Description of the Mast Flight System

The Mast Flight System is composed of several subsystems. Primary among these is the Deployable Mast Subsystem (DMS) which consists of a beam assembly and an associated mechanism for deploying and retracting the beam. The beam assembly is a joint dominated graphite epoxy and titanium truss as is expected of future large space structures. Integral to the beam assembly are actuators, sensors and associated electronics which are available for excitation and damping as desired by the experimenter. The beam structural characteristics can also be modified as desired by the experimenter using the Parameter Modification Device installed at the end of the beam. Data measured on the beam by the sensors and commands to the actuators are transmitted along the beam digitally at 150 Hz using a standard 1553 type bus. The Modular Distributed Information Sybsystem (MDIS) computer functions as bus master and ensures that all experimental data is saved for future analysis. The MDIS computer also performs a safing function to prevent inadvertent overexcitation of the beam. Finally, the Excitation and Damping Subsystem (EDS) computer is available to the experimenter for implementation of control algorithms or any other numerical operations as desired. Data from all system sensors can be accessed by the EDS computer

Mast flight system beam structure and beam structural performance

An overall understanding of the beam assembly and data with which potential experimenters can begin to conduct analyses relevant to their experiments is given. Data is given on the beam structural concept, the tip remote station layout, the intermediate remote station layout with and without actuators, beam element materials, equivalent beam characteristics, beam element properties, remote station mass properties, and MAST Flight System modal characteristics

Global meteorological data facility for real-time field experiments support and guidance

A Global Meteorological Data Facility (GMDF) has been constructed to provide economical real-time meteorological support to atmospheric field experiments. After collection and analysis of meteorological data sets at a central station, tailored meteorological products are transmitted to experiment field sites using conventional ground link or satellite communication techniques. The GMDF supported the Global Tropospheric Experiment Amazon Boundary Layer Experiment (GTE-ABLE II) based in Manaus, Brazil, during July and August 1985; an arctic airborne lidar survey mission for the Polar Stratospheric Clouds (PSC) experiment during January 1986; and the Genesis of Atlantic Lows Experiment (GALE) during January, February and March 1986. GMDF structure is similar to the UNIDATA concept, including meteorological data from the Zephyr Weather Transmission Service, a mode AAA GOES downlink, and dedicated processors for image manipulation, transmission and display. The GMDF improved field experiment operations in general, with the greatest benefits arising from the ability to communicate with field personnel in real time

Investigation of potential of differential absorption Lidar techniques for remote sensing of atmospheric pollutants

The NASA multipurpose differential absorption lidar (DIAL) system uses two high conversion efficiency dye lasers which are optically pumped by two frequency-doubled Nd:YAG lasers mounted rigidly on a supporting structure that also contains the transmitter, receiver, and data system. The DIAL system hardware design and data acquisition system are described. Timing diagrams, logic diagrams, and schematics, and the theory of operation of the control electronics are presented. Success in obtaining remote measurements of ozone profiles with an airborne systems is reported and results are analyzed

Acoustic spectral analysis and testing techniques

Subjects covered in four reports are described including: (1) mathematical techniques for combining decibel levels of octaves or constant bandwidth: (2) techniques for determining equation for power spectral density function; (3) computer program to analyze acoustical test data; and (4) computer simulation of horn responses utilizing hyperbolic horn theory

“Such a section as never was put together before”: Logan, Dawson, Lyell, and mid-Nineteenth-Century measurements of the Pennsylvanian Joggins section of Nova Scotia

William Edmond Logan assumed his duties as the first head of the Geological Survey of Canada in June 1843. Two previously overlooked field notebooks provide new insight into his first field project that summer: measurement of the “Joggins section,” a classic Carboniferous locality in Nova Scotia. Inspired by reports of 40-foot-tall fossil trees, Logan spent five days measuring 14 570 feet 11 inches of strata exposed along the shore of the Bay of Fundy. Widely regarded as a meticulous, bed-by-bed measured section, closer examination reveals that many thickness values were calculated using paced distances. Realizing that his measured section was too detailed for scientific journals of the day, Logan published his work in a relatively obscure government publication where it went largely unnoticed for nearly a decade. Unaware of Logan’s measured section, John William Dawson and Charles Lyell visited Joggins in 1852 and measured the section for themselves. Dawson later stated that the two sections contain only minor differences, but careful comparison shows that they have radically different descriptions and measurements for even the most distinctive beds. Dawson disguised these discrepancies in post-1855 editions of his book Acadian Geology by rewriting much of the measured section and abandoning many of his own observations. Although over 200 subsequent Joggins studies build upon these measured sections, the present study represents the first detailed examination of the two historical sections and reveals previously unknown discrepancies between two of the most important early geologic studies undertaken in Nova Scotia. Resumé William Edmond Logan est devenu le premier responsable de la Commission géologique du Canada en juin 1843. Deux carnets de travaux sur le terrain, précédemment négligés, fournissent un nouvel éclairage sur son premier projet sur le terrain cet été-là : le mesurage du « stratotype de Joggins », un secteur carbonifère classique en Nouvelle-Écosse. Inspiré par des comptes rendus de la présence d’arbres fossiles de 40 pieds de hauteur, Logan a consacré cinq jours à mesurer 14 570 pieds 11 pouces de strates affleurant le long du rivage de la baie de Fundy. Un examen plus attentif de l’endroit, largement considéré comme un stratotype méticuleusement mesuré couche par couche, révèle que de nombreuses données d’épaisseur ont été calculées au nombre de pas. Se rendant compte que le stratotype qu’il avait mesuré était trop détaillé pour les revues scientifiques de l’époque, Logan avait publié ses travaux dans une publication gouvernementale relativement obscure où ils sont demeurés pratiquement inaperçus pendant près d’une décennie. John William Dawson et Charles Lyell, qui n’étaient pas au courant du stratotype mesuré par Logan, se sont rendus à Joggins en 1852 et ont mesuré le stratotype eux-mêmes. Dawson a ultérieurement laissé entendre que les deux stratotypes présentaient seulement des différences minimes, mais une comparaison attentive révèle que leurs descriptions et leurs mesures sont radicalement différentes, même dans le cas des couches les plus caractéristiques. Dawson a déguisé ces divergences dans des éditions ultérieures à 1855 de son livre Acadian Geology en remaniant une vaste part du stratotype mesuré et en abandonnant nombre de ses propres observations. Même si plus de 200 études subséquentes de Joggins se sont appuyées sur les stratotypes mesurés, la présente étude représente le premier examen détaillé des stratotypes et elle révèle des divergences auparavant inconnues entre deux des premières études géologiques les plus importantes réalisées en Nouvelle-Écosse. [Traduit par la rédaction