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At least 433 records · Page 24

Unified Optimization Of A Structure And Its Control System

Method for unified optimization of structure and its vibration-suppressing control system involves extension of established techniques of optimization via approach based on homotopy, in which cost function used as criterion for optimization of control system coupled to corresponding cost function of structure via new parameter. Applicable to such terrestrial problems as designing buildings with control actuators to prevent damage by earthquakes.

Milman, Mark H.↗

The NASA SETI program

In 1959, it was proposed that a sensible way to conduct interstellar communication would be to use radio at or near the frequency of hydrogen. In 1960, the first Search for Extraterrestrial Intelligence (SETI) was conducted using a radiotelescope at Green Bank in West Virginia. Since 1970, NASA has systematically developed a definitive program to conduct a sophisticated search for evidence of extraterrestrial intelligent life. The basic hypothesis is that life may be widespread in the univers, and that in many instances extraterrestrial life may have evolved into technological civilizations. The underlying scientific arguments are based on the continuously improving knowledge of astronomy and astrophysics, especially star system formation, and of planetary science, chemical evolution, and biological evolution. If only one in a million sun-like stars in our galaxy harbors species with cognitive intelligence, then there are 100,000 civilizations in the Milky Way alone. The fields of radioastronomy digital electronic engineering, spectrum analysis, and signal detection have advanced rapidly in the last twenty years and now allow for sophisticated systems to be built in order to attempt the detection of extraterrestrial intelligence signals. In concert with the scientific and engineering communities, NASA has developed, over the last several years, a Microwave Observing Project whose goal is to design, build, and operate SETI systems during the decade of the nineties in pursuit of the goal signal detection. The Microwave Observing Project is now approved and underway. There are two major components in the project: the Target Search Element and the Sky Survey Element.

Billingham, J.↗

Endoscopic inspection using a panoramic annular lens

The objective of this one year study was to design, build, and demonstrate a prototype system for cavity inspection. A cylindrical view of the cavity interior was captured in real time through a compound lens system consisting of a unique panoramic annular lens and a collector lens. Images, acquired with a digitizing camera and stored in a desktop computer, were manipulated using image processing software to aid in visual inspection and qualitative analysis. A detailed description of the lens and its applications is given.

Gilbert, John A.↗

Endoscopic measurements using a panoramic annular lens

The objective of this project was to design, build, demonstrate, and deliver a prototype system for making measurements within cavities. The system was to utilize structured lighting as the means for making measurements and was to rely on a stationary probe, equipped with a unique panoramic annular lens, to capture a cylindrical view of the illuminated cavity. Panoramic images, acquired with a digitizing camera and stored in a desk top computer, were to be linearized and analyzed by mouse-driven interactive software.

Gilbert, John A.↗

Vented Tank Resupply Experiment (VTRE) for In-space Technology Experiment Program (IN-STEP)

An overview of the Vented Tank Resupply Experiment (VTRE) program is presented in outline and graphical form. The goal of the program is to develop, design, build and provide flight and post flight support for a Shuttle Hitchhiker Experiment to investigate and demonstrate vented tank venting in space. Program schedules and experiment subsystem schematics are presented and specific technical objectives, power requirements, payload assemblies, Hitchhiker canister integration, and orbiter mission approach are addressed.

Source record↗

Interferometric tracking system for the tracking and data relay satellite

This report documents construction and testing of the Interferometric Tracking System project developed under the NASA SBIR contract NAS5-30313. Manuals describing the software and hardware, respectively entitled: 'Field Station Guide to Operations' and 'Field Station Hardware Manual' are included as part of this final report. The objective of this contract was to design, build, and operate a system of three ground stations using Very Long Baseline Interferometry techniques to measure the TDRS orbit. The ground stations receive signals from normal satellite traffic, store these signals in co-located computers, and transmit the information via phone lines to a central processing site which correlates the signals to determine relative time delays. Measurements from another satellite besides TDRS are used to determine clock offsets. A series of such measurements will ultimately be employed to derive the orbital parameters, yielding positions accurate to within 50 meters or possibly better.

Effland, John E.↗

ACE: A distributed system to manage large data archives

Competitive pressures in the oil and gas industry are requiring a much tighter integration of technical data into E and P business processes. The development of new systems to accommodate this business need must comprehend the significant numbers of large, complex data objects which the industry generates. The life cycle of the data objects is a four phase progression from data acquisition, to data processing, through data interpretation, and ending finally with data archival. In order to implement a cost effect system which provides an efficient conversion from data to information and allows effective use of this information, an organization must consider the technical data management requirements in all four phases. A set of technical issues which may differ in each phase must be addressed to insure an overall successful development strategy. The technical issues include standardized data formats and media for data acquisition, data management during processing, plus networks, applications software, and GUI's for interpretation of the processed data. Mass storage hardware and software is required to provide cost effective storage and retrieval during the latter three stages as well as long term archival. Mobil Oil Corporation's Exploration and Producing Technical Center (MEPTEC) has addressed the technical and cost issues of designing, building, and implementing an Advanced Computing Environment (ACE) to support the petroleum E and P function, which is critical to the corporation's continued success. Mobile views ACE as a cost effective solution which can give Mobile a competitive edge as well as a viable technical solution.

Daily, Mike I.↗

The Consolidated Planning and Scheduling System for Space Transportation and Space Station operations - Successful development experience

In 1992, NASA made the decision to evolve a Consolidated Planning System (CPS) by adding the Space Transportation System (STS) requirements to the Space Station Freedom (SSF) planning software. This paper describes this evolutionary process, which began with a series of six-month design-build-test cycles, using a domain-independent architecture and a set of developmental tools known as the Advanced Scheduling Environment. It is shown that, during these tests, the CPS could be used at multiple organizational levels of planning and for integrating schedules from geographically distributed (including international) planning environments. The potential for using the CPS for other planning and scheduling tasks in the SSF program is being currently examined.

Hornstein, Rhoda S.↗

A magnetic shield/dual purpose mission

The objective of this work is to design, build, and fly a dual-purpose payload whose function is to produce a large volume, low intensity magnetic field and to test the concept of using such a magnetic field to protect manned spacecraft against particle radiation. An additional mission objective is to study the effect of this moving field on upper atmosphere plasmas. Both mission objectives appear to be capable of being tested using the same superconducting coil. The potential benefits of this magnetic shield concept apply directly to both earth-orbital and interplanetary missions. This payload would be a first step in assessing the true potential of large volume magnetic fields in the U.S. space program. Either converted launch systems or piggyback payload opportunities may be appropriate for this mission. The use of superconducting coils for magnetic shielding against solar flare radiation during manned interplanetary missions has long been contemplated and was considered in detail in the years preceding the Apollo mission. With the advent of new superconductors, it has now become realistic to reconsider this concept for a Mars mission. Even in near-earth orbits, large volume magnetic fields produced using conventional metallic superconductors allow novel plasma physics experiments to be contemplated. Both deployed field-coil and non-deployed field-coil shielding arrangements have been investigated, with the latter being most suitable for an initial test payload in a polar orbit.

Watkins, Seth↗

SPICE: An innovative, flexible instrument concept

Studies and plans for orbital capture of cosmic dust and interplanetary dust particles (IDP's) looked very bright with the advent of space station Freedom (SSF) and formal selection of Cosmic Dust Collection Facility (CDCF) as an attached payload in 1990. Unfortunately it has been downhill since its selection, culminating in CDCF being dropped as attached payload in the SSF redesign process this year. This action was without any input from the science or cosmic dust communities. The Exobiology Intact Capture Experiment (Exo-ICE) as an experiment on CDCF was also lost. Without CDCF, no facility-class instrument for cosmic dust studies is available or planned. When CDCF (and Exo-ICE) was selected as a SSF attached payload, an exercise called the small particle intact capture experiment (SPICE) was started for Exo-ICE to develop an understanding and early testing of the necessary expertise and technology for intact capture of cosmic dust and IDP's. This SPICE activity looks to fly small, meter square or less, collection area experiments on early orbital platforms of opportunity such as EURECA, MIR, WESTAR, and others, including the shuttle. The SPICE activity has focused on developing techniques and instrument concepts to capture particles intact and without inadvertent contamination. It began with a survey and screening of available capture media concepts and then focused on the development of a capture medium that can meet these requirements. Evaluation and development of the chosen capture medium, aerogel (a silicon oxide gel), has so far lived up to the expectations of meeting the requirements and is highlighted in a companion paper at this workshop. Others such as McDonnell's Timeband Capture Cell Experiment (TICCE) on EuReCa and Tsuo's GAS-CAN lid experiments on STS 47 and 57 have flown aerogel, but without addressing the contamination issue/requirement, especially regarding organics. Horz, Zolenskym and others have studied and have also been advocates for its development. The SPICE instrument's experiment design builds on the knowledge gained from these efforts to meet the intact capture, noncontamination requirements. An overview of a possible SPICE experimental instrument concept using the MIR space station as a host platform for cosmic dust collection is provided in this paper. The SPICE concept is nonplatform-specified and can fly on any platform that provides a mode for experiment recovery.

Nishioka, Kenji↗

Comprehension and retrieval of failure cases in airborne observatories

This paper describes research dealing with the computational problem of analyzing and repairing failures of electronic and mechanical systems of telescopes in NASA's airborne observatories, such as KAO (Kuiper Airborne Observatory) and SOFIA (Stratospheric Observatory for Infrared Astronomy). The research has resulted in the development of an experimental system that acquires knowledge of failure analysis from input text, and answers questions regarding failure detection and correction. The system's design builds upon previous work on text comprehension and question answering, including: knowledge representation for conceptual analysis of failure descriptions, strategies for mapping natural language into conceptual representations, case-based reasoning strategies for memory organization and indexing, and strategies for memory search and retrieval. These techniques have been combined into a model that accounts for: (a) how to build a knowledge base of system failures and repair procedures from descriptions that appear in telescope-operators' logbooks and FMEA (failure modes and effects analysis) manuals; and (b) how to use that knowledge base to search and retrieve answers to questions about causes and effects of failures, as well as diagnosis and repair procedures. This model has been implemented in FANSYS (Failure ANalysis SYStem), a prototype text comprehension and question answering program for failure analysis.

Alvarado, Sergio J.↗

High-Flux, High-Temperature Thermal Vacuum Qualification Testing of a Solar Receiver Aperture Shield

As part of the International Space Station (ISS) Phase 1 program, NASA Lewis Research Center (LERC) and the Russian Space Agency (RSA) teamed together to design, build and flight test the world's first orbital Solar Dynamic Power System (SDPS) on the Russian space station Mir. The Solar Dynamic Flight Demonstration (SDFD) program was to operate a nominal 2 kWe SDPS on Mir for a period up to 1-year starting in late 1997. Unfortunately, the SDFD mission was demanifested from the ISS phase 1 shuttle program in early 1996. However, substantial flight hardware and prototypical flight hardware was built including a heat receiver and aperture shield. The aperture shield comprises the front face of the cylindrical cavity heat receiver and is located at the focal plane of the solar concentrator. It is constructed of a stainless steel plate with a 1-m outside diameter, a 0.24-m inside diameter and covered with high-temperature, refractory metal Multi-Foil Insulation (MFI). The aperture shield must minimize heat loss from the receiver cavity, provide a stiff, high strength structure to accommodate shuttle launch loads and protect receiver structures from highly concentrated solar fluxes during concentrator off-pointing events. To satisfy Mir operational safety protocols, the aperture shield was required to accommodate direct impingement of the intensely concentrated solar image for a 1-hour period. To verify thermal-structural durability under the anticipated high-flux, high-temperature loading, an aperture shield test article was constructed and underwent a series of two tests in a large thermal vacuum chamber configured with a reflective, point-focus solar concentrator and a solar simulator. The test article was positioned near the focal plane and exposed to concentrated solar flux for a period of 1-hour. In the first test, a near equilibrium temperature of 1862 K was attained in the center of the shield hot spot. In the second test, with increased incident flux, a near equilibrium temperature of 2072 K was achieved. The aperture shield sustained no visible damage as a result of the exposures. This paper describes the aperture shield thermal-vacuum qualification test program including the test article, test facility, procedures, data collection, test success criteria, results and conclusions.

Kerslake, Thomas W.↗

Rocket/Radar Investigation of Lower Ionospheric Electrodynamics Associated with Intense Midlatitude Sporadic-E Layers

Sporadic layers, which appear in the region from 100 km to 120 km are thought to be formed by convergent Pedersen drifts induced by altitude gradients in the zonal neutral wind. In this altitude region NO+ and 02+ are the major ions produced by photoionization and charge exchange of atmospheric and ionospheric species. The relative composition of atmospheric ions and meteoric ions in sporadic layers is important in determining their persistence, the time scales for formation, and the electrical conductivity of the layers. This rocket investigation will include a diagnosis of the neutral wind field and the electric field distribution. Coupled with ion composition measurements we will be able to expose the relevant formation mechanisms and the electrodynamic consequences of their existence. A rocket trajectory has been chosen to provide substantial horizontal sampling of the layer properties and knowledge of the horizontal gradients in composition and density are essential to determine the polarization electric fields that may be associated with ionospheric layers. The University of Texas at Dallas (UTD) is responsible for designing, building, and operating the ion mass spectrometers included on these rockets. The following provides a summary of the UTD accomplishments in the second year of the project as well as a description of the plans for the third year's activities. The UTD mass spectrometer acronym has been coined as PRIMS for Puerto Rico Ion Mass Spectrometer.

Heelis, R. A.↗

Miniature Heat Transport System for Nanosatellite Technology

The scientific understanding of key physical processes between the Sun and the Earth require simultaneous measurements from many vantage points in space. Nano-satellite technologies will enable a class of constellation missions for the NASA Space Science Sun-Earth Connections. This recent emphasis on the implementation of smaller satellites leads to a requirement for development of smaller subsystems in several areas. Key technologies under development include: advanced miniaturized chemical propulsion; miniaturized sensors; highly integrated, compact electronics; autonomous onboard and ground operations; miniatures low power tracking techniques for orbit determination; onboard RF communications capable of transmitting data to the ground from far distances; lightweight efficient solar array panels; lightweight, high output battery cells; lightweight yet strong composite materials for the nano-spacecraft and deployer-ship structures. These newer smaller systems may have higher power densities and higher thermal transport requirements than seen on previous small satellites. Furthermore, the small satellites may also have a requirement to maintain thermal control through extended earth shadows, possibly up to 8 hours long. Older thermal control technology, such as heaters, thermostats, and heat pipes, may not be sufficient to meet the requirements of these new systems. Conversely, a miniature two-phase heat transport system (Mini-HTS) such as a Capillary Pumped Loop (CPL) or Loop Heat Pipe (LBP) is a viable alternative. A Mini-HTS can provide fine temperature control, thermal diode action, and a highly efficient means of heat transfer. The Mini-HTS would have power capabilities in the range of tens of watts or less and provide thermal control over typical spacecraft ranges. The Mini-HTS would allow the internal portion of the spacecraft to be thermally isolated from the external radiator, thus protecting the internal components from extreme cold temperatures during an eclipse. The Mini-HTS would transport the beat from these components to a radiator during their operational modes, and it would be shutdown during non-operational or eclipse modes. Shutdown of the Mini-HTS would be accomplished with small heaters and has been successfully demonstrated on numerous occasions, both in the lab and on flight experiments. Efforts are now underway to miniaturize two-phase heat transport systems for the Nanosatellite project, with potential application to other small satellite programs. 'ne goal of this project is to design, build, and test miniature heat transport systems (MHTS) that would demonstrate the feasibility of a small Capillary Pumped Loop (CPL) or Loop Heat Pipe (LBP).

Douglas, Donya M,↗

Propulsion/ASME Rocket-Based Combined Cycle Activities in the Advanced Space Transportation Program Office

NASA's Office Of Aeronautics and Space Transportation Technology (OASTT) has establish three major coals. "The Three Pillars for Success". The Advanced Space Transportation Program Office (ASTP) at the NASA's Marshall Space Flight Center in Huntsville,Ala. focuses on future space transportation technologies under the "Access to Space" pillar. The Advanced Reusable Technologies (ART) Project, part of ASTP, focuses on the reusable technologies beyond those being pursued by X-33. The main activity over the past two and a half years has been on advancing the rocket-based combined cycle (RBCC) technologies. In June of last year, activities for reusable launch vehicle (RLV) airframe and propulsion technologies were initiated. These activities focus primarily on those technologies that support the year 2000 decision to determine the path this country will take for Space Shuttle and RLV. In February of this year, additional technology efforts in the reusable technologies were awarded. The RBCC effort that was completed early this year was the initial step leading to flight demonstrations of the technology for space launch vehicle propulsion. Aerojet, Boeing-Rocketdyne and Pratt & Whitney were selected for a two-year period to design, build and ground test their RBCC engine concepts. In addition, ASTROX, Pennsylvania State University (PSU) and University of Alabama in Huntsville also conducted supporting activities. The activity included ground testing of components (e.g., injectors, thrusters, ejectors and inlets) and integrated flowpaths. An area that has caused a large amount of difficulty in the testing efforts is the means of initiating the rocket combustion process. All three of the prime contractors above were using silane (SiH4) for ignition of the thrusters. This follows from the successful use of silane in the NASP program for scramjet ignition. However, difficulties were immediately encountered when silane (an 80/20 mixture of hydrogen/silane) was used for rocket ignition.

Hueter, Uwe↗

The Dipper Satellite: A Medium-Class Explorer Mission to the Threshold of Space

The Dipper satellite will carry out an unprecedented, systematic, and focused in-situ exploration of the Earth's lower ionosphere and thermosphere below 200 km that will produce a pivotal base of knowledge that will significantly advance our understanding of knowledge that will significantly advance our understanding of how our near-space environment works. The satellite will carry comprehensive in-situ probes to measure vector electric and magnetic fields, plasma density and temperature, ion velocities, ion and neutral composition and winds, energetic particles including suprathermal electrons, gravity waves, and lightning bursts. The satellite will include a propulsion system and tapered body that will provide over 10,000 excursions to altitudes below 200 km with over 3000 dips to altitudes below 150 km. With this instrument complement, spacecraft, and orbit, the Dipper mission will gather the necessary combined electrodynamics and neutral dynamics measurements to provide an understanding of the Earth's critical boundary region where the ionized gases of space and the neutral gases of the atmosphere are coupled, and where impinging forces and momentum are deposited from the magnetosphere above and from the troposphere, stratosphere, and mesosphere below. In exploring those physical processes in the lower ionosphere which can only be measured in-situ, the Dipper mission addresses four main science objectives. The Dipper will: 1) reveal how ion-neutral coupling creates a global system of dynamo electric fields and currents; 2) provide first-hand understanding of how magnetospheric currents close in the ionosphere and reveal the effects on the upper atmosphere of magnetospheric energy and momentum deposition; 3) discover the degree of upwards coupling and energy deposition due to thunderstorm electric fields and determine their significance; 4) determine the dynamics and composition of the Earth's lower thermosphere, including its response to gravity, tidal, and planetary waves on a range of spatial scales. A proposal to design, build, operate, and analyze data from instruments on the Dipper spacecraft within the schedule and budget constraints of NASA's MIDEX program was submitted to NASA in 1998. This presentation summarizes the main features of the mission.

Pfaff, R. F., Jr.↗

X-33 Hypersonic Aerodynamic Characteristics

Lockheed Martin Skunk Works, under a cooperative agreement with NASA, will design, build, and fly the X-33, a half-scale prototype of a rocket-based, single-stage-to-orbit (SSTO), reusable launch vehicle (RLV). A 0.007-scale model of the X-33 604BOO02G configuration was tested in four hypersonic facilities at the NASA Langley Research Center to examine vehicle stability and control characteristics and to populate the aerodynamic flight database for the hypersonic regime. The vehicle was found to be longitudinally controllable with less than half of the total body flap deflection capability across the angle of attack range at both Mach 6 and Mach 10. Al these Mach numbers, the vehicle also was shown to be longitudinally stable or neutrally stable for typical (greater than 20 degrees) hypersonic flight attitudes. This configuration was directionally unstable and the use of reaction control jets (RCS) will be necessary to control the vehicle at high angles of attack in the hypersonic flight regime. Mach number and real gas effects on longitudinal aerodynamics were shown to be small relative to X-33 control authority.

Murphy, Kelly J.↗