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At least 883 records · Page 49

MEMS Louvers for Thermal Control

Mechanical louvers have frequently been used for spacecraft and instrument thermal control purposes. These devices typically consist of parallel or radial vanes, which can be opened or closed to vary the effective emissivity of the underlying surface. This project demonstrates the feasibility of using Micro-Electromechanical Systems (MEMS) technology to miniaturize louvers for such purposes. This concept offers the possibility of substituting the smaller, lighter weight, more rugged, and less costly MEMS devices for such mechanical louvers. In effect, a smart skin that self adjusts in response to environmental influences could be developed composed of arrays of thousands of miniaturized louvers. Several orders of magnitude size, weight, and volume decreases are potentially achieved using micro-electromechanical techniques. The use of this technology offers substantial benefits in spacecraft/instrument design, integration and testing, and flight operations. It will be particularly beneficial for the emerging smaller spacecraft and instruments of the future. In addition, this MEMS thermal louver technology can form the basis for related spacecraft instrument applications. The specific goal of this effort was to develop a preliminary MEMS device capable of modulating the effective emissivity of radiators on spacecraft. The concept pursued uses hinged panels, or louvers, in a manner such that heat emitted from the radiators is a function of louver angle. An electrostatic comb drive or other such actuator can control the louver position. The initial design calls for the louvers to be gold coated while the underlying surface is of high emissivity. Since, the base MEMS material, silicon, is transparent in the InfraRed (IR) spectrum, the device has a minimum emissivity when closed and a maximum emissivity when open. An initial set of polysilicon louver devices was designed at the Johns Hopkins Applied Physics Laboratory in conjunction with the Thermal Engineering Branch at NASA's Goddard Space Flight Center.

Champion, J. L.↗

Superwinds in Seyfert Galaxies SFGs and AGN

This project was successfully completed; three refereed publications have been published on the work and the graduate student involved successfully defended his thesis. The work done in conjunction with this project demonstrated for the first time the importance of large scale winds in most if not all Seyfert galaxies and explored the physical parameters of those winds and their effect on both the interstellar medium of the host galaxy and the activity in the active nucleus as well.

Baum, Stefi↗

Advanced Engineering Environments for Space Transportation System Development

There are significant challenges facing today's launch vehicle industry. Global competition, more complex products, geographically-distributed design teams, demands for lower cost, higher reliability and safer vehicles, and the need to incorporate the latest technologies quicker, all face the developer of a space transportation system. Within NASA, multiple technology development and demonstration projects are underway toward the objectives of safe, reliable, and affordable access to space. New information technologies offer promising opportunities to develop advanced engineering environments to meet these challenges. Significant advances in the state-of-the-art of aerospace engineering practice are envisioned in the areas of engineering design and analytical tools, cost and risk tools, collaborative engineering, and high-fidelity simulations early in the development cycle. At the Marshall Space Flight Center, work has begun on development of an advanced engineering environment specifically to support the design, modeling, and analysis of space transportation systems. This paper will give an overview of the challenges of developing space transportation systems in today's environment and subsequently discuss the advanced engineering environment and its anticipated benefits.

Thomas, L. Dale↗

Joint NASA/EPA AVIRIS Analysis in the Chesapeake Bay Region: Plans and Initial Results

NASA's Ames Research Center is performing an AVIRIS demonstration project in conjunction with the U. S. Environmental Protection Agency (Region 3). NASA and EPA scientists have jointly defined a Study Area in eastern Virginia to include portions of the Chesapeake Bay, southern Delmarva Peninsula, and the mouths of the York and James Rivers. Several environmental issues have been identified for study. These include, by priority: 1) water constituent analysis in the Chesapeake Bay, 2) mapping of submerged aquatic vegetation in the Bay, 3) detection of vegetation stress related to Superfund sites at the Yorktown Naval Weapons Station, and 4) wetland species analysis in the York River vicinity. In support of this project, three lines of AVIRIS data were collected during the Wallops Island deployment on 17 August 1997. The remote sensing payload included AVIRIS, MODIS Airborne Simulator and an RC-10 color infrared film camera. The AVIRIS data were delivered to Ames from the JPL AVIRIS Data Facility, on 29 September 1997. Quicklook images indicate nominal data acquisition, and at the current time an atmospheric correction is being applied. Water constituent analysis of the Bay is our highest priority based on EPA interest and available collateral data, both from the surface and from other remote sensing instruments. Constituents of interest include suspended sediments, chlorophyll-a and accessory pigments, Analysis steps will include: verification of data quality, location of study sites in imagery, incorporation of relevant field data from EPA and other Chesapeake Bay cooperators, processing of imagery to show phenomenon of interest, verification of results with cooperators. By 1st quarter CY98 we plan to circulate initial results to NASA and EPA management for review. In the longer term we will finalize documentation, prepare results for publication, and complete any needed technology transfer to EPA remote sensing personnel.

Johnson, Lee↗

Free Space Laser Communications

This presentation concerns the use of Laser communication for deep space applications. The presentation reviews the problems with electromagnetic beams and then the advantages and disadvantages of the use of optical communication. The presentation then reviews some of the spacecraft technology with pictures of some of the devices. The ground reception systems and the simplified link calculation are also reviewed. Recent and planned demonstration projects are also reviewed.

Lesh, James↗

Simulation of a Flywheel Electrical System for Aerospace Applications

A Flywheel Energy Storage Demonstration Project was initiated at the NASA Glenn Research Center as a possible replacement for the battery energy storage system on the International Space Station (ISS). While the hardware fabrication work was being performed at a university and contractor's facility, the related simulation activity was begun at Glenn. At the top level, Glenn researchers simulated the operation of the ISS primary electrical system (as described in another paper) with the Flywheel Energy Storage Unit (FESU) replacing one Battery Charge and Discharge Unit (BCDU). The FESU consists of a Permanent Magnet Synchronous Motor/Generator (PMSM), which is connected to the flywheel; the power electronics that connects the PMSM to the ISS direct-current bus; and the associated controller. The PMSM model is still under development, but this paper describes the rest of the FESU model-the simulation of the converter and the associated control system that regulates energy transfer to and from the flywheel.

Truong, Long V.↗

Selection of the Ground Segment for the Next Generation Space Telescope (NGST) Flight Demonstrator (Nexus)

Nexus was a technology demonstrator project that was designed to bridge from the Hubble Space Telescope (HST) to its successor, the Next Generation Space Telescope (NGST). This paper focuses on the process used in designing the ground segment for Nexus and the lessons learned in its development. Ground station cost drivers were: (1) Contact time, (2) Cost of transporting data between the ground stations and control center, and (3) Cost savings via ground automation. We found that reducing the communication requirement in just the first 100 days could have reduced the total ground station cost by 40%. Contact time cost dwarfed the cost trade between automation development and off-shift operations personnel. Real-time Telemetry and Control (T&C) system analysis was divided into: (1) Potential reuse of the Nexus real-time (T&C) system for NGST, (2) Feasibility of using a 'Finite State-Based Modeling' product, and (3) Selecting a Commercial Off the Shelf (COTS) versus Government Off The Shelf (GOTS) products. We found that each of the products evaluated in detail (ASIST, EPOCH 2000, and ITOS) could adequately support basic mission requirements. Lessons learned were: (1) Include operations at the beginning of the mission, and (2) Develop an operations concept as soon as possible.

Gal-Edd, Jonathan↗

Retractable Trunnion Pin Mechanism

The X-38 is a technology demonstration project for the proposed International Space Station Crew Return Vehicle. The project consists of several atmospheric flight vehicles and an unmanned spacecraft. This paper will discuss the design, development, and testing of a Retractable Trunnion Pin Mechanism used to mount the spacecraft in the payload bay of the space shuttle orbiter for launch.

Jermstad, Wayne↗

Continuous Remote Measurements of Atmospheric O2 Concentrations in Relation to Interannual Variations in Biological Production and Carbon Cycling in the Oceans

We successfully initiated a program to obtain continuous time series of atmospheric O2 concentrations at a semi-remote coastal site, in Trinidad, California. The installation, which was completed in September 1999, consists of a commercially-available O2 and CO2 analyzers interfaced to a custom gas handling system and housed in a dedicated building at the Trinidad site. Ultimately, the data from this site are expected to provide constraints, complementing satellite data, on variations in ocean productivity and carbon exchange on annual and interannual time scales, in the context of human-induced changes in global climate and other perturbations. The existing time-series, of limited duration, have been used in support of studies of the O2/CO2 exchange from a wild fire (which fortuitously occurred nearby in October 1999) and to quantify air-sea N2O and O2 exchanges related to coastal upwelling events. More generally, the project demonstrates the feasibility of obtaining semi-continuous O2 time series at moderate cost from strategic locations globally.

Keeling, Ralph F.↗

Design and Test of an Improved Crashworthiness Small Composite Airframe

The purpose of this small business innovative research (SBIR) program was to evaluate the feasibility of developing small composite airplanes with improved crashworthiness. A combination of analysis and half scale component tests were used to develop an energy absorbing airframe. Four full scale crash tests were conducted at the NASA Impact Dynamics Research Facility, two on a hard surface and two onto soft soil, replicating earlier NASA tests of production general aviation airplanes. Several seat designs and restraint systems including both an air bag and load limiting shoulder harnesses were tested. Tests showed that occupant loads were within survivable limits with the improved structural design and the proper combination of seats and restraint systems. There was no loss of cabin volume during the events. The analysis method developed provided design guidance but time did not allow extending the analysis to soft soil impact. This project demonstrated that survivability improvements are possible with modest weight penalties. The design methods can be readily applied by airplane designers using the examples in this report.

Terry, James E.↗

Flight Demonstrations of Orbital Space Plane (OSP) Technologies

The Orbital Space Plane (OSP) Program embodies NASA s priority to transport Space Station crews safely, reliably, and affordably, while it empowers the Nation s greater strategies for scientific exploration and space leadership. As early in the development cycle as possible, the OSP will provide crew rescue capability, offering an emergency ride home from the Space Station, while accommodating astronauts who are deconditioned due to long- duration missions, or those that may be ill or injured. As the OSP Program develops a fully integrated system, it will use existing technologies and employ computer modeling and simulation. Select flight demonstrator projects will provide valuable data on launch, orbital, reentry, and landing conditions to validate thermal protection systems, autonomous operations, and other advancements, especially those related to crew safety and survival.

Turner, Susan↗

The Chemistry of Early Self-Replicating Systems

The NASA Specialized Center of Research and Training in Exobiology (NSCORT/Exobiology) is a program within the UCSD California Space Institute (Dr. Wolfgang Berger, Director) currently funded by a second 5 year Federal Demonstration Project Grant from NASA. Its specific aims are: 1. The support and training of Postdoctoral, Graduate, and Undergraduate Fellows in Exobiology. 2. The support of research by the Principal Investigators and Fellows in the field of Exobiology. 3. Outreach programs emphasizing the dissemination and exchange of information concerning Exobiology within the scientific community, primary, secondary and college students, and the general public. 4. Host of the 1999 meeting of the International Society for the Study of the Origin of Life (ISSOL) held at the University of California, San Diego in La Jolla, California, from Sunday, July 11 through Friday, July 16,1999.

Bada, Jeffrey L.↗

Achievements of the DOT-NASA Joint Program on Remote Sensing and Spatial Information Technologies: Application to Multimodal Transportation

This report presents three-year accomplishments from the national program on Commercial Remote Sensing and Geospatial Technology (CRSGT) application to transportation, administered by the U.S. Department of Transportation (U.S. DOT) in collaboration with the National Aeronautics and Space Administration (NASA). The joint program was authorized under Section 5113 of the Transportation Equity Act for the 21st Century (TEA-21). This is the first national program of its type focusing on transportation applications of emerging commercial remote sensing technologies. U.S. DOT's Research and Special Programs Administration manages the program in coordination with NASA's Earth Science Enterprise's application programs. The program focuses on applications of CRSGT products and systems for providing smarter and more efficient transportation operations and services. The program is performed in partnership with four major National Consortia for Remote Sensing in Transportation (NCRST). Each consortium focuses on research and development of products in one of the four priority areas for transportation application, and includes technical application and demonstration projects carried out in partnership with industries and service providers in their respective areas. The report identifies products and accomplishments from each of the four consortia in meeting the goal of providing smarter and more efficient transportation services. The products and results emerging from the program are being implemented in transportation operations and services through state and local agencies. The Environmental Assessment and Application Consortium (NCRST-E) provides leadership for developing and deploying cost effective environmental and transportation planning services, and integrates CRSGT advances for achieving smarter and cost effective corridor planning. The Infrastructure Management Consortium (NCRST-I) provides leadership in technologies that achieve smarter and cheaper ways of managing transportation infrastructure assets, operation, and inspection, and integrates CRSGT advances for achieving infrastructure security. The Traffic Flow Consortium (NCRST-F) provides leadership to develop new tools for regional traffic flow management including heavy vehicles and intermodal flow of freight, and integrates CRSGT advances for complementing and extending the reach of ITS user services. The Safety, Hazards and Disasters (NCRST-H) provides leadership for deploying remote sensing technology to locate transportation hazards and improve disaster recovery, and integrates CRSGT advances for application to protect transportation systems from terrorism. The DOT-NASA team is proud to present this report of accomplishments on products and results emerging from the joint program for application to transportation practice.

Source record↗

A Sensitivity Study of the Aircraft Vortex Spacing System (AVOSS) Wake Predictor Algorithm to the Resolution of Input Meteorological Profiles

The AVOSS project demonstrated the feasibility of applying aircraft wake vortex sensing and prediction technologies to safe aircraft spacing for single runway arrivals. On average, AVOSS provided spacing recommendations that were less than the current FAA prescribed spacing rules, resulting in a potential airport efficiency gain. Subsequent efforts have included quantifying the operational specifications for future Wake Vortex Advisory Systems (WakeVAS). In support of these efforts, each of the candidate subsystems for a WakeVAS must be specified. The specifications represent a consensus between the high-level requirements and the capabilities of the candidate technologies. This report documents the beginnings of an effort to quantify the capabilities of the AVOSS Prediction Algorithm (APA). Specifically, the APA horizontal position and circulation strength output sensitivity to the resolution of its wind and turbulence inputs is examined. The results of this analysis have implications for the requirements of the meteorological sensing and prediction systems comprising a WakeVAS implementation.

Rutishauser, David K.↗

NASA Scientific Data Purchase

The paper discusses the folloving: 1. 50 Million ,Appropriation - Acquire science data from commercial sources. 2. Demonstration Project - Test new way of doing business. Tap new sources of data. Support Earth science research. Support commercial remote sensing industry. 3. Phase I - Review simulated/prototypical datasets (10 companies). 4. Phase II - 3-year purchase/distribution of select data (5 companies). 5. FY01 $20M Appropriation - Commercial Imagery Office Proposed continuation and new contracts.

Davis, Bruce↗

NASA Langley Research and Technology-Transfer Program in Formal Methods

This paper presents an overview of NASA Langley research program in formal methods. The major goals of this work are to make formal methods practical for use on life critical systems, and to orchestrate the transfer of this technology to U.S. industry through use of carefully designed demonstration projects. Several direct technology transfer efforts have been initiated that apply formal methods to critical subsystems of real aerospace computer systems. The research team consists of five NASA civil servants and contractors from Odyssey Research Associates, SRI International, and VIGYAN Inc.

Butler, Ricky W.↗

Infrared Avionics Signal Distribution Using WDM

Supporting analog RF signal transmission over optical fibers, this project demonstrates a successful application of wavelength division multiplexing (WDM) to the avionics environment. We characterize the simultaneous transmission of four RF signals (channels) over a single optical fiber. At different points along a fiber optic backbone, these four analog channels are sequentially multiplexed and demultiplexed to more closely emulate the conditions in existing onboard aircraft. We present data from measurements of optical power, transmission response (loss and gain), reflection response, group delay that defines phase distortion, signal-to-noise ratio (SNR), and dynamic range that defines nonlinear distortion. The data indicate that WDM is very suitable for avionics applications.

Atiquzzaman, Mohammed↗

Feasibility Assessment for Pressure Casting of Ceramic-Aluminum Composites for NASA's Propulsion Applications

Feasibility assessment of pressure casting of ceramic-aluminum composites for NASA% propulsion applications is summarized. A combination of several demonstration projects to produce three unique components for liquid hydrogen-oxygen rocket engine% flanges, valves and turbo-pump housing are conducted. These components are made from boron carbide, silicon carbide and alumina powders fabricated into complex net shaped parts using dry green powder compaction, slip casting or a novel 3D ink-jet printing process, followed by sintering to produce performs that can be pressure cast by infiltration with molten aluminum. I n addition, joining techniques are also explored to insure that these components can be assembled into a structure without degrading their highly tailored properties. The feasibility assessment was made to determine if these new materials could provide a significant weight savings, thereby reducing vehicle launch costs, while being durable materials to increase safety and performance for propulsion system.

Lee, Jonathan A.↗