| Edge Technique Lidar for High Accuracy, High Spatial Resolution Wind Measurement in the Planetary Boundary Layer |
01 JUL 95 |
29 pages |
| Authors:
C. L. Korb; Bruce M. Gentry; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
 | The goal of the Army Research Office Geosciences program is to measure the three dimensional wind field in the planetary boundary layer (PBL) over a measurement volume with a 5O meter spatial resolution and with measurement accuracies of the order of 20 cm/sec. The objective of this work is to develop and evaluate a high vertical resolution lidar experiment using the edge technique for high accuracy measurement of the atmospheric ... |
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| Proceedings of the Annual Precise Time and Time Interval (PTTI) applications and Planning Meeting (25th) Held in Marina Del Rey, California on 29 November - 2 December 1993 |
02 DEC 93 |
589 pages |
| Authors:
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| An Operational Control Segment (OCS) Update on GPS Constellation Status and Future Program Directions, |
02 DEC 1993 |
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| Authors:
Harrison C. Freer; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
 | We run the GPS Master Control Station from the Second Space Operation Squadron out of Falcon Air Force Base, Colorado. This is our squadron symbol (Figure 1); the real story here is a big success story in terms of where GPS has gone and especially how PTTI applications have been so much a big part of GPS and how much a part of PTTI that GPS has become. They asked ... |
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| Two-Way Satellite Time Transfer: Overview and Recent Developments, |
02 DEC 1993 |
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| Authors:
Gerrit De Jong; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| The experiment using small earth stations for transatlantic two-way satellite time transfer between the USA (USNO, Washington, DC) and Germany (DFVLR), Oberfaffenhofen) has had its 10th anniversary this year. Pseudo Random Noise coded time signals were phase modulated and demodulated at each stations using a modem developed by Professor Hartl and his staff. Recently, during the last two weeks of August 1993, six European time laboratories have used the INTELSAT ... |
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| GPS Common - View Time Transfer, |
02 DEC 1993 |
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| Authors:
W. Lewandowski; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| The introduction of the GPS common-view method at the beginning of the 1980s led to an immediate and dramatic improvement of international time comparisons. Since then further progress brought the precision and accuracy of GPS common-view intercontinental time transfer, from tens of nanoseconds to a few nanoseconds, even with SA activated. This achievement was made possible, mainly by the use of ultra-precise ground antenna coordinates, post-processed precise ephemerides, double-frequency measurements ... |
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| Cascaded Clocks Measurement and Simulation Findings, |
02 DEC 1993 |
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| Authors:
Don Chislow; George Zampetti; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| This paper will examine aspects related to network synchronization distribution and the cascading of timing elements. Methods of timing distribution have become a much debated topic in standards forums and among network service providers (both domestically and internationally). Essentially these concerns focus on the need to migrate their existing network synchronization plans (and capabilities) to those required for the next generation of transport technologies (namely, the Synchronous Digital Hierarchy (SDH), ... |
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| The Use of the AOA TTR-4P GPS Receiver in Operation at the BIPM for Real-Time Restitution of GPS Time, |
02 DEC 1993 |
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| Authors:
Claudine Thomas; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| The Global Positioning System is an outstanding tool for the dissemination of time. Using mono-channel C/A-code GPS time receivers, the restitution of GPS time through the satellite constellation presents a peak-to-peak discrepancy of several tens of nanoseconds without SA but may be as high as several hundreds of nanoseconds with SA. As a consequence, civil users are more and more interested in implementary hardware and software methods for efficient restitution ... |
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| Development of an Accurate Transmission Line Fault Locator Using the Global Positioning System Satellites, |
02 DEC 1993 |
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| Authors:
Harry Lee; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| A highly accurate transmission line fault locator based on the traveling-wave principle has been developed and successfully operated within B.C. Hydro. A transmission line fault produces a fast-risetime traveling wave at the fault point which propagates along the transmission line. This fault locator system consists of traveling wave detectors located at key substations which detect and time tag the leading edge of the fault-generated traveling wave as it passes through. ... |
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| A Real-Time Prediction of UTC, |
02 DEC 1993 |
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| Authors:
Claudine Thomas; David W. Allan; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| The reference time scale for all scientific and technologic applications on the Earth, the Universal Coordinated Time UTC, must be as stable, reliable and accurate as possible. With this in view the BIPM and before it the BIH, have always calculated and then disseminated UTC with a delay of about 80 days. There are three fundamental reasons for doing this. (1) It takes some weeks for data, gathered from some ... |
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| Time Transfer Using Geostationary Satellites: Implementation of Kalman Filter, |
02 DEC 1993 |
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| Authors:
F. Meyer; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| Since 1988, various experiments 1, 2, 3, 4 have shown that the TV signals transmitted by direct TV satellites may easily be used to perform time transfers at the level of a few tens of nanoseconds, the main source of error being the uncertainty on the satellite position. We first present the two methods used in our experiment to reduce the effects of the satellite residual motion : the first ... |
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| Cesium and Rubidium Frequency Standards Status and Performance on the GPS Program, |
02 DEC 1993 |
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| Authors:
M. J. Van Melle; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| This paper is an update of the on-orbit operational performance of the frequency standards on the Block I GPS 8 to 11 Navstar satellites, the Block 11 GPS 13 to 21 Navstar satellites and the Block IIA GPS 22 to 40 Navstar satellites. A brief history of the frequency standards depicting improvements incorporated in the GPS Program with corresponding results will be presented. The frequency standards configurations from the start ... |
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| Noise and Drift Analysis of Non-Equally Spaced Timing Data, |
02 DEC 1993 |
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| Authors:
F. Vernotte; G. Zalamansky; E. Lantz; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| Generally, it is possible to obtain equally spaced timing data from oscillators. The measurement of the drifts and noises affecting oscillators, is then performed by using a variance (Allan variance, modified Allan variance, Time variance) or a system of several variances (multivariance method 1, 2). However, in some cases, several samples, or even several set of samples, are missing. In the case of millisecond pulsar timing data, for instance, observations ... |
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| An Algorithm for the Italian Atomic Time Scale, |
02 DEC 1993 |
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| Authors:
F. Cordara; G. Vizio; P. Tavella; V. Pettiti; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| During the past twenty years, the time scale at the IEN has been realized by a commercial cesium clock, selected from an ensemble of five, whose rate has been continuously steered towards UTC to maintain a tong term agreement within 3 x 10-13. A time scale algorithm, suitable for a small clock ensemble and capable of improving the medium and long term stability of the IEN time scale, has been ... |
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| Precision Frequency Synthesizing Sources with Excellent Time/Frequency Performances, |
02 DEC 1993 |
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| Authors:
Liren Zhou; Hai Lin; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| Precision frequency synthesizing sources are needed in the time/ frequency measuring system, atomic frequency standards, telemetry, communication and radar systems. This kind of frequency synthesizing sources possesses high frequency accuracy and excellent long term and short term frequency stability. Several precision frequency synthesizing sources developed by Beijing Institute of Radio Metrology and Measurement (BIRMM) are described in this paper, which have been successfully applied to the time / frequency measuring ... |
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| Measurement of the Frequency Stability of Responders in Aircraft, |
02 DEC 1993 |
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| Authors:
Xiaofan Liu; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| Measurement on an aircraft orbit, such as a satellite launching orbit, is made by the responder in the aircraft along with several remote track stations on the ground. During the launching, the system is required to have precise time synchronization and frequency accuracy. At the same time, accurate measurement of aircraft velocity requires high frequency stability of the system. However, atomic frequency standards in the ground stations supply time and ... |
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| TIme Synchronized Video Systems, |
02 DEC 1993 |
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| Authors:
Ron Burnett; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| The idea of synchronizing multiple video recordings to some type of 'range' time has been tried to varying degrees of success in the past. Combining this requirement with existing time code standards (SMPTE) and the new innovations in desktop multi-media however, have afforded an opportunity to increase the flexibility and usefulness of such efforts without adding costs over the traditional data recording and reduction systems. The concept described can use ... |
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| Hydrogen Maser Clocks in Space for Solid-Earth Research and Time-Transfer Applications: Experiment Overview and Evaluation of Russian Miniature Sapphire Loaded Cavity, |
02 DEC 1993 |
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| Authors:
G. Busca; L. G. Bernier; P. Silvestrin; S. Feltham; B. A. Gayerov; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| The Observatoire Cantonal de Neuchatel (ON) is developing for ESTEC a compact H-maser for space use based upon a miniature sapphire loaded microwave cavity, a technique pioneered at VNIIFTRI. Various contacts between West-European parties, headed by ESA, and the Russian parties, headed by RSA, Led to the proposal for flying two H-masers on Meteor 3M, a Russian meteorology satellite in low polar orbit. The experiment will include two masers, one ... |
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| Russian National Time Scale Long-Term Stability, |
02 DEC 1993 |
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| Authors:
A. P. Al'shina; B. A. Gaigerov; N. B. Koshelyaevsky; S. B. Pushkin; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| The Institute of Metrology for Time and Space NPO VNIIFTRI generates the National Time Scale (NTS) of Russia - one of the most stable time scales in the world. Its striking feature is that it is based on a free ensemble of H-masers only. During last two years the estimations of NTS longterm stability based only on H-masers intercomparison data gives a flicker floor of about (2 approx. 3) x ... |
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| Using GLONASS Signal for Clock Synchronization, |
02 DEC 1993 |
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| Authors:
Yuri G. Gouzhva; Arvid G. Gevorkyan; Pyotr P. Bogdanov; Vitaly V. Ovchinnikov; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| Although in accuracy parameters GLONASS is correlated with GPS, using GLONASS signals for high-precision clock synchronization was up to the recent time of limited utility due to the lack of specialized time receivers. In order to improve this situation, in late 1992 the Russian Institute of Radionavigation and Time (RIRT) began to develop a GLONASS time receiver using as a basis the airborne ASN-16 receiver. This paper presents results of ... |
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| Annual Precise Time and Time Interval (PTTI) Applications and Planning Meeting (24th) Held in McLean, VA on December 1-3, 1992 |
JUN 93 |
471 pages |
| Authors:
Richard L. Sydnor; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| Automated Inspection of Solder Joints for Surface Mount Technology. |
MAR 1993 |
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| Authors:
R. M. Savage; H. S. Park; M. S. Fan; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| Researchers at NASA/GSFC evaluated various automated inspection systems (AIS) technologies using test boards with known defects in surface mount solder joints. These boards were complex and included almost every type of surface mount device typical of critical assemblies used for space flight applications: X-ray radiography; X-ray laminography; Ultrasonic Imaging; Optical Imaging; Laser Imaging; and Infrared Inspection. Vendors, representative of the different technologies, inspected the test boards with their particular machine. ... |
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| An Analysis of the Crack Tip Fields in a Ductile Three-Point Bend Specimen Subjected to Impact Loading |
1993 |
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| Authors:
Timothy Premack; Andrew S. Douglas; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| Results of an impact fracture test of a precracked HY100 steel were analyzed to determine the dynamic fracture toughness. The crack tip opening displacement (CTOD) 100 microns behind the crack tip was measured. A numerical simulation of the fracture event was conducted to obtain relevant near crack tip field parameters. The specimen was modeled by a plane stress finite element simulation using a rate sensitive elastoplastic material law. |
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| Strengths and Weaknesses of Sea Ice as a Potential Early Indicator of Climate Change, |
MAR 1992 |
|
| Authors:
Claire L. Parkinson; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| Sea ice is examined for its potential as an early indicator of climate change by considering how well it satisfies four criteria listed as desired characteristics for potential early indicators. Results of numerical modeling studies in the 1970s and 1980s suggested that sea ice satisfies the first characteristic, that the variable be expected to exhibit a large climate signal, very well; but these results have recently been updated in a ... |
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| Variations of Extent, Area, and Open Water of the Polar Sea Ice Covers: 1978-1987, |
MAR 1992 |
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| Authors:
Per Gloersen; William J. Campbell; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| The Scanning Multichannel microwave Radiometer (SMMR) which operated onboard the Nimbus-7 satellite from October 1978 to August 1987 obtained sequential synoptic observations of the entire Arctic and Antarctic sea ice covers every 2 days through the clouds during night and day. It is a unique almost decade-long data set of the large-scale behavior of sea ice on earth. Ibis paper presents the results of an analysis of SMMR observations of ... |
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| Interannual Variability of Monthly Sea Ice Distributions in the North Polar Region, |
MAR 1992 |
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| Authors:
Claire L. Parkinson; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| Passive-microwave data from the Nimbus 5 and Nimbus 7 satellites have been used to determine and map, by month, the interannual variability of the spatial distribution of north polar sea ice over the period 1973-1987. Results are illustrated for the months of January and July, during the winter ice growth and summer ice decay seasons, respectively. In January, the greatest interannual variability in the distribution of the ice occurs in ... |
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| Acoustic Emission Monitoring of Low Velocity Impact Damage in Graphite/ Epoxy Laminates During Tensile Loading |
FEB 92 |
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| Authors:
Bradford H. Parker; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| An acoustic emission (AE) system was set up in a linear location in data acquisition mode to monitor the tensile loading of eight-ply quasi- isotropic graphite/epoxy specimens containing low velocity impact damage. The impact damage was induced using an instrumented drop weight tower. During impact, specimens were supported by either an aluminum plate or a membrane configuration. Cross-sectional examinations revealed that the aluminum plate configuration resulted in primarily matrix cracking ... |
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| Proceedings of Annual Precise Time and Time Interval (PTTI) Applications and Planning Meeting (23rd) held in Pasadena, California on December 3 - 5, 1991 |
05 DEC 91 |
459 pages |
| Authors:
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| This document is a compilation of technical papers presented at the 23rd Annual PTTI Applications and Planning Meeting, December 3 through 5, 1991, at the Ritz-Carlton Huntington Hotel in Pasadena, California. Papers are in the following categories. Recent developments in rubidium, cesium, and hydrogen- based frequency standards, and in cryogenic and trapped-ion technology. International and transnational applications of precise time and time interval technology with emphasis on satellite laser tracking ... |
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| An Initial Analysis of the Data from the Polar Orbiting Geophysical (POGS) Satellite |
NOV 91 |
24 pages |
| Authors:
R. A. Langel; T. J. Sabaka; R. T. Baldwin; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| The POGS (Polar Orbiting Geophysical Satellite) was launched in 1990 to measure the geomagnetic field. POGS data from selected magnetically quiet days was selected, quality checked and deleted were thought to be erroneous. A time-and-position correction was applied. The resulting data was fit to a degree 13 spherical harmonic model. Evaluation of the quality of the data indicates that it is sufficient for definition of the low-degree (say, less than ... |
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| Proceedings of the Annual Precise Time and Time Interval (PTTI) applications and Planning Meeting (22nd) Held in Vienna, Virginia on 4-6 Dec 1990 |
MAY 91 |
640 pages |
| Authors:
Richard L. Sydnor; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| The first successful magnetic resonance experiments were those of Rabi and his associates with molecular beams in 1938. The initial experiments measured the interactions of nuclear magnetic moments with external magnetic fields, but radiofrequency spectra were soon observed that depended on internal interactions within molecules atoms. Some of the radiofrequency spectra lines were almost independent of external conditions and could therefore be used as the highly stable periodic component of ... |
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| Airborne Lidar for Profiling of Surface Topography. |
JAN 1991 |
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| Authors:
J. L. Bufton; J. B. Garvin; J. F. Cavanaugh; L. Ramosizquierdo; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| Outgassing Data for Selecting Spacecraft Materials, |
NOV 1990 |
|
| Authors:
William A. Campbell; John J. Scialdone; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| Outgassing data, derived from tests at 398 K (125 deg C) for 24 hours in vacuum as per ASTM E 595-84, were compiled for numerous materials for spacecraft use. The data presented are the total mass loss (TML) and the collected volatile condensable materials (CVCM). The various materials are compiled by likely usage, and then in alphabetical order. (Author). |
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| Wideband Noise Observed at Ground-Level in the Auroral Region, |
03 MAY 1990 |
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| Authors:
Robert F. Benson; Michael D. Desch; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| A wideband noise event was detected at ground level from the Andoya Rocket Range in Norway in January 1989. The signals were observed using 4 commercial communication receivers (tuned to 159, 515, 905 and 1200 kHz), an ionosonde (200 kHz to 3.5 MHz interference-free observations) and a riometer (32.5 MHz). The event, which occurred during a period of magnetic disturbance near magnetic midnight, was the only one observed during nearly ... |
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| Fracture Toughness and Crack Growth of Zerodur |
APR 90 |
27 pages |
| Authors:
MIchael J. Viens; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| The fracture toughness and crack growth parameters of Zerodur, a low expansion glass ceramic material, were determined. The fracture toughness was determined using indentation techniques and was found to be 0.9 MPa.m1/2. The crack growth parameters were determined using indented biaxial specimens subjected to static and dynamic loading in an aqueous environment. The crack growth parameters n and ln(B) were found to be 30.7 and -6.837, respectively. The crack growth ... |
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| Fracture Toughness and Crack Growth of Zerodur, |
APR 1990 |
|
| Authors:
Michael J. Viens; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| The fracture toughness and crack growth parameters of Zerodur, a low expansion glass ceramic material, were determined. The fracture toughness was determined using indentation techniques. The crack growth parameters were determined using indented biaxial specimens subjected to static and dynamic loading in an aqueous environment. The crack growth parameters were also determined using indented biaxial specimens subjected to dynamic loading in an ambient 50% relative humidity environment. (Author, modified). |
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| Self-Calibration of Robot-Sensor System. |
FEB 1990 |
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| Authors:
P. Yeh; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| The process of finding the coordinate transformation between a robot and an external sensor system has been addressed. This calibration is equivalent to solving a nonlinear optimization problem for the parameters that characterize the transformation. A two-step procedure is herein proposed for solving the problem. The first step involves finding a nominal solution that is a good approximation of the final solution. A variational problem is then generated to replace ... |
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| Thermomechanical Properties of Polymeric Materials and Related Stresses, |
1990 |
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| Authors:
Sheng Y. Lee; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| The properties of a number of widely used polymeric materials were determined by thermomechanical analysis and dynamic mechanical analysis. A combined profile of the coefficient of thermal expansion (CTE) and the modulus change over a wide temperature range obtained by the analyses shows clearly the drastic effect of the glass transition on both the CTE and the modulus of a polymer, and the damaging potential due to such effect. (Author). ... |
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| Processing of DMSP Magnetic Data and Its Use in Geomagnetic Field Modeling |
NOV 89 |
63 pages |
| Authors:
J. R. Ridgway; T. J. Sabaka; D. Chinn; R. A. Langel; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| The DMSP F-7 satellite is an operational Air Force meteorological satellite which carried a magnetometer for geophysical measurements. The magnetometer was located within the body of the spacecraft in the presence of large spacecraft fields. In addition to stray magnetic fields, the data have inherent position and time inaccuracies. Algorithms were developed to identify and remove time varying magnetic field noise from the data. Techniques developed for Magsat were then ... |
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| Workshop on Two-Phase Fluid Behavior in a Space Environment, |
JUL 1989 |
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| Authors:
Theodore D. Swanson; Al Juhasz; W. R. Long; Laura Ottenstein; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| This document addresses the results and observations generated at a national workshop on two-phase fluid behavior in a space environment. The Workshop was successful in achieving its main objective of identifying a large number of technical issues relating to the design of two-phase systems for space applications. The principal concern expressed was the need for verified analytical tools that will allow an engineer to confidently design a system to a ... |
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| Interferometric Phase Measurement of Zerodur, Aluminum and SXA Mirrors at Cryogenic Temperatures |
88 |
|
| Authors:
Thomas J. Magner; Richard D. Barney; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| Th surface figure error of several different types of mirrors at cryogenic temperatures was studied in a research program. fabricated from zerodur, aluminum and a metal matrix composite of silicon carbide reinforced aluminum(sxa) were two-inch diameter parabolic, spherical and flat mirrors. in order that the coefficient of thermal expansion(cte) of the metal matrix matched electroless nickel, the ratio of silicon carbide to aluminum was carefully selected. a liquid helium dewar ... |
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| Evaluation of Multilayer Printed Wiring Boards by Metallographic Techniques. An Illustrated Guide to the Preparation and Inspection of Plated- Through Hole Test Coupons Based on the Requirements of MIL-P-55llOD |
MAY 86 |
73 pages |
| Authors:
Jane Jellison; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| This work is an illustrated handbook containing the rationale and procedure for the evaluation of multilayer printed wiring board construction integrity with respect to plated-through holes in accordance with the requirements of MIL-P-55l lOD, "Printed Wiring Boards." Itis intended as a practical aid for those concerned with determining the construction integrity of multilayer boards for high reliability applications. Photomicrographs of cross- sectioned holes illustrate defect types, acceptable and unacceptable conditions, ... |
|
| Mass Spectrometry of Aerospace Materials |
JUN 76 |
20 pages |
| Authors:
J. A. Colony; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| Mass spectrometry is used for chemical analysis of aerospace materials and contaminants. Years of analytical aerospace experience have resulted in the development of specialized techniques of sampling and analysis which are required in order to optimize results. This work has resulted in the evolution of a hybrid method of indexing mass spectra which includes both the largest peaks and the structurally significant peaks in a concise format. With this system, ... |
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| Precise Time Dissemination Experiment Using the ATS-1 Satellite. |
OCT 1975 |
|
| Authors:
A. R. Chi; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| A precise time transfer experiment using the Application Technology Satellite (ATS) as a link between a master and slave station achieved an accuracy of 50 nanoseconds one sigma. The technique is inherently capable of transferring precise time on a real time basis from a master time station to a number of slave stations. A conventional pseudo random noise (PN) code is used because of its spread spectrum properties. The low ... |
|
| Outgassing Data for Spacecraft Materials. |
JUL 1975 |
162 pages |
| Authors:
William A. Campbell Jr.; Richard S. Marriott; John J. Park; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| Outgassing data, derived from tests at 398 K (1250 C) for 24 hours in vacuum, have been compiled for numerous materials for spacecraft use. The data presented are the total mass loss (TML) and the collected volatile condensable materials (CVCM). The various materials are compiled by likely usage and alphabetically. (AN) |
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| The Effects of Particle Size on the Optical Properties and Surface Roughness of a Glass-Balloon-Filled Black Paint |
MAY 74 |
13 pages |
| Authors:
Thomas Heslin; James Heaney; Marvin Harper; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| The effects of particle size on the optical properties and surface roughness of a glass balloon filled, carbon pigmented paint were studied in order to develop a diffuse reflecting, low total reflectance, low outgassing black paint. Particle sizes ranged between < 2O microns and 74 microns. Surface roughness was found to increase with increasing particle size. Relative total reflectance at near normal incidence (MgO standard) of the filled paints was ... |
|
| A Compilation of Outgassing Data for Spacecraft Materials |
SEP 73 |
199 pages |
| Authors:
William A. Campbell Jr.; Richard S. Marriott; John J. Park; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| Outgassing data, consisting of percentage weight loss and percentage volatile condensable materials, have been compiled from results obtained at Goddard Space Flight Center and at Stanford Research Institute. The data are assembled categorically and alphabetically to aid materials engineers, designers, and manufacturers in selecting materials with low outgassing properties. |
|
| Achievement of a Low-Outgassing White Paint System for Spacecraft Thermal Control |
AUG 72 |
17 pages |
| Authors:
Benjamin Seidenberg; John J. Park; Carroll Clatterbuck; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| Test results and data for achieving a low-outgassing polymer resin suitable for potting or as a vehicle for a paint pigment are presented. The resin, prepared in O.5-kg (1 -lb) batches, is acceptable for spacecraft use; its weight loss is less than 0.5 percent and the volatile condensable materials are less than 0.05 percent. The paint adheres well to a primed fiber glass or aluminum substrate. Results of UV irradiation, ... |
|
| Analysis of Surveyor III Television Cable After Residence on the Moon |
MAR 72 |
14 pages |
| Authors:
Frederick C. Gross; John J. Park; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
|
| The Apollo 12 astronauts brought the Surveyor III television camera back from the moon in November 1969. Chemical analyses of a portion of television cable revealed changes in the glass fabric sleeve and in the wire insulation as a result of exposure to the lunar environment. Loss of volatile constituents from the glass fabric and a discoloration of the glass occurred. The Teflon layer on the wire showed a slight ... |
|
| Visual Appearance of Polymeric Contamination |
JUN 70 |
16 pages |
| Authors:
Harold Shapiro; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| This paper presents a series of photomicrographs which shows the condensate that a selected group of polymers might have if they were present as spacecraft contaminants. Nine classes of polymeric materials were subjected to temperature and vacuum conditions, and, using microscopic techniques, the condensed effluents were observed. Outgassing data are presented for some materials in the form of weight loss. Photographic material is presented for seven classes; however, for the ... |
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| Criteria for Selection of Wire Insulations for Use in Space Applications |
JUL 68 |
20 pages |
| Authors:
Vernon Krueger; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| The properties of five electrical insulation materials were compared, to provide a guide for selecting wire insulations in spacecraft. Of all the properties considered, the outgassing characteristics, radiation resistance, and weight of the materials were considered most important for space applications. Also considered were the workability of these insulations and the amount of fabrication deterioration that wires and cables using them can withstand. |
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| Mechanical and Physical Properties of the Echo II Metal-Polymer Laminate |
AUG 66 |
43 pages |
| Authors:
C. L. Staugaitis; L. Kobren; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER
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| Results of a comprehensive investigation of the physical and mechanical properties of the Echo II material are reported. The Echo II material (an aluminum - mylar - aluminum composite film) was subjected to a variety of tests and environmental controls designed to evaluate its properties under anticipated service conditions. This test program included the determination of creep and relaxation properties, peel strength, electrical conductivity, and uniaxial and biaxial stress properties. ... |
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