/o Ge) can now be undercooled on a routine basis.
A Goddard Space Flight Center program of science studies and technology development to provide the basis for future earth observation sensors employing multispectral linear array (MLA) technology is described. Establishment of MLA performance parameters and performance modeling make up the primary science activities. Critical technologies being developed include: short-wave infrared (SWIR) detector arrays, visible/and near infrared detector arrays, and passive cryogenic coolers. Supporting activities include: test and field instrument development, focal plane research and assessment laboratory, system simulation laboratory, calibration sources and techniques, optics, and thermal infrared arrays.
Narrow-band H-alpha filtergrams at + or - 1 A and + or - 2 A from the line center were used to study the asymmetry of flares. Of the 60 flares studied, 92% show red asymmetry while 5% show blue asymmetry. Typically, the filtergrams show a striking dominance of the red wing over the blue wing from onset until late in the decay phase. The difference in intensity of the flare emissions is further augmented by the extensiveness of the emission area in the brighter wing. New kernel-like emissions were often found many minutes after the flare maximum. Spatially, they are displaced from the previous kernels. The late emissions show the same asymmetry as that of the earlier part of the flare.
The NASA Johnson Space Center made an observational study of the radar-backscattering properties of corn and soybeans in commercial fields in a test site in Webster County, IA. Aircraft-based radar scatterometers measured the backscattering coefficient of the crops at three frequencies, 1.6 GHz (L-band), 4.75 GHz (C-band), and 13.3 GHz (Ku-band), at 10 sensor look-angles (5 to 50 degrees from the nadir in steps of 5 degrees), and with several polarization combinations. Among other findings, it was determined that: (1) row direction differences among fields affected significantly the radar-backscattering coefficient of the fields when the radar system used like-polarization at look-angles from 5 to 25 degrees; (2) row-direction differences had no effect on radar backscattering when the system used either cross-polarization or look-angles greater than 25 degrees regardless of the polarization; (3) wet surface-soil moisture conditions resulted in significantly poorer spectral separability of the two crops as compared to dry-soil conditions; and (4) on the dry-soil date, the best channel for separating corn from soybeans was the C-band cross-polarized measurement at a look-angle of 50 degrees.
The Wawa greenstone belt is located in the District of Algoma and extends east-northeast from Lake Superior to the western part of the Sudbury District in Ontario, Canada. Recent mapping by Attoh has shown that an unconformity at the base of the Dore' Formation and equivalent sedimentary rocks marks a significant stratigraphic break which can be traced throughout the volcanic belt. This break has been used to subdivide the volcanic-sedimentary into pre- and post-Dore' sequences. The pre-Dore' sequence includes at least two cycles of mafic-to-felsic volcanism, each capped by an iron-formation unit. The post-Dore' sequence includes an older mafic-to-felsic unit, which directly overlies sedimentary rocks correlated with the Dore' Formation, and a younger felsic breccia unit interpreted to have formed as debris flows from a felsic volcanic center. In the present study, samples of both the pre-and post-Dore' volcanic sequences were analyzed for major and trace elements, incuding rare earths (REE). This preliminary study is part of an ongoing program to assess the petrogenesis of the volcanic rocks of the Wawa greenstone belt.
A 1/50-scale model of the 40- by 80-Foot Wind Tunnel at Ames Research Center was used to study various air-exchange configurations. System components were tested throughout a range of parameters, and approximate analytical relationships were derived to explain the observed characteristics. It is found that the efficiency of the air exchanger could be increased (1) by adding a shaped wall to smoothly turn the incoming air downstream, (2) by changing to a contoured door at the inlet to control the flow rate, and (3) by increasing the size of the exhaust opening. The static pressures inside the circuit then remain within the design limits at the higher tunnel speeds if the air-exchange rate is about 5% or more. Since the model is much smaller than the full-scale facility, it is not possible to completely duplicate the tunnel, and it will be necessary to measure such characteristics as flow rate and tunnel pressures during implementation of the remodeled facility. The aerodynamic loads estimated for the inlet door and for nearby walls are also presented.
Graphite/epoxy filament-wound cases (FWC) for the solid rocket motors of the space shuttle are being made by NASA. The FWC cases are wound with AS4W graphite fiber impregnated with an epoxy resin and are about 1.4 inches or more thick. Graphite-epoxy composite laminates, unlike metals, can be damaged easily by low velocity impacts of objects like dropped tools. The residual tension strength of the FWC laminate, after impact, is being studied at Langley Research Center. The conditions that give minimum visual evidence of damage are being emphasized. A fracture mechanics analysis was developed to predict the residual strength, after impact, using radiographs to measure the size of the damage and an equivalent surface crack to represent the damage.
A long standing constraint on the study of micrometeorites has centered on difficulties in preparing them for analysis. This is due largely to their small dimensions and consequent practical limitations on sample manipulation. Chondritic micrometeorites provide a good example; although much has been learned about their chemistry and mineralogy almost nothing was known about such basic properties as texture and petrographic associations. The only way to assess such properties is to examine microstructure indigenous to the particles. Unfortunately, almost all micrometeorites, out of necessity, have been crushed and dispersed onto appropriate substances prior to analysis, and most information about texture and petrography was lost. Recently, thin-sections of individual extraterrestrial particles have been prepared using an ultramicrotome equipped with a diamond knife. This procedure has been applied to stratospheric micrometeorites and Solar Max impact debris. In both cases the sections have enabled observation of a variety of internal particle features, including textures, porosity, and petrographic associations. The sectioning procedure is described and analysis results for chondritic micrometeoroids and select particles from Solar Max are presented.
A large, comprehensive program is being conducted at Virginia Tech to study the effect of laminate thickness on the fracture strength of notched laminated composites. Part of this program has been the study of the chracteristics and development of subcritical crack-tip damage prior to failure. The study has concentrated on the center-cracked tension specimen geometry. Subcritical crack-tip damage has been studied using enhanced X-ray radiography and the laminate deply technique. This paper examines he role that delamination plays in affecting the fracture of (0/+ or - 45/90)ns and (0/+ or - 45)ns laminates at various values of n. The study has found that delaminations do occur in thin laminates (n = 1) and affect the strength of the laminate. However, in thick laminates such as (0/+ or 45)90ns, and (0/+ or - 45)20s, there is sufficient constraint to prevent delaminations from occurring in the interior region of he specimen. The final fracture surface is uniform in the interior and self-similar (collinear with the original starter notch), with 'shear-lip' type damage in the form of delaminations and matrix cracking in the first several plies at the surface. These differences in the type of fracture of the thin and thick laminates greatly affect the fracture strength.
Investigations in FY-85 were centered on three case study days in 1982. Two of these, March 6 and April 24, were Atmospheric Variability Experiment/Verical Atmospheric Sounder (AVE/VAS) days for which high spatial and temporal resolution RAOB and Vertical Atmospheric Sounder (VAS) data sets were available. The third investigation day, April 26, was a day of interesting severe weather. In the last part of FY-84 and early FY-85 we were able to demonstrate most importantly the complimentary nature of satellite soundings and winds in a forecast/analysis system. In our variational analysis scheme, cloud drift and water vapor winds enter into the height field as gradient information. The cloud drift winds especially, have the character of supplying information in cloudy areas where satellite soundings are not possible. In the April 26 experiments, analyses and forecasts using the combination satellite winds and soundings were superior to those using only soundings. Good consistency was shown between independent satellite forecasts from different initialization times run to the same verification time. A significant accomplishment in FY-85 was expanding experiments on April 26 to include quasi-continuous initialization inserting satellite soundings and winds from several different times into an analysis/forecast. Contrary to the first set of experiments on April 26, here forecast initialization fields were not independent, but contained satellite information from two data times.
A preliminary uncertainty analysis has been performed for the High Area Ratio Rocket Nozzle test program which took place at the altitude test capsule of the Rocket Engine Test Facility at the NASA Lewis Research Center. Results from the study establish the uncertainty of measured and calculated parameters required for the calculation of rocket engine specific impulse. A generalized description of the uncertainty methodology used is provided. Specific equations and a detailed description of the analysis are presented. Verification of the uncertainty analysis model was performed by comparison with results from the experimental program's data reduction code. Final results include an uncertainty for specific impulse of 1.30 percent. The largest contributors to this uncertainty were calibration errors from the test capsule pressure and thrust measurement devices.