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Active Magnetic Control System For Gravity Gradient Stabilized Spacecraft, Francois Martel, Parimal Pal, Mark Psiaki

Small Satellite Conference

Active magnetic control is studied as a means to improve the capabilities and performance of gravity gradient stabilized spacecraft. Active magnetic control eliminates the need for a passive damper and can reduce significantly the costs and complexity of other functional parts of the spacecraft. The system under study includes three magnetic torquers, one three-axis magnetometer, and a control processor. It does not require any moving parts, and provides for rapid libration damping, tighter stabilization and active control of the yaw angle. Control algorithms are defined. Results of the analysis of the control laws and computer simulations, including high-order models of …

A Feasibility Study For A Remotely Controlled, Low-Power- Consumption Scanning Electron Microscope Suitable For Space Applications, John Chidester, Lynn Chidester

Small Satellite Conference

Experiments and instruments for operation in and on small satellites are constrained by the volume, weight, power, and ruggedness requirements of the satellite design and structure. It is anticipated that increasing numbers of "laboratory" style experiments will be performed in space. An application of current interest is the in-space observation of material surfaces exposed to the space environment. One such instrument for possible small satellite flight operational use, is a scanning electron microscope (SEM). The design factors and parameters of such an SEM, as well as the trade-offs and instrument limitations, will be discussed. The electronic control and image relay …

Observations Of Single-Event Memory Upsets On The Uosat-2 Satellite, Jeff Ward

Small Satellite Conference

This paper describes observations of single-event memory upsets in the UoSAT-2 satellite Digital Communications Experiment. Two years of SEU observations for Harris 6564 memories are included, presented both as error rate statistics and as a map of satellite orbital location at the time of error occurrence. The results presented here are the preliminary observations in a long-term single-event upset study funded by ESA-ESTEC.

Space - Radiation Qualification Of A Microprocessor Implemented For The Intel 80186, R.H. Maurer, J.D. Kinnison, B.M. Romenesko, B.G. Carkhuff, R.B. King

Small Satellite Conference

The Intel 80186 sixteen-bit microprocessor is an example of a high performance device (8 MHz) needed to carry out advanced experimentation on Low Earth Orbit missions. However, this key complex microprocessor is not space-qualified. We will discuss the procedures necessary to qualify a microprocessor for the natural space radiation environment. We also present the results from our single event upset tests on the 80186. The upset cross-section exhibited a threshold of 0.4 MeV-cm²/mg, a knee at 7 MeV-cm²/mg and an asymptotic value of 5x10-4cm². The upset cross-section did not depend on frequency in the 4-8 MHz range and increased by …

Designing A Small Satellite - Starsat, Thomas Lash

Small Satellite Conference

STARSAT, the Standardized Teaching and Research Satellite, is a small, low-cost satellite being designed and but It at the USAF Academy. The basic function of STARSAT is to expand upon NASA's Get-Away-Special concept by al lowing similar type payloads to be flown in low earth orbit for extended periods of time. As a standardized spacecraft bus, STARSAT will be able to support a variety of such research payloads. While research is a major goal, STARSAT is also an outstanding tool to aid in teaching undergraduate engineering students. This paper describes the technical specifications for the spacecraft, ground support, launch support …

The Italian Approach To Small Satellites For Low Cost Access To Space Developments, G. Rondinelli, G. Barresi, A. Cramarossa, F. Graziani

Small Satellite Conference

Several technological institutions and scientific center are presently forbidden to access space exploration, because of the high costs involved with satellite development and launch. ITALSPAZIO has performed several studies directed toward the minimization of such costs. Possible design approaches are: use of a small bus capable to fly at marginal cost on expendable launch vehicles by paying delta-costs when passing from one launcher class to the upper next of the same launcher, (an example is constituted by the ARIANE IV when passing from AIRANE 40 to ARIANE 42s); use of left-over launcher capacities; use of subsystems and equipment’s developed for …

The Avatar Small Spacecraft System, Joseph Leblanc

Small Satellite Conference

American Microsat president Joseph A. LeBlanc will present the AVATAR Small Spacecraft System. The AVATAR Small Spacecraft System consists of the AVATAR satellite modules and the ground control and data collection facility. The AVATAR spacecraft is comprised of modules containing specific mission subsystems that are designed to work together or independently to satisfy mission requirements. Four modules provide payload space, control, propulsion and three axis stabilization. The different modules (described below) and the customer launch options will be discussed separately during the presentation. Common Services Module: The Common Services Module houses the spacecraft computer, the TT&C communications equipment, the attitude …

Deep Space Missions For Small Satellites, Paula Butler, Alan Stein

Small Satellite Conference

Small satellites, with masses well under 100 kg, can perform useful deep space science missions for costs similar to those of low earth orbit and geosynchronous smallsats. Space Explorations has identified several interesting missions for smallsats, with the objective of developing "turnkey" space-science packages which would have a cost to the customer of $10,000,000 and be operable by one or a few people. We have analyzed one mission, a Lunar Polar Photographic Orbiter, in great detail over the last year. We conclude that it is commercially and scientifically feasible to produce a small lunar satellite which is capable of doing …

An Approach To The Design Of A Lightweight Lunar Spacecraft, G.E. Sevaston, D.H. Lehman, K.T. Nock

Small Satellite Conference

The Quicksat study, undertaken at the Jet Propulsion Laboratory (JPL), had as its goal the development of low mass, low cost spacecraft that can be implemented within a relatively short time span. As part of this effort, JPL studied a lunar mission referred to as Lunar Prospector (LP). The LP spacecraft carries a spare Apollo gamma ray spectrometer (GRS) in a 100 km polar orbit about the moon in order to obtain a global map of surface composition. The primary mission objective is to search for water in the form of ice trapped within polar craters; this is viewed as …

The Uosat-C,D & E Technology Demonstration Satellites, N.P. Bean, J.M. Radbone, M.N. Sweeting, J.W. Ward

Small Satellite Conference

The University of Surrey (UK) planned a small, inexpensive spacecraft (UoSAT-C) to be launched by NASA on a DELTA launch vehicle as a secondary payload into low-Earth orbit in 1989. This launch has been postponed, but the University has obtained two launch slots on ARIANE. Two spacecraft, UoSATs D & E are currently under construction at The UoSAT Spacecraft Engineering Research Unit at Surrey and they involve collaboration with international experimenters. The spacecraft will carry the majority of the payloads from the postponed UoSAT-C mission. UoSAT-D & E will established by the spacecraft launched NASA, develop further the objectives preceding …

X-Ray Analysis Of Biological Fluids: An Update, G. A. Quamme

Scanning Microscopy

X-ray analysis has been used for some twenty years to quantify elements including Na, K, Cl, Ca, Mg and phosphorous in biological fluid samples. The method consists of accurate pipetting of 50-150 pl samples and appropriate drying to form crystalline deposits. Quantitation is obtained by comparison of x-ray intensities with comparable standard crystalline deposits. Electon microprobe analyses have contributed much to our understanding of renal transport function including physiological controls and pathological influences on the tubular handling of the major elements. New approaches to x-ray analysis of solid tissue will further our knowledge concerning transport properties in the kidney and …

Stopping Power For Low-Energy Electrons, R. M. Nieminen

Scanning Microscopy

Descriptions of inelastic processes for the slowing down of electrons in condensed matter are presented for the energy range between a few eV and a few keV. Attempts at quantitative theories of stopping are summarized, with an emphasis on obtaining useful cross section expressions for Monte Carlo simulations and analytic transport theories. Inelastic scattering with both electrons (conduction and core) and density fluctuations (phonons) are included. The main emphasis in the theories for the former is in the dielectric (self-energy) formulation for the conduction band and in using generalized oscillator strengths or semiclassical excitation functions for the core. Recent applications …

Contrast And Resolution Of Secondary Electron Images In A Scanning Transmission Electron Microscope, J. Liu, J. M. Cowley

Scanning Microscopy

Recent advances in the improvement of secondary electron image resolution to the subnanometer level demand further knowledge of the origin of secondary electron emission to interpret the experimental results. The generally accepted estimation of the non-localized range of the inelastic scattering of incident electrons and the subsequent generation of secondary electrons in a solid cannot explain the 0.7 nm resolution of secondary electron images obtained in a scanning transmission electron microscope operated at 100 kV. Resolution and contrast of secondary electron images are interrelated. High contrast as well as high resolution can be obtained at the same time. Contrast mechanisms …

Determination Of Fiber Content In Long Fiber Reinforced Composites By Scanning Electron Microscopy And Image Analysis, R. F. Antrim

Scanning Microscopy

Currently, there is a wide interest in further developing long fiber reinforced composites. Due to the dependence of a material's mechanical properties to its microstructure, further development of microanalytical techniques is needed to quantify the amount of fiber. In response, a standardless technique was developed to determine the volumetric fiber content and its variation in an oriented long fiber reinforced composite. The method utilizes scanning electron microscopy to acquire backscattered electron images of polished cross-sections. The images are then processed to determine the fiber area fraction which, in this particular case, is equal to the volume fraction. The results presented …

Scanning Electron Microscopy Studies Of Extended Defects In Semiconductors, C. A. Dimitriadis

Scanning Microscopy

Extended defects, such as dislocations and grain boundaries, play an important role in determining the performance of various semiconductor devices. This paper reviews applications of electron-beam-induced-current and cathodoluminescence scanning electron microscopy for the investigation of dislocations and grain boundaries in semiconductors. We developed a simple analytical method for the determination of the grain boundary recombination velocity and the minority carrier diffusion length, in contrast to a previous method which requires the use of a computer for the numerical calculation of an integral expression. We, also, studied theoretically the influence of an individual dislocation on the minority carrier lifetime. Investigation of …

Transport Models For Backscattering And Transmission Of Low Energy ( < 3 Kilovolts) Electrons From Solids, H. Lanteri, R. Bindi, P. Rostaing

Scanning Microscopy

This paper deals with the backscattering and the transmission of electrons with energy < 3 keV through thin self supporting films, or on bulk metals.

We present the main theoretical models used in such problems, and we analyse mainly the models based on the Boltzmann transport equation, similar to those developed in our laboratory.

For any model shown here, we try to give the precise domain in which they give reliable results as well as the limitations connected to the simplifying assumptions.

In the case of the most sophisticated model, we give original results for copper. The models are presented in a comparative form, and when it is possible we compare our …

Ultrastructural Characteristics Of The Fetal And Neonatal Rat Urinary Bladder, Samuel M. Cohen, Martin Cano, Takao Sakata, Sonny L. Johansson

Scanning Microscopy

The embryologic and neonatal development of the normal rat urinary bladder was investigated in Sprague-Dawley rats by light, transmission, and scanning electron microscopy from day 11 of gestation through 21 days of age. The epithelium at day 11 of gestation is composed of small, loosely-connected, rounded cells with occasional short microvilli on their surfaces. The large polygonal cells characteristic of the adult bladder begin to appear by day 15, but the microridges are not apparent until day 17. By day 20, the epithelium appears morphologically similar to the adult bladder. Several morphological features are observed at different times of gestation …

An Experimental Scanning Capacitance Microscope, H. P. Kleinknecht, J. R. Sandercock, H. Meier

Scanning Microscopy

A fine needle stylus mounted to a three-dimensional piezo system is scanned across the sample in x-and y-direction, while a constant spacing between tip and sample, i.e., constant tip-to-sample capacitance, is maintained in z-direction. This is accomplished by vibrating the tip in z-direction at 1 kHz by typically 0.1 microns and by detecting the capacitance modulation from the shifting of the resonance of a tuned 1 GHz line. The horizontal resolution achieved so far is limited by the tip radius at about 200 nm and the vertical resolution is about 5 nm. The theoretical limits for finer tips are 7 …

Detectors For Quantitative Electron Beam Voltage Measurements, A. R. Dinnis

Scanning Microscopy

Qualitative voltage contrast is produced without difficulty in any SEM. Complete separation of the voltage contrast from other sources of contrast is not a straightforward matter because of the nonlinear relations between the phenomena causing contrast and the video signal.

Quantitative measurements depend on the availability of electron energy analysers which can detect accurately the shift in secondary electron energies due to potentials appearing on integrated circuit tracks, without being affected by transverse fields due to potentials on other conductors or insulators. The principles underlying existing detectors are explained, their effectiveness assessed, and a new form of electron detector is …

Signal Of Backscattered Electrons From Multiple Marks In Dependence On Mark Profile, D. Kaczmarek, Z. Czyżewski

Scanning Microscopy

The backscattered electron signal can be detected using a solid state detector system. Because this signal is affected by the surface topography it is necessary to determine the optimal detection condition for a registration mark detection in the electron-beam lithography and for an automatic topographical surface reconstruction.

The BSE signal from surface marks has been measured using semiconductor detectors with a small collection angle. Calculations of the BSE signal have been carried out by means of a simplified model of electron backscattering. The signal shape depends on some parameters of the mark profile, such as length, height and inclination angle …

Contribution Of Densely Distributed Electron Beam Induced Current Contrasts In Annealed Cz Silicon To Bulk Recombination, M. Kittler, W. Seifert

Scanning Microscopy

The paper presents a detailed analysis of Electron Beam Induced Current (EBIC) diffusion-length and contrast data for samples containing defect accumulations. The formulae given allow one to estimate to which extent the average diffusion length is determined by recombination-active defects showing EBIC contrast.

This analysis may be used to identify essential sources of bulk recombination in annealed silicon. In the light of our results stacking faults are an essential source of bulk recombination in intrinsically gettered p-type Cz silicon.

The Influence Of Analyser Geometry Effects In Scanning Electron Microscope Voltage Contrast Measurements, Daniel S.H. Chan, Teck Seng Low, Wai Kin Chim, Jacob C. H. Phang

Scanning Microscopy

A computer simulation model used to study specimen dependent and analyser geometry dependent effects is described in this paper. With this model, the influence of the specimen dependent effect on quantitative voltage contrast measurements can be isolated from the analyser geometry dependent effect. Linearization error voltages in quantitative voltage contrast measurements arising from the individual influences of the specimen dependent and analyser geometry dependent effects are presented. The results show that the error component due to very narrow analysers dominate the total linearization error. The same situation arises when the voltage measurement point on the specimen is very near to …

An Electron Microscopic Study Of Hemopoietic Tissues In The Course Of Lewis Lung Carcinoma, Cheryl Hardy, Yuzhi Wang, Bettye Collier, Mehdi Tavassoli

Scanning Microscopy

Lewis lung carcinoma of C57Bl/6 mice causes a progressive anemia with reticulocytosis and splenomegaly, metastasizes to lungs, liver, and kidneys but does not invade hemopoietic tissues. The cause of this anemia is uncertain. We studied the structure of spleen and bone marrow in these tumor hosts by light and electron microscopy. Splenic congestion of the red pulp with numerous erythropoietic islands and marrow hyperplasia characterized the hemopoietic tissues of these mice, which, when coupled with other hematological parameters suggested a hemolytic condition. However, the erythropoietic response appeared to be in part ineffective as evidenced by phagocytosis of immature as well …

Secondary Ion Mass Spectrometry Studies Of Isotope Effect In Diffusion, U. Södervall, H. Odelius, A. R. E. Lodding

Scanning Microscopy

The mass effect of diffusion is of interest in connection with interactions between defects and impurities and with the mechanisms of atomic displacements in the condensed states. The delineation entails the precise measurement of the isotope ratio as function of tracer concentration, varying within several orders of magnitude along the diffusion profile. The measurement by SIMS (secondary ion mass spectrometry), using stable isotopes, has proved to possess advantages compared to familiar techniques with radiotracers. However, the aims require the utmost counting economy and optimal precision available in SIMS, including the control of the mass fractionation and of some features peculiar …

Utah Science Vol. 49 No. 2, Summer 1988

Utah Science

30 ENVIRONMENTAL REGULATION AND ECONOMIC AND COMMUNITY DEVELOPMENT J. C. Andersen, H. H. Fullerton, E. B. Godfrey, W. C. Lewis and D. L. Snyder An examination of the costs and benefits of environmental regulation.

38 CLOTHING TO REDUCE EXPOSURE TO PESTICIDES V. B. Keeble New types of protective clothing developed and tested at USU significantly reduced exposure to pesticides.

44 A SURVEY OF THE FINANCIAL CONDITION OF UTAH DAIRY FARMS IN 1985 D. Bailey. G. O. Jenson and N. Ackerman Some dairy farmers are in good financial condition, others aren't This article examines the reasons underlying this dichotomy.

49 MANAGING …

Basis Of The Structure And Development Of Mammalian Enamel As Seen By Scanning Electron Microscopy, A. Boyde, M. Fortelius, K. S. Lester, L. B. Martin

Scanning Microscopy

Mature enamel is the most mineralized of mammalian tissues, contains the least water and therefore does not present problems of shrinkage on preparation for SEM. However, the developing enamel is highly hydrated and presents severe problems in preparation.

The structure of enamel is determined by the activity of its individual formative cells and their group behaviour. The peculiar, unequal secretion of matrix at the distal pole of the ameloblast leads to the presence of characteristically shaped pits in the surface of the formative tissue. Crystals grow in a special relationship to this surface. Sharp changes in orientation of the surface …

Quantitative Analysis Of Particulate Burden In Lung Tissue, J. P. Mastin, L. E. Stettler, J. D. Shelburne

Scanning Microscopy

Numerous methods have been used in the preparation and analysis of the particulate matter deposited in human lungs. Preparation techniques include those for particle isolation and for in situ analysis. Analytical techniques include bulk and particle-by-particle analysis. In this paper, a general discussion of many of these methods is presented along with examples of how two specific techniques have been used. In one study, individual particles from the lungs of 75 randomly selected autopsy cases were analyzed using an automated scanning electron microscopy (SEM)/ energy dispersive X-ray microanalysis (EDX) system. An average of 613 million particles, of exogenous origin, per …

Defect Detection And Thickness Mapping Of Passivation Layers On Integrated Circuits Using Energy Dispersive X-Ray Analysis And Image Processing Techniques, Richard G. Sartore

Scanning Microscopy

The relative thickness of passivation layers has been mapped for integrated circuits by utilizing the penetration voltage method, in conjunction with energy dispersive x-ray analysis (EDXA) and a scanning electron microscope (SEM), to detect defects and map film thickness. The thickness mapping technique was evaluated for area coverage and correlated to size of defective areas. The purpose of this study was to determine optimal operational conditions for fast and accurate defect detection on an integrated circuit for failure analysis and non-destructive process evaluation. Image processing was required to enhance the acquired map and to obtain a calibrated image for relative …

Determination Of Nitrogen In Stainless Steel By Auger Electron Spectroscopy, H. Hantsche, H. J. Dudek

Scanning Microscopy

Application properties of steel can be improved considerably by alloying with nitrogen. The nitrogen may be present both as dissolved nitrogen and as nitride precipitate. It is well-known that the determination of low nitrogen content by means of X-ray microprobe analyses (EMPA) is not easy, consequently it seemed only logical to try to perform these measurements with the method of Auger electron spectroscopy ( AES) which is more sensitive as far as detection of light elements is concerned. After determining the line shape and line position of the nitrogen KLL-peak the detection limit was calculated at 0.02 at .% using …

Studies Of Intestinal Lymphoid Tissue. Xi – The Immunopathology Of Cell-Mediated Reactions In Gluten Sensitivity And Other Enteropathies, Michael N. Marsh

Scanning Microscopy

Computerised image-analysis was used to quantitate small intestinal mucosae from celiac sprue and dermatitis herpetiformis patients, Gambian children with tropical-sprue-like malabsorption, first-degree celiac sprue relatives, and treated celiac sprue patients during challenge with a peptic-tryptic digest of gluten. A wide range of mucosal appearances was observed. Typically, 'flat' lesions (Type 2) revealed a reduced number of epithelial lymphocytes that were large and mitotically active. At the other extreme, mucosal architecture was relatively well preserved (Type 1) but surface epithelium contained an expanded population of small, non-mitotic lymphocytes, with or without crypt hyperplasia. Similar changes were observed in one-third of celiac …