WorldWideScience

Sample records for spacecraft preferred design

  1. Mechanical Design of Spacecraft

    Science.gov (United States)

    1962-01-01

    In the spring of 1962, engineers from the Engineering Mechanics Division of the Jet Propulsion Laboratory gave a series of lectures on spacecraft design at the Engineering Design seminars conducted at the California Institute of Technology. Several of these lectures were subsequently given at Stanford University as part of the Space Technology seminar series sponsored by the Department of Aeronautics and Astronautics. Presented here are notes taken from these lectures. The lectures were conceived with the intent of providing the audience with a glimpse of the activities of a few mechanical engineers who are involved in designing, building, and testing spacecraft. Engineering courses generally consist of heavily idealized problems in order to allow the more efficient teaching of mathematical technique. Students, therefore, receive a somewhat limited exposure to actual engineering problems, which are typified by more unknowns than equations. For this reason it was considered valuable to demonstrate some of the problems faced by spacecraft designers, the processes used to arrive at solutions, and the interactions between the engineer and the remainder of the organization in which he is constrained to operate. These lecture notes are not so much a compilation of sophisticated techniques of analysis as they are a collection of examples of spacecraft hardware and associated problems. They will be of interest not so much to the experienced spacecraft designer as to those who wonder what part the mechanical engineer plays in an effort such as the exploration of space.

  2. Spacecraft Design Thermal Control Subsystem

    Science.gov (United States)

    Miyake, Robert N.

    2008-01-01

    The Thermal Control Subsystem engineers task is to maintain the temperature of all spacecraft components, subsystems, and the total flight system within specified limits for all flight modes from launch to end-of-mission. In some cases, specific stability and gradient temperature limits will be imposed on flight system elements. The Thermal Control Subsystem of "normal" flight systems, the mass, power, control, and sensing systems mass and power requirements are below 10% of the total flight system resources. In general the thermal control subsystem engineer is involved in all other flight subsystem designs.

  3. Spacecraft early design validation using formal methods

    International Nuclear Information System (INIS)

    Bozzano, Marco; Cimatti, Alessandro; Katoen, Joost-Pieter; Katsaros, Panagiotis; Mokos, Konstantinos; Nguyen, Viet Yen; Noll, Thomas; Postma, Bart; Roveri, Marco

    2014-01-01

    The size and complexity of software in spacecraft is increasing exponentially, and this trend complicates its validation within the context of the overall spacecraft system. Current validation methods are labor-intensive as they rely on manual analysis, review and inspection. For future space missions, we developed – with challenging requirements from the European space industry – a novel modeling language and toolset for a (semi-)automated validation approach. Our modeling language is a dialect of AADL and enables engineers to express the system, the software, and their reliability aspects. The COMPASS toolset utilizes state-of-the-art model checking techniques, both qualitative and probabilistic, for the analysis of requirements related to functional correctness, safety, dependability and performance. Several pilot projects have been performed by industry, with two of them having focused on the system-level of a satellite platform in development. Our efforts resulted in a significant advancement of validating spacecraft designs from several perspectives, using a single integrated system model. The associated technology readiness level increased from level 1 (basic concepts and ideas) to early level 4 (laboratory-tested)

  4. Spacecraft design project: Low Earth orbit communications satellite

    Science.gov (United States)

    Moroney, Dave; Lashbrook, Dave; Mckibben, Barry; Gardener, Nigel; Rivers, Thane; Nottingham, Greg; Golden, Bill; Barfield, Bill; Bruening, Joe; Wood, Dave

    1991-01-01

    This is the final product of the spacecraft design project completed to fulfill the academic requirements of the Spacecraft Design and Integration 2 course (AE-4871) taught at the U.S. Naval Postgraduate School. The Spacecraft Design and Integration 2 course is intended to provide students detailed design experience in selection and design of both satellite system and subsystem components, and their location and integration into a final spacecraft configuration. The design team pursued a design to support a Low Earth Orbiting (LEO) communications system (GLOBALSTAR) currently under development by the Loral Cellular Systems Corporation. Each of the 14 team members was assigned both primary and secondary duties in program management or system design. Hardware selection, spacecraft component design, analysis, and integration were accomplished within the constraints imposed by the 11 week academic schedule and the available design facilities.

  5. Preliminary thermal design of the COLD-SAT spacecraft

    Science.gov (United States)

    Arif, Hugh

    1991-01-01

    The COLD-SAT free-flying spacecraft was to perform experiments with LH2 in the cryogenic fluid management technologies of storage, supply and transfer in reduced gravity. The Phase A preliminary design of the Thermal Control Subsystem (TCS) for the spacecraft exterior and interior surfaces and components of the bus subsystems is described. The TCS was composed of passive elements which were augmented with heaters. Trade studies to minimize the parasitic heat leakage into the cryogen storage tanks are described. Selection procedure for the thermally optimum on-orbit spacecraft attitude was defined. TRASYS-2 and SINDA'85 verification analysis was performed on the design and the results are presented.

  6. Overview of SDCM - The Spacecraft Design and Cost Model

    Science.gov (United States)

    Ferebee, Melvin J.; Farmer, Jeffery T.; Andersen, Gregory C.; Flamm, Jeffery D.; Badi, Deborah M.

    1988-01-01

    The Spacecraft Design and Cost Model (SDCM) is a computer-aided design and analysis tool for synthesizing spacecraft configurations, integrating their subsystems, and generating information concerning on-orbit servicing and costs. SDCM uses a bottom-up method in which the cost and performance parameters for subsystem components are first calculated; the model then sums the contributions from individual components in order to obtain an estimate of sizes and costs for each candidate configuration within a selected spacecraft system. An optimum spacraft configuration can then be selected.

  7. Vibration Antiresonance Design for a Spacecraft Multifunctional Structure

    OpenAIRE

    Li, Dong-Xu; Liu, Wang; Hao, Dong

    2017-01-01

    Spacecraft must withstand rigorous mechanical environment experiences such as acceleration, noise, vibration, and shock during the process of launching, satellite-vehicle separation, and so on. In this paper, a new spacecraft multifunctional structure concept designed by us is introduced. The multifunctional structure has the functions of not only load bearing, but also vibration reduction, energy source, thermal control, and so on, and we adopt a series of viscoelastic parts as connections b...

  8. Maintainability design criteria for packaging of spacecraft replaceable electronic equipment.

    Science.gov (United States)

    Kappler, J. R.; Folsom, A. B.

    1972-01-01

    Maintainability must be designed into long-duration spacecraft and equipment to provide the required high probability of mission success with the least cost and weight. The ability to perform repairs quickly and easily in a space environment can be achieved by imposing specific maintainability design criteria on spacecraft equipment design and installation. A study was funded to investigate and define design criteria for electronic equipment that would permit rapid removal and replacement in a space environment. The results of the study are discussed together with subsequent simulated zero-g demonstration tests of a mockup with new concepts for packaging.

  9. Nuclear-powered Hysat spacecraft: comparative design study

    International Nuclear Information System (INIS)

    Raab, B.

    1975-08-01

    The study shows that the all-nuclear spacecraft can have a substantial weight advantage over a hybrid (nuclear/solar) or all-solar spacecraft, owing to a further reduction in power requirement, and to the elimination of such equipment as the sensor gimbal and rotating joint assemblies. Because the need for a sun-oriented section is eliminated, the all-nuclear spacecraft can be designed as a monolithic structure, with the sensor and other payload firmly secured in a fixed position on the structure. This enhances attitude stability while minimizing structural weight and eliminating the need for flexible fluid lines. Sensor motion can be produced, varied, and controlled within the limits specified by the study contractors by moving the entire spacecraft in the prescribed pattern. A simple attitude control system using available hardware suffices to meet all requirements

  10. Nuclear-Powered GPS Spacecraft Design Study

    Energy Technology Data Exchange (ETDEWEB)

    Raab, Bernard

    1977-05-01

    This is the final report of a study to investigate the potential benefits of a nuclear (radioisotope) - powered satellite for advanced phases of the Global Positioning System (GPS) program. The critical parameters were: power to user; mean mission duration; orbital predictability; thermal control of on-board frequency standards; and vulnerability. The reference design approach is described, and input data are given for two power systems that are under development: an organic Rankine system and a Brayton cycle system. Reference design details are provided and structural design and analysis are discussed, as well as thermal design and analysis. A higher altitude version is also considered.

  11. Simulation and Spacecraft Design: Engineering Mars Landings.

    Science.gov (United States)

    Conway, Erik M

    2015-10-01

    A key issue in history of technology that has received little attention is the use of simulation in engineering design. This article explores the use of both mechanical and numerical simulation in the design of the Mars atmospheric entry phases of the Viking and Mars Pathfinder missions to argue that engineers used both kinds of simulation to develop knowledge of their designs' likely behavior in the poorly known environment of Mars. Each kind of simulation could be used as a warrant of the other's fidelity, in an iterative process of knowledge construction.

  12. Multiple spacecraft configuration designs for coordinated flight missions

    Science.gov (United States)

    Fumenti, Federico; Theil, Stephan

    2018-06-01

    Coordinated flight allows the replacement of a single monolithic spacecraft with multiple smaller ones, based on the principle of distributed systems. According to the mission objectives and to ensure a safe relative motion, constraints on the relative distances need to be satisfied. Initially, differential perturbations are limited by proper orbit design. Then, the induced differential drifts can be properly handled through corrective maneuvers. In this work, several designs are surveyed, defining the initial configuration of a group of spacecraft while counteracting the differential perturbations. For each of the investigated designs, focus is placed upon the number of deployable spacecraft and on the possibility to ensure safe relative motion through station keeping of the initial configuration, with particular attention to the required Δ V budget and the constraints violations.

  13. Spacecraft System Integration and Test: SSTI Lewis critical design audit

    Science.gov (United States)

    Brooks, R. P.; Cha, K. K.

    1995-01-01

    The Critical Design Audit package is the final detailed design package which provides a comprehensive description of the SSTI mission. This package includes the program overview, the system requirements, the science and applications activities, the ground segment development, the assembly, integration and test description, the payload and technology demonstrations, and the spacecraft bus subsystems. Publication and presentation of this document marks the final requirements and design freeze for SSTI.

  14. Preferred design of transfer points

    Energy Technology Data Exchange (ETDEWEB)

    Firstbrook, J

    1983-06-01

    The paper reports the results of a study carried out at MRDE on the performance of transfer points. These sites still require a considerable deployment of manpower. The investigations were divided into 3 main sections: mineral handling; chute design; belt cleaning and spillage conveying. In order to achieve a sufficient level of reliability of a transfer system, it is considered that the coal size should not be greater than 250 mm. Different designs of gravity transfer chute were studied and 3 basic designs emerged as being effective : dump chute, curved site entry, and asymmetric side entry. Selection is dependent on conveyor sizes, speeds, and mineral throughput. Individual belt cleaners are not sufficient to clean belts carrying typical run-of-mine material: two cleaners followed by a set of squeeze rollers are recommended. Several designs of spillage conveyor were investigated; at the present time the electro/hydraulic type appears to be the most satisfactory.

  15. Propulsion Trade Studies for Spacecraft Swarm Mission Design

    Science.gov (United States)

    Dono, Andres; Plice, Laura; Mueting, Joel; Conn, Tracie; Ho, Michael

    2018-01-01

    Spacecraft swarms constitute a challenge from an orbital mechanics standpoint. Traditional mission design involves the application of methodical processes where predefined maneuvers for an individual spacecraft are planned in advance. This approach does not scale to spacecraft swarms consisting of many satellites orbiting in close proximity; non-deterministic maneuvers cannot be preplanned due to the large number of units and the uncertainties associated with their differential deployment and orbital motion. For autonomous small sat swarms in LEO, we investigate two approaches for controlling the relative motion of a swarm. The first method involves modified miniature phasing maneuvers, where maneuvers are prescribed that cancel the differential delta V of each CubeSat's deployment vector. The second method relies on artificial potential functions (APFs) to contain the spacecraft within a volumetric boundary and avoid collisions. Performance results and required delta V budgets are summarized, indicating that each method has advantages and drawbacks for particular applications. The mini phasing maneuvers are more predictable and sustainable. The APF approach provides a more responsive and distributed performance, but at considerable propellant cost. After considering current state of the art CubeSat propulsion systems, we conclude that the first approach is feasible, but the modified APF method of requires too much control authority to be enabled by current propulsion systems.

  16. Leo Spacecraft Charging Design Guidelines: A Proposed NASA Standard

    Science.gov (United States)

    Hillard, G. B.; Ferguson, D. C.

    2004-01-01

    Over the past decade, Low Earth Orbiting (LEO) spacecraft have gradually required ever-increasing power levels. As a rule, this has been accomplished through the use of high voltage systems. Recent failures and anomalies on such spacecraft have been traced to various design practices and materials choices related to the high voltage solar arrays. NASA Glenn has studied these anomalies including plasma chamber testing on arrays similar to those that experienced difficulties on orbit. Many others in the community have been involved in a comprehensive effort to understand the problems and to develop practices to avoid them. The NASA Space Environments and Effects program, recognizing the timeliness of this effort, commissioned and funded a design guidelines document intended to capture the current state of understanding. This document, which was completed in the spring of 2003, has been submitted as a proposed NASA standard. We present here an overview of this document and discuss the effort to develop it as a NASA standard.

  17. Vibration Antiresonance Design for a Spacecraft Multifunctional Structure

    Directory of Open Access Journals (Sweden)

    Dong-Xu Li

    2017-01-01

    Full Text Available Spacecraft must withstand rigorous mechanical environment experiences such as acceleration, noise, vibration, and shock during the process of launching, satellite-vehicle separation, and so on. In this paper, a new spacecraft multifunctional structure concept designed by us is introduced. The multifunctional structure has the functions of not only load bearing, but also vibration reduction, energy source, thermal control, and so on, and we adopt a series of viscoelastic parts as connections between substructures. Especially in this paper, a vibration antiresonance design method is proposed to realize the vibration reduction. The complex zero-point equations of the vibration system are firstly established, and then the vibration antiresonance design for the system is achieved. For solving the difficulties due to viscoelastic characteristics of the connecting parts, we present the determining formulas to obtain the structural parameters, so that the complex zero-point equations can be satisfied. Numerical simulation and ground experiment demonstrate the correctness and effectiveness of the proposed method. This method can solve the structural vibration control problem under the function constraints of load bearing and energy supplying and will expand the performance of spacecraft functional modules.

  18. Application of Modern Fortran to Spacecraft Trajectory Design and Optimization

    Science.gov (United States)

    Williams, Jacob; Falck, Robert D.; Beekman, Izaak B.

    2018-01-01

    In this paper, applications of the modern Fortran programming language to the field of spacecraft trajectory optimization and design are examined. Modern object-oriented Fortran has many advantages for scientific programming, although many legacy Fortran aerospace codes have not been upgraded to use the newer standards (or have been rewritten in other languages perceived to be more modern). NASA's Copernicus spacecraft trajectory optimization program, originally a combination of Fortran 77 and Fortran 95, has attempted to keep up with modern standards and makes significant use of the new language features. Various algorithms and methods are presented from trajectory tools such as Copernicus, as well as modern Fortran open source libraries and other projects.

  19. Preferences and design in insurance and pensions

    DEFF Research Database (Denmark)

    Bruhn, Kenneth

    is on the relation between household preferences and the related optimal product design. Optimal decisions of a household are considered in continuous-time stochastic control theory models. Within a standard expected utility framework we investigate the eects of dierences between household members as well as tax......Life insurance and pension decisions are of the more important fnancial settlements to be decided in a household. In this thesis we investigate dfferent aspects of relevance for decision making within a household, especially focusing on life insurance and pension decisions. The focus......-effects. The focus is on the consumption, investment and life insurance demands. In another modeling framework, we modify the utility measurement and propose a combination of forward and backward looking preferences. At last, a model with very explicit preferences for stability in consumption is investigated and we...

  20. Galileo spacecraft inertial sensors in-flight calibration design

    Science.gov (United States)

    Jahanshahi, M. H.; Lai, J. Y.

    1983-01-01

    The successful navigation of Galileo depends on accurate trajectory correction maneuvers (TCM's) performed during the mission. A set of Inertial Sensor (INS) units, comprised of gyros and accelerometers, mounted on the spacecraft, are utilized to control and monitor the performance of the TCM's. To provide the optimum performance, in-flight calibrations of INS are planned. These calibrations will take place on a regular basis. In this paper, a mathematical description is given of the data reduction technique used in analyzing a typical set of calibration data. The design of the calibration and the inertial sensor error models, necessary for the above analysis, are delineated in detail.

  1. Multi-objective engineering design using preferences

    Science.gov (United States)

    Sanchis, J.; Martinez, M.; Blasco, X.

    2008-03-01

    System design is a complex task when design parameters have to satisy a number of specifications and objectives which often conflict with those of others. This challenging problem is called multi-objective optimization (MOO). The most common approximation consists in optimizing a single cost index with a weighted sum of objectives. However, once weights are chosen the solution does not guarantee the best compromise among specifications, because there is an infinite number of solutions. A new approach can be stated, based on the designer's experience regarding the required specifications and the associated problems. This valuable information can be translated into preferences for design objectives, and will lead the search process to the best solution in terms of these preferences. This article presents a new method, which enumerates these a priori objective preferences. As a result, a single objective is built automatically and no weight selection need be performed. Problems occuring because of the multimodal nature of the generated single cost index are managed with genetic algorithms (GAs).

  2. Thermal design of spacecraft solar arrays using a polyimide foam

    International Nuclear Information System (INIS)

    Bianco, N; Iasiello, M; Naso, V

    2015-01-01

    The design of the Thermal Control System (TCS) of spacecraft solar arrays plays a fundamental role. Indeed, the spacecraft components must operate within a certain range of temperature. If this doesn't occur, their performance is reduced and they may even break. Solar arrays, which are employed to recharge batteries, are directly exposed to the solar heat flux, and they need to be insulated from the earth's surface irradiation. Insulation is currently provided either with a white paint coating or with a Multi Layer Insulation (MLI) system [1]. A configuration based on an open-cell polyimide foam has also been recently proposed [2]. Using polyimide foams in TCSs looks very attractive in terms of costs, weight and assembling. An innovative thermal analysis of the above cited TCS configurations is carried out in this paper, by solving the porous media energy equation, under the assumption of Local Thermal Equilibrium (LTE) between the two phases. Radiation effects through the solar array are also considered by using the Rosseland approximation. Under a stationary daylight condition, temperature profiles are obtained by means of the finite-element based code COMSOL Multiphysics ® . Finally, since the weight plays an important role in aerospace applications, weights of the three TCS configurations are compared. (paper)

  3. Thermal design of spacecraft solar arrays using a polyimide foam

    Science.gov (United States)

    Bianco, N.; Iasiello, M.; Naso, V.

    2015-11-01

    The design of the Thermal Control System (TCS) of spacecraft solar arrays plays a fundamental role. Indeed, the spacecraft components must operate within a certain range of temperature. If this doesn't occur, their performance is reduced and they may even break. Solar arrays, which are employed to recharge batteries, are directly exposed to the solar heat flux, and they need to be insulated from the earth's surface irradiation. Insulation is currently provided either with a white paint coating or with a Multi Layer Insulation (MLI) system [1]. A configuration based on an open-cell polyimide foam has also been recently proposed [2]. Using polyimide foams in TCSs looks very attractive in terms of costs, weight and assembling. An innovative thermal analysis of the above cited TCS configurations is carried out in this paper, by solving the porous media energy equation, under the assumption of Local Thermal Equilibrium (LTE) between the two phases. Radiation effects through the solar array are also considered by using the Rosseland approximation. Under a stationary daylight condition, temperature profiles are obtained by means of the finite-element based code COMSOL Multiphysics®. Finally, since the weight plays an important role in aerospace applications, weights of the three TCS configurations are compared.

  4. Decision-Based Design Integrating Consumer Preferences into Engineering Design

    CERN Document Server

    Chen, Wei; Wassenaar, Henk Jan

    2013-01-01

    Building upon the fundamental principles of decision theory, Decision-Based Design: Integrating Consumer Preferences into Engineering Design presents an analytical approach to enterprise-driven Decision-Based Design (DBD) as a rigorous framework for decision making in engineering design.  Once the related fundamentals of decision theory, economic analysis, and econometrics modelling are established, the remaining chapters describe the entire process, the associated analytical techniques, and the design case studies for integrating consumer preference modeling into the enterprise-driven DBD framework. Methods for identifying key attributes, optimal design of human appraisal experiments, data collection, data analysis, and demand model estimation are presented and illustrated using engineering design case studies. The scope of the chapters also provides: •A rigorous framework of integrating the interests from both producer and consumers in engineering design, •Analytical techniques of consumer choice model...

  5. Spacecraft Conceptual Design Compared to the Apollo Lunar Lander

    Science.gov (United States)

    Young, C.; Bowie, J.; Rust, R.; Lenius, J.; Anderson, M.; Connolly, J.

    2011-01-01

    Future human exploration of the Moon will require an optimized spacecraft design with each sub-system achieving the required minimum capability and maintaining high reliability. The objective of this study was to trade capability with reliability and minimize mass for the lunar lander spacecraft. The NASA parametric concept for a 3-person vehicle to the lunar surface with a 30% mass margin totaled was considerably heavier than the Apollo 15 Lunar Module "as flown" mass of 16.4 metric tons. The additional mass was attributed to mission requirements and system design choices that were made to meet the realities of modern spaceflight. The parametric tool used to size the current concept, Envision, accounts for primary and secondary mass requirements. For example, adding an astronaut increases the mass requirements for suits, water, food, oxygen, as well as, the increase in volume. The environmental control sub-systems becomes heavier with the increased requirements and more structure was needed to support the additional mass. There was also an increase in propellant usage. For comparison, an "Apollo-like" vehicle was created by removing these additional requirements. Utilizing the Envision parametric mass calculation tool and a quantitative reliability estimation tool designed by Valador Inc., it was determined that with today?s current technology a Lunar Module (LM) with Apollo capability could be built with less mass and similar reliability. The reliability of this new lander was compared to Apollo Lunar Module utilizing the same methodology, adjusting for mission timeline changes as well as component differences. Interestingly, the parametric concept's overall estimated risk for loss of mission (LOM) and loss of crew (LOC) did not significantly improve when compared to Apollo.

  6. Interactive Spacecraft Trajectory Design Strategies Featuring Poincare Map Topology

    Science.gov (United States)

    Schlei, Wayne R.

    Space exploration efforts are shifting towards inexpensive and more agile vehicles. Versatility regarding spacecraft trajectories refers to the agility to correct deviations from an intended path or even the ability to adapt the future path to a new destination--all with limited spaceflight resources (i.e., small DeltaV budgets). Trajectory design methods for such nimble vehicles incorporate equally versatile procedures that allow for rapid and interactive decision making while attempting to reduce Delta V budgets, leading to a versatile trajectory design platform. A versatile design paradigm requires the exploitation of Poincare map topology , or the interconnected web of dynamical structures, existing within the chaotic dynamics of multi-body gravitational models to outline low-Delta V transfer options residing nearby to a current path. This investigation details an autonomous procedure to extract the periodic orbits (topology nodes) and correlated asymptotic flow structures (or the invariant manifolds representing topology links). The autonomous process summarized in this investigation (termed PMATE) overcomes discontinuities on the Poincare section that arise in the applied multi-body model (the planar circular restricted three-body problem) and detects a wide variety of novel periodic orbits. New interactive capabilities deliver a visual analytics foundation for versatile spaceflight design, especially for initial guess generation and manipulation. Such interactive strategies include the selection of states and arcs from Poincare section visualizations and the capabilities to draw and drag trajectories to remove dependency on initial state input. Furthermore, immersive selection is expanded to cull invariant manifold structures, yielding low-DeltaV or even DeltaV-free transfers between periodic orbits. The application of interactive design strategies featuring a dense extraction of Poincare map topology is demonstrated for agile spaceflight with a simple

  7. Application of advanced electronics to a future spacecraft computer design

    Science.gov (United States)

    Carney, P. C.

    1980-01-01

    Advancements in hardware and software technology are summarized with specific emphasis on spacecraft computer capabilities. Available state of the art technology is reviewed and candidate architectures are defined.

  8. Radioisotope AMTEC power system designs for spacecraft applications

    International Nuclear Information System (INIS)

    Ivanenok, J.F. III; Sievers, R.K.; Hunt, T.K.; Johnson, G.A.

    1993-01-01

    The Alkali Metal Thermal to Electric Converter (AMTEC) system is an exceptional candidate for high performance spacecraft power systems including small systems powered by General Purpose Heat Sources (GPHS). The AMTEC converter is best described as a thermally regenerative electrochemical concentration cell. AMTEC is a static energy conversion device and can operate at efficiencies between 15% and 30%. The single tube, remote condensed, wick return minicell design has been incorporated into a radioisotope powered system model. Reported cell efficiencies used for these system design studies ranged from 15% to 25%. This efficiency is significantly higher than other static conversion systems operating at the same temperatures. Savings in mass and cost, relative to other more conventional static conversion systems, have also been shown. The minicell used for this system study has many advanced features not combined in previous designs, including wick return, remote condensing, and hot zone feedthroughs. All of these features significantly enhance the performance of the AMTEC cell. Additionally, the cell end provides enough area for adequate heat transfer from the GPHS module, eliminating the need for a ''hot shoe'', and reducing the complexity and weight of the system. This paper describes and compares small (two module) and larger (16 module) AMTEC radioisotope powered systems and describes the computer model developed to predict their performance

  9. Design feasibility via ascent optimality for next-generation spacecraft

    Science.gov (United States)

    Miele, A.; Mancuso, S.

    This paper deals with the optimization of the ascent trajectories for single-stage-sub-orbit (SSSO), single-stage-to-orbit (SSTO), and two-stage-to-orbit (TSTO) rocket-powered spacecraft. The maximum payload weight problem is studied for different values of the engine specific impulse and spacecraft structural factor. The main conclusions are that: feasibility of SSSO spacecraft is guaranteed for all the parameter combinations considered; feasibility of SSTO spacecraft depends strongly on the parameter combination chosen; not only feasibility of TSTO spacecraft is guaranteed for all the parameter combinations considered, but the TSTO payload is several times the SSTO payload. Improvements in engine specific impulse and spacecraft structural factor are desirable and crucial for SSTO feasibility; indeed, aerodynamic improvements do not yield significant improvements in payload. For SSSO, SSTO, and TSTO spacecraft, simple engineering approximations are developed connecting the maximum payload weight to the engine specific impulse and spacecraft structural factor. With reference to the specific impulse/structural factor domain, these engineering approximations lead to the construction of zero-payload lines separating the feasibility region (positive payload) from the unfeasibility region (negative payload).

  10. Spacecraft Conceptual Design for the 8-Meter Advanced Technology Large Aperture Space Telescope (ATLAST)

    Science.gov (United States)

    Hopkins, Randall C.; Capizzo, Peter; Fincher, Sharon; Hornsby, Linda S.; Jones, David

    2010-01-01

    The Advanced Concepts Office at Marshall Space Flight Center completed a brief spacecraft design study for the 8-meter monolithic Advanced Technology Large Aperture Space Telescope (ATLAST-8m). This spacecraft concept provides all power, communication, telemetry, avionics, guidance and control, and thermal control for the observatory, and inserts the observatory into a halo orbit about the second Sun-Earth Lagrange point. The multidisciplinary design team created a simple spacecraft design that enables component and science instrument servicing, employs articulating solar panels for help with momentum management, and provides precise pointing control while at the same time fast slewing for the observatory.

  11. Multi-objective optimisation for spacecraft design for demise and survivability

    OpenAIRE

    Trisolini, Mirko; Colombo, Camilla; Lewis, Hugh

    2017-01-01

    The paper presents the development of a multi-objective optimisation framework to study the effects that preliminary design choices have on the demisability and the survivability of a spacecraft. Building a spacecraft such that most of it will demise during the re-entry through design-for-demise strategies may lead to design that are more vulnerable to space debris impacts, thus compromising the reliability of the mission. The two models developed to analyse the demisability and the survivabi...

  12. Application of software technology to a future spacecraft computer design

    Science.gov (United States)

    Labaugh, R. J.

    1980-01-01

    A study was conducted to determine how major improvements in spacecraft computer systems can be obtained from recent advances in hardware and software technology. Investigations into integrated circuit technology indicated that the CMOS/SOS chip set being developed for the Air Force Avionics Laboratory at Wright Patterson had the best potential for improving the performance of spaceborne computer systems. An integral part of the chip set is the bit slice arithmetic and logic unit. The flexibility allowed by microprogramming, combined with the software investigations, led to the specification of a baseline architecture and instruction set.

  13. Conceptual Design of an Electric Sail Technology Demonstration Mission Spacecraft

    Science.gov (United States)

    Wiegmann, Bruce M.

    2017-01-01

    There is great interest in examining the outer planets of our solar system and Heliopause region (edge of Solar System) and beyond regions of interstellar space by both the Planetary and Heliophysics communities. These needs are well docu-mented in the recent National Academy of Sciences Decadal Surveys. There is significant interest in developing revolutionary propulsion techniques that will enable such Heliopause scientific missions to be completed within 10 to15 years of the launch date. One such enabling propulsion technique commonly known as Electric Sail (E-Sail) propulsion employs positively charged bare wire tethers that extend radially outward from a rotating spacecraft spinning at a rate of one revolution per hour. Around the positively charged bare-wire tethers, a Debye Sheath is created once positive voltage is applied. This sheath stands off of the bare wire tether at a sheath diameter that is proportional to the voltage in the wire coupled with the flux density of solar wind ions within the solar system (or the location of spacecraft in the solar system. The protons that are expended from the sun (solar wind) at 400 to 800 km/sec are electrostatically repelled away from these positively charged Debye sheaths and propulsive thrust is produced via the resulting momentum transfer. The amount of thrust produced is directly proportional to the total wire length. The Marshall Space Flight Center (MSFC) Electric Sail team is currently funded via a two year Phase II NASA Innovative Advanced Concepts (NIAC) awarded in July 2015. The team's current activities are: 1) Developing a Particle in Cell (PIC) numeric engineering model from the experimental data collected at MSFC's Solar Wind Facility on the interaction between simulated solar wind interaction with a charged bare wire that can be applied to a variety of missions, 2) The development of the necessary tether deployers and tethers to enable successful de-ployment of multiple, multi km length bare tethers

  14. Weight estimates and packaging techniques for the microwave radiometer spacecraft. [shuttle compatible design

    Science.gov (United States)

    Jensen, J. K.; Wright, R. L.

    1981-01-01

    Estimates of total spacecraft weight and packaging options were made for three conceptual designs of a microwave radiometer spacecraft. Erectable structures were found to be slightly lighter than deployable structures but could be packaged in one-tenth the volume. The tension rim concept, an unconventional design approach, was found to be the lightest and transportable to orbit in the least number of shuttle flights.

  15. The mechanical design and dynamic testing of the IBEX-H1 electrostatic analyzer spacecraft instrument

    Energy Technology Data Exchange (ETDEWEB)

    Bernardin, John D [Los Alamos National Laboratory; Baca, Allen G [SNL

    2009-01-01

    This paper presents the mechanical design, fabrication and dynamic testing of an electrostatic analyzer spacecraft instrument. The functional and environmental requirements combined with limited spacecraft accommodations, resulted in complex component geometries, unique material selections, and difficult fabrication processes. The challenging aspects of the mechanical design and several of the more difficult production processes are discussed. In addition, the successes, failures, and lessons learned from acoustic and random vibration testing of a full-scale prototype instrument are presented.

  16. Preference-Based Design in Architecture

    NARCIS (Netherlands)

    Binnekamp, R.

    2010-01-01

    Architectural design is a complex process as a result of two prominent characteristics of choice making: 1) multiple designs can fit into one intended purpose, which raises the question: how to choose the design that fits best, and 2) a multitude of decision makers have an interest in the design

  17. Design of Launcher Towards Spacecraft Comfort: Ariane 6 Objectives

    Science.gov (United States)

    Mourey, Patrick; Lambare, Hadrien; Valbuena, Matias F.

    2014-06-01

    Preliminary advanced studies were performed recently to select the possible concepts for a launcher that could succeed to Ariane 5. During the end of 2012 Space Ministry Conference, a configuration defining the propellant of the stages and the coarse staging ("PPH") was frozen in order to engage the preliminary selection concept studies. The first phase consisted to select the main features of the architecture in order to go deeper in the different matters or the advanced studies. The concept was selected mid of 2013.During all these phases of the preliminary project, different criteria (such as the recurring cost which is a major one) were used to quote the different concepts, among which the "payload comfort", ie the minimization of the environment generated by the launcher toward the satellites.The minimization of the environment was first expressed in term of objectives in the Mission Requirement Document (MRD) for the different mechanical environment such as quasi-static loads, dynamic loads, acoustics, shocks... Criteria such as usable volume, satellites frequency requirement and interface requirement are also expressed in the MRD.The definition of these different criteria was of course fixed taking benefit from the launcher operator experience based on a long story of dealing with spacecraft-launcher interface issues on Ariane, Soyouz and Vega. The general idea is to target improved or similar levels than those currently applicable for Ariane 5. For some environment for which a special need is anticipated from the potential end users, a special effort is aimed.The preliminary advanced study phase is currently running and has to address specific topics such as the definition of the upper part layout including geometry ofthe fairing, the definition of the launch pad with preliminary ideas to minimize acoustics and blast wave or first calculations on dimensioning dynamic load- cases such as thrust oscillations of the solid rocket motors (SRM).The present paper

  18. A design for a reusable water-based spacecraft known as the spacecoach

    CERN Document Server

    McConnell, Brian

    2016-01-01

     Based on components already in existence, this manual details a reference design for an interplanetary spacecraft that is simple, durable, fully reusable and comprised mostly of water. Using such an accessible material leads to a spacecraft architecture that is radically simpler, safer and cheaper than conventional capsule based designs. If developed, the potential affordability of the design will substantially open all of the inner solar system to human exploration. A spacecraft that is comprised mostly of water will be much more like a living cell or a terrarium than a conventional rocket and capsule design. It will use water for many purposes before it is superheated in electric engines for propulsion, purposes which include radiation shielding, heat management, basic life support, crew consumption and comfort. The authors coined the term "spacecoaches" to describe them, as an allusion to the Prairie Schooners of the Old West, which were simple, rugged, and could live off the land.

  19. Contingency Trajectory Design for a Lunar Orbit Insertion Maneuver Failure by the LADEE Spacecraft

    Science.gov (United States)

    Genova, A. L.

    2014-01-01

    This paper presents results from a contingency trajectory analysis performed for the Lunar Atmosphere & Dust Environment Explorer (LADEE) mission in the event of a missed lunar-orbit insertion (LOI) maneuver by the LADEE spacecraft. The effects of varying solar perturbations in the vicinity of the weak stability boundary (WSB) in the Sun-Earth system on the trajectory design are analyzed and discussed. It is shown that geocentric recovery trajectory options existed for the LADEE spacecraft, depending on the spacecraft's recovery time to perform an Earth escape-prevention maneuver after the hypothetical LOI maneuver failure and subsequent path traveled through the Sun-Earth WSB. If Earth-escape occurred, a heliocentric recovery option existed, but with reduced science capacapability for the spacecraft in an eccentric, not circular near-equatorial retrograde lunar orbit.

  20. Electrical design for origami solar panels and a small spacecraft test mission

    Science.gov (United States)

    Drewelow, James; Straub, Jeremy

    2017-05-01

    Efficient power generation is crucial to the design of spacecraft. Mass, volume, and other limitations prevent the use of traditional spacecraft support structures from being suitable for the size of solar array required for some missions. Folding solar panel / panel array systems, however, present a number of design challenges. This paper considers the electrical design of an origami system. Specifically, it considers how to provide low impedance, durable channels for the generated power and the electrical aspects of the deployment system and procedure. The ability to dynamically reconfigure the electrical configuration of the solar cells is also discussed. Finally, a small satellite test mission to demonstrate the technology is proposed, before concluding.

  1. Design and analysis study of a spacecraft optical transceiver package

    Science.gov (United States)

    Lambert, S. G.

    1985-01-01

    A detailed system level design of an Optical Transceiver Package (OPTRANSPAC) for a deep space vehicle whose mission is outer planet exploration is developed. In addition to the terminal design, this study provides estimates of the dynamic environments to be encountered by the transceiver throughout its mission life. Optical communication link analysis, optical thin lens design, electronic functional design and mechanical layout and packaging are employed in the terminal design. Results of the study describe an Optical Transceiver Package capable of communicating to an Earth Orbiting Relay Station at a distance of 10 Astronomical Units (AU) and data rates up to 100 KBPS. The transceiver is also capable of receiving 1 KBPS of command data from the Earth Relay. The physical dimensions of the terminal are contained within a 3.5' x 1.5' x 2.0' envelope and the transceiver weight and power are estimated at 52.2 Kg (115 pounds) and 57 watts, respectively.

  2. Centralized database for interconnection system design. [for spacecraft

    Science.gov (United States)

    Billitti, Joseph W.

    1989-01-01

    A database application called DFACS (Database, Forms and Applications for Cabling and Systems) is described. The objective of DFACS is to improve the speed and accuracy of interconnection system information flow during the design and fabrication stages of a project, while simultaneously supporting both the horizontal (end-to-end wiring) and the vertical (wiring by connector) design stratagems used by the Jet Propulsion Laboratory (JPL) project engineering community. The DFACS architecture is centered around a centralized database and program methodology which emulates the manual design process hitherto used at JPL. DFACS has been tested and successfully applied to existing JPL hardware tasks with a resulting reduction in schedule time and costs.

  3. Variation in housing design: identifying customer preferences

    NARCIS (Netherlands)

    Hofman, Erwin; Halman, Johannes I.M.; Ion, Roxana A.

    2006-01-01

    House builders in different countries are exploring ways to deliver higher levels of customisation in housing design. To create such variety at acceptable cost, it is important to know how potential buyers of new houses prioritise the different elements such as bathroom, kitchen and roof type of a

  4. Variation in housing design: identitying customer preferences

    NARCIS (Netherlands)

    Hofman, E.; Halman, J.I.M.; Ion, R.A.

    2006-01-01

    House builders in different countries are exploring ways to deliver higher levels of customisation in housing design. To create such variety at acceptable cost, it is important to know how potential buyers of new houses prioritise the different elements such as bathroom, kitchen and roof type of a

  5. SSTL based thermal and power efficient RAM design on 28nm FPGA for spacecraft

    DEFF Research Database (Denmark)

    Kalia, Kartik; Pandey, Bishwajeet; Hussain, D. M.A.

    2016-01-01

    In this paper, an approach is made to design a Thermal and Power efficient RAM for that reason we have used DDR4L memory and six different members of SSTL I/Os standards on 28nm technology. Every spacecraft requires most energy efficient electronic system and for that very purpose we have designe...

  6. Mapping Design Students' Aesthetic and Visual Preference

    DEFF Research Database (Denmark)

    Raahauge, Kirsten Marie; Ohrt, Ann Merete

    2016-01-01

    2014). The students were asked to create a “Wunderkammer” of personal collected images and things from their local cultural and physical environment. The focus of the workshops is collecting and organizing objects from the studens visual explorations within the following topics: body, home, urban space......, identity, and cultural codes. The workshops are documented, analysed and compared in order to get a better understanding of how, and if, different universities’ learning methods and cultural backgrounds influence the students’ design approaches, practices and conceptions. In this way we hope to broaden...

  7. A simple method to design non-collision relative orbits for close spacecraft formation flying

    Science.gov (United States)

    Jiang, Wei; Li, JunFeng; Jiang, FangHua; Bernelli-Zazzera, Franco

    2018-05-01

    A set of linearized relative motion equations of spacecraft flying on unperturbed elliptical orbits are specialized for particular cases, where the leader orbit is circular or equatorial. Based on these extended equations, we are able to analyze the relative motion regulation between a pair of spacecraft flying on arbitrary unperturbed orbits with the same semi-major axis in close formation. Given the initial orbital elements of the leader, this paper presents a simple way to design initial relative orbital elements of close spacecraft with the same semi-major axis, thus preventing collision under non-perturbed conditions. Considering the mean influence of J 2 perturbation, namely secular J 2 perturbation, we derive the mean derivatives of orbital element differences, and then expand them to first order. Thus the first order expansion of orbital element differences can be added to the relative motion equations for further analysis. For a pair of spacecraft that will never collide under non-perturbed situations, we present a simple method to determine whether a collision will occur when J 2 perturbation is considered. Examples are given to prove the validity of the extended relative motion equations and to illustrate how the methods presented can be used. The simple method for designing initial relative orbital elements proposed here could be helpful to the preliminary design of the relative orbital elements between spacecraft in a close formation, when collision avoidance is necessary.

  8. Flexible Multi-Body Spacecraft Simulator: Design, Construction, and Experiments

    Science.gov (United States)

    2017-12-01

    required analysis. The first step in applying Pontryagin’s Principle is writing the control Hamiltonian: ( , , , ) ( , , ) ( , , )TH x u t F x u t f...of holes allows the adapter plate to be fastened to the MBSS top plate. 26 The base and link are designed to be modular and expandable. The link...https://www.quanser.com/products/2-dof-serial-flexible-joint/ 79 INITIAL DISTRIBUTION LIST 1. Defense Technical Information Center Ft. Belvoir

  9. Reference Design for a Simple, Durable and Refuelable Interplanetary Spacecraft

    Science.gov (United States)

    McConnell, B. S.; Tolley, A. M.

    This article describes a reference design for interplanetary vessels, composed mostly of water, that utilize simplified RF engines for low thrust, long duration propulsion, and hydrogen peroxide for short duration, high thrust burns. The electrothermal engines are designed to heat a wide range of liquid materials, possibly also milled solids or surface dusts. The system emphasizes simple components and processes based on older technologies, many well known since the 1960s, that are understandable, can process a variety of materials, and are easily serviced in flight. The goal is to radically simplify systems and their inter-dependencies, to a point where a reasonably skilled person can learn to operate these vessels, not unlike a sailboat, and to eliminate many design and testing bottlenecks in their construction. The use of water, or hydrogen peroxide generated in situ from that water, is multiply advantageous because it can be used for structure, consumption, irrigation, radiation and debris shielding, and thermal regulation, and thus greatly reduce dead weight by creating an almost fully consumable ship. This also enables the ship to utilize a wide range of in situ materials, and eventually obtain reaction mass from lower gravity sites. The ability to switch between low thrust, constant power and high thrust, short duration maneuvers will enable these ships to travel freely and reach many interesting destinations throughout the solar system. One can think of them as “spacecoaches”, not unlike the prairie schooners of the Old West, which were rugged, serviceable by tradesmen, and easily maintained.

  10. Design preferences and cognitive styles: experimentation by automated website synthesis.

    Science.gov (United States)

    Leung, Siu-Wai; Lee, John; Johnson, Chris; Robertson, David

    2012-06-29

    This article aims to demonstrate computational synthesis of Web-based experiments in undertaking experimentation on relationships among the participants' design preference, rationale, and cognitive test performance. The exemplified experiments were computationally synthesised, including the websites as materials, experiment protocols as methods, and cognitive tests as protocol modules. This work also exemplifies the use of a website synthesiser as an essential instrument enabling the participants to explore different possible designs, which were generated on the fly, before selection of preferred designs. The participants were given interactive tree and table generators so that they could explore some different ways of presenting causality information in tables and trees as the visualisation formats. The participants gave their preference ratings for the available designs, as well as their rationale (criteria) for their design decisions. The participants were also asked to take four cognitive tests, which focus on the aspects of visualisation and analogy-making. The relationships among preference ratings, rationale, and the results of cognitive tests were analysed by conservative non-parametric statistics including Wilcoxon test, Krustal-Wallis test, and Kendall correlation. In the test, 41 of the total 64 participants preferred graphical (tree-form) to tabular presentation. Despite the popular preference for graphical presentation, the given tabular presentation was generally rated to be easier than graphical presentation to interpret, especially by those who were scored lower in the visualization and analogy-making tests. This piece of evidence helps generate a hypothesis that design preferences are related to specific cognitive abilities. Without the use of computational synthesis, the experiment setup and scientific results would be impractical to obtain.

  11. Proposed Modifications to Engineering Design Guidelines Related to Resistivity Measurements and Spacecraft Charging

    Science.gov (United States)

    Dennison, J. R.; Swaminathan, Prasanna; Jost, Randy; Brunson, Jerilyn; Green, Nelson; Frederickson, A. Robb

    2005-01-01

    A key parameter in modeling differential spacecraft charging is the resistivity of insulating materials. This determines how charge will accumulate and redistribute across the spacecraft, as well as the time scale for charge transport and dissipation. Existing spacecraft charging guidelines recommend use of tests and imported resistivity data from handbooks that are based principally upon ASTM methods that are more applicable to classical ground conditions and designed for problems associated with power loss through the dielectric, than for how long charge can be stored on an insulator. These data have been found to underestimate charging effects by one to four orders of magnitude for spacecraft charging applications. A review is presented of methods to measure the resistive of highly insulating materials, including the electrometer-resistance method, the electrometer-constant voltage method, the voltage rate-of-change method and the charge storage method. This is based on joint experimental studies conducted at NASA Jet Propulsion Laboratory and Utah State University to investigate the charge storage method and its relation to spacecraft charging. The different methods are found to be appropriate for different resistivity ranges and for different charging circumstances. A simple physics-based model of these methods allows separation of the polarization current and dark current components from long duration measurements of resistivity over day- to month-long time scales. Model parameters are directly related to the magnitude of charge transfer and storage and the rate of charge transport. The model largely explains the observed differences in resistivity found using the different methods and provides a framework for recommendations for the appropriate test method for spacecraft materials with different resistivities and applications. The proposed changes to the existing engineering guidelines are intended to provide design engineers more appropriate methods for

  12. Consumer preferences in the design of airport passenger areas

    NARCIS (Netherlands)

    Van Oel, C.J.; Van den Berkhof, F.W.

    2013-01-01

    In recent decades, commercial developments have become increasingly important for the overall profit of airports. However, little is known about consumer preferences regarding the design of passenger areas, which is striking as the design of terminal buildings affects consumers' emotional state and

  13. A Psychological Measurement of Student Testing Design Preferences.

    Science.gov (United States)

    Shukla, P. K.; Bruno, James

    An analytical technique from the field of market research called conjoint analysis was applied to a psychological measurement of student testing design preferences. Past concerns with testing design are reviewed, and a newer approach to testing is identified--the modified confidence weighted-admissible probability measurement (MCW-APM) test…

  14. Atmospheric electricity. [lightning protection criteria in spacecraft design

    Science.gov (United States)

    Daniels, G. E.

    1973-01-01

    Atmospheric electricity must be considered in the design, transportation, and operation of aerospace vehicles. The effect of the atmosphere as an insulator and conductor of high voltage electricity, at various atmospheric pressures, must also be considered. The vehicle can be protected as follows: (1) By insuring that all metallic sections are connected by electrical bonding so that the current flow from a lightning stroke is conducted over the skin without any gaps where sparking would occur or current would be carried inside; (2) by protecting buildings and other structures on the ground with a system of lightning rods and wires over the outside to carry the lightning stroke into the ground; (3) by providing a zone of protection for launch complexes; (4) by providing protection devices in critical circuits; (5) by using systems which have no single failure mode; and (6) by appropriate shielding of units sensitive to electromagnetic radiation.

  15. Preferences, behaviour and the design of financial contracts

    DEFF Research Database (Denmark)

    Nordfang, Maj-Britt

    of insurance customers may lower the premiums of the high-risk customers without aecting the premium level of the low-risk customers when a solvency capital requirement is imposed. The papers highlight how the risk preferences of individual consumers relate to the design of nancial contracts and the regulation......Today's insurance and nancial markets are characterized by and ever increasing complexity and product choice. How do we assist individual household consumers in making informed choices about their nancial positions in these markets? This thesis consists of ve separate research papers that are all...... in some way concerned with the design and regulation of nancial contracts in relation to consumer preferences under uncertainty. First, the design of mortgage products in relation to consumer preferences in a market with a stochastic interest rate is examined. We derive the (extreme) characteristics...

  16. JEM-EUSO Design for Accommodation on the SpaceX Dragon Spacecraft

    Science.gov (United States)

    Christl, Mark

    2013-01-01

    The JEM-EUSO mission has been planned for launch on JAXA's H2 Launch Vehicle. Recently, the SpaceX Dragon spacecraft has emerged as an alternative payload carrier for JEM-EUSO. This paper will discuss a concept for the re-design of JEM-EUSO so that it can be launched on Dragon.

  17. System concepts and design examples for optical communication with planetary spacecraft

    Science.gov (United States)

    Lesh, James R.

    Systems concepts for optical communication with future deep-space (planetary) spacecraft are described. These include not only the optical transceiver package aboard the distant spacecraft, but the earth-vicinity optical-communications receiving station as well. Both ground-based, and earth-orbiting receivers are considered. Design examples for a number of proposed or potential deep-space missions are then presented. These include an orbital mission to Saturn, a Lander and Rover mission to Mars, and an astronomical mission to a distance of 1000 astronomical units.

  18. SEQ-POINTER: Next generation, planetary spacecraft remote sensing science observation design tool

    Science.gov (United States)

    Boyer, Jeffrey S.

    1994-11-01

    Since Mariner, NASA-JPL planetary missions have been supported by ground software to plan and design remote sensing science observations. The software used by the science and sequence designers to plan and design observations has evolved with mission and technological advances. The original program, PEGASIS (Mariners 4, 6, and 7), was re-engineered as POGASIS (Mariner 9, Viking, and Mariner 10), and again later as POINTER (Voyager and Galileo). Each of these programs were developed under technological, political, and fiscal constraints which limited their adaptability to other missions and spacecraft designs. Implementation of a multi-mission tool, SEQ POINTER, under the auspices of the JPL Multimission Operations Systems Office (MOSO) is in progress. This version has been designed to address the limitations experienced on previous versions as they were being adapted to a new mission and spacecraft. The tool has been modularly designed with subroutine interface structures to support interchangeable celestial body and spacecraft definition models. The computational and graphics modules have also been designed to interface with data collected from previous spacecraft, or on-going observations, which describe the surface of each target body. These enhancements make SEQ POINTER a candidate for low-cost mission usage, when a remote sensing science observation design capability is required. The current and planned capabilities of the tool will be discussed. The presentation will also include a 5-10 minute video presentation demonstrating the capabilities of a proto-Cassini Project version that was adapted to test the tool. The work described in this abstract was performed by the Jet Propulsion Laboratory, California Institute of Technology, under contract to the National Aeronautics and Space Administration.

  19. Particulate Matter Filtration Design Considerations for Crewed Spacecraft Life Support Systems

    Science.gov (United States)

    Agui, Juan H.; Vijayakumar, R.; Perry, Jay L.

    2016-01-01

    Particulate matter filtration is a key component of crewed spacecraft cabin ventilation and life support system (LSS) architectures. The basic particulate matter filtration functional requirements as they relate to an exploration vehicle LSS architecture are presented. Particulate matter filtration concepts are reviewed and design considerations are discussed. A concept for a particulate matter filtration architecture suitable for exploration missions is presented. The conceptual architecture considers the results from developmental work and incorporates best practice design considerations.

  20. Modeling agent's preferences by its designer's social value orientation

    Science.gov (United States)

    Zuckerman, Inon; Cheng, Kan-Leung; Nau, Dana S.

    2018-03-01

    Human social preferences have been shown to play an important role in many areas of decision-making. There is evidence from the social science literature that human preferences in interpersonal interactions depend partly on a measurable personality trait called, Social Value Orientation (SVO). Automated agents are often written by humans to serve as their delegates when interacting with other agents. Thus, one might expect an agent's behaviour to be influenced by the SVO of its human designer. With that in mind, we present the following: first, we explore, discuss and provide a solution to the question of how SVO tests that were designed for humans can be used to evaluate agents' social preferences. Second, we show that in our example domain there is a medium-high positive correlation between the social preferences of agents and their human designers. Third, we exemplify how the SVO information of the designer can be used to improve the performance of some other agents playing against those agents, and lastly, we develop and exemplify the behavioural signature SVO model which allows us to better predict performances when interactions are repeated and behaviour is adapted.

  1. The Global Precipitation Measurement (GPM) Spacecraft Power System Design and Orbital Performance

    Science.gov (United States)

    Dakermanji, George; Burns, Michael; Lee, Leonine; Lyons, John; Kim, David; Spitzer, Thomas; Kercheval, Bradford

    2016-01-01

    The Global Precipitation Measurement (GPM) spacecraft was jointly developed by National Aeronautics and Space Administration (NASA) and Japan Aerospace Exploration Agency (JAXA). It is a Low Earth Orbit (LEO) spacecraft launched on February 27, 2014. The spacecraft is in a circular 400 Km altitude, 65 degrees inclination nadir pointing orbit with a three year basic mission life. The solar array consists of two sun tracking wings with cable wraps. The panels are populated with triple junction cells of nominal 29.5% efficiency. One axis is canted by 52 degrees to provide power to the spacecraft at high beta angles. The power system is a Direct Energy Transfer (DET) system designed to support 1950 Watts orbit average power. The batteries use SONY 18650HC cells and consist of three 8s x 84p batteries operated in parallel as a single battery. The paper describes the power system design details, its performance to date and the lithium ion battery model that was developed for use in the energy balance analysis and is being used to predict the on-orbit health of the battery.

  2. Beyond Trust: Web Site Design Preferences Across Cultures

    OpenAIRE

    Dianne Cyr; Carole Bonanni; John Bowes; Joe Ilsever

    2005-01-01

    The growth of Internet shopping motivates a better understanding of how e-loyalty is built online between businesses and consumers. In this study, Web site design and culture are advanced as important to Web site trust, Web site satisfaction, and e-loyalty in online business relationships. Based on data collected in Canada, the U.S., Germany, and Japan, the research considers (1) examining within culture preferences for design elements of a local vs. a foreign Web site and subsequent particip...

  3. Estimation Model of Spacecraft Parameters and Cost Based on a Statistical Analysis of COMPASS Designs

    Science.gov (United States)

    Gerberich, Matthew W.; Oleson, Steven R.

    2013-01-01

    The Collaborative Modeling for Parametric Assessment of Space Systems (COMPASS) team at Glenn Research Center has performed integrated system analysis of conceptual spacecraft mission designs since 2006 using a multidisciplinary concurrent engineering process. The set of completed designs was archived in a database, to allow for the study of relationships between design parameters. Although COMPASS uses a parametric spacecraft costing model, this research investigated the possibility of using a top-down approach to rapidly estimate the overall vehicle costs. This paper presents the relationships between significant design variables, including breakdowns of dry mass, wet mass, and cost. It also develops a model for a broad estimate of these parameters through basic mission characteristics, including the target location distance, the payload mass, the duration, the delta-v requirement, and the type of mission, propulsion, and electrical power. Finally, this paper examines the accuracy of this model in regards to past COMPASS designs, with an assessment of outlying spacecraft, and compares the results to historical data of completed NASA missions.

  4. A Quantitative Human Spacecraft Design Evaluation Model for Assessing Crew Accommodation and Utilization

    Science.gov (United States)

    Fanchiang, Christine

    Crew performance, including both accommodation and utilization factors, is an integral part of every human spaceflight mission from commercial space tourism, to the demanding journey to Mars and beyond. Spacecraft were historically built by engineers and technologists trying to adapt the vehicle into cutting edge rocketry with the assumption that the astronauts could be trained and will adapt to the design. By and large, that is still the current state of the art. It is recognized, however, that poor human-machine design integration can lead to catastrophic and deadly mishaps. The premise of this work relies on the idea that if an accurate predictive model exists to forecast crew performance issues as a result of spacecraft design and operations, it can help designers and managers make better decisions throughout the design process, and ensure that the crewmembers are well-integrated with the system from the very start. The result should be a high-quality, user-friendly spacecraft that optimizes the utilization of the crew while keeping them alive, healthy, and happy during the course of the mission. Therefore, the goal of this work was to develop an integrative framework to quantitatively evaluate a spacecraft design from the crew performance perspective. The approach presented here is done at a very fundamental level starting with identifying and defining basic terminology, and then builds up important axioms of human spaceflight that lay the foundation for how such a framework can be developed. With the framework established, a methodology for characterizing the outcome using a mathematical model was developed by pulling from existing metrics and data collected on human performance in space. Representative test scenarios were run to show what information could be garnered and how it could be applied as a useful, understandable metric for future spacecraft design. While the model is the primary tangible product from this research, the more interesting outcome of

  5. Smart home design and operation preferences of Americans and Koreans.

    Science.gov (United States)

    Jeong, Kyeong-Ah; Salvendy, Gavriel; Proctor, Robert W

    2010-05-01

    The purpose of the present study was to generate both culture-specific and universal design and operational guidelines for smart homes. Questionnaire surveys were performed in the USA and South Korea to collect data on preferences for various aspects of the design and operation of smart homes. The factors that the survey participants considered most important were derived through factor analyses of the survey data and the responses of Americans and Koreans were compared to generate culture-specific guidelines. The five factors derived were: 1) environmental connection and control; 2) smart devices (appliances) and their control; 3) physical safety and security concerns; 4) comfort and relaxation issues; 5) control restriction issues. The two cultures showed different preference structures with statistical significance for all five factors. Prediction capability of the derived factors was also examined through multiple regressions for buying intention, interest, self-vision of living, moving intention, living satisfaction and perceived time and effort savings. 'Environmental connection and control' and 'smart devices (appliances) and their control' seemed to be the most influential factors for Americans and Koreans, respectively. STATEMENT OF RELEVANCE: Analysis of a survey of design and operational preferences for smart homes yielded five factors on which US and South Korean respondents differed. These factors form the basis for culture-specific guidelines, which, along with universal guidelines, should be followed in design of user-centred smart homes.

  6. The electrical power subsystem design for the high energy solar physics spacecraft concepts

    Science.gov (United States)

    Kulkarni, Milind

    1993-01-01

    This paper discusses the Electrical Power Subsystem (EPS) requirements, architecture, design description, performance analysis, and heritage of the components for two spacecraft concepts for the High Energy Solar Physics (HESP) Mission. It summarizes the mission requirements and the spacecraft subsystems and instrument power requirements, and it describes the EPS architecture for both options. A trade study performed on the selection of the solar cells - body mounted versus deployed panels - and the optimum number of panels is also presented. Solar cell manufacturing losses, array manufacturing losses, and the radiation and temperature effects on the GaAs/Ge and Si solar cells were considered part of the trade study and are included in this paper. Solar cell characteristics, cell circuit description, and the solar array area design are presented, as is battery sizing analysis performed based on the power requirements during launch and initial spacecraft operations. This paper discusses Earth occultation periods and the battery power requirements during this period as well as shunt control, battery conditioning, and bus regulation schemes. Design margins, redundancy philosophy, and predicted on-orbit battery and solar cell performance are summarized. Finally, the heritage of the components and technology risk assessment are provided.

  7. Contributions of microgravity test results to the design of spacecraft fire-safety systems

    Science.gov (United States)

    Friedman, Robert; Urban, David L.

    1993-01-01

    Experiments conducted in spacecraft and drop towers show that thin-sheet materials have reduced flammability ranges and flame-spread rates under quiescent low-gravity environments (microgravity) compared to normal gravity. Furthermore, low-gravity flames may be suppressed more easily by atmospheric dilution or decreasing atmospheric total pressure than their normal-gravity counterparts. The addition of a ventilating air flow to the low-gravity flame zone, however, can greatly enhance the flammability range and flame spread. These results, along with observations of flame and smoke characteristics useful for microgravity fire-detection 'signatures', promise to be of considerable value to spacecraft fire-safety designs. The paper summarizes the fire detection and suppression techniques proposed for the Space Station Freedom and discusses both the application of low-gravity combustion knowledge to improve fire protection and the critical needs for further research.

  8. Contributions of Microgravity Test Results to the Design of Spacecraft Fire Safety Systems

    Science.gov (United States)

    Friedman, Robert; Urban, David L.

    1993-01-01

    Experiments conducted in spacecraft and drop towers show that thin-sheet materials have reduced flammability ranges and flame-spread rates under quiescent low-gravity environments (microgravity) as compared to normal gravity. Furthermore, low-gravity flames may be suppressed more easily by atmospheric dilution or decreasing atmospheric total pressure than their normal-gravity counterparts. The addition of a ventilating air flow to the low-gravity flame zone, however, can greatly enhance the flammability range and flame spread. These results, along with observations of flame and smoke characteristics useful for microgravity fire-detection 'signatures', promise to be of considerable value to spacecraft fire-safety designs. The paper summarizes the fire detection and suppression techniques proposed for the Space Station Freedom and discusses both the application of low-gravity combustion knowledge to improve fire protection and the critical needs for further research.

  9. Advanced dependent pressure vessel (DPV) nickel-hydrogen spacecraft battery design

    Energy Technology Data Exchange (ETDEWEB)

    Coates, D.K.; Grindstaff, B.; Swaim, O.; Fox, C. [Eagle-Picher Industries, Inc., Joplin, MO (United States). Advanced Systems Operation

    1995-12-31

    The dependent pressure vessel (DPV) nickel-hydrogen (NiH{sub 2}) battery is being developed as a potential spacecraft battery design for both military and commercial satellites. The limitations of standard NiH{sub 2} individual pressure vessel (IPV) flight battery technology are primarily related to the internal cell design and the battery packaging issues associated with grouping multiple cylindrical cells. The DPV cell design offers higher energy density and reduced cost, while retaining the established IPV technology flight heritage and database. The advanced cell design offers a more efficient mechanical, electrical and thermal cell configuration and a reduced parts count. The geometry of the DPV cell promotes compact, minimum volume packaging and weight efficiency. The DPV battery design offers significant cost and weight savings advantages while providing minimal design risks.

  10. Aerospace Vehicle Design, Spacecraft Section. Final Project Reports. Volume 2; Project Groups 6-8

    Science.gov (United States)

    1989-01-01

    Three groups of student engineers in an aerospace vehicle design course present their designs for a vehicle that can be used to resupply the Space Station Freedam and provide emergency crew return to earth capability. The vehicle's requirements include a lifetime that exceeds six years, low cost, the capability for withstanding pressurization, launch, orbit, and reentry hazards, and reliability. The vehicle's subsystems are structures, communication and command data systems, attitude and articulation control, life support and crew systems, power and propulsion, reentry and recovery systems, and mission management, planning, and costing. Special attention is given to spacecraft communications.

  11. Spacecraft radiator systems

    Science.gov (United States)

    Anderson, Grant A. (Inventor)

    2012-01-01

    A spacecraft radiator system designed to provide structural support to the spacecraft. Structural support is provided by the geometric "crescent" form of the panels of the spacecraft radiator. This integration of radiator and structural support provides spacecraft with a semi-monocoque design.

  12. Dynamic Isotope Power System (DIPS) Applications Study. Volume II. Nuclear Integrated Multimission Spacecraft (NIMS) design definition. Final report

    International Nuclear Information System (INIS)

    1979-11-01

    The design requirements for the Nuclear Integrated Multimission Spacecraft. (NIMS) are discussed in detail. The requirements are a function of mission specifications, payload, control system requirements, electric system specifications, and cost limitations

  13. Design Process of Flight Vehicle Structures for a Common Bulkhead and an MPCV Spacecraft Adapter

    Science.gov (United States)

    Aggarwal, Pravin; Hull, Patrick V.

    2015-01-01

    Design and manufacturing space flight vehicle structures is a skillset that has grown considerably at NASA during that last several years. Beginning with the Ares program and followed by the Space Launch System (SLS); in-house designs were produced for both the Upper Stage and the SLS Multipurpose crew vehicle (MPCV) spacecraft adapter. Specifically, critical design review (CDR) level analysis and flight production drawing were produced for the above mentioned hardware. In particular, the experience of this in-house design work led to increased manufacturing infrastructure for both Marshal Space Flight Center (MSFC) and Michoud Assembly Facility (MAF), improved skillsets in both analysis and design, and hands on experience in building and testing (MSA) full scale hardware. The hardware design and development processes from initiation to CDR and finally flight; resulted in many challenges and experiences that produced valuable lessons. This paper builds on these experiences of NASA in recent years on designing and fabricating flight hardware and examines the design/development processes used, as well as the challenges and lessons learned, i.e. from the initial design, loads estimation and mass constraints to structural optimization/affordability to release of production drawing to hardware manufacturing. While there are many documented design processes which a design engineer can follow, these unique experiences can offer insight into designing hardware in current program environments and present solutions to many of the challenges experienced by the engineering team.

  14. Dual shear plate power processor packaging design. [for Solar Electric Propulsion spacecraft

    Science.gov (United States)

    Franzon, A. O.; Fredrickson, C. D.; Ross, R. G.

    1975-01-01

    The use of solar electric propulsion (SEP) for spacecraft primary propulsion imposes an extreme range of operational and environmental design requirements associated with the diversity of missions for which solar electric primary propulsion is advantageous. One SEP element which is particularly sensitive to these environmental extremes is the power processor unit (PPU) which powers and controls the electric ion thruster. An improved power processor thermal-mechanical packaging approach, referred to as dual shear plate packaging, has been designed to accommodate these different requirements with minimum change to the power processor design. Details of this packaging design are presented together with test results obtained from thermal-vacuum and structural-vibration tests conducted with prototype hardware.

  15. Night vision imaging system design, integration and verification in spacecraft vacuum thermal test

    Science.gov (United States)

    Shang, Yonghong; Wang, Jing; Gong, Zhe; Li, Xiyuan; Pei, Yifei; Bai, Tingzhu; Zhen, Haijing

    2015-08-01

    The purposes of spacecraft vacuum thermal test are to characterize the thermal control systems of the spacecraft and its component in its cruise configuration and to allow for early retirement of risks associated with mission-specific and novel thermal designs. The orbit heat flux is simulating by infrared lamp, infrared cage or electric heater. As infrared cage and electric heater do not emit visible light, or infrared lamp just emits limited visible light test, ordinary camera could not operate due to low luminous density in test. Moreover, some special instruments such as satellite-borne infrared sensors are sensitive to visible light and it couldn't compensate light during test. For improving the ability of fine monitoring on spacecraft and exhibition of test progress in condition of ultra-low luminous density, night vision imaging system is designed and integrated by BISEE. System is consist of high-gain image intensifier ICCD camera, assistant luminance system, glare protect system, thermal control system and computer control system. The multi-frame accumulation target detect technology is adopted for high quality image recognition in captive test. Optical system, mechanical system and electrical system are designed and integrated highly adaptable to vacuum environment. Molybdenum/Polyimide thin film electrical heater controls the temperature of ICCD camera. The results of performance validation test shown that system could operate under vacuum thermal environment of 1.33×10-3Pa vacuum degree and 100K shroud temperature in the space environment simulator, and its working temperature is maintains at 5° during two-day test. The night vision imaging system could obtain video quality of 60lp/mm resolving power.

  16. Hybrid microtransmitter for free-space optical spacecraft communication: design, manufacturing, and characterization

    Science.gov (United States)

    Lotfi, Sara; Palmer, Kristoffer; Kratz, Henrik; Thornell, Greger

    2009-02-01

    Optical intra-communication links are investigated by several currently operational qualification missions. Compared with RF communication systems, the optical domain obtains a wider bandwidth, enables miniaturized spacecraft and reduced power consumption. In this project, a microtransmitter is designed and manufactured for formation flying spacecraft with transmission rates of 1 Gbit/s. Simulations in Matlab and Simulink show that a BER of 10-9 can be achieved with aperture sizes of 1 cm and a transmitter output peak power of 12 mW for a distance of 10 km. The results show that the performance of the communication link decreases due to mechanical vibrations in the spacecraft together with a narrow laser beam. A dual-axis microactuator designed as a deflectable mirror has been developed for the laser beam steering where the fabrication is based on a double-sided, bulk micromachining process. The mirror actuates by joints consisting of v-grooves filled with SU-8 polymer. The deflection is controlled by integrated resistive heaters in the joints causing the polymer to expand thermally. Results show that the mirror actuates 20-30° in the temperature interval 25-250°C. Flat Fresnel lenses made of Pyrex 7740 are used to collimate the laser beam. These lenses are simulated in the Comsol software and optimized for a 670 nm red VCSEL. The lenses are manufactured using lithography and reactive ion etching. All tests are made in a normal laboratory environment, but the effect of the space environment is discussed.

  17. Design of a Thermal Precipitator for the Characterization of Smoke Particles from Common Spacecraft Materials

    Science.gov (United States)

    Meyer, Marit Elisabeth

    2015-01-01

    A thermal precipitator (TP) was designed to collect smoke aerosol particles for microscopic analysis in fire characterization research. Information on particle morphology, size and agglomerate structure obtained from these tests supplements additional aerosol data collected. Modeling of the thermal precipitator throughout the design process was performed with the COMSOL Multiphysics finite element software package, including the Eulerian flow field and thermal gradients in the fluid. The COMSOL Particle Tracing Module was subsequently used to determine particle deposition. Modeling provided optimized design parameters such as geometry, flow rate and temperatures. The thermal precipitator was built and testing verified the performance of the first iteration of the device. The thermal precipitator was successfully operated and provided quality particle samples for microscopic analysis, which furthered the body of knowledge on smoke particulates. This information is a key element of smoke characterization and will be useful for future spacecraft fire detection research.

  18. Designing a Robust Nonlinear Dynamic Inversion Controller for Spacecraft Formation Flying

    Directory of Open Access Journals (Sweden)

    Inseok Yang

    2014-01-01

    Full Text Available The robust nonlinear dynamic inversion (RNDI control technique is proposed to keep the relative position of spacecrafts while formation flying. The proposed RNDI control method is based on nonlinear dynamic inversion (NDI. NDI is nonlinear control method that replaces the original dynamics into the user-selected desired dynamics. Because NDI removes nonlinearities in the model by inverting the original dynamics directly, it also eliminates the need of designing suitable controllers for each equilibrium point; that is, NDI works as self-scheduled controller. Removing the original model also provides advantages of ease to satisfy the specific requirements by simply handling desired dynamics. Therefore, NDI is simple and has many similarities to classical control. In real applications, however, it is difficult to achieve perfect cancellation of the original dynamics due to uncertainties that lead to performance degradation and even make the system unstable. This paper proposes robustness assurance method for NDI. The proposed RNDI is designed by combining NDI and sliding mode control (SMC. SMC is inherently robust using high-speed switching inputs. This paper verifies similarities of NDI and SMC, firstly. And then RNDI control method is proposed. The performance of the proposed method is evaluated by simulations applied to spacecraft formation flying problem.

  19. The Evolution of Software and Its Impact on Complex System Design in Robotic Spacecraft Embedded Systems

    Science.gov (United States)

    Butler, Roy

    2013-01-01

    The growth in computer hardware performance, coupled with reduced energy requirements, has led to a rapid expansion of the resources available to software systems, driving them towards greater logical abstraction, flexibility, and complexity. This shift in focus from compacting functionality into a limited field towards developing layered, multi-state architectures in a grand field has both driven and been driven by the history of embedded processor design in the robotic spacecraft industry.The combinatorial growth of interprocess conditions is accompanied by benefits (concurrent development, situational autonomy, and evolution of goals) and drawbacks (late integration, non-deterministic interactions, and multifaceted anomalies) in achieving mission success, as illustrated by the case of the Mars Reconnaissance Orbiter. Approaches to optimizing the benefits while mitigating the drawbacks have taken the form of the formalization of requirements, modular design practices, extensive system simulation, and spacecraft data trend analysis. The growth of hardware capability and software complexity can be expected to continue, with future directions including stackable commodity subsystems, computer-generated algorithms, runtime reconfigurable processors, and greater autonomy.

  20. Mechanical design and vibro-acoustic testing of ultrathin carbon foils for a spacecraft instrument

    Energy Technology Data Exchange (ETDEWEB)

    Bernardin, John D [Los Alamos National Laboratory; Baca, Allen G [SNL

    2009-01-01

    IBEX-Hi is an electrostatic analyzer spacecraft instrument designed to measure the energy and flux distribution of energetic neutral atoms (ENAs) emanating from the interaction zone between the Earth's solar system and the Milky Way galaxy. A key element to this electro-optic instrument is an array of fourteen carbon foils that are used to ionize the ENAs. The foils are comprised of an ultrathin (50-100 {angstrom} thick) layer of carbon suspended across the surface of an electroformed Nickel wire screen, which in turn is held taught by a metal frame holder. The electro formed orthogonal screen has square wire elements, 12.7 {micro}m thick, with a pitch of 131.1 wires/cm. Each foil holder has an open aperture approximately 5 cm by 2.5 cm. Designing and implementing foil holders with such a large surface area has not been attempted for spaceflight in the past and has proven to be extremely challenging. The delicate carbon foils are subject to fatigue failure from the large acoustic and vibration loads that they will be exposed to during launch of the spacecraft. This paper describes the evolution of the foil holder design from previous space instrument applications to a flight-like IBEX-Hi prototype. Vibro-acoustic qualification tests of the IBEX-Hi prototype instrument and the resulting failure of several foils are summarized. This is followed by a discussion of iterative foil holder design modifications and laser vibrometer modal testing to support future fatigue failure analyses, along with additional acoustic testing of the IBEX-Hi prototype instrument. The results of these design and testing activities are merged and the resulting flight-like foil holder assembly is proposed.

  1. 42: An Open-Source Simulation Tool for Study and Design of Spacecraft Attitude Control Systems

    Science.gov (United States)

    Stoneking, Eric

    2018-01-01

    Simulation is an important tool in the analysis and design of spacecraft attitude control systems. The speaker will discuss the simulation tool, called simply 42, that he has developed over the years to support his own work as an engineer in the Attitude Control Systems Engineering Branch at NASA Goddard Space Flight Center. 42 was intended from the outset to be high-fidelity and powerful, but also fast and easy to use. 42 is publicly available as open source since 2014. The speaker will describe some of 42's models and features, and discuss its applicability to studies ranging from early concept studies through the design cycle, integration, and operations. He will outline 42's architecture and share some thoughts on simulation development as a long-term project.

  2. Modeling Temporal Processes in Early Spacecraft Design: Application of Discrete-Event Simulations for Darpa's F6 Program

    Science.gov (United States)

    Dubos, Gregory F.; Cornford, Steven

    2012-01-01

    While the ability to model the state of a space system over time is essential during spacecraft operations, the use of time-based simulations remains rare in preliminary design. The absence of the time dimension in most traditional early design tools can however become a hurdle when designing complex systems whose development and operations can be disrupted by various events, such as delays or failures. As the value delivered by a space system is highly affected by such events, exploring the trade space for designs that yield the maximum value calls for the explicit modeling of time.This paper discusses the use of discrete-event models to simulate spacecraft development schedule as well as operational scenarios and on-orbit resources in the presence of uncertainty. It illustrates how such simulations can be utilized to support trade studies, through the example of a tool developed for DARPA's F6 program to assist the design of "fractionated spacecraft".

  3. Design and Implementation of Hitl Simulator Coupleing Communications Payload and Software Spacecraft Bus

    Directory of Open Access Journals (Sweden)

    In-Jun Kim

    2003-12-01

    Full Text Available Engineering qualification model payload for a communications and broadcasting satellite(CBS was developed by ETRI from May, 2000 to April, 2003. For the purpose of functional test and verification of the payload, a real-time hardware-in-the-loop(HITL CBS simulator(CBSSIM was also developed. We assumed that the spacecraft platform for the CBSSIM is a geostationary communication satellite using momentum bias three-axis stabilization control technique based on Koreasat. The payload hardware is combined with CBSSIM via Power, Command and Telemetry System(PCTS of Electrical Ground Support Equipment(EGSE. CBSSIM is connected with PCTS by TCP/IP and the payload is combined with PCTS by MIL-STD-1553B protocol and DC harness. This simulator runs under the PC-based simulation environment with Windows 2000 operating system. The satellite commands from the operators are transferred to the payload or bus subsystem models through the real-time process block in the simulator. Design requirements of the CBSSIM are to operate in real-time and generate telemetry. CBSSIM provides various graphic monitoring interfaces and control functions and supports both pre-launch and after-launch of a communication satellite system. In this paper, the HITL simulator system including CBSSIM, communications payload and PCTS as the medium of interface between CBSSIM and communications payload will be described in aspects of the system architecture, spacecraft models, and simulator operation environment.

  4. Toward a new spacecraft optimal design lifetime? Impact of marginal cost of durability and reduced launch price

    Science.gov (United States)

    Snelgrove, Kailah B.; Saleh, Joseph Homer

    2016-10-01

    The average design lifetime of satellites continues to increase, in part due to the expectation that the satellite cost per operational day decreases monotonically with increased design lifetime. In this work, we challenge this expectation by revisiting the durability choice problem for spacecraft in the face of reduced launch price and under various cost of durability models. We first provide a brief overview of the economic thought on durability and highlight its limitations as they pertain to our problem (e.g., the assumption of zero marginal cost of durability). We then investigate the merging influence of spacecraft cost of durability and launch price, and we identify conditions that give rise cost-optimal design lifetimes that are shorter than the longest lifetime technically achievable. For example, we find that high costs of durability favor short design lifetimes, and that under these conditions the optimal choice is relatively robust to reduction in launch prices. By contrast, lower costs of durability favor longer design lifetimes, and the optimal choice is highly sensitive to reduction in launch price. In both cases, reduction in launch prices translates into reduction of the optimal design lifetime. Our results identify a number of situations for which satellite operators would be better served by spacecraft with shorter design lifetimes. Beyond cost issues and repeat purchases, other implications of long design lifetime include the increased risk of technological slowdown given the lower frequency of purchases and technology refresh, and the increased risk for satellite operators that the spacecraft will be technologically obsolete before the end of its life (with the corollary of loss of value and competitive advantage). We conclude with the recommendation that, should pressure to extend spacecraft design lifetime continue, satellite manufacturers should explore opportunities to lease their spacecraft to operators, or to take a stake in the ownership

  5. The design and development of a spacecraft appendage tie down mechanism

    Science.gov (United States)

    Nygren, W. D.; Head, R.

    1985-01-01

    The design and evolution is described of a spacecraft Appendage Tie Down Mechanism (ATDM). Particular emphasis is paid to the mechanical aspects of using dry lubricants to increase the efficiency of acme threads and worm gearing. The ATDM consists of five major components. These are a dc torque motor, a worm gear speed reducer, the tension bolt (or T-bolt), nut capture and centering jaws and the capture nut. In addition, there are several minor components such as limit switch assemblies and an antibackdrive mechanism which couples the drive motor to the worm shaft. A development model of the ATDM in various configurations was under test for some time. In its latest version, it has successfully completed thermal vacuum testing, vibration testing, and extended life testing.

  6. Structured tradeoffs preference elicitation: Evaluating CRWMS design and operations

    International Nuclear Information System (INIS)

    Hartman, H.

    1994-01-01

    Preliminary studies over the past few years have yielded multiple design and operations alternatives for the planned Civilian Radioactive Waste Management System (CRWMS). Waste isolation, pre-closure health and safety, and life cycle cost are among the many factors considered in developing these alternatives. The task of CRWMS designers is complicated by substantial heat and nuclear radiation energy output of the spent nuclear fuel and high level waste intended for disposal in an underground repository. Not only must the usual effectiveness, operability and cost objectives be balanced, but done so in the context of a constantly changing environment. Particular alternatives sometimes are favored by virtue of their outstanding performance relative to one of these factors. The Ultimate success of the potential repository, however, depends on reaching a defensible and traceable final decision through simultaneous and systematic weighing of all relevant factors. This paper documents the outcome of Structured Tradeoffs Preference (STP) elicitation as a method for the simultaneous and systematic weighing of factors relevant to repository thermal loading, waste package (WP) design, and emplacement mode decisions. The study provided a low-cost early indication of directions of further research on CRWMS design and operations likely to be most fruitful. The method of STP elicitation was utilized to avoid potential biases documented in other efforts which use only unstructured decision making, or open-quotes well-considered judgmentclose quotes. The STP elicitation procedure presented here complements the use of a parameter network-model pyramid suggested elsewhere in this proceedings to provide a framework for precisely articulating technical questions needing answers. It also forms an independent crosscheck of systems engineering study results and performance assessment modeling

  7. Design vs. Content: A Study of Adolescent Girls' Website Design Preferences

    Science.gov (United States)

    Agosto, Denise E.

    2004-01-01

    This study considered the utility of gender schema theory in examining girls' website design preferences. It built on a previous study which identified eight website evaluation criteria related to biological sex: collaboration, social connectivity, flexibility, motility, contextuality, personal identification, inclusion, and graphic/multimedia…

  8. Using the Design for Demise Philosophy to Reduce Casualty Risk Due to Reentering Spacecraft

    Science.gov (United States)

    Kelley, R. L.

    2012-01-01

    Recently the reentry of a number of vehicles has garnered public attention due to their risk of human casualty due to fragments surviving reentry. In order to minimize this risk for their vehicles, a number of NASA programs have actively sought to minimize the number of components likely to survive reentry at the end of their spacecraft's life in order to meet and/or exceed NASA safety standards for controlled and uncontrolled reentering vehicles. This philosophy, referred to as "Design for Demise" or D4D, has steadily been adopted, to at least some degree, by numerous programs. The result is that many programs are requesting evaluations of components at the early stages of vehicle design, as they strive to find ways to reduce the number surviving components while ensuring that the components meet the performance requirements of their mission. This paper will discuss some of the methods that have been employed to ensure that the consequences of the vehicle s end-of-life are considered at the beginning of the design process. In addition this paper will discuss the technical challenges overcome, as well as some of the more creative solutions which have been utilized to reduce casualty risk.

  9. Design issues of the piezo motor for the spacecraft reflector control system

    Directory of Open Access Journals (Sweden)

    Azin Anton

    2018-01-01

    Full Text Available Creation of large-size reflectors for spacecrafts is a topical issue for the space industry. The accuracy of the reflecting surface form and the structure weight are the main criteria for the reflector design. The accuracy of the reflecting surface form during a long-term operation is provided by adjustment when using piezoelectric motors in the reflector design. These motors have small weight-size parameters and can reach great torque values. The piezo motor is a distributed mechanical-acoustic oscillation system. Mechanical-acoustic oscillations are generated in the piezo motor by a PZT-stack and transmitted to an oscillator element, and then from the oscillator element to a load action element. At high frequencies, when dimensions of the oscillator are proportionate to the wavelength, the energy is transmitted by means of acoustic waves. In this case, mechanical waves practically are not involved in the energy transmission process. This thesis shows a method for selecting the material of a mechanical-acoustic oscillation system according to the efficiency of the acoustic energy transmission via a piezoelectric layered structure.

  10. Design of Brand Names of Medicines Considering Subjects' Preferences.

    Science.gov (United States)

    Pires, Carla Maria Batista Ferreira; Cavaco, Afonso

    2018-03-01

    Only recently, regulations on the names of medicines were developed. Regulations are mainly focused on avoiding the approval of medicine names that may be confusing to others. Furthermore, legal requirements do not include testing for human factors, such as potential users' preferences. To develop a set of new brand names of medicines, to determine subjects' preferred names, and to evaluate if the linguistic features of these names were related to subjects' preferences. Forty-six new names linguistically equivalent to the Portuguese brand names of medicines were developed. A panel of 13 postgraduates on linguistic studies were purposively enrolled. Participants were required to select and categorize the 6 most preferred names. From the 29 selected names: 62.1% ended in consonants, 65.5% contained at least one syllable of the CVC type, and 62.1% presented final stress. Considering these 3 linguistic features, there were statistically significant differences between the preferred and underpreferred names: χ 2 = 4.572, P = .032; χ 2 = 5.599, P = .018; and χ 2 = 4.572; P = .032, respectively. Some linguistic features of the evaluated names were related to subjects' preferences. Tests on subjects' preferences about the names of medicines may provide additional safety features addressed by the present regulations.

  11. Low Cost Rapid Response Spacecraft, (LCRRS): A Research Project in Low Cost Spacecraft Design and Fabrication in a Rapid Prototyping Environment

    Science.gov (United States)

    Spremo, Stevan; Bregman, Jesse; Dallara, Christopher D.; Ghassemieh, Shakib M.; Hanratty, James; Jackson, Evan; Kitts, Christopher; Klupar, Pete; Lindsay, Michael; Ignacio, Mas; hide

    2009-01-01

    The Low Cost Rapid Response Spacecraft (LCRRS) is an ongoing research development project at NASA Ames Research Center (ARC), Moffett Field, California. The prototype spacecraft, called Cost Optimized Test for Spacecraft Avionics and Technologies (COTSAT) is the first of what could potentially be a series of rapidly produced low-cost satellites. COTSAT has a target launch date of March 2009 on a SpaceX Falcon 9 launch vehicle. The LCRRS research system design incorporates use of COTS (Commercial Off The Shelf), MOTS (Modified Off The Shelf), and GOTS (Government Off The Shelf) hardware for a remote sensing satellite. The design concept was baselined to support a 0.5 meter Ritchey-Chretien telescope payload. This telescope and camera system is expected to achieve 1.5 meter/pixel resolution. The COTSAT team is investigating the possibility of building a fully functional spacecraft for $500,000 parts and $2,000,000 labor. Cost is dramatically reduced by using a sealed container, housing the bus and payload subsystems. Some electrical and RF designs were improved/upgraded from GeneSat-1 heritage systems. The project began in January 2007 and has yielded two functional test platforms. It is expected that a flight-qualified unit will be finished in December 2008. Flight quality controls are in place on the parts and materials used in this development with the aim of using them to finish a proto-flight satellite. For LEO missions the team is targeting a mission class requiring a minimum of six months lifetime or more. The system architecture incorporates several design features required by high reliability missions. This allows for a true skunk works environment to rapidly progress toward a flight design. Engineering and fabrication is primarily done in-house at NASA Ames with flight certifications on materials. The team currently employs seven Full Time Equivalent employees. The success of COTSATs small team in this effort can be attributed to highly cross trained

  12. Design of RTPV generators integrated with new millennium spacecraft for outer solar system

    International Nuclear Information System (INIS)

    Schock, A.; Or, C.; Kumar, V.

    1996-01-01

    The National Aeronautics and Space Administration's recently inaugurated New Millennium program, with its emphasis on miniaturized spacecraft, has generated interest in a low-power (10- to 30-watt), low-mass, high-efficiency RTPV (Radioisotope Thermophotovoltaic) power system. This led to a Department of Energy (DOE)-sponsored design study of such a system. A 75-watt design employed two 250-watt General Purpose Heat Source (GPHS) modules that DOE had previously developed and safety-qualified for various space missions. These modules were too large for the small RTPVs described in this paper. To minimize the need for new development and safety verification studies, derivative designs for 125-watt and 62.5-watt heat source modules containing identical fuel pellets, clads, impact shell, and thermal insulation were generated along with a novel heat source support scheme to reduce the heat losses through the structural supports, and a new and much simpler radiator structure, employing no honeycombs or heat pipes. Previous RTPV study had been based on the use of GaSb PV cells and spectrally selective IR filters. Because of the very encouraging results of system design studies, in the fall of 1994 an experimental program was initiated to develop improved filters and cells, to demonstrate how much improvement can actually be achieved. First priority was given to filter improvements, because our system studies indicated that improved filters would have a much greater effect on system performance than cell improvements. By September 1995 about 94% of the filter performance improvement projected in 1993 had been achieved. (Abstract Truncated)

  13. Learning strategy preferences, verbal-visual cognitive styles, and multimedia preferences for continuing engineering education instructional design

    Science.gov (United States)

    Baukal, Charles Edward, Jr.

    A literature search revealed very little information on how to teach working engineers, which became the motivation for this research. Effective training is important for many reasons such as preventing accidents, maximizing fuel efficiency, minimizing pollution emissions, and reducing equipment downtime. The conceptual framework for this study included the development of a new instructional design framework called the Multimedia Cone of Abstraction (MCoA). This was developed by combining Dale's Cone of Experience and Mayer's Cognitive Theory of Multimedia Learning. An anonymous survey of 118 engineers from a single Midwestern manufacturer was conducted to determine their demographics, learning strategy preferences, verbal-visual cognitive styles, and multimedia preferences. The learning strategy preference profile and verbal-visual cognitive styles of the sample were statistically significantly different than the general population. The working engineers included more Problem Solvers and were much more visually-oriented than the general population. To study multimedia preferences, five of the seven levels in the MCoA were used. Eight types of multimedia were compared in four categories (types in parantheses): text (text and narration), static graphics (drawing and photograph), non-interactive dynamic graphics (animation and video), and interactive dynamic graphics (simulated virtual reality and real virtual reality). The first phase of the study examined multimedia preferences within a category. Participants compared multimedia types in pairs on dual screens using relative preference, rating, and ranking. Surprisingly, the more abstract multimedia (text, drawing, animation, and simulated virtual reality) were preferred in every category to the more concrete multimedia (narration, photograph, video, and real virtual reality), despite the fact that most participants had relatively little prior subject knowledge. However, the more abstract graphics were only slightly

  14. A Hybrid Systems Strategy to Support Autonomous Spacecraft Trajectory Design and Optimization in Multiple Dynamical Regimes

    Data.gov (United States)

    National Aeronautics and Space Administration — With ever increasing numbers of near-Earth satellites and deep space missions, autonomous spacecraft guidance, navigation, and control (GNC) systems are increasingly...

  15. Design and Simulation of a MEMS Control Moment Gyroscope for the Sub-Kilogram Spacecraft

    Directory of Open Access Journals (Sweden)

    Weizheng Yuan

    2010-04-01

    Full Text Available A novel design of a microelectromechanical systems (MEMS control moment gyroscope (MCMG was proposed in this paper in order to generate a torque output with a magnitude of 10-6 N∙m. The MCMG consists of two orthogonal angular vibration systems, i.e., the rotor and gimbal; the coupling between which is based on the Coriolis effect and will cause a torque output in the direction perpendicular to the two vibrations. The angular rotor vibration was excited by the in-plane electrostatic rotary comb actuators, while the angular gimbal vibration was driven by an out-of-plane electrostatic parallel plate actuator. A possible process flow to fabricate the structure was proposed and discussed step by step. Furthermore, an array configuration using four MCMGs as an effective element, in which the torque was generated with a phase difference of 90 degrees between every two MCMGs, was proposed to smooth the inherent fluctuation of the torque output for a vibrational MCMG. The parasitic torque was cancelled by two opposite MCMGs with a phase difference of 180 degrees. The designed MCMG was about 1.1 cm × 1.1 cm × 0.04 cm in size and 0.1 g in weight. The simulation results showed that the maximum torque output of a MCMG, the resonant frequency of which was approximately 1,000 Hz, was about 2.5 × 10-8 N∙m. The element with four MCMGs could generate a torque of 5 × 10-8 N∙m. The torque output could reach a magnitude of 10-6 N∙m when the frequency was improved from 1,000 Hz to 10,000 Hz. Using arrays of 4 × 4 effective elements on a 1 kg spacecraft with a standard form factor of 10 cm × 10 cm × 10 cm, a 10 degrees attitude change could be achieved in 26.96s.

  16. Designing pharmacy services based on grocery store patron preferences.

    Science.gov (United States)

    Lindstrom, Nicolette S Raya; Casper, Kristin A; Green, Tara R; Pedersen, Craig A

    2007-01-01

    To assess preferences of grocery store patrons concerning pharmacy services and identify study participant characteristics that may predict the success of pharmacy services in the community setting. Self-administered survey. Central Ohio from December 16, 2005, to January 12, 2006. 163 grocery store patrons. Eight grocery store survey events. Responses to survey items about (1) perceived importance of 28 pharmacy services, (2) identification of the 3 most important services, (3) frequency of grocery store and pharmacy use, (4) preferred methods of advertising pharmacy services, and (5) socioeconomic demographics. Preferred services delineated by various demographics also were analyzed. A total of 163 surveys were returned from study participants. Nine services appeared in both the top 12 overall preferred services and the 12 highest-ranked services. Statistically significant differences were observed among services ranked as important or very important by age, race, employment, income, caregiver status, and prescription drug coverage status. The three advertising tools selected most frequently included: weekly grocery store ads (68.6%), in-store signs (51.0%), and flyers attached to prescription bags (36.0%). Grocery store patrons would like a wide range of nontraditional pharmacy services that could be implemented into community pharmacies. Pharmacies in grocery stores need to provide both traditional and expanded pharmacy services to meet the desires and expectations of current and potential patients, and expanded marketing methods should be considered.

  17. The impact of aesthetic preference in product design-golden ratio and Korean's preference proportion

    NARCIS (Netherlands)

    Joung, J.Y.; Badke-Schaub, P.G.

    2017-01-01

    Background Over the past decades a considerable number of studies have been done on the golden ratio and the relation between their aesthetics and design. These studies, after analyzing design icons with the golden ratio, seem to prove that the golden ratio is an important principle for good

  18. Design for reliability: NASA reliability preferred practices for design and test

    Science.gov (United States)

    Lalli, Vincent R.

    1994-01-01

    This tutorial summarizes reliability experience from both NASA and industry and reflects engineering practices that support current and future civil space programs. These practices were collected from various NASA field centers and were reviewed by a committee of senior technical representatives from the participating centers (members are listed at the end). The material for this tutorial was taken from the publication issued by the NASA Reliability and Maintainability Steering Committee (NASA Reliability Preferred Practices for Design and Test. NASA TM-4322, 1991). Reliability must be an integral part of the systems engineering process. Although both disciplines must be weighed equally with other technical and programmatic demands, the application of sound reliability principles will be the key to the effectiveness and affordability of America's space program. Our space programs have shown that reliability efforts must focus on the design characteristics that affect the frequency of failure. Herein, we emphasize that these identified design characteristics must be controlled by applying conservative engineering principles.

  19. System Critical Design Audit (CDA). Books 1, 2 and 3; [Small Satellite Technology Initiative (SSTI Lewis Spacecraft Program)

    Science.gov (United States)

    1995-01-01

    Small Satellite Technology Initiative (SSTI) Lewis Spacecraft Program is evaluated. Spacecraft integration, test, launch, and spacecraft bus are discussed. Payloads and technology demonstrations are presented. Mission data management system and ground segment are also addressed.

  20. Progressive addition spectacle lenses: Design preferences and head movements while reading

    Science.gov (United States)

    Preston, Julie Lynn

    In a subjective preference study, two key progressive addition lens parameters, near zone width and corridor length, were varied in a double-masked, randomized, clinical trial of 49 patients. Each subject received a complete eye examination and a new frame. Each wore 6 pairs of lenses for one week at a time and completed questionnaires relating to vision, adaptation, and satisfaction. The preferred lens was identified from the three near zone width lenses and from the three corridor length lenses. Patient characteristics were analyzed for their effect on design preference. Satisfaction ratings following a brief experience with each design were compared to ratings after one week of wear in order to ascertain the predictability of initial impressions. One lens design appeared twice in the preference trial, providing an assessment of the repeatability of the rating instrument. The lens design with the widest near zone was rated significantly lower than the other near zone width designs for nearly every question relating to vision, adaptation, and satisfaction. This lens was also least preferred of all the designs. Preferences for corridor length were evenly distributed among the three designs. Of patient characteristics, years of progressive addition lens wear and gender significantly affected design preference in this population. Initial impressions were not predictive of satisfaction after a week of wear. The rating instrument was judged to have low repeatability. In the head movement portion of the study, 18 participants from the preference study wore the three near zone width designs while reading three paragraphs of varying print size. From a 20 second recording for each of three different paragraphs with each lens, measures of head rotation and posture were collected. The amplitude of head rotation was significantly affected by print size but not by lens design. The effective zone widths on the lenses scanned by the eyes and the locations of the reading levels

  1. Spacecraft operations

    CERN Document Server

    Sellmaier, Florian; Schmidhuber, Michael

    2015-01-01

    The book describes the basic concepts of spaceflight operations, for both, human and unmanned missions. The basic subsystems of a space vehicle are explained in dedicated chapters, the relationship of spacecraft design and the very unique space environment are laid out. Flight dynamics are taught as well as ground segment requirements. Mission operations are divided into preparation including management aspects, execution and planning. Deep space missions and space robotic operations are included as special cases. The book is based on a course held at the German Space Operation Center (GSOC).

  2. NASA reliability preferred practices for design and test

    Science.gov (United States)

    1991-01-01

    Given here is a manual that was produced to communicate within the aerospace community design practices that have contributed to NASA mission success. The information represents the best technical advice that NASA has to offer on reliability design and test practices. Topics covered include reliability practices, including design criteria, test procedures, and analytical techniques that have been applied to previous space flight programs; and reliability guidelines, including techniques currently applied to space flight projects, where sufficient information exists to certify that the technique will contribute to mission success.

  3. Bilevel formulation of a policy design problem considering multiple objectives and incomplete preferences

    Science.gov (United States)

    Hawthorne, Bryant; Panchal, Jitesh H.

    2014-07-01

    A bilevel optimization formulation of policy design problems considering multiple objectives and incomplete preferences of the stakeholders is presented. The formulation is presented for Feed-in-Tariff (FIT) policy design for decentralized energy infrastructure. The upper-level problem is the policy designer's problem and the lower-level problem is a Nash equilibrium problem resulting from market interactions. The policy designer has two objectives: maximizing the quantity of energy generated and minimizing policy cost. The stakeholders decide on quantities while maximizing net present value and minimizing capital investment. The Nash equilibrium problem in the presence of incomplete preferences is formulated as a stochastic linear complementarity problem and solved using expected value formulation, expected residual minimization formulation, and the Monte Carlo technique. The primary contributions in this article are the mathematical formulation of the FIT policy, the extension of computational policy design problems to multiple objectives, and the consideration of incomplete preferences of stakeholders for policy design problems.

  4. NASA preferred reliability-practices for design and test

    Science.gov (United States)

    Lisk, Ronald C.

    1992-01-01

    NASA HQ established the NASA R&M Steering Committee (R&MSC) comprised of membership from each NASA field center. The primary charter of the R&MSC is to obtain, record, and share the best design practices that NASA has applied to successful space flight programs and current design considerations (guidelines) that should enhance flight reliability on emerging programs. The practices and guidelines are being assembled in a living document for distribution to NASA centers and the aerospace community. The document will be updated annually with additional practices and guidelines as contributions from the centers are reviewed and approved by the R&MSC. Practices and guidelines are not requirements, but rather a means of sharing procedures and techniques that a given center and the R&MSC together feel have strong technical merit and application to the design of space-related equipment.

  5. Ring Irrigation System (RIS design through customer preference representation

    Directory of Open Access Journals (Sweden)

    Ridwan Infandra I.Z.

    2018-01-01

    Full Text Available In agricultural field, irrigation is one of the most interesting considerations affecting the rate of plant growth and development. Micro-irrigation as the dripping or sprinkle method is one of the irrigation types that applies the small amount of water for fulfilling the humidity requirement. The most important factors affecting the demand of water for plants are soil conditions and effect of climatic factors. With less human labour required, to improve the irrigation method from the recent days, analyzing water used or water permeation automatically through the soil moisture has been raised as the interesting topic. Proposed in this research is the ring irrigation system (RIS which is introduced as an alternative channel for emitters that drip water directly onto the soil at the plant’s root zone where the soil conditions before and after watering can be quickly detected by the sensors. This RIS can be used for the potted plant, green house, or other small farm fields. Product design and development (PDD is applied in this research for assisting the designer to understand and create the RIS prototype properly according to the customer’s requirements where the suggested functions obtained will be added and tested.

  6. Informing Healthcare Waiting Area Design Using Transparency Attributes: A Comparative Preference Study.

    Science.gov (United States)

    Jiang, Shan; Powers, Matthew; Allison, David; Vincent, Ellen

    2017-07-01

    This study aimed to explore people's visual preference for waiting areas in general hospital environments designed with transparency attributes that fully integrate nature. Waiting can be a tedious and frustrating experience among people seeking healthcare treatments and negatively affect their perception of the quality of care. Positive distractions and supportive designs have gained increasing attraction to improve people's waiting experience. Nature, which has shown therapeutic effects according to a growing amount of evidence, could be a distinguished positive distraction in waiting areas. Additionally, the theory of transparency was operationalized to indicate a spatial continuity between the external nature and the built interiors in general healthcare waiting area design. A survey method was adopted in the study. Twenty-one images of general healthcare waiting areas depicting three design typologies were preselected following a strict procedure, including designs with (a) no window views, (b) limited window views to nature, and (c) transparent spaces with maximum natural views. Ninety-five student participants rated the images based on their visual preference using a Likert-type scale. The results showed that transparent waiting areas were significantly preferred. A significant positive relationship existed between the level of transparency and people's preference scores. The factor analysis indicated additional supportive features that may affect people's preferences, including daylight, perceived warmth, noninstitutional furniture arrangement, visual orientation, and the use of natural materials for interior design. However, these tentative results need to be furthered tested with the real patient population as the next step of this study.

  7. Preferences based Control Design of Complex Fed-batch Cultivation Process

    Directory of Open Access Journals (Sweden)

    Yuri Pavlov

    2009-08-01

    Full Text Available In the paper is presented preferences based control design and stabilization of the growth rate of fed-batch cultivation processes. The control is based on an enlarged Wang-Monod-Yerusalimsky kinetic model. Expected utility theory is one of the approaches for utilization of conceptual information (expert preferences. In the article is discussed utilization of stochastic machine learning procedures for evaluation of expert utilities as criteria for optimization.

  8. Identification of preferred dipole design options and cost estimates: Deliverable D5.2

    CERN Document Server

    Tommasini, Davide

    2017-01-01

    This document contains a description of the preferred 16 Tesla dipole magnet baseline design with its expected performances. The document also includes an analysis of the individual merits and risks of the different, initial design options and gives a justification for the selection of the baseline design. The deliverable includes expected field levels, field errors and a cost estimate, which serve as input for the arc design consolidation.

  9. Students' Preferences and Opinions on Design of a Mobile Marketing Education Application

    Science.gov (United States)

    Ozata, Zeynep; Ozdama Keskin, Nilgun

    2014-01-01

    The purpose of this study was to define and better understand business school students' opinions and preferences on the design of a mobile marketing education application. To accomplish this purpose an explanatory mixed methods study design was used and the data was collected sequentially. First, a questionnaire was conducted with 168 business…

  10. Better Educational Website Interface Design: The Implications from Gender-Specific Preferences in Graduate Students

    Science.gov (United States)

    Hsu, Yu-chang

    2006-01-01

    This study investigated graduate students gender-specific preferences for certain website interface design features, intending to generate useful information for instructors in choosing and for website designers in creating educational websites. The features investigated in this study included colour value, major navigation buttons placement, and…

  11. Advanced composite structures. [metal matrix composites - structural design criteria for spacecraft construction materials

    Science.gov (United States)

    1974-01-01

    A monograph is presented which establishes structural design criteria and recommends practices to ensure the design of sound composite structures, including composite-reinforced metal structures. (It does not discuss design criteria for fiber-glass composites and such advanced composite materials as beryllium wire or sapphire whiskers in a matrix material.) Although the criteria were developed for aircraft applications, they are general enough to be applicable to space vehicles and missiles as well. The monograph covers four broad areas: (1) materials, (2) design, (3) fracture control, and (4) design verification. The materials portion deals with such subjects as material system design, material design levels, and material characterization. The design portion includes panel, shell, and joint design, applied loads, internal loads, design factors, reliability, and maintainability. Fracture control includes such items as stress concentrations, service-life philosophy, and the management plan for control of fracture-related aspects of structural design using composite materials. Design verification discusses ways to prove flightworthiness.

  12. The Effect of Length in Employment Sites’ Web Form Design on User Preferences

    Directory of Open Access Journals (Sweden)

    Yu-Ching Wang

    2014-06-01

    Full Text Available Web form has become a critical component for many Web applications and services. Previous research has investigated into the general design of web form layout without examining the impact of variations in format, length and structure on user experience. This study explores users’ preference and performance over Web forms of different lengths deployed on an employment site. Three types of design of Web forms were developed as the experiment instruments for 48 participants to test and evaluate. Results show that participants’ preferences and satisfaction varied by the length of Web forms. Participants’ preferences were also affected by their previous Internet experiences with job websites. In the end, recommendations for design principles for Web forms used for job sites were presented. [Article content in Chinese

  13. Reliability considerations in long-life outer planet spacecraft system design

    Science.gov (United States)

    Casani, E. K.

    1975-01-01

    A Mariner Jupiter/Saturn mission has been planned for 1977. System reliability questions are discussed, taking into account the actual and design lifetime, causes of mission termination, in-flight failures and their consequences for the mission, and the use of redundancy to avoid failures. The design process employed optimizes the use of proven subsystem and system designs and then makes the necessary improvements to increase the lifetime as required.

  14. Aesthetic design of e-commerce web pages—Complexity, order, and preferences

    NARCIS (Netherlands)

    Poole, M.S.

    2012-01-01

    This study was conducted to understand the perceptual structure of e-commerce webpage visual aesthetics and to provide insight into how physical design features of web pages influence users' aesthetic perception of and preference for web pages. Drawing on the environmental aesthetics, human-computer

  15. MSDT - A Central Executive to Coordinate Rapid Mission and Spacecraft Design, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The integrated design centers currently in place at the Goddard and Ames research institutions are highly productive infrastructures, allowing a group of domain...

  16. Innovation in the teaching of astrophysics and space science - spacecraft design group study

    International Nuclear Information System (INIS)

    Castelli, C

    2003-01-01

    This paper describes how the design of a scientific satellite can be used to provide both a stimulating and effective subject for a physics based group study. The group study divides the satellite into distinct subsystems and small teams of two or three students carry out the detailed design of each subsystem. The aim is to produce a complete satellite system design along with the choice of launch vehicle, orbit and communications system so that all the mission requirements can be met. An important feature of the group study is that it is a student led activity with staff acting as mentors. The development of key skills and important learning outcomes from the group study is discussed along with the method for assessment, structuring and resourcing the study

  17. Aerospace Vehicle Design, Spacecraft Section. Volume 1: Project Groups 3-5

    Science.gov (United States)

    1989-01-01

    Three groups of student engineers in an aerospace vehicle design course present their designs for a vehicle that can be used to resupply the Space Station Freedom and provide an emergency crew return to earth capability. The vehicle's requirements include a lifetime that exceeds six years, low cost, the capability for withstanding pressurization, launch, orbit, and reentry hazards, and reliability. The vehicle's subsystems are analyzed. These subsystems are structures, communication and command data systems, attitude and articulation control, life support and crew systems, power and propulsion, reentry and recovery systems, and mission management, planning, and costing.

  18. The Global Precipitation Measurement (GPM Spacecraft Power System Design and Orbital Performance

    Directory of Open Access Journals (Sweden)

    Dakermanji George

    2017-01-01

    The paper describes the power system design details, its performance to date and the lithium ion battery model that was developed for use in the energy balance analysis and is being used to predict the on-orbit health of the battery.

  19. Spacecraft Attitude Determination

    DEFF Research Database (Denmark)

    Bak, Thomas

    This thesis describes the development of an attitude determination system for spacecraft based only on magnetic field measurements. The need for such system is motivated by the increased demands for inexpensive, lightweight solutions for small spacecraft. These spacecraft demands full attitude...... determination based on simple, reliable sensors. Meeting these objectives with a single vector magnetometer is difficult and requires temporal fusion of data in order to avoid local observability problems. In order to guaranteed globally nonsingular solutions, quaternions are generally the preferred attitude...... is a detailed study of the influence of approximations in the modeling of the system. The quantitative effects of errors in the process and noise statistics are discussed in detail. The third contribution is the introduction of these methods to the attitude determination on-board the Ørsted satellite...

  20. People’s Preferences of Urban Design Qualities for Walking on a Commercial Street

    Science.gov (United States)

    Ernawati, J.; Surjono; Sudarmo, B. S.

    2018-03-01

    This research aims to explore people’s preferences of urban design qualities for walking on a commercial street, with Kawi Street located in a commercial neighborhood in the town of Malang Indonesia as the case study. Based on a literature review, this study used eight urban design qualities, i.e., enclosure, legibility, human scale, transparency, complexity, coherence, linkage, and imageability. This study applied a survey research method using a self-administered paper-pencil questionnaire applying two measurement techniques: Likert scale was used to explore people’s evaluations of urban design qualities of the street, while multiple-rating scales were used to measure people’s preference for walking on the street. One hundred and ten people randomly selected as respondents. Regression analysis was employed to explore the influence of urban design qualities on people preference for walking. Results indicated four urban design qualities that affect people’s choice for walking on a commercial street, i.e., transparency, coherence, linkage, and imageability. Implications of the findings will be discussed in the paper.

  1. Assembly and Design Miniaturization of Floating Spacecraft Simulator and Its Magnetic Docking Interface

    Science.gov (United States)

    2016-09-01

    10cm with minimal height, using a static mount instead of a ball mounting screw end would mitigate this concern. Figure 24. New Way Air Bearing...required if the air being used to fill the tank is from a 40 compressor designed for scuba tanks, as is the case in the SRL, it may be prudent to...tape to the bottom. 65 Step (12) Screw the assembled tank filler attachment to the air tank

  2. Using contingent choice methods to assess consumer preferences about health plan design.

    Science.gov (United States)

    Marquis, M Susan; Buntin, Melinda Beeuwkes; Kapur, Kanika; Yegian, Jill M

    2005-01-01

    American insurers are designing products to contain health care costs by making consumers financially responsible for their choices. Little is known about how consumers will view these new designs. Our objective is to examine consumer preferences for selected benefit designs. We used the contingent choice method to assess willingness to pay for six health plan attributes. Our sample included subscribers to individual health insurance products in California, US. We used fitted logistic regression models to explore how preferences for the more generous attributes varied with the additional premium and with the characteristics of the subscriber. High quality was the most highly valued attribute based on the amounts consumers report they are willing to pay. They were also willing to pay substantial monthly premiums to reduce their overall financial risk. Individuals in lower health were willing to pay more to reduce their financial risk than individuals in better health. Consumers may prefer tiered-benefit designs to those that involve overall increases in cost sharing. More consumer information is needed to help consumers better evaluate the costs and benefits of their insurance choices.

  3. Testing of an End-Point Control Unit Designed to Enable Precision Control of Manipulator-Coupled Spacecraft

    Science.gov (United States)

    Montgomery, Raymond C.; Ghosh, Dave; Tobbe, Patrick A.; Weathers, John M.; Manouchehri, Davoud; Lindsay, Thomas S.

    1994-01-01

    This paper presents an end-point control concept designed to enable precision telerobotic control of manipulator-coupled spacecraft. The concept employs a hardware unit (end-point control unit EPCU) that is positioned between the end-effector of the Space Shuttle Remote Manipulator System and the payload. Features of the unit are active compliance (control of the displacement between the end-effector and the payload), to allow precision control of payload motions, and inertial load relief, to prevent the transmission of loads between the end-effector and the payload. This paper presents the concept and studies the active compliance feature using a simulation and hardware. Results of the simulation show the effectiveness of the EPCU in smoothing the motion of the payload. Results are presented from initial, limited tests of a laboratory hardware unit on a robotic arm testbed at the l Space Flight Center. Tracking performance of the arm in a constant speed automated retraction and extension maneuver of a heavy payload with and without the unit active is compared for the design speed and higher speeds. Simultaneous load reduction and tracking performance are demonstrated using the EPCU.

  4. Guidelines for the Selection of Near-Earth Thermal Environment Parameters for Spacecraft Design

    Science.gov (United States)

    Anderson, B. J.; Justus, C. G.; Batts, G. W.

    2001-01-01

    Thermal analysis and design of Earth orbiting systems requires specification of three environmental thermal parameters: the direct solar irradiance, Earth's local albedo, and outgoing longwave radiance (OLR). In the early 1990s data sets from the Earth Radiation Budget Experiment were analyzed on behalf of the Space Station Program to provide an accurate description of these parameters as a function of averaging time along the orbital path. This information, documented in SSP 30425 and, in more generic form in NASA/TM-4527, enabled the specification of the proper thermal parameters for systems of various thermal response time constants. However, working with the engineering community and SSP-30425 and TM-4527 products over a number of years revealed difficulties in interpretation and application of this material. For this reason it was decided to develop this guidelines document to help resolve these issues of practical application. In the process, the data were extensively reprocessed and a new computer code, the Simple Thermal Environment Model (STEM) was developed to simplify the process of selecting the parameters for input into extreme hot and cold thermal analyses and design specifications. In the process, greatly improved values for the cold case OLR values for high inclination orbits were derived. Thermal parameters for satellites in low, medium, and high inclination low-Earth orbit and with various system thermal time constraints are recommended for analysis of extreme hot and cold conditions. Practical information as to the interpretation and application of the information and an introduction to the STEM are included. Complete documentation for STEM is found in the user's manual, in preparation.

  5. Students’ Preferences And Opinions On Design 
Of A Mobile Marketing Education Application

    Directory of Open Access Journals (Sweden)

    F. Zeynep OZATA

    2014-01-01

    Full Text Available The purpose of this study was to define and better understand business school students’ opinions and preferences on the design of a mobile marketing education application. To accomplish this purpose an explanatory mixed methods study design was used and the data was collected sequentially. First, a questionnaire was conducted with 168 business school students from Anadolu University to define their learning styles. The learning orientation questionnaire produced five factors: visual, auditory, dependent, collaborative, and reading & writing learning styles. In the second phase of the study, semi-structured in depth interviews were conducted with nine graduate students at Anadolu University to better understand their preferences and explore their opinions on the mobile application. After the coding process three themes emerged: learning styles, content, and tools. Added to these themes, eight motives for the use of a mobile marketing education application were also identified.

  6. Spacecraft Charging Considerations and Design Efforts for the Orion Crew Module

    Science.gov (United States)

    Scully, Bob

    2017-01-01

    The Orion Crew Module (CM) is nearing completion for the next flight, designated as Exploration Mission 1 (EM-1). For the uncrewed mission, the flight path will take the CM through a Perigee Raise Maneuver (PRM) out to an altitude of approximately 1800 km, followed by a Trans-Lunar Injection burn, a pass through the Van Allen belts then out to the moon for a lunar flyby, a Distant Retrograde Insertion (DRI) burn, a Distant Retrograde Orbit (DRO), a Distant Retrograde Departure (DRD) burn, a second lunar flyby, an Earth Insertion (EI) burn, and finally entry and landing. All of this, with the exception of the DRO associated maneuvers, is similar to the previous Apollo 8 mission in late 1968. In recent discussions, it is now possible that EM-1 will be a crewed mission, and if this happens, the orbit may be quite different from that just described. In this case, the flight path may take the CM on an out and back pass through the Van Allen belts twice, then out to the moon, again passing through the Van Allen belts twice, then finally back home. Even if the current EM-1 mission doesn't end up as a crewed mission, EM-2 and subsequent missions will undoubtedly follow orbital trajectories that offer comparable exposures to heightened vehicle charging effects. Because of this, and regardless of flight path, the CM vehicle will likely experience a wide range of exposures to energetic ions and electrons, essentially covering the gamut between low earth orbit to geosynchronous orbit and beyond. National Aeronautical and Space Administration (NASA) and Lockheed Martin (LM) engineers and scientists have been working to fully understand and characterize the vehicle's immunity level with regard to surface and deep dielectric charging, and the ramifications of that immunity level pertaining to materials and impacts to operational avionics, communications, and navigational systems. This presentation attempts to chronicle these efforts in a summary fashion, and attempts to capture

  7. An Empirical Study of Parameter Estimation for Stated Preference Experimental Design

    Directory of Open Access Journals (Sweden)

    Fei Yang

    2014-01-01

    Full Text Available The stated preference experimental design can affect the reliability of the parameters estimation in discrete choice model. Some scholars have proposed some new experimental designs, such as D-efficient, Bayesian D-efficient. But insufficient empirical research has been conducted on the effectiveness of these new designs and there has been little comparative analysis of the new designs against the traditional designs. In this paper, a new metro connecting Chengdu and its satellite cities is taken as the research subject to demonstrate the validity of the D-efficient and Bayesian D-efficient design. Comparisons between these new designs and orthogonal design were made by the fit of model and standard deviation of parameters estimation; then the best model result is obtained to analyze the travel choice behavior. The results indicate that Bayesian D-efficient design works better than D-efficient design. Some of the variables can affect significantly the choice behavior of people, including the waiting time and arrival time. The D-efficient and Bayesian D-efficient design for MNL can acquire reliability result in ML model, but the ML model cannot develop the theory advantages of these two designs. Finally, the metro can handle over 40% passengers flow if the metro will be operated in the future.

  8. Design of a mission network system using SpaceWire for scientific payloads onboard the Arase spacecraft

    Science.gov (United States)

    Takashima, Takeshi; Ogawa, Emiko; Asamura, Kazushi; Hikishima, Mitsuru

    2018-05-01

    Arase is a small scientific satellite program conducted by the Institute of Space and Astronautical Science/Japan Aerospace Exploration Agency, which is dedicated to the detailed study of the radiation belts around Earth through in situ observations. In particular, the goal is to directly observe the interaction between plasma waves and particles, which cause the generation of high-energy electrons. To observe the waves and particles in detail, we must record large volumes of burst data with high transmission rates through onboard mission network systems. For this purpose, we developed a high-speed and highly reliable mission network based on SpaceWire, as well as a new and large memory data recorder equipped with a data search function based on observation time (the time index, TI, is the satellite time starting from when the spacecraft is powered on.) with respect to the orbital data generated in large quantities. By adopting a new transaction concept of a ring topology network with SpaceWire, we could secure a redundant mission network system without using large routers and having to suppress the increase in cable weight. We confirmed that their orbit performs as designed.[Figure not available: see fulltext.

  9. Design Team communication and Design Task Complexity, the Preference for Dialogus

    NARCIS (Netherlands)

    Otter, den A.F.H.J.; Emmitt, S.

    2008-01-01

    The way in which dialogues and group meetings affect the progress of multidisciplinary architectural design teams can be easily underestimated by managers. This is due to the importance of group meetings to review designs, share information, make decisions and hence progress the design. The aim of

  10. Guidance and Navigation Software Architecture Design for the Autonomous Multi-Agent Physically Interacting Spacecraft (AMPHIS) Test Bed

    National Research Council Canada - National Science Library

    Eikenberry, Blake D

    2006-01-01

    .... This thesis contributes to this on-going research by addressing the development of the software architecture for the AMPHIS spacecraft simulator robots and the implementation of a Light Detection and Ranging (LIDAR...

  11. The influence of gender and product design on farmers' preferences for weather-indexed crop insurance.

    Science.gov (United States)

    Akter, Sonia; Krupnik, Timothy J; Rossi, Frederick; Khanam, Fahmida

    2016-05-01

    Theoretically, weather-index insurance is an effective risk reduction option for small-scale farmers in low income countries. Renewed policy and donor emphasis on bridging gender gaps in development also emphasizes the potential social safety net benefits that weather-index insurance could bring to women farmers who are disproportionately vulnerable to climate change risk and have low adaptive capacity. To date, no quantitative studies have experimentally explored weather-index insurance preferences through a gender lens, and little information exists regarding gender-specific preferences for (and constraints to) smallholder investment in agricultural weather-index insurance. This study responds to this gap, and advances the understanding of preference heterogeneity for weather-index insurance by analysing data collected from 433 male and female farmers living on a climate change vulnerable coastal island in Bangladesh, where an increasing number of farmers are adopting maize as a potentially remunerative, but high-risk cash crop. We implemented a choice experiment designed to investigate farmers' valuations for, and trade-offs among, the key attributes of a hypothetical maize crop weather-index insurance program that offered different options for bundling insurance with financial saving mechanisms. Our results reveal significant insurance aversion among female farmers, irrespective of the attributes of the insurance scheme. Heterogeneity in insurance choices could however not be explained by differences in men's and women's risk and time preferences, or agency in making agriculturally related decisions. Rather, gendered differences in farmers' level of trust in insurance institutions and financial literacy were the key factors driving the heterogeneous preferences observed between men and women. Efforts to fulfill gender equity mandates in climate-smart agricultural development programs that rely on weather-index insurance as a risk-abatement tool are therefore

  12. Service design attributes affecting diabetic patient preferences of telemedicine in South Korea.

    Science.gov (United States)

    Park, Hayoung; Chon, Yucheong; Lee, Jongsu; Choi, Ie-Jung; Yoon, Kun-Ho

    2011-01-01

    Attempts to introduce telemedicine in South Korea have failed mostly, leaving critical questions for service developers and providers about whether patients would be willing to pay for the service and how the service should be designed to encourage patient buy-in. In this study, we explore patients' valuations and preferences for each attribute of telemedicine service for diabetes management and evaluate patient willingness to pay for specific service attributes. We conducted a conjoint survey to collect data on patients' stated preferences among telemedicine service alternatives. The alternatives for diabetes-related service differed in 10 attributes, including those related to price, type of service provider, and service scope. To estimate the relative importance of attributes, patients' willingness to pay for each attribute, and their probable choice of specific alternatives, we used a rank-ordered logit model. A total of 118 respondents participated in the survey. All 10 attributes significantly affected patients' valuations and preferences, and demographic and disease characteristics, such as existence of complications and comorbidities, significantly affected patients' valuations of the attributes. Price was the most important attribute, followed by comprehensive scope of service, the availability of mobile phone-based delivery, and large general-hospital provided services. The study findings have significant implications for adoption policy and strategy of telemedicine in diabetes management care. Further, the methodology presented in this study can be used to draw knowledge needed to formulate effective policy for adoption of the necessary technology and for the design of services that attract potential beneficiaries.

  13. Safety sign designs for children by considering effect of the colors preferences: A case study

    Science.gov (United States)

    Iftadi, Irwan; Nugraha, Dian Cahya; Jauhari, Wakhid Ahmad

    2018-02-01

    Color has become a major consideration in ergonomics. Color conveys a message and it is an important element in safety signs. The importance of colors usage in safety sign designs makes the colors research into one of the things that must be done before designing them. So far, research in the related field only focused on the adult's perspective without involving children's perspective in designing the safety signs. This paper aims to find out how children's perception towards colors affects the safety sign designs. This study consist of eight sections which are literature study, direct observation, determining referents and other parameters, determining research respondents, making the booklet, assessing the colors preferences, determining the design's parameter value and creating the safety sign designs. Limitation of the research are the objects are the students with the age of 10 - 11 years old in Grade IV and then the research is conducted in the school day and hours that apply to the school. Chi square test and odds ratio are employed to assess the colors preferences. Twelve safety sign designs are proposed by considering the children's colors perception. The designs are grouped into three types of sign which are Mandatory Action Sign, Warning Sign and Prohibition Sign. Six colors are used to draw the safety signs i.e. red, orange, yellow, green, blue and black. On the basis of the study, it is concluded that the colors that often appears in safety signs is green with the percentage of 75% and that rarely appears is red with the percentage of 8.33%.

  14. Interior design preferences of residents, families, and staff in two nursing homes.

    Science.gov (United States)

    Miller, D B; Goldman, L E; Woodman, S A

    1985-01-01

    The small number of respondents and the absence of specific demographic data concerning the three categories of respondents represented definite limitations. Further investigation in other long-term care facilities clearly is indicated. However, as a preliminary survey of preferences in nursing home interior design, several interesting findings have emerged: Patients, staff and families all emphasized patient safety and function over aesthetics. Yet, more residents than staff and families were concerned with appearance. Although experts advocate creating a home-like atmosphere in the nursing home, 50% or more of each group applied different criteria for specific design elements for private homes and for long-term care institutions. Design preferences for the three groups were similar, with an emphasis on modern furniture, painted walls, resilient tile rather than carpet, blinds, pastel and warm colors, and the use of paintings as accessories. Contrary to study assumptions, design features that promote patient individuality (e.g., patient artwork) received much greater emphasis from staff than from patients and families. Environmental change was considered an important aspect of interior design. Of the three constituencies, staff was most aware of periodic changes in decor and considered change as "very important" more often than did families or patients. As the nature of the nursing home patient population has changed--with residents presenting more disability and less rehabilitation potential and less likelihood of returning home--the ambiance of facilities has assumed even more importance. Clearly, the design preferences of residents who live in the facility are of paramount importance. However, it is also helpful to have an environment that is pleasing to family members who often experience difficulty in ongoing visitations, particularly to intellectually impaired relatives. Maintaining staff morale at a high level is a constant challenge in a long-term care

  15. Low-floor bus design preferences of walking aid users during simulated boarding and alighting.

    Science.gov (United States)

    D'souza, Clive; Paquet, Victor; Lenker, James; Steinfeld, Edward; Bareria, Piyush

    2012-01-01

    Low-floor buses represent a significant improvement in accessible public transit for passengers with limited mobility. However, there is still a need for research on the inclusive design of transit buses to identify specific low-floor bus design conditions that are either particularly accommodating or challenging for passengers with functional and mobility impairments. These include doorway locations, seating configuration and the large front wheel-well covers that collectively impact boarding, alighting and interior movement of passengers. Findings from a laboratory study using a static full-scale simulation of a lowfloor bus to evaluate the impact of seating configuration and crowding on interior movement and accessibility for individuals with and without walking aids are presented (n=41). Simulated bus journeys that included boarding, fare payment, seating, and alighting were performed. Results from video observations and subjective assessments showed differences in boarding and alighting performance and users' perceptions of task difficulty. The need for assistive design features (e.g. handholds, stanchions), legroom and stowage space for walking aids was evident. These results demonstrate that specific design conditions in low-floor buses can significantly impact design preference among those who use walking aids. Consideration of ergonomics and inclusive design can therefore be used to improve the design of low-floor buses.

  16. Forming a method mindset: The role of knowledge and preference in facilitating heuristic method usage in design

    DEFF Research Database (Denmark)

    Daalhuizen, Jaap; Person, Oscar; Gattol, Valentin

    2013-01-01

    Both systematic and heuristic methods are common practice when designing. Yet, in teaching students how to design, heuristic methods are typically only granted a secondary role. So, how do designers and students develop a mindset for using heuristic methods? In this paper, we study how prior...... knowledge (about heuristic methods and their usage) and preference (for using heuristic methods) relate to the reported use of heuristic methods when designing. Drawing on a survey among 304 students enrolled in a master-level course on design theory and methodology, we investigated method usage for five...... indirectly influenced method usage through a 'complementary' mediation of method preference....

  17. Dips spacecraft integration issues

    International Nuclear Information System (INIS)

    Determan, W.R.; Harty, R.B.

    1988-01-01

    The Department of Energy, in cooperation with the Department of Defense, has recently initiated the dynamic isotope power system (DIPS) demonstration program. DIPS is designed to provide 1 to 10 kW of electrical power for future military spacecraft. One of the near-term missions considered as a potential application for DIPS was the boost surveillance and tracking system (BSTS). A brief review and summary of the reasons behind a selection of DIPS for BSTS-type missions is presented. Many of these are directly related to spacecraft integration issues; these issues will be reviewed in the areas of system safety, operations, survivability, reliability, and autonomy

  18. Quick Spacecraft Thermal Analysis Tool, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — For spacecraft design and development teams concerned with cost and schedule, the Quick Spacecraft Thermal Analysis Tool (QuickSTAT) is an innovative software suite...

  19. Extending coverage to informal sector populations in Kenya: design preferences and implications for financing policy.

    Science.gov (United States)

    Okungu, Vincent; Chuma, Jane; Mulupi, Stephen; McIntyre, Diane

    2018-01-09

    Universal health coverage (UHC) is important in terms of improving access to quality health care while protecting households from the risk of catastrophic health spending and impoverishment. However, progress to UHC has been hampered by the measures to increase mandatory prepaid funds especially in low- and middle-income countries where there are large populations in the informal sector. Important considerations in expanding coverage to the informal sector should include an exploration of the type of prepayment system that is acceptable to the informal sector and the features of such a design that would encourage prepayment for health care among this population group. The objective of the study was to document the views of informal sector workers regarding different prepayment mechanisms, and critically analyze key design features of a future health system and the policy implications of financing UHC in Kenya. This was part of larger study which involved a mixed-methods approach. The following tools were used to collect data from informal sector workers: focus group discussions [N = 16 (rural = 7; urban = 9)], individual in-depth interviews [N = 26 (rural = 14; urban = 12)] and a questionnaire survey [N = 455(rural = 129; urban = 326)]. Thematic approach was used to analyze qualitative data while Stata v.11 involving mainly descriptive analysis was used in quantitative data. The tools mentioned were used to collect data to meet various objectives of a larger study and what is presented here constitutes a small section of the data generated by these tools. The findings show that informal sector workers in rural and urban areas prefer different prepayment systems for financing UHC. Preference for a non-contributory system of financing UHC was particularly strong in the urban study site (58%). Over 70% in the rural area preferred a contributory mechanism in financing UHC. The main concern for informal sector workers regardless of

  20. [Patient-related color preference and color design in the hospital].

    Science.gov (United States)

    Schuschke, G; Christiansen, H

    1994-06-01

    Colour-physiological studies involving volunteers and colour-psychological interviewing of patients with varied diagnoses revealed that, currently, no compelling scientific reasons can be given for coloration in the hospital. Interviewing 68 patients from a number of clinics on the coloration of sick-rooms yielded the following preferred colours, irrespective of the patients' classing into groups by various criteria: Light colours were consistently preferred for all objects such as ceiling, walls, floor, curtains, furniture, and bed linen. It should be emphasized that even white was a desirable colour for ceilings and bed linen. Beige was found to rank first for walls, floors, curtains, and furniture, whereas the colours of wood and grey shared the second rank for floors and furniture. Green and pink ranked second for bed linen. White and green ranked second for walls and curtains, respectively. In view of the heterogeneity, the findings may not be converted into an absolute just as the recommendations by other workers. Still, the patients' wish should be given priority over decreed recommendations by experts when basic considerations of illumination (reflectance!) are allowed for in the particular overall colour design project.

  1. Contingency Trajectory Design for a Lunar Orbit Insertion Maneuver Failure by the Lunar Atmosphere Dust Environment Explorer (LADEE) Spacecraft

    Science.gov (United States)

    Genova, Anthony L.; Loucks, Michael; Carrico, John

    2014-01-01

    The purpose of this extended abstract is to present results from a failed lunar-orbit insertion (LOI) maneuver contingency analysis for the Lunar Atmosphere Dust Environment Explorer (LADEE) mission, managed and operated by NASA Ames Research Center in Moffett Field, CA. The LADEE spacecrafts nominal trajectory implemented multiple sub-lunar phasing orbits centered at Earth before eventually reaching the Moon (Fig. 1) where a critical LOI maneuver was to be performed [1,2,3]. If this LOI was missed, the LADEE spacecraft would be on an Earth-escape trajectory, bound for heliocentric space. Although a partial mission recovery is possible from a heliocentric orbit (to be discussed in the full paper), it was found that an escape-prevention maneuver could be performed several days after a hypothetical LOI-miss, allowing a return to the desired science orbit around the Moon without leaving the Earths sphere-of-influence (SOI).

  2. An Exploration into Framing Effects and Information Preferences: Implications for the Design of Energy Feedback Interfaces

    Science.gov (United States)

    Taylor-Brown, Peter

    A recent topic in the energy industry involves developing strategies to reduce the necessary peak production capacity of our future electricity infrastructure. One of these strategies is promoting behavioral change among individual energy consumers. An inherent problem with electricity consumption is that electricity is invisible, intangible, and abstract. Interfaces that provide people with useful feedback on their usage can help with understanding and reduction of consumption. These interfaces intend to empower individuals with ability to adopt less wasteful energy consumption behaviors. Skillful HCI design will include attention to informational preferences, and framing effects due to presentation choices. An online questionnaire was utilized to explore this domain, and the results identified design requirements for a home feedback interface. The final dataset contained responses from 36 male and 49 female United States residents. Cost () was perceived as the most useful metric and kW as the least useful. Respondent preference was expressed for lower levels of automation, which was not attributable to distrust of automation. Further, a test of framings effects showed a higher likelihood to change behavior to save 100 dollars per year than 2 per week (U=1248.5, p=0.001). A feedback interface design based on the questionnaire results was used in the second phase of the research. A 2x2x2 factorial design compared the effects of goal-type (specific vs. open-ended), metric-use ( vs. kWh), and visualization (graphical vs. text-only) on user experience, learning and behavior during a consumption reduction task. Results showed that goal-type affects the amount of diagnostic behavior conducted by participants (U=351.0, p=0.001). Goal-type and metric-use independently affect participant belief that they could reduce their consumption in their real home with the same feedback shown in the task, F(df=1,39)=24.77, p=0.001; F(df=1,39)=5.55, p=0.05. In addition, visualization

  3. Designing Spacecraft and Mission Operations Plans to Meet Flight Crew Radiation Dose Requirements: Why is this an "Epic Challenge" for Long-Term Manned Interplanetary Flight

    Science.gov (United States)

    Koontz, Steven

    2012-01-01

    Outline of presentation: (1) Radiation Shielding Concepts and Performance - Galactic Cosmic Rays (GCRs) (1a) Some general considerations (1b) Galactic Cosmic Rays (2)GCR Shielding I: What material should I use and how much do I need? (2a) GCR shielding materials design and verification (2b) Spacecraft materials point dose cosmic ray shielding performance - hydrogen content and atomic number (2c) Accelerator point dose materials testing (2d) Material ranking and selection guidelines (2e) Development directions and return on investment (point dose metric) (2f) Secondary particle showers in the human body (2f-1) limited return of investment for low-Z, high-hydrogen content materials (3) GCR shielding II: How much will it cost? (3a) Spacecraft design and verification for mission radiation dose to the crew (3b) Habitat volume, shielding areal density, total weight, and launch cost for two habitat volumes (3c) It's All about the Money - Historical NASA budgets and budget limits (4) So, what can I do about all this? (4a) Program Design Architecture Trade Space (4b) The Vehicle Design Trade Space (4c) Some Near Term Recommendations

  4. “天宫一号”目标飞行器信息管理策略%Design of information management strategy for Tiangong-1 target spacecraft

    Institute of Scientific and Technical Information of China (English)

    柏林厚; 李智勇; 南洪涛; 程伟

    2013-01-01

    “天宫一号”目标飞行器信息系统作为目标飞行器的重要功能系统,主要完成目标飞行器内部信息管理以及与地面和载人飞船的通信管理,确保目标飞行器的健康和稳定运行,支持目标飞行器各项任务的完成.文章对“天宫一号”目标飞行器信息系统的信息管理策略进行了概述,包括信息管理需求、设计原则、系统组成、主要技术特点以及可靠性安全性设计.“天宫一号”目标飞行器信息系统的信息管理策略经过首次无人和有人交会对接任务验证,满足任务要求,为后续空间站信息系统详细设计奠定了基础.%As the key functional system of the Tiangong-1 target spacecraft, the information management system is mainly responsible for the management of the internal information and the communication with the earth station and the Shenzhou spaceship, to ensure the target spacecraft's stable working and to support the accomplishment of the mission. This paper reviews the design of this target spacecraft information management strategy, including the information requirements, the design principle, the system configuration, the technical characteristics, and the reliability and safety design. With the accomplishment of China's first unmanned and manned rendezvous and docking mission, the information management strategy is demonstrated to fulfill the requirements. The information management system design of the Tiangong-1 target spacecraft lays the foundation for the specific design of China's future space station.

  5. E-Cigarette Design Preference and Smoking Cessation: A U.S. Population Study.

    Science.gov (United States)

    Chen, Caroline; Zhuang, Yue-Lin; Zhu, Shu-Hong

    2016-09-01

    Electronic cigarette (e-cigarette) designs may be described as "closed" or "open." Closed systems are disposable or reloadable with prefilled cartridges (cigalikes). Open systems feature a prominent chamber (tank), refillable with e-liquid. This study examined user design preference and its association with smoking cessation. A probability sample of current e-cigarette users (n=923) among adult ever smokers (n=6,560) in the U.S. was surveyed online between February 28 and March 31, 2014, and analyzed in September 2014. Photos of e-cigarette devices were presented alongside survey questions to facilitate respondents' understanding of the questions. Most e-cigarette users were exclusive users of one design: 51.4% used only closed systems and 41.1% used only open systems, with 7.4% using both. Former smokers were more likely to use open systems than current smokers (53.8% vs 35.2%, p=0.002). Current smokers who attempted to quit in the last 12 months were more likely to use open systems than those who did not (41.4% vs 27.7%, p=0.029). Open system users were more likely than closed system users to use e-cigarettes daily (50.2% vs 22.9%, pe-cigarette design is associated with smoking cessation. A device's ability to deliver more nicotine and its flexibility in use might contribute to users' success in quitting smoking. Copyright © 2016 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

  6. Designer's approach for scene selection in tests of preference and restoration along a continuum of natural to manmade environments

    Science.gov (United States)

    Hunter, MaryCarol R.; Askarinejad, Ali

    2015-01-01

    It is well-established that the experience of nature produces an array of positive benefits to mental well-being. Much less is known about the specific attributes of green space which produce these effects. In the absence of translational research that links theory with application, it is challenging to design urban green space for its greatest restorative potential. This translational research provides a method for identifying which specific physical attributes of an environmental setting are most likely to influence preference and restoration responses. Attribute identification was based on a triangulation process invoking environmental psychology and aesthetics theories, principles of design founded in mathematics and aesthetics, and empirical research on the role of specific physical attributes of the environment in preference or restoration responses. From this integration emerged a list of physical attributes defining aspects of spatial structure and environmental content found to be most relevant to the perceptions involved with preference and restoration. The physical attribute list offers a starting point for deciphering which scene stimuli dominate or collaborate in preference and restoration responses. To support this, functional definitions and metrics—efficient methods for attribute quantification are presented. Use of these research products and the process for defining place-based metrics can provide (a) greater control in the selection and interpretation of the scenes/images used in tests of preference and restoration and (b) an expanded evidence base for well-being designers of the built environment. PMID:26347691

  7. 长期飞行载人航天器适居性设计与分析%Study on Habitability Design of Long Duration Manned Spacecraft

    Institute of Scientific and Technical Information of China (English)

    周前祥

    2012-01-01

    With the successful rendezvous and docking between Shenzhou-8 spaceship and Tiangong-1 spacecraft, habitability design and ergonomic analysis of long duration manned spacecraft will become the main technological problem. The present habitability study of ISS is described in detail, and the status of NASA's study in habitability are analyzed. The main contents of habitability ergonomic design are explored, with some views put forward for discussion.%随着神舟八号飞船与天宫一号的成功对接,长期飞行栽人航天器的适居性设计与应用将成为我国:载人航天技术发展面临的主要技术问题。首先对国际空间站上有关适居性的概况和NASA的研究现状进行了分析。在此基础上,归纳出长期载人航天器适居性设计的主要内容。最后,提出几点看法。

  8. Workshop Synthesis: Stated Preference Surveys and Experimental Design, an Audit of the Journey so far and Future Research Perspectives

    DEFF Research Database (Denmark)

    Cherchi, Elisabetta; Hensher, David A.

    2015-01-01

    This paper is a synthesis of the discussions and ideas that were generated during the workshop on “Stated preference surveys and experimental design” at the 2014 Travel Survey Methods Conference in Leura (Australia). The workshop addressed the challenges related to the design and implementation o...

  9. Spacecraft Thermal Management

    Science.gov (United States)

    Hurlbert, Kathryn Miller

    2009-01-01

    In the 21st century, the National Aeronautics and Space Administration (NASA), the Russian Federal Space Agency, the National Space Agency of Ukraine, the China National Space Administration, and many other organizations representing spacefaring nations shall continue or newly implement robust space programs. Additionally, business corporations are pursuing commercialization of space for enabling space tourism and capital business ventures. Future space missions are likely to include orbiting satellites, orbiting platforms, space stations, interplanetary vehicles, planetary surface missions, and planetary research probes. Many of these missions will include humans to conduct research for scientific and terrestrial benefits and for space tourism, and this century will therefore establish a permanent human presence beyond Earth s confines. Other missions will not include humans, but will be autonomous (e.g., satellites, robotic exploration), and will also serve to support the goals of exploring space and providing benefits to Earth s populace. This section focuses on thermal management systems for human space exploration, although the guiding principles can be applied to unmanned space vehicles as well. All spacecraft require a thermal management system to maintain a tolerable thermal environment for the spacecraft crew and/or equipment. The requirements for human rating and the specified controlled temperature range (approximately 275 K - 310 K) for crewed spacecraft are unique, and key design criteria stem from overall vehicle and operational/programatic considerations. These criteria include high reliability, low mass, minimal power requirements, low development and operational costs, and high confidence for mission success and safety. This section describes the four major subsystems for crewed spacecraft thermal management systems, and design considerations for each. Additionally, some examples of specialized or advanced thermal system technologies are presented

  10. Travel behavior, residential preference, and urban design : a multi-disciplinary national analysis

    Science.gov (United States)

    2011-01-01

    This report summarizes the findings of a national project to examine the travel behavior, social capital, health, and lifestyle preferences of residents of neotraditional developments (NTD) compared to more standard suburban developments. We compare ...

  11. Design Support System for Coloring Illustrations by Using the Colors Preferred by a User as Determined from the Hue Patterns of Illustrations Prepared by that User

    Science.gov (United States)

    Fukai, Hironobu; Mitsukura, Yasue

    We propose a new design support system that can color illustrations according to a person's color preferences that are determined on the basis of the color patterns of illustrations prepared by that person. Recently, many design tools for promoting free design have been developed. However, preferences for various colors differ depending on individual personality. Therefore, a system that can automatically color various designs on the basis of human preference is required. In this study, we propose an automatic modeling system that can be used to model illustrations. To verify the effectiveness of the proposed system, we simulate a coloring design experiment to determine the color patterns preferred by some subjects by using various design data. By using the design data, we determine each subjects preferred color pattern, and send feedback on these individual color patterns to the proposed system.

  12. Gravity Probe B spacecraft description

    International Nuclear Information System (INIS)

    Bennett, Norman R; Burns, Kevin; Katz, Russell; Kirschenbaum, Jon; Mason, Gary; Shehata, Shawky

    2015-01-01

    The Gravity Probe B spacecraft, developed, integrated, and tested by Lockheed Missiles and Space Company and later Lockheed Martin Corporation, consisted of structures, mechanisms, command and data handling, attitude and translation control, electrical power, thermal control, flight software, and communications. When integrated with the payload elements, the integrated system became the space vehicle. Key requirements shaping the design of the spacecraft were: (1) the tight mission timeline (17 months, 9 days of on-orbit operation), (2) precise attitude and translational control, (3) thermal protection of science hardware, (4) minimizing aerodynamic, magnetic, and eddy current effects, and (5) the need to provide a robust, low risk spacecraft. The spacecraft met all mission requirements, as demonstrated by dewar lifetime meeting specification, positive power and thermal margins, precision attitude control and drag-free performance, reliable communications, and the collection of more than 97% of the available science data. (paper)

  13. Modeling the fundamental characteristics and processes of the spacecraft functioning

    Science.gov (United States)

    Bazhenov, V. I.; Osin, M. I.; Zakharov, Y. V.

    1986-01-01

    The fundamental aspects of modeling of spacecraft characteristics by using computing means are considered. Particular attention is devoted to the design studies, the description of physical appearance of the spacecraft, and simulated modeling of spacecraft systems. The fundamental questions of organizing the on-the-ground spacecraft testing and the methods of mathematical modeling were presented.

  14. Trends in preference, programming and design of concert halls for symphonic music

    DEFF Research Database (Denmark)

    Gade, Anders Christian

    2008-01-01

    This paper discusses the evolution in taste regarding concert hall acoustics and how this can be reflected in the new halls being built today. The clients' and listener's preferences are not only based on listening in existing halls; but also on listening to reproduced music recorded with microph......This paper discusses the evolution in taste regarding concert hall acoustics and how this can be reflected in the new halls being built today. The clients' and listener's preferences are not only based on listening in existing halls; but also on listening to reproduced music recorded...

  15. Toward autonomous spacecraft

    Science.gov (United States)

    Fogel, L. J.; Calabrese, P. G.; Walsh, M. J.; Owens, A. J.

    1982-01-01

    Ways in which autonomous behavior of spacecraft can be extended to treat situations wherein a closed loop control by a human may not be appropriate or even possible are explored. Predictive models that minimize mean least squared error and arbitrary cost functions are discussed. A methodology for extracting cyclic components for an arbitrary environment with respect to usual and arbitrary criteria is developed. An approach to prediction and control based on evolutionary programming is outlined. A computer program capable of predicting time series is presented. A design of a control system for a robotic dense with partially unknown physical properties is presented.

  16. Design of a Carbon Fiber Composite Grid Structure for the GLAST Spacecraft Using a Novel Manufacturing Technique

    Energy Technology Data Exchange (ETDEWEB)

    Hicks, M

    2004-04-12

    The Gamma-Ray Large Area Space Telescope is an orbital observatory being planned as a joint DOE/NASA mission. The primary support of the instrument requires a grid structure which is very stiff, strong, light-weight, and thermally conductive. A carbon fiber composite grid design using a novel manufacture technique is proposed which meets or exceeds an aluminum design in all performance criteria and is economically competitive as well. Finite element analysis, confirmed by testing of a sample grid, is used to examine trade-offs for the materials and layups. Based on these analyses, recommendations are given for a viable design.

  17. Power Subsystem Design for Tiangong-1 Target Spacecraft%天宫一号目标飞行器电源分系统设计

    Institute of Scientific and Technical Information of China (English)

    陈启忠; 马季军; 王娜; 黄应春; 黄峥; 王振绪

    2011-01-01

    The sketch and main performances of the power subsystem of Tiangong-1 target spacecraft were introduced in this paper. The key technologies in domestic such as the bus with the voltage 100 V applied on low orbit spacecraft, large-scale nickel-metal hybrid batteries, triple-junction gallium arsenide solar cells and semi-rigid solar wings were given out. The main job of the high voltage device system establishing, the semi-rigid solar dynamics and space environment design and verification, the life time and reliability of the nickel-metal hybrid battery, and the reliability and safety of the high voltage power system were reviewed. The operation on orbit was given out. The research of the power subsystem of Tiangong-1 target spacecraft would establish the foundation for the China's next space technology.%介绍了天宫一号(TG1)目标飞行器电源分系统的组成和主要技术指标。分析了国内在低轨飞行器上采用100V高压母线、大批量使用国产氢镍电池、三结砷化镓太阳电池片和半刚性基板等关键技术。回顾了电源分系统研制过程中高电压元器件体系建立、半刚性帆板力学及空间环境设计与验证、氢镍电池在轨寿命和可靠性研究,以及高压电源系统可靠性及安全性研究等主要工作。给出了在轨运行情况。TG-1目标飞行器电源分系统的研制为我国后续空间技术的发展打下了基础。

  18. Attitude coordination for spacecraft formation with multiple communication delays

    Directory of Open Access Journals (Sweden)

    Guo Yaohua

    2015-04-01

    Full Text Available Communication delays are inherently present in information exchange between spacecraft and have an effect on the control performance of spacecraft formation. In this work, attitude coordination control of spacecraft formation is addressed, which is in the presence of multiple communication delays between spacecraft. Virtual system-based approach is utilized in case that a constant reference attitude is available to only a part of the spacecraft. The feedback from the virtual systems to the spacecraft formation is introduced to maintain the formation. Using backstepping control method, input torque of each spacecraft is designed such that the attitude of each spacecraft converges asymptotically to the states of its corresponding virtual system. Furthermore, the backstepping technique and the Lyapunov–Krasovskii method contribute to the control law design when the reference attitude is time-varying and can be obtained by each spacecraft. Finally, effectiveness of the proposed methodology is illustrated by the numerical simulations of a spacecraft formation.

  19. Benefits of Spacecraft Level Vibration Testing

    Science.gov (United States)

    Gordon, Scott; Kern, Dennis L.

    2015-01-01

    NASA-HDBK-7008 Spacecraft Level Dynamic Environments Testing discusses the approaches, benefits, dangers, and recommended practices for spacecraft level dynamic environments testing, including vibration testing. This paper discusses in additional detail the benefits and actual experiences of vibration testing spacecraft for NASA Goddard Space Flight Center (GSFC) and Jet Propulsion Laboratory (JPL) flight projects. JPL and GSFC have both similarities and differences in their spacecraft level vibration test approach: JPL uses a random vibration input and a frequency range usually starting at 5 Hz and extending to as high as 250 Hz. GSFC uses a sine sweep vibration input and a frequency range usually starting at 5 Hz and extending only to the limits of the coupled loads analysis (typically 50 to 60 Hz). However, both JPL and GSFC use force limiting to realistically notch spacecraft resonances and response (acceleration) limiting as necessary to protect spacecraft structure and hardware from exceeding design strength capabilities. Despite GSFC and JPL differences in spacecraft level vibration test approaches, both have uncovered a significant number of spacecraft design and workmanship anomalies in vibration tests. This paper will give an overview of JPL and GSFC spacecraft vibration testing approaches and provide a detailed description of spacecraft anomalies revealed.

  20. Engineering design, stress and thermal analysis, and documentation for SATS program

    Science.gov (United States)

    1973-01-01

    An in-depth analysis and mechanical design of the solar array stowage and deployment arrangements for use in Small Applications Technology Satellite spacecraft is presented. Alternate approaches for the major elements of work are developed and evaluated. Elements include array stowage and deployment arrangements, the spacecraft and array behavior in the spacecraft despin mode, and the design of the main hinge and segment hinge assemblies. Feasibility calculations are performed and the preferred approach is identified.

  1. Modelling the Preferences of Students for Alternative Assignment Designs Using the Discrete Choice Experiment Methodology

    Directory of Open Access Journals (Sweden)

    Brendan Kennelly

    2014-11-01

    Full Text Available This paper outlines how a discrete choice experiment (DCE can be used to learn more about how students are willing to trade off various features of assignments such as the nature and timing of feedback and the method used to submit assignments. A DCE identifies plausible levels of the key attributes of a good or service and then presents the respondent with alternative bundles of these attributes and their levels and asks the respondent to choose between particular bundles. We report results from a DCE we conducted with undergraduate business students regarding their preferences for assignment systems. We find that the most important features of assignments are how relevant the assignments are for exam preparation and the nature of the feedback that students receive. We also find that students generally prefer online to paper assignments. We argue that the DCE approach has a lot of potential in education research.

  2. Design and testing of a coaxial linear magnetic spring with integral linear motor. [for spacecraft energy storage

    Science.gov (United States)

    Patt, P. J.

    1985-01-01

    The design of a coaxial linear magnetic spring which incorporates a linear motor to control axial motion and overcome system damping is presented, and the results of static and dynamic tests are reported. The system has nominal stiffness 25,000 N/m and is designed to oscillate a 900-g component over a 4.6-mm stroke in a Stirling-cycle cryogenic refrigerator being developed for long-service (5-10-yr) space applications (Stolfi et al., 1983). Mosaics of 10 radially magnetized high-coercivity SmCO5 segments enclosed in Ti cans are employed, and the device is found to have quality factor 70-100, corresponding to energy-storage efficiency 91-94 percent. Drawings, diagrams, and graphs are provided.

  3. Spacecraft Orbit Design in the Circular Restricted Three-Body Problem Using Higher-Dimensional Poincare Maps

    Science.gov (United States)

    2013-12-01

    depiction of “space” is simplified (for pedagogical purposes) as a 2-D plane with a point in that planar “space” defined by its location in Cartesian...93 define a value associated with the color of each plotted dot. For pedagogical purposes, the color scale in this example is discretized to only...trajectory design in this 146 investigation, a “zoom” in color is often accompanied by a filtering based on the same color scale limits, thus

  4. Development of Design Standards and Guidelines for Electromagnetic Compatibility and Lightning Protection for Spacecraft Utilizing Composite Materials

    Science.gov (United States)

    Camp, Dennis W.

    1997-01-01

    This final report presents information concerning technical accomplishments by Tec-Masters, Inc. (TMI) for this contract effort. This effort included the accomplishment and/or submission by TMI of the following items: (1) Literature Survey Report, Electrical Properties of Non-Metallic Composites by Mr. Hugh W. Denny; (2) Interim Report, Composite Materials - Conductivity, Shielding Effectiveness, and Current Carrying Capability by Mr. Ross W. Evans; (3) Fault Current Test Plan by Mr. Ross W. Evans (4) Fault Current Test Procedure by Mr. Ross W. Evans (5) Test Report, Fault Current Through Graphite Filament Reinforced Plastic, NASA CR-4774, Marshall Space Flight Center, Alabama, September 1996, by Mr. Ross W. Evans; (6) Test Plan, Lightning Effects on Composite Materials by Mr. Ross W. Evans; (7) Test Report, Lightning Effects on Composite Materials, NASA CR-4783, Marshall Space Flight Center, Alabama, February 1997, by Mr. Ross W. Evans; (8) Design Guidelines for Shielding Effectiveness, Current Carrying Capability, and the Enhancement of Conductivity of Composite Materials, NASA CR-4784, Marshall Space Flight Center, Alabama, September 1996, by Mr. Ross W. Evans. These items are not attached but are considered to be a part of this final report. Efforts on two additional items were accomplished at no increase in cost to NASA/MSFC. These items consisted of updating the 'MSFC EMC Design and Interference Control Handbook,' and revising the 'Design Guidelines for Shielding Effectiveness, Current Carrying Capability, and the Enhancement of Conductivity of Composite Materials.'

  5. Conceptual Design of Simulation Models in an Early Development Phase of Lunar Spacecraft Simulator Using SMP2 Standard

    Science.gov (United States)

    Lee, Hoon Hee; Koo, Cheol Hea; Moon, Sung Tae; Han, Sang Hyuck; Ju, Gwang Hyeok

    2013-08-01

    The conceptual study for Korean lunar orbiter/lander prototype has been performed in Korea Aerospace Research Institute (KARI). Across diverse space programs around European countries, a variety of simulation application has been developed using SMP2 (Simulation Modelling Platform) standard related to portability and reuse of simulation models by various model users. KARI has not only first-hand experience of a development of SMP compatible simulation environment but also an ongoing study to apply the SMP2 development process of simulation model to a simulator development project for lunar missions. KARI has tried to extend the coverage of the development domain based on SMP2 standard across the whole simulation model life-cycle from software design to its validation through a lunar exploration project. Figure. 1 shows a snapshot from a visualization tool for the simulation of lunar lander motion. In reality, a demonstrator prototype on the right-hand side of image was made and tested in 2012. In an early phase of simulator development prior to a kick-off start in the near future, targeted hardware to be modelled has been investigated and indentified at the end of 2012. The architectural breakdown of the lunar simulator at system level was performed and the architecture with a hierarchical tree of models from the system to parts at lower level has been established. Finally, SMP Documents such as Catalogue, Assembly, Schedule and so on were converted using a XML(eXtensible Mark-up Language) converter. To obtain benefits of the suggested approaches and design mechanisms in SMP2 standard as far as possible, the object-oriented and component-based design concepts were strictly chosen throughout a whole model development process.

  6. SSTI- Lewis Spacecraft Nickel-Hydrogen Battery

    Science.gov (United States)

    Tobias, R. F.

    1997-01-01

    Topics considered include: NASA-Small Spacecraft Technology Initiative (SSTI) objectives, SSTI-Lewis overview, battery requirement, two cells Common Pressure Vessel (CPV) design summary, CPV electric performance, battery design summary, battery functional description, battery performance.

  7. A descriptive, cross-sectional study of medical student preferences for vodcast design, format and pedagogical approach.

    Science.gov (United States)

    Pettit, Robin K; Kinney, Marjorie; McCoy, Lise

    2017-05-19

    Vodcasts (video podcasts) are becoming increasingly popular in medical education. At A.T. Still University School of Osteopathic Medicine in Arizona (ATSU SOMA), vodcasts are an essential component of our blended learning environment, where year 2-4 students train in a contextual setting at community health centers across the U.S. Vodcasts are used far less frequently in our year 1 residential learning environment at the main campus in Arizona, but we are considering moving to significantly more interactive educational experiences with on-demand videos followed by in-class activities. The aim of this study was to determine stakeholder (i.e. medical student) preferences for vodcast design, format, and pedagogical strategies. The overall goal was to increase opportunities for students to learn with this modality. An interactive Qualtrics™ survey was administered to three cohorts of medical students. The survey generated quantitative and open-ended response data that addressed principles of vodcast instructional design and learning. Responses to survey items were analyzed for statistical significance using the independent samples t-test for interval data, the chi-square test for categorical data, and the Kruskal-Wallis test for ordinal data, using the post-hoc Bonferroni procedure to determine the appropriate α level. Responses to open-ended prompts were categorized using open- and axial-coding. The most highly valued vodcast attributes, considered essential by all three cohorts, were clear explanations, organization, conciseness, high-yield for medical board exams, and the ability to speed vodcasts up. The least helpful vodcast attributes for all three cohorts were music and objects moving on screen. The average preferred vodcast length for each cohort was 27-28 min. There were significant differences between the less experienced learners in the residential setting and the more mature learners in the blended learning environment regarding certain vodcast

  8. Architectural and Behavioral Systems Design Methodology and Analysis for Optimal Habitation in a Volume-Limited Spacecraft for Long Duration Flights

    Science.gov (United States)

    Kennedy, Kriss J.; Lewis, Ruthan; Toups, Larry; Howard, Robert; Whitmire, Alexandra; Smitherman, David; Howe, Scott

    2016-01-01

    As our human spaceflight missions change as we reach towards Mars, the risk of an adverse behavioral outcome increases, and requirements for crew health, safety, and performance, and the internal architecture, will need to change to accommodate unprecedented mission demands. Evidence shows that architectural arrangement and habitability elements impact behavior. Net habitable volume is the volume available to the crew after accounting for elements that decrease the functional volume of the spacecraft. Determination of minimum acceptable net habitable volume and associated architectural design elements, as mission duration and environment varies, is key to enabling, maintaining, andor enhancing human performance and psychological and behavioral health. Current NASA efforts to derive minimum acceptable net habitable volumes and study the interaction of covariates and stressors, such as sensory stimulation, communication, autonomy, and privacy, and application to internal architecture design layouts, attributes, and use of advanced accommodations will be presented. Furthermore, implications of crew adaptation to available volume as they transfer from Earth accommodations, to deep space travel, to planetary surface habitats, and return, will be discussed.

  9. Training for spacecraft technical analysts

    Science.gov (United States)

    Ayres, Thomas J.; Bryant, Larry

    1989-01-01

    Deep space missions such as Voyager rely upon a large team of expert analysts who monitor activity in the various engineering subsystems of the spacecraft and plan operations. Senior teammembers generally come from the spacecraft designers, and new analysts receive on-the-job training. Neither of these methods will suffice for the creation of a new team in the middle of a mission, which may be the situation during the Magellan mission. New approaches are recommended, including electronic documentation, explicit cognitive modeling, and coached practice with archived data.

  10. How Can Interdisciplinarity Of food, Design, Architecture, Engineering And Pedagogy Affect Children's Eating Habits And Food Preferences?

    DEFF Research Database (Denmark)

    Fisker, Anna Marie; Hermanssdottir, Sunna; Rasmussen, Mai

    Meals in day-care centers have for many children a crucial influence on the total experience of the stay. Research already suggests, that the meal situation should not be delimited to the nutritional meaning only, but has to be seen in a broad holistic perspective (Rasmussen and Smidt, 2001). In ...... and pedagogy can create solutions that positively affect eating habits and food preferences among children, and furthermore if this aspect can strengthen innovation in the food sector and create valuable solutions related to health benefits among children.......). In our research, regarding children’s eating habits and food preferences, we collaborated interdisciplinary, working holistically, involving appropriate disciplines, where knowledge from different fields was involved. The importance of working interdisciplinary in food innovation can be seen......, that affect children’s eating habits and food preferences. In order to make evidence in the field, an interdisciplinary team consisting of food specialists, designers, engineers, architects and pedagogues, created a carrot pavilion and appurtenant carrot activities. The aim was to influence the children...

  11. Dental students' preferences and performance in crown design: conventional wax-added versus CAD.

    Science.gov (United States)

    Douglas, R Duane; Hopp, Christa D; Augustin, Marcus A

    2014-12-01

    The purpose of this study was to evaluate dental students' perceptions of traditional waxing vs. computer-aided crown design and to determine the effectiveness of either technique through comparative grading of the final products. On one of twoidentical tooth preparations, second-year students at one dental school fabricated a wax pattern for a full contour crown; on the second tooth preparation, the same students designed and fabricated an all-ceramic crown using computer-aided design (CAD) and computer-aided manufacturing (CAM) technology. Projects were graded for occlusion and anatomic form by three faculty members. On completion of the projects, 100 percent of the students (n=50) completed an eight-question, five-point Likert scalesurvey, designed to assess their perceptions of and learning associated with the two design techniques. The average grades for the crown design projects were 78.3 (CAD) and 79.1 (wax design). The mean numbers of occlusal contacts were 3.8 (CAD) and 2.9(wax design), which was significantly higher for CAD (p=0.02). The survey results indicated that students enjoyed designing afull contour crown using CAD as compared to using conventional wax techniques and spent less time designing the crown using CAD. From a learning perspective, students felt that they learned more about position and the size/strength of occlusal contacts using CAD. However, students recognized that CAD technology has limits in terms of representing anatomic contours and excursive occlusion compared to conventional wax techniques. The results suggest that crown design using CAD could be considered as an adjunct to conventional wax-added techniques in preclinical fixed prosthodontic curricula.

  12. User Preferences for Web-Based Module Design Layout and Design Impact on Information Recall Considering Age

    Science.gov (United States)

    Pomales-García, Cristina; Rivera-Nivar, Mericia

    2015-01-01

    Research in design of Web-based modules should incorporate aging as an important factor given the diversity of the current workforce. This work aims to understand how Web-Based Learning modules can be designed to accommodate young (25-35 years) as well as older (55-65 years) users by: (1) identifying how information sources (instructor video,…

  13. Printed Spacecraft Separation System

    Energy Technology Data Exchange (ETDEWEB)

    Dehoff, Ryan R [ORNL; Holmans, Walter [Planetary Systems Corporation

    2016-10-01

    In this project Planetary Systems Corporation proposed utilizing additive manufacturing (3D printing) to manufacture a titanium spacecraft separation system for commercial and US government customers to realize a 90% reduction in the cost and energy. These savings were demonstrated via “printing-in” many of the parts and sub-assemblies into one part, thus greatly reducing the labor associated with design, procurement, assembly and calibration of mechanisms. Planetary Systems Corporation redesigned several of the components of the separation system based on additive manufacturing principles including geometric flexibility and the ability to fabricate complex designs, ability to combine multiple parts of an assembly into a single component, and the ability to optimize design for specific mechanical property targets. Shock absorption was specifically targeted and requirements were established to attenuate damage to the Lightband system from shock of initiation. Planetary Systems Corporation redesigned components based on these requirements and sent the designs to Oak Ridge National Laboratory to be printed. ORNL printed the parts using the Arcam electron beam melting technology based on the desire for the parts to be fabricated from Ti-6Al-4V based on the weight and mechanical performance of the material. A second set of components was fabricated from stainless steel material on the Renishaw laser powder bed technology due to the improved geometric accuracy, surface finish, and wear resistance of the material. Planetary Systems Corporation evaluated these components and determined that 3D printing is potentially a viable method for achieving significant cost and savings metrics.

  14. Xenia Mission: Spacecraft Design Concept

    Science.gov (United States)

    Hopkins, R. C.; Johnson, C. L.; Kouveliotou, C.; Jones, D.; Baysinger, M.; Bedsole, T.; Maples, C. C.; Benfield, P. J.; Turner, M.; Capizzo, P.; hide

    2009-01-01

    The proposed Xenia mission will, for the first time, chart the chemical and dynamical state of the majority of baryonic matter in the universe. using high-resolution spectroscopy, Xenia will collect essential information from major traces of the formation and evolution of structures from the early universe to the present time. The mission is based on innovative instrumental and observational approaches: observing with fast reaction gamma-ray bursts (GRBs) with a high spectral resolution. This enables the study of their (star-forming) environment from the dark to the local universe and the use of GRBs as backlight of large-scale cosmological structures, observing and surveying extended sources with high sensitivity using two wide field-of-view x-ray telescopes - one with a high angular resolution and the other with a high spectral resolution.

  15. Marketing Strategies Based on Consumer Preferences of Karnavas Mullberry Molasses with Protected Designation of Origin (PDO

    Directory of Open Access Journals (Sweden)

    Yavuz Topcu

    2017-07-01

    Full Text Available The aim of the study is to determine the integrated marketing tactic and strategies based on the main factors affecting the preferences and purchase patterns related to Karnavas Mullberry Molasses with PDO of the consumers dwelling in Erzurum. The main material of the study was provided by the primary data obtained from a survey conducted on 401 households residing in Erzurum during 2015, and consuming Karnavas Mullberry Molasses. Principal Component Analysis (PCA and Two-step Cluster Analysis were used to determine the main factors impacting on their purchase decisions, and then to segment homogenous clusters according to their purchase frequencies by taking into consideration the data, respectively. The results of the study indicated that the heavy and medium users who consume Karnavas Mullberry Molasses pointed out the necessity of the augmented and actual product image positioning at retail level under local individual brands considering the attributes of the holistic quality with PDO label and those of the sensory quality obtained from traditional production methods to contribute to rural development under the direct marketing approaches, respectively. On the other hand, the light users also focused on the increase of market penetration effect via promotion mix and the product positioning under the local branded actual product image implementing traditional production method and hedonic quality approaches. It could be applied the positioning and promotion strategies according to the consumers’ utility expectation and the product images, therefore, by considering their requirements and desires in each segment.

  16. Spacecraft Spin Test Facility

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Provides the capability to correct unbalances of spacecraft by using dynamic measurement techniques and static/coupled measurements to provide products of...

  17. OUTDOOR ENVIRONMENTS AT CRISIS SHELTERS: User Needs and Preferences with Respect to Design and Activities

    Directory of Open Access Journals (Sweden)

    Victoria L. Lygum

    2013-03-01

    Full Text Available The aim of this study was to identify implications for the design of outdoor environments at crisis shelters for women and children survivors of domestic violence. To address this aim, landscape analyses and interviews with staff were conducted at three Danish cases. The findings are presented in descriptions of the three cases in terms of the number of residents, context, building type and the characteristics of outdoor environments. Furthermore, a thematic content analysis of the interviews resulted in five categories that offer a nuanced insight into how the different types of outdoor environments support crisis shelter functions. The categories are: Protection against perpetrators of violence and helping residents to feel safe; Accessibility in the design, straightforward activities and staff guidance; Being outside and the positive distractions of nature; Space for all; Room to play and relieve children’s feelings. Finally, the findings were summarized to give an overview of implications for design.

  18. Spacecraft Cabin Particulate Monitor, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to design, build and test an optical extinction monitor for the detection of spacecraft cabin particulates. This monitor will be sensitive to particle...

  19. Consumer emotional response as a predictor of preferences: A case of hotel style design

    OpenAIRE

    Mukhamejanova, Zukhra; Korbo, Kristie L.

    2015-01-01

    Master's thesis in International hotel and tourism management As the hospitality industry grows, so does the number of consumers booking hotels online. These consumers choose hotels based on webpage information such as hotel pictures and other promotional media. Given the importance of visual stimuli displayed on hotel webpages, little research effort has been devoted to the guests’ emotional response to hotel design. The aim of this study is to measure consumer’s emotional responses an...

  20. Designing an Authorization System Based on Patient Privacy Preferences in Japan.

    Science.gov (United States)

    Morris, Kensuke; Yamamoto, Goshiro; Hiragi, Shusuke; Ohtera, Shosuke; Sakai, Michi; Sugiyama, Osamu; Okamoto, Kazuya; Nambu, Masayuki; Kuroda, Tomohiro

    2018-01-01

    High accessibility of Electronic Health Record systems can increase usability but creates simultaneously patients' anxieties about privacy issues. In order to reduce the privacy concerns, we focused on control and awareness, and designed an approach that can provide availability of patient's clinical data to doctors in two scenarios; (S1) direct control by the patient when they are conscious, (S2) control by a trusted representative when the patient is unconscious. In this paper, we show further analysis in a survey (n = 310, age range: 19-91) done to test the acceptability of our concept of a using a trusted representative and to further understand the concerns of Japanese citizens to improve our system design. These results in S1 suggest that patients concerned about control have a stronger inclination to also choose full awareness. We found also that patients tended to choose the same level of awareness for the representative as they did for themselves in S2. In addition, patients who chose awareness in S1 tended to choose the same for their representative in S2 and themselves after recovery from unconsciousness. We also discuss the significant differences found between the age-groups 20-39 and 60-79. We conclude that the system design of privacy aware EHR systems must be improved to consider patients who want to preserve their choice of control in the event they become unconscious but do not want to use a representative to maintain control.

  1. Airborne particulate matter in spacecraft

    Science.gov (United States)

    1988-01-01

    Acceptability limits and sampling and monitoring strategies for airborne particles in spacecraft were considered. Based on instances of eye and respiratory tract irritation reported by Shuttle flight crews, the following acceptability limits for airborne particles were recommended: for flights of 1 week or less duration (1 mg/cu m for particles less than 10 microns in aerodynamic diameter (AD) plus 1 mg/cu m for particles 10 to 100 microns in AD); and for flights greater than 1 week and up to 6 months in duration (0.2 mg/cu m for particles less than 10 microns in AD plus 0.2 mg/cu m for particles 10 to 100 microns in AD. These numerical limits were recommended to aid in spacecraft atmosphere design which should aim at particulate levels that are a low as reasonably achievable. Sampling of spacecraft atmospheres for particles should include size-fractionated samples of 0 to 10, 10 to 100, and greater than 100 micron particles for mass concentration measurement and elementary chemical analysis by nondestructive analysis techniques. Morphological and chemical analyses of single particles should also be made to aid in identifying airborne particulate sources. Air cleaning systems based on inertial collection principles and fine particle collection devices based on electrostatic precipitation and filtration should be considered for incorporation into spacecraft air circulation systems. It was also recommended that research be carried out in space in the areas of health effects and particle characterization.

  2. Spacecraft command and control using expert systems

    Science.gov (United States)

    Norcross, Scott; Grieser, William H.

    1994-01-01

    This paper describes a product called the Intelligent Mission Toolkit (IMT), which was created to meet the changing demands of the spacecraft command and control market. IMT is a command and control system built upon an expert system. Its primary functions are to send commands to the spacecraft and process telemetry data received from the spacecraft. It also controls the ground equipment used to support the system, such as encryption gear, and telemetry front-end equipment. Add-on modules allow IMT to control antennas and antenna interface equipment. The design philosophy for IMT is to utilize available commercial products wherever possible. IMT utilizes Gensym's G2 Real-time Expert System as the core of the system. G2 is responsible for overall system control, spacecraft commanding control, and spacecraft telemetry analysis and display. Other commercial products incorporated into IMT include the SYBASE relational database management system and Loral Test and Integration Systems' System 500 for telemetry front-end processing.

  3. Spacecraft Charge Monitor

    Science.gov (United States)

    Goembel, L.

    2003-12-01

    We are currently developing a flight prototype Spacecraft Charge Monitor (SCM) with support from NASA's Small Business Innovation Research (SBIR) program. The device will use a recently proposed high energy-resolution electron spectroscopic technique to determine spacecraft floating potential. The inspiration for the technique came from data collected by the Atmosphere Explorer (AE) satellites in the 1970s. The data available from the AE satellites indicate that the SCM may be able to determine spacecraft floating potential to within 0.1 V under certain conditions. Such accurate measurement of spacecraft charge could be used to correct biases in space plasma measurements. The device may also be able to measure spacecraft floating potential in the solar wind and in orbit around other planets.

  4. Autonomous spacecraft rendezvous and docking

    Science.gov (United States)

    Tietz, J. C.; Almand, B. J.

    A storyboard display is presented which summarizes work done recently in design and simulation of autonomous video rendezvous and docking systems for spacecraft. This display includes: photographs of the simulation hardware, plots of chase vehicle trajectories from simulations, pictures of the docking aid including image processing interpretations, and drawings of the control system strategy. Viewgraph-style sheets on the display bulletin board summarize the simulation objectives, benefits, special considerations, approach, and results.

  5. Social preferences

    DEFF Research Database (Denmark)

    Gulløv, Eva

    2014-01-01

    The focus of this article is social divisions among preschool children in daycare centers. Based on ethnographic fieldwork in three daycare centers in Denmark, the analysis concerns young children’s social preferences. The ethnographic material shows that despite an explicit political ambition...... of daycares as means for social and cultural integration, lines of division do exist amongst the children. Such divisions are established in the daily interactions of the daycare, but they also reflect those of the broader society. With a focus on children’s interactions and social preferences, the material...... indicates that children’s choices of playmates run along lines of ethnic and class divisions. The article will address this pattern and analyze its causes in order to understand why such lines of divisions are to be found in an institutional context designed to overcome social inequality and prevent social...

  6. Application of preference selection index method for decision making over the design stage of production system life cycle

    Directory of Open Access Journals (Sweden)

    Rajesh Attri

    2015-07-01

    Full Text Available The life cycle of production system shows the progress of production system from the inception to the termination of the system. During each stage, mainly in the design stage, certain strategic decisions have to be taken. These decisions are more complex as the decision makers have to assess a wide range of alternatives based on a set of conflicting criteria. As the decision making process is found to be unstructured, characterized by domain dependent knowledge, there is a need to apply an efficient multi-criteria decision making (MCDM tool to help the decision makers in making correct decisions. This paper explores the application of a novel MCDM method i.e. Preference selection index (PSI method to solve various decision-making problems that are generally encountered in the design stage of production system life cycle. To prove the potentiality, applicability and accuracy of PSI method in solving decision making problem during the design stage of production system life cycle, five examples are cited from the literature and are compared with the results obtained by the past researchers.

  7. Housing Stakeholder Preferences for the "Soft" Features of Sustainable and Healthy Housing Design in the UK.

    Science.gov (United States)

    Prochorskaite, Agne; Couch, Chris; Malys, Naglis; Maliene, Vida

    2016-01-07

    It is widely recognised that the quantity and sustainability of new homes in the UK need to increase. However, it is important that sustainable housing is regarded holistically, and not merely in environmental terms, and incorporates elements that enhance the quality of life, health and well-being of its users. This paper focuses on the "soft" features of sustainable housing, that is, the non-technological components of sustainable housing and neighbourhood design that can impact occupants' health and well-being. Aims of the study are to ascertain the relative level of importance that key housing stakeholders attach to these features and to investigate whether the opinions of housing users and housing providers are aligned with regards to their importance. An online survey was carried out to gauge the level of importance that the key stakeholders, such as housing users, local authorities, housing associations, and developers (n = 235), attach to these features. Results revealed that while suitable indoor space was the feature regarded as most important by all stakeholders, there were also a number of disparities in opinion between housing users and housing providers (and among the different types of providers). This implies a scope for initiatives to achieve a better alignment between housing users and providers.

  8. User Preferences and Design Recommendations for an mHealth App to Promote Cystic Fibrosis Self-Management.

    Science.gov (United States)

    Hilliard, Marisa E; Hahn, Amy; Ridge, Alana K; Eakin, Michelle N; Riekert, Kristin A

    2014-10-24

    mHealth apps hold potential to provide automated, tailored support for treatment adherence among individuals with chronic medical conditions. Yet relatively little empirical research has guided app development and end users are infrequently involved in designing the app features or functions that would best suit their needs. Self-management apps may be particularly useful for people with chronic conditions like cystic fibrosis (CF) that have complex, demanding regimens. The aim of this mixed-methods study was to involve individuals with CF in guiding the development of engaging, effective, user-friendly adherence promotion apps that meet their preferences and self-management needs. Adults with CF (n=16, aged 21-48 years, 50% male) provided quantitative data via a secure Web survey and qualitative data via semi-structured telephone interviews regarding previous experiences using apps in general and for health, and preferred and unwanted features of potential future apps to support CF self-management. Participants were smartphone users who reported sending or receiving text messages (93%, 14/15) or emails (80%, 12/15) on their smartphone or device every day, and 87% (13/15) said it would be somewhat or very hard to give up their smartphone. Approximately one-half (53%, 8/15) reported having health apps, all diet/weight-related, yet many reported that existing nutrition apps were not well-suited for CF management. Participants wanted apps to support CF self-management with characteristics such as having multiple rather than single functions (eg, simple alarms), being specific to CF, and minimizing user burden. Common themes for desired CF app features were having information at one's fingertips, automation of disease management activities such as pharmacy refills, integration with smartphones' technological capabilities, enhancing communication with health care team, and facilitating socialization within the CF community. Opinions were mixed regarding gamification and

  9. Worldwide Spacecraft Crew Hatch History

    Science.gov (United States)

    Johnson, Gary

    2009-01-01

    The JSC Flight Safety Office has developed this compilation of historical information on spacecraft crew hatches to assist the Safety Tech Authority in the evaluation and analysis of worldwide spacecraft crew hatch design and performance. The document is prepared by SAIC s Gary Johnson, former NASA JSC S&MA Associate Director for Technical. Mr. Johnson s previous experience brings expert knowledge to assess the relevancy of data presented. He has experience with six (6) of the NASA spacecraft programs that are covered in this document: Apollo; Skylab; Apollo Soyuz Test Project (ASTP), Space Shuttle, ISS and the Shuttle/Mir Program. Mr. Johnson is also intimately familiar with the JSC Design and Procedures Standard, JPR 8080.5, having been one of its original developers. The observations and findings are presented first by country and organized within each country section by program in chronological order of emergence. A host of reference sources used to augment the personal observations and comments of the author are named within the text and/or listed in the reference section of this document. Careful attention to the selection and inclusion of photos, drawings and diagrams is used to give visual association and clarity to the topic areas examined.

  10. Fractionated Spacecraft Architectures Seeding Study

    National Research Council Canada - National Science Library

    Mathieu, Charlotte; Weigel, Annalisa

    2006-01-01

    .... Models were developed from a customer-centric perspective to assess different fractionated spacecraft architectures relative to traditional spacecraft architectures using multi-attribute analysis...

  11. Spacecraft momentum control systems

    CERN Document Server

    Leve, Frederick A; Peck, Mason A

    2015-01-01

    The goal of this book is to serve both as a practical technical reference and a resource for gaining a fuller understanding of the state of the art of spacecraft momentum control systems, specifically looking at control moment gyroscopes (CMGs). As a result, the subject matter includes theory, technology, and systems engineering. The authors combine material on system-level architecture of spacecraft that feature momentum-control systems with material about the momentum-control hardware and software. This also encompasses material on the theoretical and algorithmic approaches to the control of space vehicles with CMGs. In essence, CMGs are the attitude-control actuators that make contemporary highly agile spacecraft possible. The rise of commercial Earth imaging, the advances in privately built spacecraft (including small satellites), and the growing popularity of the subject matter in academic circles over the past decade argues that now is the time for an in-depth treatment of the topic. CMGs are augmented ...

  12. Spacecraft Material Outgassing Data

    Data.gov (United States)

    National Aeronautics and Space Administration — This compilation of outgassing data of materials intended for spacecraft use were obtained at the Goddard Space Flight Center (GSFC), utilizing equipment developed...

  13. Spacecraft Fire Safety Demonstration

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of the Spacecraft Fire Safety Demonstration project is to develop and conduct large-scale fire safety experiments on an International Space Station...

  14. Quick spacecraft charging primer

    International Nuclear Information System (INIS)

    Larsen, Brian Arthur

    2014-01-01

    This is a presentation in PDF format which is a quick spacecraft charging primer, meant to be used for program training. It goes into detail about charging physics, RBSP examples, and how to identify charging.

  15. Deployable Brake for Spacecraft

    Science.gov (United States)

    Rausch, J. R.; Maloney, J. W.

    1987-01-01

    Aerodynamic shield that could be opened and closed proposed. Report presents concepts for deployable aerodynamic brake. Brake used by spacecraft returning from high orbit to low orbit around Earth. Spacecraft makes grazing passes through atmosphere to slow down by drag of brake. Brake flexible shield made of woven metal or ceramic withstanding high temperatures created by air friction. Stored until needed, then deployed by set of struts.

  16. Simulator Facility for Attitude Control and Energy Storage of Spacecraft

    National Research Council Canada - National Science Library

    Tsiotras, Panagiotis

    2002-01-01

    This report concerns a designed and built experimental facility that will allow the conduction of experiments for validating advanced attitude control algorithms for spacecraft in a weightless environment...

  17. A Reconfigurable Testbed Environment for Spacecraft Autonomy

    Science.gov (United States)

    Biesiadecki, Jeffrey; Jain, Abhinandan

    1996-01-01

    A key goal of NASA's New Millennium Program is the development of technology for increased spacecraft on-board autonomy. Achievement of this objective requires the development of a new class of ground-based automony testbeds that can enable the low-cost and rapid design, test, and integration of the spacecraft autonomy software. This paper describes the development of an Autonomy Testbed Environment (ATBE) for the NMP Deep Space I comet/asteroid rendezvous mission.

  18. Spacecraft Charging: Hazard Causes, Hazard Effects, Hazard Controls

    Science.gov (United States)

    Koontz, Steve.

    2018-01-01

    Spacecraft flight environments are characterized both by a wide range of space plasma conditions and by ionizing radiation (IR), solar ultraviolet and X-rays, magnetic fields, micrometeoroids, orbital debris, and other environmental factors, all of which can affect spacecraft performance. Dr. Steven Koontz's lecture will provide a solid foundation in the basic engineering physics of spacecraft charging and charging effects that can be applied to solving practical spacecraft and spacesuit engineering design, verification, and operations problems, with an emphasis on spacecraft operations in low-Earth orbit, Earth's magnetosphere, and cis-Lunar space.

  19. Internet Technology on Spacecraft

    Science.gov (United States)

    Rash, James; Parise, Ron; Hogie, Keith; Criscuolo, Ed; Langston, Jim; Powers, Edward I. (Technical Monitor)

    2000-01-01

    The Operating Missions as Nodes on the Internet (OMNI) project has shown that Internet technology works in space missions through a demonstration using the UoSAT-12 spacecraft. An Internet Protocol (IP) stack was installed on the orbiting UoSAT-12 spacecraft and tests were run to demonstrate Internet connectivity and measure performance. This also forms the basis for demonstrating subsequent scenarios. This approach provides capabilities heretofore either too expensive or simply not feasible such as reconfiguration on orbit. The OMNI project recognized the need to reduce the risk perceived by mission managers and did this with a multi-phase strategy. In the initial phase, the concepts were implemented in a prototype system that includes space similar components communicating over the TDRS (space network) and the terrestrial Internet. The demonstration system includes a simulated spacecraft with sample instruments. Over 25 demonstrations have been given to mission and project managers, National Aeronautics and Space Administration (NASA), Department of Defense (DoD), contractor technologists and other decisions makers, This initial phase reached a high point with an OMNI demonstration given from a booth at the Johnson Space Center (JSC) Inspection Day 99 exhibition. The proof to mission managers is provided during this second phase with year 2000 accomplishments: testing the use of Internet technologies onboard an actual spacecraft. This was done with a series of tests performed using the UoSAT-12 spacecraft. This spacecraft was reconfigured on orbit at very low cost. The total period between concept and the first tests was only 6 months! On board software was modified to add an IP stack to support basic IP communications. Also added was support for ping, traceroute and network timing protocol (NTP) tests. These tests show that basic Internet functionality can be used onboard spacecraft. The performance of data was measured to show no degradation from current

  20. Automated constraint checking of spacecraft command sequences

    Science.gov (United States)

    Horvath, Joan C.; Alkalaj, Leon J.; Schneider, Karl M.; Spitale, Joseph M.; Le, Dang

    1995-01-01

    Robotic spacecraft are controlled by onboard sets of commands called "sequences." Determining that sequences will have the desired effect on the spacecraft can be expensive in terms of both labor and computer coding time, with different particular costs for different types of spacecraft. Specification languages and appropriate user interface to the languages can be used to make the most effective use of engineering validation time. This paper describes one specification and verification environment ("SAVE") designed for validating that command sequences have not violated any flight rules. This SAVE system was subsequently adapted for flight use on the TOPEX/Poseidon spacecraft. The relationship of this work to rule-based artificial intelligence and to other specification techniques is discussed, as well as the issues that arise in the transfer of technology from a research prototype to a full flight system.

  1. Spacecraft Multiple Array Communication System Performance Analysis

    Science.gov (United States)

    Hwu, Shian U.; Desilva, Kanishka; Sham, Catherine C.

    2010-01-01

    The Communication Systems Simulation Laboratory (CSSL) at the NASA Johnson Space Center is tasked to perform spacecraft and ground network communication system simulations, design validation, and performance verification. The CSSL has developed simulation tools that model spacecraft communication systems and the space and ground environment in which the tools operate. In this paper, a spacecraft communication system with multiple arrays is simulated. Multiple array combined technique is used to increase the radio frequency coverage and data rate performance. The technique is to achieve phase coherence among the phased arrays to combine the signals at the targeting receiver constructively. There are many technical challenges in spacecraft integration with a high transmit power communication system. The array combining technique can improve the communication system data rate and coverage performances without increasing the system transmit power requirements. Example simulation results indicate significant performance improvement can be achieved with phase coherence implementation.

  2. The Effect of Design Modifications to the Typographical Layout of the New York State Elementary Science Learning Standards on User Preference and Process Time

    Science.gov (United States)

    Arnold, Jeffery E.

    2010-01-01

    The purpose of this study was to determine the effect of four different design layouts of the New York State elementary science learning standards on user processing time and preference. Three newly developed layouts contained the same information as the standards core curriculum. In this study, the layout of the core guide is referred to as Book.…

  3. Revamping Spacecraft Operational Intelligence

    Science.gov (United States)

    Hwang, Victor

    2012-01-01

    The EPOXI flight mission has been testing a new commercial system, Splunk, which employs data mining techniques to organize and present spacecraft telemetry data in a high-level manner. By abstracting away data-source specific details, Splunk unifies arbitrary data formats into one uniform system. This not only reduces the time and effort for retrieving relevant data, but it also increases operational visibility by allowing a spacecraft team to correlate data across many different sources. Splunk's scalable architecture coupled with its graphing modules also provide a solid toolset for generating data visualizations and building real-time applications such as browser-based telemetry displays.

  4. SHARP - Automated monitoring of spacecraft health and status

    Science.gov (United States)

    Atkinson, David J.; James, Mark L.; Martin, R. G.

    1990-01-01

    Briefly discussed here are the spacecraft and ground systems monitoring process at the Jet Propulsion Laboratory (JPL). Some of the difficulties associated with the existing technology used in mission operations are highlighted. A new automated system based on artificial intelligence technology is described which seeks to overcome many of these limitations. The system, called the Spacecraft Health Automated Reasoning Prototype (SHARP), is designed to automate health and status analysis for multi-mission spacecraft and ground data systems operations. The system has proved to be effective for detecting and analyzing potential spacecraft and ground systems problems by performing real-time analysis of spacecraft and ground data systems engineering telemetry. Telecommunications link analysis of the Voyager 2 spacecraft was the initial focus for evaluation of the system in real-time operations during the Voyager spacecraft encounter with Neptune in August 1989.

  5. SHARP: Automated monitoring of spacecraft health and status

    Science.gov (United States)

    Atkinson, David J.; James, Mark L.; Martin, R. Gaius

    1991-01-01

    Briefly discussed here are the spacecraft and ground systems monitoring process at the Jet Propulsion Laboratory (JPL). Some of the difficulties associated with the existing technology used in mission operations are highlighted. A new automated system based on artificial intelligence technology is described which seeks to overcome many of these limitations. The system, called the Spacecraft Health Automated Reasoning Prototype (SHARP), is designed to automate health and status analysis for multi-mission spacecraft and ground data systems operations. The system has proved to be effective for detecting and analyzing potential spacecraft and ground systems problems by performing real-time analysis of spacecraft and ground data systems engineering telemetry. Telecommunications link analysis of the Voyager 2 spacecraft was the initial focus for evaluation of the system in real-time operations during the Voyager spacecraft encounter with Neptune in August 1989.

  6. Microgravity Flammability Experiments for Spacecraft Fire Safety

    DEFF Research Database (Denmark)

    Legros, Guillaume; Minster, Olivier; Tóth, Balazs

    2012-01-01

    As fire behaviour in manned spacecraft still remains poorly understood, an international topical team has been created to design a validation experiment that has an unprecedented large scale for a microgravity flammability experiment. While the validation experiment is being designed for a re-sup...

  7. Intelligent spacecraft module

    Science.gov (United States)

    Oungrinis, Konstantinos-Alketas; Liapi, Marianthi; Kelesidi, Anna; Gargalis, Leonidas; Telo, Marinela; Ntzoufras, Sotiris; Paschidi, Mariana

    2014-12-01

    The paper presents the development of an on-going research project that focuses on a human-centered design approach to habitable spacecraft modules. It focuses on the technical requirements and proposes approaches on how to achieve a spatial arrangement of the interior that addresses sufficiently the functional, physiological and psychosocial needs of the people living and working in such confined spaces that entail long-term environmental threats to human health and performance. Since the research perspective examines the issue from a qualitative point of view, it is based on establishing specific relationships between the built environment and its users, targeting people's bodily and psychological comfort as a measure toward a successful mission. This research has two basic branches, one examining the context of the system's operation and behavior and the other in the direction of identifying, experimenting and formulating the environment that successfully performs according to the desired context. The latter aspect is researched upon the construction of a scaled-model on which we run series of tests to identify the materiality, the geometry and the electronic infrastructure required. Guided by the principles of sensponsive architecture, the ISM research project explores the application of the necessary spatial arrangement and behavior for a user-centered, functional interior where the appropriate intelligent systems are based upon the existing mechanical and chemical support ones featured on space today, and especially on the ISS. The problem is set according to the characteristics presented at the Mars500 project, regarding the living quarters of six crew-members, along with their hygiene, leisure and eating areas. Transformable design techniques introduce spatial economy, adjustable zoning and increased efficiency within the interior, securing at the same time precise spatial orientation and character at any given time. The sensponsive configuration is

  8. An Online Causal Inference Framework for Modeling and Designing Systems Involving User Preferences: A State-Space Approach

    Directory of Open Access Journals (Sweden)

    Ibrahim Delibalta

    2017-01-01

    Full Text Available We provide a causal inference framework to model the effects of machine learning algorithms on user preferences. We then use this mathematical model to prove that the overall system can be tuned to alter those preferences in a desired manner. A user can be an online shopper or a social media user, exposed to digital interventions produced by machine learning algorithms. A user preference can be anything from inclination towards a product to a political party affiliation. Our framework uses a state-space model to represent user preferences as latent system parameters which can only be observed indirectly via online user actions such as a purchase activity or social media status updates, shares, blogs, or tweets. Based on these observations, machine learning algorithms produce digital interventions such as targeted advertisements or tweets. We model the effects of these interventions through a causal feedback loop, which alters the corresponding preferences of the user. We then introduce algorithms in order to estimate and later tune the user preferences to a particular desired form. We demonstrate the effectiveness of our algorithms through experiments in different scenarios.

  9. Independent preferences

    DEFF Research Database (Denmark)

    Vind, Karl

    1991-01-01

    A simple mathematical result characterizing a subset of a product set is proved and used to obtain additive representations of preferences. The additivity consequences of independence assumptions are obtained for preferences which are not total or transitive. This means that most of the economic ...... theory based on additive preferences - expected utility, discounted utility - has been generalized to preferences which are not total or transitive. Other economic applications of the theorem are given...

  10. Radiation Effects on Spacecraft Structural Materials

    International Nuclear Information System (INIS)

    Wang, Jy-An J.; Ellis, Ronald J.; Hunter, Hamilton T.; Singleterry, Robert C. Jr.

    2002-01-01

    Research is being conducted to develop an integrated technology for the prediction of aging behavior for space structural materials during service. This research will utilize state-of-the-art radiation experimental apparatus and analysis, updated codes and databases, and integrated mechanical and radiation testing techniques to investigate the suitability of numerous current and potential spacecraft structural materials. Also included are the effects on structural materials in surface modules and planetary landing craft, with or without fission power supplies. Spacecraft structural materials would also be in hostile radiation environments on the surface of the moon and planets without appreciable atmospheres and moons around planets with large intense magnetic and radiation fields (such as the Jovian moons). The effects of extreme temperature cycles in such locations compounds the effects of radiation on structural materials. This paper describes the integrated methodology in detail and shows that it will provide a significant technological advance for designing advanced spacecraft. This methodology will also allow for the development of advanced spacecraft materials through the understanding of the underlying mechanisms of material degradation in the space radiation environment. Thus, this technology holds a promise for revolutionary advances in material damage prediction and protection of space structural components as, for example, in the development of guidelines for managing surveillance programs regarding the integrity of spacecraft components, and the safety of the aging spacecraft. (authors)

  11. Collaborating With Parents of Children With Chronic Conditions and Professionals to Design, Develop and Pre-pilot PLAnT (the Parent Learning Needs and Preferences Assessment Tool).

    Science.gov (United States)

    Nightingale, Ruth; Wirz, Lucy; Cook, Wendy; Swallow, Veronica

    This study aimed to design, develop and pre-pilot an assessment tool (PLAnT) to identify parents' learning needs and preferences when carrying out home-based clinical care for their child with a chronic condition. A mixed methods, two-phased design was used. Phase 1: a total of 10 parents/carers and 13 professionals from six UK's children's kidney units participated in qualitative interviews. Interview data were used to develop the PLAnT. Eight of these participants subsequently took part in an online survey to refine the PLAnT. Phase 2: thirteen parents were paired with one of nine professionals to undertake a pre-pilot evaluation of PLAnT. Data were analyzed using the Framework approach. A key emergent theme identifying parents' learning needs and preferences was identified. The importance of professionals being aware of parents' learning needs and preferences was recognised. Participants discussed how parents' learning needs and preferences should be identified, including: the purpose for doing this, the process for doing this, and what would the outcome be of identifying parents' needs. The evidence suggests that asking parents directly about their learning needs and preferences may be the most reliable way for professionals to ascertain how to support individual parents' learning when sharing management of their child's chronic condition. With the increasing emphasis on parent-professional shared management of childhood chronic conditions, professionals can be guided by PLAnT in their assessment of parents' learning needs and preferences, based on identified barriers and facilitators to parental learning. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Managed ventricular pacing vs. conventional dual-chamber pacing for elective replacements: the PreFER MVP study: clinical background, rationale, and design.

    Science.gov (United States)

    Quesada, Aurelio; Botto, Gianluca; Erdogan, Ali; Kozak, Milan; Lercher, Peter; Nielsen, Jens Cosedis; Piot, Olivier; Ricci, Renato; Weiss, Christian; Becker, Daniel; Wetzels, Gwenn; De Roy, Luc

    2008-03-01

    Several clinical studies have shown that, in patients with intact atrioventricular (AV) conduction, unnecessary chronic right ventricular (RV) pacing can be detrimental. The managed ventricular pacing (MVP) algorithm is designed to give preference to spontaneous AV conduction, thus minimizing RV pacing. The clinical outcomes of MVP are being studied in several ongoing trials in patients undergoing a first device implantation, but it is unknown to what extent MVP is beneficial in patients with a history of ventricular pacing. The purpose of the Prefer for Elective Replacement MVP (PreFER MVP) study is to assess the superiority of the MVP algorithm to conventional pacemaker and implantable cardioverter-defibrillator programming in terms of freedom from hospitalization for cardiovascular causes in a population of patients exposed to long periods of ventricular pacing. PreFER MVP is a prospective, 1:1 parallel, randomized (MVP ON/MVP OFF), single-blinded multi-centre trial. The study population consists of patients with more than 40% ventricular pacing documented with their previous device. Approximately, 600 patients will be randomized and followed for at least 24 months. The primary endpoint comprises cardiovascular hospitalization. The PreFER MVP trial is the first large prospective randomized clinical trial evaluating the effect of MVP in patients with a history of RV pacing.

  13. The spacecraft encounters of Comet Halley

    Science.gov (United States)

    Asoka Mendis, D.; Tsurutani, Bruce T.

    1986-01-01

    The characteristics of the Comet Halley spacecraft 'fleet' (VEGA 1 and VEGA 2, Giotto, Suisei, and Sakigake) are presented. The major aims of these missions were (1) to discover and characterize the nucleus, (2) to characterize the atmosphere and ionosphere, (3) to characterize the dust, and (4) to characterize the nature of the large-scale comet-solar wind interaction. While the VEGA and Giotto missions were designed to study all four areas, Suisei addressed the second and fourth. Sakigake was designed to study the solar wind conditions upstream of the comet. It is noted that NASA's Deep Space Network played an important role in spacecraft tracking.

  14. Men's Preferences for Physical Activity Interventions: An Exploratory Study Using a Factorial Survey Design Created With R Software.

    Science.gov (United States)

    Chatfield, Sheryl L; Gamble, Abigail; Hallam, Jeffrey S

    2018-03-01

    Effective exercise interventions are needed to improve quality of life and decrease the impact of chronic disease. Researchers suggest males have been underrepresented in exercise intervention studies, resulting in less understanding of their exercise practices. Findings from preference survey methods suggest reasonable association between preference and behavior. The purpose of the research described in this article was to use factorial survey, a preference method, to identify the characteristics of exercise interventions most likely to appeal to male participants, so preferences might be incorporated into future intervention research. The research was guided by the framework of Bandura's social cognitive theory, such that variations in individual, environmental, and behavioral factors were incorporated into vignettes. Participants included 53 adult male nonadministrative staff and contract employees at a public university in the Southeastern United States, who each scored 8 vignettes resulting in 423 observations. Multilevel models were used to assess the influence of the factors. Participants scored vignettes that included exercising with a single partner, playing basketball, and exercising in the evening higher than vignettes with other options. Qualitative analysis of an open response item identified additional alternatives in group size, participant desire for coaching support, and interest in programs that incorporate a range of activity alternatives. Findings from this research were consistent with elements of social cognitive theory as applied to health promotion. Factorial surveys potentially provide a resource effective means of identifying participants' preferences for use when planning interventions. The addition of a single qualitative item helped clarify and expand findings from statistical analysis.

  15. Hybrid spacecraft attitude control system

    Directory of Open Access Journals (Sweden)

    Renuganth Varatharajoo

    2016-02-01

    Full Text Available The hybrid subsystem design could be an attractive approach for futurespacecraft to cope with their demands. The idea of combining theconventional Attitude Control System and the Electrical Power System ispresented in this article. The Combined Energy and Attitude ControlSystem (CEACS consisting of a double counter rotating flywheel assemblyis investigated for small satellites in this article. Another hybrid systemincorporating the conventional Attitude Control System into the ThermalControl System forming the Combined Attitude and Thermal ControlSystem (CATCS consisting of a "fluid wheel" and permanent magnets isalso investigated for small satellites herein. The governing equationsdescribing both these novel hybrid subsystems are presented and theironboard architectures are numerically tested. Both the investigated novelhybrid spacecraft subsystems comply with the reference missionrequirements.The hybrid subsystem design could be an attractive approach for futurespacecraft to cope with their demands. The idea of combining theconventional Attitude Control System and the Electrical Power System ispresented in this article. The Combined Energy and Attitude ControlSystem (CEACS consisting of a double counter rotating flywheel assemblyis investigated for small satellites in this article. Another hybrid systemincorporating the conventional Attitude Control System into the ThermalControl System forming the Combined Attitude and Thermal ControlSystem (CATCS consisting of a "fluid wheel" and permanent magnets isalso investigated for small satellites herein. The governing equationsdescribing both these novel hybrid subsystems are presented and theironboard architectures are numerically tested. Both the investigated novelhybrid spacecraft subsystems comply with the reference missionrequirements.

  16. Large-Scale Spacecraft Fire Safety Tests

    Science.gov (United States)

    Urban, David; Ruff, Gary A.; Ferkul, Paul V.; Olson, Sandra; Fernandez-Pello, A. Carlos; T'ien, James S.; Torero, Jose L.; Cowlard, Adam J.; Rouvreau, Sebastien; Minster, Olivier; hide

    2014-01-01

    An international collaborative program is underway to address open issues in spacecraft fire safety. Because of limited access to long-term low-gravity conditions and the small volume generally allotted for these experiments, there have been relatively few experiments that directly study spacecraft fire safety under low-gravity conditions. Furthermore, none of these experiments have studied sample sizes and environment conditions typical of those expected in a spacecraft fire. The major constraint has been the size of the sample, with prior experiments limited to samples of the order of 10 cm in length and width or smaller. This lack of experimental data forces spacecraft designers to base their designs and safety precautions on 1-g understanding of flame spread, fire detection, and suppression. However, low-gravity combustion research has demonstrated substantial differences in flame behavior in low-gravity. This, combined with the differences caused by the confined spacecraft environment, necessitates practical scale spacecraft fire safety research to mitigate risks for future space missions. To address this issue, a large-scale spacecraft fire experiment is under development by NASA and an international team of investigators. This poster presents the objectives, status, and concept of this collaborative international project (Saffire). The project plan is to conduct fire safety experiments on three sequential flights of an unmanned ISS re-supply spacecraft (the Orbital Cygnus vehicle) after they have completed their delivery of cargo to the ISS and have begun their return journeys to earth. On two flights (Saffire-1 and Saffire-3), the experiment will consist of a flame spread test involving a meter-scale sample ignited in the pressurized volume of the spacecraft and allowed to burn to completion while measurements are made. On one of the flights (Saffire-2), 9 smaller (5 x 30 cm) samples will be tested to evaluate NASAs material flammability screening tests

  17. Design of systemic autonomous safety for Tiangong-I target spacecraft%“天宫一号”,目标飞行器系统级自主安全设计

    Institute of Scientific and Technical Information of China (English)

    李智勇

    2011-01-01

    为确保载人飞行器在长期飞行中的设备安全以及短期飞行中航天员的安全,需要从系统层面进行自主安全设计,使航天器在出现地面无法快速反应的故障时能够启动安全模式进行自我保护.文章以能源安全设计为主对“天宫一号”目标飞行器系统级自主安全设计进行了论述,总结了设计经验,对后续型号的设计提出了建议.%In space flights, the safety of hardware during a long-time flight and that of astronaut during a short-time flight are important issues in the implementation of the mission goal. The capability of independent safety control should be designed for spacecraft in the system level against major faults beyond instant ground responses. This paper discusses the system design of autonomous safety for manned spacecraft, with primary concern on the power system. Some engineering practices and suggestions are summarized for further studies.

  18. Developing Sustainable Spacecraft Water Management Systems

    Science.gov (United States)

    Thomas, Evan A.; Klaus, David M.

    2009-01-01

    It is well recognized that water handling systems used in a spacecraft are prone to failure caused by biofouling and mineral scaling, which can clog mechanical systems and degrade the performance of capillary-based technologies. Long duration spaceflight applications, such as extended stays at a Lunar Outpost or during a Mars transit mission, will increasingly benefit from hardware that is generally more robust and operationally sustainable overtime. This paper presents potential design and testing considerations for improving the reliability of water handling technologies for exploration spacecraft. Our application of interest is to devise a spacecraft wastewater management system wherein fouling can be accommodated by design attributes of the management hardware, rather than implementing some means of preventing its occurrence.

  19. A Sustainable Spacecraft Component Database Solution, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Numerous spacecraft component databases have been developed to support NASA, DoD, and contractor design centers and design tools. Despite the clear utility of...

  20. How can interdisciplinarity of food, design, architecture and pedagogy affect children’s eating habits and food preferences?

    DEFF Research Database (Denmark)

    Fisker, Anna Marie; Hermanssdottir, Sunna; Rasmussen, Mai

    2012-01-01

    Abstract for the International Conference on Designing Food and Designing for Food 2012, London June 28-29, 2012......Abstract for the International Conference on Designing Food and Designing for Food 2012, London June 28-29, 2012...

  1. REQUIREMENTS FOR IMAGE QUALITY OF EMERGENCY SPACECRAFTS

    Directory of Open Access Journals (Sweden)

    A. I. Altukhov

    2015-05-01

    Full Text Available The paper deals with the method for formation of quality requirements to the images of emergency spacecrafts. The images are obtained by means of remote sensing of near-earth space orbital deployment in the visible range. of electromagnetic radiation. The method is based on a joint taking into account conditions of space survey, characteristics of surveillance equipment, main design features of the observed spacecrafts and orbital inspection tasks. Method. Quality score is the predicted linear resolution image that gives the possibility to create a complete view of pictorial properties of the space image obtained by electro-optical system from the observing satellite. Formulation of requirements to the numerical value of this indicator is proposed to perform based on the properties of remote sensing system, forming images in the conditions of outer space, and the properties of the observed emergency spacecraft: dimensions, platform construction of the satellite, on-board equipment placement. For method implementation the authors have developed a predictive model of requirements to a linear resolution for images of emergency spacecrafts, making it possible to select the intervals of space shooting and get the satellite images required for quality interpretation. Main results. To verify the proposed model functionality we have carried out calculations of the numerical values for the linear resolution of the image, ensuring the successful task of determining the gross structural damage of the spacecrafts and identifying changes in their spatial orientation. As input data were used with dimensions and geometric primitives corresponding to the shape of deemed inspected spacecrafts: Resurs-P", "Canopus-B", "Electro-L". Numerical values of the linear resolution images have been obtained, ensuring the successful task solution for determining the gross structural damage of spacecrafts.

  2. Rotational Motion Control of a Spacecraft

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Kulczycki, P.

    2001-01-01

    The paper adopts the energy shaping method to control of rotational motion. A global representation of the rigid body motion is given in the canonical form by a quaternion and its conjugate momenta. A general method for motion control on a cotangent bundle to the 3-sphere is suggested. The design...... algorithm is validated for three-axis spacecraft attitude control...

  3. Rotational motion control of a spacecraft

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Kulczycki, P.

    2003-01-01

    The paper adopts the energy shaping method to control of rotational motion. A global representation of the rigid body motion is given in the canonical form by a quaternion and its conjugate momenta. A general method for motion control on a cotangent bundle to the 3-sphere is suggested. The design...... algorithm is validated for three-axis spacecraft attitude control. Udgivelsesdato: APR...

  4. Spacecraft Attitude Control in Hamiltonian Framework

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    2000-01-01

    The objective of this paper is to give a design scheme for attitude control algorithms of a generic spacecraft. Along with the system model formulated in the Hamilton's canonical form the algorithm uses information about a required potential energy and a dissipative term. The control action...

  5. Application of Space Environmental Observations to Spacecraft Pre-Launch Engineering and Spacecraft Operations

    Science.gov (United States)

    Barth, Janet L.; Xapsos, Michael

    2008-01-01

    This presentation focuses on the effects of the space environment on spacecraft systems and applying this knowledge to spacecraft pre-launch engineering and operations. Particle radiation, neutral gas particles, ultraviolet and x-rays, as well as micrometeoroids and orbital debris in the space environment have various effects on spacecraft systems, including degradation of microelectronic and optical components, physical damage, orbital decay, biasing of instrument readings, and system shutdowns. Space climate and weather must be considered during the mission life cycle (mission concept, mission planning, systems design, and launch and operations) to minimize and manage risk to both the spacecraft and its systems. A space environment model for use in the mission life cycle is presented.

  6. Operational Philosophy Concerning Manned Spacecraft Cabin Leaks

    Science.gov (United States)

    DeSimpelaere, Edward

    2011-01-01

    The last thirty years have seen the Space Shuttle as the prime United States spacecraft for manned spaceflight missions. Many lessons have been learned about spacecraft design and operation throughout these years. Over the next few decades, a large increase of manned spaceflight in the commercial sector is expected. This will result in the exposure of commercial crews and passengers to many of the same risks crews of the Space Shuttle have encountered. One of the more dire situations that can be encountered is the loss of pressure in the habitable volume of the spacecraft during on orbit operations. This is referred to as a cabin leak. This paper seeks to establish a general cabin leak response philosophy with the intent of educating future spacecraft designers and operators. After establishing a relative definition for a cabin leak, the paper covers general descriptions of detection equipment, detection methods, and general operational methods for management of a cabin leak. Subsequently, all these items are addressed from the perspective of the Space Shuttle Program, as this will be of the most value to future spacecraft due to similar operating profiles. Emphasis here is placed upon why and how these methods and philosophies have evolved to meet the Space Shuttle s needs. This includes the core ideas of: considerations of maintaining higher cabin pressures vs. lower cabin pressures, the pros and cons of a system designed to feed the leak with gas from pressurized tanks vs. using pressure suits to protect against lower cabin pressures, timeline and consumables constraints, re-entry considerations with leaks of unknown origin, and the impact the International Space Station (ISS) has had to the standard Space Shuttle cabin leak response philosophy. This last item in itself includes: procedural management differences, hardware considerations, additional capabilities due to the presence of the ISS and its resource, and ISS docking/undocking considerations with a

  7. Robust Parametric Control of Spacecraft Rendezvous

    Directory of Open Access Journals (Sweden)

    Dake Gu

    2014-01-01

    Full Text Available This paper proposes a method to design the robust parametric control for autonomous rendezvous of spacecrafts with the inertial information with uncertainty. We consider model uncertainty of traditional C-W equation to formulate the dynamic model of the relative motion. Based on eigenstructure assignment and model reference theory, a concise control law for spacecraft rendezvous is proposed which could be fixed through solving an optimization problem. The cost function considers the stabilization of the system and other performances. Simulation results illustrate the robustness and effectiveness of the proposed control.

  8. A Randomized Crossover Design to Assess Learning Impact and Student Preference for Active and Passive Online Learning Modules.

    Science.gov (United States)

    Prunuske, Amy J; Henn, Lisa; Brearley, Ann M; Prunuske, Jacob

    Medical education increasingly involves online learning experiences to facilitate the standardization of curriculum across time and space. In class, delivering material by lecture is less effective at promoting student learning than engaging students in active learning experience and it is unclear whether this difference also exists online. We sought to evaluate medical student preferences for online lecture or online active learning formats and the impact of format on short- and long-term learning gains. Students participated online in either lecture or constructivist learning activities in a first year neurologic sciences course at a US medical school. In 2012, students selected which format to complete and in 2013, students were randomly assigned in a crossover fashion to the modules. In the first iteration, students strongly preferred the lecture modules and valued being told "what they need to know" rather than figuring it out independently. In the crossover iteration, learning gains and knowledge retention were found to be equivalent regardless of format, and students uniformly demonstrated a strong preference for the lecture format, which also on average took less time to complete. When given a choice for online modules, students prefer passive lecture rather than completing constructivist activities, and in the time-limited environment of medical school, this choice results in similar performance on multiple-choice examinations with less time invested. Instructors need to look more carefully at whether assessments and learning strategies are helping students to obtain self-directed learning skills and to consider strategies to help students learn to value active learning in an online environment.

  9. A Comparison of Learning Technologies for Teaching Spacecraft Software Development

    Science.gov (United States)

    Straub, Jeremy

    2014-01-01

    The development of software for spacecraft represents a particular challenge and is, in many ways, a worst case scenario from a design perspective. Spacecraft software must be "bulletproof" and operate for extended periods of time without user intervention. If the software fails, it cannot be manually serviced. Software failure may…

  10. Quantifying parental preferences for interventions designed to improve home food preparation and home food environments during early childhood.

    Science.gov (United States)

    Virudachalam, Senbagam; Chung, Paul J; Faerber, Jennifer A; Pian, Timothy M; Thomas, Karen; Feudtner, Chris

    2016-03-01

    Though preparing healthy food at home is a critical health promotion habit, few interventions have aimed to improve parental cooking skills and behaviors. We sought to understand parents' preferences and priorities regarding interventions to improve home food preparation practices and home food environments during early childhood. We administered a discrete choice experiment using maximum difference scaling. Eighty English-speaking parents of healthy 1-4 year-old children rated the relative importance of potential attributes of interventions to improve home food preparation practices and home food environments. We performed latent class analysis to identify subgroups of parents with similar preferences and tested for differences between the subgroups. Participants were mostly white or black 21-45 year-old women whose prevalence of overweight/obesity mirrored the general population. Latent class analysis revealed three distinct groups of parental preferences for intervention content: a healthy cooking group, focused on nutrition and cooking healthier food; a child persuasion group, focused on convincing toddlers to eat home-cooked food; and a creative cooking group, focused on cooking without recipes, meal planning, and time-saving strategies. Younger, lower income, 1-parent households comprised the healthy cooking group, while older, higher income, 2-parent households comprised the creative cooking group (p cooked dinner regularly, unlike the other two groups (p food preparation practices. Such interventions are important for creating healthier home food environments and preventing obesity starting from early childhood. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Robust Spacecraft Component Detection in Point Clouds

    Directory of Open Access Journals (Sweden)

    Quanmao Wei

    2018-03-01

    Full Text Available Automatic component detection of spacecraft can assist in on-orbit operation and space situational awareness. Spacecraft are generally composed of solar panels and cuboidal or cylindrical modules. These components can be simply represented by geometric primitives like plane, cuboid and cylinder. Based on this prior, we propose a robust automatic detection scheme to automatically detect such basic components of spacecraft in three-dimensional (3D point clouds. In the proposed scheme, cylinders are first detected in the iteration of the energy-based geometric model fitting and cylinder parameter estimation. Then, planes are detected by Hough transform and further described as bounded patches with their minimum bounding rectangles. Finally, the cuboids are detected with pair-wise geometry relations from the detected patches. After successive detection of cylinders, planar patches and cuboids, a mid-level geometry representation of the spacecraft can be delivered. We tested the proposed component detection scheme on spacecraft 3D point clouds synthesized by computer-aided design (CAD models and those recovered by image-based reconstruction, respectively. Experimental results illustrate that the proposed scheme can detect the basic geometric components effectively and has fine robustness against noise and point distribution density.

  12. Robust Spacecraft Component Detection in Point Clouds.

    Science.gov (United States)

    Wei, Quanmao; Jiang, Zhiguo; Zhang, Haopeng

    2018-03-21

    Automatic component detection of spacecraft can assist in on-orbit operation and space situational awareness. Spacecraft are generally composed of solar panels and cuboidal or cylindrical modules. These components can be simply represented by geometric primitives like plane, cuboid and cylinder. Based on this prior, we propose a robust automatic detection scheme to automatically detect such basic components of spacecraft in three-dimensional (3D) point clouds. In the proposed scheme, cylinders are first detected in the iteration of the energy-based geometric model fitting and cylinder parameter estimation. Then, planes are detected by Hough transform and further described as bounded patches with their minimum bounding rectangles. Finally, the cuboids are detected with pair-wise geometry relations from the detected patches. After successive detection of cylinders, planar patches and cuboids, a mid-level geometry representation of the spacecraft can be delivered. We tested the proposed component detection scheme on spacecraft 3D point clouds synthesized by computer-aided design (CAD) models and those recovered by image-based reconstruction, respectively. Experimental results illustrate that the proposed scheme can detect the basic geometric components effectively and has fine robustness against noise and point distribution density.

  13. Spacecraft exploration of asteroids

    International Nuclear Information System (INIS)

    Veverka, J.; Langevin, Y.; Farquhar, R.; Fulchignoni, M.

    1989-01-01

    After two decades of spacecraft exploration, we still await the first direct investigation of an asteroid. This paper describes how a growing international interest in the solar system's more primitive bodies should remedy this. Plans are under way in Europe for a dedicated asteroid mission (Vesta) which will include multiple flybys with in situ penetrator studies. Possible targets include 4 Vesta, 8 Flora and 46 Hestia; launch its scheduled for 1994 or 1996. In the United States, NASA plans include flybys of asteroids en route to outer solar system targets

  14. Spacecraft rendezvous and docking

    DEFF Research Database (Denmark)

    Jørgensen, John Leif

    1999-01-01

    The phenomenons and problems encountered when a rendezvous manoeuvre, and possible docking, of two spacecrafts has to be performed, have been the topic for numerous studies, and, details of a variety of scenarios has been analysed. So far, all solutions that has been brought into realization has...... been based entirely on direct human supervision and control. This paper describes a vision-based system and methodology, that autonomously generates accurate guidance information that may assist a human operator in performing the tasks associated with both the rendezvous and docking navigation...

  15. What's New is What's Old: Use of Bode's Integral Theorem (circa 1945) to Provide Insight for 21st Century Spacecraft Attitude Control System Design Tuning

    Science.gov (United States)

    Ruth, Mike; Lebsock, Ken; Dennehy, Neil

    2010-01-01

    This paper revisits the Bode integral theorem, first described in 1945 for feedback amplifier design, in the context of modern satellite Attitude Control System (ACS) design tasks. Use of Bode's Integral clarifies in an elegant way the connection between open-loop stability margins and closed-loop bandwidth. More importantly it shows that there is a very strong tradeoff between disturbance rejection below the satellite controller design bandwidth, and disturbance amplification in the 'penalty region' just above the design bandwidth. This information has been successfully used to re-tune the control designs for several NASA science-mission satellites. The Appendix of this paper contains a complete summary of the relevant integral conservation theorems for stable, unstable, and non-minimum- phase plants.

  16. Automating Trend Analysis for Spacecraft Constellations

    Science.gov (United States)

    Davis, George; Cooter, Miranda; Updike, Clark; Carey, Everett; Mackey, Jennifer; Rykowski, Timothy; Powers, Edward I. (Technical Monitor)

    2001-01-01

    missions such as DRACO with the intent that mission operations costs be significantly reduced. The goal of the Constellation Spacecraft Trend Analysis Toolkit (CSTAT) project is to serve as the pathfinder for a fully automated trending system to support spacecraft constellations. The development approach to be taken is evolutionary. In the first year of the project, the intent is to significantly advance the state of the art in current trending systems through improved functionality and increased automation. In the second year, the intent is to add an expert system shell, likely through the adaptation of an existing commercial-off-the-shelf (COTS) or government-off-the-shelf (GOTS) tool to implement some level of the trending intelligence that humans currently provide in manual operations. In the third year, the intent is to infuse the resulting technology into a near-term constellation or formation-flying mission to test it and gain experience in automated trending. The lessons learned from the real missions operations experience will then be used to improve the system, and to ultimately incorporate it into a fully autonomous, closed-loop mission operations system that is truly capable of supporting large constellations. In this paper, the process of automating trend analysis for spacecraft constellations will be addressed. First, the results of a survey on automation in spacecraft mission operations in general, and in trending systems in particular will be presented to provide an overview of the current state of the art. Next, a rule-based model for implementing intelligent spacecraft subsystem trending will be then presented, followed by a survey of existing COTS/GOTS tools that could be adapted for implementing such a model. The baseline design and architecture of the CSTAT system will be presented. Finally, some results obtained from initial software tests and demonstrations will be presented.

  17. Low cost spacecraft computers: Oxymoron or future trend?

    Science.gov (United States)

    Manning, Robert M.

    1993-01-01

    Over the last few decades, application of current terrestrial computer technology in embedded spacecraft control systems has been expensive and wrought with many technical challenges. These challenges have centered on overcoming the extreme environmental constraints (protons, neutrons, gamma radiation, cosmic rays, temperature, vibration, etc.) that often preclude direct use of commercial off-the-shelf computer technology. Reliability, fault tolerance and power have also greatly constrained the selection of spacecraft control system computers. More recently, new constraints are being felt, cost and mass in particular, that have again narrowed the degrees of freedom spacecraft designers once enjoyed. This paper discusses these challenges, how they were previously overcome, how future trends in commercial computer technology will simplify (or hinder) selection of computer technology for spacecraft control applications, and what spacecraft electronic system designers can do now to circumvent them.

  18. Historical Mass, Power, Schedule, and Cost Growth for NASA Spacecraft

    Science.gov (United States)

    Hayhurst, Marc R.; Bitten, Robert E.; Shinn, Stephen A.; Judnick, Daniel C.; Hallgrimson, Ingrid E.; Youngs, Megan A.

    2016-01-01

    Although spacecraft developers have been moving towards standardized product lines as the aerospace industry has matured, NASA's continual need to push the cutting edge of science to accomplish unique, challenging missions can still lead to spacecraft resource growth over time. This paper assesses historical mass, power, cost, and schedule growth for multiple NASA spacecraft from the last twenty years and compares to industry reserve guidelines to understand where the guidelines may fall short. Growth is assessed from project start to launch, from the time of the preliminary design review (PDR) to launch and from the time of the critical design review (CDR) to launch. Data is also assessed not just at the spacecraft bus level, but also at the subsystem level wherever possible, to help obtain further insight into possible drivers of growth. Potential recommendations to minimize spacecraft mass, power, cost, and schedule growth for future missions are also discussed.

  19. Addressing EO-1 Spacecraft Pulsed Plasma Thruster EMI Concerns

    Science.gov (United States)

    Zakrzwski, C. M.; Davis, Mitch; Sarmiento, Charles; Bauer, Frank H. (Technical Monitor)

    2001-01-01

    The Pulsed Plasma Thruster (PPT) Experiment on the Earth Observing One (EO-1) spacecraft has been designed to demonstrate the capability of a new generation PPT to perform spacecraft attitude control. Results from PPT unit level radiated electromagnetic interference (EMI) tests led to concerns about potential interference problems with other spacecraft subsystems. Initial plans to address these concerns included firing the PPT at the spacecraft level both in atmosphere, with special ground support equipment. and in vacuum. During the spacecraft level tests, additional concerns where raised about potential harm to the Advanced Land Imager (ALI). The inadequacy of standard radiated emission test protocol to address pulsed electromagnetic discharges and the lack of resources required to perform compatibility tests between the PPT and an ALI test unit led to changes in the spacecraft level validation plan. An EMI shield box for the PPT was constructed and validated for spacecraft level ambient testing. Spacecraft level vacuum tests of the PPT were deleted. Implementation of the shield box allowed for successful spacecraft level testing of the PPT while eliminating any risk to the ALI. The ALI demonstration will precede the PPT demonstration to eliminate any possible risk of damage of ALI from PPT operation.

  20. Forming a method mindset : The role of knowledge and preference in facilitating heuristic method usage in design

    NARCIS (Netherlands)

    Daalhuizen, J.J.; Person, F.E.O.K.; Gattol, V.

    2013-01-01

    Both systematic and heuristic methods are common practice when designing. Yet, in teaching students how to design, heuristic methods are typically only granted a secondary role. So, how do designers and students develop a mindset for using heuristic methods? In this paper, we study how prior

  1. A shuttle and space station manipulator system for assembly, docking, maintenance, cargo handling and spacecraft retrieval (preliminary design). Volume 2: Concept development and selection

    Science.gov (United States)

    1972-01-01

    The overall program background, the various system concepts considered, and the rationale for the selected design are described. The concepts for each subsystem are also described and compared. Details are given for the requirements, boom configuration and dynamics, actuators, man/machine interface and control, visual system, control system, environmental control and life support, data processing, and materials.

  2. Passive Devices for Advanced Fluid Management aboard Spacecraft, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Acute challenges are faced by the designers of fluid systems for spacecraft because of the persistently unfamiliar and unforgiving low-g environment. For example,...

  3. The Physics and Technology of Solar Sail Spacecraft.

    Science.gov (United States)

    Dwivedi, B. N.; McInnes, C. R.

    1991-01-01

    Various aspects of the solar sail spacecraft such as solar sailing, solar sail design, navigation with solar sails, solar sail mission applications and future prospects for solar sailing are described. Several possible student projects are suggested. (KR)

  4. Distributed Control Architectures for Precision Spacecraft Formations, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — LaunchPoint Technologies, Inc. (LaunchPoint) proposes to develop synthesis methods and design architectures for distributed control systems in precision spacecraft...

  5. A shuttle and space station manipulator system for assembly, docking, maintenance, cargo handling and spacecraft retrieval (preliminary design). Volume 3: Concept analysis. Part 1: Technical

    Science.gov (United States)

    1972-01-01

    Information backing up the key features of the manipulator system concept and detailed technical information on the subsystems are presented. Space station assembly and shuttle cargo handling tasks are emphasized in the concept analysis because they involve shuttle berthing, transferring the manipulator boom between shuttle and station, station assembly, and cargo handling. Emphasis is also placed on maximizing commonality in the system areas of manipulator booms, general purpose end effectors, control and display, data processing, telemetry, dedicated computers, and control station design.

  6. How Spacecraft Fly Spaceflight Without Formulae

    CERN Document Server

    Swinerd, Graham

    2009-01-01

    About half a century ago a small satellite, Sputnik 1, was launched. The satellite did very little other than to transmit a radio signal to announce its presence in orbit. However, this humble beginning heralded the dawn of the Space Age. Today literally thousands of robotic spacecraft have been launched, many of which have flown to far-flung regions of the Solar System carrying with them the human spirit of scientific discovery and exploration. Numerous other satellites have been launched in orbit around the Earth providing services that support our technological society on the ground. How Spacecraft Fly: Spaceflight Without Formulae by Graham Swinerd focuses on how these spacecraft work. The book opens with a historical perspective of how we have come to understand our Solar System and the Universe. It then progresses through orbital flight, rocket science, the hostile environment within which spacecraft operate, and how they are designed. The concluding chapters give a glimpse of what the 21st century may ...

  7. Parameter Estimation of Spacecraft Fuel Slosh Model

    Science.gov (United States)

    Gangadharan, Sathya; Sudermann, James; Marlowe, Andrea; Njengam Charles

    2004-01-01

    Fuel slosh in the upper stages of a spinning spacecraft during launch has been a long standing concern for the success of a space mission. Energy loss through the movement of the liquid fuel in the fuel tank affects the gyroscopic stability of the spacecraft and leads to nutation (wobble) which can cause devastating control issues. The rate at which nutation develops (defined by Nutation Time Constant (NTC can be tedious to calculate and largely inaccurate if done during the early stages of spacecraft design. Pure analytical means of predicting the influence of onboard liquids have generally failed. A strong need exists to identify and model the conditions of resonance between nutation motion and liquid modes and to understand the general characteristics of the liquid motion that causes the problem in spinning spacecraft. A 3-D computerized model of the fuel slosh that accounts for any resonant modes found in the experimental testing will allow for increased accuracy in the overall modeling process. Development of a more accurate model of the fuel slosh currently lies in a more generalized 3-D computerized model incorporating masses, springs and dampers. Parameters describing the model include the inertia tensor of the fuel, spring constants, and damper coefficients. Refinement and understanding the effects of these parameters allow for a more accurate simulation of fuel slosh. The current research will focus on developing models of different complexity and estimating the model parameters that will ultimately provide a more realistic prediction of Nutation Time Constant obtained through simulation.

  8. Small Spacecraft for Planetary Science

    Science.gov (United States)

    Baker, John; Castillo-Rogez, Julie; Bousquet, Pierre-W.; Vane, Gregg; Komarek, Tomas; Klesh, Andrew

    2016-07-01

    As planetary science continues to explore new and remote regions of the Solar system with comprehensive and more sophisticated payloads, small spacecraft offer the possibility for focused and more affordable science investigations. These small spacecraft or micro spacecraft (attitude control and determination, capable computer and data handling, and navigation are being met by technologies currently under development to be flown on CubeSats within the next five years. This paper will discuss how micro spacecraft offer an attractive alternative to accomplish specific science and technology goals and what relevant technologies are needed for these these types of spacecraft. Acknowledgements: Part of this work is being carried out at the Jet Propulsion Laboratory, California Institute of Technology under contract to NASA. Government sponsorship acknowledged.

  9. MIDN: A spacecraft Micro-dosimeter mission

    International Nuclear Information System (INIS)

    Pisacane, V. L.; Ziegler, J. F.; Nelson, M. E.; Caylor, M.; Flake, D.; Heyen, L.; Youngborg, E.; Rosenfeld, A. B.; Cucinotta, F.; Zaider, M.; Dicello, J. F.

    2006-01-01

    MIDN (Micro-dosimetry instrument) is a payload on the MidSTAR-I spacecraft (Midshipman Space Technology Applications Research) under development at the United States Naval Academy. MIDN is a solid-state system being designed and constructed to measure Micro-dosimetric spectra to determine radiation quality factors for space environments. Radiation is a critical threat to the health of astronauts and to the success of missions in low-Earth orbit and space exploration. The system will consist of three separate sensors, one external to the spacecraft, one internal and one embedded in polyethylene. Design goals are mass <3 kg and power <2 W. The MidSTAR-I mission in 2006 will provide an opportunity to evaluate a preliminary version of this system. Its low power and mass makes it useful for the International Space Station and manned and unmanned interplanetary missions as a real-time system to assess and alert astronauts to enhanced radiation environments. (authors)

  10. Spectra and spacecraft

    Science.gov (United States)

    Moroz, V. I.

    2001-02-01

    In June 1999, Dr. Regis Courtin, Associate Editor of PSS, suggested that I write an article for the new section of this journal: "Planetary Pioneers". I hesitated , but decided to try. One of the reasons for my doubts was my primitive English, so I owe the reader an apology for this in advance. Writing took me much more time than I supposed initially, I have stopped and again returned to manuscript many times. My professional life may be divided into three main phases: pioneering work in ground-based IR astronomy with an emphasis on planetary spectroscopy (1955-1970), studies of the planets with spacecraft (1970-1989), and attempts to proceed with this work in difficult times. I moved ahead using the known method of trials and errors as most of us do. In fact, only a small percentage of efforts led to some important results, a sort of dry residue. I will try to describe below how has it been in my case: what may be estimated as the most important, how I came to this, what was around, etc.

  11. Trajectory Control of Rendezvous with Maneuver Target Spacecraft

    Science.gov (United States)

    Zhou, Zhinqiang

    2012-01-01

    In this paper, a nonlinear trajectory control algorithm of rendezvous with maneuvering target spacecraft is presented. The disturbance forces on the chaser and target spacecraft and the thrust forces on the chaser spacecraft are considered in the analysis. The control algorithm developed in this paper uses the relative distance and relative velocity between the target and chaser spacecraft as the inputs. A general formula of reference relative trajectory of the chaser spacecraft to the target spacecraft is developed and applied to four different proximity maneuvers, which are in-track circling, cross-track circling, in-track spiral rendezvous and cross-track spiral rendezvous. The closed-loop differential equations of the proximity relative motion with the control algorithm are derived. It is proven in the paper that the tracking errors between the commanded relative trajectory and the actual relative trajectory are bounded within a constant region determined by the control gains. The prediction of the tracking errors is obtained. Design examples are provided to show the implementation of the control algorithm. The simulation results show that the actual relative trajectory tracks the commanded relative trajectory tightly. The predicted tracking errors match those calculated in the simulation results. The control algorithm developed in this paper can also be applied to interception of maneuver target spacecraft and relative trajectory control of spacecraft formation flying.

  12. Research on spacecraft electrical power conversion

    Science.gov (United States)

    Wilson, T. G.

    1983-01-01

    The history of spacecraft electrical power conversion in literature, research and practice is reviewed. It is noted that the design techniques, analyses and understanding which were developed make today's contribution to power computers and communication installations. New applications which require more power, improved dynamic response, greater reliability, and lower cost are outlined. The switching mode approach in electronic power conditioning is discussed. Technical aspects of the research are summarized.

  13. A shuttle and space station manipulator system for assembly, docking, maintenance cargo handling and spacecraft retrieval (preliminary design). Volume 1: Management summary

    Science.gov (United States)

    1972-01-01

    A preliminary design is established for a general purpose manipulator system which can be used interchangeably on the shuttle and station and can be transferred back and forth between them. Control of the manipulator is accomplished by hard wiring from internal control stations in the shuttle or station. A variety of shuttle and station manipulator operations are considered including servicing the Large Space Telescope; however, emphasis is placed on unloading modules from the shuttle and assembling the space station. Simulation studies on foveal stereoscopic viewing and manipulator supervisory computer control have been accomplished to investigate the feasibility of their use in the manipulator system. The basic manipulator system consists of a single 18.3 m long, 7 degree of freedom (DOF), electrically acutated main boom with an auxiliary 3 DOF electrically actuated, extendible 18.3 m maximum length, lighting, and viewing boom. A 3 DOF orientor assembly is located at the tip of the viewing boom to provide camera pan, tilt, and roll.

  14. TTEthernet for Integrated Spacecraft Networks

    Science.gov (United States)

    Loveless, Andrew

    2015-01-01

    Aerospace projects have traditionally employed federated avionics architectures, in which each computer system is designed to perform one specific function (e.g. navigation). There are obvious downsides to this approach, including excessive weight (from so much computing hardware), and inefficient processor utilization (since modern processors are capable of performing multiple tasks). There has therefore been a push for integrated modular avionics (IMA), in which common computing platforms can be leveraged for different purposes. This consolidation of multiple vehicle functions to shared computing platforms can significantly reduce spacecraft cost, weight, and design complexity. However, the application of IMA principles introduces significant challenges, as the data network must accommodate traffic of mixed criticality and performance levels - potentially all related to the same shared computer hardware. Because individual network technologies are rarely so competent, the development of truly integrated network architectures often proves unreasonable. Several different types of networks are utilized - each suited to support a specific vehicle function. Critical functions are typically driven by precise timing loops, requiring networks with strict guarantees regarding message latency (i.e. determinism) and fault-tolerance. Alternatively, non-critical systems generally employ data networks prioritizing flexibility and high performance over reliable operation. Switched Ethernet has seen widespread success filling this role in terrestrial applications. Its high speed, flexibility, and the availability of inexpensive commercial off-the-shelf (COTS) components make it desirable for inclusion in spacecraft platforms. Basic Ethernet configurations have been incorporated into several preexisting aerospace projects, including both the Space Shuttle and International Space Station (ISS). However, classical switched Ethernet cannot provide the high level of network

  15. Streamlined Modeling for Characterizing Spacecraft Anomalous Behavior

    Science.gov (United States)

    Klem, B.; Swann, D.

    2011-09-01

    Anomalous behavior of on-orbit spacecraft can often be detected using passive, remote sensors which measure electro-optical signatures that vary in time and spectral content. Analysts responsible for assessing spacecraft operational status and detecting detrimental anomalies using non-resolved imaging sensors are often presented with various sensing and identification issues. Modeling and measuring spacecraft self emission and reflected radiant intensity when the radiation patterns exhibit a time varying reflective glint superimposed on an underlying diffuse signal contribute to assessment of spacecraft behavior in two ways: (1) providing information on body component orientation and attitude; and, (2) detecting changes in surface material properties due to the space environment. Simple convex and cube-shaped spacecraft, designed to operate without protruding solar panel appendages, may require an enhanced level of preflight characterization to support interpretation of the various physical effects observed during on-orbit monitoring. This paper describes selected portions of the signature database generated using streamlined signature modeling and simulations of basic geometry shapes apparent to non-imaging sensors. With this database, summarization of key observable features for such shapes as spheres, cylinders, flat plates, cones, and cubes in specific spectral bands that include the visible, mid wave, and long wave infrared provide the analyst with input to the decision process algorithms contained in the overall sensing and identification architectures. The models typically utilize baseline materials such as Kapton, paints, aluminum surface end plates, and radiators, along with solar cell representations covering the cylindrical and side portions of the spacecraft. Multiple space and ground-based sensors are assumed to be located at key locations to describe the comprehensive multi-viewing aspect scenarios that can result in significant specular reflection

  16. Conceptual design of a crewed reusable space transportation system aimed at parabolic flights: stakeholder analysis, mission concept selection, and spacecraft architecture definition

    Science.gov (United States)

    Fusaro, Roberta; Viola, Nicole; Fenoglio, Franco; Santoro, Francesco

    2017-03-01

    This paper proposes a methodology to derive architectures and operational concepts for future earth-to-orbit and sub-orbital transportation systems. In particular, at first, it describes the activity flow, methods, and tools leading to the generation of a wide range of alternative solutions to meet the established goal. Subsequently, the methodology allows selecting a small number of feasible options among which the optimal solution can be found. For the sake of clarity, the first part of the paper describes the methodology from a theoretical point of view, while the second part proposes the selection of mission concepts and of a proper transportation system aimed at sub-orbital parabolic flights. Starting from a detailed analysis of the stakeholders and their needs, the major objectives of the mission have been derived. Then, following a system engineering approach, functional analysis tools as well as concept of operations techniques allowed generating a very high number of possible ways to accomplish the envisaged goals. After a preliminary pruning activity, aimed at defining the feasibility of these concepts, more detailed analyses have been carried out. Going on through the procedure, the designer should move from qualitative to quantitative evaluations, and for this reason, to support the trade-off analysis, an ad-hoc built-in mission simulation software has been exploited. This support tool aims at estimating major mission drivers (mass, heat loads, manoeuverability, earth visibility, and volumetric efficiency) as well as proving the feasibility of the concepts. Other crucial and multi-domain mission drivers, such as complexity, innovation level, and safety have been evaluated through the other appropriate analyses. Eventually, one single mission concept has been selected and detailed in terms of layout, systems, and sub-systems, highlighting also logistic, safety, and maintainability aspects.

  17. Advanced Solar-propelled Cargo Spacecraft for Mars Missions

    Science.gov (United States)

    Auziasdeturenne, Jacqueline; Beall, Mark; Burianek, Joseph; Cinniger, Anna; Dunmire, Barbrina; Haberman, Eric; Iwamoto, James; Johnson, Stephen; Mccracken, Shawn; Miller, Melanie

    1989-01-01

    Three concepts for an unmanned, solar powered, cargo spacecraft for Mars support missions were investigated. These spacecraft are designed to carry a 50,000 kg payload from a low Earth orbit to a low Mars orbit. Each design uses a distinctly different propulsion system: A Solar Radiation Absorption (SRA) system, a Solar-Pumped Laser (SPL) system and a solar powered magnetoplasmadynamic (MPD) arc system. The SRA directly converts solar energy to thermal energy in the propellant through a novel process. In the SPL system, a pair of solar-pumped, multi-megawatt, CO2 lasers in sunsynchronous Earth orbit converts solar energy to laser energy. The MPD system used indium phosphide solar cells to convert sunlight to electricity, which powers the propulsion system. Various orbital transfer options are examined for these concepts. In the SRA system, the mother ship transfers the payload into a very high Earth orbit and a small auxiliary propulsion system boosts the payload into a Hohmann transfer to Mars. The SPL spacecraft and the SPL powered spacecraft return to Earth for subsequent missions. The MPD propelled spacecraft, however, remains at Mars as an orbiting space station. A patched conic approximation was used to determine a heliocentric interplanetary transfer orbit for the MPD propelled spacecraft. All three solar-powered spacecraft use an aerobrake procedure to place the payload into a low Mars parking orbit. The payload delivery times range from 160 days to 873 days (2.39 years).

  18. Time Frequency Analysis of Spacecraft Propellant Tank Spinning Slosh

    Science.gov (United States)

    Green, Steven T.; Burkey, Russell C.; Sudermann, James

    2010-01-01

    Many spacecraft are designed to spin about an axis along the flight path as a means of stabilizing the attitude of the spacecraft via gyroscopic stiffness. Because of the assembly requirements of the spacecraft and the launch vehicle, these spacecraft often spin about an axis corresponding to a minor moment of inertia. In such a case, any perturbation of the spin axis will cause sloshing motions in the liquid propellant tanks that will eventually dissipate enough kinetic energy to cause the spin axis nutation (wobble) to grow further. This spinning slosh and resultant nutation growth is a primary design problem of spinning spacecraft and one that is not easily solved by analysis or simulation only. Testing remains the surest way to address spacecraft nutation growth. This paper describes a test method and data analysis technique that reveal the resonant frequency and damping behavior of liquid motions in a spinning tank. Slosh resonant frequency and damping characteristics are necessary inputs to any accurate numerical dynamic simulation of the spacecraft.

  19. Spacecraft computer technology at Southwest Research Institute

    Science.gov (United States)

    Shirley, D. J.

    1993-01-01

    Southwest Research Institute (SwRI) has developed and delivered spacecraft computers for a number of different near-Earth-orbit spacecraft including shuttle experiments and SDIO free-flyer experiments. We describe the evolution of the basic SwRI spacecraft computer design from those weighing in at 20 to 25 lb and using 20 to 30 W to newer models weighing less than 5 lb and using only about 5 W, yet delivering twice the processing throughput. Because of their reduced size, weight, and power, these newer designs are especially applicable to planetary instrument requirements. The basis of our design evolution has been the availability of more powerful processor chip sets and the development of higher density packaging technology, coupled with more aggressive design strategies in incorporating high-density FPGA technology and use of high-density memory chips. In addition to reductions in size, weight, and power, the newer designs also address the necessity of survival in the harsh radiation environment of space. Spurred by participation in such programs as MSTI, LACE, RME, Delta 181, Delta Star, and RADARSAT, our designs have evolved in response to program demands to be small, low-powered units, radiation tolerant enough to be suitable for both Earth-orbit microsats and for planetary instruments. Present designs already include MIL-STD-1750 and Multi-Chip Module (MCM) technology with near-term plans to include RISC processors and higher-density MCM's. Long term plans include development of whole-core processors on one or two MCM's.

  20. Spacecraft Charging and the Microwave Anisotropy Probe Spacecraft

    Science.gov (United States)

    Timothy, VanSant J.; Neergaard, Linda F.

    1998-01-01

    The Microwave Anisotropy Probe (MAP), a MIDEX mission built in partnership between Princeton University and the NASA Goddard Space Flight Center (GSFC), will study the cosmic microwave background. It will be inserted into a highly elliptical earth orbit for several weeks and then use a lunar gravity assist to orbit around the second Lagrangian point (L2), 1.5 million kilometers, anti-sunward from the earth. The charging environment for the phasing loops and at L2 was evaluated. There is a limited set of data for L2; the GEOTAIL spacecraft measured relatively low spacecraft potentials (approx. 50 V maximum) near L2. The main area of concern for charging on the MAP spacecraft is the well-established threat posed by the "geosynchronous region" between 6-10 Re. The launch in the autumn of 2000 will coincide with the falling of the solar maximum, a period when the likelihood of a substorm is higher than usual. The likelihood of a substorm at that time has been roughly estimated to be on the order of 20% for a typical MAP mission profile. Because of the possibility of spacecraft charging, a requirement for conductive spacecraft surfaces was established early in the program. Subsequent NASCAP/GEO analyses for the MAP spacecraft demonstrated that a significant portion of the sunlit surface (solar cell cover glass and sunshade) could have nonconductive surfaces without significantly raising differential charging. The need for conductive materials on surfaces continually in eclipse has also been reinforced by NASCAP analyses.

  1. Research on intelligent power distribution system for spacecraft

    Science.gov (United States)

    Xia, Xiaodong; Wu, Jianju

    2017-10-01

    The power distribution system (PDS) mainly realizes the power distribution and management of the electrical load of the whole spacecraft, which is directly related to the success or failure of the mission, and hence is an important part of the spacecraft. In order to improve the reliability and intelligent degree of the PDS, and considering the function and composition of spacecraft power distribution system, this paper systematically expounds the design principle and method of the intelligent power distribution system based on SSPC, and provides the analysis and verification of the test data additionally.

  2. Stakeholder Engagement in Trial Design: Survey of Visitors to Critically Ill Patients Regarding Preferences for Outcomes and Treatment Options during Weaning from Mechanical Ventilation.

    Science.gov (United States)

    Burns, Karen E A; Jacob, Sonu Karottaiyamvelil; Aguirre, Valeria; Gomes, Janice; Mehta, Sangeeta; Rizvi, Leena

    2016-11-01

    Stakeholder engagement in research is expected to provide unique insights, make research investments more accountable and transparent, and ensure that future research is applicable to patients and family members. To inform the design of a trial of strategies for weaning from mechanical ventilation, we sought to identify preferences of patient visitors regarding outcome and treatment measures. We conducted an interviewer-administered questionnaire of visitors of critically ill patients in two family waiting rooms serving three intensive care units (ICUs) in Toronto, Canada. Respondents rated the importance of general and ventilation-related outcomes in two hypothetical scenarios (before a first spontaneous breathing trial, and after a failed spontaneous breathing trial) and selected a preferred technique for the breathing trials. With regard to the patient they were visiting, respondents identified the most important outcome to them at ICU admission, during the ICU stay, and at ICU discharge. We analyzed 322 questionnaires (95.5% response rate). All outcomes were highly rated (average range: 7.82-9.74). Across scenarios, outcomes rated as most important were ICU and hospital survival (9.72, 9.70), avoiding complications (9.45), quality of life (9.394), patient comfort (9.393), and returning to previous living arrangements (9.31). Overall, the most important ventilation-related outcomes were being ventilator-free (8.95), avoiding reintubation (8.905), and passing a spontaneous breathing trial (8.903). Passing a spontaneous breathing trial assumed greater importance after an initial failed attempt. "Time to event" outcomes were less important to visitors. We did not identify a preferred spontaneous breathing trial technique. Although ICU survival was the most important outcome at ICU admission and during the ICU stay, visitors rated quality of life higher than hospital survival at ICU discharge. Visitors to critically ill patients prioritized two general outcomes (ICU

  3. A small spacecraft for multipoint measurement of ionospheric plasma

    Science.gov (United States)

    Roberts, T. M.; Lynch, K. A.; Clayton, R. E.; Weiss, J.; Hampton, D. L.

    2017-07-01

    Measurement of ionospheric plasma is often performed by a single in situ device or remotely using cameras and radar. This article describes a small, low-resource, deployed spacecraft used as part of a local, multipoint measurement network. A B-field aligned sounding rocket ejects four of these spin-stabilized spacecraft in a cross pattern. In this application, each spacecraft carries two retarding potential analyzers which are used to determine plasma density, flow, and ion temperature. An inertial measurement unit and a light-emitting diode array are used to determine the position and orientation of the devices after deployment. The design of this spacecraft is first described, and then results from a recent test flight are discussed. This flight demonstrated the successful operation of the deployment mechanism and telemetry systems, provided some preliminary plasma measurements in a simple mid-latitude environment, and revealed several design issues.

  4. Spacecraft Environmental Interactions Technology, 1983

    Science.gov (United States)

    1985-01-01

    State of the art of environment interactions dealing with low-Earth-orbit plasmas; high-voltage systems; spacecraft charging; materials effects; and direction of future programs are contained in over 50 papers.

  5. Galileo spacecraft power management and distribution system

    International Nuclear Information System (INIS)

    Detwiler, R.C.; Smith, R.L.

    1990-01-01

    It has been twelve years since two Voyager spacecraft began the direct route to the outer planets. In October 1989 a single Galileo spacecraft started the return to Jupiter. Conceived as a simple Voyager look-alike, the Galileo power management and distribution (PMAD) system has undergone many iterations in configuration. Major changes to the PMAD resulted from dual spun slip ring limitations, variations in launch vehicle thrust capabilities, and launch delays. Lack of an adequate launch vehicle for an interplanetary mission of Galileo's size has resulted in an extremely long flight duration. A Venus-Earth-Earth Gravity Assist (VEEGA) tour, vital to attain the required energy, results in a 6 year trip to Jupiter and its moons. This paper provides a description of the Galileo PMAD and documents the design drivers that established the final as-built hardware

  6. Software for Automated Generation of Reduced Thermal Models for Spacecraft Thermal Control, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Thermal analysis is increasingly used in thermal engineering of spacecrafts in every stage, including design, test, and ground-operation simulation. Current...

  7. Space Environments and Spacecraft Effects Organization Concept

    Science.gov (United States)

    Edwards, David L.; Burns, Howard D.; Miller, Sharon K.; Porter, Ron; Schneider, Todd A.; Spann, James F.; Xapsos, Michael

    2012-01-01

    The National Aeronautics and Space Administration (NASA) is embarking on a course to expand human presence beyond Low Earth Orbit (LEO) while also expanding its mission to explore the solar system. Destinations such as Near Earth Asteroids (NEA), Mars and its moons, and the outer planets are but a few of the mission targets. Each new destination presents an opportunity to increase our knowledge of the solar system and the unique environments for each mission target. NASA has multiple technical and science discipline areas specializing in specific space environments disciplines that will help serve to enable these missions. To complement these existing discipline areas, a concept is presented focusing on the development of a space environments and spacecraft effects (SENSE) organization. This SENSE organization includes disciplines such as space climate, space weather, natural and induced space environments, effects on spacecraft materials and systems and the transition of research information into application. This space environment and spacecraft effects organization will be composed of Technical Working Groups (TWG). These technical working groups will survey customers and users, generate products, and provide knowledge supporting four functional areas: design environments, engineering effects, operational support, and programmatic support. The four functional areas align with phases in the program mission lifecycle and are briefly described below. Design environments are used primarily in the mission concept and design phases of a program. Engineering effects focuses on the material, component, sub-system and system-level selection and the testing to verify design and operational performance. Operational support provides products based on real time or near real time space weather to mission operators to aid in real time and near-term decision-making. The programmatic support function maintains an interface with the numerous programs within NASA, other federal

  8. Dynamics and control of Lorentz-augmented spacecraft relative motion

    CERN Document Server

    Yan, Ye; Yang, Yueneng

    2017-01-01

    This book develops a dynamical model of the orbital motion of Lorentz spacecraft in both unperturbed and J2-perturbed environments. It explicitly discusses three kinds of typical space missions involving relative orbital control: spacecraft hovering, rendezvous, and formation flying. Subsequently, it puts forward designs for both open-loop and closed-loop control schemes propelled or augmented by the geomagnetic Lorentz force. These control schemes are entirely novel and represent a significantly departure from previous approaches.

  9. Production objectives and trait preferences of village poultry producers of Ethiopia: implications for designing breeding schemes utilizing indigenous chicken genetic resources.

    Science.gov (United States)

    Dana, Nigussie; van der Waaij, Liesbeth H; Dessie, Tadelle; van Arendonk, Johan A M

    2010-10-01

    To generate information essential for the implementation of breeding schemes suitable for village poultry producers in Ethiopia, a survey was conducted aimed at defining the socioeconomic characteristics of the production environments in different geographic regions, understanding the important functions of chickens, identifying farmers' choice of chicken breeds and the underlying factors that determine the choice of genetic stock used. The survey included both questionnaire survey and a participatory group discussion. A total of 225 households (45 households from each of five Woredas) were interviewed. The questionnaire was designed to collect data covering general information on village poultry production such as socio-management characteristics, production objectives, population structure, breed choice and trait preferences, market preferences of specific traits, and farmers' selection practices. The participatory farmers' discussions were designed to involve stakeholders in defining the breeding objective "traits" and deriving their relative importance in the production environment based on the different functions of chickens and "traits" identified in the interviews. The results showed that production of eggs for consumption is the principal function of chickens in most regions followed by the use as source of income and meat for home consumption. The production system in all geographic regions studied revealed similar features generally characterized by extensive scavenging management, absence of immunization programs, increased risk of exposure of birds to disease and predators, and reproduction entirely based on uncontrolled natural mating and hatching of eggs using broody hens. Farmers' ratings of indigenous chickens with respect to modern breeds showed the highest significance of the adaptive traits in general, and the superior merits of indigenous chickens to high yielding exotic breeds in particular. Adaptation to the production environment was the most

  10. Housing Stakeholder Preferences for the “Soft” Features of Sustainable and Healthy Housing Design in the UK

    Science.gov (United States)

    Prochorskaite, Agne; Couch, Chris; Malys, Naglis; Maliene, Vida

    2016-01-01

    It is widely recognised that the quantity and sustainability of new homes in the UK need to increase. However, it is important that sustainable housing is regarded holistically, and not merely in environmental terms, and incorporates elements that enhance the quality of life, health and well-being of its users. This paper focuses on the “soft” features of sustainable housing, that is, the non-technological components of sustainable housing and neighbourhood design that can impact occupants’ health and well-being. Aims of the study are to ascertain the relative level of importance that key housing stakeholders attach to these features and to investigate whether the opinions of housing users and housing providers are aligned with regards to their importance. An online survey was carried out to gauge the level of importance that the key stakeholders, such as housing users, local authorities, housing associations, and developers (n = 235), attach to these features. Results revealed that while suitable indoor space was the feature regarded as most important by all stakeholders, there were also a number of disparities in opinion between housing users and housing providers (and among the different types of providers). This implies a scope for initiatives to achieve a better alignment between housing users and providers. PMID:26751465

  11. Definition of the topological structure of the automatic control system of spacecrafts

    International Nuclear Information System (INIS)

    KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" data-affiliation=" (Siberian State Aerospace University named after Academician M.F.Reshetnev 31 KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" >Zelenkov, P V; KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" data-affiliation=" (Siberian State Aerospace University named after Academician M.F.Reshetnev 31 KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" >Karaseva, M V; KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" data-affiliation=" (Siberian State Aerospace University named after Academician M.F.Reshetnev 31 KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" >Tsareva, E A; Tsarev, R Y

    2015-01-01

    The paper considers the problem of selection the topological structure of the automated control system of spacecrafts. The integer linear model of mathematical programming designed to define the optimal topological structure for spacecraft control is proposed. To solve the determination problem of topological structure of the control system of spacecrafts developed the procedure of the directed search of some structure variants according to the scheme 'Branch and bound'. The example of the automated control system of spacecraft development included the combination of ground control stations, managing the spacecraft of three classes with a geosynchronous orbit with constant orbital periods is presented

  12. Using stated preference methods to design cost-effective subsidy programs to induce technology adoption: an application to a stove program in southern Chile.

    Science.gov (United States)

    Gómez, Walter; Salgado, Hugo; Vásquez, Felipe; Chávez, Carlos

    2014-01-01

    We study the design of an economic incentive based program - a subsidy - to induce adoption of more efficient technology in a pollution reduction program in southern Chile. Stated preferences methods, contingent valuation (CV), and choice experiment (CE) are used to estimate the probability of adoption and the willingness to share the cost of a new technology by a household. The cost-effectiveness property of different subsidy schemes is explored numerically for different regulatory objectives. Our results suggest that households are willing to participate in voluntary programs and to contribute by paying a share of the cost of adopting more efficient technologies. We find that attributes of the existing and the new technology, beyond the price, are relevant determinant factors of the participation decision and payment. Limited access to credit markets for low income families can be a major barrier for an effective implementation of these types of programs. Variations in the design of the subsidy and on the regulator's objective and constraints can have significant impact on the level and the cost of reduction of aggregate emissions achieved. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Optimal platform design using non-dominated sorting genetic algorithm II and technique for order of preference by similarity to ideal solution; application to automotive suspension system

    Science.gov (United States)

    Shojaeefard, Mohammad Hassan; Khalkhali, Abolfazl; Faghihian, Hamed; Dahmardeh, Masoud

    2018-03-01

    Unlike conventional approaches where optimization is performed on a unique component of a specific product, optimum design of a set of components for employing in a product family can cause significant reduction in costs. Increasing commonality and performance of the product platform simultaneously is a multi-objective optimization problem (MOP). Several optimization methods are reported to solve these MOPs. However, what is less discussed is how to find the trade-off points among the obtained non-dominated optimum points. This article investigates the optimal design of a product family using non-dominated sorting genetic algorithm II (NSGA-II) and proposes the employment of technique for order of preference by similarity to ideal solution (TOPSIS) method to find the trade-off points among the obtained non-dominated results while compromising all objective functions together. A case study for a family of suspension systems is presented, considering performance and commonality. The results indicate the effectiveness of the proposed method to obtain the trade-off points with the best possible performance while maximizing the common parts.

  14. Artist concept of Galileo spacecraft

    Science.gov (United States)

    1988-01-01

    Galileo spacecraft is illustrated in artist concept. Gallileo, named for the Italian astronomer, physicist and mathematician who is credited with construction of the first complete, practical telescope in 1620, will make detailed studies of Jupiter. A cooperative program with the Federal Republic of Germany the Galileo mission will amplify information acquired by two Voyager spacecraft in their brief flybys. Galileo is a two-element system that includes a Jupiter-orbiting observatory and an entry probe. Jet Propulsion Laboratory (JPL) is Galileo project manager and builder of the main spacecraft. Ames Research Center (ARC) has responsibility for the entry probe, which was built by Hughes Aircraft Company and General Electric. Galileo will be deployed from the payload bay (PLB) of Atlantis, Orbiter Vehicle (OV) 104, during mission STS-34.

  15. Constructive Preference Elicitation

    Directory of Open Access Journals (Sweden)

    Paolo Dragone

    2018-01-01

    Full Text Available When faced with large or complex decision problems, human decision makers (DM can make costly mistakes, due to inherent limitations of their memory, attention, and knowledge. Preference elicitation tools assist the decision maker in overcoming these limitations. They do so by interactively learning the DM’s preferences through appropriately chosen queries and suggesting high-quality outcomes based on the preference estimates. Most state-of-the-art techniques, however, fail in constructive settings, where the goal is to synthesize a custom or entirely novel configuration rather than choosing the best option among a given set of candidates. Many wide-spread problems are constructive in nature: customizing composite goods such as cars and computers, bundling products, recommending touristic travel plans, designing apartments, buildings, or urban layouts, etc. In these settings, the full set of outcomes is humongous and can not be explicitly enumerated, and the solution must be synthesized via constrained optimization. In this article, we describe recent approaches especially designed for constructive problems, outlining the underlying ideas and their differences as well as their limitations. In presenting them, we especially focus on novel issues that the constructive setting brings forth, such as how to deal with sparsity of the DM’s preferences, how to properly frame the interaction, and how to achieve efficient synthesis of custom instances.

  16. Standardization and Economics of Nuclear Spacecraft, Final Report, Phase I, Sense Study

    Energy Technology Data Exchange (ETDEWEB)

    1973-03-01

    Feasibility and cost benefits of nuclear-powered standardized spacecraft are investigated. The study indicates that two shuttle-launched nuclear-powered spacecraft should be able to serve the majority of unmanned NASA missions anticipated for the 1980's. The standard spacecraft include structure, thermal control, power, attitude control, some propulsion capability and tracking, telemetry, and command subsystems. One spacecraft design, powered by the radioisotope thermoelectric generator, can serve missions requiring up to 450 watts. The other spacecraft design, powered by similar nuclear heat sources in a Brayton-cycle generator, can serve missions requiring up to 21000 watts. Design concepts and trade-offs are discussed. The conceptual designs selected are presented and successfully tested against a variety of missions. The thermal design is such that both spacecraft are capable of operating in any earth orbit and any orientation without modification. Three-axis stabilization is included. Several spacecraft can be stacked in the shuttle payload compartment for multi-mission launches. A reactor-powered thermoelectric generator system, operating at an electric power level of 5000 watts, is briefly studied for applicability to two test missions of divers requirements. A cost analysis indicates that use of the two standardized spacecraft offers sizable savings in comparison with specially designed solar-powered spacecraft. There is a duplicate copy.

  17. Aircraft, ships, spacecraft, nuclear plants and quality

    International Nuclear Information System (INIS)

    Patrick, M.G.

    1984-05-01

    A few quality assurance programs outside the purview of the Nuclear Regulatory Commission were studied to identify features or practices which the NRC could use to enhance its program for assuring quality in the design and construction of nuclear power plants. The programs selected were: the manufacture of large commercial transport aircraft, regulated by the Federal Aviation Administration; US Navy shipbuilding; commercial shipbuilding regulated by the Maritime Administration and the US Coast Guard; Government-owned nuclear plants under the Department of Energy; spacecraft under the National Aeronautics and Space Administration; and the construction of nuclear power plants in Canada, West Germany, France, Japan, Sweden, and the United Kingdom

  18. Results from active spacecraft potential control on the Geotail spacecraft

    International Nuclear Information System (INIS)

    Schmidt, R.; Arends, H.; Pedersen, A.

    1995-01-01

    A low and actively controlled electrostatic potential on the outer surfaces of a scientific spacecraft is very important for accurate measurements of cold plasma electrons and ions and the DC to low-frequency electric field. The Japanese/NASA Geotail spacecraft carriers as part of its scientific payload a novel ion emitter for active control of the electrostatic potential on the surface of the spacecraft. The aim of the ion emitter is to reduce the positive surface potential which is normally encountered in the outer magnetosphere when the spacecraft is sunlit. Ion emission clamps the surface potential to near the ambient plasma potential. Without emission control, Geotail has encountered plasma conditions in the lobes of the magnetotail which resulted in surface potentials of up to about +70 V. The ion emitter proves to be able to discharge the outer surfaces of the spacecraft and is capable of keeping the surface potential stable at about +2 V. This potential is measured with respect to one of the electric field probes which are current biased and thus kept at a potential slightly above the ambient plasma potential. The instrument uses the liquid metal field ion emission principle to emit indium ions. The ion beam energy is about 6 keV and the typical total emission current amounts to about 15 μA. Neither variations in the ambient plasma conditions nor operation of two electron emitters on Geotail produce significant variations of the controlled surface potential as long as the resulting electron emission currents remain much smaller than the ion emission current. Typical results of the active potential control are shown, demonstrating the surface potential reduction and its stability over time. 25 refs., 5 figs

  19. Preferences for behavioural, analytic and gestalt psychotherapy.

    Science.gov (United States)

    Sobel, H J

    1979-09-01

    This study investigated preferences for behavioural, analytic and gestalt psychotherapy among a sample of 40 SES class III and IV adult females and 67 college freshmen who had never been actual therapy patients. A scaled survey assessed general preference, preference given an imagined long-standing depressive disorder, preference given an imagined specific phobia, and preference for the therapist-patient relationship. Three audio tapes were designed, each describing one of the modalities. High inter-rater reliability and agreement were determined by three independent judges. Results showed that young females had a general preference for gestalt therapy. Young and old females, but not young males, significantly preferred behavioural therapy for a specific phobia. Under forced-choice conditions the group as a whole significantly preferred gestalt therapy. No differences were found for the relationship or preference given a depressive disorder. Preference was hypothesized as a cognitive structure with potential use in therapist-client matching.

  20. Charging in the environment of large spacecraft

    International Nuclear Information System (INIS)

    Lai, S.T.

    1993-01-01

    This paper discusses some potential problems of spacecraft charging as a result of interactions between a large spacecraft, such as the Space Station, and its environment. Induced electric field, due to VXB effect, may be important for large spacecraft at low earth orbits. Differential charging, due to different properties of surface materials, may be significant when the spacecraft is partly in sunshine and partly in shadow. Triple-root potential jump condition may occur because of differential charging. Sudden onset of severe differential charging may occur when an electron or ion beam is emitted from the spacecraft. The beam may partially return to the ''hot spots'' on the spacecraft. Wake effects, due to blocking of ambient ion trajectories, may result in an undesirable negative potential region in the vicinity of a large spacecraft. Outgassing and exhaust may form a significant spacecraft induced environment; ionization may occur. Spacecraft charging and discharging may affect the electronic components on board

  1. Mesh Network Architecture for Enabling Inter-Spacecraft Communication

    Science.gov (United States)

    Becker, Christopher; Merrill, Garrick

    2017-01-01

    To enable communication between spacecraft operating in a formation or small constellation, a mesh network architecture was developed and tested using a time division multiple access (TDMA) communication scheme. The network is designed to allow for the exchange of telemetry and other data between spacecraft to enable collaboration between small spacecraft. The system uses a peer-to-peer topology with no central router, so that it does not have a single point of failure. The mesh network is dynamically configurable to allow for addition and subtraction of new spacecraft into the communication network. Flight testing was performed using an unmanned aerial system (UAS) formation acting as a spacecraft analogue and providing a stressing environment to prove mesh network performance. The mesh network was primarily devised to provide low latency, high frequency communication but is flexible and can also be configured to provide higher bandwidth for applications desiring high data throughput. The network includes a relay functionality that extends the maximum range between spacecraft in the network by relaying data from node to node. The mesh network control is implemented completely in software making it hardware agnostic, thereby allowing it to function with a wide variety of existing radios and computing platforms..

  2. Time maintenance system for the BMDO MSX spacecraft

    Science.gov (United States)

    Hermes, Martin J.

    1994-01-01

    The Johns Hopkins University Applied Physics Laboratory (APL) is responsible for designing and implementing a clock maintenance system for the Ballistic Missile Defense Organizations (BMDO) Midcourse Space Experiment (MSX) spacecraft. The MSX spacecraft has an on-board clock that will be used to control execution of time-dependent commands and to time tag all science and housekeeping data received from the spacecraft. MSX mission objectives have dictated that this spacecraft time, UTC(MSX), maintain a required accuracy with respect to UTC(USNO) of +/- 10 ms with a +/- 1 ms desired accuracy. APL's atomic time standards and the downlinked spacecraft time were used to develop a time maintenance system that will estimate the current MSX clock time offset during an APL pass and make estimates of the clock's drift and aging using the offset estimates from many passes. Using this information, the clock's accuracy will be maintained by uplinking periodic clock correction commands. The resulting time maintenance system is a combination of offset measurement, command/telemetry, and mission planning hardware and computing assets. All assets provide necessary inputs for deciding when corrections to the MSX spacecraft clock must be made to maintain its required accuracy without inhibiting other mission objectives. The MSX time maintenance system is described as a whole and the clock offset measurement subsystem, a unique combination of precision time maintenance and measurement hardware controlled by a Macintosh computer, is detailed. Simulations show that the system estimates the MSX clock offset to less than+/- 33 microseconds.

  3. An Orbit Propagation Software for Mars Orbiting Spacecraft

    Directory of Open Access Journals (Sweden)

    Young-Joo Song

    2004-12-01

    Full Text Available An orbit propagation software for the Mars orbiting spacecraft has been developed and verified in preparations for the future Korean Mars missions. Dynamic model for Mars orbiting spacecraft has been studied, and Mars centered coordinate systems are utilized to express spacecraft state vectors. Coordinate corrections to the Mars centered coordinate system have been made to adjust the effects caused by Mars precession and nutation. After spacecraft enters Sphere of Influence (SOI of the Mars, the spacecraft experiences various perturbation effects as it approaches to Mars. Every possible perturbation effect is considered during integrations of spacecraft state vectors. The Mars50c gravity field model and the Mars-GRAM 2001 model are used to compute perturbation effects due to Mars gravity field and Mars atmospheric drag, respectively. To compute exact locations of other planets, JPL's DE405 ephemerides are used. Phobos and Deimos's ephemeris are computed using analytical method because their informations are not released with DE405. Mars Global Surveyor's mapping orbital data are used to verify the developed propagator performances. After one Martian day propagation (12 orbital periods, the results show about maximum ±5 meter errors, in every position state components(radial, cross-track and along-track, when compared to these from the Astrogator propagation in the Satellite Tool Kit. This result shows high reliability of the developed software which can be used to design near Mars missions for Korea, in future.

  4. Planning Inmarsat's second generation of spacecraft

    Science.gov (United States)

    Williams, W. P.

    1982-09-01

    The next generation of studies of the Inmarsat service are outlined, such as traffic forecasting studies, communications capacity estimates, space segment design, cost estimates, and financial analysis. Traffic forecasting will require future demand estimates, and a computer model has been developed which estimates demand over the Atlantic, Pacific, and Indian ocean regions. Communications estimates are based on traffic estimates, as a model converts traffic demand into a required capacity figure for a given area. The Erlang formula is used, requiring additional data such as peak hour ratios and distribution estimates. Basic space segment technical requirements are outlined (communications payload, transponder arrangements, etc), and further design studies involve such areas as space segment configuration, launcher and spacecraft studies, transmission planning, and earth segment configurations. Cost estimates of proposed design parameters will be performed, but options must be reduced to make construction feasible. Finally, a financial analysis will be carried out in order to calculate financial returns.

  5. LDEF materials results for spacecraft applications: Executive summary

    Science.gov (United States)

    Whitaker, A. F.; Dooling, D.

    1995-03-01

    To address the challenges of space environmental effects, NASA designed the Long Duration Exposure Facility (LDEF) for an 18-month mission to expose thousands of samples of candidate materials that might be used on a space station or other orbital spacecraft. LDEF was launched in April 1984 and was to have been returned to Earth in 1985. Changes in mission schedules postponed retrieval until January 1990, after 69 months in orbit. Analyses of the samples recovered from LDEF have provided spacecraft designers and managers with the most extensive data base on space materials phenomena. Many LDEF samples were greatly changed by extended space exposure. Among even the most radially altered samples, NASA and its science teams are finding a wealth of surprising conclusions and tantalizing clues about the effects of space on materials. Many were discussed at the first two LDEF results conferences and subsequent professional papers. The LDEF Materials Results for Spacecraft Applications Conference was convened in Huntsville to discuss implications for spacecraft design. Already, paint and thermal blanket selections for space station and other spacecraft have been affected by LDEF data. This volume synopsizes those results.

  6. Interactive genetic algorithm for user-centered design of distributed conservation practices in a watershed: An examination of user preferences in objective space and user behavior

    Science.gov (United States)

    Piemonti, Adriana Debora; Babbar-Sebens, Meghna; Mukhopadhyay, Snehasis; Kleinberg, Austin

    2017-05-01

    Interactive Genetic Algorithms (IGA) are advanced human-in-the-loop optimization methods that enable humans to give feedback, based on their subjective and unquantified preferences and knowledge, during the algorithm's search process. While these methods are gaining popularity in multiple fields, there is a critical lack of data and analyses on (a) the nature of interactions of different humans with interfaces of decision support systems (DSS) that employ IGA in water resources planning problems and on (b) the effect of human feedback on the algorithm's ability to search for design alternatives desirable to end-users. In this paper, we present results and analyses of observational experiments in which different human participants (surrogates and stakeholders) interacted with an IGA-based, watershed DSS called WRESTORE to identify plans of conservation practices in a watershed. The main goal of this paper is to evaluate how the IGA adapts its search process in the objective space to a user's feedback, and identify whether any similarities exist in the objective space of plans found by different participants. Some participants focused on the entire watershed, while others focused only on specific local subbasins. Additionally, two different hydrology models were used to identify any potential differences in interactive search outcomes that could arise from differences in the numerical values of benefits displayed to participants. Results indicate that stakeholders, in comparison to their surrogates, were more likely to use multiple features of the DSS interface to collect information before giving feedback, and dissimilarities existed among participants in the objective space of design alternatives.

  7. Heat pipe applications for future Air Force spacecraft

    International Nuclear Information System (INIS)

    Mahefkey, T.; Barthelemy, R.R.

    1980-01-01

    This paper summarizes the envisioned, future usage of high and low temperature heat pipes in advanced Air Force spacecraft. Thermal control requirements for a variety of communications, surveillance, and space defense missions are forecast. Thermal design constraints implied by survivability to potential weapons effects are outlined. Applications of heat pipes to meet potential low and high power spacecraft mission requirements and envisioned design constraints are suggested. A brief summary of past Air Force sponsored heat pipe development efforts is presented and directions for future development outlined, including those applicable to advanced photovoltaic and nuclear power subsystem applications of heat pipes

  8. Small Rocket/Spacecraft Technology (SMART) Platform

    Science.gov (United States)

    Esper, Jaime; Flatley, Thomas P.; Bull, James B.; Buckley, Steven J.

    2011-01-01

    The NASA Goddard Space Flight Center (GSFC) and the Department of Defense Operationally Responsive Space (ORS) Office are exercising a multi-year collaborative agreement focused on a redefinition of the way space missions are designed and implemented. A much faster, leaner and effective approach to space flight requires the concerted effort of a multi-agency team tasked with developing the building blocks, both programmatically and technologically, to ultimately achieve flights within 7-days from mission call-up. For NASA, rapid mission implementations represent an opportunity to find creative ways for reducing mission life-cycle times with the resulting savings in cost. This in tum enables a class of missions catering to a broader audience of science participants, from universities to private and national laboratory researchers. To that end, the SMART (Small Rocket/Spacecraft Technology) micro-spacecraft prototype demonstrates an advanced avionics system with integrated GPS capability, high-speed plug-and-playable interfaces, legacy interfaces, inertial navigation, a modular reconfigurable structure, tunable thermal technology, and a number of instruments for environmental and optical sensing. Although SMART was first launched inside a sounding rocket, it is designed as a free-flyer.

  9. Characterization of dust aggregates in the vicinity of the Rosetta spacecraft

    Science.gov (United States)

    Güttler, C.; Hasselmann, P. H.; Li, Y.; Fulle, M.; Tubiana, C.; Kovacs, G.; Agarwal, J.; Sierks, H.; Fornasier, S.; Hofmann, M.; Gutiérrez Marqués, P.; Ott, T.; Drolshagen, E.; Bertini, I.; Osiris Team

    2017-09-01

    In a Rosetta/OSIRIS imaging activity in June 2015, we have observed the dynamic motion of particles close to the spacecraft. Due to the focal setting of the OSIRIS Wide Angle Camera (WAC), these particles were blurred, which can be used to measure their distances to the spacecraft. We detected 108 dust aggregates over a 130 minutes long sequence, and find that their sizes are around a millimetre and their distances cluster between 2 m and 40 m from the spacecraft. Their number densities are about a factor 10 higher than expected for the overall coma and highly fluctuating. Their velocities are small compared to the spacecraft orbital motion and directed away from the spacecraft, towards the comet. From this we conclude that they have interacted with the spacecraft and assess three possible scenarios. We prefer a scenario where centimeter-sized aggregates collide with the spacecraft and we would observe the fragments. Ablation of a dust layer on the spacecraft's z panel when rotated towards the sun is a reasonable alternative. We could also measure an acceleration for a subset of 18 aggregates, which is directed away from the sun and can be explain by a rocket effect, which requires a minimum ice fraction in the order of 0.1%

  10. Standardized spacecraft: a methodology for decision making. AMS report No. 1199

    International Nuclear Information System (INIS)

    Greenberg, J.S.; Nichols, R.A.

    1974-01-01

    As the space program matures, more and more attention is being focused on ways to reduce the costs of performing space missions. Standardization has been suggested as a way of providing cost reductions. The question of standardization at the system level, in particular, the question of the desirability of spacecraft standardization for geocentric space missions is addressed. The spacecraft is considered to be a bus upon which mission oriented equipment, the payload, is mounted. Three basic questions are considered: (1) is spacecraft standardization economically desirable; (2) if spacecraft standardization is economically desirable, what standardized spacecraft configuration or mix of configurations and technologies should be developed; and (3) if standardized spacecraft are to be developed, what power levels should they be designed for. A methodology which has been developed and which is necessary to follow if the above questions are to be answered and informed decisions made relative to spacecraft standardization is described. To illustrate the decision making problems and the need for the developed methodology and the data requirements, typical standardized spacecraft have been considered. Both standardized solar and nuclear-powered spacecraft and mission specialized spacecraft have been conceptualized and performance and cost estimates have been made. These estimates are not considered to be of sufficient accuracy to allow decisions regarding spacecraft mix and power levels to be made at this time. The estimates are deemed of sufficient accuracy so as to demonstrate the desirability of spacecraft standardization and the methodology (as well as the need for the methodology) which is necessary to decide upon the best mix of standardized spacecraft and their design power levels. (U.S.)

  11. Multiple spacecraft Michelson stellar interferometer

    Science.gov (United States)

    Stachnik, R. V.; Arnold, D.; Melroy, P.; Mccormack, E. F.; Gezari, D. Y.

    1984-01-01

    Results of an orbital analysis and performance assessment of SAMSI (Spacecraft Array for Michelson Spatial Interferometry) are presented. The device considered includes two one-meter telescopes in orbits which are identical except for slightly different inclinations; the telescopes achieve separations as large as 10 km and relay starlight to a central station which has a one-meter optical delay line in one interferometer arm. It is shown that a 1000-km altitude, zero mean inclination orbit affords natural scanning of the 10-km baseline with departures from optical pathlength equality which are well within the corrective capacity of the optical delay line. Electric propulsion is completely adequate to provide the required spacecraft motions, principally those needed for repointing. Resolution of 0.00001 arcsec and magnitude limits of 15 to 20 are achievable.

  12. Spacecraft Tests of General Relativity

    Science.gov (United States)

    Anderson, John D.

    1997-01-01

    Current spacecraft tests of general relativity depend on coherent radio tracking referred to atomic frequency standards at the ground stations. This paper addresses the possibility of improved tests using essentially the current system, but with the added possibility of a space-borne atomic clock. Outside of the obvious measurement of the gravitational frequency shift of the spacecraft clock, a successor to the suborbital flight of a Scout D rocket in 1976 (GP-A Project), other metric tests would benefit most directly by a possible improved sensitivity for the reduced coherent data. For purposes of illustration, two possible missions are discussed. The first is a highly eccentric Earth orbiter, and the second a solar-conjunction experiment to measure the Shapiro time delay using coherent Doppler data instead of the conventional ranging modulation.

  13. Attitude Fusion Techniques for Spacecraft

    DEFF Research Database (Denmark)

    Bjarnø, Jonas Bækby

    Spacecraft platform instability constitutes one of the most significant limiting factors in hyperacuity pointing and tracking applications, yet the demand for accurate, timely and reliable attitude information is ever increasing. The PhD research project described within this dissertation has...... served to investigate the solution space for augmenting the DTU μASC stellar reference sensor with a miniature Inertial Reference Unit (IRU), thereby obtaining improved bandwidth, accuracy and overall operational robustness of the fused instrument. Present day attitude determination requirements are met...... of the instrument, and affecting operations during agile and complex spacecraft attitude maneuvers. As such, there exists a theoretical foundation for augmenting the high frequency performance of the μASC instrument, by harnessing the complementary nature of optical stellar reference and inertial sensor technology...

  14. Nonlinearity-induced spacecraft tumbling

    International Nuclear Information System (INIS)

    Amos, A.K.

    1994-01-01

    An existing tumbling criterion for the dumbbell satellite in planar librations is reexamined and modified to reflect a recently identified tumbling mode associated with the horizontal attitude orientation. It is shown that for any initial attitude there exists a critical angular rate below which the motion is oscillatory and harmonic and beyond which a continuous tumbling will ensue. If the angular rate is at the critical value the spacecraft drifts towards the horizontal attitude from which a spontaneous periodic tumbling occurs

  15. COMPARATION STUDY OF INSTANT NOODLE NONG SHIM KOREA AND INDOMIE INDONESIA AS THE FEFFECT OF PACKAGING DESIGN POINT OF INTEREST TO THE CONSUMER BRAND PREFERENCE

    Directory of Open Access Journals (Sweden)

    Listia Natadjaja

    2003-01-01

    Full Text Available Sudah sejak lama%2C masyarakat mengkonsumsi mie instant. Di Korea mi instan yang disebut Ramyon%2C adalah salah satu makanan yang popular dan banyak dijual di toko-toko kecil%2C supermarket%2C restoran dan kantin. Mi instan yang terkenal di Korea diproduksi oleh Nong Shim Co.%2C Ltd. Di Indonesia%2C kebanyakan orang mengkonsumsi mi instan dengan alasan praktis%2C cepat saji dan lain sebagainya. Indomie%2C yang diproduksi oleh PT. Indofood adalah merk nomor satu dan menjadi pemimpin pasar pada pasar mi instan. Dalam studi komparasi antara dua merk terkenal ini%2C perlu diketahui seberapa jauh peran desain kemasan dalam menarik minat konsumen terhadap pilihan merk. Abstract in Bahasa Indonesia : For a long time%2C people have consumed the instant noodle. In Korea%2C instant noodle%2C which is called Ramyon%2C is one of popular food and it is often seen in the retail shop%2C supermarket%2C restaurant and cafeteria. Instant noodle that has a famous brand in Korea is produce by Nong Shim Co.%2C Ltd. In Indonesia%2C many people have consumed the instant noodle with practice reason%2C fast serving%2C and etc. Indomie%2C produced by PT. Indofood%2C is the number one brand and become the market leader of instant noodle. Comparing at two famous brand of instant noodle%2C it is needed to be known how far the effect of packaging design can attract the consumer brand preference. desain kemasan%2C pilihan merk%2C mi instan.

  16. Using a partially randomized patient preference study design to evaluate the therapeutic effect of acupuncture and cupping therapy for fibromyalgia: study protocol for a partially randomized controlled trial.

    Science.gov (United States)

    Cao, Hui-Juan; Liu, Jian-Ping; Hu, Hui; Wang, Nissi S

    2014-07-10

    Conducting randomized controlled trials on traditional Chinese non-drug therapies has been limited by factors such as patient preference to specific treatment modality. The aim of this study is to investigate the feasibility of applying a partially randomized patient preference (PRPP) trial model in evaluating the efficacy of two types of traditional Chinese medicine therapies, acupuncture and cupping, for fibromyalgia while accounting for patients' preference of either therapeutic modality. This protocol was approved by the Institutional Ethics Committee of affiliated Dongfang Hospital, Beijing University of Chinese Medicine (approval number: 2013052104-2). One hundred participants with fibromyalgia will be included in this study. Diagnosis of fibromyalgia will be based on the American College of Rheumatology criteria. Before treatment, participants will be interviewed for their preference toward acupuncture or cupping therapy. Fifty participants with no preference will be randomly assigned to one of the two groups and another 50 participants with strong preference to either acupuncture or cupping will receive what they choose. For acupuncture and cupping therapy, the main acupoints used will be tender points (Ashi). Treatment will be three times a week for 5 consecutive weeks with a follow-up period of 12 weeks. Outcome measures will be qualitative (patient expectation and satisfaction) and quantitative (pain intensity, quality of life, depression assessment). NCT01869712 (in clinicaltrials.gov, on 22nd May 2013).

  17. A spacecraft computer repairable via command.

    Science.gov (United States)

    Fimmel, R. O.; Baker, T. E.

    1971-01-01

    The MULTIPAC is a central data system developed for deep-space probes with the distinctive feature that it may be repaired during flight via command and telemetry links by reprogramming around the failed unit. The computer organization uses pools of identical modules which the program organizes into one or more computers called processors. The interaction of these modules is dynamically controlled by the program rather than hardware. In the event of a failure, new programs are entered which reorganize the central data system with a somewhat reduced total processing capability aboard the spacecraft. Emphasis is placed on the evolution of the system architecture and the final overall system design rather than the specific logic design.

  18. Integrating standard operating procedures with spacecraft automation, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Spacecraft automation has the potential to assist crew members and spacecraft operators in managing spacecraft systems during extended space missions. Automation can...

  19. Spacecraft Fire Safety Research at NASA Glenn Research Center

    Science.gov (United States)

    Meyer, Marit

    2016-01-01

    Appropriate design of fire detection systems requires knowledge of both the expected fire signature and the background aerosol levels. Terrestrial fire detection systems have been developed based on extensive study of terrestrial fires. Unfortunately there is no corresponding data set for spacecraft fires and consequently the fire detectors in current spacecraft were developed based upon terrestrial designs. In low gravity, buoyant flow is negligible which causes particles to concentrate at the smoke source, increasing their residence time, and increasing the transport time to smoke detectors. Microgravity fires have significantly different structure than those in 1-g which can change the formation history of the smoke particles. Finally the materials used in spacecraft are different from typical terrestrial environments where smoke properties have been evaluated. It is critically important to detect a fire in its early phase before a flame is established, given the fixed volume of air on any spacecraft. Consequently, the primary target for spacecraft fire detection is pyrolysis products rather than soot. Experimental investigations have been performed at three different NASA facilities which characterize smoke aerosols from overheating common spacecraft materials. The earliest effort consists of aerosol measurements in low gravity, called the Smoke Aerosol Measurement Experiment (SAME), and subsequent ground-based testing of SAME smoke in 55-gallon drums with an aerosol reference instrument. Another set of experiments were performed at NASAs Johnson Space Center White Sands Test Facility (WSTF), with additional fuels and an alternate smoke production method. Measurements of these smoke products include mass and number concentration, and a thermal precipitator was designed for this investigation to capture particles for microscopic analysis. The final experiments presented are from NASAs Gases and Aerosols from Smoldering Polymers (GASP) Laboratory, with selected

  20. Temperature control of the Mariner class spacecraft - A seven mission summary.

    Science.gov (United States)

    Dumas, L. N.

    1973-01-01

    Mariner spacecraft have completed five missions of scientific investigation of the planets. Two additional missions are planned. A description of the thermal design of these seven spacecraft is given herein. The factors which have influenced the thermal design include the mission requirements and constraints, the flight environment, certain programmatic considerations and the experience gained as each mission is completed. These factors are reviewed and the impact of each on thermal design and developmental techniques is assessed. It is concluded that the flight success of these spacecraft indicates that adequate temperature control has been obtained, but that improvements in design data, hardware performance and analytical techniques are needed.

  1. Spacecraft Jitter Attenuation Using Embedded Piezoelectric Actuators

    Science.gov (United States)

    Belvin, W. Keith

    1995-01-01

    Remote sensing from spacecraft requires precise pointing of measurement devices in order to achieve adequate spatial resolution. Unfortunately, various spacecraft disturbances induce vibrational jitter in the remote sensing instruments. The NASA Langley Research Center has performed analysis, simulations, and ground tests to identify the more promising technologies for minimizing spacecraft pointing jitter. These studies have shown that the use of smart materials to reduce spacecraft jitter is an excellent match between a maturing technology and an operational need. This paper describes the use of embedding piezoelectric actuators for vibration control and payload isolation. In addition, recent advances in modeling, simulation, and testing of spacecraft pointing jitter are discussed.

  2. VIERS- User Preference Service

    Data.gov (United States)

    Department of Veterans Affairs — The Preferences service provides a means to store, retrieve, and manage user preferences. The service supports definition of enterprise wide preferences, as well as...

  3. Relativity time-delay experiments utilizing 'Mariner' spacecraft

    Science.gov (United States)

    Esposito, P. B.; Anderson, J. D.

    1974-01-01

    Relativity predicts that the transit time of a signal propagated from the earth to a spacecraft and retransmitted back to earth ought to exhibit an additional, variable time delay. The present work describes some of the analytical techniques employed in experiments using Mariner spacecraft designed to test the accuracy of this prediction. Two types of data are analyzed in these relativity experiments; these include phase-coherent, two-way Doppler shift and round-trip, transit-time measurements. Results of Mariner 6 and 7 relativistic time-delay experiments are in agreement with Einstein's theory of general relativity with an uncertainty of 3%.

  4. Multi-kilowatt modularized spacecraft power processing system development

    International Nuclear Information System (INIS)

    Andrews, R.E.; Hayden, J.H.; Hedges, R.T.; Rehmann, D.W.

    1975-07-01

    A review of existing information pertaining to spacecraft power processing systems and equipment was accomplished with a view towards applicability to the modularization of multi-kilowatt power processors. Power requirements for future spacecraft were determined from the NASA mission model-shuttle systems payload data study which provided the limits for modular power equipment capabilities. Three power processing systems were compared to evaluation criteria to select the system best suited for modularity. The shunt regulated direct energy transfer system was selected by this analysis for a conceptual design effort which produced equipment specifications, schematics, envelope drawings, and power module configurations

  5. Comprehension of Spacecraft Telemetry Using Hierarchical Specifications of Behavior

    Science.gov (United States)

    Havelund, Klaus; Joshi, Rajeev

    2014-01-01

    A key challenge in operating remote spacecraft is that ground operators must rely on the limited visibility available through spacecraft telemetry in order to assess spacecraft health and operational status. We describe a tool for processing spacecraft telemetry that allows ground operators to impose structure on received telemetry in order to achieve a better comprehension of system state. A key element of our approach is the design of a domain-specific language that allows operators to express models of expected system behavior using partial specifications. The language allows behavior specifications with data fields, similar to other recent runtime verification systems. What is notable about our approach is the ability to develop hierarchical specifications of behavior. The language is implemented as an internal DSL in the Scala programming language that synthesizes rules from patterns of specification behavior. The rules are automatically applied to received telemetry and the inferred behaviors are available to ground operators using a visualization interface that makes it easier to understand and track spacecraft state. We describe initial results from applying our tool to telemetry received from the Curiosity rover currently roving the surface of Mars, where the visualizations are being used to trend subsystem behaviors, in order to identify potential problems before they happen. However, the technology is completely general and can be applied to any system that generates telemetry such as event logs.

  6. Small Spacecraft Constellation Concept for Mars Atmospheric Radio Occultations

    Science.gov (United States)

    Asmar, S. W.; Mannucci, A. J.; Ao, C. O.; Kobayashi, M. M.; Lazio, J.; Marinan, A.; Massone, G.; McCandless, S. E.; Preston, R. A.; Seubert, J.; Williamson, W.

    2017-12-01

    First demonstrated in 1965 when Mariner IV flew by Mars and determined the salient features of its atmosphere, radio occultation experiments have been carried out on numerous planetary missions with great discoveries. These experiments utilize the now classic configuration of a signal from a single planetary spacecraft to Earth receiving stations, where the science data are acquired. The Earth science community advanced the technique to utilizing a constellation of spacecraft with the radio occultation links between the spacecraft, enabled by the infrastructure of the Global Positioning System. With the advent of small and less costly spacecraft, such as planetary CubeSats and other variations, such as the anticipated innovative Mars Cube One mission, crosslinks among small spacecraft can be used to study other planets in the near future. Advantages of this type of experiment include significantly greater geographical coverage, which could reach global coverage over a few weeks with a small number of spacecraft. Repeatability of the global coverage can lead to examining temperature-pressure profiles and ionospheric electron density profiles, on daily, seasonal, annual, or other time scales of interest. The higher signal-to-noise ratio for inter-satellite links, compared to a link to Earth, decreases the design demands on the instrumentation (smaller antennas and transmitters, etc.). After an actual Mars crosslink demonstration, this concept has been in development using Mars as a possible target. Scientific objectives, delivery methods, operational scenarios and end-to-end configuration have been documented. Science objectives include determining the state and variability of the lower Martian atmosphere, which has been an identified as a high priority objective by the Mars Exploration Program Analysis Group, particularly as it relates to entry, descent, and landing and ascent for future crewed and robotic missions. This paper will present the latest research on the

  7. Human factors issues for interstellar spacecraft

    Science.gov (United States)

    Cohen, Marc M.; Brody, Adam R.

    1991-01-01

    Developments in research on space human factors are reviewed in the context of a self-sustaining interstellar spacecraft based on the notion of traveling space settlements. Assumptions about interstellar travel are set forth addressing costs, mission durations, and the need for multigenerational space colonies. The model of human motivation by Maslow (1970) is examined and directly related to the design of space habitat architecture. Human-factors technology issues encompass the human-machine interface, crew selection and training, and the development of spaceship infrastructure during transtellar flight. A scenario for feasible instellar travel is based on a speed of 0.5c, a timeframe of about 100 yr, and an expandable multigenerational crew of about 100 members. Crew training is identified as a critical human-factors issue requiring the development of perceptual and cognitive aids such as expert systems and virtual reality.

  8. Nutation instability of spinning solid rocket motor spacecraft

    Directory of Open Access Journals (Sweden)

    Dan YANG

    2017-08-01

    Full Text Available The variation of mass, and moment of inertia of a spin-stabilized spacecraft leads to concern about the nutation instability. Here a careful analysis on the nutation instability is performed on a spacecraft propelled by solid rocket booster (SRB. The influences of specific solid propellant designs on transversal angular velocity are discussed. The results show that the typical SRB of End Burn suppresses the non-principal axial angular velocity. On the contrary, the frequently used SRB of Radial Burn could amplify the transversal angular velocity. The nutation instability caused by a design of Radial Burn could be remedied by the addition of End Burn at the same time based on the study of the combination design of both End Burn and Radial Burn. The analysis of the results proposes the design conception of how to control the nutation motion. The method is suitable to resolve the nutation instability of solid rocket motor with complex propellant patterns.

  9. Radiation shielding calculations for the vista spacecraft

    International Nuclear Information System (INIS)

    Sahin, Suemer; Sahin, Haci Mehmet; Acir, Adem

    2005-01-01

    The VISTA spacecraft design concept has been proposed for manned or heavy cargo deep space missions beyond earth orbit with inertial fusion energy propulsion. Rocket propulsion is provided by fusion power deposited in the inertial confined fuel pellet debris and with the help of a magnetic nozzle. The calculations for the radiation shielding have been revised under the fact that the highest jet efficiency of the vehicle could be attained only if the propelling plasma would have a narrow temperature distribution. The shield mass could be reduced from 600 tons in the original design to 62 tons. Natural and enriched lithium were the principle shielding materials. The allowable nuclear heating in the superconducting magnet coils (up to 5 mW/cm 3 ) is taken as the crucial criterion for dimensioning the radiation shielding structure of the spacecraft. The space craft mass is 6000 tons. Total peak nuclear power density in the coils is calculated as ∼5.0 mW/cm 3 for a fusion power output of 17 500 MW. The peak neutron heating density is ∼2.0 mW/cm 3 , and the peak γ-ray heating density is ∼3.0 mW/cm 3 (on different points) using natural lithium in the shielding. However, the volume averaged heat generation in the coils is much lower, namely 0.21, 0.71 and 0.92 mW/cm 3 for the neutron, γ-ray and total nuclear heating, respectively. The coil heating will be slightly lower if highly enriched 6 Li (90%) is used instead of natural lithium. Peak values are then calculated as 2.05, 2.15 and 4.2 mW/cm 3 for the neutron, γ-ray and total nuclear heating, respectively. The corresponding volume averaged heat generation in the coils became 0.19, 0.58 and 0.77 mW/cm 3

  10. Guidance, navigation, and control subsystem for the EOS-AM spacecraft

    Science.gov (United States)

    Linder, David M.; Tolek, Joseph T.; Lombardo, John

    1992-01-01

    This paper presents the preliminary design of the Guidance, Navigation, and Control (GN&C) subsystem for the EOS-AM spacecraft and specifically focuses on the GN&C Normal Mode design. First, a brief description of the EOS-AM science mission, instruments, and system-level spacecraft design is provided. Next, an overview of the GN&C subsystem functional and performance requirements, hardware, and operating modes is presented. Then, the GN&C Normal Mode attitude determination, attitude control, and navigation systems are detailed. Finally, descriptions of the spacecraft's overall jitter performance and Safe Mode are provided.

  11. Elicitation of ostomy pouch preferences

    DEFF Research Database (Denmark)

    Bonnichsen, Ole

    2011-01-01

    Background: Previous studies about patients who have undergone ostomy surgery commonly address the issues of the surgery, complications, preoperative counseling, quality of life, and psychosocial changes following surgery. Only a limited number of studies deal with how technical improvements...... in stoma care would affect patients and, to the author's knowledge, the present study is the first to elicit preferences for potential improvements in ostomy pouches in the form of monetary values. Objective: This article examines and measures Swedish patients' preferences for potential improvements...... in ostomy pouch attributes. The theory, study design, elicitation procedure, and resulting preference structure of the sample is described. Methods: A discrete-choice experiment (DCE) was used to elicit preferences. Respondents were asked to choose between alternatives in choice sets, in which each...

  12. Spacecraft Dynamic Characterization by Strain Energies Method

    Science.gov (United States)

    Bretagne, J.-M.; Fragnito, M.; Massier, S.

    2002-01-01

    In the last years the significant increase in satellite broadcasting demand, with the wide band communication dawn, has given a great impulse to the telecommunication satellite market. The big demand is translated from operators (such as SES/Astra, Eutelsat, Intelsat, Inmarsat, EuroSkyWay etc.) in an increase of orders of telecom satellite to the world industrials. The largest part of these telecom satellite orders consists of Geostationary platforms which grow more and more in mass (over 5 tons) due to an ever longer demanded lifetime (up to 20 years), and become more complex due to the need of implementing an ever larger number of repeaters, antenna reflectors and feeds, etc... In this frame, the mechanical design and verification of these large spacecraft become difficult and ambitious at the same time, driven by the dry mass limitation objective. By the Finite Element Method (FEM), and on the basis of the telecom satellite heritage of a world leader constructor such as Alcatel Space Industries it is nowadays possible to model these spacecraft in a realistic and confident way in order to identify the main global dynamic aspects such as mode shapes, mass participation and/or dynamic responses. But on the other hand, one of the main aims consists in identifying soon in a program the most critical aspects of the system behavior in the launch dynamic environment, such as possible dynamic coupling between the different subsystems and secondary structures of the spacecraft (large deployable reflectors, thrusters, etc.). To this aim a numerical method has been developed in the frame of the Alcatel SPACEBUS family program, using MSC/Nastran capabilities and it is presented in this paper. The method is based on Spacecraft sub-structuring and strain energy calculation. The method mainly consists of two steps : 1) subsystem modal strain energy ratio (with respect to the global strain energy); 2) subsystem strain energy calculation for each mode according to the base driven

  13. Preferences for distributional impacts of climate policy

    DEFF Research Database (Denmark)

    Svenningsen, Lea Skræp; Thorsen, Bo Jellesmark

    for such preferences is lacking. We design a discrete choice experiment that varies how climate policies affect the income of people living in the future in three geographical regions. The experiment is implemented on a representative sample of the Danish population and preferences are modelled in a latent class model...... expresses some form of distributional preferences, but shows positive preferences for costs, suggesting that responses could be influenced by strategic behaviour and over-signalling of commitment. Our results provide support for the inclusion of social preferences regarding distributional effects of climate...

  14. Transitivity of Preferences

    Science.gov (United States)

    Regenwetter, Michel; Dana, Jason; Davis-Stober, Clintin P.

    2011-01-01

    Transitivity of preferences is a fundamental principle shared by most major contemporary rational, prescriptive, and descriptive models of decision making. To have transitive preferences, a person, group, or society that prefers choice option "x" to "y" and "y" to "z" must prefer "x" to…

  15. Estimating Torque Imparted on Spacecraft Using Telemetry

    Science.gov (United States)

    Lee, Allan Y.; Wang, Eric K.; Macala, Glenn A.

    2013-01-01

    There have been a number of missions with spacecraft flying by planetary moons with atmospheres; there will be future missions with similar flybys. When a spacecraft such as Cassini flies by a moon with an atmosphere, the spacecraft will experience an atmospheric torque. This torque could be used to determine the density of the atmosphere. This is because the relation between the atmospheric torque vector and the atmosphere density could be established analytically using the mass properties of the spacecraft, known drag coefficient of objects in free-molecular flow, and the spacecraft velocity relative to the moon. The density estimated in this way could be used to check results measured by science instruments. Since the proposed methodology could estimate disturbance torque as small as 0.02 N-m, it could also be used to estimate disturbance torque imparted on the spacecraft during high-altitude flybys.

  16. Computer simulation of spacecraft/environment interaction

    International Nuclear Information System (INIS)

    Krupnikov, K.K.; Makletsov, A.A.; Mileev, V.N.; Novikov, L.S.; Sinolits, V.V.

    1999-01-01

    This report presents some examples of a computer simulation of spacecraft interaction with space environment. We analysed a set data on electron and ion fluxes measured in 1991-1994 on geostationary satellite GORIZONT-35. The influence of spacecraft eclipse and device eclipse by solar-cell panel on spacecraft charging was investigated. A simple method was developed for an estimation of spacecraft potentials in LEO. Effects of various particle flux impact and spacecraft orientation are discussed. A computer engineering model for a calculation of space radiation is presented. This model is used as a client/server model with WWW interface, including spacecraft model description and results representation based on the virtual reality markup language

  17. Computer simulation of spacecraft/environment interaction

    CERN Document Server

    Krupnikov, K K; Mileev, V N; Novikov, L S; Sinolits, V V

    1999-01-01

    This report presents some examples of a computer simulation of spacecraft interaction with space environment. We analysed a set data on electron and ion fluxes measured in 1991-1994 on geostationary satellite GORIZONT-35. The influence of spacecraft eclipse and device eclipse by solar-cell panel on spacecraft charging was investigated. A simple method was developed for an estimation of spacecraft potentials in LEO. Effects of various particle flux impact and spacecraft orientation are discussed. A computer engineering model for a calculation of space radiation is presented. This model is used as a client/server model with WWW interface, including spacecraft model description and results representation based on the virtual reality markup language.

  18. Attitude tracking control of flexible spacecraft with large amplitude slosh

    Science.gov (United States)

    Deng, Mingle; Yue, Baozeng

    2017-12-01

    This paper is focused on attitude tracking control of a spacecraft that is equipped with flexible appendage and partially filled liquid propellant tank. The large amplitude liquid slosh is included by using a moving pulsating ball model that is further improved to estimate the settling location of liquid in microgravity or a zero-g environment. The flexible appendage is modelled as a three-dimensional Bernoulli-Euler beam, and the assumed modal method is employed. A hybrid controller that combines sliding mode control with an adaptive algorithm is designed for spacecraft to perform attitude tracking. The proposed controller has proved to be asymptotically stable. A nonlinear model for the overall coupled system including spacecraft attitude dynamics, liquid slosh, structural vibration and control action is established. Numerical simulation results are presented to show the dynamic behaviors of the coupled system and to verify the effectiveness of the control approach when the spacecraft undergoes the disturbance produced by large amplitude slosh and appendage vibration. Lastly, the designed adaptive algorithm is found to be effective to improve the precision of attitude tracking.

  19. Optimal Autonomous Spacecraft Resiliency Maneuvers Using Metaheuristics

    Science.gov (United States)

    2014-09-15

    This work was accepted for published by the American Institute of Aeronautics and Astronautics (AIAA) Journal of Spacecraft and Rockets in July 2014...publication in the AIAA Journal of Spacecraft and Rockets . Chapter 5 introduces an impulsive maneuvering strategy to deliver a spacecraft to its final...upon arrival r2 and v2 , respectively. The variable T2 determines the time of flight needed to make the maneuver, and the variable θ2 determines the

  20. Optimal Electrical Energy Slewing for Reaction Wheel Spacecraft

    Science.gov (United States)

    Marsh, Harleigh Christian

    The results contained in this dissertation contribute to a deeper level of understanding to the energy required to slew a spacecraft using reaction wheels. This work addresses the fundamental manner in which spacecrafts are slewed (eigenaxis maneuvering), and demonstrates that this conventional maneuver can be dramatically improved upon in regards to reduction of energy, dissipative losses, as well as peak power. Energy is a fundamental resource that effects every asset, system, and subsystem upon a spacecraft, from the attitude control system which orients the spacecraft, to the communication subsystem to link with ground stations, to the payloads which collect scientific data. For a reaction wheel spacecraft, the attitude control system is a particularly heavy load on the power and energy resources on a spacecraft. The central focus of this dissertation is reducing the burden which the attitude control system places upon the spacecraft in regards to electrical energy, which is shown in this dissertation to be a challenging problem to computationally solve and analyze. Reducing power and energy demands can have a multitude of benefits, spanning from the initial design phase, to in-flight operations, to potentially extending the mission life of the spacecraft. This goal is approached from a practical standpoint apropos to an industry-flight setting. Metrics to measure electrical energy and power are developed which are in-line with the cost associated to operating reaction wheel based attitude control systems. These metrics are incorporated into multiple families of practical high-dimensional constrained nonlinear optimal control problems to reduce the electrical energy, as well as the instantaneous power burdens imposed by the attitude control system upon the spacecraft. Minimizing electrical energy is shown to be a problem in L1 optimal control which is nonsmooth in regards to state variables as well as the control. To overcome the challenge of nonsmoothness, a

  1. Ulysses spacecraft control and monitoring system

    Science.gov (United States)

    Hamer, P. A.; Snowden, P. J.

    1991-01-01

    The baseline Ulysses spacecraft control and monitoring system (SCMS) concepts and the converted SCMS, residing on a DEC/VAX 8350 hardware, are considered. The main functions of the system include monitoring and displaying spacecraft telemetry, preparing spacecraft commands, producing hard copies of experimental data, and archiving spacecraft telemetry. The SCMS system comprises over 20 subsystems ranging from low-level utility routines to the major monitoring and control software. These in total consist of approximately 55,000 lines of FORTRAN source code and 100 VMS command files. The SCMS major software facilities are described, including database files, telemetry processing, telecommanding, archiving of data, and display of telemetry.

  2. Operationally Responsive Spacecraft Subsystem, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Saber Astronautics proposes spacecraft subsystem control software which can autonomously reconfigure avionics for best performance during various mission conditions....

  3. The Earth Observing System AM Spacecraft - Thermal Control Subsystem

    Science.gov (United States)

    Chalmers, D.; Fredley, J.; Scott, C.

    1993-01-01

    Mission requirements for the EOS-AM Spacecraft intended to monitor global changes of the entire earth system are considered. The spacecraft is based on an instrument set containing the Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER), Clouds and Earth's Radiant Energy System (CERES), Multiangle Imaging Spectro-Radiometer (MISR), Moderate-Resolution Imaging Spectrometer (MODIS), and Measurements of Pollution in the Troposphere (MOPITT). Emphasis is placed on the design, analysis, development, and verification plans for the unique EOS-AM Thermal Control Subsystem (TCS) aimed at providing the required environments for all the onboard equipment in a densely packed layout. The TCS design maximizes the use of proven thermal design techniques and materials, in conjunction with a capillary pumped two-phase heat transport system for instrument thermal control.

  4. Guidance and Navigation for Rendezvous and Proximity Operations with a Non-Cooperative Spacecraft at Geosynchronous Orbit

    Science.gov (United States)

    Barbee, Brent William; Carpenter, J. Russell; Heatwole, Scott; Markley, F. Landis; Moreau, Michael; Naasz, Bo J.; VanEepoel, John

    2010-01-01

    The feasibility and benefits of various spacecraft servicing concepts are currently being assessed, and all require that the servicer spacecraft perform rendezvous, proximity, and capture operations with the target spacecraft to be serviced. Many high-value spacecraft, which would be logical targets for servicing from an economic point of view, are located in geosynchronous orbit, a regime in which autonomous rendezvous and capture operations are not commonplace. Furthermore, existing GEO spacecraft were not designed to be serviced. Most do not have cooperative relative navigation sensors or docking features, and some servicing applications, such as de-orbiting of a non-functional spacecraft, entail rendezvous and capture with a spacecraft that may be non-functional or un-controlled. Several of these challenges have been explored via the design of a notional mission in which a nonfunctional satellite in geosynchronous orbit is captured by a servicer spacecraft and boosted into super-synchronous orbit for safe disposal. A strategy for autonomous rendezvous, proximity operations, and capture is developed, and the Orbit Determination Toolbox (ODTBX) is used to perform a relative navigation simulation to assess the feasibility of performing the rendezvous using a combination of angles-only and range measurements. Additionally, a method for designing efficient orbital rendezvous sequences for multiple target spacecraft is utilized to examine the capabilities of a servicer spacecraft to service multiple targets during the course of a single mission.

  5. Touchless Despinning of Asteroids and Comets via Neutral Beam Emitting Spacecraft

    Data.gov (United States)

    National Aeronautics and Space Administration — This project seeks to design, build, and test a device that is capable of despinning an asteroid without the need for affixing the spacecraft to the surface. This...

  6. Aerogel Insulation for the Thermal Protection of Venus Spacecraft, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — One of NASA's primary goals for the next decade is the design, development and launch of a spacecraft aimed at the in-situ exploration of the deep atmosphere and...

  7. Integrated Spacecraft Navigation and Communication Using Radio, Optical, and X-rays, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This program proposes to design and evaluate novel technology of X-ray navigation for augmentation and increased capability of high data-rate spacecraft...

  8. Alcohol demand and risk preference.

    Science.gov (United States)

    Dave, Dhaval; Saffer, Henry

    2008-12-01

    Both economists and psychologists have studied the concept of risk preference. Economists categorize individuals as more or less risk-tolerant based on the marginal utility of income. Psychologists categorize individuals' propensity towards risk based on harm avoidance, novelty seeking and reward dependence traits. The two concepts of risk are related, although the instruments used for empirical measurement are quite different. Psychologists have found risk preference to be an important determinant of alcohol consumption; however economists have not included risk preference in studies of alcohol demand. This is the first study to examine the effect of risk preference on alcohol consumption in the context of a demand function. The specifications employ multiple waves from the Panel Study of Income Dynamics (PSID) and the Health and Retirement Study (HRS), which permit the estimation of age-specific models based on nationally representative samples. Both of these data sets include a unique and consistent survey instrument designed to directly measure risk preference in accordance with the economist's definition. This study estimates the direct impact of risk preference on alcohol demand and also explores how risk preference affects the price elasticity of demand. The empirical results indicate that risk preference has a significant negative effect on alcohol consumption, with the prevalence and consumption among risk-tolerant individuals being 6-8% higher. Furthermore, the tax elasticity is similar across both risk-averse and risk-tolerant individuals. This suggests that tax policies are as equally effective in deterring alcohol consumption among those who have a higher versus a lower propensity for alcohol use.

  9. Measuring higher order ambiguity preferences

    NARCIS (Netherlands)

    A. Baillon (Aurélien); Schlesinger, H. (Harris); G. van de Kuilen (Gijs)

    2017-01-01

    textabstractWe report the results from an experiment designed to measure attitudes towards ambiguity beyond ambiguity aversion. In particular, we implement recently-proposed model-free preference conditions of ambiguity prudence and ambiguity temperance. Ambiguity prudence has been shown to play an

  10. Performance Testing of a Photocatalytic Oxidation Module for Spacecraft Cabin Atmosphere Revitalization

    Science.gov (United States)

    Perry, Jay L.; Abney, Morgan B.; Frederick, Kenneth R.; Scott, Joseph P.; Kaiser, Mark; Seminara, Gary; Bershitsky, Alex

    2011-01-01

    Photocatalytic oxidation (PCO) is a candidate process technology for use in high volumetric flow rate trace contaminant control applications in sealed environments. The targeted application for PCO as applied to crewed spacecraft life support system architectures is summarized. Technical challenges characteristic of PCO are considered. Performance testing of a breadboard PCO reactor design for mineralizing polar organic compounds in a spacecraft cabin atmosphere is described. Test results are analyzed and compared to results reported in the literature for comparable PCO reactor designs.

  11. Investigation of tenuous plasma environment using Active Spacecraft Potential Control (ASPOC) on Magnetospheric Multiscale (MMS) Mission

    Science.gov (United States)

    Nakamura, Rumi; Jeszenszky, Harald; Torkar, Klaus; Andriopoulou, Maria; Fremuth, Gerhard; Taijmar, Martin; Scharlemann, Carsten; Svenes, Knut; Escoubet, Philippe; Prattes, Gustav; Laky, Gunter; Giner, Franz; Hoelzl, Bernhard

    2015-04-01

    The NASA's Magnetospheric Multiscale (MMS) Mission is planned to be launched on March 12, 2015. The scientific objectives of the MMS mission are to explore and understand the fundamental plasma physics processes of magnetic reconnection, particle acceleration and turbulence in the Earth's magnetosphere. The region of scientific interest of MMS is in a tenuous plasma environment where the positive spacecraft potential reaches an equilibrium at several tens of Volts. An Active Spacecraft Potential Control (ASPOC) instrument neutralizes the spacecraft potential by releasing positive charge produced by indium ion emitters. ASPOC thereby reduces the potential in order to improve the electric field and low-energy particle measurement. The method has been successfully applied on other spacecraft such as Cluster and Double Star. Two ASPOC units are present on each of the MMS spacecraft. Each unit contains four ion emitters, whereby one emitter per instrument is operated at a time. ASPOC for MMS includes new developments in the design of the emitters and the electronics enabling lower spacecraft potentials, higher reliability, and a more uniform potential structure in the spacecraft's sheath compared to previous missions. Model calculations confirm the findings from previous applications that the plasma measurements will not be affected by the beam's space charge. A perfectly stable spacecraft potential precludes the utilization of the spacecraft as a plasma probe, which is a conventional technique used to estimate ambient plasma density from the spacecraft potential. The small residual variations of the potential controlled by ASPOC, however, still allow to determine ambient plasma density by comparing two closely separated spacecraft and thereby reconstructing the uncontrolled potential variation from the controlled potential. Regular intercalibration of controlled and uncontrolled potentials is expected to increase the reliability of this new method.

  12. Proposed gravity-gradient dynamics experiments in lunar orbit using the RAE-B spacecraft

    Science.gov (United States)

    Blanchard, D. L.; Walden, H.

    1973-01-01

    A series of seven gravity-gradient dynamics experiments is proposed utilizing the Radio Astronomy Explorer (RAE-B) spacecraft in lunar orbit. It is believed that none of the experiments will impair the spacecraft structure or adversely affect the continuation of the scientific mission of the satellite. The first experiment is designed to investigate the spacecraft dynamical behavior in the absence of libration damper action and inertia. It requires stable gravity-gradient capture of the spacecraft in lunar orbit with small amplitude attitude librations as a prerequisite. Four subsequent experiments involve partial retraction, ultimately followed by full redeployment, of one or two of the 230-meter booms forming the lunar-directed Vee-antenna. These boom length change operations will induce moderate amplitude angular librations of the spacecraft.

  13. A preference for migration

    OpenAIRE

    Stark, Oded

    2007-01-01

    At least to some extent migration behavior is the outcome of a preference for migration. The pattern of migration as an outcome of a preference for migration depends on two key factors: imitation technology and migration feasibility. We show that these factors jointly determine the outcome of a preference for migration and we provide examples that illustrate how the prevalence and transmission of a migration-forming preference yield distinct migration patterns. In particular, the imitation of...

  14. Social Preferences and Strategic Uncertainty

    DEFF Research Database (Denmark)

    Cabrales, Antonio; Miniaci, Raffaele; Piovesan, Marco

    This paper reports experimental evidence on a stylized labor market. The experiment is designed as a sequence of three phases. In the first two phases, P1 and P2; agents face simple games, which we use to estimate subjects' social and reciprocity concerns, together with their beliefs. In the last......, for both principals and agents. Finally, we also see that social preferences explain, to a large extent, matching between principals and agents, since agents display a marked propensity to work for principals with similar social preferences...

  15. Ascent performance feasibility for next-generation spacecraft

    Science.gov (United States)

    Mancuso, Salvatore Massimo

    This thesis deals with the optimization of the ascent trajectories for single-stage suborbital (SSSO), single-stage-to-orbit (SSTO), and two-stage-to-orbit (TSTO) rocket-powered spacecraft. The maximum payload weight problem has been solved using the sequential gradient-restoration algorithm. For the TSTO case, some modifications to the original version of the algorithm have been necessary in order to deal with discontinuities due to staging and the fact that the functional being minimized depends on interface conditions. The optimization problem is studied for different values of the initial thrust-to-weight ratio in the range 1.3 to 1.6, engine specific impulse in the range 400 to 500 sec, and spacecraft structural factor in the range 0.08 to 0.12. For the TSTO configuration, two subproblems are studied: uniform structural factor between stages and nonuniform structural factor between stages. Due to the regular behavior of the results obtained, engineering approximations have been developed which connect the maximum payload weight to the engine specific impulse and spacecraft structural factor; in turn, this leads to useful design considerations. Also, performance sensitivity to the scale of the aerodynamic drag is studied, and it is shown that its effect on payload weight is relatively small, even for drag changes approaching ± 50%. The main conclusions are that: the design of a SSSO configuration appears to be feasible; the design of a SSTO configuration might be comfortably feasible, marginally feasible, or unfeasible, depending on the parameter values assumed; the design of a TSTO configuration is not only feasible, but its payload appears to be considerably larger than that of a SSTO configuration. Improvements in engine specific impulse and spacecraft structural factor are desirable and crucial for SSTO feasibility; indeed, it appears that aerodynamic improvements do not yield significant improvements in payload weight.

  16. Flight Plasma Diagnostics for High-Power, Solar-Electric Deep-Space Spacecraft

    Science.gov (United States)

    Johnson, Lee; De Soria-Santacruz Pich, Maria; Conroy, David; Lobbia, Robert; Huang, Wensheng; Choi, Maria; Sekerak, Michael J.

    2018-01-01

    NASA's Asteroid Redirect Robotic Mission (ARRM) project plans included a set of plasma and space environment instruments, the Plasma Diagnostic Package (PDP), to fulfill ARRM requirements for technology extensibility to future missions. The PDP objectives were divided into the classes of 1) Plasma thruster dynamics, 2) Solar array-specific environmental effects, 3) Plasma environmental spacecraft effects, and 4) Energetic particle spacecraft environment. A reference design approach and interface requirements for ARRM's PDP was generated by the PDP team at JPL and GRC. The reference design consisted of redundant single-string avionics located on the ARRM spacecraft bus as well as solar array, driving and processing signals from multiple copies of several types of plasma, effects, and environments sensors distributed over the spacecraft and array. The reference design sensor types were derived in part from sensors previously developed for USAF Research Laboratory (AFRL) plasma effects campaigns such as those aboard TacSat-2 in 2007 and AEHF-2 in 2012.

  17. Implementation of heaters on thermally actuated spacecraft mechanisms

    Science.gov (United States)

    Busch, John D.; Bokaie, Michael D.

    1994-01-01

    This paper presents general insight into the design and implementation of heaters as used in actuating mechanisms for spacecraft. Problems and considerations that were encountered during development of the Deep Space Probe and Science Experiment (DSPSE) solar array release mechanism are discussed. Obstacles included large expected fluctuations in ambient temperature, variations in voltage supply levels outgassing concerns, heater circuit design, materials selection, and power control options. Successful resolution of these issues helped to establish a methodology which can be applied to many of the heater design challenges found in thermally actuated mechanisms.

  18. A methodology to design heuristics for model selection based on the characteristics of data: Application to investigate when the Negative Binomial Lindley (NB-L) is preferred over the Negative Binomial (NB).

    Science.gov (United States)

    Shirazi, Mohammadali; Dhavala, Soma Sekhar; Lord, Dominique; Geedipally, Srinivas Reddy

    2017-10-01

    Safety analysts usually use post-modeling methods, such as the Goodness-of-Fit statistics or the Likelihood Ratio Test, to decide between two or more competitive distributions or models. Such metrics require all competitive distributions to be fitted to the data before any comparisons can be accomplished. Given the continuous growth in introducing new statistical distributions, choosing the best one using such post-modeling methods is not a trivial task, in addition to all theoretical or numerical issues the analyst may face during the analysis. Furthermore, and most importantly, these measures or tests do not provide any intuitions into why a specific distribution (or model) is preferred over another (Goodness-of-Logic). This paper ponders into these issues by proposing a methodology to design heuristics for Model Selection based on the characteristics of data, in terms of descriptive summary statistics, before fitting the models. The proposed methodology employs two analytic tools: (1) Monte-Carlo Simulations and (2) Machine Learning Classifiers, to design easy heuristics to predict the label of the 'most-likely-true' distribution for analyzing data. The proposed methodology was applied to investigate when the recently introduced Negative Binomial Lindley (NB-L) distribution is preferred over the Negative Binomial (NB) distribution. Heuristics were designed to select the 'most-likely-true' distribution between these two distributions, given a set of prescribed summary statistics of data. The proposed heuristics were successfully compared against classical tests for several real or observed datasets. Not only they are easy to use and do not need any post-modeling inputs, but also, using these heuristics, the analyst can attain useful information about why the NB-L is preferred over the NB - or vice versa- when modeling data. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. The Limit of Public Policy : Endogenous Preferences

    NARCIS (Netherlands)

    Bar-Gill, O.; Fershtman, C.

    2000-01-01

    In designing public policy it is not enough to consider the possible reaction of individuals to the chosen policy.Public policy may also affect the formation of preferences and norms in a society.The endogenous evolution of preferences, in addition to introducing a conceptual difficulty in

  20. The impact of the 2014 Ebola virus disease outbreak in Liberia on parent preferences for harsh discipline practices: a quasi-experimental, pre-post design.

    Science.gov (United States)

    Green, Eric; Chase, Rhea M; Zayzay, John; Finnegan, Amy; Puffer, Eve S

    2018-01-01

    This paper uses data from a cohort of parents and guardians of young children living in Monrovia, Liberia collected before and after the 2014 outbreak of Ebola virus disease (EVD) to estimate the impact of EVD exposure on implicit preferences for harsh discipline. We hypothesized that parents exposed to EVD-related sickness or death would exhibit a stronger preference for harsh discipline practices compared with non-exposed parents. The data for this analysis come from two survey rounds conducted in Liberia as part of an intervention trial of a behavioral parenting skills intervention. Following a baseline assessment of 201 enrolled parents in July 2014, all program and study activities were halted due to the outbreak of EVD. Following the EVD crisis, we conducted a tracking survey with parents who completed the baseline survey 12 months prior. In both rounds, we presented parents with 12 digital comic strips of a child misbehaving and asked them to indicate how they would react if they were the parent in the stories. Parents from households with reported EVD sickness or death became more 'harsh' (Glass's delta = 1.41) in their hypothetical decision-making compared with non-exposed parents, t (167)=-2.3, p   <  0.05. Parents from households that experienced EVD-related sickness or death not only reported significantly more household conflict and anxiety, but also reported that their child exhibited fewer difficulties. Results support the need for family-based interventions, including strategies to help parents learn alternatives to harsh punishment.

  1. Preferences over Social Risk

    DEFF Research Database (Denmark)

    Harrison, Glenn W.; Lau, Morten; Rutström, E. Elisabet

    2013-01-01

    that subjects systematically reveal different risk attitudes in a social setting with no prior knowledge about the risk preferences of others compared to when they solely bear the consequences of the decision. However, we also find that subjects are significantly more risk averse when they know the risk......We elicit individual preferences over social risk. We identify the extent to which these preferences are correlated with preferences over individual risk and the well-being of others. We examine these preferences in the context of laboratory experiments over small, anonymous groups, although...... the methodological issues extend to larger groups that form endogenously (e.g., families, committees, communities). Preferences over social risk can be closely approximated by individual risk attitudes when subjects have no information about the risk preferences of other group members. We find no evidence...

  2. Submarines, spacecraft and exhaled breath.

    Science.gov (United States)

    Pleil, Joachim D; Hansel, Armin

    2012-03-01

    Foreword The International Association of Breath Research (IABR) meetings are an eclectic gathering of researchers in the medical, environmental and instrumentation fields; our focus is on human health as assessed by the measurement and interpretation of trace chemicals in human exhaled breath. What may have escaped our notice is a complementary field of research that explores the creation and maintenance of artificial atmospheres practised by the submarine air monitoring and air purification (SAMAP) community. SAMAP is comprised of manufacturers, researchers and medical professionals dealing with the engineering and instrumentation to support human life in submarines and spacecraft (including shuttlecraft and manned rockets, high-altitude aircraft, and the International Space Station (ISS)). Here, the immediate concerns are short-term survival and long-term health in fairly confined environments where one cannot simply 'open the window' for fresh air. As such, one of the main concerns is air monitoring and the main sources of contamination are CO(2) and other constituents of human exhaled breath. Since the inaugural meeting in 1994 in Adelaide, Australia, SAMAP meetings have been held every two or three years alternating between the North American and European continents. The meetings are organized by Dr Wally Mazurek (a member of IABR) of the Defense Systems Technology Organization (DSTO) of Australia, and individual meetings are co-hosted by the navies of the countries in which they are held. An overriding focus at SAMAP is life support (oxygen availability and carbon dioxide removal). Certainly, other air constituents are also important; for example, the closed environment of a submarine or the ISS can build up contaminants from consumer products, cooking, refrigeration, accidental fires, propulsion and atmosphere maintenance. However, the most immediate concern is sustaining human metabolism: removing exhaled CO(2) and replacing metabolized O(2). Another

  3. Foot Pedals for Spacecraft Manual Control

    Science.gov (United States)

    Love, Stanley G.; Morin, Lee M.; McCabe, Mary

    2010-01-01

    Fifty years ago, NASA decided that the cockpit controls in spacecraft should be like the ones in airplanes. But controls based on the stick and rudder may not be best way to manually control a vehicle in space. A different method is based on submersible vehicles controlled with foot pedals. A new pilot can learn the sub's control scheme in minutes and drive it hands-free. We are building a pair of foot pedals for spacecraft control, and will test them in a spacecraft flight simulator.

  4. Electronic Systems for Spacecraft Vehicles: Required EDA Tools

    Science.gov (United States)

    Bachnak, Rafic

    1999-01-01

    The continuous increase in complexity of electronic systems is making the design and manufacturing of such systems more challenging than ever before. As a result, designers are finding it impossible to design efficient systems without the use of sophisticated Electronic Design Automation (EDA) tools. These tools offer integrated simulation of the electrical, mechanical, and manufacturing functions and lead to a correct by design methodology. This report identifies the EDA tools that would be needed to design, analyze, simulate, and evaluate electronic systems for spacecraft vehicles. In addition, the report presents recommendations to enhance the current JSC electronic design capabilities. This includes cost information and a discussion as to the impact, both positive and negative, of implementing the recommendations.

  5. Radioisotopic heater units warm an interplanetary spacecraft

    International Nuclear Information System (INIS)

    Franco-Ferreira, E.A.

    1998-01-01

    The Cassini orbiter and Huygens probe, which were successfully launched on October 15, 1997, constitute NASA's last grand-scale interplanetary mission of this century. The mission, which consists of a four-year, close-up study of Saturn and its moons, begins in July 2004 with Cassini's 60 orbits of Saturn and about 33 fly-bys of the large moon Titan. The Huygens probe will descend and land on Titan. Investigations will include Saturn's atmosphere, its rings and its magnetosphere. The atmosphere and surface of Titan and other icy moons also will be characterized. Because of the great distance of Saturn from the sun, some of the instruments and equipment on both the orbiter and the probe require external heaters to maintain their temperature within normal operating ranges. These requirements are met by Light Weight Radioisotope Heater Units (LWRHUs) designed, fabricated and safety tested at Los Alamos National Laboratory, New Mexico. An improved gas tungsten arc welding procedure lowered costs and decreased processing time for heat units for the Cassini spacecraft

  6. ADRC for spacecraft attitude and position synchronization in libration point orbits

    Science.gov (United States)

    Gao, Chen; Yuan, Jianping; Zhao, Yakun

    2018-04-01

    This paper addresses the problem of spacecraft attitude and position synchronization in libration point orbits between a leader and a follower. Using dual quaternion, the dimensionless relative coupled dynamical model is derived considering computation efficiency and accuracy. Then a model-independent dimensionless cascade pose-feedback active disturbance rejection controller is designed to spacecraft attitude and position tracking control problems considering parameter uncertainties and external disturbances. Numerical simulations for the final approach phase in spacecraft rendezvous and docking and formation flying are done, and the results show high-precision tracking errors and satisfactory convergent rates under bounded control torque and force which validate the proposed approach.

  7. Gaming Preferences of Aging Generations

    Science.gov (United States)

    Blocker, Kenneth A.; Wright, Timothy J.; Boot, Walter R.

    2017-01-01

    Increasing evidence suggests that action digital game training can improve a variety of perceptual and cognitive abilities, including those that decline most with age. Unfortunately, previous work has found that older adults dislike these games and adherence may be poor for action game-based interventions. The focus of the current study was to better understand the types of games older adults are willing to play and explore predictors of game preference (e.g., gender, age, technology experience, personality). With this information action games might be modified or developed to maximize adherence and cognitive benefit. Older adults were administered a modified version of an existing game questionnaire and a custom game preference survey. Clear preferences were observed that were similar between participants with and without previous digital game experience (with puzzle and intellectually stimulating games being most interesting to older adults in our sample, and massively multiplayer online games and first-person shooters being least interesting). Personality, demographic, and technology experience variables were also collected. Interesting trends suggested the possibility that several demographic and personality variables might be predictive of game preference. Results have implications for future directions of research, designing games that would appeal to older adult audiences, and for how to design custom games to maximize intervention adherence based on individual difference characteristics. PMID:29033699

  8. Gaming Preferences of Aging Generations.

    Science.gov (United States)

    Blocker, Kenneth A; Wright, Timothy J; Boot, Walter R

    2014-01-01

    Increasing evidence suggests that action digital game training can improve a variety of perceptual and cognitive abilities, including those that decline most with age. Unfortunately, previous work has found that older adults dislike these games and adherence may be poor for action game-based interventions. The focus of the current study was to better understand the types of games older adults are willing to play and explore predictors of game preference (e.g., gender, age, technology experience, personality). With this information action games might be modified or developed to maximize adherence and cognitive benefit. Older adults were administered a modified version of an existing game questionnaire and a custom game preference survey. Clear preferences were observed that were similar between participants with and without previous digital game experience (with puzzle and intellectually stimulating games being most interesting to older adults in our sample, and massively multiplayer online games and first-person shooters being least interesting). Personality, demographic, and technology experience variables were also collected. Interesting trends suggested the possibility that several demographic and personality variables might be predictive of game preference. Results have implications for future directions of research, designing games that would appeal to older adult audiences, and for how to design custom games to maximize intervention adherence based on individual difference characteristics.

  9. Assessment of the Use of Nanofluids in Spacecraft Active Thermal Control Systems

    Science.gov (United States)

    Ungar, Eugene K.; Erickson, Lisa R.

    2011-01-01

    The addition of metallic nanoparticles to a base heat transfer fluid can dramatically increase its thermal conductivity. These nanofluids have been shown to have advantages in some heat transport systems. Their enhanced properties can allow lower system volumetric flow rates and can reduce the required pumping power. Nanofluids have been suggested for use as working fluids for spacecraft Active Thermal Control Systems (ATCSs). However, there are no studies showing the end-to-end effect of nanofluids on the design and performance of spacecraft ATCSs. In the present work, a parametric study is performed to assess the use of nanofluids in a spacecraft ATCSs. The design parameters of the current Orion capsule and the tabulated thermophysical properties of nanofluids are used to assess the possible benefits of nanofluids and how their incorporation affects the overall design of a spacecraft ATCS. The study shows that the unique system and component-level design parameters of spacecraft ATCSs render them best suited for pure working fluids. The addition of nanoparticles to typical spacecraft thermal control working fluids actually results in an increase in the system mass and required pumping power.

  10. Relating MBSE to Spacecraft Development: A NASA Pathfinder

    Science.gov (United States)

    Othon, Bill

    2016-01-01

    The NASA Engineering and Safety Center (NESC) has sponsored a Pathfinder Study to investigate how Model Based Systems Engineering (MBSE) and Model Based Engineering (MBE) techniques can be applied by NASA spacecraft development projects. The objectives of this Pathfinder Study included analyzing both the products of the modeling activity, as well as the process and tool chain through which the spacecraft design activities are executed. Several aspects of MBSE methodology and process were explored. Adoption and consistent use of the MBSE methodology within an existing development environment can be difficult. The Pathfinder Team evaluated the possibility that an "MBSE Template" could be developed as both a teaching tool as well as a baseline from which future NASA projects could leverage. Elements of this template include spacecraft system component libraries, data dictionaries and ontology specifications, as well as software services that do work on the models themselves. The Pathfinder Study also evaluated the tool chain aspects of development. Two chains were considered: 1. The Development tool chain, through which SysML model development was performed and controlled, and 2. The Analysis tool chain, through which both static and dynamic system analysis is performed. Of particular interest was the ability to exchange data between SysML and other engineering tools such as CAD and Dynamic Simulation tools. For this study, the team selected a Mars Lander vehicle as the element to be designed. The paper will discuss what system models were developed, how data was captured and exchanged, and what analyses were conducted.

  11. Distributed Autonomous Control of Multiple Spacecraft During Close Proximity Operations

    National Research Council Canada - National Science Library

    McCamish, Shawn B

    2007-01-01

    This research contributes to multiple spacecraft control by developing an autonomous distributed control algorithm for close proximity operations of multiple spacecraft systems, including rendezvous...

  12. Spacecraft Swarm Coordination and Planning Tool, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Fractionated spacecraft architectures to distribute mission performance from a single, monolithic satellite across large number of smaller spacecraft, for missions...

  13. Singular formalism and admissible control of spacecraft with rotating flexible solar array

    Directory of Open Access Journals (Sweden)

    Lu Dongning

    2014-02-01

    Full Text Available This paper is concerned with the attitude control of a three-axis-stabilized spacecraft which consists of a central rigid body and a flexible sun-tracking solar array driven by a solar array drive assembly. Based on the linearization of the dynamics of the spacecraft and the modal identities about the flexible and rigid coupling matrices, the spacecraft attitude dynamics is reduced to a formally singular system with periodically varying parameters, which is quite different from a spacecraft with fixed appendages. In the framework of the singular control theory, the regularity and impulse-freeness of the singular system is analyzed and then admissible attitude controllers are designed by Lyapunov’s method. To improve the robustness against system uncertainties, an H∞ optimal control is designed by optimizing the H∞ norm of the system transfer function matrix. Comparative numerical experiments are performed to verify the theoretical results.

  14. Spacecraft Cabin Particulate Monitor, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — We have built and tested an optical extinction monitor for the detection of spacecraft cabin particulates. This sensor sensitive to particle sizes ranging from a few...

  15. Computational Model for Spacecraft/Habitat Volume

    Data.gov (United States)

    National Aeronautics and Space Administration — Please note that funding to Dr. Simon Hsiang, a critical co-investigator for the development of the Spacecraft Optimization Layout and Volume (SOLV) model, was...

  16. Industry perspectives on Plug-& -Play Spacecraft Avionics

    Science.gov (United States)

    Franck, R.; Graven, P.; Liptak, L.

    This paper describes the methodologies and findings from an industry survey of awareness and utility of Spacecraft Plug-& -Play Avionics (SPA). The survey was conducted via interviews, in-person and teleconference, with spacecraft prime contractors and suppliers. It focuses primarily on AFRL's SPA technology development activities but also explores the broader applicability and utility of Plug-& -Play (PnP) architectures for spacecraft. Interviews include large and small suppliers as well as large and small spacecraft prime contractors. Through these “ product marketing” interviews, awareness and attitudes can be assessed, key technical and market barriers can be identified, and opportunities for improvement can be uncovered. Although this effort focuses on a high-level assessment, similar processes can be used to develop business cases and economic models which may be necessary to support investment decisions.

  17. Investigation of nickel hydrogen battery technology for the RADARSAT spacecraft

    Science.gov (United States)

    Mccoy, D. A.; Lackner, J. L.

    1986-01-01

    The low Earth orbit (LEO) operations of the RADARSAT spacecraft require high performance batteries to provide energy to the payload and platform during eclipse period. Nickel Hydrogen cells are currently competing with the more traditional Nickel Cadmium cells for high performance spacecraft applications at geostationary Earth orbit (GEO) and Leo. Nickel Hydrogen cells appear better suited for high power applications where high currents and high Depths of Discharge are required. Although a number of GEO missions have flown with Nickel Hydrogen batteries, it is not readily apparent that the LEO version of the Nickel Hydrogen cell is able to withstand the extended cycle lifetime (5 years) of the RADARSAT mission. The problems associated with Nickel Hydrogen cells are discussed in the contex of RADARSAT mission and a test program designed to characterize cell performance is presented.

  18. Miniaturized star tracker for micro spacecraft with high angular rate

    Science.gov (United States)

    Li, Jianhua; Li, Zhifeng; Niu, Zhenhong; Liu, Jiaqi

    2017-10-01

    There is a clear need for miniaturized, lightweight, accurate and inexpensive star tracker for spacecraft with large anglar rate. To face these new constraints, the Beijing Institute of Space Long March Vehicle has designed, built and flown a low cost miniaturized star tracker that provides autonomous ("Lost in Space") inertial attitude determination, 2 Hz 3-axis star tracking, and digital imaging with embedded compression. Detector with high sensitivity is adopted to meet the dynamic and miniature requirement. A Sun and Moon avoiding method based on the calculation of Sun and Moon's vector by astronomical theory is proposed. The produced prototype weight 0.84kg, and can be used for a spacecraft with 6°/s anglar rate. The average angle measure error is less than 43 arc second. The ground verification and application of the star tracker during the pick-up flight test showed that the capability of the product meet the requirement.

  19. Dream missions space colonies, nuclear spacecraft and other possibilities

    CERN Document Server

    van Pelt, Michel

    2017-01-01

    This book takes the reader on a journey through the history of extremely ambitious, large and complex space missions that never happened. What were the dreams and expectations of the visionaries behind these plans, and why were they not successful in bringing their projects to reality thus far? As spaceflight development progressed, new technologies and ideas led to pushing the boundaries of engineering and technology though still grounded in real scientific possibilities. Examples are space colonies, nuclear-propelled interplanetary spacecraft, space telescopes consisting of multiple satellites and canon launch systems. Each project described in this book says something about the dreams and expectations of their time, and their demise was often linked to an important change in the cultural, political and social state of the world. For each mission or spacecraft concept, the following will be covered: • Description of the design. • Overview of the history of the concept and the people involved. • Why it...

  20. 3D Reconfigurable MPSoC for Unmanned Spacecraft Navigation

    Science.gov (United States)

    Dekoulis, George

    2016-07-01

    This paper describes the design of a new lightweight spacecraft navigation system for unmanned space missions. The system addresses the demands for more efficient autonomous navigation in the near-Earth environment or deep space. The proposed instrumentation is directly suitable for unmanned systems operation and testing of new airborne prototypes for remote sensing applications. The system features a new sensor technology and significant improvements over existing solutions. Fluxgate type sensors have been traditionally used in unmanned defense systems such as target drones, guided missiles, rockets and satellites, however, the guidance sensors' configurations exhibit lower specifications than the presented solution. The current implementation is based on a recently developed material in a reengineered optimum sensor configuration for unprecedented low-power consumption. The new sensor's performance characteristics qualify it for spacecraft navigation applications. A major advantage of the system is the efficiency in redundancy reduction achieved in terms of both hardware and software requirements.

  1. Formation of disintegration particles in spacecraft recorders

    International Nuclear Information System (INIS)

    Kurnosova, L.V.; Fradkin, M.I.; Razorenov, L.A.

    1986-01-01

    Experiments performed on the spacecraft Salyut 1, Kosmos 410, and Kosmos 443 enable us to record the disintegration products of particles which are formed in the material of the detectors on board the spacecraft. The observations were made by means of a delayed coincidence method. We have detected a meson component and also a component which is apparently associated with the generation of radioactive isotopes in the detectors

  2. Power requirements for commercial communications spacecraft

    Science.gov (United States)

    Billerbeck, W. J.

    1985-01-01

    Historical data on commercial spacecraft power systems are presented and their power requirements to the growth of satellite communications channel usage are related. Some approaches for estimating future power requirements of this class of spacecraft through the year 2000 are proposed. The key technology drivers in satellite power systems are addressed. Several technological trends in such systems are described, focusing on the most useful areas for research and development of major subsystems, including solar arrays, energy storage, and power electronics equipment.

  3. Standardizing the information architecture for spacecraft operations

    Science.gov (United States)

    Easton, C. R.

    1994-01-01

    This paper presents an information architecture developed for the Space Station Freedom as a model from which to derive an information architecture standard for advanced spacecraft. The information architecture provides a way of making information available across a program, and among programs, assuming that the information will be in a variety of local formats, structures and representations. It provides a format that can be expanded to define all of the physical and logical elements that make up a program, add definitions as required, and import definitions from prior programs to a new program. It allows a spacecraft and its control center to work in different representations and formats, with the potential for supporting existing spacecraft from new control centers. It supports a common view of data and control of all spacecraft, regardless of their own internal view of their data and control characteristics, and of their communications standards, protocols and formats. This information architecture is central to standardizing spacecraft operations, in that it provides a basis for information transfer and translation, such that diverse spacecraft can be monitored and controlled in a common way.

  4. Attitude Estimation in Fractionated Spacecraft Cluster Systems

    Science.gov (United States)

    Hadaegh, Fred Y.; Blackmore, James C.

    2011-01-01

    An attitude estimation was examined in fractioned free-flying spacecraft. Instead of a single, monolithic spacecraft, a fractionated free-flying spacecraft uses multiple spacecraft modules. These modules are connected only through wireless communication links and, potentially, wireless power links. The key advantage of this concept is the ability to respond to uncertainty. For example, if a single spacecraft module in the cluster fails, a new one can be launched at a lower cost and risk than would be incurred with onorbit servicing or replacement of the monolithic spacecraft. In order to create such a system, however, it is essential to know what the navigation capabilities of the fractionated system are as a function of the capabilities of the individual modules, and to have an algorithm that can perform estimation of the attitudes and relative positions of the modules with fractionated sensing capabilities. Looking specifically at fractionated attitude estimation with startrackers and optical relative attitude sensors, a set of mathematical tools has been developed that specify the set of sensors necessary to ensure that the attitude of the entire cluster ( cluster attitude ) can be observed. Also developed was a navigation filter that can estimate the cluster attitude if these conditions are satisfied. Each module in the cluster may have either a startracker, a relative attitude sensor, or both. An extended Kalman filter can be used to estimate the attitude of all modules. A range of estimation performances can be achieved depending on the sensors used and the topology of the sensing network.

  5. Modeling and Analysis of Realistic Fire Scenarios in Spacecraft

    Science.gov (United States)

    Brooker, J. E.; Dietrich, D. L.; Gokoglu, S. A.; Urban, D. L.; Ruff, G. A.

    2015-01-01

    An accidental fire inside a spacecraft is an unlikely, but very real emergency situation that can easily have dire consequences. While much has been learned over the past 25+ years of dedicated research on flame behavior in microgravity, a quantitative understanding of the initiation, spread, detection and extinguishment of a realistic fire aboard a spacecraft is lacking. Virtually all combustion experiments in microgravity have been small-scale, by necessity (hardware limitations in ground-based facilities and safety concerns in space-based facilities). Large-scale, realistic fire experiments are unlikely for the foreseeable future (unlike in terrestrial situations). Therefore, NASA will have to rely on scale modeling, extrapolation of small-scale experiments and detailed numerical modeling to provide the data necessary for vehicle and safety system design. This paper presents the results of parallel efforts to better model the initiation, spread, detection and extinguishment of fires aboard spacecraft. The first is a detailed numerical model using the freely available Fire Dynamics Simulator (FDS). FDS is a CFD code that numerically solves a large eddy simulation form of the Navier-Stokes equations. FDS provides a detailed treatment of the smoke and energy transport from a fire. The simulations provide a wealth of information, but are computationally intensive and not suitable for parametric studies where the detailed treatment of the mass and energy transport are unnecessary. The second path extends a model previously documented at ICES meetings that attempted to predict maximum survivable fires aboard space-craft. This one-dimensional model implies the heat and mass transfer as well as toxic species production from a fire. These simplifications result in a code that is faster and more suitable for parametric studies (having already been used to help in the hatch design of the Multi-Purpose Crew Vehicle, MPCV).

  6. Development of an advanced spacecraft tandem mass spectrometer

    Science.gov (United States)

    Drew, Russell C.

    1992-03-01

    The purpose of this research was to apply current advanced technology in electronics and materials to the development of a miniaturized Tandem Mass Spectrometer that would have the potential for future development into a package suitable for spacecraft use. The mass spectrometer to be used as a basis for the tandem instrument would be a magnetic sector instrument, of Nier-Johnson configuration, as used on the Viking Mars Lander mission. This instrument configuration would then be matched with a suitable second stage MS to provide the benefits of tandem MS operation for rapid identification of unknown organic compounds. This tandem instrument is configured with a newly designed GC system to aid in separation of complex mixtures prior to MS analysis. A number of important results were achieved in the course of this project. Among them were the development of a miniaturized GC subsystem, with a unique desorber-injector, fully temperature feedback controlled oven with powered cooling for rapid reset to ambient conditions, a unique combination inlet system to the MS that provides for both membrane sampling and direct capillary column sample transfer, a compact and ruggedized alignment configuration for the MS, an improved ion source design for increased sensitivity, and a simple, rugged tandem MS configuration that is particularly adaptable to spacecraft use because of its low power and low vacuum pumping requirements. The potential applications of this research include use in manned spacecraft like the space station as a real-time detection and warning device for the presence of potentially harmful trace contaminants of the spacecraft atmosphere, use as an analytical device for evaluating samples collected on the Moon or a planetary surface, or even use in connection with monitoring potentially hazardous conditions that may exist in terrestrial locations such as launch pads, environmental test chambers or other sensitive areas. Commercial development of the technology

  7. Robustness and Actuator Bandwidth of MRP-Based Sliding Mode Control for Spacecraft Attitude Control Problems

    Science.gov (United States)

    Keum, Jung-Hoon; Ra, Sung-Woong

    2009-12-01

    Nonlinear sliding surface design in variable structure systems for spacecraft attitude control problems is studied. A robustness analysis is performed for regular form of system, and calculation of actuator bandwidth is presented by reviewing sliding surface dynamics. To achieve non-singular attitude description and minimal parameterization, spacecraft attitude control problems are considered based on modified Rodrigues parameters (MRP). It is shown that the derived controller ensures the sliding motion in pre-determined region irrespective of unmodeled effects and disturbances.

  8. Chattering-Free Adaptive Sliding Mode Control for Attitude Tracking of Spacecraft with External Disturbance

    Directory of Open Access Journals (Sweden)

    Xuxi Zhang

    2014-01-01

    Full Text Available The attitude tracking problem of spacecraft in the presence of unknown disturbance is investigated. By using the adaptive control technique and the Lyapunov stability theory, a chattering-free adaptive sliding mode control law is proposed for the attitude tracking problem of spacecraft with unknown disturbance. Simulation results are employed to demonstrate the effectiveness of the proposed control design technique in this paper.

  9. Development of Star Tracker System for Accurate Estimation of Spacecraft Attitude

    Science.gov (United States)

    2009-12-01

    For a high- cost spacecraft with accurate pointing requirements, the use of a star tracker is the preferred method for attitude determination. The...solutions, however there are certain costs with using this algorithm. There are significantly more features a triangle can provide when compared to an...to the other. The non-rotating geocentric equatorial frame provides an inertial frame for the two-body problem of a satellite in orbit. In this

  10. Compatibility of Mating Preferences

    OpenAIRE

    Bingol, Haluk O.; Basar, Omer

    2016-01-01

    Human mating is a complex phenomenon. Although men and women have different preferences in mate selection, there should be compatibility in these preferences since human mating requires agreement of both parties. We investigate how compatible the mating preferences of men and women are in a given property such as age, height, education and income. We use dataset of a large online dating site (N = 44, 255 users). (i) Our findings are based on the "actual behavior" of users trying to find a dat...

  11. Global Precipitation Measurement (GPM) Mission Core Spacecraft Systems Engineering Challenges

    Science.gov (United States)

    Bundas, David J.; ONeill, Deborah; Field, Thomas; Meadows, Gary; Patterson, Peter

    2006-01-01

    The Global Precipitation Measurement (GPM) Mission is a collaboration between the National Aeronautics and Space Administration (NASA) and the Japanese Aerospace Exploration Agency (JAXA), and other US and international partners, with the goal of monitoring the diurnal and seasonal variations in precipitation over the surface of the earth. These measurements will be used to improve current climate models and weather forecasting, and enable improved storm and flood warnings. This paper gives an overview of the mission architecture and addresses the status of some key trade studies, including the geolocation budgeting, design considerations for spacecraft charging, and design issues related to the mitigation of orbital debris.

  12. Demonstrating the Safety and Reliability of a New System or Spacecraft: Incorporating Analyses and Reviews of the Design and Processing in Determining the Number of Tests to be Conducted

    Science.gov (United States)

    Vesely, William E.; Colon, Alfredo E.

    2010-01-01

    Design Safety/Reliability is associated with the probability of no failure-causing faults existing in a design. Confidence in the non-existence of failure-causing faults is increased by performing tests with no failure. Reliability-Growth testing requirements are based on initial assurance and fault detection probability. Using binomial tables generally gives too many required tests compared to reliability-growth requirements. Reliability-Growth testing requirements are based on reliability principles and factors and should be used.

  13. Particle Morphology and Elemental Composition of Smoke Generated by Overheating Common Spacecraft Materials

    Science.gov (United States)

    Meyer, Marit E.

    2015-01-01

    Fire safety in the indoor spacecraft environment is concerned with a unique set of fuels which are designed to not combust. Unlike terrestrial flaming fires, which often can consume an abundance of wood, paper and cloth, spacecraft fires are expected to be generated from overheating electronics consisting of flame resistant materials. Therefore, NASA prioritizes fire characterization research for these fuels undergoing oxidative pyrolysis in order to improve spacecraft fire detector design. A thermal precipitator designed and built for spacecraft fire safety test campaigns at the NASA White Sands Test Facility (WSTF) successfully collected an abundance of smoke particles from oxidative pyrolysis. A thorough microscopic characterization has been performed for ten types of smoke from common spacecraft materials or mixed materials heated at multiple temperatures using the following techniques: SEM, TEM, high resolution TEM, high resolution STEM and EDS. Resulting smoke particle morphologies and elemental compositions have been observed which are consistent with known thermal decomposition mechanisms in the literature and chemical make-up of the spacecraft fuels. Some conclusions about particle formation mechanisms are explored based on images of the microstructure of Teflon smoke particles and tar ball-like particles from Nomex fabric smoke.

  14. Thrusting maneuver control of a small spacecraft via only gimbaled-thruster scheme

    Science.gov (United States)

    Kabganian, Mansour; Kouhi, Hamed; Shahravi, Morteza; Fani Saberi, Farhad

    2018-05-01

    The thrust vector control (TVC) scheme is a powerful method in spacecraft attitude control. Since the control of a small spacecraft is being studied here, a solid rocket motor (SRM) should be used instead of a liquid propellant motor. Among the TVC methods, gimbaled-TVC as an efficient method is employed in this paper. The spacecraft structure is composed of a body and a gimbaled-SRM where common attitude control systems such as reaction control system (RCS) and spin-stabilization are not presented. A nonlinear two-body model is considered for the characterization of the gimbaled-thruster spacecraft where, the only control input is provided by a gimbal actuator. The attitude of the spacecraft is affected by a large exogenous disturbance torque which is generated by a thrust vector misalignment from the center of mass (C.M). A linear control law is designed to stabilize the spacecraft attitude while rejecting the mentioned disturbance torque. A semi-analytical formulation of the region of attraction (RoA) is developed to ensure the local stability and fast convergence of the nonlinear closed-loop system. Simulation results of the 3D maneuvers are included to show the applicability of this method for use in a small spacecraft.

  15. Spacecraft Hybrid (Mixed-Actuator) Attitude Control Experiences on NASA Science Missions

    Science.gov (United States)

    Dennehy, Cornelius J.

    2014-01-01

    There is a heightened interest within NASA for the design, development, and flight implementation of mixed-actuator hybrid attitude control systems for science spacecraft that have less than three functional reaction wheel actuators. This interest is driven by a number of recent reaction wheel failures on aging, but what could be still scientifically productive, NASA spacecraft if a successful hybrid attitude control mode can be implemented. Over the years, hybrid (mixed-actuator) control has been employed for contingency attitude control purposes on several NASA science mission spacecraft. This paper provides a historical perspective of NASA's previous engineering work on spacecraft mixed-actuator hybrid control approaches. An update of the current situation will also be provided emphasizing why NASA is now so interested in hybrid control. The results of the NASA Spacecraft Hybrid Attitude Control Workshop, held in April of 2013, will be highlighted. In particular, the lessons learned captured from that workshop will be shared in this paper. An update on the most recent experiences with hybrid control on the Kepler spacecraft will also be provided. This paper will close with some future considerations for hybrid spacecraft control.

  16. Navigating the MESSENGER Spacecraft through End of Mission

    Science.gov (United States)

    Bryan, C. G.; Williams, B. G.; Williams, K. E.; Taylor, A. H.; Carranza, E.; Page, B. R.; Stanbridge, D. R.; Mazarico, E.; Neumann, G. A.; O'Shaughnessy, D. J.; McAdams, J. V.; Calloway, A. B.

    2015-12-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft orbited the planet Mercury from March 2011 until the end of April 2015, when it impacted the planetary surface after propellant reserves used to maintain the orbit were depleted. This highly successful mission was led by the principal investigator, Sean C. Solomon, of Columbia University. The Johns Hopkins University Applied Physics Laboratory (JHU/APL) designed and assembled the spacecraft and served as the home for spacecraft operations. Spacecraft navigation for the entirety of the mission was provided by the Space Navigation and Flight Dynamics Practice (SNAFD) of KinetX Aerospace. Orbit determination (OD) solutions were generated through processing of radiometric tracking data provided by NASA's Deep Space Network (DSN) using the MIRAGE suite of orbital analysis tools. The MESSENGER orbit was highly eccentric, with periapsis at a high northern latitude and periapsis altitude in the range 200-500 km for most of the orbital mission phase. In a low-altitude "hover campaign" during the final two months of the mission, periapsis altitudes were maintained within a narrow range between about 35 km and 5 km. Navigating a spacecraft so near a planetary surface presented special challenges. Tasks required to meet those challenges included the modeling and estimation of Mercury's gravity field and of solar and planetary radiation pressure, and the design of frequent orbit-correction maneuvers. Superior solar conjunction also presented observational modeling issues. One key to the overall success of the low-altitude hover campaign was a strategy to utilize data from an onboard laser altimeter as a cross-check on the navigation team's reconstructed and predicted estimates of periapsis altitude. Data obtained from the Mercury Laser Altimeter (MLA) on a daily basis provided near-real-time feedback that proved invaluable in evaluating alternative orbit estimation strategies, and

  17. Probabilistic Risk Assessment for Decision Making During Spacecraft Operations

    Science.gov (United States)

    Meshkat, Leila

    2009-01-01

    Decisions made during the operational phase of a space mission often have significant and immediate consequences. Without the explicit consideration of the risks involved and their representation in a solid model, it is very likely that these risks are not considered systematically in trade studies. Wrong decisions during the operational phase of a space mission can lead to immediate system failure whereas correct decisions can help recover the system even from faulty conditions. A problem of special interest is the determination of the system fault protection strategies upon the occurrence of faults within the system. Decisions regarding the fault protection strategy also heavily rely on a correct understanding of the state of the system and an integrated risk model that represents the various possible scenarios and their respective likelihoods. Probabilistic Risk Assessment (PRA) modeling is applicable to the full lifecycle of a space mission project, from concept development to preliminary design, detailed design, development and operations. The benefits and utilities of the model, however, depend on the phase of the mission for which it is used. This is because of the difference in the key strategic decisions that support each mission phase. The focus of this paper is on describing the particular methods used for PRA modeling during the operational phase of a spacecraft by gleaning insight from recently conducted case studies on two operational Mars orbiters. During operations, the key decisions relate to the commands sent to the spacecraft for any kind of diagnostics, anomaly resolution, trajectory changes, or planning. Often, faults and failures occur in the parts of the spacecraft but are contained or mitigated before they can cause serious damage. The failure behavior of the system during operations provides valuable data for updating and adjusting the related PRA models that are built primarily based on historical failure data. The PRA models, in turn

  18. Eye tracking social preferences

    NARCIS (Netherlands)

    Jiang, Ting; Potters, Jan; Funaki, Yukihiko

    We hypothesize that if people are motivated by a particular social preference, then choosing in accordance with this preference will lead to an identifiable pattern of eye movements. We track eye movements while subjects make choices in simple three-person distribution experiments. We characterize

  19. von Neumann Morgenstern Preferences

    DEFF Research Database (Denmark)

    Vind, Karl

    von Neumann Morgenstern utility is generalized to von Neumann Morgenstern preferences. The proof is an application of simple hyperplane theorems......von Neumann Morgenstern utility is generalized to von Neumann Morgenstern preferences. The proof is an application of simple hyperplane theorems...

  20. von Neumann Morgenstern Preferences

    DEFF Research Database (Denmark)

    Vind, Karl

    2000-01-01

    von Neumann Morgenstern utility is generalized to von Neumann Morgenstern preferences. The proof is an application of simple hyperplane theorems......von Neumann Morgenstern utility is generalized to von Neumann Morgenstern preferences. The proof is an application of simple hyperplane theorems...

  1. Measuring Normative Risk Preferences

    NARCIS (Netherlands)

    G.A.G. Alserda (Gosse)

    2017-01-01

    textabstractThe results of eliciting risk preferences depend on the elicitation method. Different methods of measuring the same variable tend to produce different results. This raises the question whether normative risk preferences can be elicited at all. Using two types of manipulation, I assess

  2. On TTEthernet for Integrated Fault-Tolerant Spacecraft Networks

    Science.gov (United States)

    Loveless, Andrew

    2015-01-01

    There has recently been a push for adopting integrated modular avionics (IMA) principles in designing spacecraft architectures. This consolidation of multiple vehicle functions to shared computing platforms can significantly reduce spacecraft cost, weight, and de- sign complexity. Ethernet technology is attractive for inclusion in more integrated avionic systems due to its high speed, flexibility, and the availability of inexpensive commercial off-the-shelf (COTS) components. Furthermore, Ethernet can be augmented with a variety of quality of service (QoS) enhancements that enable its use for transmitting critical data. TTEthernet introduces a decentralized clock synchronization paradigm enabling the use of time-triggered Ethernet messaging appropriate for hard real-time applications. TTEthernet can also provide two forms of event-driven communication, therefore accommodating the full spectrum of traffic criticality levels required in IMA architectures. This paper explores the application of TTEthernet technology to future IMA spacecraft architectures as part of the Avionics and Software (A&S) project chartered by NASA's Advanced Exploration Systems (AES) program.

  3. Adaptive Management of Computing and Network Resources for Spacecraft Systems

    Science.gov (United States)

    Pfarr, Barbara; Welch, Lonnie R.; Detter, Ryan; Tjaden, Brett; Huh, Eui-Nam; Szczur, Martha R. (Technical Monitor)

    2000-01-01

    It is likely that NASA's future spacecraft systems will consist of distributed processes which will handle dynamically varying workloads in response to perceived scientific events, the spacecraft environment, spacecraft anomalies and user commands. Since all situations and possible uses of sensors cannot be anticipated during pre-deployment phases, an approach for dynamically adapting the allocation of distributed computational and communication resources is needed. To address this, we are evolving the DeSiDeRaTa adaptive resource management approach to enable reconfigurable ground and space information systems. The DeSiDeRaTa approach embodies a set of middleware mechanisms for adapting resource allocations, and a framework for reasoning about the real-time performance of distributed application systems. The framework and middleware will be extended to accommodate (1) the dynamic aspects of intra-constellation network topologies, and (2) the complete real-time path from the instrument to the user. We are developing a ground-based testbed that will enable NASA to perform early evaluation of adaptive resource management techniques without the expense of first deploying them in space. The benefits of the proposed effort are numerous, including the ability to use sensors in new ways not anticipated at design time; the production of information technology that ties the sensor web together; the accommodation of greater numbers of missions with fewer resources; and the opportunity to leverage the DeSiDeRaTa project's expertise, infrastructure and models for adaptive resource management for distributed real-time systems.

  4. SpaceX's Dragon America's next generation spacecraft

    CERN Document Server

    Seedhouse, Erik

    2016-01-01

    This book describes Dragon V2, a futuristic vehicle that not only provides a means for NASA to transport its astronauts to the orbiting outpost but also advances SpaceX’s core objective of reusability. A direct descendant of Dragon, Dragon V2 can be retrieved, refurbished and re-launched. It is a spacecraft with the potential to completely revolutionize the economics of an industry where equipment costing hundreds of millions of dollars is routinely discarded after a single use. It was presented by SpaceX CEO Elon Musk in May 2014 as the spaceship that will carry NASA astronauts to the International Space Station as soon as 2016 SpaceX’s Dragon – America’s Next Generation Spacecraft describes the extraordinary feats of engineering and human achievement that have placed this revolutionary spacecraft at the forefront of the launch industry and positioned it as the precursor for ultimately transporting humans to Mars. It describes the design and development of Dragon, provides mission highlights of the f...

  5. Spacecraft Architecture and environmental pshychology

    Science.gov (United States)

    Ören, Ayşe

    2016-07-01

    As we embark on a journey for new homes in the new worlds to lay solid foundations, we should consider not only the survival of frontiers but also well-being of those to live in zero gravity. As a versatile science, architecture encompasses abstract human needs as well. On our new different direction in the course of the Homo sapiens evolution, we can do this with designs addressing both our needs and senses. Well-being of humans can be achieved by creating environments supporting the cognitive and social stages in the evolution process. Space stations are going through their own evolution process. Any step taken can serve as a reference for further attempts. When studying the history of architecture, window designing is discussed in a later phase, which is the case for building a spaceship as well. We lean on the places we live both physically and metaphorically. The feeling of belonging is essential here, entailing trans-humanism, which is significant since the environment therein is like a dress comfortable enough to fit in, meeting needs without any burden. Utilizing the advent of technology, we can create moods and atmospheres to regulate night and day cycles, thus we can turn claustrophobic places into cozy or dream-like places. Senses provoke a psychological sensation going beyond cultural codes as they are rooted within consciousness, which allows designers to create a mood within a space that tells a story and evokes an emotional impact. Color, amount of light, sound and odor are not superficial. As much as intangible, they are real and powerful tools with a physical presence. Tapping into induction, we can solve a whole system based on a part thereof. Therefore, fractal designs may not yield good results unless used correctly in terms of design although they are functional, which makes geometric arrangement critical.

  6. Spacecraft Architecture and well being

    Science.gov (United States)

    Ören, Ayşe

    2016-07-01

    As we embark on a journey for new homes in the new worlds to lay solid foundations, we should consider not only the survival of frontiers but also well-being of those to live in zero gravity. As a versatile science, architecture encompasses abstract human needs as well. On our new different direction in the course of the Homo sapiens evolution, we can do this with designs addressing both our needs and senses. Well-being of humans can be achieved by creating environments supporting the cognitive and social stages in the evolution process. Space stations are going through their own evolution process. Any step taken can serve as a reference for further attempts. When studying the history of architecture, window designing is discussed in a later phase, which is the case for building a spaceship as well. We lean on the places we live both physically and metaphorically. The feeling of belonging is essential here, entailing trans-humanism, which is significant since the environment therein is like a dress comfortable enough to fit in, meeting needs without any burden. Utilizing the advent of technology, we can create moods and atmospheres to regulate night and day cycles, thus we can turn claustrophobic places into cozy or dream-like places. Senses provoke a psychological sensation going beyond cultural codes as they are rooted within consciousness, which allows designers to create a mood within a space that tells a story and evokes an emotional impact. Color, amount of light, sound and odor are not superficial. As much as intangible, they are real and powerful tools with a physical presence. Tapping into induction, we can solve a whole system based on a part thereof. Therefore, fractal designs may not yield good results unless used correctly in terms of design although they are functional, which makes geometric arrangement critical.

  7. Hybrid spacecraft attitude control system

    OpenAIRE

    Renuganth Varatharajoo; Ramly Ajir; Tamizi Ahmad

    2016-01-01

    The hybrid subsystem design could be an attractive approach for futurespacecraft to cope with their demands. The idea of combining theconventional Attitude Control System and the Electrical Power System ispresented in this article. The Combined Energy and Attitude ControlSystem (CEACS) consisting of a double counter rotating flywheel assemblyis investigated for small satellites in this article. Another hybrid systemincorporating the conventional Attitude Control System into the ThermalControl...

  8. Manned spacecraft automation and robotics

    Science.gov (United States)

    Erickson, Jon D.

    1987-01-01

    The Space Station holds promise of being a showcase user and driver of advanced automation and robotics technology. The author addresses the advances in automation and robotics from the Space Shuttle - with its high-reliability redundancy management and fault tolerance design and its remote manipulator system - to the projected knowledge-based systems for monitoring, control, fault diagnosis, planning, and scheduling, and the telerobotic systems of the future Space Station.

  9. Global Precipitation Measurement (GPM) Spacecraft Lithium Ion Battery Micro-Cycling Investigation

    Science.gov (United States)

    Dakermanji, George; Lee, Leonine; Spitzer, Thomas

    2016-01-01

    The Global Precipitation Measurement (GPM) spacecraft was jointly developed by NASA and JAXA. It is a Low Earth Orbit (LEO) spacecraft launched on February 27, 2014. The power system is a Direct Energy Transfer (DET) system designed to support 1950 watts orbit average power. The batteries use SONY 18650HC cells and consist of three 8s by 84p batteries operated in parallel as a single battery. During instrument integration with the spacecraft, large current transients were observed in the battery. Investigation into the matter traced the cause to the Dual-Frequency Precipitation Radar (DPR) phased array radar which generates cyclical high rate current transients on the spacecraft power bus. The power system electronics interaction with these transients resulted in the current transients in the battery. An accelerated test program was developed to bound the effect, and to assess the impact to the mission.

  10. A historical overview of the electrical power systems in the US manned and some US unmanned spacecraft

    Science.gov (United States)

    Maisel, J. E.

    1984-01-01

    A historical overview of electrical power systems used in the U.S. manned spacecraft and some of the U.S. unmanned spacecraft is presented in this investigation. A time frame of approximately 25 years, the period for 1959 to 1984, is covered in this report. Results indicate that the nominal bus voltage was 28 volts dc in most spacecraft and all other voltage levels were derived from this voltage through such techniques as voltage inversion or rectification, or a combination. Most spacecraft used solar arrays for the main source of power except for those spacecraft that had a relatively short flight duration, or deep spaceprobes that were designed for very long flight duration. Fuel cells were used on Gemini, Apollo, and Space Shuttle (short duration flights) while radioisotope thermoelectric generators were employed on the Pioneer, Jupiter/Saturn, Viking Lander, and Voyager spacecraft (long duration flights). The main dc bus voltage was unregulated on the manned spacecraft with voltage regulation provided at the user loads. A combination of regulated, semiregulated, and unregulated buses were used on the unmanned spacecraft depending on the type of load. For example, scientific instruments were usually connected to regulated buses while fans, relays, etc. were energized from an unregulated bus. Different forms of voltage regulation, such as shunt, buck/boot, and pulse-width modulated regulators, were used. This report includes a comprehensive bibliography on spacecraft electrical power systems for the space programs investigated.

  11. The Association between Learning Preferences and Preferred Methods of Assessment of Dental Students

    Science.gov (United States)

    Buchanan, Phil

    2016-01-01

    This study is designed to gather information concerning a possible relationship between how dental students prefer to take in and communicate new information and how they prefer to be assessed. Though there are numerous references in the literature regarding the learning styles of students there are also references to the inaccuracy of such…

  12. Algorithms for Learning Preferences for Sets of Objects

    Science.gov (United States)

    Wagstaff, Kiri L.; desJardins, Marie; Eaton, Eric

    2010-01-01

    A method is being developed that provides for an artificial-intelligence system to learn a user's preferences for sets of objects and to thereafter automatically select subsets of objects according to those preferences. The method was originally intended to enable automated selection, from among large sets of images acquired by instruments aboard spacecraft, of image subsets considered to be scientifically valuable enough to justify use of limited communication resources for transmission to Earth. The method is also applicable to other sets of objects: examples of sets of objects considered in the development of the method include food menus, radio-station music playlists, and assortments of colored blocks for creating mosaics. The method does not require the user to perform the often-difficult task of quantitatively specifying preferences; instead, the user provides examples of preferred sets of objects. This method goes beyond related prior artificial-intelligence methods for learning which individual items are preferred by the user: this method supports a concept of setbased preferences, which include not only preferences for individual items but also preferences regarding types and degrees of diversity of items in a set. Consideration of diversity in this method involves recognition that members of a set may interact with each other in the sense that when considered together, they may be regarded as being complementary, redundant, or incompatible to various degrees. The effects of such interactions are loosely summarized in the term portfolio effect. The learning method relies on a preference representation language, denoted DD-PREF, to express set-based preferences. In DD-PREF, a preference is represented by a tuple that includes quality (depth) functions to estimate how desired a specific value is, weights for each feature preference, the desired diversity of feature values, and the relative importance of diversity versus depth. The system applies statistical

  13. Depression Treatment Preferences in Older Primary Care Patients

    Science.gov (United States)

    Gum, Amber M.; Arean, Patricia A.; Hunkeler, Enid; Tang, Lingqi; Katon, Wayne; Hitchcock, Polly; Steffens, David C.; Dickens, Jeanne; Unutzer, Jurgen

    2006-01-01

    Purpose: For depressed older primary care patients, this study aimed to examine (a) characteristics associated with depression treatment preferences; (b) predictors of receiving preferred treatment; and (c) whether receiving preferred treatment predicted satisfaction and depression outcomes. Design and Methods: Data are from 1,602 depressed older…

  14. Guidance and control of swarms of spacecraft

    Science.gov (United States)

    Morgan, Daniel James

    There has been considerable interest in formation flying spacecraft due to their potential to perform certain tasks at a cheaper cost than monolithic spacecraft. Formation flying enables the use of smaller, cheaper spacecraft that distribute the risk of the mission. Recently, the ideas of formation flying have been extended to spacecraft swarms made up of hundreds to thousands of 100-gram-class spacecraft known as femtosatellites. The large number of spacecraft and limited capabilities of each individual spacecraft present a significant challenge in guidance, navigation, and control. This dissertation deals with the guidance and control algorithms required to enable the flight of spacecraft swarms. The algorithms developed in this dissertation are focused on achieving two main goals: swarm keeping and swarm reconfiguration. The objectives of swarm keeping are to maintain bounded relative distances between spacecraft, prevent collisions between spacecraft, and minimize the propellant used by each spacecraft. Swarm reconfiguration requires the transfer of the swarm to a specific shape. Like with swarm keeping, minimizing the propellant used and preventing collisions are the main objectives. Additionally, the algorithms required for swarm keeping and swarm reconfiguration should be decentralized with respect to communication and computation so that they can be implemented on femtosats, which have limited hardware capabilities. The algorithms developed in this dissertation are concerned with swarms located in low Earth orbit. In these orbits, Earth oblateness and atmospheric drag have a significant effect on the relative motion of the swarm. The complicated dynamic environment of low Earth orbits further complicates the swarm-keeping and swarm-reconfiguration problems. To better develop and test these algorithms, a nonlinear, relative dynamic model with J2 and drag perturbations is developed. This model is used throughout this dissertation to validate the algorithms

  15. Embedded Thermal Control for Spacecraft Subsystems Miniaturization

    Science.gov (United States)

    Didion, Jeffrey R.

    2014-01-01

    Optimization of spacecraft size, weight and power (SWaP) resources is an explicit technical priority at Goddard Space Flight Center. Embedded Thermal Control Subsystems are a promising technology with many cross cutting NSAA, DoD and commercial applications: 1.) CubeSatSmallSat spacecraft architecture, 2.) high performance computing, 3.) On-board spacecraft electronics, 4.) Power electronics and RF arrays. The Embedded Thermal Control Subsystem technology development efforts focus on component, board and enclosure level devices that will ultimately include intelligent capabilities. The presentation will discuss electric, capillary and hybrid based hardware research and development efforts at Goddard Space Flight Center. The Embedded Thermal Control Subsystem development program consists of interrelated sub-initiatives, e.g., chip component level thermal control devices, self-sensing thermal management, advanced manufactured structures. This presentation includes technical status and progress on each of these investigations. Future sub-initiatives, technical milestones and program goals will be presented.

  16. Low power arcjet system spacecraft impacts

    Science.gov (United States)

    Pencil, Eric J.; Sarmiento, Charles J.; Lichtin, D. A.; Palchefsky, J. W.; Bogorad, A. L.

    1993-01-01

    Potential plume contamination of spacecraft surfaces was investigated by positioning spacecraft material samples relative to an arcjet thruster. Samples in the simulated solar array region were exposed to the cold gas arcjet plume for 40 hrs to address concerns about contamination by backstreaming diffusion pump oil. Except for one sample, no significant changes were measured in absorptance and emittance within experimental error. Concerns about surface property degradation due to electrostatic discharges led to the investigation of the discharge phenomenon of charged samples during arcjet ignition. Short duration exposure of charged samples demonstrated that potential differences are consistently and completely eliminated within the first second of exposure to a weakly ionized plume. The spark discharge mechanism was not the discharge phenomenon. The results suggest that the arcjet could act as a charge control device on spacecraft.

  17. Relativistic Spacecraft Propelled by Directed Energy

    Science.gov (United States)

    Kulkarni, Neeraj; Lubin, Philip; Zhang, Qicheng

    2018-04-01

    Achieving relativistic flight to enable extrasolar exploration is one of the dreams of humanity and the long-term goal of our NASA Starlight program. We derive a relativistic solution for the motion of a spacecraft propelled by radiation pressure from a directed energy (DE) system. Depending on the system parameters, low-mass spacecraft can achieve relativistic speeds, thus enabling interstellar exploration. The diffraction of the DE system plays an important role and limits the maximum speed of the spacecraft. We consider “photon recycling” as a possible method to achieving higher speeds. We also discuss recent claims that our previous work on this topic is incorrect and show that these claims arise from an improper treatment of causality.

  18. Numerical Analysis of Magnetic Sail Spacecraft

    International Nuclear Information System (INIS)

    Sasaki, Daisuke; Yamakawa, Hiroshi; Usui, Hideyuki; Funaki, Ikkoh; Kojima, Hirotsugu

    2008-01-01

    To capture the kinetic energy of the solar wind by creating a large magnetosphere around the spacecraft, magneto-plasma sail injects a plasma jet into a strong magnetic field produced by an electromagnet onboard the spacecraft. The aim of this paper is to investigate the effect of the IMF (interplanetary magnetic field) on the magnetosphere of magneto-plasma sail. First, using an axi-symmetric two-dimensional MHD code, we numerically confirm the magnetic field inflation, and the formation of a magnetosphere by the interaction between the solar wind and the magnetic field. The expansion of an artificial magnetosphere by the plasma injection is then simulated, and we show that the magnetosphere is formed by the interaction between the solar wind and the magnetic field expanded by the plasma jet from the spacecraft. This simulation indicates the size of the artificial magnetosphere becomes smaller when applying the IMF.

  19. Shutter mechanism for spacecraft spectrophotometer

    Science.gov (United States)

    Weilbach, A.

    1972-01-01

    A shutter mechanism is described for the backscatter ultraviolet spectrophotometer experiment on the Nimbus D satellite. The purpose of the experiment is to determine spatial distribution of atmospheric ozone from measurements of ultraviolet radiation backscattered by the earth's atmosphere. The system consists of two independent, rotary cylinder shutters, controlled by a dual star Geneva mechanism, and driven by a single stepper motor. A single driver controls a combination of two independently driven Geneva stars. Design considerations involved the use of low friction, nonmetallic materials.

  20. Autonomous Spacecraft Communication Interface for Load Planning

    Science.gov (United States)

    Dever, Timothy P.; May, Ryan D.; Morris, Paul H.

    2014-01-01

    Ground-based controllers can remain in continuous communication with spacecraft in low Earth orbit (LEO) with near-instantaneous communication speeds. This permits near real-time control of all of the core spacecraft systems by ground personnel. However, as NASA missions move beyond LEO, light-time communication delay issues, such as time lag and low bandwidth, will prohibit this type of operation. As missions become more distant, autonomous control of manned spacecraft will be required. The focus of this paper is the power subsystem. For present missions, controllers on the ground develop a complete schedule of power usage for all spacecraft components. This paper presents work currently underway at NASA to develop an architecture for an autonomous spacecraft, and focuses on the development of communication between the Mission Manager and the Autonomous Power Controller. These two systems must work together in order to plan future load use and respond to unanticipated plan deviations. Using a nominal spacecraft architecture and prototype versions of these two key components, a number of simulations are run under a variety of operational conditions, enabling development of content and format of the messages necessary to achieve the desired goals. The goals include negotiation of a load schedule that meets the global requirements (contained in the Mission Manager) and local power system requirements (contained in the Autonomous Power Controller), and communication of off-plan disturbances that arise while executing a negotiated plan. The message content is developed in two steps: first, a set of rapid-prototyping "paper" simulations are preformed; then the resultant optimized messages are codified for computer communication for use in automated testing.

  1. Enabling Advanced Automation in Spacecraft Operations with the Spacecraft Emergency Response System

    Science.gov (United States)

    Breed, Julie; Fox, Jeffrey A.; Powers, Edward I. (Technical Monitor)

    2001-01-01

    True autonomy is the Holy Grail of spacecraft mission operations. The goal of launching a satellite and letting it manage itself throughout its useful life is a worthy one. With true autonomy, the cost of mission operations would be reduced to a negligible amount. Under full autonomy, any problems (no matter the severity or type) that may arise with the spacecraft would be handled without any human intervention via some combination of smart sensors, on-board intelligence, and/or smart automated ground system. Until the day that complete autonomy is practical and affordable to deploy, incremental steps of deploying ever-increasing levels of automation (computerization of once manual tasks) on the ground and on the spacecraft are gradually decreasing the cost of mission operations. For example, NASA's Goddard Space Flight Center (NASA-GSFC) has been flying spacecraft with low cost operations for several years. NASA-GSFC's SMEX (Small Explorer) and MIDEX (Middle Explorer) missions have effectively deployed significant amounts of automation to enable the missions to fly predominately in 'light-out' mode. Under light-out operations the ground system is run without human intervention. Various tools perform many of the tasks previously performed by the human operators. One of the major issues in reducing human staff in favor of automation is the perceived increased in risk of losing data, or even losing a spacecraft, because of anomalous conditions that may occur when there is no one in the control center. When things go wrong, missions deploying advanced automation need to be sure that anomalous conditions are detected and that key personal are notified in a timely manner so that on-call team members can react to those conditions. To ensure the health and safety of its lights-out missions, NASA-GSFC's Advanced Automation and Autonomy branch (Code 588) developed the Spacecraft Emergency Response System (SERS). The SERS is a Web-based collaborative environment that enables

  2. Manned spacecraft electrical power systems

    Science.gov (United States)

    Simon, William E.; Nored, Donald L.

    1987-01-01

    A brief history of the development of electrical power systems from the earliest manned space flights illustrates a natural trend toward a growth of electrical power requirements and operational lifetimes with each succeeding space program. A review of the design philosophy and development experience associated with the Space Shuttle Orbiter electrical power system is presented, beginning with the state of technology at the conclusion of the Apollo Program. A discussion of prototype, verification, and qualification hardware is included, and several design improvements following the first Orbiter flight are described. The problems encountered, the scientific and engineering approaches used to meet the technological challenges, and the results obtained are stressed. Major technology barriers and their solutions are discussed, and a brief Orbiter flight experience summary of early Space Shuttle missions is included. A description of projected Space Station power requirements and candidate system concepts which could satisfy these anticipated needs is presented. Significant challenges different from Space Shuttle, innovative concepts and ideas, and station growth considerations are discussed. The Phase B Advanced Development hardware program is summarized and a status of Phase B preliminary tradeoff studies is presented.

  3. Testing programs for the Multimission Modular Spacecraft

    Science.gov (United States)

    Greenwell, T. J.

    1978-01-01

    The Multimission Modular Spacecraft (MMS) provides a standard spacecraft bus to a user for a variety of space missions ranging from near-earth to synchronous orbits. The present paper describes the philosophy behind the MMS module test program and discusses the implementation of the test program. It is concluded that the MMS module test program provides an effective and comprehensive customer buy-off at the subsystem contractor's plant, is an optimum approach for checkout of the subsystems prior to use for on-orbit servicing in the Shuttle Cargo Bay, and is a cost-effective technique for environmental testing.

  4. Spacecraft charging: incoming and outgoing electrons

    CERN Document Server

    Lai, Shu T.

    2013-04-22

    This paper presents an overview of the roles played by incoming and outgoing electrons in spacecraft surface and stresses the importance of surface conditions for spacecraft charging. The balance between the incoming electron current from the ambient plasma and the outgoing currents of secondary electrons, backscattered electrons, and photoelectrons from the surfaces determines the surface potential. Since surface conditions significantly affect the outgoing currents, the critical temperature and the surface potential are also significantly affected. As a corollary, high level differential charging of adjacent surfaces with very different surface conditions is a space hazard.

  5. Event-triggered attitude control of spacecraft

    Science.gov (United States)

    Wu, Baolin; Shen, Qiang; Cao, Xibin

    2018-02-01

    The problem of spacecraft attitude stabilization control system with limited communication and external disturbances is investigated based on an event-triggered control scheme. In the proposed scheme, information of attitude and control torque only need to be transmitted at some discrete triggered times when a defined measurement error exceeds a state-dependent threshold. The proposed control scheme not only guarantees that spacecraft attitude control errors converge toward a small invariant set containing the origin, but also ensures that there is no accumulation of triggering instants. The performance of the proposed control scheme is demonstrated through numerical simulation.

  6. Preference learning for cognitive modeling: a case study on entertainment preferences

    DEFF Research Database (Denmark)

    Yannakakis, Georgios; Maragoudakis, Manolis; Hallam, John

    2009-01-01

    Learning from preferences, which provide means for expressing a subject's desires, constitutes an important topic in machine learning research. This paper presents a comparative study of four alternative instance preference learning algorithms (both linear and nonlinear). The case study...... investigated is to learn to predict the expressed entertainment preferences of children when playing physical games built on their personalized playing features (entertainment modeling). Two of the approaches are derived from the literature--the large-margin algorithm (LMA) and preference learning...... with Gaussian processes--while the remaining two are custom-designed approaches for the problem under investigation: meta-LMA and neuroevolution. Preference learning techniques are combined with feature set selection methods permitting the construction of effective preference models, given suitable individual...

  7. Development of Large-Scale Spacecraft Fire Safety Experiments

    DEFF Research Database (Denmark)

    Ruff, Gary A.; Urban, David L.; Fernandez-Pello, A. Carlos

    2013-01-01

    exploration missions outside of low-earth orbit and accordingly, more complex in terms of operations, logistics, and safety. This will increase the challenge of ensuring a fire-safe environment for the crew throughout the mission. Based on our fundamental uncertainty of the behavior of fires in low...... of the spacecraft fire safety risk. The activity of this project is supported by an international topical team of fire experts from other space agencies who conduct research that is integrated into the overall experiment design. The large-scale space flight experiment will be conducted in an Orbital Sciences...

  8. The TESIS experiment on the CORONAS-PHOTON spacecraft

    Science.gov (United States)

    Kuzin, S. V.; Zhitnik, I. A.; Shestov, S. V.; Bogachev, S. A.; Bugaenko, O. I.; Ignat'ev, A. P.; Pertsov, A. A.; Ulyanov, A. S.; Reva, A. A.; Slemzin, V. A.; Sukhodrev, N. K.; Ivanov, Yu. S.; Goncharov, L. A.; Mitrofanov, A. V.; Popov, S. G.; Shergina, T. A.; Solov'ev, V. A.; Oparin, S. N.; Zykov, A. M.

    2011-04-01

    On February 26, 2009, the first data was obtained in the TESIS experiment on the research of the solar corona using imaging spectroscopy. The TESIS is a part of the scientific equipment of the CORONAS-PHO-TON spacecraft and is designed for imaging the solar corona in soft X-ray and extreme ultraviolet regions of the spectrum with high spatial, spectral, and temporal resolutions at altitudes from the transition region to three solar radii. The article describes the main characteristics of the instrumentation, management features, and operation modes.

  9. Investigation of fast initialization of spacecraft bubble memory systems

    Science.gov (United States)

    Looney, K. T.; Nichols, C. D.; Hayes, P. J.

    1984-01-01

    Bubble domain technology offers significant improvement in reliability and functionality for spacecraft onboard memory applications. In considering potential memory systems organizations, minimization of power in high capacity bubble memory systems necessitates the activation of only the desired portions of the memory. In power strobing arbitrary memory segments, a capability of fast turn on is required. Bubble device architectures, which provide redundant loop coding in the bubble devices, limit the initialization speed. Alternate initialization techniques are investigated to overcome this design limitation. An initialization technique using a small amount of external storage is demonstrated.

  10. Theoretical analysis of infrared radiation shields of spacecraft

    Science.gov (United States)

    Shealy, D. L.

    1984-01-01

    For a system of N diffuse, gray body radiation shields which view only adjacent surfaces and space, the net radiation method for enclosures has been used to formulate a system of linear, nonhomogeneous equations in terms of the temperatures to the fourth power of each surface in the coupled system of enclosures. The coefficients of the unknown temperatures in the system of equations are expressed in terms of configuration factors between adjacent surfaces and the emissivities. As an application, a system of four conical radiation shields for a spin stabilized STARPROBE spacecraft has been designed and analyzed with respect to variations of the cone half angles, the intershield spacings, and emissivities.

  11. FMT (Flight Software Memory Tracker) For Cassini Spacecraft-Software Engineering Using JAVA

    Science.gov (United States)

    Kan, Edwin P.; Uffelman, Hal; Wax, Allan H.

    1997-01-01

    The software engineering design of the Flight Software Memory Tracker (FMT) Tool is discussed in this paper. FMT is a ground analysis software set, consisting of utilities and procedures, designed to track the flight software, i.e., images of memory load and updatable parameters of the computers on-board Cassini spacecraft. FMT is implemented in Java.

  12. Revealed smooth nontransitive preferences

    DEFF Research Database (Denmark)

    Keiding, Hans; Tvede, Mich

    2013-01-01

    In the present paper, we are concerned with the behavioural consequences of consumers having nontransitive preference relations. Data sets consist of finitely many observations of price vectors and consumption bundles. A preference relation rationalizes a data set provided that for every observed...... consumption bundle, all strictly preferred bundles are more expensive than the observed bundle. Our main result is that data sets can be rationalized by a smooth nontransitive preference relation if and only if prices can normalized such that the law of demand is satisfied. Market data sets consist of finitely...... many observations of price vectors, lists of individual incomes and aggregate demands. We apply our main result to characterize market data sets consistent with equilibrium behaviour of pure-exchange economies with smooth nontransitive consumers....

  13. Consumers’ preferences for bread

    DEFF Research Database (Denmark)

    Edenbrandt, Anna Kristina; Gamborg, Christian; Thorsen, Bo Jellesmark

    2017-01-01

    Consumers are apprehensive about transgenic technologies, so cisgenics, which limit gene transfers to sexually compatible organisms, have been suggested to address consumer concerns. We study consumer preferences for rye bread alternatives based on transgenic or cisgenic rye, grown conventionally...

  14. Customer Preference-Based Information Retrieval to Build Module Concepts

    Directory of Open Access Journals (Sweden)

    Dongxing Cao

    2013-01-01

    Full Text Available Preference is viewed as an outer feeling of a product, also as a reflection of human's inner thought. It dominates the designers' decisions and affects our purchase intention. In the paper, a model of preference elicitation from customers is proposed to build module concepts. Firstly, the attributes of customer preference are classified in a hierarchy and make the surveys to build customer preference concepts. Secondly, the documents or catalogs of design requirements, perhaps containing some textual description and geometric data, are normalized by using semantic expressions. Some semantic rules are developed to describe low-level features of customer preference to construct a knowledge base of customer preference. Thirdly, designers' needs are used to map customer preference for generating module concepts. Finally, an empirical study of the stapler is surveyed to illustrate the validity of module concept generation.

  15. Teachers' preferences towards textbook

    Directory of Open Access Journals (Sweden)

    Stanojević Darko D.

    2016-01-01

    Full Text Available In this paper, using the method named Conjoint analysis, and with the goal of determining teacher's preferences in the process of textbook selection, and also defining the prototype of quality textbook which will could be used in the classroom. With consideration of criteria defined in the previous researches on this topic, an continuing the work on those results, we will create clear hypothetical prototype of the textbook which will satisfy the teacher's preference.

  16. Topology Control Algorithms for Spacecraft Formation Flying Networks Under Connectivity and Time-Delay Constraints, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — SSCI is proposing to develop, test and deliver a set of topology control algorithms and software for a formation flying spacecraft that can be used to design and...

  17. Topology Control Algorithms for Spacecraft Formation Flying Networks Under Connectivity and Time-Delay Constraints, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — SSCI is proposing to develop a set of topology control algorithms for a formation flying spacecraft that can be used to design and evaluate candidate formation...

  18. Personnel preferences in personnel planning and scheduling

    OpenAIRE

    van der Veen, Egbert

    2013-01-01

    Summary The personnel of an organization often has two conflicting goals. Individual employees like to have a good work-life balance, by having personal preferences taken into account, whereas there is also the common goal to work efficiently. By applying techniques and methods from Operations Research, a subfield of applied mathematics, we show that operational efficiency can be achieved while taking personnel preferences into account. In the design of optimization methods, we explicitly con...

  19. Topology Optimization of Spacecraft Transfer Compartment

    Directory of Open Access Journals (Sweden)

    A. A. Borovikov

    2016-01-01

    Full Text Available IntroductionThe subject of this research is topology optimization of the adapter of a spacecraft transfer compartment. The finite element topology optimization [1] is widely used for simple structure elements [6, 7]. It is argued that using this method in conjunction with additive technology (3D - printing it is possible to create construction designs with the best weight characteristics. However, the paper shows that when applying this method to a complex construction design the optimization results are highly sensitive to optimization algorithm parameters. The goal of this research is to study parameters of the topology optimization algorithm and the influence of their variations on results.1.      Problem formulation   A commercial software Altair HyperWorks/OptiStruct (student’s license performed numerical calculations. The paper presents a detailed description of the finite element model.The main features of the proposed model are as follows:-          Simplicity with non-complicated geometry;-          Building a finite element model in terms of computing time minimization;-          Using the lumped mass elements to simulate the impacts of the conjugates on the adapter;-          A limit of material strength, decreased by an order of magnitude, to eliminate stress concentrators;-          The gravitational load applied corresponds to the loads for the Angara-A5 launcher [8]. 2.      Method of solutionA brief description of the SIMP-method realized in the Altair HyperWorks/OptiStruct software is given.3.      ResultsPerformed numerical calculations, and shown the influence of variations of algorithm parameters (DISCRETE, MATINIT, MINDIM, MAXDIM on construction design as well as the parameters SINGLE and SPLIT used to reveal restrictions on manufacturing.Shown that, depending on variations of parameters, an adapter construction strives to «truss» or «shell» type. Described

  20. Software for Engineering Simulations of a Spacecraft

    Science.gov (United States)

    Shireman, Kirk; McSwain, Gene; McCormick, Bernell; Fardelos, Panayiotis

    2005-01-01

    Spacecraft Engineering Simulation II (SES II) is a C-language computer program for simulating diverse aspects of operation of a spacecraft characterized by either three or six degrees of freedom. A functional model in SES can include a trajectory flight plan; a submodel of a flight computer running navigational and flight-control software; and submodels of the environment, the dynamics of the spacecraft, and sensor inputs and outputs. SES II features a modular, object-oriented programming style. SES II supports event-based simulations, which, in turn, create an easily adaptable simulation environment in which many different types of trajectories can be simulated by use of the same software. The simulation output consists largely of flight data. SES II can be used to perform optimization and Monte Carlo dispersion simulations. It can also be used to perform simulations for multiple spacecraft. In addition to its generic simulation capabilities, SES offers special capabilities for space-shuttle simulations: for this purpose, it incorporates submodels of the space-shuttle dynamics and a C-language version of the guidance, navigation, and control components of the space-shuttle flight software.

  1. Spacecraft 3D Augmented Reality Mobile App

    Science.gov (United States)

    Hussey, Kevin J.; Doronila, Paul R.; Kumanchik, Brian E.; Chan, Evan G.; Ellison, Douglas J.; Boeck, Andrea; Moore, Justin M.

    2013-01-01

    The Spacecraft 3D application allows users to learn about and interact with iconic NASA missions in a new and immersive way using common mobile devices. Using Augmented Reality (AR) techniques to project 3D renditions of the mission spacecraft into real-world surroundings, users can interact with and learn about Curiosity, GRAIL, Cassini, and Voyager. Additional updates on future missions, animations, and information will be ongoing. Using a printed AR Target and camera on a mobile device, users can get up close with these robotic explorers, see how some move, and learn about these engineering feats, which are used to expand knowledge and understanding about space. The software receives input from the mobile device's camera to recognize the presence of an AR marker in the camera's field of view. It then displays a 3D rendition of the selected spacecraft in the user's physical surroundings, on the mobile device's screen, while it tracks the device's movement in relation to the physical position of the spacecraft's 3D image on the AR marker.

  2. Special Semaphore Scheme for UHF Spacecraft Communications

    Science.gov (United States)

    Butman, Stanley; Satorius, Edgar; Ilott, Peter

    2006-01-01

    A semaphore scheme has been devised to satisfy a requirement to enable ultrahigh- frequency (UHF) radio communication between a spacecraft descending from orbit to a landing on Mars and a spacecraft, in orbit about Mars, that relays communications between Earth and the lander spacecraft. There are also two subsidiary requirements: (1) to use UHF transceivers, built and qualified for operation aboard the spacecraft that operate with residual-carrier binary phase-shift-keying (BPSK) modulation at a selectable data rate of 8, 32, 128, or 256 kb/s; and (2) to enable low-rate signaling even when received signals become so weak as to prevent communication at the minimum BPSK rate of 8 kHz. The scheme involves exploitation of Manchester encoding, which is used in conjunction with residual-carrier modulation to aid the carrier-tracking loop. By choosing various sequences of 1s, 0s, or 1s alternating with 0s to be fed to the residual-carrier modulator, one would cause the modulator to generate sidebands at a fundamental frequency of 4 or 8 kHz and harmonics thereof. These sidebands would constitute the desired semaphores. In reception, the semaphores would be detected by a software demodulator.

  3. Accelerated life testing of spacecraft subsystems

    Science.gov (United States)

    Wiksten, D.; Swanson, J.

    1972-01-01

    The rationale and requirements for conducting accelerated life tests on electronic subsystems of spacecraft are presented. A method for applying data on the reliability and temperature sensitivity of the parts contained in a sybsystem to the selection of accelerated life test parameters is described. Additional considerations affecting the formulation of test requirements are identified, and practical limitations of accelerated aging are described.

  4. Small Spacecraft Technology Initiative Education Program

    Science.gov (United States)

    1995-01-01

    A NASA engineer with the Commercial Remote Sensing Program (CRSP) at Stennis Space Center works with students from W.P. Daniels High School in New Albany, Miss., through NASA's Small Spacecraft Technology Initiative Program. CRSP is teaching students to use remote sensing to locate a potential site for a water reservoir to offset a predicted water shortage in the community's future.

  5. The relationship between personality types and reward preferences

    Directory of Open Access Journals (Sweden)

    R. Nienaber

    2011-12-01

    Full Text Available Orientation: Research has shown that total rewards models structured according to individual preferences, positively influence efforts to attract, retain and motivate key employees. Yet, this is seldom done. Structuring total rewards models according to the preferences of employee segments is a viable alternative to accommodate individual preferences. Research purpose: The primary aim of the study was to determine the relationship between personality types and reward preferences. The secondary aim was to determine the reward preferences for different demographic groups. Motivation for the study: An enhanced understanding of reward preferences for different employee segments will enable employers to offer more competitive reward options to their employees. This may, in turn, have a positive impact on retention. Research design, approach and method: Two measuring instruments, the MBTI® Form GRV and the Rewards Preferences Questionnaire, were distributed electronically to 5 000 potential respondents. The results from 589 sets of questionnaires were used in the data analyses. Primary and secondary factor analyses were done on the items in the Rewards Preferences Questionnaire. Main findings/results: The study confirmed that individuals with certain personality types and personality preferences, have different preferences for certain reward categories. There was a stronger relationship between reward preferences and personality preferences than for reward preferences and personality types. Preferences for reward categories by different demographic groups were confirmed. The significant difference in reward preferences between Black and White respondents in particular was noteworthy, with Black respondents indicating significantly higher mean scores for all reward categories than White respondents. Finally, a total rewards framework influenced by the most prominent preferences for reward categories, was designed. Practical/Managerial implications

  6. Age Preferences for Professional Helpers.

    Science.gov (United States)

    Furchtgott, Ernest; Busemeyer, Jerome R.

    1981-01-01

    For all occupations except clergyman, a relationship between the age of the respondent and preferred age of the professional existed. Older individuals preferred older service providers with one exception, their physician. Highly educated respondents preferred younger physicians. (Author)

  7. Preference Handling for Artificial Intelligence

    OpenAIRE

    Goldsmith, Judy; University of Kentucky; Junker, Ulrich; ILOG

    2009-01-01

    This article explains the benefits of preferences for AI systems and draws a picture of current AI research on preference handling. It thus provides an introduction to the topics covered by this special issue on preference handling.

  8. Spacecraft Internal Acoustic Environment Modeling

    Science.gov (United States)

    Chu, Shao-Sheng R.; Allen Christopher S.

    2010-01-01

    Acoustic modeling can be used to identify key noise sources, determine/analyze sub-allocated requirements, keep track of the accumulation of minor noise sources, and to predict vehicle noise levels at various stages in vehicle development, first with estimates of noise sources, later with experimental data. This paper describes the implementation of acoustic modeling for design purposes by incrementally increasing model fidelity and validating the accuracy of the model while predicting the noise of sources under various conditions. During FY 07, a simple-geometry Statistical Energy Analysis (SEA) model was developed and validated using a physical mockup and acoustic measurements. A process for modeling the effects of absorptive wall treatments and the resulting reverberation environment were developed. During FY 08, a model with more complex and representative geometry of the Orion Crew Module (CM) interior was built, and noise predictions based on input noise sources were made. A corresponding physical mockup was also built. Measurements were made inside this mockup, and comparisons were made with the model and showed excellent agreement. During FY 09, the fidelity of the mockup and corresponding model were increased incrementally by including a simple ventilation system. The airborne noise contribution of the fans was measured using a sound intensity technique, since the sound power levels were not known beforehand. This is opposed to earlier studies where Reference Sound Sources (RSS) with known sound power level were used. Comparisons of the modeling result with the measurements in the mockup showed excellent results. During FY 10, the fidelity of the mockup and the model were further increased by including an ECLSS (Environmental Control and Life Support System) wall, associated closeout panels, and the gap between ECLSS wall and mockup wall. The effect of sealing the gap and adding sound absorptive treatment to ECLSS wall were also modeled and validated.

  9. Micro-Inspector Spacecraft for Space Exploration Missions

    Science.gov (United States)

    Mueller, Juergen; Alkalai, Leon; Lewis, Carol

    2005-01-01

    NASA is seeking to embark on a new set of human and robotic exploration missions back to the Moon, to Mars, and destinations beyond. Key strategic technical challenges will need to be addressed to realize this new vision for space exploration, including improvements in safety and reliability to improve robustness of space operations. Under sponsorship by NASA's Exploration Systems Mission, the Jet Propulsion Laboratory (JPL), together with its partners in government (NASA Johnson Space Center) and industry (Boeing, Vacco Industries, Ashwin-Ushas Inc.) is developing an ultra-low mass (missions. The micro-inspector will provide remote vehicle inspections to ensure safety and reliability, or to provide monitoring of in-space assembly. The micro-inspector spacecraft represents an inherently modular system addition that can improve safety and support multiple host vehicles in multiple applications. On human missions, it may help extend the reach of human explorers, decreasing human EVA time to reduce mission cost and risk. The micro-inspector development is the continuation of an effort begun under NASA's Office of Aerospace Technology Enabling Concepts and Technology (ECT) program. The micro-inspector uses miniaturized celestial sensors; relies on a combination of solar power and batteries (allowing for unlimited operation in the sun and up to 4 hours in the shade); utilizes a low-pressure, low-leakage liquid butane propellant system for added safety; and includes multi-functional structure for high system-level integration and miniaturization. Versions of this system to be designed and developed under the H&RT program will include additional capabilities for on-board, vision-based navigation, spacecraft inspection, and collision avoidance, and will be demonstrated in a ground-based, space-related environment. These features make the micro-inspector design unique in its ability to serve crewed as well as robotic spacecraft, well beyond Earth-orbit and into arenas such

  10. Internal Acoustics of the ISS and Other Spacecraft

    Science.gov (United States)

    Allen, Christopher S.

    2017-01-01

    It is important to control the acoustic environment inside spacecraft and space habitats to protect for astronaut communications, alarm audibility, and habitability, and to reduce astronauts' risk for sleep disturbance, and hear-ing loss. But this is not an easy task, given the various design trade-offs, and it has been difficult, historically, to achieve. Over time it has been found that successful control of spacecraft acoustic levels is achieved by levying firm requirements at the system-level, using a systems engineering approach for design and development, and then validating these requirements with acoustic testing. In the systems engineering method, the system-level requirements must be flowed down to sub-systems and component noise sources, using acoustic analysis and acoustic modelling to develop allocated requirements for the sub-systems and components. Noise controls must also be developed, tested, and implemented so the sub-systems and components can achieve their allocated limits. It is also important to have management support for acoustics efforts to maintain their priority against the various trade-offs, including mass, volume, power, cost, and schedule. In this extended abstract and companion presentation, the requirements, approach, and results for controlling acoustic levels in most US spacecraft since Apollo will be briefly discussed. The approach for controlling acoustic levels in the future US space vehicle, Orion Multipurpose Crew Vehicle (MPCV), will also be briefly discussed. These discussions will be limited to the control of continuous noise inside the space vehicles. Other types of noise, such as launch, landing, and abort noise, intermittent noise, Extra-Vehicular Activity (EVA) noise, emergency operations/off-nominal noise, noise exposure, and impulse noise are important, but will not be discussed because of time limitations.

  11. Spacecraft electrical power subsystem: Failure behavior, reliability, and multi-state failure analyses

    International Nuclear Information System (INIS)

    Kim, So Young; Castet, Jean-Francois; Saleh, Joseph H.

    2012-01-01

    This article investigates the degradation and failure behavior of spacecraft electrical power subsystem (EPS) on orbit. First, this work provides updated statistical reliability and multi-state failure analyses of spacecraft EPS and its different constituents, namely the batteries, the power distribution, and the solar arrays. The EPS is shown to suffer from infant mortality and to be a major driver of spacecraft unreliability. Over 25% of all spacecraft failures are the result of EPS failures. As a result, satellite manufacturers may wish to pursue targeted improvement to this subsystem, either through better testing or burn-in procedures, better design or parts selection, or additional redundancy. Second, this work investigates potential differences in the EPS degradation and failure behavior for spacecraft in low earth orbits (LEO) and geosynchronous orbits (GEO). This analysis was motivated by the recognition that the power/load cycles and the space environment are significantly different in LEO and GEO, and as such, they may result in different failure behavior for the EPS in these two types of orbits. The results indicate, and quantify the extent to which, the EPS fails differently in LEO and GEO, both in terms of frequency and severity of failure events. A casual summary of the findings can be stated as follows: the EPS fails less frequently but harder (with fatal consequences to the spacecraft) in LEO than in GEO.

  12. SHARP: A multi-mission artificial intelligence system for spacecraft telemetry monitoring and diagnosis

    Science.gov (United States)

    Lawson, Denise L.; James, Mark L.

    1989-01-01

    The Spacecraft Health Automated Reasoning Prototype (SHARP) is a system designed to demonstrate automated health and status analysis for multi-mission spacecraft and ground data systems operations. Telecommunications link analysis of the Voyager 2 spacecraft is the initial focus for the SHARP system demonstration which will occur during Voyager's encounter with the planet Neptune in August, 1989, in parallel with real time Voyager operations. The SHARP system combines conventional computer science methodologies with artificial intelligence techniques to produce an effective method for detecting and analyzing potential spacecraft and ground systems problems. The system performs real time analysis of spacecraft and other related telemetry, and is also capable of examining data in historical context. A brief introduction is given to the spacecraft and ground systems monitoring process at the Jet Propulsion Laboratory. The current method of operation for monitoring the Voyager Telecommunications subsystem is described, and the difficulties associated with the existing technology are highlighted. The approach taken in the SHARP system to overcome the current limitations is also described, as well as both the conventional and artificial intelligence solutions developed in SHARP.

  13. SHARP: A multi-mission AI system for spacecraft telemetry monitoring and diagnosis

    Science.gov (United States)

    Lawson, Denise L.; James, Mark L.

    1989-01-01

    The Spacecraft Health Automated Reasoning Prototype (SHARP) is a system designed to demonstrate automated health and status analysis for multi-mission spacecraft and ground data systems operations. Telecommunications link analysis of the Voyager II spacecraft is the initial focus for the SHARP system demonstration which will occur during Voyager's encounter with the planet Neptune in August, 1989, in parallel with real-time Voyager operations. The SHARP system combines conventional computer science methodologies with artificial intelligence techniques to produce an effective method for detecting and analyzing potential spacecraft and ground systems problems. The system performs real-time analysis of spacecraft and other related telemetry, and is also capable of examining data in historical context. A brief introduction is given to the spacecraft and ground systems monitoring process at the Jet Propulsion Laboratory. The current method of operation for monitoring the Voyager Telecommunications subsystem is described, and the difficulties associated with the existing technology are highlighted. The approach taken in the SHARP system to overcome the current limitations is also described, as well as both the conventional and artificial intelligence solutions developed in SHARP.

  14. A Study of Learning Curve Impact on Three Identical Small Spacecraft

    Science.gov (United States)

    Chen, Guangming; McLennan, Douglas D.

    2003-01-01

    With an eye to the future strategic needs of NASA, the New Millennium Program is funding the Space Technology 5 (ST-5) project to address the future needs in the area of small satellites in constellation missions. The ST-5 project, being developed at Goddard Space Flight Center, involves the development and simultaneous launch of three small, 20-kilogram-class spacecraft. ST-5 is only a test drive and future NASA science missions may call for fleets of spacecraft containing tens of smart and capable satellites in an intelligent constellation. The objective of ST-5 project is to develop three such pioneering small spacecraft for flight validation of several critical new technologies. The ST-5 project team at Goddard Space Flight Center has completed the spacecraft design, is now building and testing the three flight units. The launch readiness date (LRD) is in December 2005. A critical part of ST-5 mission is to prove that it is possible to build these small but capable spacecraft with recurring cost low enough to make future NASA s multi- spacecraft constellation missions viable from a cost standpoint.

  15. Attitude dynamics and control of spacecraft with a partially filled liquid tank and flexible panels

    Science.gov (United States)

    Liu, Feng; Yue, Baozeng; Zhao, Liangyu

    2018-02-01

    A liquid-filled flexible spacecraft is essentially a time-variant fully-coupled system, whose dynamics characteristics are closely associated with its motion features. This paper focuses on the mathematical modelling and attitude control of the spacecraft coupled with fuel sloshing dynamics and flexible solar panels vibration. The slosh motion is represented by a spherical pendulum, whose motion description method is improved by using split variable operation. Benefiting from this improvement, the nonlinear lateral sloshing and the rotary sloshing as well as the rigid motion of a liquid respect to the spacecraft can be approximately described. The assumed modes discretization method has been adopted to approximate the elastic displacements of the attached panels, and the coupled dynamics is derived by using the Lagrangian formulation. A variable substitution method is proposed to obtain the apparently-uncoupled mathematical model of the rigid-flexible-liquid spacecraft. After linearization, this model can be directly used for designing Lyapunov output-feedback attitude controller (OFAC). With only torque actuators, and attitude and rate sensors installed, this kind of attitude controller, as simulation results show, is capable of not only bringing the spacecraft to the desired orientation, but also suppressing the effect of flex and slosh on the attitude motion of the spacecraft.

  16. An Analysis of 20 Years of Space Weathering Effects on the Boeing 376 Spacecraft

    Science.gov (United States)

    Frith, James; Anz-Meador, Phillip; Cowardin, Heather; Buckalew, Brent; Lederer, Susan

    2015-01-01

    The Boeing HS-376 spin stabilized spacecraft was a popular design that was launched continuously into geosynchronous orbit starting in 1980, with the last launch occurring in 2003. Over 50 of the HS-376 buses were produced to fulfill a variety of different communication missions for countries all over the world. The design of the bus is easily approximated as a telescoping cylinder that is covered with solar cells and an Earth-facing antenna that is despun at the top of the cylinder. The similarity in design and the number of spacecraft launched over a long period of time make the HS-376 a prime target for studying the effects of solar weathering on solar panels as a function of time. A selection of primarily non-operational HS-376 spacecraft launched over a 20-year time period were observed using the United Kingdom Infrared Telescope on Mauna Kea and multi-band, near-infrared photometry produced. Each spacecraft was observed for an entire night cycling through ZYJHK filters and time-varying colors produced to compare near-infrared color as a function of launch date. The resulting analysis shown here may help in the future to set launch date constraints on the parent object of unidentified debris objects or other unknown spacecraft.

  17. The use of twin-screen-based WIMPS in spacecraft control

    Science.gov (United States)

    Klim, R. D.

    1990-10-01

    The ergonomic problems of designing a sophisticated Windows Icons Mouse Pop-up (WIMP) based twin screen workstation are outlined. These same problems will be encountered by future spacecraft controllers. The design of a modern, advanced workstation for use on a distributed multicontrol center in a multisatellite control system is outlined. The system uses access control mechanisms to ensure that only authorized personnel can undertake certain operations on the workstation. Rules governing the use of windowing features, screen attributes, icons, keyboard and mouse in spacecraft control are discussed.

  18. On the spacecraft attitude stabilization in the orbital frame

    Directory of Open Access Journals (Sweden)

    Antipov Kirill A.

    2012-01-01

    Full Text Available The paper deals with spacecraft in the circular near-Earth orbit. The spacecraft interacts with geomagnetic field by the moments of Lorentz and magnetic forces. The octupole approximation of the Earth’s magnetic field is accepted. The spacecraft electromagnetic parameters, namely the electrostatic charge moment of the first order and the eigen magnetic moment are the controlled quasiperiodic functions. The control algorithms for the spacecraft electromagnetic parameters, which allows to stabilize the spacecraft attitude position in the orbital frame are obtained. The stability of the spacecraft stabilized orientation is proved both analytically and by PC computations.

  19. Protecting Spacecraft Fragments from Exposure to Small Debris

    Directory of Open Access Journals (Sweden)

    V. V. Zelentsov

    2015-01-01

    Full Text Available Since the launch of the first artificial Earth satellite a large amount of space debris has been accumulated in near-earth space. This debris comprises the exhausted spacecrafts, final stages of rocket-carriers and boosters, technological space junk, consisting of the structure elements, which are separated when deploying the solar arrays, antennas etc., as well as when undocking a booster and a spacecraft. All the debris is divided into observable one of over 100 mm in size and unobservable debris. In case of possible collision with the observed debris an avoidance manoeuvre is provided. The situation with unobservable debris is worse, its dimensions ranging from 100 mm to several microns. This debris is formed as a result of explosions of dead space objects and at collisions of destroyed spacecraft fragments against each other. This debris moves along arbitrary trajectories at different speeds.At collision of a spacecraft with fragments of small-size space debris, various consequences are possible: the device can immediately fail, suffer damages, which will have effect later and damages, which break no bones to the aircraft. Anyway, the spacecraft collision with small-size debris particles is undesirable. The protective shields are used to protect the aircraft from damage. Development of shield construction is complicated because the high cost of launch makes it impossible to conduct field tests of shields in space. All the work is carried out in the laboratory, with particles having co-impact speeds up to 10 km/s (possible speeds are up to 20 km/s and spherically shaped particles of 0.8 ... 3 mm in diameter.Various materials are used to manufacture shields. These are aluminum sheet, sandwich panels, metal mesh, metal foam, and woven materials (ballistic fabric. The paper considers single-layer (from sheet metal sandwich materials and multilayer shield designs. As experimental studies show, a single-layer shield protects colliding at speeds

  20. NASA Spacecraft Fault Management Workshop Results

    Science.gov (United States)

    Newhouse, Marilyn; McDougal, John; Barley, Bryan; Fesq, Lorraine; Stephens, Karen

    2010-01-01

    Fault Management is a critical aspect of deep-space missions. For the purposes of this paper, fault management is defined as the ability of a system to detect, isolate, and mitigate events that impact, or have the potential to impact, nominal mission operations. The fault management capabilities are commonly distributed across flight and ground subsystems, impacting hardware, software, and mission operations designs. The National Aeronautics and Space Administration (NASA) Discovery & New Frontiers (D&NF) Program Office at Marshall Space Flight Center (MSFC) recently studied cost overruns and schedule delays for 5 missions. The goal was to identify the underlying causes for the overruns and delays, and to develop practical mitigations to assist the D&NF projects in identifying potential risks and controlling the associated impacts to proposed mission costs and schedules. The study found that 4 out of the 5 missions studied had significant overruns due to underestimating the complexity and support requirements for fault management. As a result of this and other recent experiences, the NASA Science Mission Directorate (SMD) Planetary Science Division (PSD) commissioned a workshop to bring together invited participants across government, industry, academia to assess the state of the art in fault management practice and research, identify current and potential issues, and make recommendations for addressing these issues. The workshop was held in New Orleans in April of 2008. The workshop concluded that fault management is not being limited by technology, but rather by a lack of emphasis and discipline in both the engineering and programmatic dimensions. Some of the areas cited in the findings include different, conflicting, and changing institutional goals and risk postures; unclear ownership of end-to-end fault management engineering; inadequate understanding of the impact of mission-level requirements on fault management complexity; and practices, processes, and

  1. Measuring higher order ambiguity preferences.

    Science.gov (United States)

    Baillon, Aurélien; Schlesinger, Harris; van de Kuilen, Gijs

    2018-01-01

    We report the results from an experiment designed to measure attitudes towards ambiguity beyond ambiguity aversion. In particular, we implement recently-proposed model-free preference conditions of ambiguity prudence and ambiguity temperance. Ambiguity prudence has been shown to play an important role in precautionary behavior and the mere presence of ambiguity averse agents in markets. We observe that the majority of individuals' decisions are consistent with ambiguity aversion, ambiguity prudence and ambiguity temperance. This finding confirms the prediction of many popular (specifications of) ambiguity models and has important implications for models of prevention behavior.

  2. Materials Characterization at Utah State University: Facilities and Knowledge-base of Electronic Properties of Materials Applicable to Spacecraft Charging

    Science.gov (United States)

    Dennison, J. R.; Thomson, C. D.; Kite, J.; Zavyalov, V.; Corbridge, Jodie

    2004-01-01

    In an effort to improve the reliability and versatility of spacecraft charging models designed to assist spacecraft designers in accommodating and mitigating the harmful effects of charging on spacecraft, the NASA Space Environments and Effects (SEE) Program has funded development of facilities at Utah State University for the measurement of the electronic properties of both conducting and insulating spacecraft materials. We present here an overview of our instrumentation and capabilities, which are particularly well suited to study electron emission as related to spacecraft charging. These measurements include electron-induced secondary and backscattered yields, spectra, and angular resolved measurements as a function of incident energy, species and angle, plus investigations of ion-induced electron yields, photoelectron yields, sample charging and dielectric breakdown. Extensive surface science characterization capabilities are also available to fully characterize the samples in situ. Our measurements for a wide array of conducting and insulating spacecraft materials have been incorporated into the SEE Charge Collector Knowledge-base as a Database of Electronic Properties of Materials Applicable to Spacecraft Charging. This Database provides an extensive compilation of electronic properties, together with parameterization of these properties in a format that can be easily used with existing spacecraft charging engineering tools and with next generation plasma, charging, and radiation models. Tabulated properties in the Database include: electron-induced secondary electron yield, backscattered yield and emitted electron spectra; He, Ar and Xe ion-induced electron yields and emitted electron spectra; photoyield and solar emittance spectra; and materials characterization including reflectivity, dielectric constant, resistivity, arcing, optical microscopy images, scanning electron micrographs, scanning tunneling microscopy images, and Auger electron spectra. Further

  3. Measuring children's food preferences

    DEFF Research Database (Denmark)

    Olsen, Annemarie; Kildegaard, Heidi; Gabrielsen, Gorm

    2012-01-01

    The aim of this study is to investigate if children’s food preferences can be reliable measured by using pictures of foods presented on a computer screen in a conjoint layout.We investigate reproducibility (test–retest) and infer validity by comparison with traditional hedonic evaluations...... juices (tangible products), chosen to span the preference spectrum, were hedonically evaluated for appearance and taste. Finally, an actual product choice was performed by having the children choose between two buns and two juices.Results showed that the computer evaluationswith pictures of foods...... provided reproducible information about the children’s visual food preferences, which were in concordance with both hedonic measures and products choices, and can thus be considered valid....

  4. On-orbit assembly of a team of flexible spacecraft using potential field based method

    Science.gov (United States)

    Chen, Ti; Wen, Hao; Hu, Haiyan; Jin, Dongping

    2017-04-01

    In this paper, a novel control strategy is developed based on artificial potential field for the on-orbit autonomous assembly of four flexible spacecraft without inter-member collision. Each flexible spacecraft is simplified as a hub-beam model with truncated beam modes in the floating frame of reference and the communication graph among the four spacecraft is assumed to be a ring topology. The four spacecraft are driven to a pre-assembly configuration first and then to the assembly configuration. In order to design the artificial potential field for the first step, each spacecraft is outlined by an ellipse and a virtual leader of circle is introduced. The potential field mainly depends on the attitude error between the flexible spacecraft and its neighbor, the radial Euclidian distance between the ellipse and the circle and the classical Euclidian distance between the centers of the ellipse and the circle. It can be demonstrated that there are no local minima for the potential function and the global minimum is zero. If the function is equal to zero, the solution is not a certain state, but a set. All the states in the set are corresponding to the desired configurations. The Lyapunov analysis guarantees that the four spacecraft asymptotically converge to the target configuration. Moreover, the other potential field is also included to avoid the inter-member collision. In the control design of the second step, only small modification is made for the controller in the first step. Finally, the successful application of the proposed control law to the assembly mission is verified by two case studies.

  5. Computer-Automated Evolution of Spacecraft X-Band Antennas

    Science.gov (United States)

    Lohn, Jason D.; Homby, Gregory S.; Linden, Derek S.

    2010-01-01

    A document discusses the use of computer- aided evolution in arriving at a design for X-band communication antennas for NASA s three Space Technology 5 (ST5) satellites, which were launched on March 22, 2006. Two evolutionary algorithms, incorporating different representations of the antenna design and different fitness functions, were used to automatically design and optimize an X-band antenna design. A set of antenna designs satisfying initial ST5 mission requirements was evolved by use these algorithms. The two best antennas - one from each evolutionary algorithm - were built. During flight-qualification testing of these antennas, the mission requirements were changed. After minimal changes in the evolutionary algorithms - mostly in the fitness functions - new antenna designs satisfying the changed mission requirements were evolved and within one month of this change, two new antennas were designed and prototypes of the antennas were built and tested. One of these newly evolved antennas was approved for deployment on the ST5 mission, and flight-qualified versions of this design were built and installed on the spacecraft. At the time of writing the document, these antennas were the first computer-evolved hardware in outer space.

  6. Enterprise Mac Managed Preferences

    CERN Document Server

    Marczak, Edward

    2010-01-01

    Many systems administrators on the Mac need a way to manage machine configuration after initial setup and deployment. Apple's Managed Preferences system (also known as MCX) is under-documented, often misunderstood, and sometimes outright unknown by sys admins. MCX is usually deployed in conjunction with an OS X server, but it can also be used in Windows environments or where no dedicated server exists at all. Enterprise Mac Managed Preferences is the definitive guide to Apple's Managed Client technology. With this book, you'll get the following: * An example-driven guide to Mac OS X Managed Pr

  7. DOD Recovery personnel and NASA technicians inspect Friendship 7 spacecraft

    Science.gov (United States)

    1964-01-01

    Department of Defense Recovery personnel and spacecraft technicians from NASA adn McDonnell Aircraft Corp., inspect Astronaut John Glenn's Mercury spacecraft, Friendship 7, following its return to Cape Canaveral after recovery in the Atlantic Ocean.

  8. High-Performance Fire Detector for Spacecraft, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The danger from fire aboard spacecraft is immediate with only moments for detection and suppression. Spacecraft are unique high-value systems where the cost of...

  9. Nonlinear model and attitude dynamics of flexible spacecraft with large amplitude slosh

    Science.gov (United States)

    Deng, Mingle; Yue, Baozeng

    2017-04-01

    This paper is focused on the nonlinearly modelling and attitude dynamics of spacecraft coupled with large amplitude liquid sloshing dynamics and flexible appendage vibration. The large amplitude fuel slosh dynamics is included by using an improved moving pulsating ball model. The moving pulsating ball model is an equivalent mechanical model that is capable of imitating the whole liquid reorientation process. A modification is introduced in the capillary force computation in order to more precisely estimate the settling location of liquid in microgravity or zero-g environment. The flexible appendage is modelled as a three dimensional Bernoulli-Euler beam and the assumed modal method is employed to derive the nonlinear mechanical model for the overall coupled system of liquid filled spacecraft with appendage. The attitude maneuver is implemented by the momentum transfer technique, and a feedback controller is designed. The simulation results show that the liquid sloshing can always result in nutation behavior, but the effect of flexible deformation of appendage depends on the amplitude and direction of attitude maneuver performed by spacecraft. Moreover, it is found that the liquid sloshing and the vibration of flexible appendage are coupled with each other, and the coupling becomes more significant with more rapid motion of spacecraft. This study reveals that the appendage's flexibility has influence on the liquid's location and settling time in microgravity. The presented nonlinear system model can provide an important reference for the overall design of the modern spacecraft composed of rigid platform, liquid filled tank and flexible appendage.

  10. Air Purification in Closed Environments: An Overview of Spacecraft Systems

    Science.gov (United States)

    Perry, Jay L.; LeVan, Douglas; Crumbley, Robert (Technical Monitor)

    2002-01-01

    The primary goal for a collective protection system and a spacecraft environmental control and life support system (ECLSS) are strikingly similar. Essentially both function to provide the occupants of a building or vehicle with a safe, habitable environment. The collective protection system shields military and civilian personnel from short-term exposure to external threats presented by toxic agents and industrial chemicals while an ECLSS sustains astronauts for extended periods within the hostile environment of space. Both have air quality control similarities with various aircraft and 'tight' buildings. This paper reviews basic similarities between air purification system requirements for collective protection and an ECLSS that define surprisingly common technological challenges and solutions. Systems developed for air revitalization on board spacecraft are discussed along with some history on their early development as well as a view of future needs. Emphasis is placed upon two systems implemented by the National Aeronautics and Space Administration (NASA) onboard the International Space Station (ISS): the trace contaminant control system (TCCS) and the molecular sieve-based carbon dioxide removal assembly (CDRA). Over its history, the NASA has developed and implemented many life support systems for astronauts. As the duration, complexity, and crew size of manned missions increased from minutes or hours for a single astronaut during Project Mercury to days and ultimately months for crews of 3 or more during the Apollo, Skylab, Shuttle, and ISS programs, these systems have become more sophisticated. Systems aboard spacecraft such as the ISS have been designed to provide long-term environmental control and life support. Challenges facing the NASA's efforts include minimizing mass, volume, and power for such systems, while maximizing their safety, reliability, and performance. This paper will highlight similarities and differences among air purification systems

  11. Omni-directional Particle Detector (ODPD) on Tiangong-2 Spacecraft

    Science.gov (United States)

    Guohong, S.; Zhang, S.; Yang, X.; Wang, C.

    2017-12-01

    Tiangong-2 spacecraft is the second space laboratory independently developed by china after Tiangong-1, which was launched on 15 September 2016. It is also the first real space laboratory in china, which will be used to further validate the space rendezvous and docking technology and to carry out a series of space tests. The spacecraft's orbit is 350km height and 42° inclination. The omni-directional particle detector (ODPD) on Tiangong-2 spacecraft is a new instrument developed by China. Its goal is the anisotropy and energy spectra of space particles on manned space flight orbit. The ODPD measures the energy spectra and pitch angle distributions of high energy electrons and protons. It consists of one electron spectrum telescope, one proton spectrum telescope and sixteen directional flux telescopes. The ODPD is designed to measure the protons spectrum from 2.5MeV to 150MeV, electrons spectrum from 0.2MeV to 1.5MeV, the flux of electrons energy >200keV and protons energy>1.5MeV on 2∏ space, also the ODPD has a small sensor to measure the LET spectrum from 1-100MeV/cm2sr. The primary advantage can give the particle's pitch angle distributions at any time because of the sixteen flux telescopes arrange form 0 to 180 degree. This is the first paper dealing with ODPD data, so we firstly spend some time describing the instrument, its theory of operation and its calibration. Then we give the preliminary detecting results.

  12. Space tribology: its role in spacecraft mechanisms

    International Nuclear Information System (INIS)

    Roberts, E W

    2012-01-01

    The subject of tribology encompasses the friction, wear and lubrication of mechanical components such as bearings and gears. Tribological practices are aimed at ensuring that such components operate with high efficiency (low friction) and achieve long lives. On spacecraft mechanisms the route to achieving these goals brings its own unique challenges. This review describes the problems posed by the space environment, the types of tribological component used on spacecraft and the approaches taken to their lubrication. It is shown that in many instances lubrication needs can be met by synthetic oils having exceedingly low volatilities, but that at temperature extremes the only means of reducing friction and wear is by solid lubrication. As the demands placed on space engineering increase, innovatory approaches will be needed to solve future tribological problems. The direction that future developments might take is anticipated and discussed.

  13. Improved techniques for predicting spacecraft power

    International Nuclear Information System (INIS)

    Chmielewski, A.B.

    1987-01-01

    Radioisotope Thermoelectric Generators (RTGs) are going to supply power for the NASA Galileo and Ulysses spacecraft now scheduled to be launched in 1989 and 1990. The duration of the Galileo mission is expected to be over 8 years. This brings the total RTG lifetime to 13 years. In 13 years, the RTG power drops more than 20 percent leaving a very small power margin over what is consumed by the spacecraft. Thus it is very important to accurately predict the RTG performance and be able to assess the magnitude of errors involved. The paper lists all the error sources involved in the RTG power predictions and describes a statistical method for calculating the tolerance

  14. Data combinations accounting for LISA spacecraft motion

    International Nuclear Information System (INIS)

    Shaddock, Daniel A.; Tinto, Massimo; Estabrook, Frank B.; Armstrong, J.W.

    2003-01-01

    The laser interferometer space antenna is an array of three spacecraft in an approximately equilateral triangle configuration which will be used as a low-frequency gravitational wave detector. We present here new generalizations of the Michelson- and Sagnac-type time-delay interferometry data combinations. These combinations cancel laser phase noise in the presence of different up and down propagation delays in each arm of the array, and slowly varying systematic motion of the spacecraft. The gravitational wave sensitivities of these generalized combinations are the same as previously computed for the stationary cases, although the combinations are now more complicated. We introduce a diagrammatic representation to illustrate that these combinations are actually synthesized equal-arm interferometers

  15. The Stardust spacecraft arrives at KSC

    Science.gov (United States)

    1998-01-01

    After arrival at the Shuttle Landing Facility in the early morning hours, the crated Stardust spacecraft waits to be unloaded from the aircraft. Built by Lockheed Martin Astronautics near Denver, Colo., for the Jet Propulsion Laboratory (JPL) NASA, the spacecraft Stardust will use a unique medium called aerogel to capture comet particles flying off the nucleus of comet Wild 2 in January 2004, plus collect interstellar dust for later analysis. Stardust will be launched aboard a Boeing Delta 7426 rocket from Complex 17, Cape Canaveral Air Station, targeted for Feb. 6, 1999. The collected samples will return to Earth in a re- entry capsule to be jettisoned from Stardust as it swings by in January 2006.

  16. Close-Range Photogrammetry & Next Generation Spacecraft

    Science.gov (United States)

    Pappa, Richard S.

    2002-01-01

    NASA is focusing renewed attention on the topic of large, ultra-lightweight space structures, also known as 'gossamer' spacecraft. Nearly all of the details of the giant spacecraft are still to be worked out. But it's already clear that one of the most challenging aspects will be developing techniques to align and control these systems after they are deployed in space. A critical part of this process is creating new ground test methods to measure gossamer structures under stationary, deploying and vibrating conditions for validation of corresponding analytical predictions. In addressing this problem, I considered, first of all, the possibility of simply using conventional displacement or vibration sensor that could provide spatial measurements. Next, I turned my attention to photogrammetry, a method of determining the spatial coordinates of objects using photographs. The success of this research and development has convinced me that photogrammetry is the most suitable method to solve the gossamer measurement problem.

  17. Large Scale Experiments on Spacecraft Fire Safety

    DEFF Research Database (Denmark)

    Urban, David L.; Ruff, Gary A.; Minster, Olivier

    2012-01-01

    -based microgravity facilities or has been limited to very small fuel samples. Still, the work conducted to date has shown that fire behaviour in low-gravity is very different from that in normal-gravity, with differences observed for flammability limits, ignition delay, flame spread behaviour, flame colour and flame......Full scale fire testing complemented by computer modelling has provided significant knowhow about the risk, prevention and suppression of fire in terrestrial systems (cars, ships, planes, buildings, mines, and tunnels). In comparison, no such testing has been carried out for manned spacecraft due...... to the complexity, cost and risk associ-ated with operating a long duration fire safety experiment of a relevant size in microgravity. Therefore, there is currently a gap in knowledge of fire behaviour in spacecraft. The entire body of low-gravity fire research has either been conducted in short duration ground...

  18. Evaluation of Ultrafiltration for Spacecraft Water Reuse

    Science.gov (United States)

    Pickering, Karen D.; Wiesner, Mark R.

    2001-01-01

    Ultrafiltration is examined for use as the first stage of a primary treatment process for spacecraft wastewater. It is hypothesized that ultrafiltration can effectively serve as pretreatment for a reverse osmosis system, removing the majority of organic material in a spacecraft wastewater. However, it is believed that the interaction between the membrane material and the surfactant found in the wastewater will have a significant impact on the fouling of the ultrafiltration membrane. In this study, five different ultrafiltration membrane materials are examined for the filtration of wastewater typical of that expected to be produced onboard the International Space Station. Membranes are used in an unstirred batch cell. Flux, organic carbon rejection, and recovery from fouling are measured. The results of this evaluation will be used to select the most promising membranes for further study.

  19. FORTE spacecraft vibration mitigation. Final report

    International Nuclear Information System (INIS)

    Maly, J.R.

    1996-02-01

    This report documents work that was performed by CSA Engineering, Inc., for Los Alamos National Laboratory (LANL), to reduce vibrations of the FORTE spacecraft by retrofitting damped structural components into the spacecraft structure. The technical objective of the work was reduction of response at the location of payload components when the structure is subjected to the dynamic loading associated with launch and proto-qualification testing. FORTE is a small satellite that will be placed in orbit in 1996. The structure weighs approximately 425 lb, and is roughly 80 inches high and 40 inches in diameter. It was developed and built by LANL in conjunction with Sandia National Laboratories Albuquerque for the United States Department of Energy. The FORTE primary structure was fabricated primarily with graphite epoxy, using aluminum honeycomb core material for equipment decks and solar panel substrates. Equipment decks were bonded and bolted through aluminum mounting blocks to adjoining structure

  20. Consumer preference models: fuzzy theory approach

    Science.gov (United States)

    Turksen, I. B.; Wilson, I. A.

    1993-12-01

    Consumer preference models are widely used in new product design, marketing management, pricing and market segmentation. The purpose of this article is to develop and test a fuzzy set preference model which can represent linguistic variables in individual-level models implemented in parallel with existing conjoint models. The potential improvements in market share prediction and predictive validity can substantially improve management decisions about what to make (product design), for whom to make it (market segmentation) and how much to make (market share prediction).

  1. Redundancy for electric motors in spacecraft applications

    Science.gov (United States)

    Smith, Robert J.; Flew, Alastair R.

    1986-01-01

    The parts of electric motors which should be duplicated in order to provide maximum reliability in spacecraft application are identified. Various common types of redundancy are described. The advantages and disadvantages of each are noted. The principal types are illustrated by reference to specific examples. For each example, constructional details, basic performance data and failure modes are described, together with a discussion of the suitability of particular redundancy techniques to motor types.

  2. Schema for Spacecraft-Command Dictionary

    Science.gov (United States)

    Laubach, Sharon; Garcia, Celina; Maxwell, Scott; Wright, Jesse

    2008-01-01

    An Extensible Markup Language (XML) schema was developed as a means of defining and describing a structure for capturing spacecraft command- definition and tracking information in a single location in a form readable by both engineers and software used to generate software for flight and ground systems. A structure defined within this schema is then used as the basis for creating an XML file that contains command definitions.

  3. Additive Manufacturing: Ensuring Quality for Spacecraft Applications

    Science.gov (United States)

    Swanson, Theodore; Stephenson, Timothy

    2014-01-01

    Reliable manufacturing requires that material properties and fabrication processes be well defined in order to insure that the manufactured parts meet specified requirements. While this issue is now relatively straightforward for traditional processes such as subtractive manufacturing and injection molding, this capability is still evolving for AM products. Hence, one of the principal challenges within AM is in qualifying and verifying source material properties and process control. This issue is particularly critical for applications in harsh environments and demanding applications, such as spacecraft.

  4. Wheel speed management control system for spacecraft

    Science.gov (United States)

    Goodzeit, Neil E. (Inventor); Linder, David M. (Inventor)

    1991-01-01

    A spacecraft attitude control system uses at least four reaction wheels. In order to minimize reaction wheel speed and therefore power, a wheel speed management system is provided. The management system monitors the wheel speeds and generates a wheel speed error vector. The error vector is integrated, and the error vector and its integral are combined to form a correction vector. The correction vector is summed with the attitude control torque command signals for driving the reaction wheels.

  5. The Manned Spacecraft Center and medical technology

    Science.gov (United States)

    Johnston, R. S.; Pool, S. L.

    1974-01-01

    A number of medically oriented research and hardware development programs in support of manned space flights have been sponsored by NASA. Blood pressure measuring systems for use in spacecraft are considered. In some cases, complete new bioinstrumentation systems were necessary to accomplish a specific physiological study. Plans for medical research during the Skylab program are discussed along with general questions regarding space-borne health service systems and details concerning the Health Services Support Control Center.

  6. Artificial Intelligence and Spacecraft Power Systems

    Science.gov (United States)

    Dugel-Whitehead, Norma R.

    1997-01-01

    This talk will present the work which has been done at NASA Marshall Space Flight Center involving the use of Artificial Intelligence to control the power system in a spacecraft. The presentation will include a brief history of power system automation, and some basic definitions of the types of artificial intelligence which have been investigated at MSFC for power system automation. A video tape of one of our autonomous power systems using co-operating expert systems, and advanced hardware will be presented.

  7. THE FUTURE OF SPACECRAFT NUCLEAR PROPULSION

    OpenAIRE

    Jansen, Frank

    2014-01-01

    This paper summarizes the advantages of space nuclear power and propulsion systems. It describes the actual status of international power level dependent spacecraft nuclear propulsion missions, especially the high power EU-Russian MEGAHIT study including the Russian Megawatt-Class Nuclear Power Propulsion System, the NASA GRC project and the low and medium power EU DiPoP study. Space nuclear propulsion based mission scenarios of these studies are sketched as well.

  8. Flexible spacecraft dynamics, control and guidance technologies by giovanni campolo

    CERN Document Server

    Mazzini, Leonardo

    2016-01-01

    This book is an up-to-date compendium on spacecraft attitude and orbit control (AOC) that offers a systematic and complete treatment of the subject with the aim of imparting the theoretical and practical knowledge that is required by designers, engineers, and researchers. After an introduction on the kinematics of the flexible and agile space vehicles, the modern architecture and functions of an AOC system are described and the main AOC modes reviewed with possible design solutions and examples. The dynamics of the flexible body in space are then considered using an original Lagrangian approach suitable for the control applications of large space flexible structures. Subsequent chapters address optimal control theory, attitude control methods, and orbit control applications, including the optimal orbital transfer with finite and infinite thrust. The theory is integrated with a description of current propulsion systems, with the focus especially on the new electric propulsion systems and state of the art senso...

  9. Integration of a Fire Detector into a Spacecraft

    Science.gov (United States)

    Linford, R. M. F.

    1972-01-01

    A detector sensitive to only the ultraviolet radiation emitted by flames has been selected as the basic element of the NASA Skylab fire detection system. It is sensitive to approximately 10(exp -12)W of radiation and will detect small flames at distances in excess of 3m. The performance of the detector was verified by experiments in an aircraft flying zero-gravity parabolas to simulate the characteristics of a fire which the detector must sense. Extensive investigation and exacting design was necessary to exclude all possible sources of false alarms. Optical measurements were made on all the spacecraft windows to determine the amount of solar radiation transmitted. The lighting systems and the onboard experiments also were appraised for ultraviolet emissions. Proton-accelerator tests were performed to determine the interaction of the Earth's trapped radiation belts with the detectors and the design of the instrument was modified to negate these effects.

  10. MESA - A new approach to low cost scientific spacecraft

    Science.gov (United States)

    Keyes, G. W.; Case, C. M.

    1982-09-01

    Today, the greatest obstacle to science and exploration in space is its cost. The present investigation is concerned with approaches for reducing this cost. Trends in the scientific spacecraft market are examined, and a description is presented for the MESA space platform concept. The cost drivers are considered, taking into account planning, technical aspects, and business factors. It is pointed out that the primary function of the MESA concept is to provide a satellite system at the lowest possible price. In order to reach this goal an attempt is made to benefit from all of the considered cost drivers. It is to be tried to work with the customer early in the mission analysis stage in order to assist in finding the right compromise between mission cost and return. A three phase contractual arrangement is recommended for MESA platforms. The phases are related to mission feasibility, specification definition, and design and development. Modular kit design promotes flexibility at low cost.

  11. Determination of Realistic Fire Scenarios in Spacecraft

    Science.gov (United States)

    Dietrich, Daniel L.; Ruff, Gary A.; Urban, David

    2013-01-01

    This paper expands on previous work that examined how large a fire a crew member could successfully survive and extinguish in the confines of a spacecraft. The hazards to the crew and equipment during an accidental fire include excessive pressure rise resulting in a catastrophic rupture of the vehicle skin, excessive temperatures that burn or incapacitate the crew (due to hyperthermia), carbon dioxide build-up or accumulation of other combustion products (e.g. carbon monoxide). The previous work introduced a simplified model that treated the fire primarily as a source of heat and combustion products and sink for oxygen prescribed (input to the model) based on terrestrial standards. The model further treated the spacecraft as a closed system with no capability to vent to the vacuum of space. The model in the present work extends this analysis to more realistically treat the pressure relief system(s) of the spacecraft, include more combustion products (e.g. HF) in the analysis and attempt to predict the fire spread and limiting fire size (based on knowledge of terrestrial fires and the known characteristics of microgravity fires) rather than prescribe them in the analysis. Including the characteristics of vehicle pressure relief systems has a dramatic mitigating effect by eliminating vehicle overpressure for all but very large fires and reducing average gas-phase temperatures.

  12. Probing interferometric parallax with interplanetary spacecraft

    Science.gov (United States)

    Rodeghiero, G.; Gini, F.; Marchili, N.; Jain, P.; Ralston, J. P.; Dallacasa, D.; Naletto, G.; Possenti, A.; Barbieri, C.; Franceschini, A.; Zampieri, L.

    2017-07-01

    We describe an experimental scenario for testing a novel method to measure distance and proper motion of astronomical sources. The method is based on multi-epoch observations of amplitude or intensity correlations between separate receiving systems. This technique is called Interferometric Parallax, and efficiently exploits phase information that has traditionally been overlooked. The test case we discuss combines amplitude correlations of signals from deep space interplanetary spacecraft with those from distant galactic and extragalactic radio sources with the goal of estimating the interplanetary spacecraft distance. Interferometric parallax relies on the detection of wavefront curvature effects in signals collected by pairs of separate receiving systems. The method shows promising potentialities over current techniques when the target is unresolved from the background reference sources. Developments in this field might lead to the construction of an independent, geometrical cosmic distance ladder using a dedicated project and future generation instruments. We present a conceptual overview supported by numerical estimates of its performances applied to a spacecraft orbiting the Solar System. Simulations support the feasibility of measurements with a simple and time-saving observational scheme using current facilities.

  13. On-orbit supervisor for controlling spacecraft

    Science.gov (United States)

    Vandervoort, Richard J.

    1992-07-01

    Spacecraft systems of the 1990's and beyond will be substantially more complex than their predecessors. They will have demanding performance requirements and will be expected to operate more autonomously. This underscores the need for innovative approaches to Fault Detection, Isolation and Recovery (FDIR). A hierarchical expert system is presented that provides on-orbit supervision using intelligent FDIR techniques. Each expert system in the hierarchy supervises the operation of a local set of spacecraft functions. Spacecraft operational goals flow top down while responses flow bottom up. The expert system supervisors have a fairly high degree of autonomy. Bureaucratic responsibilities are minimized to conserve bandwidth and maximize response time. Data for FDIR can be acquired local to an expert and from other experts. By using a blackboard architecture for each supervisor, the system provides a great degree of flexibility in implementing the problem solvers for each problem domain. In addition, it provides for a clear separation between facts and knowledge, leading to an efficient system capable of real time response.

  14. Delamination Assessment Tool for Spacecraft Composite Structures

    Science.gov (United States)

    Portela, Pedro; Preller, Fabian; Wittke, Henrik; Sinnema, Gerben; Camanho, Pedro; Turon, Albert

    2012-07-01

    Fortunately only few cases are known where failure of spacecraft structures due to undetected damage has resulted in a loss of spacecraft and launcher mission. However, several problems related to damage tolerance and in particular delamination of composite materials have been encountered during structure development of various ESA projects and qualification testing. To avoid such costly failures during development, launch or service of spacecraft, launcher and reusable launch vehicles structures a comprehensive damage tolerance verification approach is needed. In 2009, the European Space Agency (ESA) initiated an activity called “Delamination Assessment Tool” which is led by the Portuguese company HPS Lda and includes academic and industrial partners. The goal of this study is the development of a comprehensive damage tolerance verification approach for launcher and reusable launch vehicles (RLV) structures, addressing analytical and numerical methodologies, material-, subcomponent- and component testing, as well as non-destructive inspection. The study includes a comprehensive review of current industrial damage tolerance practice resulting from ECSS and NASA standards, the development of new Best Practice Guidelines for analysis, test and inspection methods and the validation of these with a real industrial case study. The paper describes the main findings of this activity so far and presents a first iteration of a Damage Tolerance Verification Approach, which includes the introduction of novel analytical and numerical tools at an industrial level. This new approach is being put to the test using real industrial case studies provided by the industrial partners, MT Aerospace, RUAG Space and INVENT GmbH

  15. Immigrants' location preferences

    DEFF Research Database (Denmark)

    Damm, Anna Piil

    This paper exploits a spatial dispersal policy for refugee immigrants to estimate the importance of local and regional factors for refugees' location preferences. The main results of a mixed proportional hazard competing risks model are that placed refugees react to high regional unemployment...

  16. Hormones and social preferences

    NARCIS (Netherlands)

    Buser, T.

    2011-01-01

    We examine whether social preferences are determined by hormones. We do this by investigating whether markers for the strength of prenatal testosterone exposure (finger length ratios) and current exposure to progesterone and oxytocin (the menstrual cycle) are correlated with choices in social

  17. Preferred Dance Tempo

    DEFF Research Database (Denmark)

    Dahl, Sofia; Huron, David; Brod, Garvin

    2014-01-01

    In two experiments participants tuned a drum machine to their preferred dance tempo. Measurements of height, shoulder width, leg length, and weight were taken for each participant, and their sex recorded. Using a multiple regression analysis, height and leg length combined was found to be the bes...

  18. Advanced composite design data for spacecraft structural applications

    International Nuclear Information System (INIS)

    Haskins, J.F.

    1980-01-01

    An experimental study has been carried out to investigate the long-term effects of space environment on the mechanical properties and thermal expansion of two graphite/epoxy materials: T300/934, a high-strength system with a 350 F capability, and GY70/X30, an ultra-high-modulus system used for high-stiffness and thermally stable applications. The effects of space environment were simulated by exposing the materials to three levels of uniform radiation. Changes in mechanical properties due to radiation were small, except at high temperatures. Since radiation clearly lowered the glass transition temperature below the upper test temperature, both tensile and shear strengths were lowered at the elevated temperatures. There was also some indication that the lower radiation levels may even improve the mechanical properties, which however needs further investigation

  19. Design and Experimental Implementation of Optimal Spacecraft Antenna Slews

    Science.gov (United States)

    2013-12-01

    2.5) It is important to note that Equation (2.5) assumes there is no momentum storage in the system, such as reaction wheels . The torque term in...problem definition: TDRS ISS NOAA‐15 Worldview‐2 MEO Semi‐Major Axis (km) 42166.41 6787.36 7173.81 7150.06 16678.14 Eccentricity 0.001014 0.001563

  20. Rapid Onboard Trajectory Design for Autonomous Spacecraft in Multibody Systems

    Science.gov (United States)

    Trumbauer, Eric Michael

    This research develops automated, on-board trajectory planning algorithms in order to support current and new mission concepts. These include orbiter missions to Phobos or Deimos, Outer Planet Moon orbiters, and robotic and crewed missions to small bodies. The challenges stem from the limited on-board computing resources which restrict full trajectory optimization with guaranteed convergence in complex dynamical environments. The approach taken consists of leveraging pre-mission computations to create a large database of pre-computed orbits and arcs. Such a database is used to generate a discrete representation of the dynamics in the form of a directed graph, which acts to index these arcs. This allows the use of graph search algorithms on-board in order to provide good approximate solutions to the path planning problem. Coupled with robust differential correction and optimization techniques, this enables the determination of an efficient path between any boundary conditions with very little time and computing effort. Furthermore, the optimization methods developed here based on sequential convex programming are shown to have provable convergence properties, as well as generating feasible major iterates in case of a system interrupt -- a key requirement for on-board application. The outcome of this project is thus the development of an algorithmic framework which allows the deployment of this approach in a variety of specific mission contexts. Test cases related to missions of interest to NASA and JPL such as a Phobos orbiter and a Near Earth Asteroid interceptor are demonstrated, including the results of an implementation on the RAD750 flight processor. This method fills a gap in the toolbox being developed to create fully autonomous space exploration systems.

  1. Design of Attitude Control Actuators for a Simulated Spacecraft

    Science.gov (United States)

    2011-03-24

    however, there are many dual-use applications, such as regenerative braking technology and flywheel energy storage. The reaction wheel system on Simsat...as the reaction wheels change angular velocity. 2.3.5 Control Moment Gyroscopes. The second category of momentum ex- change devices is the control

  2. Controller Design for Accurate Antenna Pointing Onboard a Spacecraft

    National Research Council Canada - National Science Library

    Barba, Victor M

    2007-01-01

    .... Simulations are conducted to show that the integration of feedforward control action and feedback compensation produces better responses than the implementation of either individual control system...

  3. A Survey of Cost Estimating Methodologies for Distributed Spacecraft Missions

    Science.gov (United States)

    Foreman, Veronica L.; Le Moigne, Jacqueline; de Weck, Oliver

    2016-01-01

    Satellite constellations present unique capabilities and opportunities to Earth orbiting and near-Earth scientific and communications missions, but also present new challenges to cost estimators. An effective and adaptive cost model is essential to successful mission design and implementation, and as Distributed Spacecraft Missions (DSM) become more common, cost estimating tools must become more representative of these types of designs. Existing cost models often focus on a single spacecraft and require extensive design knowledge to produce high fidelity estimates. Previous research has examined the limitations of existing cost practices as they pertain to the early stages of mission formulation, for both individual satellites and small satellite constellations. Recommendations have been made for how to improve the cost models for individual satellites one-at-a-time, but much of the complexity in constellation and DSM cost modeling arises from constellation systems level considerations that have not yet been examined. This paper constitutes a survey of the current state-of-theart in cost estimating techniques with recommendations for improvements to increase the fidelity of future constellation cost estimates. To enable our investigation, we have developed a cost estimating tool for constellation missions. The development of this tool has revealed three high-priority shortcomings within existing parametric cost estimating capabilities as they pertain to DSM architectures: design iteration, integration and test, and mission operations. Within this paper we offer illustrative examples of these discrepancies and make preliminary recommendations for addressing them. DSM and satellite constellation missions are shifting the paradigm of space-based remote sensing, showing promise in the realms of Earth science, planetary observation, and various heliophysical applications. To fully reap the benefits of DSM technology, accurate and relevant cost estimating capabilities

  4. The Glory Program: Global Science from a Unique Spacecraft Integration

    Science.gov (United States)

    Bajpayee Jaya; Durham, Darcie; Ichkawich, Thomas

    2006-01-01

    The Glory program is an Earth and Solar science mission designed to broaden science community knowledge of the environment. The causes and effects of global warming have become a concern in recent years and Glory aims to contribute to the knowledge base of the science community. Glory is designed for two functions: one is solar viewing to monitor the total solar irradiance and the other is observing the Earth s atmosphere for aerosol composition. The former is done with an active cavity radiometer, while the latter is accomplished with an aerosol polarimeter sensor to discern atmospheric particles. The Glory program is managed by NASA Goddard Space Flight Center (GSFC) with Orbital Sciences in Dulles, VA as the prime contractor for the spacecraft bus, mission operations, and ground system. This paper will describe some of the more unique features of the Glory program including the integration and testing of the satellite and instruments as well as the science data processing. The spacecraft integration and test approach requires extensive analysis and additional planning to ensure existing components are successfully functioning with the new Glory components. The science mission data analysis requires development of mission unique processing systems and algorithms. Science data analysis and distribution will utilize our national assets at the Goddard Institute for Space Studies (GISS) and the University of Colorado's Laboratory for Atmospheric and Space Physics (LASP). The Satellite was originally designed and built for the Vegetation Canopy Lidar (VCL) mission, which was terminated in the middle of integration and testing due to payload development issues. The bus was then placed in secure storage in 2001 and removed from an environmentally controlled container in late 2003 to be refurbished to meet the Glory program requirements. Functional testing of all the components was done as a system at the start of the program, very different from a traditional program

  5. Comprehensive Fault Tolerance and Science-Optimal Attitude Planning for Spacecraft Applications

    Science.gov (United States)

    Nasir, Ali

    behavior of computed policies in response to the changes in design parameters. A primary case study is built from the Far Ultraviolet Spectroscopic Explorer (FUSE) mission for which component models and their probabilities of failure are based on realistic mission data. A comparison of our approach with an alternative framework for spacecraft task planning and fault management is presented in the context of the FUSE mission.

  6. Large Scale Experiments on Spacecraft Fire Safety

    Science.gov (United States)

    Urban, David; Ruff, Gary A.; Minster, Olivier; Fernandez-Pello, A. Carlos; Tien, James S.; Torero, Jose L.; Legros, Guillaume; Eigenbrod, Christian; Smirnov, Nickolay; Fujita, Osamu; hide

    2012-01-01

    Full scale fire testing complemented by computer modelling has provided significant knowhow about the risk, prevention and suppression of fire in terrestrial systems (cars, ships, planes, buildings, mines, and tunnels). In comparison, no such testing has been carried out for manned spacecraft due to the complexity, cost and risk associated with operating a long duration fire safety experiment of a relevant size in microgravity. Therefore, there is currently a gap in knowledge of fire behaviour in spacecraft. The entire body of low-gravity fire research has either been conducted in short duration ground-based microgravity facilities or has been limited to very small fuel samples. Still, the work conducted to date has shown that fire behaviour in low-gravity is very different from that in normal gravity, with differences observed for flammability limits, ignition delay, flame spread behaviour, flame colour and flame structure. As a result, the prediction of the behaviour of fires in reduced gravity is at present not validated. To address this gap in knowledge, a collaborative international project, Spacecraft Fire Safety, has been established with its cornerstone being the development of an experiment (Fire Safety 1) to be conducted on an ISS resupply vehicle, such as the Automated Transfer Vehicle (ATV) or Orbital Cygnus after it leaves the ISS and before it enters the atmosphere. A computer modelling effort will complement the experimental effort. Although the experiment will need to meet rigorous safety requirements to ensure the carrier vehicle does not sustain damage, the absence of a crew removes the need for strict containment of combustion products. This will facilitate the possibility of examining fire behaviour on a scale that is relevant to spacecraft fire safety and will provide unique data for fire model validation. This unprecedented opportunity will expand the understanding of the fundamentals of fire behaviour in spacecraft. The experiment is being

  7. Studies of Fission Fragment Rocket Engine Propelled Spacecraft

    Science.gov (United States)

    Werka, Robert O.; Clark, Rodney; Sheldon, Rob; Percy, Thomas K.

    2014-01-01

    The NASA Office of Chief Technologist has funded from FY11 through FY14 successive studies of the physics, design, and spacecraft integration of a Fission Fragment Rocket Engine (FFRE) that directly converts the momentum of fission fragments continuously into spacecraft momentum at a theoretical specific impulse above one million seconds. While others have promised future propulsion advances if only you have the patience, the FFRE requires no waiting, no advances in physics and no advances in manufacturing processes. Such an engine unequivocally can create a new era of space exploration that can change spacecraft operation. The NIAC (NASA Institute for Advanced Concepts) Program Phase 1 study of FY11 first investigated how the revolutionary FFRE technology could be integrated into an advanced spacecraft. The FFRE combines existent technologies of low density fissioning dust trapped electrostatically and high field strength superconducting magnets for beam management. By organizing the nuclear core material to permit sufficient mean free path for escape of the fission fragments and by collimating the beam, this study showed the FFRE could convert nuclear power to thrust directly and efficiently at a delivered specific impulse of 527,000 seconds. The FY13 study showed that, without increasing the reactor power, adding a neutral gas to the fission fragment beam significantly increased the FFRE thrust through in a manner analogous to a jet engine afterburner. This frictional interaction of gas and beam resulted in an engine that continuously produced 1000 pound force of thrust at a delivered impulse of 32,000 seconds, thereby reducing the currently studied DRM 5 round trip mission to Mars from 3 years to 260 days. By decreasing the gas addition, this same engine can be tailored for much lower thrust at much higher impulse to match missions to more distant destinations. These studies created host spacecraft concepts configured for manned round trip journeys. While the

  8. Performance of silvered Teflon (trademark) thermal control blankets on spacecraft

    Science.gov (United States)

    Pippin, Gary; Stuckey, Wayne; Hemminger, Carol

    1993-01-01

    Silverized Teflon (Ag/FEP) is a widely used passive thermal control material for space applications. The material has a very low alpha/e ratio (less than 0.1) for low operating temperatures and is fabricated with various FEP thicknesses (as the Teflon thickness increases, the emittance increases). It is low outgassing and, because of its flexibility, can be applied around complex, curved shapes. Ag/FEP has achieved multiyear lifetimes under a variety of exposure conditions. This has been demonstrated by the Long Duration Exposure Facility (LDEF), Solar Max, Spacecraft Charging at High Altitudes (SCATHA), and other flight experiments. Ag/FEP material has been held in place on spacecraft by a variety of methods: mechanical clamping, direct adhesive bonding of tapes and sheets, and by Velcro(TM) tape adhesively bonded to back surfaces. On LDEF, for example, 5-mil blankets held by Velcro(TM) and clamping were used for thermal control over 3- by 4-ft areas on each of 17 trays. Adhesively bonded 2- and 5-mil sheets were used on other LDEF experiments, both for thermal control and as tape to hold other thermal control blankets in place. Performance data over extended time periods are available from a number of flights. The observed effects on optical properties, mechanical properties, and surface chemistry will be summarized in this paper. This leads to a discussion of performance life estimates and other design lessons for Ag/FEP thermal control material.

  9. Spacecraft Attitude Tracking and Maneuver Using Combined Magnetic Actuators

    Science.gov (United States)

    Zhou, Zhiqiang

    2010-01-01

    The accuracy of spacecraft attitude control using magnetic actuators only is low and on the order of 0.4-5 degrees. The key reason is that the magnetic torque is two-dimensional and it is only in the plane perpendicular to the magnetic field vector. In this paper novel attitude control algorithms using the combination of magnetic actuators with Reaction Wheel Assembles (RWAs) or other types of actuators, such as thrusters, are presented. The combination of magnetic actuators with one or two RWAs aligned with different body axis expands the two-dimensional control torque to three-dimensional. The algorithms can guarantee the spacecraft attitude and rates to track the commanded attitude precisely. A design example is presented for Nadir pointing, pitch and yaw maneuvers. The results show that precise attitude tracking can be reached and the attitude control accuracy is comparable with RWAs based attitude control. The algorithms are also useful for the RWAs based attitude control. When there are only one or two workable RWAs due to RWA failures, the attitude control system can switch to the control algorithms for the combined magnetic actuators with the RWAs without going to the safe mode and the control accuracy can be maintained.

  10. Spacecraft Attitude Tracking and Maneuver Using Combined Magnetic Actuators

    Science.gov (United States)

    Zhou, Zhiqiang

    2012-01-01

    A paper describes attitude-control algorithms using the combination of magnetic actuators with reaction wheel assemblies (RWAs) or other types of actuators such as thrusters. The combination of magnetic actuators with one or two RWAs aligned with different body axis expands the two-dimensional control torque to three-dimensional. The algorithms can guarantee the spacecraft attitude and rates to track the commanded attitude precisely. A design example is presented for nadir-pointing, pitch, and yaw maneuvers. The results show that precise attitude tracking can be reached and the attitude- control accuracy is comparable with RWA-based attitude control. When there are only one or two workable RWAs due to RWA failures, the attitude-control system can switch to the control algorithms for the combined magnetic actuators with the RWAs without going to the safe mode, and the control accuracy can be maintained. The attitude-control algorithms of the combined actuators are derived, which can guarantee the spacecraft attitude and rates to track the commanded values precisely. Results show that precise attitude tracking can be reached, and the attitude-control accuracy is comparable with 3-axis wheel control.

  11. A computer graphics system for visualizing spacecraft in orbit

    Science.gov (United States)

    Eyles, Don E.

    1989-01-01

    To carry out unanticipated operations with resources already in space is part of the rationale for a permanently manned space station in Earth orbit. The astronauts aboard a space station will require an on-board, spatial display tool to assist the planning and rehearsal of upcoming operations. Such a tool can also help astronauts to monitor and control such operations as they occur, especially in cases where first-hand visibility is not possible. A computer graphics visualization system designed for such an application and currently implemented as part of a ground-based simulation is described. The visualization system presents to the user the spatial information available in the spacecraft's computers by drawing a dynamic picture containing the planet Earth, the Sun, a star field, and up to two spacecraft. The point of view within the picture can be controlled by the user to obtain a number of specific visualization functions. The elements of the display, the methods used to control the display's point of view, and some of the ways in which the system can be used are described.

  12. Electromagnetic Spacecraft Propulsion Motor and a Permanent Magnet (PM-Drive) Thruster

    Science.gov (United States)

    Ahmadov, B. A.

    2018-04-01

    Ion thrusters are designed to be used for realization of a Mars Sample Return mission. The competing technologies with ion thrusters are electromagnetic spacecraft propulsion motors. I'm an engineer and engage in the creation of the new electromagnetic propulsion motors.

  13. Accelerated test program for sealed nickel-cadmium spacecraft batteries/cells

    Science.gov (United States)

    Goodman, L. A.

    1976-01-01

    The feasibility was examined of inducing an accelerated test on sealed Nickel-Cadmium batteries or cells as a tool for spacecraft projects and battery users to determine: (1) the prediction of life capability; (2) a method of evaluating the effect of design and component changes in cells; and (3) a means of reducing time and cost of cell testing.

  14. SMART-1: the first spacecraft of the future

    Science.gov (United States)

    2003-09-01

    This is the first of a series of missions designed to test key technologies for future spacecraft —SMART stands for 'Small Missions for Advanced Research and Technology'. In the case of SMART-1, the two main new technologies to be tested are a new 'solar-electric propulsion' system and miniaturised spacecraft and instrumentation. Together, these technologies make up a spacecraft with revolutionary qualities: smaller, lighter, capable of carrying more scientific instruments, greater fuel efficiency. All of which also considerably reduces the cost of the mission. So, the idea behind SMART-1 is to pioneer a futuristic philosophy, the motto of which could be: 'more science for less money'. Even though it is the first of a kind, SMART-1 has been developed in less than four years, and at about a fifth of the cost of a major science mission for ESA: only 110 million euros. That includes the launch, the operations and a dozen scientific experiments. This was achieved partly by using new management methods — such as working with smaller teams both within ESA and in the industry — and partly because of some of the new features inherent in SMART-1, such as the miniaturisation and novel design. Giuseppe Racca, SMART-1 Project Manager, explains: "What has been our trick? First, a short development period in itself means less money. But also, with its small size — which was a requirement of the mission because we are testing miniaturised hardware — the spacecraft is able to 'share' a commercial Ariane flight with two other passengers. Besides, since we were not constrained by any existing design or heritage, we could be more innovative and elegant in our architecture. For example, the new SMART-1 electrical architecture has enabled us to simplify the system tests considerably." SMART-1 could almost be a toy spacecraft — it weighs only 367 kilograms and fits into a cube just one metre across (the solar panel wings extend about 14 metres) — although one able to

  15. Contemporary state of spacecraft/environment interaction research

    CERN Document Server

    Novikov, L S

    1999-01-01

    Various space environment effects on spacecraft materials and equipment, and the reverse effects of spacecrafts and rockets on space environment are considered. The necessity of permanent updating and perfection of our knowledge on spacecraft/environment interaction processes is noted. Requirements imposed on models of space environment in theoretical and experimental researches of various aspects of the spacecraft/environment interaction problem are formulated. In this field, main problems which need to be solved today and in the nearest future are specified. The conclusion is made that the joint analysis of both aspects of spacecraft/environment interaction problem promotes the most effective solution of the problem.

  16. Development and Analysis of a Resource-Aware Power Management System as Applied to Small Spacecraft

    Energy Technology Data Exchange (ETDEWEB)

    Shriver, Patrick [Univ. of Colorado, Boulder, CO (United States)

    2005-01-01

    In this thesis, an overall framework and solution method for managing the limited power resources of a small spacecraft is presented. Analogous to mobile computing technology, a primary limiting factor is the available power resources. In spite of the millions of dollars budgeted for research and development over decades, improvements in battery efficiency remains low. This situation is exacerbated by advances in payload technology that lead to increasingly power-hungry and data-intensive instruments. The challenge for the small spacecraft is to maximize capabilities and performance while meeting difficult design requirements and small project budgets.

  17. Effort to recover SOHO spacecraft continue as investigation board focuses on most likely causes

    Science.gov (United States)

    1998-07-01

    Meanwhile, the ESA/NASA investigation board concentrates its inquiry on three errors that appear to have led to the interruption of communications with SOHO on June 25. Officials remain hopeful that, based on ESA's successful recovery of the Olympus spacecraft after four weeks under similar conditions in 1991, recovery of SOHO may be possible. The SOHO Mission Interruption Joint ESA/NASA Investigation Board has determined that the first two errors were contained in preprogrammed command sequences executed on ground system computers, while the last error was a decision to send a command to the spacecraft in response to unexpected telemetry readings. The spacecraft is controlled by the Flight Operations Team, based at NASA's Goddard Space Flight Center, Greenbelt, MD. The first error was in a preprogrammed command sequence that lacked a command to enable an on-board software function designed to activate a gyro needed for control in Emergency Sun Reacquisition (ESR) mode. ESR mode is entered by the spacecraft in the event of anomalies. The second error, which was in a different preprogrammed command sequence, resulted in incorrect readings from one of the spacecraft's three gyroscopes, which in turn triggered an ESR. At the current stage of the investigation, the board believes that the two anomalous command sequences, in combination with a decision to send a command to SOHO to turn off a gyro in response to unexpected telemetry values, caused the spacecraft to enter a series of ESRs, and ultimately led to the loss of control. The efforts of the investigation board are now directed at identifying the circumstances that led to the errors, and at developing a recovery plan should efforts to regain contact with the spacecraft succeed. ESA and NASA engineers believe the spacecraft is currently spinning with its solar panels nearly edge-on towards the Sun, and thus not generating any power. Since the spacecraft is spinning around a fixed axis, as the spacecraft progresses

  18. Perceived Spaciousness and Preference in Sequential Experience.

    Science.gov (United States)

    Bokharaei, Saleheh; Nasar, Jack L

    2016-11-01

    We assessed the perceived spaciousness and preference for a destination space in relation to six attributes (size, lighting, window size, texture, wall mural, and amount of furniture) of it and of the space experienced before it. Studies have examined effects of these attributes but not for dynamic experience or preference. We created 24 virtual reality walks between each possible pair of two levels of each attribute. For each destination space, 31 students (13 men, 18 women) rated spaciousness and 30 students (16 men, 14 women) rated preference. We conducted separate 2 × 2 repeated-measure ANOVAs across each condition for perceived spaciousness and preference. Participants judged the space that was larger, was more brightly lit, with a larger window, or with less furniture as the more spacious. These attributes also increased preference. Consonant with adaptation-level theory, participants judged offices as higher in spaciousness and preference if preceded by a space that was smaller, was more dimly lit, or had smaller windows. The findings suggest that perceived spaciousness varies with size, lightness, window size, and amount of furniture but that perception also depends on the size, lightness, and size of the space experienced before. Designers could use the findings to manipulate features to make a space appear larger or more desirable. © 2016, Human Factors and Ergonomics Society.

  19. Design

    DEFF Research Database (Denmark)

    Volf, Mette

    This publication is unique in its demystification and operationalization of the complex and elusive nature of the design process. The publication portrays the designer’s daily work and the creative process, which the designer is a part of. Apart from displaying the designer’s work methods...... and design parameters, the publication shows examples from renowned Danish design firms. Through these examples the reader gets an insight into the designer’s reality....

  20. The Effect of Golden Pothos in Reducing the Level of Volatile Organic Compounds in a Simulated Spacecraft Cabin

    Science.gov (United States)

    Ursprung, Matthew; Amiri, Azita; Kayatin, Matthew; Perry, Jay

    2016-01-01

    The impact of Golden Pothos on indoor air quality was studied against a simulated spacecraft trace contaminant load model, consistent with the International Space Station (ISS), containing volatile organic compounds (VOCs) and formaldehyde. Previous research provides inconclusive results on the efficacy of plant VOC removal which this projects seeks to rectify through a better experimental design. This work develops a passive system for removing common VOC's from spacecraft and household indoor air and decreasing the necessity for active cabin trace contaminant removal systems.