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NASA NTRS2001

GEOS Instrument of Opportunity (IoO)

NOAA's three-axis stabilized series of GOES satellites have a place reserved on the Earth-facing side for an Instrument of Opportunity (IoO). The IoO slot is a location for new technologies that provide space-time-spectral resolution of the environment not possible with the preconceived Imager and Sounder. For example, candidate IoO's have usually proposed to use large-format staring arrays of detectors. The size, weight, power, data rate, and interface allocations for the IoO are modest in comparison to the Imager and Sounder, but the resources are large enough to allow for the collection of useful real time data. Because, the geosynchronous location is ideal for monitoring rapidly changing unpredictable events, IoO's have been suggested to detect lightning, volcanism, ozone and sulfur dioxide, ocean color, vegetation, special weather events, and even broadcast color TV. To become an IoO on GOES, the proposed instrument must: 1) have potential benefit to NOAA, 2) fit within the allocation constraints, 3) be independently funded, including pre-launch test equipment and the spacecraft accommodation costs, 4) be delivered two years before launch for integration and testing, and 5) not interfere with the existing launch schedule or the operational instruments.

Chesters, Dennis↗

NASA NTRS2001

A Comparison of the AVS-9 and the Panoramic Night Vision Goggle During Rotorcraft Hover and Landing

The purpose of this flight test was to measure any differences in pilot-vehicle performance and pilot opinion between the use of the current generation AVS-9 Night Vision Goggle and one variant of the prototype Panoramic Night Vision Goggle (the PNV.GII). The PNVGII has more than double the horizontal field-of-view of the AVS-9, but reduced image quality. The flight path of the AH-1S helicopter was used as a measure of pilot-vehicle performance. Also recorded were subjective measures of flying qualities, physical reserves of the pilot, situational awareness, and display usability. Pilot comment and data indicate that the benefits of additional FOV with the PNVGIIs are to some extent negated by the reduced image quality of the PNVGIIs.

Szoboszlay, Zoltan↗

NASA NTRS2001

Enhancement of Tropical Land Cover Mapping with Wavelet-Based Fusion and Unsupervised Clustering of SAR and Landsat Image Data

The characterization and the mapping of land cover/land use of forest areas, such as the Central African rainforest, is a very complex task. This complexity is mainly due to the extent of such areas and, as a consequence, to the lack of full and continuous cloud-free coverage of those large regions by one single remote sensing instrument, In order to provide improved vegetation maps of Central Africa and to develop forest monitoring techniques for applications at the local and regional scales, we propose to utilize multi-sensor remote sensing observations coupled with in-situ data. Fusion and clustering of multi-sensor data are the first steps towards the development of such a forest monitoring system. In this paper, we will describe some preliminary experiments involving the fusion of SAR and Landsat image data of the Lope Reserve in Gabon. Similarly to previous fusion studies, our fusion method is wavelet-based. The fusion provides a new image data set which contains more detailed texture features and preserves the large homogeneous regions that are observed by the Thematic Mapper sensor. The fusion step is followed by unsupervised clustering and provides a vegetation map of the area.

LeMoigne, Jacqueline↗

NASA NTRS2001

Ranges of applicability for the continuum beam model in the mechanics of carbon nanotubes and nanorods

Limitations in the validity of the continuum beam model for carbon nanotubes (NTs) and nanorods are examined. Applicability of all assumptions used in the model is restricted by the two criteria for geometric parameters that characterize the structure of NTs. The key non-dimensional parameters that control the NT buckling behavior are derived via dimensional analysis of the nanomechanical problem. A mechanical law of geometric similitude for NT buckling is extended from continuum mechanics for different molecular structures. A model applicability map, where two classes of beam-like NTs are identified, is constructed for distinct ranges of non-dimensional parameters. Expressions for the critical buckling loads and strains are tailored for two classes of NTs and compared with the data provided by the molecular dynamics simulations. copyright 2001 Elsevier Science Ltd. All rights reserved.

Continuum beam model↗

NASA NTRS2002

Rapid Spacecraft Development: Results and Lessons Learned

The Rapid Spacecraft Development Office (RSDO) at NASA's Goddard Space Flight Center is responsible for the management and direction of a dynamic and versatile program for the definition, competition, and acquisition of multiple indefinite delivery and indefinite quantity contracts - resulting in a catalog of spacecraft buses. Five spacecraft delivery orders have been placed by the RSDO and one spacecraft has been launched. Numerous concept and design studies have been performed, most with the intent of leading to a future spacecraft acquisition. A collection of results and lessons learned is recorded to highlight management techniques, methods and processes employed in the conduct of spacecraft acquisition. Topics include working relationships under fixed price delivery orders, price and value, risk management, contingency reserves, and information restrictions.

Watson, William A.↗

NASA NTRS2001

A Scalable Analysis Toolkit

The Scalable Analysis Toolkit (SAT) project aimed to demonstrate that it is feasible and useful to statically detect software bugs in very large systems. The technical focus of the project was on a relatively new class of constraint-based techniques for analysis software, where the desired facts about programs (e.g., the presence of a particular bug) are phrased as constraint problems to be solved. At the beginning of this project, the most successful forms of formal software analysis were limited forms of automatic theorem proving (as exemplified by the analyses used in language type systems and optimizing compilers), semi-automatic theorem proving for full verification, and model checking. With a few notable exceptions these approaches had not been demonstrated to scale to software systems of even 50,000 lines of code. Realistic approaches to large-scale software analysis cannot hope to make every conceivable formal method scale. Thus, the SAT approach is to mix different methods in one application by using coarse and fast but still adequate methods at the largest scales, and reserving the use of more precise but also more expensive methods at smaller scales for critical aspects (that is, aspects critical to the analysis problem under consideration) of a software system. The principled method proposed for combining a heterogeneous collection of formal systems with different scalability characteristics is mixed constraints. This idea had been used previously in small-scale applications with encouraging results: using mostly coarse methods and narrowly targeted precise methods, useful information (meaning the discovery of bugs in real programs) was obtained with excellent scalability.

Aiken, Alexander↗

NASA NTRS1997

Operational Issues: What Science in Available?

Flight/duty/rest considerations involve two highly complex factors: the diverse demands of aviation operations and human physiology (especially sleep and circadian rhythms). Several core operational issues related to fatigue have been identified, such as minimum rest requirements, duty length, flight time considerations, crossing multiple time zones, and night flying. Operations also can involve on-call reserve status and callout, delays due to unforeseen circumstances (e.g., weather, mechanical), and on-demand flights. Over 40 years of scientific research is now available to apply to these complex issues of flight/duty/rest requirements. This research involves controlled 'laboratory studies, simulations, and data collected during regular flight operations. When flight/duty/rest requirements are determined they are typically based on a variety of considerations, such as operational demand, safety, economic, etc. Rarely has the available, state-of-the-art science been a consideration along with these other factors when determining flight/duty/rest requirements. While the complexity of the operational demand and human physiology precludes an absolute solution, there is an opportunity to take full advantage of the current scientific data. Incorporating these data in a rational operational manner into flight/duty/rest requirements can improve flight crew performance, alertness, and ultimately, aviation safety.

Rosekind, Mark R.↗

NASA NTRS2002

Oxidation Behavior of Copper Alloy Candidates for Rocket Engine Applications (Technical Poster)

A rocket engine's combustion chamber is lined with material that is highly conductive to heat in order to dissipate the huge thermal load (evident in a white-hot exhaust plume). Because of its thermal conductivity copper is the best choice of liner material. However, the mechanical properties of pure copper are inadequate to withstand the high stresses, hence, copper alloys are needed in this application. But copper and its alloys are prone to oxidation and related damage, especially "blanching" (an oxidation-reduction mode of degradation). The space shuttle main engine combustion chamber is lined with a Cu-Ag-Zr alloy, "NARloy-Z", which exhibits blanching. A superior liner is being sought for the next generation of RLVs (Reusable Launch Vehicles) It should have improved mechanical properties and higher resistance to oxidation and blanching, but without substantial penalty in thermal conductivity. GRCop84, a Cu-8Cr-4Nb alloy (Cr2Nb in Cu matrix), developed by NASA Glenn Research Center (GRC) and Case Western Reserve University, is a prime contender for RLV liner material. In this study, the oxidation resistance of GRCop-84 and other related/candidate copper alloys are investigated and compared

Ogbuji, Linus U. J.↗

NASA NTRS2000

Transonic Flow Computations Using Nonlinear Potential Methods

This presentation describes the state of transonic flow simulation using nonlinear potential methods for external aerodynamic applications. The presentation begins with a review of the various potential equation forms (with emphasis on the full potential equation) and includes a discussion of pertinent mathematical characteristics and all derivation assumptions. Impact of the derivation assumptions on simulation accuracy, especially with respect to shock wave capture, is discussed. Key characteristics of all numerical algorithm types used for solving nonlinear potential equations, including steady, unsteady, space marching, and design methods, are described. Both spatial discretization and iteration scheme characteristics are examined. Numerical results for various aerodynamic applications are included throughout the presentation to highlight key discussion points. The presentation ends with concluding remarks and recommendations for future work. Overall. nonlinear potential solvers are efficient, highly developed and routinely used in the aerodynamic design environment for cruise conditions. Published by Elsevier Science Ltd. All rights reserved.

Holst, Terry L.↗

NASA NTRS1996

A Leak Monitor for Industry

GenCorp Aerojet Industrial Products, Lewis Research Center, Marshall Space Flight Center, and Case Western Reserve University developed a gas leak detection system, originally for use with the Space Shuttle propulsion system and reusable launch vehicles. The Model HG200 Automated Gas Leak Detection System has miniaturized sensors that can identify extremely low concentrations of hydrogen without requiring oxygen. A microprocessor-based hardware/software system monitors the sensors and displays the source and magnitude of hydrogen leaks in real time. The system detects trace hydrogen around pipes, connectors, flanges and pressure tanks, and has been used by Ford Motor Company in the production of a natural gas-powered car.

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NASA NTRS1992

Problem-Solving Software

CBR Express software solves problems by adapting sorted solutions to new problems specified by a user. It is applicable to a wide range of situations. The technology was originally developed by Inference Corporation for Johnson Space Center's Advanced Software Development Workstation. The project focused on the reuse of software designs, and Inference used CBR as part of the ACCESS prototype software. The commercial CBR Express is used as a "help desk" for customer support, enabling reuse of existing information when necessary. It has been adopted by several companies, among them American Airlines, which uses it to solve reservation system software problems.

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NASA NTRS1991

Archeological/Environmental Research

Landsat/Seasat remote sensing was used by Ames Research Center to evaluate environmental influence on ancient Mayan civilization. Over 35 archeological sites were imaged and valuable information concerning Maya settlement patterns, environment, and resource usage resulted. The imagery was also used by Mexican authorities to develop coastal management plans, establish Biosphere Reserves and assess damage from the 1988 Hurricane Gilbert. Imagery showed evidence of ancient coastlines, changes in sea level, an ancient river plain and Mayan canal systems. Previously unknown Mayan reservoirs were discovered. The project is considered a pioneering effort combining remote sensing, environmental studies and archeology.

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NASA NTRS2002

How Sample Completeness Affects Gamma-Ray Burst Classification

Unsupervised pattern recognition algorithms support the existence of three gamma-ray burst classes; class I (long, large fluence bursts of intermediate spectral hardness), Class II (short, small fluence, hard bursts), and class III (soft bursts of intermediate durations and fluences). The algorithms surprisingly assign larger membership to class III than to either of the other two classes. A known systematic bias has been previously used to explain the existence of class III in terms of class I; this bias allows the fluences and durations of some bursts to be underestimated. We show that this bias primarily affects only the longest bursts and cannot explain the bulk of the class III properties. We resolve the question of class III existence by demonstrating how samples obtained using standard trigger mechanisms fail to preserve the duration characteristics of small peak flux bursts: (Sample incompleteness is thus primarily responsible for the existence of class III.) In order to avoid this incompleteness, we show how a new dual timescale peak flux can be defined in terms of peak flux and fluence. The dual timescale peak flux reserves the duration distribution of faint bursts and correlates either with spectral hardness (and presumably redshift) than either peak flux or fluence. The techniques presented here are generic and have applicability to the studies of other transient events. The results also indicate that pattern recognition algorithms are sensitive to sample completeness; this can influence the study of large astronomical databases such as those found in a Virtual Observatory.

Hakkila, Jon↗

NASA NTRS1983

Space Technology for Book Preservation

The Library of Congress has patented a process to extend book life. It is called vapor phased deacidification, and involves the use of DEZ (diethyl zinc), a chemical vapor which neutralizes acid and deposits an alkaline reserve on book pages. As the process must be done in an airless environment, the library utilized Goddard Space Flight Center's vacuum chamber for deacidification. The chamber can treat 5,000 books at once, and a new facility is planned. The Library plans to license the technology to private companies; several universities are interested in the process.

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NASA NTRS2003

Satellite-Altitude Geopotential Study of the Kursk Magnetic Anomaly (KMA)

With the successful launch of the Orsted, SAC-C and CHAMP satellites we are able to make both magnetic and gravity anomaly maps of the Earth's crust; magnetic from all three missions and gravity with CHAMP. We have used these data to study the KMA area of Russia. This is an important region for several reasons: (1) we have already made satellite magnetic anomaly maps of this region and they can be integrated with the gravity data from CHAMP for a comprehensive interpretation; (2) KMA contains the largest know reserves of iron-ore in the world; and (3) there are significant ground truth data available for this region from aeromagnetic, balloon surveys and geophysical mapping, including extensive rock magnetic/paleo-magnetic and geologic studies. Utilizing the gravity observations, collocated with the magnetic data enabled us to make a joint interpretation. While there is a high amplitude magnetic anomaly recorded over the KMA the gravity anomaly at satellite altitude revealed by CHAMP is only around 3-6 mGal but is not centered on the magnetic high. This would indicate that despite the fact that in the region of the KMA the rocks have a higher percentage of iron than in the surrounding formations the entire area is Archean-Proterozoic in age and therefore very dense.

Taylor, Patrick T.↗

NASA NTRS2003

Ultrasail

Ultrasail is a complete sail system for the launch, deployment, stabilization and control of very large solar sails enabling reduced mission times for interplanetary and deep space spacecraft. Ultrasail is an innovative, non-traditional approach to propulsion technology achieved by combining propulsion and control systems developed for formation-flying microsatellites with an innovative solar sail architecture to achieve sq km-class controllable sail areas, sail subsystem area densities of 1 gm per sq m, and thrust levels equivalent to 400 kW ion thruster systems used for comparable deep space missions. Ultrasail can conceivably even achieve outer planetary rendezvous, a deep space capability now reserved for high-mass nuclear and chemical systems. Ultrasail is a Delta IV-launched multi-blade spin-stabilized system with blade lengths as long as 50 km, reminiscent of the MacNeal Heliogyro. The primary innovation is the near-elimination of sail supporting structures by attaching the sail tip to a rigid formation-flying microsatellite truss which deploys the sail blade, and which then articulates the blade to provide attitude control, including spin stabilization and precession of the spin axis. These tip microsatellites are controlled by a solar-powered 3-axis microthruster system (electric or cold gas) to maintain proper sail film tension during deployment and spin-up. The satellite mass also provides a stabilizing centrifugal force on the blade while in rotation. Understanding the dynamics of individual blades is key to the overall dynamics of Ultrasail. Forces and torques that must be modeled include those due to solar pressure, those generated by the microsatellite at the blade tip and by torques applied at the blade root. Centrifugal forces also play a significant role in the deployment and maintenance of the sail configuration. To capture the dynamics of the overall system, the equations of motion for the blades have been derived. Using these differential equations, a control law will be derived to maneuver Ultrasail. This law involves the pitching of the individual blades thereby moving the distribution of the radiation pressure on each individual blade and inducing a resultant torque on the system. The direction of the angular momentum vector and its rate of precession can be controlled through the pitch angle of the blades. The Ultrasail trajectory is also being studied. Optimal or near-optimal trajectories are being generated to showcase Ultrasail performance. Various missions, e.g. outer planet and solar polar missions for observation of the Sun, are currently being investigated to demonstrate the performance enhancements generated by Ultrasail technology. Calculus-of-variations-based optimization software is used to produce optimal Ultrasail trajectories. The performance of these trajectories is being compared to optimal results generated with other propulsion models, including chemical propulsion, ion propulsion, and competing solar sail concepts. Results of these studies will quantify the performance of Ultrasail compared to existing solar sail concepts for high energy missions.

Burton, R.↗

NASA NTRS2003

Improving Resource Selection and Scheduling Using Predictions

The introduction of computational grids has resulted in several new problems in the area of scheduling that can be addressed using predictions. The first problem is selecting where to run an application on the many resources available in a grid. Our approach to help address this problem is to provide predictions of when an application would start to execute if submitted to specific scheduled computer systems. The second problem is gaining simultaneous access to multiple computer systems so that distributed applications can be executed. We help address this problem by investigating how to support advance reservations in local scheduling systems. Our approaches to both of these problems are based on predictions for the execution time of applications on space- shared parallel computers. As a side effect of this work, we also discuss how predictions of application run times can be used to improve scheduling performance.

Smith, Warren↗

NASA NTRS2001

The Conference Proceedings of the 2001 Air Transport Research Society (ATRS) of the WCTR Society

The papers presented at this conference include: 1) The Global Airline Company: Agent of Market Power or Competition? 2) Airport Pavement Management; 3) Reservation System Providers and the Impact of Codeshare Arrangements on Screen Display; 4) Strategic Classification of Current Airline Alliances and Examination of Critical Factors Involving the Formations - an Explorative Perspective; 5) Airport Privatization Policy and Performance Measurement in Korea; 6) Pilot and Air Traffic Controller Relationships: The Role of Interdependence and Relative Influence; 7) Liberalization of Air Cargo Services: Background and an Economic Analysis; 8) The Implication of Hub and Spoke Network on the Airline Alliance Strategy.

Lee, Yeong-Heok↗