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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,405 records · Page 78
All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

Distributed Large Data-Object Environments: End-to-End Performance Analysis of High Speed Distributed Storage Systems in Wide Area ATM Networks

We have developed and deployed a distributed-parallel storage system (DPSS) in several high speed asynchronous transfer mode (ATM) wide area networks (WAN) testbeds to support several different types of data-intensive applications. Architecturally, the DPSS is a network striped disk array, but is fairly unique in that its implementation allows applications complete freedom to determine optimal data layout, replication and/or coding redundancy strategy, security policy, and dynamic reconfiguration. In conjunction with the DPSS, we have developed a 'top-to-bottom, end-to-end' performance monitoring and analysis methodology that has allowed us to characterize all aspects of the DPSS operating in high speed ATM networks. In particular, we have run a variety of performance monitoring experiments involving the DPSS in the MAGIC testbed, which is a large scale, high speed, ATM network and we describe our experience using the monitoring methodology to identify and correct problems that limit the performance of high speed distributed applications. Finally, the DPSS is part of an overall architecture for using high speed, WAN's for enabling the routine, location independent use of large data-objects. Since this is part of the motivation for a distributed storage system, we describe this architecture.

Johnston, William↗
NASA NTRS1997

Analysis of Technology for Solid State Coherent Lidar

Over the past few years, considerable advances have been made in the areas of the diode-pumped, eye-safe, solid state lasers, wide bandwidth, semiconductor detectors operating in the near-infrared region. These advances have created new possibilities for the development of low-cost, reliable, and compact coherent lidar systems for measurements of atmospheric winds and aerosol backscattering from a space-based platform. The work performed by the UAH personnel concentrated on design and analyses of solid state pulsed coherent lidar systems capable of measuring atmospheric winds from space, and design and perform laboratory experiments and measurements in support of solid state laser radar remote sensing systems which are to be designed, deployed, and used by NASA to measure atmospheric processes and constituents. A lidar testbed system was designed and analyzed by considering the major space operational and environmental requirements, and its associated physical constraints. The lidar optical system includes a wedge scanner and the compact telescope designed by the UAH personnel. The other major optical components included in the design and analyses were: polarizing beam splitter, routing mirrors, wave plates, signal beam derotator, and lag angle compensator. The testbed lidar optical train was designed and analyzed, and different design options for mounting and packaging the lidar subsystems and components and support structure were investigated. All the optical components are to be mounted in a stress-free and stable manner to allow easy integration and alignment, and long term stability. This lidar system is also intended to be used for evaluating the performance of various lidar subsystems and components that are to be integrated into a flight unit and for demonstrating the integrity of the signal processing algorithms by performing actual atmospheric measurements from a ground station.

Amzajerdian, Farzin↗
NASA NTRS1997

Electrolysis Propulsion for Spacecraft Applications

Electrolysis propulsion has been recognized over the last several decades as a viable option to meet many satellite and spacecraft propulsion requirements. This technology, however, was never used for in-space missions. In the same time frame, water based fuel cells have flown in a number of missions. These systems have many components similar to electrolysis propulsion systems. Recent advances in component technology include: lightweight tankage, water vapor feed electrolysis, fuel cell technology, and thrust chamber materials for propulsion. Taken together, these developments make propulsion and/or power using electrolysis/fuel cell technology very attractive as separate or integrated systems. A water electrolysis propulsion testbed was constructed and tested in a joint NASA/Hamilton Standard/Lawrence Livermore National Laboratories program to demonstrate these technology developments for propulsion. The results from these testbed experiments using a I-N thruster are presented. A concept to integrate a propulsion system and a fuel cell system into a unitized spacecraft propulsion and power system is outlined.

deGroot, Wim A.↗
NASA NTRS1997

[Advanced Development for Space Robotics With Emphasis on Fault Tolerance Technology]

This report describes work developing fault tolerant redundant robotic architectures and adaptive control strategies for robotic manipulator systems which can dynamically accommodate drastic robot manipulator mechanism, sensor or control failures and maintain stable end-point trajectory control with minimum disturbance. Kinematic designs of redundant, modular, reconfigurable arms for fault tolerance were pursued at a fundamental level. The approach developed robotic testbeds to evaluate disturbance responses of fault tolerant concepts in robotic mechanisms and controllers. The development was implemented in various fault tolerant mechanism testbeds including duality in the joint servo motor modules, parallel and serial structural architectures, and dual arms. All have real-time adaptive controller technologies to react to mechanism or controller disturbances (failures) to perform real-time reconfiguration to continue the task operations. The developments fall into three main areas: hardware, software, and theoretical.

Tesar, Delbert↗
NASA NTRS1997

BACT Simulation User Guide (Version 7.0)

This report documents the structure and operation of a simulation model of the Benchmark Active Control Technology (BACT) Wind-Tunnel Model. The BACT system was designed, built, and tested at NASA Langley Research Center as part of the Benchmark Models Program and was developed to perform wind-tunnel experiments to obtain benchmark quality data to validate computational fluid dynamics and computational aeroelasticity codes, to verify the accuracy of current aeroservoelasticity design and analysis tools, and to provide an active controls testbed for evaluating new and innovative control algorithms for flutter suppression and gust load alleviation. The BACT system has been especially valuable as a control system testbed.

Waszak, Martin R.↗
NASA NTRS1998

Online Access to Weather Satellite Imagery Through the World Wide Web

Both global area coverage (GAC) and high-resolution picture transmission (HRTP) data from the Advanced Very High Resolution Radiometer (AVHRR) are made available to laternet users through an online data access system. Older GOES-7 data am also available. Created as a "testbed" data system for NASA's future Earth Observing System Data and Information System (EOSDIS), this testbed provides an opportunity to test both the technical requirements of an onune'd;ta system and the different ways in which the -general user, community would employ such a system. Initiated in December 1991, the basic data system experienced five major evolutionary changes In response to user requests and requirements. Features added with these changes were the addition of online browse, user subsetting, dynamic image Processing/navigation, a stand-alone data storage system, and movement,from an X-windows graphical user Interface (GUI) to a World Wide Web (WWW) interface. Over Its lifetime, the system has had as many as 2500 registered users. The system on the WWW has had over 2500 hits since October 1995. Many of these hits are by casual users that only take the GIF images directly from the interface screens and do not specifically order digital data. Still, there b a consistent stream of users ordering the navigated image data and related products (maps and so forth). We have recently added a real-time, seven- day, northwestern United States normalized difference vegetation index (NDVI) composite that has generated considerable Interest. Index Terms-Data system, earth science, online access, satellite data.

Emery, W.↗
NASA NTRS1999

Martian Aerocapture Terminal Point Guidance: A Reference Path Optimization Study

An effective method of terminal point guidance is to employ influence coefficients, which are solved from a set of differential equations adjoint to the linearized perturbations of the equations of motion about a reference trajectory. Hence, to optimize this type of guidance, one must first optimize the reference trajectory that the guidance is based upon. This study concentrates on various methods to optimize a reference trajectory for a Martian aerocapture maneuver, including a parametric analysis and first order gradient method. Resulting reference trajectories were tested in separate 2000 6-DOF Monte Carlo runs, using the Atmospheric Guidance Algorithm Testbed for the Mars Surveyor Program 2001 (MSP '01) Orbiter. These results were compared to an August 1998 study using the same terminal point control guidance algorithm and simulation testbed. Satisfactory improvements over the 1998 study are amply demonstrated.

Ro, Theodore U.↗
NASA NTRS1998

Autonomous Satellite Command and Control Through the World Wide Web

The Automated Space System Experimental Testbed (ASSET) system is a simple yet comprehensive real-world operations network being developed. Phase 3 of the ASSET Project was January-December 1997 and is the subject of this report. This phase permitted SSDL and its project partners to expand the ASSET system in a variety of ways. These added capabilities included the advancement of ground station capabilities, the adaptation of spacecraft on-board software, and the expansion of capabilities of the ASSET management algorithms. Specific goals of Phase 3 were: (1) Extend Web-based goal-level commanding for both the payload PI and the spacecraft engineer. (2) Support prioritized handling of multiple (PIs) Principle Investigators as well as associated payload experimenters. (3) Expand the number and types of experiments supported by the ASSET system and its associated spacecraft. (4) Implement more advanced resource management, modeling and fault management capabilities that integrate the space and ground segments of the space system hardware. (5) Implement a beacon monitoring test. (6) Implement an experimental blackboard controller for space system management. (7) Further define typical ground station developments required for Internet-based remote control and for full system automation of the PI-to-spacecraft link. Each of those goals are examined. Significant sections of this report were also published as a conference paper. Several publications produced in support of this grant are included as attachments. Titles include: 1) Experimental Initiatives in Space System Operations; 2) The ASSET Client Interface: Balancing High Level Specification with Low Level Control; 3) Specifying Spacecraft Operations At The Product/Service Level; 4) The Design of a Highly Configurable, Reusable Operating System for Testbed Satellites; 5) Automated Health Operations For The Sapphire Spacecraft; 6) Engineering Data Summaries for Space Missions; and 7) Experiments In Automated Health Assessment And Notification For The Sapphire Microsatellite.

Cantwell, Brian↗
NASA NTRS1999

Autonomous Command Operations of the WIRE Spacecraft

This paper presents operational innovations which will be introduced on NASA's Wide Field Infrared Explorer (WIRE) mission. These innovations include an end-to-end design architecture for an autonomous commanding capability for the uplink of command loads during unattended station contacts. The WIRE mission is the fifth and final mission of NASA's Goddard Space Flight Center Small Explorer (SMEX) series to be launched in March of 1999. Its primary mission is the targeting of deep space fields using an ultra-cooled infrared telescope. Due to its mission design WIRE command loads are large (approximately 40 Kbytes per 24 hours) and must be performed daily. To reduce the cost of mission operations support that would be required in order to uplink command loads, the WIRE Flight Operations Team has implemented all autonomous command loading capability. This capability allows completely unattended operations over a typical two-day weekend period. The key factors driving design and implementation of this capability were: 1) integration with already existing ground system autonomous capabilities and systems, 2) the desire to evolve autonomous operations capabilities based upon previous SMEX operations experience - specifically the TRACE mission, 3) integration with ground station operations - both autonomous and man-tended, 4) low cost and quick implementation, and 5) end-to-end system robustness. A trade-off study was performed to examine these factors in light of the low-cost, higher-risk SMEX mission philosophy. The study concluded that a STOL (Spacecraft Test and Operations Language) based script, highly integrated with other scripts used to perform autonomous operations, was best suited given the budget and goals of the mission. Each of these factors is discussed in addition to use of the TRACE mission as a testbed for autonomous commanding prior to implementation on WIRE. The capabilities implemented on the WIRE mission are an example of a low-cost, robust, and efficient method for autonomous command loading when implemented with other autonomous features of the ground system. They call be used as a design and implementation template by other missions interested in evolving toward autonomous and lower cost operations. Additionally, the WIRE spacecraft will be used as an operational testbed upon completion of its nominal mission later in 1999. One idea being studied is advanced on-board modeling. Advanced on-board modeling techniques will be used to more efficiently display the spacecraft state. This health and safety information could be used by engineers on the ground or could be used by tile spacecraft for its own assessments. Additionally, this same state information could also be input into the event-driven scheduling system, as the scheduling system will need to assess the spacecraft state before undertaking a new activity. Advanced modeling techniques are being evaluated for a number of NASA missions including The Next Generation Space Telescope (NGST), which is scheduled to launch in 2007.

Walyus, Keith↗
NASA NTRS1999

Looking at NGST Through the Eyes of DCATT

The first phase of the Developmental Characterized Active Telescope Testbed (DCATT) hardware system was integrated at Goddard Space Flight Center in early March of 1999 and has been operational for almost a year. Experiments are currently being conducted on the testbed to quantify and refine various methods and techniques in the baseline wavefront sensing and control process. This paper addresses the actual optical design of the Phase 0 hardware configuration and discusses the open loop system level performance of the system. Lessons learned for NGST during the buildup and characterization of the system are presented.

Davila, Pam↗
NASA NTRS2000

Functionality Improvements to Overaero

The functionality of the overset, static aeroelasticity, Navier-Stokes flow solver OVERAERO was increased by adding capability to the flow solver and enhancing code performance. Improvements were made to the fluids/structure interface, an MLP version of the parallel OVERAERO code was developed, and the OVERAERO-MPI code was ported to the Cray T3E. The OVERFLOW-MPI and OVERAERO-MPI codes were tested successfully on the IPG testbed and a means of reducing communication overhead within OVERFLOW-MPI was investigated. To solve an aeroelastic problem computationally, a structures grid surface definition and a fluids grid surface definition are required. Typically, the structures grid surface has a lower fidelity than the fluids grid surface. Thus, the methods developed to transfer data between the two grid systems are vital to the accuracy and efficiency of the aeroelasticity code. The fluids/structures interface developed for the OVERAERO code was improved to more accurately treat fluids surfaces that bridge between two different structural surfaces. For example, the method allowed the forward portion of a flap track fairing to deform with the wing and the aft end of the fairing to deform with the flap. A tightly-coupled version of the code based on OVERFLOW-MLP was developed to improve code performance on the SGI Origin 2000. This required a new parallelization strategy to couple the fluids and structures codes. The OVERAERO-MPI code was ported to the Cray T3E to extend the usability of the code. The port required extensive use of dynamic memory management techniques to fit large problems within the memory limitations of the T3E. The OVERFLOW-MPI and OVERAERO-MPI codes were tested on the IPG testbed being developed within NASA. For small problems with minimal data transfer between grids, there was little to no performance penalty spreading the computation across two machines. For very large problems, methods were developed to minimize intermachine communication via the grid partitioning scheme. By minimizing the intermachine communication requirements of the problem, it may still be beneficial to run a tightly-coupled flow solver across two machines within the IPG.

Gee, Ken↗
NASA NTRS2001

Design of a High Resolution Hexapod Positioning Mechanism

This paper describes the development of a high resolution, six-degree of freedom positioning mechanism. This mechanism, based on the Stewart platform concept, was designed for use with the Developmental Comparative Active Optics Telescope Testbed (DCATT), a ground-based technology testbed for the Next Generation Space Telescope (NGST). The mechanism provides active control to the DCATT telescope's segmented primary mirror. Emphasis is on design decisions and technical challenges. Significant issues include undesirable motion properties of PZT-inchworm actuators, testing difficulties, dimensional stability and use of advanced composite materials. Supporting test data from prototype mechanisms is presented.

Britt, Jamie↗
NASA NTRS2001

Design of a High Resolution Hexapod Positioning Mechanism

This paper describes the development of a high resolution, six-degree of freedom positioning mechanism. This mechanism, based on the Stewart platform concept, was designed for use with the Developmental Comparative Active Optics Telescope Testbed (DCATT), a ground-based technology testbed for the Next Generation Space Telescope (NGST). The mechanism provides active control to the DCATT telescope's segmented primary mirror. Emphasis is on design decisions and technical challenges. Significant issues include undesirable motion properties of PZT-inchworm actuators, testing difficulties, dimensional stability, and use of advanced composite materials. Supporting test data from prototype mechanisms is presented.

Britt, Jamie↗
NASA NTRS2001

Use of Soft Computing Technologies for a Qualitative and Reliable Engine Control System for Propulsion Systems

The problem to be addressed in this paper is to explore how the use of Soft Computing Technologies (SCT) could be employed to improve overall vehicle system safety, reliability, and rocket engine performance by development of a qualitative and reliable engine control system (QRECS). Specifically, this will be addressed by enhancing rocket engine control using SCT, innovative data mining tools, and sound software engineering practices used in Marshall's Flight Software Group (FSG). The principle goals for addressing the issue of quality are to improve software management, software development time, software maintenance, processor execution, fault tolerance and mitigation, and nonlinear control in power level transitions. The intent is not to discuss any shortcomings of existing engine control methodologies, but to provide alternative design choices for control, implementation, performance, and sustaining engineering, all relative to addressing the issue of reliability. The approaches outlined in this paper will require knowledge in the fields of rocket engine propulsion (system level), software engineering for embedded flight software systems, and soft computing technologies (i.e., neural networks, fuzzy logic, data mining, and Bayesian belief networks); some of which are briefed in this paper. For this effort, the targeted demonstration rocket engine testbed is the MC-1 engine (formerly FASTRAC) which is simulated with hardware and software in the Marshall Avionics & Software Testbed (MAST) laboratory that currently resides at NASA's Marshall Space Flight Center, building 4476, and is managed by the Avionics Department. A brief plan of action for design, development, implementation, and testing a Phase One effort for QRECS is given, along with expected results. Phase One will focus on development of a Smart Start Engine Module and a Mainstage Engine Module for proper engine start and mainstage engine operations. The overall intent is to demonstrate that by employing soft computing technologies, the quality and reliability of the overall scheme to engine controller development is further improved and vehicle safety is further insured. The final product that this paper proposes is an approach to development of an alternative low cost engine controller that would be capable of performing in unique vision spacecraft vehicles requiring low cost advanced avionics architectures for autonomous operations from engine pre-start to engine shutdown.

Trevino, Luis↗
NASA NTRS1998

Integration of Biological, Physical/Chemical and Energy Efficient Systems in the CELSS Antarctic Analog: Performance of Prototype Systems and Issues for Life Support

The Controlled Ecological Life Support System (CELSS) Antarctic Analog Project (CAAP) is a joint endeavor between the National Science Foundation, Office of Polar Programs (NSF-OPP), and the National Aeronautics and Space Administration (NASA). The fundamental objective is to develop, deploy, and operate a testbed of advanced life support technologies at the Amundsen-Scott South Pole Station that enable the objectives of both the NSF and NASA. The functions of food production, water purification, and waste treatment, recycle, and reduction provided by CAAP will improve the quality of life for the South Pole inhabitants, reduce logistics dependence, enhance safety, and minimize environmental impacts associated with human presence on the polar plateau. Because of the analogous technical, scientific, and mission features with Planetary missions, such as a mission to Mars, CAAP provides NASA with a method for validating technologies and overall approaches to supporting humans. Prototype systems for waste treatment, water recycle, resource recovery and crop production are being evaluated in a testbed at Ames Research Center. The combined performance of these biological and physical/chemical systems as an integrated function in support of the human habitat will be discussed. Overall system performance will be emphasized. The effectiveness and efficiency of component technologies will be discussed in the context of energy and mass flow within the system and contribution to achieving a mass and energy conservative system. Critical to the discussion are interfaces with habitat functions outside of the closed-loop life support: the ability of the system to satisfy the life support requirements of the habitat and the ability to define input requirements. The significance of analog functions in relation to future Mars habitats will be discussed.

Bubenheim, David L.↗
NASA NTRS2002

NASA Hybrid Reflectometer Project

Time-domain and frequency-domain reflectometry have been used for about forty years to locate opens and shorts in cables. Interpretation of reflectometry data is as much art as science. Is there information in the data that is being missed? Can the reflectometers be improved to allow us to detect and locate defects in cables that are not outright shorts or opens? The Hybrid Reflectometer Project was begun this year at NASA Ames Research Center, initially to model wire physics, simulating time-domain reflectometry (TDR) signals in those models and validating the models against actual TDR data taken on testbed cables. Theoretical models of reflectometry in wires will give us an understanding of the merits and limits of these techniques and will guide the application of a proposed hybrid reflectometer with the aim of enhancing reflectometer sensitivity to the point that wire defects can be detected. We will point out efforts by some other researchers to apply wire physics models to the problem of defect detection in wires and we will describe our own initial efforts to create wire physics models and report on testbed validation of the TDR simulations.

Lynch, Dana↗
NASA NTRS2002

LWS/SET End-to-End Data System

This paper describes the concept for the End-to-End Data System that will support NASA's Living With a Star Space Environment Testbed missions. NASA has initiated the Living With a Star (LWS) Program to develop a better scientific understanding to address the aspects of the connected Sun-Earth system that affect life and society. A principal goal of the program is to bridge the gap.between science, engineering, and user application communities. The Space Environment Testbed (SET) Project is one element of LWS. The Project will enable future science, operational, and commercial objectives in space and atmospheric environments by improving engineering approaches to the accommodation and/or mitigation of the effects of solar variability on technological systems. The End-to-end data system allows investigators to access the SET control center, command their experiments, and receive data from their experiments back at their home facility, using the Internet. The logical functioning of major components of the end-to-end data system are described, including the GSFC Payload Operations Control Center (POCC), SET Payloads, the GSFC SET Simulation Lab, SET Experiment PI Facilities, and Host Systems. Host Spacecraft Operations Control Centers (SOCC) and the Host Spacecraft are essential links in the end-to-end data system, but are not directly under the control of the SET Project. Formal interfaces will be established between these entities and elements of the SET Project. The paper describes data flow through the system, from PI facilities connecting to the SET operations center via the Internet, communications to SET carriers and experiments via host systems, to telemetry returns to investigators from their flight experiments. It also outlines the techniques that will be used to meet mission requirements, while holding development and operational costs to a minimum. Additional information is included in the original extended abstract.

Giffin, Geoff↗
NASA NTRS2003

Experimental Results From a 2kW Brayton Power Conversion Unit

This paper presents experimental test results from operation of a 2 kWe Brayton power conversion unit. The Brayton converter was developed for a solar dynamic power system flight experiment planned for the Mir Space Station in 1997. The flight experiment was cancelled, but the converter was tested at Glenn Research Center as part of the Solar Dynamic Ground Test Demonstration system which included a solar concentrator, heat receiver, and space radiator. In preparation for the current testing, the heat receiver was removed and replaced with an electrical resistance heater, simulating the thermal input of a steady-state nuclear source. The converter was operated over a full range of thermal input power levels and rotor speeds to generate an overall performance map. The converter unit will serve as the centerpiece of a Nuclear Electric Propulsion Testbed at Glenn. Future potential uses for the Testbed include high voltage electrical controller development, integrated electric thruster testing and advanced radiator demonstration testing to help guide high power Brayton technology development for Nuclear Electric Propulsion (NEP).

Hervol, David↗