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At least 667 records · Page 37

Concurrent engineering research center

The projects undertaken by The Concurrent Engineering Research Center (CERC) at West Virginia University are reported and summarized. CERC's participation in the Department of Defense's Defense Advanced Research Project relating to technology needed to improve the product development process is described, particularly in the area of advanced weapon systems. The efforts committed to improving collaboration among the diverse and distributed health care providers are reported, along with the research activities for NASA in Independent Software Verification and Validation. CERC also takes part in the electronic respirator certification initiated by The National Institute for Occupational Safety and Health, as well as in the efforts to find a solution to the problem of producing environment-friendly end-products for product developers worldwide. The 3M Fiber Metal Matrix Composite Model Factory Program is discussed. CERC technologies, facilities,and personnel-related issues are described, along with its library and technical services and recent publications.

Callahan, John R.↗

Alloy-Enhanced Fans Maintain Fresh Air in Tunnels

The Partnership for Next Generation Vehicles (PNGV) is not a NASA initiative to develop powerful new rockets and spacecraft, even though it may sound like one. PNGV was a partnership established by the Clinton administration between the Federal government and the U.S. Council for Automotive Research to develop technologies that improve fuel efficiency and reduce emissions from cars and trucks. More than 20 Federal laboratories from the Departments of Commerce, Energy, Transportation, and Defense; the Environmental Protection Agency; the National Science Foundation; and NASA were all involved in PNGV, in addition to more than 350 automotive suppliers, universities, and small businesses. In support of this tremendous effort, Jonathan Lee, a materials engineer at Marshall Space Flight Center, worked with a major automobile manufacturer in 1995 to develop a strong aluminum alloy for high temperature applications. The aim was to use the alloy for manufacturing parts for an internal combustion engine, as well as for NASA s propulsion applications. When funding from PNGV ended, Marshall continued to support the alloy s development with help from NASA s Innovative Partnerships Program (now the Office of the Chief Technologist). Together with PoShou Chen, a scientist with Morgan Research Corporation, Lee invented a highstrength aluminum alloy called MSFC-398 that, when tested, was three to four times stronger than conventional aluminum alloys at high temperatures. By the late 1990s, Lee says, NASA s scientists had successfully developed and patented this technology, which has great potential applications not for just automotive, but also for aerospace, marine, and commercial applications

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Weather Prediction Improvement Using Advanced Satellite Technology

We discuss in this paper some of the problems that exist today in the fall utilization of satellite data to improve weather forecasts and we propose specific recommendations to solve them. This discussion can be viewed as an aspect of the general debate on how best to organize the transition from research to operational satellites and how to evaluate the impact of a research instrument on numerical weather predictions. A method for providing this transition is offered by the National Polar-Orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP). This mission will bridge the time between the present NOAA and Department of Defense (DOD) polar orbiting missions and the initiation of the converged NPOESS series and will evaluate some of the Earth Observing System (EOS) instruments as appropriate for operational missions. Thus, this mission can be viewed as an effort to meet the operational requirements of NOAA and DOD and the research requirements of NASA. More generally, however, it can be said that the process of going from the conception of new, more advanced instruments to their operational implementation and full utilization by the weather forecast communities is not optimal. Instruments developed for research purposes may have insufficient funding to explore their potential operational capabilities. Furthermore, instrument development programs designed for operational satellites typically have insufficient funding for assimilation algorithms needed to transform the satellite observations into data that can be used by sophisticated global weather forecast models. As a result, years often go by before satellite data are efficiently used for operational forecasts. NASA and NOAA each have unique expertise in the design of satellite instruments, their use for basic and applied research and their utilization in weather and climate research. At a time of limited resources, the two agencies must combine their efforts to work toward common goals of full utilization of satellite data. This is a challenge that requires the assimilation of myriad new data into increasingly sophisticated numerical forecast models that run on increasingly sophisticated computer systems. In section II, we briefly outline the impact of satellite data on the quality of the National Centers for Environmental Prediction (NCEP) forecasts. In section III, we describe the present status of the utilization of satellite data in NCEP models and the challenges that lie ahead. In section IV, we propose solutions whose goals are summarized in section V.

Einaudi, Franco↗

Final Environmental Impact Statement for the Galileo Mission (Tier 2)

This Final Environmental Impact Statement (FEIS) addresses the proposed action of completing the preparation and operation of the Galileo spacecraft, including its planned launch on the Space Transportation System (STS) Shuttle in October 1989, and the alternative of canceling further work on the mission. The Tier 1 (program level) EIS (NASA 1988a) considered the Titan IV launch vehicle as an alternative booster stage for launch in May 1991 or later. The May 1991 Venus launch opportunity is considered a planetary back-up for the Magellan (Venus Radar Mapper) mission, the Galileo mission, and the Ulysses mission. Plans were underway to enable the use of a Titan IV launch vehicle for the planetary back-up. However, in November 1988, the U.S. Air Force, which procures the Titan IV for NASA, notified NASA that it could not provide a Titan IV vehicle for the May 1991 launch opportunity due to high priority Department of Defense requirements. Consequently, NASA terminated all mission planning for the Titan IV planetary back-up. A minimum of 3 years is required to implement mission-specific modifications to the basic Titan IV launch configuration; therefore, insufficient time is available to use a Titan IV vehicle in May 1991. Thus, the Titan IV launch vehicle is no longer a feasible alternative to the STS/Inertial Upper Stage (IUS) for the May 1991 launch opportunity.

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Test Capabilities of the NASA Langley Direct Connect Supersonic Combustion Test Facility

In 1969 a combustion-heated direct-connect test facility was assembled at the NASA Langley Research Center and used to support NASA’s Hypersonic Research Engine program. Later, the facility was used to support NASA’s generic hypersonic program, assessing the mixing, ignition, flame holding, and combustion characteristics of ramjet and scramjet combustors. Over the years, the facility has been updated and modified to conduct increasingly complicated tests. Today, the facility is known as the Direct Connect Supersonic Combustion Test Facility (DCSCTF) and is part of the NASA Langley Scramjet Test Complex. Recently, the facility has been used by external customers to test fuel-cooled and uncooled, flight-like test articles. Tests have been conducted at nominal Mach 5 flight conditions for up to 15 minutes of continuous operation. The facility remains a viable and useful tool in the support of various Department of Defense projects.

Diego P Capriotti↗

Low Cost Large Core Vehicle Structures Assessment

Boeing Information, Space, and Defense Systems executed a Low Cost Large Core Vehicle Structures Assessment (LCLCVSA) under contract to NASA Marshall Space Flight Center (MSFC) between November 1997 and March 1998. NASA is interested in a low-cost launch vehicle, code named Magnum, to place heavy payloads into low earth orbit for missions such as a manned mission to Mars, a Next Generation Space Telescope, a lunar-based telescope, the Air Force's proposed space based laser, and large commercial satellites. In this study, structural concepts with the potential to reduce fabrication costs were evaluated in application to the Magnum Launch Vehicle (MLV) and the Liquid Fly Back Booster (LFBB) shuttle upgrade program. Seventeen concepts were qualitatively evaluated to select four concepts for more in-depth study. The four structural concepts selected were: an aluminum-lithium monocoque structure, an aluminum-lithium machined isogrid structure, a unitized composite sandwich structure, and a unitized composite grid structure. These were compared against a baseline concept based on the Space Shuttle External Tank (ET) construction. It was found that unitized composite structures offer significant cost and weight benefits to MLV structures. The limited study of application to LFBB structures indicated lower, but still significant benefits. Technology and facilities development roadmaps to prepare the approaches studied for application to MLV and LFBB were constructed. It was found that the cost and schedule to develop these approaches were in line with both MLV and LFBB development schedules. Current Government and Boeing programs which address elements of the development of the technologies identified are underway. It is recommended that NASA devote resources in a timely fashion to address the specific elements related to MLV and LFBB structures.

Hahn, Steven E.↗

HRP Chief Scientist's Office: Conducting Research to Enable Deep Space Exploration

The HRP Chief Scientist's Office sets the scientific agenda for the Human Research Program. As NASA plans for deep space exploration, HRP is conducting research to ensure the health of astronauts, and optimize human performance during extended duration missions. To accomplish this research, HRP solicits for proposals within the U.S., collaborates with agencies both domestically and abroad, and makes optimal use of ISS resources in support of human research. This session will expand on these topics and provide an opportunity for questions and discussion with the HRP Chief Scientist. Presentations in this session will include: NRA solicitations - process improvements and focus for future solicitations, Multilateral Human Research Panel for Exploration - future directions (MHRPE 2.0), Extramural liaisons - National Science Foundation (NSF) and Department of Defense (DOD), Standardized Measures for spaceflight, Ground-based Analogs - international collaborations, and International data sharing.

Charles, J. B.↗

NSI customer service representatives and user support office: NASA Science Internet

The NASA Science Internet, (NSI) was established in 1987 to provide NASA's Offices of Space Science and Applications (OSSA) missions with transparent wide-area data connectivity to NASA's researchers, computational resources, and databases. The NSI Office at NASA/Ames Research Center has the lead responsibility for implementing a total, open networking program to serve the OSSA community. NSI is a full-service communications provider whose services include science network planning, network engineering, applications development, network operations, and network information center/user support services. NSI's mission is to provide reliable high-speed communications to the NASA science community. To this end, the NSI Office manages and operates the NASA Science Internet, a multiprotocol network currently supporting both DECnet and TCP/IP protocols. NSI utilizes state-of-the-art network technology to meet its customers' requirements. THe NASA Science Internet interconnects with other national networks including the National Science Foundation's NSFNET, the Department of Energy's ESnet, and the Department of Defense's MILNET. NSI also has international connections to Japan, Australia, New Zealand, Chile, and several European countries. NSI cooperates with other government agencies as well as academic and commercial organizations to implement networking technologies which foster interoperability, improve reliability and performance, increase security and control, and expedite migration to the OSI protocols.

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Stability of large DC power systems using switching converters, with application to the international space station

As space direct current (dc) power systems continue to grow in size, switching power converters are playing an ever larger role in power conditioning and control. When designing a large dc system using power converters of this type, special attention must be placed on the electrical stability of the system and of the individual loads on the system. In the design of the electric power system (EPS) of the International Space Station (ISS), the National Aeronautics and Space Administration (NASA) and its contractor team led by Boeing Defense & Space Group has placed a great deal of emphasis on designing for system and load stability. To achieve this goal, the team has expended considerable effort deriving a dear concept on defining system stability in both a general sense and specifically with respect to the space station. The ISS power system presents numerous challenges with respect to system stability, such as high power, complex sources and undefined loads. To complicate these issues, source and load components have been designed in parallel by three major subcontractors (Boeing, Rocketdyne, and McDonnell Douglas) with interfaces to both sources and loads being designed in different countries (Russia, Japan, Canada, Europe, etc.). These issues, coupled with the program goal of limiting costs, have proven a significant challenge to the program. As a result, the program has derived an impedance specification approach for system stability. This approach is based on the significant relationship between source and load impedances and the effect of this relationship on system stability. This approach is limited in its applicability by the theoretical and practical limits on component designs as presented by each system segment. As a result, the overall approach to system stability implemented by the ISS program consists of specific hardware requirements coupled with extensive system analysis and hardware testing. Following this approach, the ISS program plans to begin construction of the world's largest orbiting power system in 1997.

Manners, B.↗

Human Factors Research for Space Exploration: Measurement, Modeling, and Mitigation

As part of NASA's Human Research Program, the Space Human Factors Engineering Project serves as the bridge between Human Factors research and Human Spaceflight applications. Our goal is to be responsive to the operational community while addressing issues at a sufficient level of abstraction to ensure that our tools and solutions generalize beyond the point design. In this panel, representatives from four of our research domains will discuss the challenges they face in solving current problems while also enabling future capabilities. Historically, engineering-dominated organizations have tended to view good Human Factors (HF) as a desire rather than a requirement in system design and development. Our field has made significant gains in the past decade, however; the Department of Defense, for example, now recognizes Human-System Integration (HSI), of which HF is a component, as an integral part of their divisions hardware acquisition processes. And our own agency was far more accepting of HF/HSI requirements during the most recent vehicle systems definition than in any prior cycle. Nonetheless, HF subject matter experts at NASA often find themselves in catch up mode... coping with legacy systems (hardware and software) and procedures that were designed with little regard for the human element, and too often with an attitude of we can deal with any operator issues during training. Our challenge, then, is to segregate the true knowledge gaps in Space Human Factors from the prior failures to incorporate best (or even good) HF design principles. Further, we strive to extract the overarching core HF issues from the point-design-specific concerns that capture the operators (and managers) attention. Generally, our approach embraces a 3M approach to Human Factors: Measurement, Modeling, and Mitigation. Our first step is to measure human performance, to move from subjective anecdotes to objective, quantified data. Next we model the phenomenon, using appropriate methods in our field, modifying them to suit the unique aspects of the space environment. Finally, we develop technologies, tools, and procedures to mitigate the decrements in human performance and capabilities that occur in space environments. When successful, we decrease risks to crew safety and to mission success. When extremely successful (or lucky), we devise generalizable solutions that advance the state of our practice. Our panel is composed of researchers from diverse domains of our project... from different boxes, if you will, of the Human Factors Analysis and Classification System (HFACS).

Kaiser, Mary K.↗

Extreme-Temperature Carbon- and Ceramic-Matrix Composite Nozzle Extensions for Liquid Rocket Engines

The United States (US) National Aeronautics and Space Administration (NASA) and its US industry partners are developing extreme-temperature composite nozzle extensions for a variety of cryogenic liquid rocket engine propulsion systems. Applications under consideration at the NASA Marshall Space Flight Center (MSFC) include launch vehicle (upper stage), in-space, and lunar lander descent/ascent propulsion systems. Composite material systems of interest include carbon-carbon (C-C) and carbon/silicon-carbide (C-SiC) composites, as well as modified versions of such composites (coatings, mixed matrices, oxidation inhibitors, etc.). Missions addressed include access to low Earth orbit, the lunar surface, and more distant destinations. Cryogenic upper-stage and in-space liquid rocket engines are optimized for performance through the use of high area ratio nozzles to fully expand combustion gases to low exit pressures, increasing exhaust velocities. As a result of the large size of such nozzles, and the related engine performance requirements, composite nozzle extensions are being considered to reduce mass impacts. Currently, metallic and foreign composite nozzle extensions used on the Atlas V, Delta IV, Falcon 9, and Ariane 5 launch vehicles represent the state-of-the-art. Such extensions are limited to use at or slightly above 2000°F (1093°C). Materials under development by MSFC and its industry partners have the potential to operate at temperatures up to (or above) 4250°F (2343°C). Marshall Space Flight Center efforts are aimed at (a) further developing the technology and databases needed to enable the use of composite nozzle extensions on cryogenic liquid rocket engines, (b) developing and demonstrating low-cost capabilities for testing and qualifying such nozzle extensions, and (c) advancing the US domestic supply chain for nozzle extensions. Through the Small Business Innovation Research (SBIR) and Small Business Technology Transfer (STTR) Programs, low-level internal MSFC research projects, and teaming arrangements with domestic industry partners, composite material design, development, hot-fire test, and evaluation efforts are progressing. Hot- fire engine tests of subscale hardware have been conducted using oxygen/hydrogen (LOX/H2), oxygen/methane (LOX/CH4), and oxygen/kerosene (LOX/RP-1) propellants. These engine tests at MSFC have enabled the evaluation of both heritage and state-of-the-art material systems, demonstrating the initial capabilities of the extreme temperature materials and their fabrication methods. Recent, ongoing, and potential future work supporting cryogenic propulsion systems development will be presented. The composite nozzle extension technology and test capabilities being developed are intended to support both NASA and US Department of Defense requirements, as well as those of the broader Commercial Space industry.

Valentine, Peter G.↗

Six mechanisms used on the SSM/1 radiometer

Future USAF Block 5D Defense Meteorological Satellites will carry a scanning microwave radiometer sensor (SSM/1). SSM/1 senses the emission of microwave energy and returns to earth data used to determine weather conditions, such as rainfall rates, soil moisture, and oceanic wind speed. The overall design of the SSM/1 radiometer was largely influenced by the mechanisms. The radiometer was designed to be stowed in a cavity on the existing spacecraft. The deployment of the sensor is complex due to the constraint of this cavity and the need for precision in the deployment. The radiometer will continuously rotate, instead of oscillate, creating the need for a bearing and power transfer assembly and a momentum compensation device. The six mechanisms developed for this program are described.

Ludwig, H. R.↗

Application of Analytical Hierarchy Process for Narrowing Down Nep Candidate Reactor Designs

Nuclear electric propulsion (NEP)-powered vehicles have been contemplated for human Mars missions. The nuclear power system contemplates using a high temperature light-weight nuclear reactor for the production of electrical power in the range of 2-5 MWe with a 3-10 year service life. A myriad of technology options exist for achieving these mission objectives. The analytic hierarchy process (AHP), a multi-attribute decision method, is being used to narrow down the candidate designs. The AHP is a structured decision process that fuses model-supplied quantitative data with subjective assessments to facilitate decisions that involve multiple competing criteria. Proven end-to-end nuclear design and systems analysis tools will be used to provide quantitative performance data such as end-to-end system reliability, system robustness to recover from off-normal conditions, system specific weight (α in kg/kWe), and the ability to meet the service life-time and power level requirements. Three high assay low enriched uranium (HALEU) reactor concepts, namely, gas-, heat pipe- and pumped liquid-cooled nuclear cores coupled to a He/Xe gas or supercritical CO2- Brayton power conversion system are being modeled using the AHP to understand the trade-offs associated with these design combinations. In addition to the reactor and power conversion options, there are a myriad of additional components and subsystems – e.g., radiators, heat exchangers, and recuperators – that also figure into the evaluation process. The choice of the right overall system is a multidimensional problem that has to include not only quantitative data, but also the so called “external factors”, examples of which include the component and subsystem Technology Readiness Levels (TRLs), the associated Advancement Degrees of Difficulty (AD2), the cost and schedule required to achieve a technical maturity consistent with mission infusion, alignment with the priorities of NASA’s Space Nuclear Propulsion program, and alignment with other ongoing government and commercial investments in micro reactors. Focused expert elicitations form the basis for qualitative data set. As a final step, decision-makers individually express their opinions regarding the relative importance of the criteria and preferences among the alternatives through pairwise comparisons. The paper will describe the AHP approach, progress to-date applying it to the NEP human Mars mission problem, and preliminary results. Use of AHP provides sufficient flexibility for incorporating industry input at different stages as the technologies evolve through additional research and development. It is expected that the decision process will be ongoing and expanded to examine additional options and technology choices, culminating in a defensible set of candidate reactor concepts that will form the basis for developing a multi-year NEP technology maturation strategy. .

Dasari V Rao↗

Fire Station #1 Area, SWMU 116 Per- and Polyfluoroalkyl Substances (PFAS) Site Assessment Progress Report Kennedy Space Center, Florida

This Per- and Polyfluoroalkyl Substances (PFAS) Site Assessment (SA) Progress Report (SAPR) discusses the investigation activities and findings for the Fire Station #1 (FS1) Area (formerly known as Fire Station #4) located at Kennedy Space Center (KSC), Florida (Figure 1-1). This site has been designated Solid Waste Management Unit (SWMU) 116 under KSC’s Resource Conservation and Recovery Act (RCRA) Corrective Action Program. This PFAS SA is being managed under SWMU 116 as the fire station was identified as a potential source of PFAS to the environment. This PFAS SAPR was prepared by Tetra Tech, Inc., for the National Aeronautics and Space Administration (NASA) under Indefinite Delivery Indefinite Quantity Contract 80KSC019D0011-80KSC019F0070. This is the first progress report to document on-going SA activities; supplemental progress reports will be provided as additional data is collected. During the SA, a total of six soil, 48 groundwater direct push technology (DPT), eight groundwater monitoring well, and one surface water sample were collected between October 2021 and March 2022. The samples were analyzed for 28 PFAS compounds using the Department of Defense Quality Systems Manual-compliant Method. SA sample results were used along with historical results to evaluate the extent of PFAS impacts to the environment in the FS1 Area. Data generated to date and prior results were screened against the United States Environmental Protection Agency (USEPA) May 2022 Tap Water Regional Screening Levels (RSLs) for groundwater and residential RSLs for soil (hazard quotient of 0.1). Surface water results were screened against the State of Florida Human Health Surface Water Screening Levels (SWSLs). Overall, results from the SA showed exceedances of the applicable screening criteria for soil, groundwater and surface water. Considering the current and historical dataset, perfluorooctanesulfonic acid (PFOS) is the prevalent PFAS compound, which is indicative of AFFF releases. Based on results of the SA, additional groundwater DPT and surface water sampling should be considered, focused on evaluating surface water bodies in the southeast portion of the Industrial Area, which discharge into the Banana River. Additionally, installation of monitoring wells should be considered to evaluate the interaction between groundwater and surface water in the FS1 Area.

PFAS↗

The SSRI Knowledge Base Tool: Current Tool Functionality Review and Planned Future Enhancements

NASA’s Small Satellite Reliability Initiative (SSRI), in conjunction with NASA’s Small Spacecraft Systems Virtual Institute (S3VI), has developed the SSRI Knowledge Base to improve mission confidence for small spacecraft. The SSRI Knowledge Base provides vetted, high-quality sources of information on elements that are key to successful small spacecraft missions. These resources include SSRI working group generated documents and presentations in addition to existing guides, publications, standards, software tools, websites, and books. The Knowledge Base is fully searchable, offers downloadable content when possible, and otherwise links to or references content directly from within the tool. All 58 of the planned topic pages that comprise the SSRI Knowledge Base have been recently completed and include over 450 unique resources that are now available for review. Over the past several months significant enhancements to the tool’s capabilities have been developed and implemented. These enhancements consist of the completed baseline content; development of an Application Programming Interface (API); improved user interfaces; scalable and searchable Best Practices and Lessons Learned (BPLL) lists with ratings; and custom website analytics. The SSRI Knowledge Base is a comprehensive and searchable online tool that consolidates and organizes resources, best practices, and lessons learned from previous small spacecraft missions sponsored by NASA, other government agencies, and academia. This free, publicly available tool is available to the entire SmallSat community at: NASA SSRI Knowledge Base | Explore. This presentation will discuss the motivation for and development of the SSRI Knowledge Base, demonstrate the existing tool, share how the smallsat community can get involved and outline plans for further enhancement development. The SSRI is a collaborative activity with broad participation from civil, Department of Defense, and both national and international commercial space systems providers and stakeholders. The S3VI is jointly sponsored by NASA’s Space Technology Mission Directorate and Science Mission Directorate.

Small Spacecraft↗

The SSRI Knowledge Base Tool: Current Tool Functionality Review and Planned Future Enhancements

NASA’s Small Satellite Reliability Initiative (SSRI), in conjunction with NASA’s Small Spacecraft Systems Virtual Institute (S3VI), has developed the SSRI Knowledge Base to improve mission confidence for small spacecraft. The SSRI Knowledge Base provides vetted, high-quality sources of information on elements that are key to successful small spacecraft missions. These resources include SSRI working group generated documents and presentations in addition to existing guides, publications, standards, software tools, websites, and books. The Knowledge Base is fully searchable, offers downloadable content when possible, and otherwise links to or references content directly from within the tool. All 58 of the planned topic pages that comprise the SSRI Knowledge Base have been recently completed and include over 450 unique resources that are now available for review. Over the past several months significant enhancements to the tool’s capabilities have been developed and implemented. These enhancements consist of the completed baseline content; development of an Application Programming Interface (API); improved user interfaces; scalable and searchable Best Practices and Lessons Learned (BPLL) lists with ratings; and custom website analytics. The SSRI Knowledge Base is a comprehensive and searchable online tool that consolidates and organizes resources, best practices, and lessons learned from previous small spacecraft missions sponsored by NASA, other government agencies, and academia. This free, publicly available tool is available to the entire SmallSat community at: NASA SSRI Knowledge Base | Explore. This presentation will discuss the motivation for and development of the SSRI Knowledge Base, demonstrate the existing tool, share how the smallsat community can get involved and outline plans for further enhancement development. The SSRI is a collaborative activity with broad participation from civil, Department of Defense, and both national and international commercial space systems providers and stakeholders. The S3VI is jointly sponsored by NASA’s Space Technology Mission Directorate and Science Mission Directorate.

Small Spacecraft↗

Conducting the NASP ground test program

The National Aero-Space Plane (NASP) program has recently entered a new phase of the program known as Phase 2D. During this period, five aerospace companies and the Government have formed a National Team. This team has focused on developing a single experimental (X-30) vehicle design and are pursuing a technology validation and demonstration program to prove out the design concepts and design tools. This paper presents an overview of the Phase 2D round testing being conducted to validate the X-30 design and to demonstrate the critical technologies needed to build and fly a research vehicle during Phase 3 of the program. The Phase 2D exit criteria are discussed to identify how they provide top-level guidance for developing the ground test program. An overview of major test facility modifications being performed in support of the test program is also presented. Emphasis is placed on propulsion and structures testing since these are felt to be the primary areas requiring technologies beyond the current state-of-the-art. Also discussed is the use of uncertainty analysis as a method to account for uncertainties in test data. In addition, this paper addresses the use of these uncertainties to develop qualitative indicators of how well the design and technology developed during Phase 2 have matured.

Airframes↗

US Coast Guard GPS Information Center (GPSIC) and its function within the Civil GPS Service (CGS)

In 1987, the U.S. Department of Defense (DOD) formally requested that the U.S. Department of Transportation (DOT) take responsibility for providing an office that would respond to nonmilitary user needs for GPS information, data, and assistance. DOT accepted this responsibility and in February 1989, named the Coast Guard as their lead agency for the project. Since that time, the U.S. Coast Guard has worked with the U.S. Space Command to develop requirements and implement a plan for providing the requested interface with the civil GPS community. The Civil GPS Service (CGS) consists of four main elements: GPS Information Center (GPSIC) - provides GPS status information to civilian users of the system: Civil GPS Service Interface Committee (CGSIC) - established to identify civil GPS user technical information needs in support of the CGS program; Differential GPS (DGPS) - Coast Guard Research and Development Project; and PPS Program Office (PPSPO) - (Under development) will administer the program allowing qualified civil users to have access to the PPS signal. Details about the services these organizations provide are described.

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