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NASA NTRS1991

Proceedings of the NSSDC Conference on Mass Storage Systems and Technologies for Space and Earth Science Applications

The proceedings of the National Space Science Data Center Conference on Mass Storage Systems and Technologies for Space and Earth Science Applications held July 23 through 25, 1991 at the NASA/Goddard Space Flight Center are presented. The program includes a keynote address, invited technical papers, and selected technical presentations to provide a broad forum for the discussion of a number of important issues in the field of mass storage systems. Topics include magnetic disk and tape technologies, optical disk and tape, software storage and file management systems, and experiences with the use of a large, distributed storage system. The technical presentations describe integrated mass storage systems that are expected to be available commercially. Also included is a series of presentations from Federal Government organizations and research institutions covering their mass storage requirements for the 1990's.

Blackwell, Kim↗
NASA NTRS1992

NSSDC Conference on Mass Storage Systems and Technologies for Space and Earth Science Applications, volume 2

This report contains copies of nearly all of the technical papers and viewgraphs presented at the NSSDC Conference on Mass Storage Systems and Technologies for Space and Earth Science Application. This conference served as a broad forum for the discussion of a number of important issues in the field of mass storage systems. Topics include the following: magnetic disk and tape technologies; optical disk and tape; software storage and file management systems; and experiences with the use of a large, distributed storage system. The technical presentations describe, among other things, integrated mass storage systems that are expected to be available commercially. Also included is a series of presentations from Federal Government organizations and research institutions covering their mass storage requirements for the 1990's.

Kobler, Ben↗
NASA NTRS1992

A Remote Laser Mass Spectrometer for Lunar Resource Assessment

The use of lasers as a source of excitation for surface mass spectroscopy has been investigated for some time. Since the laser can be focused to a small spot with intensity, it can vaporize and accelerate atoms of material. Using this phenomenon with a time-of-flight mass spectrometer allows a surface elemental mass analysis of a small region with each laser pulse. While the technique has been well developed for Earth applications, space applications are less developed. NASA Langley recently began a research program to investigate the use of a laser to create ions from the lunar surface and to analyze the ions at an orbiting spacecraft. A multijoule, Q-switched Nd:YAG laser would be focused to a small spot on the lunar surface, creating a dense plasma. This plasma would eject high-energy ions, as well as neutrals, electrons, and photons. An experiment is being set up to determine the characteristics of such a laser mass spectrometer at long flight distances. This experiment will determine the character of a future flight instrument for lunar resource assessment.

Deyoung, R. J.↗
NASA NTRS1992

The mass of (1) Ceres from perturbations on (348) May

The most promising ground-based technique for determining the mass of a minor planet is the observation of the perturbations it induces in the motion of another minor planet. This method requires careful observation of both minor planets over extended periods of time. The mass of (1) Ceres has been determined from the perturbations on (348) May, which made three close approaches to Ceres at intervals of 46 years between 1891 and 1984. The motion of May is clearly influenced by Ceres, and by using different test masses for Ceres, a search was made to determine the mass of Ceres that minimizes the residuals in the observations of May.

Williams, Gareth V.↗
NASA NTRS1992

Lumped mass modelling for the dynamic analysis of aircraft structures

Aircraft structures may be modelled by lumping the masses at particular strategic points and the flexibility or stiffness of the structure is obtained with reference to these points. Equivalent moments of inertia for the section at these positions are determined. The lumped masses are calculated based on the assumption that each point will represent the mass spread on one half of the space on each side. Then these parameters are used in the differential equation of motion and the eigen characteristics are determined. A comparison is made with results obtained by other established methods. The lumped mass approach in the dynamic analysis of complicated structures provides an easier means of predicting the dynamic characteristics of these structures. It involves less computer time and avoids computational errors that are inherent in the numerical solution of complicated systems.

Abu-Saba, Elias G.↗
NASA NTRS1993

The mass balance of the ice plain of Ice Stream B and Crary Ice Rise

The region in the mouth of Ice Stream B (the ice plain) and that in the vicinity of Crary Ice Rise are experiencing large and rapid changes. Based on velocity, ice thickness, and accumulation rate data, the patterns of net mass balance in these regions were calculated. Net mass balance, or the rate of ice thickness change, was calculated as the residual of all mass fluxes into and out of subregions (or boxes). Net mass balance provides a measure of the state of health of the ice sheet and clues to the current dynamics.

Bindschadler, Robert↗
NASA NTRS1992

Properties of mass-loading shocks. II - Magnetohydrodynamics

The one-dimensional magnetohydrodynamics of mass-loading shocks is examined. These shocks, which are distinct from MHD shocks of classical nonreacting fluid dynamics and of combustion theory and which are characterized by the addition of mass within the shock transition, are to be found at comets and, depending upon circumstances, at nonmagnetized and weakly magnetized planets such as Venus and Mars. A completely general mass-loading form of the Hugoniot equation is derived, and some of the most important differences between mass-loading and nonreacting classical MHD shocks are identified. Two new types of MHD shocks are described which have no classical MHD analogues.

Zank, G. P.↗
NASA NTRS1993

Mass density and pressure changes across the dayside magnetopause

Plasma composition measurements at about 2-min time resolution from 27 magnetopause crossings are used to determine if mass density rho, modified by the anisotropic pressure term (1-alpha), is constant across the magnetopause. Pressure and mass density in the magnetosheath and low-latitude boundary layer were found to be dominated by H(+) except on one occasion when O(+) was the dominant contributor to the total mass density in the low-latitude boundary layer. Using these measurements, it is found that rho(1-alpha) is not constant for almost all magnetopause crossings even when there is independent evidence for magnetic reconnection and an open magnetopause. These results indicate that the reason why rho(1-alpha) is not constant across the magnetopause is that the H(+) density decrease from the magnetosheath to the low-latitude boundary layer is not compensated for by either a change in the pressure anisotropy or a change in the total mass density and suggest that the magnetopause can never be described as a time-stationary 1D rotational discontinuity.

Fuselier, S. A.↗
NASA NTRS1993

The structure of mass-loading shocks

A new two-fluid model which describes mass loading in the solar wind (e.g., the interaction of the solar wind with a cometary coma or the local interstellar medium) is presented. The self-consistent back-reaction of the mass-loaded ions is included through their effective scattering in low-frequency MHD turbulence and the invocation of a diffusive approximation. Such an approximation has the advantage of introducing self-consistent dissipation coefficients into the governing equations, thereby facilitating the investigation of the internal structure of shocks in mass-loading environments. To illustrate the utility of the new model, we consider the structure of cometary shocks in the hypersonic one-dimensional limit, finding that the incoming solar wind is slowed by both mass loading and the development of a large cometary ion pressure gradient. The shock is broadened and smoothed by the cometary ions with a thickness of the order of the cometary ion diffusion scale.

Zank, G. P.↗
NASA NTRS1991

Development of a miniaturized gas chromatograph-mass spectrometer with a microbore capillary column and an array detector

A review is presented of the demonstration of a miniaturized focal plane mass spectrograph using a microbore capillary column with an array detector to measure multiple mass spectra from narrow and closely eluted gas chromatograph peaks. It is shown that the system possesses high sensitivity and a high speed of spectral mass measurements. The combination of the capillary column with the miniaturized mass spectrograph is uniquely suited for the development of a field-portable, high-performance system.

Sinha, Mahadeva P.↗
NASA NTRS1993

On the evaluation of air mass factors for atmospheric near-ultraviolet and visible absorption spectroscopy

The interpretation of UV-visible twilight absorption measurements of atmospheric chemical constituents is dependent on how well the optical path, or air mass factor, of light collected by the spectrometer is understood. A simple single scattering model and a Monte Carlo radiative transfer scheme have been developed to study the effects of multiple scattering, aerosol scattering, surface albedo and refraction on air mass factors for scattered light observations. At fairly short visible wavelengths (less than about 450 nm), stratospheric air mass factors are found to be relatively insensitive to multiple scattering, surface albedo and refraction, as well as aerosol scattering by background aerosols. Longer wavelengths display greater sensitivity to refraction and aerosol scattering. Tropospheric air mass factors are found to be highly dependent on aerosol scattering, surface albedo and, at long visible wavelengths (about 650 nm), refraction. Absorption measurements of NO2 and O4 are shown to support these conclusions.

Perliski, Lori M.↗
NASA NTRS1993

IRAS galaxies versus POTENT mass - Density fields, biasing, and Omega

A comparison of the galaxy density field extracted from a complete redshift survey of IRAS galaxies brighter than 1.936 Jy with the mass-density field reconstructed by the POTENT procedure from the observed peculiar velocities of 493 objects is presented. A strong correlation is found between the galaxy and mass-density fields; both feature the Great Attractor, part of the Perseus-Pisces supercluster, and the large void between them. Monte Carlo noise simulations show that the data are consistent with the hypotheses that the smoothed fluctuations of galaxy and mass densities at each point are proportional to each other with the 'biasing' factor of IRAS galaxies, b(I), and that the peculiar velocity field is related to the mass-density field as expected according to the gravitational instability theory. Under these hypotheses, the two density fields can be related by specifying b(I) and the cosmological density parameter, Omega.

Dekel, Avishai↗
NASA NTRS1991

Jet ejecta mass upon oblique impact

Theoretical models in the jetting regime for symmetric and asymmetric impact of thin plates predict the mass and velocity of jetted material upon oblique impact. However, experimental constraints on the amount of material which form jets upon oblique impact are not known. A series of preliminary experiments were conducted in which tungsten (W) flyer plates at speeds of 1.5 to 2.0 km/s were obliquely impacted into carbon targets at 30 deg in the regime of jetting, yielding radiation temperatures in the about 3200 K range. Both framing-camera and flash X-ray imaging were conducted. Broad cm-sized craters induced by jet ejecta on 2024 Al witness plates were used to infer jet mass. We infer, from measured witness plate crater volumes, that jet masses in the range of 0.01 to 0.06 g are produced by a 32 mm diameter, 6 mm thick W impactor. This is about one to two orders of magnitude less than those calculated from present theoretical models. In contrast, in refractory material experiments, the mass of gabbro ejecta trapped in styrofoam is 0.52 g, which is similar to that calculated.

Yang, W.↗
NASA NTRS1937

Considerations affecting the additional weight required in mass balance of ailerons

This paper is essentially a consideration of mass balance of ailerons from a preliminary design standpoint, in which the extra weight of the mass counterbalance is the most important phase of the problem. Equations are developed for the required balance weight for a simple aileron and this weight is correlated with the mass-balance coefficient. It is concluded the location of the c.g. of the basic aileron is of paramount importance and that complete mass balance imposes no great weight penalty if the aileron is designed to have its c.g. inherently near to the hinge axis.

Diehl, W S↗
NASA NTRS1993

Iron and nickel isotopic mass fractionation in deep-sea spherules

Magnetite-wuestite spherules collected from deep-sea sediments are thought to have originally been Fe-Ni metal particles at the top of the atmosphere that were oxidized and melted during entry into the earth's atmosphere. Some likely sources for the metal particles are Fe-Ni interplanetary dust particles (IDP's) and metal or sulfide from stony IDP's that separated after melting. Davis et al. reported that four of these spherules are enriched in the heavy isotopes of iron, with enrichments of 8-23%/amu. We have developed a technique for analysis of both iron and nickel isotopes on the same ion microprobe spot and have applied this technique to a number of deep-sea spherules in order to better understand the processes leading to isotopic mass fractionation. Eight spherules show iron and nickel isotopic mass fractionation, with iron and nickel enriched in the heavy isotopes by 10-19%/amu and 4-32%/amu, respectively. If the mass fractionations are due to Rayleigh fractionation during evaporation, these spherules lost 76-94% of their original mass. We have analyzed the four magnetite-wuestite spherules for which iron isotopic data were reported by Davis et al. as well as four new spherules.

Davis, Andrew M.↗
NASA NTRS1993

Normalized vertical ice mass flux profiles from vertically pointing 8-mm-wavelength Doppler radar

During the FIRE 2 (First International Satellite Cloud Climatology Project Regional Experiment) project, NOAA's Wave Propagation Laboratory (WPL) operated its 8-mm wavelength Doppler radar extensively in the vertically pointing mode. This allowed for the calculation of a number of important cirrus cloud parameters, including cloud boundary statistics, cloud particle characteristic sizes and concentrations, and ice mass content (imc). The flux of imc, or, alternatively, ice mass flux (imf), is also an important parameter of a cirrus cloud system. Ice mass flux is important in the vertical redistribution of water substance and thus, in part, determines the cloud evolution. It is important for the development of cloud parameterizations to be able to define the essential physical characteristics of large populations of clouds in the simplest possible way. One method would be to normalize profiles of observed cloud properties, such as those mentioned above, in ways similar to those used in the convective boundary layer. The height then scales from 0.0 at cloud base to 1.0 at cloud top, and the measured cloud parameter scales by its maximum value so that all normalized profiles have 1.0 as their maximum value. The goal is that there will be a 'universal' shape to profiles of the normalized data. This idea was applied to estimates of imf calculated from data obtained by the WPL cloud radar during FIRE II. Other quantities such as median particle diameter, concentration, and ice mass content can also be estimated with this radar, and we expect to also examine normalized profiles of these quantities in time for the 1993 FIRE II meeting.

Orr, Brad W.↗
NASA NTRS1993

A representation for the turbulent mass flux contribution to Reynolds-stress and two-equation closures for compressible turbulence

The turbulent mass flux, or equivalently the fluctuating Favre velocity mean, appears in the first and second moment equations of compressible kappa-epsilon and Reynolds stress closures. Mathematically it is the difference between the unweighted and density-weighted averages of the velocity field and is therefore a measure of the effects of compressibility through variations in density. It appears to be fundamental to an inhomogeneous compressible turbulence, in which it characterizes the effects of the mean density gradients, in the same way the anisotropy tensor characterizes the effects of the mean velocity gradients. An evolution equation for the turbulent mass flux is derived. A truncation of this equation produces an algebraic expression for the mass flux. The mass flux is found to be proportional to the mean density gradients with a tensor eddy-viscosity that depends on both the mean deformation and the Reynolds stresses. The model is tested in a wall bounded DNS at Mach 4.5 with notable results.

Ristorcelli, J. R.↗
NASA NTRS1994

Mass analysis addition to the Differential Ion Flux Probe (DIFP) study

The objective of this study is to develop a technique to measure the characteristics of space plasmas under highly disturbed conditions; e.g., non-Maxwellian plasmas with strong drifting populations and plasmas contaminated by spacecraft outgassing. The approach, conducted in conjunction with current MSFC activities, is to extend the capabilities of the Differential Ion Flux Probe (DIFP) to include a high throughput mass measurement that does not require either high voltage or contamination sensitive devices such as channeltron electron multipliers or microchannel plates. This will significantly reduce the complexity and expense of instrument fabrication, testing, and integration of flight hardware compared to classical mass analyzers. The feasibility of the enhanced DIFP has been verified by using breadboard test models in a controlled plasma environment. The ability to manipulate particles through the instrument regardless of incident angle, energy, or ionic component has been amply demonstrated. The energy analysis mode is differential and leads directly to a time-of-flight mass measurement. With the new design, the DIFP will separate multiple ion streams and analyze each stream independently for ion flux intensity, velocity (including direction of motion), mass, and temperature (or energy distribution). In particular, such an instrument will be invaluable on follow-on electrodynamic TSS missions and, possibly, for environmental monitoring on the space station.

Wright, K. H., Jr.↗