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At least 1,513 records · Page 84
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Stellar Activity at the End of the Main Sequence: GHRS Observations of the M8 Ve Star VB 10

We present Goddard High Resolution Spectrograph observations of the M8 Ve star VB 10 (equal to G1 752B), located very near the end of the stellar main sequence, and its dM3.5 binary companion G1 752A. These coeval stars provide a test bed for studying whether the outer atmospheres of stars respond to changes in internal structure as stars become fully convective near mass 0.3 solar mass (about spectral type M5), where the nature of the stellar magnetic dynamo presumably changes, and near the transition from red to brown dwarfs near mass 0.08 solar mass (about spectral type M9), when hydrogen burning ceases at the end of the main sequence. We obtain upper limits for the quiescent emission of VB 10 but observe a transition region spectrum during a large flare, which indicates that some type of magnetic dynamo must be present. Two indirect lines of evidence-scaling from the observed X-ray emission and scaling from a time-resolved flare on AD Leo suggest that the fraction of the stellar bolometric luminosity that heats the transition region of VB 10 outside of obvious flares is comparable to, or larger than, that for G1 752A. This suggests an increase in the magnetic heating rates, as measured by L(sub line)/L(sub bol) ratios, across the radiative/convective core boundary and as stars approach the red/brown dwarf boundary. These results provide new constraints for dynamo models and models of coronal and transition-region heating in late-type stars.

Linsky, Jeffrey L.↗
NASA NTRS1995

Intermediate Levels of Autonomy within the SSM/PMAD Breadboard

The Space Station Module Power Management and Distribution (SSM/PMAD) bread-board is a test bed for the development of advanced power system control and automation. Software control in the SSM/PMAD breadboard is through co-operating systems, called Autonomous Agents. Agents can be a mixture of algorithmic software and expert systems. The early SSM/PMAD system was envisioned as being completely autonomous. It soon became apparent, though, that there would always be a need for human intervention, at least as long as a human interacts with the system in any way. In a system designed only for autonomous operation, manual intervention meant taking full control of the whole system, and loosing whatever expertise was in the system. Several methods for allowing humans to interact at an appropriate level of control were developed. This paper examines some of these intermediate modes of autonomy. The least humanly intrusive mode is simple monitoring. The ability to modify future behavior by altering a schedule involves high-level interaction. Modification of operating activities comes next. The coarsest mode of control is individual, unplanned operation of individual Power System components. Each of these levels is integrated into the SSM/PMAD breadboard, with support for the user (such as warnings of the consequences of control decisions) at every level.

Dugal-Whitehead, Norma R.↗
NASA NTRS1997

Wake Vortex Sensors Requirements Overview

The presentation includes discussions of primary wake vortex system requirements, evolution models, sensor evolution, site specific sensor tradeoffs, wake sensor functions, deployment considerations, the operational test bed system and additional sensor requirements.

Hinton, David A.↗
NASA NTRS1998

Neural Network and Regression Approximations in High Speed Civil Transport Aircraft Design Optimization

Nonlinear mathematical-programming-based design optimization can be an elegant method. However, the calculations required to generate the merit function, constraints, and their gradients, which are frequently required, can make the process computational intensive. The computational burden can be greatly reduced by using approximating analyzers derived from an original analyzer utilizing neural networks and linear regression methods. The experience gained from using both of these approximation methods in the design optimization of a high speed civil transport aircraft is the subject of this paper. The Langley Research Center's Flight Optimization System was selected for the aircraft analysis. This software was exercised to generate a set of training data with which a neural network and a regression method were trained, thereby producing the two approximating analyzers. The derived analyzers were coupled to the Lewis Research Center's CometBoards test bed to provide the optimization capability. With the combined software, both approximation methods were examined for use in aircraft design optimization, and both performed satisfactorily. The CPU time for solution of the problem, which had been measured in hours, was reduced to minutes with the neural network approximation and to seconds with the regression method. Instability encountered in the aircraft analysis software at certain design points was also eliminated. On the other hand, there were costs and difficulties associated with training the approximating analyzers. The CPU time required to generate the input-output pairs and to train the approximating analyzers was seven times that required for solution of the problem.

Patniak, Surya N.↗
NASA NTRS1998

Conversions to the Lidar Atmospheric Sensing Experiment (LASE) Instrument for Nadir and Zenith Measurements

LASE now has the advantage of being economically upgraded and customized with COTS hardware and software while using "C" software language. These changes are made so as not to destroy the form, fit and functional characteristics required for flights aboard the ER-2 aircraft. The LASE Instrument can now be quickly adapted to fly onboard ER-2, P-3, C-130 and DC-8 aircraft. The adaptability of the CDS upgraded electronics compliments other modular subsystems like the laser optical bench in that it was designed to be a test bed for new technology lasers.

Moore, Alvah S., Jr.↗
NASA NTRS1998

Atmospheric Depolarization Lidar Experimental Receiver: A Space Shuttle Hitchhiker Payload

Development work is underway at the Goddard Space Flight Center to construct a depolarization measuring atmospheric lidar receiver. The Atmospheric Lidar (AL) is tentatively scheduled to fly on the Space Shuttle in a late-1999 time frame. The AL will fly in conjunction with the Shuttle Laser Altimeter (SLA) and the Infrared Spectral Imaging Radiometer (ISIR) to provide a comprehensive package of atmospheric aerosol and cloud information. The AL operates in conjunction with the SLA laser transmitter and measures profiles of atmospheric backscatter at 532 nm. The receiver system discriminates between the parallel and perpendicular polarizations of the backscattered signal, thus providing depolarization ratios for scattering from clouds. The lidar receiver also provides cloud height and thickness measurements to complement the brightness temperature measurements generated by the ISIR thermal imager. The function of the AL is twofold. The primary function is to provide range-resolved measurements of atmospheric aerosol backscatter and depolarization ratio at 532 nm with 75 m vertical resolution. The scientific purpose of these measurements is to determine composition of clouds based on the depolarization ratio (i.e cloud content is water or ice), to determine cloud height and thickness, and to gain further understanding of the global distribution of aerosols. This information, when coupled with the cloud brightness measured by the ISIR thermal imager will provide a significant amount of information on cloud composition and radiative effects, particularly for cirrus and sub-visual cirrus clouds. A secondary function of the AL is to serve as an in-space test bed for lidar technology advancements, including a fully fiber-coupled receiver and photon counting from space. In addition, the data obtained by the AL will be used to develop software for the Geoscience Laser Altimeter System (GLAS) flight mission.

McGill, Matthew J.↗
NASA NTRS1998

Low Cost Propulsion Technology at the Marshall Space Flight Center: Fastrac Engine and the Propulsion Test Article

The need for low cost access to space has initiated the development of low cost liquid rocket engine and propulsion system hardware at the Marshall Space Flight Center (MSFC). The engine, the 60,000 lbf, RP-1 and LOX Fastrac Engine has been designed as a robust, low cost liquid rocket engine with applications for X-34 as well as future low cost booster systems. The engine is a turbopump fed, gas generator cycle, rocket motor with an ablative nozzle. The Propulsion Test Article (PTA) is a test bed for low cost propulsion system hardware including a composite RP-1 tank, flight feedlines and pressurization system, stacked in a booster configuration. A general description of the PTA and the Fastrac engine is given, with emphasis on the technical specification of the hardware including flow rates, pressures and other operating conditions. The process which has been used for the design and integration of this hardware is described.

Fisher, Mark F.↗
NASA NTRS1993

JSC Director's Discretionary Fund 1992 Annual Report

Annual report of the Johnson Space Center Director's Discretionary Fund documenting effective use of resources. The $1,694,000 funding for FY92 was distributed among 27 projects. The projects are an overall aid to the NASA mission, as well as providing development opportunities for the science and engineering staff with eventual spinoff to commercial uses. Projects described include space-based medical research such as the use of stable isotopes of deuterium and oxygen to measure crew energy use and techniques for noninvasive motion sickness medication. Recycling essentials for space crew support is conducted in the Regenerative Life Support and the Hybrid Regenerative Water Recovery test beds. Two-phase fluid flow simulated under low-gravity conditions, hypervelocity particle impact on open mesh bumpers, and microcalorimetry to measure the long-term hydrazine/material compatibility were investigated. A patent application was made on a shape-memory-alloy release nut. Computer estimate of crew accommodations for advanced concepts was demonstrated. Training techniques were evaluated using multimedia and virtual environment. Upgrades of an electronic still camera provide high resolution images from orbit are presented.

Jenkins, Lyle↗
NASA NTRS1998

Development of a Portable, Ground-Based Ozone Lidar Instrument for Tropospheric Ozone Research and Educational Training

The objective of this project is to develop a portable, eye-safe, ground-based ozone lidar instrument specialized for ozone differential absorption lidar (DIAL) measurements in the troposphere. This prototype instrument is intended to operate at remote field sites and to serve as the basic unit for monitoring projects requiring multi-instrument networks, such as that discussed in the science plan for the Global Tropospheric Ozone Project (GTOP). This instrument will be based at HU for student training in lidar technology as well as atmospheric ozone data analysis and interpretation. It will be also available for off-site measurement campaigns and will serve as a test bed for further instrument development. Later development beyond this grant to extend the scientific usefulness of the instrument may include incorporation of an aerosol channel and upgrading the laser to make stratospheric ozone measurements. Undergraduate and graduate students have been and will be active participants in this research effort.

Chyba, Thomas↗
NASA NTRS1998

STS-95 Day 05 Highlights

On this fifth day of the STS-95 mission, the flight crew, Cmdr. Curtis L. Brown, Pilot Steven W. Lindsey, Mission Specialists Scott E. Parazynski, Stephen K. Robinson, and Pedro Duque, and Payload Specialists Chiaki Mukai and John H. Glenn, check the status of components of the Hubble Space Telescope Orbital Systems Test (HOST) payload, which provides an on-orbit test bed for hardware that will be used during the third Hubble servicing mission. Then Parazynski and Pilot Steve Lindsey set up some of the tools that will be used during the rendezvous and subsequent capture and reberthing of the Spartan satellite.

Source record↗
NASA NTRS1998

Tone Noise and Nearfield Pressure Produced by Jet-Cavity Interaction

Cavity flow resonance can cause numerous problems in aerospace applications. While our long-term goal is to understand cavity flows well enough to devise effective cavity resonance suppression techniques, this paper describes a fundamental study of resonant tones produced by jet-cavity interaction at subsonic and supersonic speeds. Our specific jet-cavity configuration can also be used as a test bed for evaluating active and passive flow resonance control concepts. Two significant findings emerge from this study. 1) Originally, we expected that tones produced by jet-cavity interaction would resemble cavity tones or jet tones or would involve some simple combinations of each. The experimental data do not support these expectations: instead, the jet cavity interaction produce a unique set of tones. We propose simple yet and physically insightful correlations for these tones. Although the pressure patterns on the cavity floor display very complex variations with the Mach number for a length/depth = 8 cavity, the tones correspond to the acoustic modes of the cavity-independent of flow. For a length/ depth = 3 cavity, however, a surprise emerges: the pressure patterns on the cavity floor are not so complex but the tones depend significantly on the flow. Additionally, we examine the role of external feedback unique to jet-cavity interaction. 2) Previous research led us to expect that traditional classifications (open, transitional, or closed) for cavities in an infinite flight stream would be insensitive to small changes in Mach number and would depend primarily on cavity length/depth ratios. Use of the novel high resolution photoluminescent pressure sensitive paint shows that the classifications are actually quite sensitive to jet Mach number for a length/depth = 8 cavity. However, these classifications provide no guidance whatsoever for tone amplitude or frequency. Detailed experimental data and insights presented here will assist researchers who are performing numerical simulations of jet-cavity flows as a first step toward devising resonance suppression methods.

Raman, Ganesh↗
NASA NTRS1997

Reusable Launch Vehicle Technology Program

Industry/NASA reusable launch vehicle (RLV) technology program efforts are underway to design, test, and develop technologies and concepts for viable commercial launch systems that also satisfy national needs at acceptable recurring costs. Significant progress has been made in understanding the technical challenges of fully reusable launch systems and the accompanying management and operational approaches for achieving a low cost program. This paper reviews the current status of the RLV technology program including the DC-XA, X-33 and X-34 flight systems and associated technology programs. It addresses the specific technologies being tested that address the technical and operability challenges of reusable launch systems including reusable cryogenic propellant tanks, composite structures, thermal protection systems, improved propulsion and subsystem operability enhancements. The recently concluded DC-XA test program demonstrated some of these technologies in ground and flight test. Contracts were awarded recently for both the X-33 and X-34 flight demonstrator systems. The Orbital Sciences Corporation X-34 flight test vehicle will demonstrate an air-launched reusable vehicle capable of flight to speeds of Mach 8. The Lockheed-Martin X-33 flight test vehicle will expand the test envelope for critical technologies to flight speeds of Mach 15. A propulsion program to test the X-33 linear aerospike rocket engine using a NASA SR-71 high speed aircraft as a test bed is also discussed. The paper also describes the management and operational approaches that address the challenge of new cost effective, reusable launch vehicle systems.

Freeman, Delma C., Jr.↗
NASA NTRS1998

Spectrum Preprocessing in the OPAD System

To determine the readiness of a rocket engine, and facilitate decisions on continued use of the engine before servicing is required, high-resolution optical spectrometers are used to acquire spectra from the exhaust plume. Such instruments are in place at the Technology Test Bed (TTB) stand at Marshall Space Flight Center (MSFC) and the A1 stand at Stennis Space Center (SSC). The optical spectrometers in place have a wide wavelength range covering the visible and near-infrared regions, taking approximately 8000 measurements at about one Angstrom spacing every half second. In the early stages of this work, data analysis was done manually. A simple spectral model produced a theoretical spectrum for given amount of elements and an operator visually matched the theoretical and real spectra. Currently, extensive software is being developed to receive data from the spectrometer and automatically generate an estimate of element amounts in the plume. It will result in fast and reliable analysis, with the capability of real-time performance. This software is the result of efforts of several groups but mainly it has been developed and used by scientists and combustion engineers, in their effort of understanding the underlying physical processes and phenomena and creating visualization and report generation facilities. Most of the software has been developed using the IDL language and programming environment which allows for extensive data visualization. Although this environment has been very beneficial, the resulting programs execute very slowly and are not easily portable to more popular, real-time environments. The need for portability and high speed of execution is becoming more apparent as the software matures moving out of the experimentation stage and into the production stage where ease of use and short response time are the most desirable features. The purpose of the work described here is to assist the scientists who developed the original IDL-based version in the conversion of the software into the real-time, production version. Specifically, a section of the software devoted to the preprocessing of the spectra has been converted into the C language. In addition, parts of this software which may be improved have been identified, and recommendations are given to improve the functionality and ease of use of the new version.

Katsinis, Constantine↗
NASA NTRS1998

X-34 Program Status

The National Aeronautics and Space Administration (NASA) initiated the current X-34 program in 1996 as part of the U.S. space agency's effort to dramatically reduce the cost of access to space. The X-34 is the first in a series of "Pathfinder" vehicles designed to conduct flight testing of key launch vehicle technologies at low cost. The X-34 program has moved rapidly from the drawing board to hardware build-up, with the first flight scheduled for 1999. The development of the X-34 has been accomplished by a unique blend of industry and government organizations and personnel working closely together. The program will provide rocket powered winged vehicles that can fly sub-orbital missions in support of advanced reusable launch vehicle technology development. In addition, the X-34 vehicles will represent a hypersonic test bed for advanced experiments in the aeronautical sciences.

London, John R., III↗
NASA NTRS1998

Educational Applications on the World Wide Web: An Example Using Amphion

There is a great deal of excitement about using the internet and the World Wide Web in education. There are such exciting possibilities and there is a wealth and variety of material up on the web. There are however many problems, problems of access and resources, problems of quality -- for every excellent resource there are many poor ones, and there are insufficiently explored problems of teacher training and motivation. For example, Wiesenmayer and Meadows report on a study of 347 West Virginia science teachers. These teachers were enrolled in a week-long summer workshop to introduce them to the internet and its educational potential. The teachers were asked to review science sites as to overall quality and then about their usefulness in their own classrooms. The teachers were enthusiastic about the web, and gave two-thirds of the sites high ratings, and essentially all the rest average ratings. But alarmingly, over 80% of these sites were viewed as having no direct applicability in the teacher's own classroom. This summer I was assigned to work on the Amphion project in the Automated Software Engineering Group under the leadership of Michael Lowry. I wished to find educational applications of the Amphion system, which in its current implementation can be used to create fortran programs and animations using the SPICE libraries created by the NAIF group at JPL. I wished to find an application which provided real added educational value, which was in line with educational curriculum standards and which would serve a documented need of the educational community. The application selected was teaching about the causes of the seasons -- at the approximately the fourth, fifth, sixth grade level. This topic was chosen because it is in line with national curriculum standards. The fourth, fifth, sixth grade level was selected to coincide with the grade level served by the Ames Aerospace Encounter, which services 10,000 children a year on field trips. The hope is that eventually the Ames Aerospace Encounter could be used as a test bed for the lessons developed. The topic is one which is difficult to teach and the necessity for new methods is documented in the educational literature. Current educational standards indicate that seasons should be part of the elementary school curriculum.

Friedman, Jane↗
NASA NTRS1999

Noise Certification Predictions for FJX-2-Powered Aircraft Using Analytic Methods

Williams International Co. is currently developing the 700-pound thrust class FJX-2 turbofan engine for the general Aviation Propulsion Program's Turbine Engine Element. As part of the 1996 NASA-Williams cooperative working agreement, NASA agreed to analytically calculate the noise certification levels of the FJX-2-powered V-Jet II test bed aircraft. Although the V-Jet II is a demonstration aircraft that is unlikely to be produced and certified, the noise results presented here may be considered to be representative of the noise levels of small, general aviation jet aircraft that the FJX-2 would power. A single engine variant of the V-Jet II, the V-Jet I concept airplane, is also considered. Reported in this paper are the analytically predicted FJX-2/V-Jet noise levels appropriate for Federal Aviation Regulation certification. Also reported are FJX-2/V-Jet noise levels using noise metrics appropriate for the propeller-driven aircraft that will be its major market competition, as well as a sensitivity analysis of the certification noise levels to major system uncertainties.

Berton, Jeffrey J.↗
NASA NTRS1999

Propulsion Research and Technology: Overview

Propulsion is unique in being the main delimiter on how far and how fast one can travel in space. It is the lack of truly economical high-performance propulsion systems that continues to limit and restrict the extent of human endeavors in space. Therefore the goal of propulsion research is to conceive and investigate new, revolutionary propulsion concepts. This presentation reviews the development of new propulsion concepts. Some of these concepts are: (1) Rocket-based Combined Cycle (RBCC) propulsion, (2) Alternative combined Cycle engines suc2 as the methanol ramjet , and the liquid air cycle engines, (3) Laser propulsion, (4) Maglifter, (5) pulse detonation engines, (6) solar thermal propulsion, (7) multipurpose hydrogen test bed (MHTB) and other low-G cryogenic fluids, (8) Electric propulsion, (9) nuclear propulsion, (10) Fusion Propulsion, and (11) Antimatter technology. The efforts of the NASA centers in this research is also spotlighted.

Cole, John↗