ALBERT

Description: In this viewgraph presentation, information is provided on the numerical simulation of a turbulence event encountered by NASA Langley's B-757 while conducting flight tests in areas at high risk for severe turbulence. Specific details on the Terminal Area Simulation System (TASS) show how the simulation is devised. The 100 m simulation was able to observe large-scale features.

Description: This viewgraph presentation provides information on two experiments on the effectiveness of a cockpit weather information system on a simulated general aviation flight. The presentation covers the simulation hardware configuration, the display device screen layout, a mission scenario, conclusions, and recommendations. The second experiment, with its own scenario and conclusions, is a follow-on experiment.

Description: The 2003 Solar System Exploration Decadal Survey ('SSEDS') emphasizes the significant science available from Jupiter deep entry probes. Studies performed at JPL this year identified a mission design that would allow JIMO to deliver and support one or more entry probes that reach the 100-bar level in Jupiter's atmosphere, with relatively minor modifications to JIMO s preliminary mission design. Notably, the icy moon tour mission design, beginning with Callisto approach, is unaffected. This proposed mission design would offer the option of adding a rich new set of high-priority SSEDS science objectives to the planned JIMO mission for a relatively small investment.

Description: We present a preliminary design and mission description for Icy Satellites Impactor Probes (IPS). This design addresses two of the scientific themes of this Icy Galilean Satellites Forum: Surface Chemistry and Geophysics, and Interior Structures. Impactor probes may also make significant contributions in the areas of surface geology and mineralogy.

Description: The spacecraft was nearly integrated and had passed some of its early mechanical and electrical testing. One of its instruments, the Proportional Counter Array (PCA), had a gas leak in one of the five proportional counter modules that made up the array. The science division where the instrument was being developed wanted a gas replenishment system added to assure the PCA would last for the entire mission. Adding a gas replenishment system would mean interrupting spacecraft integration and testing; developing a new subsystem and integrating it onto the spacecraft; modifying all the PCA modules; including a complex integration of the instrument onto the spacecraft; and implementing a more complex performance and environmental test process. It was the wrong answer because it made a simple design more complex and added little value to the mission at a major cost in time and dollars. Our mission couldn't afford the additional budget and schedule risks. XTE was the latest of a long line of projects being managed by my Explorer Program Office, but it was unique in being the first project we had agreed to do for a fixed price. NASA HQ agreed, in return, to provide us with the funding profile we needed to make it happen. We were both trying to break the unhealthy spiral in the Explorer program that saw current missions overrunning and pushing subsequent missions downstream to the point where their science was becoming marginal. The science community was upset and wanted better performance from NASA. I summarized my arguments to the director. The Engineering Directorate had taken responsibility for the spacecraft development when we established XTE as an in-house project at Goddard Space Flight Center, and also was supporting the PCA development. "It adds complexity," I reiterated. "It's a significant cost impact for only a marginal reliability increase". His response was music to my ears, "Jim, I won't stand in your way, but you'll have to convince the scientists and engineers."

Description: We present an iterative technique in which model checking and static analysis are combined to verify large software systems. The role of the static analysis is to compute partial order information which the model checker uses to reduce the state space. During exploration, the model checker also computes aliasing information that it gives to the static analyzer which can then refine its analysis. The result of this refined analysis is then fed back to the model checker which updates its partial order reduction. At each step of this iterative process, the static analysis computes optimistic information which results in an unsafe reduction of the state space. However we show that the process converges to a fired point at which time the partial order information is safe and the whole state space is explored.

Description: Most evolutionary approaches to fault recovery in FPGAs focus on evolving alternative logic configurations as opposed to evolving the intra-cell routing. Since the majority of transistors in a typical FPGA are dedicated to interconnect, nearly 80% according to one estimate, evolutionary fault-recovery systems should benefit hy accommodating routing. In this paper, we propose an evolutionary fault-recovery system employing a genetic representation that takes into account both logic and routing configurations. Experiments were run using a software model of the Xilinx Virtex FPGA. We report that using four Virtex combinational logic blocks, we were able to evolve a 100% accurate quadrature decoder finite state machine in the presence of a stuck-at-zero fault.

Description: In this paper, we will summarize the software trends and their impact on the cost of developing flight and ground software.

Description: This paper reports on a simple, low-cost effort to streamline the configuration of the uplink software tools. Even though the existing ground system consisted of JPL and custom Cassini software rather than COTS, we chose a glueware approach--reintegrating with wrappers and bridges and adding minimal new functionality.

Description: This paper reports on a simple, low-cost effort to streamline the configuration of the uplink software tools.

Description: In this survey paper, we bring together current progress to date in identifying design patterns for use with the real-time specification for Java in a format consistent with contemporary patterns descriptions.

Description: This work involves developing representative mission-critical spacecraft software using the Real-Time Specification for Java.

Description: This paper presents a Software Management and Implementation Plan (SIMP) for managing and controlling the development of the Microwave Limb Sounder (MLS) instrument software, and the Instrument Ground Support Equipment (IGSE) software.

Description: The identification of patterns of software defect data yields insights into improving the quality of both operational and future spacecraft. This paper describes the results of applying this technique to both post-launch and pre-launch spacecraft. It then describes four key challenges that remain to achieving fuller utilization of defect analysis in future systems.

Description: Driven by a need to explore and develop propulsion systems that exceeded current computing capabilities, NASA Glenn embarked on a novel strategy leading to the development of an architecture that enables propulsion simulations never thought possible before. Full engine 3 Dimensional Computational Fluid Dynamic propulsion system simulations were deemed impossible due to the impracticality of the hardware and software computing systems required. However, with a software paradigm shift and an embracing of parallel and distributed processing, an architecture was designed to meet the needs of future propulsion system modeling. The author suggests that the architecture designed at the NASA Glenn Research Center for propulsion system modeling has potential for impacting the direction of development of affordable weapons systems currently under consideration by the Applied Vehicle Technology Panel (AVT).

Description: This paper focuses on one possible approach based on a LEO constellation composed of 100 spacecraft.

Description: Space microgravity missions are designed to provide a microgravity environment for scientific experiments, but these missions cannot provide a perfect environment, due to vibrations caused by crew activity, on-board experiments, support systems (pumps, fans, etc.), periodic orbital maneuvers, and water dumps. Therefore, it is necessary to predict the impact of these vibrations on space experiments, prior to performing them. Simulations were conducted to study the effect of the vibrations on the directional solidification of a dendritic alloy. Finite element ca!cu!attie?ls were dme with a simd2titcr based on a continuum model of dendritic solidification, using the Fractional Step Method (FSM). The FSM splits the solution of the momentum equation into two steps: the viscous intermediate step, which does not enforce continuity; and the inviscid projection step, which calculates the pressure and enforces continuity. The FSM provides significant computational benefits for predicting flows in a directionally solidified alloy, compared to other methods presently employed, because of the efficiency gains in the uncoupled solution of velocity and pressure. finite differences, arises when the interdendritic liquid reaches the eutectic temperature and concentration. When a node reaches eutectic temperature, it is assumed that the solidification of the eutectic liquid continues at constant temperature until all the eutectic is solidified. With this approach, solidification is not achieved continuously across an element; rather, the element is not considered solidified until the eutectic isotherm overtakes the top nodes. For microgravity simulations, where the convection is driven by shrinkage, it introduces large variations in the fluid velocity. When the eutectic isotherm reaches a node, all the eutectic must be solidified in a short period, causing an abrupt increase in velocity. To overcome this difficulty, we employed a scheme to numerically predict a more accurate value for the rate of change of fraction of liquid as the liquid in an element solidifies. The new method enables us to contrast results of simulations in which the alloy is subjected to no gravity or a steady-state acceleration versus simulations when the alloy is subjected to vibration disturbances; therefore, the effect of vibration disturbances can be assessed more accurately. To assess the impact of these vibration-perturbations, transient accelerometer data from a space shuttle mission are used as inputs for the simulation model. These on-orbit acceleration data were obtained from the Microgravity Science Division at Glenn Research Center (GRC- MSD) and are applied to the buoyancy term of the momentum equation in a simulation of a Pb-5.8 wt. % Sb alloy that solidifies in a thermal gradient of 4000 K/m and a translation velocity of 3 p d s . Figure 2 shows the vertical velocity of a node that begins in the all-liquid region and subsequently solidifies; the vibrations are applied at 5000 seconds in this simulation. An important difficulty, common to all solidification models based on finite elements or 2 The magnitudes of the velocity oscillations that are vibration-induced are very small and acceptable. The biggest concern is whether the concentration of the liquid near the dendrite tips is distorted because of the vibration-induced perturbations. Results for this case show no concentration oscillations present in the all-liquid region.

Description: The Real-Time Specification for Java (RTSJ) provides facilities for deterministic, real-time execution in a language that is otherwise subject to variable latencies in memory allocation and garbage collection.

Description: We have successfully demonstrated a portion of the spacecraft attitude control and fault protection, running on a standard Java platform, and are currently in the process of taking advantage of the features provided by the RTSJ.

Description: This document discusses the verification of the Secure Socket Layer (SSL) communication protocol as a demonstration of the Model Based Verification (MBV) portion of the verification instrument set being developed under the Reducing Software Security Risk (RSSR) Trough an Integrated Approach research initiative. Code Q of the National Aeronautics and Space Administration (NASA) funds this project. The NASA Goddard Independent Verification and Validation (IV&V) facility manages this research program at the NASA agency level and the Assurance Technology Program Office (ATPO) manages the research locally at the Jet Propulsion Laboratory (California institute of Technology) where the research is being carried out.

Description: Composite pressure vessels, used extensively for gas and fuel containment in space vehicles, are generally constructed with a metallic liner, while the fiber reinforcement carries the major portion of the pressure-induced load. The design is dominated by the liner s low strain at yield since the reinforcing fibers cannot operate at their potential load-bearing capability without resorting to pre-stressing (or autofrettaging). An ultra high-efficiency pressure vessel, which operates at the optimum strain capability of the fibers, can be potentially achieved with a liner-less construction. This paper discusses the design and manufacturing challenges to be overcome in the development of such a pressure vessel. These include: (1) gas/liquid containment and permeation, (2) design and structural analysis, and (3) manufacturing process development. The paper also presents the development and validation tests on a liner-less pressure vessel developed by Kaiser Compositek Inc. (KCI). It should be noted that KCI s liner-less tank exhibits a highly controlled leak-before-burst mode. This feature results in a structure having the highest level of safety.

Description: In this paper we discuss the methods developed for the production of the INTEGRAL/SPI instrument response. The response files were produced using a suite of Monte Carlo simulation software developed at NASA/GSFC based on the GEANT-3 package available from CERN. The production of the INTEGRAL/SPI instrument response also required the development of a detailed computer mass model for SPI. We discuss ow extensive investigations into methods to reduce both the computation time and storage requirements for the SPI response. We also discuss corrections to the simulated response based on our comparison of ground and infiight Calibration data with MGEANT simulations.

Description: Citizen Explorer-I (CX-I), designed and built by students at Colorado Space Grant Consortium in Boulder to provide global ozone monitoring, employs a unique mission architecture and several innovative technologies during its mission. The mission design allows K-12 schools around the world to be involved as ground stations available to receive science data and telemetry from CX-I. Another important technology allows the spacecraft to be less reliant on ground operators. Spacecraft Command Language (SCL) allows mission designers to set constraints on the satellite operations. The satellite then automatically adheres to the constraints when the satellite is out of contact with Mission Operations. In addition to SCL, a low level of artificial intelligence will be supplied to the spacecraft through the use of the Automated Scheduling and Planning ENvironment (ASPEN). ASPEN is used to maintain a spacecraft schedule in order to achieve the objectives a mission operator would normally have to complete. Within the communications system of CX-I, internet of CX-I, internet protocols are the main method for communicating with the satellite. As internet protocols have not been widely used in satellite communication, CX-I provides an opportunity to study the effectiveness of using internet protocols over radio links. The Attitude Determination and Control System (ADCS) on CX-I uses a gravity gradient boom as a means of orienting the satellite's science instruments toward nadir. The boom design is unique because it is constructed of tape measure material. These new technologies' effectiveness will be tested for use on future small satellite projects within the space satellite industry.

Description: Traditional techniques for designing resonant edge-slot waveguide arrays have required an iterative trial-and-error process of measuring slot data from several prototypes. Since very little meaningful data has been published, this technology remains relatively immature and prohibitive for many smaller programs that could benefit from some advantages this antenna has to offer. A new Computer-Aided Design technique for designing resonant edge-slot waveguide arrays was used to successfuliy design such an X-band radiometer antenna for the NASA Light Rainfall Radiometer (LRR) instrument. Having the ability to rapidly create such an extremely accurate and efficient antenna design without the need to manufacture prototypes has also enabled inexpensive research that promises to improve the system-level performance of microwave radiometers for upcoming space-flight missions. This paper will present details of the LRR antenna design and describe some other current edge-slot array accomplishments at Goddard Space Flight Center.

Description: The Wilkinson Microwave Anisotropy Probe mission produces a map of the cosmic microwave background radiation over the entire celestial sphere by executing a fast spin and a slow precession of its spin axis about the Sun line to obtain a highly interconnected set of measurements. The spacecraft attitude is sensed and controlled using an inertial reference unit, two star trackers, a digital sun sensor, twelve coarse sun sensors, three reaction wheel assemblies, and a propulsion system. Sufficient attitude knowledge is provided to yield instrument pointing to a standard deviation (l sigma) of 1.3 arc-minutes per axis. In addition, the spacecraft acquires and holds the sunline at initial acquisition and in the event of a failure, and slews to the proper orbit adjust orientations and to the proper off-sunline attitude to start the compound spin. This paper presents an overview of the design of the attitude control system to carry out this mission and presents some early flight experience.

Description: This viewgraph presentation reviews the efforts of Ames Research Center to develop Slender Hypersonic Aerothermodynamic Research Probes (SHARP) technologies as applied to the new Crew Transfer Vehicle (CTV). Amongst these technologies are ultra high temperature ceramics (UHTC). The results of Computational Fluid Dynamic simulations on prospective designs of the CTV are shown as well as wind tunnel test results.

Description: High temperature structural seals are necessary in many aerospace and aeronautical applications to minimize any detrimental effects originating from undesired leakage. The NASA Glenn Research Center has been and continues to be a pioneer in the development and evaluation of these types of seals. The current focus for the development of structural seals is for the 3rd Generation Reusable Launch Vehicle (RLV), which is scheduled to replace the current space shuttle system by 2025. Specific areas of development under this program include seals for propulsion systems (such as the hypersonic air-breathing ISTAR engine concept based upon Rocket Based Combined Cycle technology) and control surface seals for spacecraft including the autonomous rescue X-38 Crew Return Vehicle and the X-37 Space Maneuver Vehicle.

Description: A formulation of finite-rate ablation surface boundary conditions, including oxidation, nitridation, and sublimation of carbonaceous material with pyrolysis gas injection, has been developed based on surface species mass conservation. These surface boundary conditions are discretized and integrated with a Navier-Stokes solver. This numerical procedure can predict aerothermal heating, chemical species concentration, and carbonaceous material ablation rate over the heatshield surface of re-entry space vehicles. In this study, the gas-gas and gas-surface interactions are established for air flow over a carbon-phenolic heatshield. Two finite-rate gas-surface interaction models are considered in the present study. The first model is based on the work of Park, and the second model includes the kinetics suggested by Zhluktov and Abe. Nineteen gas phase chemical reactions and four gas-surface interactions are considered in the present model. There is a total of fourteen gas phase chemical species, including five species for air and nine species for ablation products. Three test cases are studied in this paper. The first case is a graphite test model in the arc-jet stream; the second is a light weight Phenolic Impregnated Carbon Ablator at the Stardust re-entry peak heating conditions, and the third is a fully dense carbon-phenolic heatshield at the peak heating point of a proposed Mars Sample Return Earth Entry Vehicle. Predictions based on both finite-rate gas- surface interaction models are compared with those obtained using B' tables, which were created based on the chemical equilibrium assumption. Stagnation point convective heat fluxes predicted using Park's finite-rate model are far below those obtained from chemical equilibrium B' tables and Zhluktov's model. Recession predictions from Zhluktov's model are generally lower than those obtained from Park's model and chemical equilibrium B' tables. The effect of species mass diffusion on predicted ablation rate is also examined.

Description: A team was created to participate in the Mars Scout Opportunity. Trade studies determined that an aircraft provided the best opportunity to complete the science objectives of the team. A high fidelity six degree of freedom flight simulation was required to provide credible evidence that the aircraft design fulfilled mission objectives and to support the aircraft design process by providing performance evaluations. The team created the simulation using the Langley Standard Real-Time Simulation in C++ (LaSRS++) application framework. A rapid prototyping approach was necessary because the team had only three months to both develop the aircraft simulation model and evaluate aircraft performance as the design and mission parameters matured. The design of LaSRS++ enabled rapid-prototyping in several ways. First, the framework allowed component models to be designed, implemented, unit-tested, and integrated quickly. Next, the framework provides a highly reusable infrastructure that allowed developers to maximize code reuse while concentrating on aircraft and mission specific features. Finally, the framework reduces risk by providing reusable components that allow developers to build a quality product with a compressed testing cycle that relies heavily on unit testing of new components.

Description: We are developing software to explore the fault tolerance of quantum dot cellular automata gate architectures in the presence of manufacturing variations and device defects. The Topology Optimization Methodology using Applied Statistics (TOMAS) framework extends the capabilities of the A Quantum Interconnected Network Array Simulator (AQUINAS) by adding front-end and back-end software and creating an environment that integrates all of these components. The front-end tools establish all simulation parameters, configure the simulation system, automate the Monte Carlo generation of simulation files, and execute the simulation of these files. The back-end tools perform automated data parsing, statistical analysis and report generation.

Description: Members of the Commercial Technology Office at the NASA Glenn Research Center have developed an exciting new tool that greatly reduces the lead time in creating and routing Space Act Agreements. The Space Act Agreement Maker (SAAM) is an e-government Web-based system that automates the initial drafting of Space Act Agreements by technical and program personnel. SAAM also is used for editing and will be used later for maintaining electronic copies of all Space Act Agreements. During the initial drafting, the software prompts NASA personnel proposing an agreement to answer questions regarding the agreement. On the basis of the answers, the software selects from a matrix of NASA standard clauses to produce a first draft of the agreement. The draft agreement and information submitted by the NASA personnel are electronically routed to Glenn s Commercial Technology Office for review and, where necessary, editing. The final version of the agreement, along with any supporting documentation, is then routed for electronic concurrence/approval to the necessary internal review participants using the electronic routing system (e-router). SAAM was developed cooperatively by Glenn s Commercial Technology Office and Glenn s Office of Chief Counsel. Currently, SAAM is being evaluated by the NASA Headquarters General Counsel Office for use at all NASA centers. This system allows for the effective processing of Space Act Agreements for NASA s internal and external customers. Document control is maintained by a database. With SAAM s electronic routing, review times can be reduced significantly, allowing Glenn to more rapidly establish partnerships with industry. Prior to the creation of SAAM, it took several hours to draft a Space Act Agreement. With SAAM in place, the document can be written in about 30 min. Using the e-router also saves time in determining where the agreement is in the routing process. The document can be tracked easily, and delays can be avoided. Important research with industry partners can commence quickly after preliminary discussions have been held. The development of these products is in line with the expanding e-government initiative that is part of the Presidential Management Agenda. By using this product, NASA researchers can secure greater support from industry and academia partners. The Space Act Agreement Maker has been very well received at NASA Headquarters and at some of the other NASA centers as well. We anticipate that the NASA Ames Research Center will have the system in place very soon, and that some of the other centers will use SAAM in the near future. The General Counsel s office at NASA Headquarters has encouraged the Glenn team to develop a similar system for processing patent licenses. Find out more about Glenn's Technology Transfer & Partnership Office http://technology.grc.nasa.gov/.

Description: Despite the fanciful predictions of Eugen Sanger, Wernher von Braun, and a wealth of science fiction novelists, it was not until the mid-1950s that the first piloted spacecraft design was undertaken in earnest. It was the height of the Cold War, and the paranoia that swept the country and the military had resulted in the largest arms race the world had ever seen. In aviation the desire was to go higher, faster, and farther than ever before. In response to a need for basic research into the ever-increasing speeds and altitudes, the National Advisory Committee on Aeronautics (NACA) began preliminary research into a piloted vehicle that could exceed five times the speed of sound. The research was felt necessary to support both unmanned missile programs and the eventual development of hypersonic combat aircraft. Interestingly, the group of researchers that took the lead in developing the concept (led by John V. Becker) at the NACA s Langley Laboratory added a new wrinkle-they wanted to be able to leave the sensible atmosphere for a few minutes in order to gain a preliminary understanding of space flight2 At the time it was generally felt that piloted space flight would not take place until the turn of the century, although contemporary science fiction-a genre that enjoyed a resurgence of popularity in the mid-1 950s-usually showed it coming much earlier. In fact, many serious researchers believed that the group at Langley should remove the "space leap" from their concept for a hypersonic research air~lane.~ However, the basic designs for a very high speed airplane and for one capable of short excursions outside the atmosphere were not radically different, so the capability remained.

Description: Technological advances over the next 10 to 15 years promise to enable a number of smaller, more capable science missions to the outer planets. With the inception of miniaturized spacecraft for a wide range of applications, both in large clusters around Earth, and for deep space missions, NASA is currently in the process of redefining the way science is being gathered. Technologies such as 3-Dimensional Multi-Chip Modules, Micro-machined Electromechanical Devices, Multi Functional Structures, miniaturized transponders, miniaturized propulsion systems, variable emissivity thermal coatings, and artificial intelligence systems are currently in research and development, and are scheduled to fly (or have flown) in a number of missions. This study will leverage on these and other technologies in the design of a lightweight Neptune orbiter unlike any other that has been proposed to date. The Neptune/Triton Explorer (NExTEP) spacecraft uses solar electric earth gravity assist and aero capture maneuvers to achieve its intended target orbit. Either a Taurus or Delta-class launch vehicle may be used to accomplish the mission.

Description: ANTS (Autonomous Nano-Technology Swarm), a large (1000 member) swarm of nano to picoclass (10 to 1 kg) totally autonomous spacecraft, are being developed as a NASA advanced mission concept. ANTS, based on a hierarchical insect social order, use an evolvable, self-similar, hierarchical neural system in which individual spacecraft represent the highest level nodes. ANTS uses swarm intelligence attained through collective, cooperative interactions of the nodes at all levels of the system. At the highest levels this can take the form of cooperative, collective behavior among the individual spacecraft in a very large constellation. The ANTS neural architecture is designed for totally autonomous operation of complex systems including spacecraft constellations. The ANTS (Autonomous Nano Technology Swarm) concept has a number of possible applications. A version of ANTS designed for surveying and determining the resource potential of the asteroid belt, called PAM (Prospecting ANTS Mission), is examined here.

Description: The objective is to develop in cooperation with other NASA centers a distributed computational environment capable of executing full 3-D aerospace propulsion applications.

Description: The HiVy toolset provides model checking for statecharts. This is achieved by translating statechart specifications into the input language of the spin model checker.

Description: Over the past several years, we have been developing methods of predicting the fault content of software systems based on measured characteristics of their structural evolution.

Description: Over the past several years, we have focused on developing fault models for space mission software. In general, these models use measurable attributes of a software system and its development process to estimate the number of faults inserted into the system during its development; their outputs can be used to better estimate the resources to be allocated to fault identification and removal for all system components.

Description: This paper describes the approach and algorithms used to generalize the paired ratio comparison matrix technique to use information inherent in multiple estimates, multiple reference projects, and estimator range information to generate estimated effort and size distributions.

Description: This paper reports on the results of a follow up study conducted on seven JPL missions completed on or near launch since 1999. The objective is to determine to what extent the recommendations were implemented and whether they had any impact.

Description: This work involves developing representative mission-critical spacecraft software using the Real-Time Specification for Java (RTSJ). This work currently leverages actual flight software used in the design of actual flight software in the NASA's Deep Space 1 (DSI), which flew in 1998.

Description: This paper offers an informal discussion of non-compositional constraints in hopes of making the concept more familiar and accessible.

Description: In the complex environment of JPL's flight missions with increasing dependency on advanced software designs, traditional software validation methods of simulation and testing are being stretched to adequately cover the needs of software development.

Description: We advocate the use of risk-based reasoning to help make good architectural decisions. We explore the adaptation of a risk management process and tool to this purpose.

Description: In this paper, we analyze the measurements of structural evolution and fault couts obtained from the JPL flight software technology development effort.

Description: This paper deals only with the pointing error contribution due to errors in predicting the impact location and describes the acquisition of optical data of the Impactor and associated errors using the flyby instruments; the algorithm for autonomously computing a pointing correction; the expected uncertainty in predicting the impact location; the uncertainty in the flyby pointing correction, and hence the improvement in performance.

Description: Open architectures are gaining popularity for Integrated Vehicle Health Management (IVHM) applications due to the diversity of subsystem health monitoring strategies in use and the need to integrate a variety of techniques at the system health management level. The basic concept of an open architecture suggests that whatever monitoring or reasoning strategy a subsystem wishes to deploy, the system architecture will support the needs of that subsystem and will be capable of transmitting subsystem health status across subsystem boundaries and up to the system level for system-wide fault identification and diagnosis. There is a need to understand the capabilities of various reasoning engines and how they, coupled with intelligent monitoring techniques, can support fault detection and system level fault management. Researchers in IVHM at NASA Ames Research Center are supporting the development of an IVHM system for liquefying-fuel hybrid rockets. In the initial stage of this project, a few readily available reasoning engines were studied to assess candidate technologies for application in next generation launch systems. Three tools representing the spectrum of model-based reasoning approaches, from a quantitative simulation based approach to a graph-based fault propagation technique, were applied to model the behavior of the Hybrid Combustion Facility testbed at Ames. This paper summarizes the characterization of the modeling process for each of the techniques.

Description: This viewgraph presentation provides an overview of the design and development process for NASA's MerBoard. These devices are large interactive display screens which can be shown on the user's computer, which will allow scientists in many locations to interpret and evaluate mission data in real-time. These tools are scheduled to be used during the 2003 Mars Exploration Rover (MER) expeditions. Topics covered include: mission overview, Mer Human Centered Computers, FIDO 2001 observations and MerBoard prototypes.

Description: NASA has developed new technology that improves upon weakness in current mainstream supercomputer designs: those of "scalability," "humadmachine interface," and "load balancing." The system simplifies running large computer simulations of national and international importance like climate prediction and space vehicle design.

Description: Efficient management of large-scale, distributed data storage and processing systems is a major challenge for many computational applications. Many of these systems are characterized by multi-resource tasks processed across a heterogeneous network. Conventional approaches, such as load balancing, work well for centralized, single resource problems, but breakdown in the more general case. In addition, most approaches are often based on heuristics which do not directly attempt to optimize the world utility. In this paper, we propose an agent based control system using the theory of collectives. We configure the servers of our network with agents who make local job scheduling decisions. These decisions are based on local goals which are constructed to be aligned with the objective of optimizing the overall efficiency of the system. We demonstrate that multi-agent systems in which all the agents attempt to optimize the same global utility function (team game) only marginally outperform conventional load balancing. On the other hand, agents configured using collectives outperform both team games and load balancing (by up to four times for the latter), despite their distributed nature and their limited access to information.

Description: Following a description of the science drive which originated the Swift Mission, this is US NASA MIDEX Mission with the collaboration of Italy and the UK, we will describe the status of the hardware and the observing strategy. The telemetry is carried out via the TDRSS satellite for those communications that need immediate response. The data transfer and the scheduled uploading of routine commands will be done through the ASI Malindi station in Kenia. Both in the US and in Europe a large effort will be done to follow the bursts with the maximum of efficiency and as soon as possible after the alert. We will describe how the ESO VLT telescopes are able to respond to the alert. To address the problematic of the dark bursts and to immediately follow up all of the bursts also in the Near Infrared we designed and built a 60 cm NIR Robotic telescope, REM, to be located on the ESO ground at Cerro La Silla. The instrumentation includes also a low dispersion spectrograph with the capability of multi wavelength optical photometry.

Description: The continuing development of microsatellites and nanosatellites for low Earth orbits requires the collection of sufficient power for instruments onboard a low-weight, low-volume spacecraft. Because the overall surface area of a microsatellite or nanosatellite is small, body-mounted solar cells cannot provide enough power. The deployment of traditional, rigid, solar arrays necessitates larger satellite volumes and weights, and also requires extra apparatus for pointing. One solution to this power choke problem is the deployment of a spherical, inflatable power system. This power system, termed the "PowerSphere," has several advantages, including a high collection area, low weight and stowage volume, and the elimination of solar array pointing mechanisms.

Description: To characterize the stress corrosion parameters and predict the life of a sapphire window being considered for use in the International Space Station's Fluids and Combustion Facility, researchers at the NASA Glenn Research Center conducted stress corrosion tests, fracture toughness tests, and reliability analyses, as shown in the figures. Standardized test methods, developed and updated by the author under the auspices of American Society for Testing and Materials, were employed. One interesting finding is that sapphire exhibits a susceptibility to stress corrosion in water similar to that of glass. In addition to generating the stress corrosion parameters and fracture toughness data, closed-form expressions for the variances of the crack growth parameters were derived. The expressions allow confidence bands to be easily placed on life predictions of ceramic components. Brittle materials such as sapphire and quartz are required for windows in a variety of applications such as the Fluids and Combustion Facility. To minimize the launch weight of such facilities, researchers must design the windows to be as lightweight as possible. The safe use of lightweight, brittle windows in structural applications is limited by two factors: low fracture toughness and slow crack growth, or stress corrosion. Stress corrosion of these and other optical materials can occur in relatively common environments, such as humid air. Access to the data has been requested by designers for use in the life prediction of a Northrop Grumman F16 instrument window and a Jet Propulsion Laboratory instrument window. One Space Act Agreement has been formed. Future work includes the measurement of the life of subscale windows.

Description: NASA Glenn Research Center's Computational Materials Group has integrated a graphical user interface with in-house-developed surface modeling capabilities, with the goal of using computationally efficient atomistic simulations to aid the development of advanced aerospace materials, through the modeling of alloy surfaces, surface alloys, and segregation. The software is also ideal for modeling nanomaterials, since surface and interfacial effects can dominate material behavior and properties at this level. Through the combination of an accurate atomistic surface modeling methodology and an efficient computational engine, it is now possible to directly model these types of surface phenomenon and metallic nanostructures without a supercomputer. Fulfilling a High Operating Temperature Propulsion Components (HOTPC) project level-I milestone, a graphical user interface was created for a suite of quantum approximate atomistic materials modeling Fortran programs developed at Glenn. The resulting "Alloy Design Workbench-Surface Modeling Package" (ADW-SMP) is the combination of proven quantum approximate Bozzolo-Ferrante-Smith (BFS) algorithms (refs. 1 and 2) with a productivity-enhancing graphical front end. Written in the portable, platform independent Java programming language, the graphical user interface calls on extensively tested Fortran programs running in the background for the detailed computational tasks. Designed to run on desktop computers, the package has been deployed on PC, Mac, and SGI computer systems. The graphical user interface integrates two modes of computational materials exploration. One mode uses Monte Carlo simulations to determine lowest energy equilibrium configurations. The second approach is an interactive "what if" comparison of atomic configuration energies, designed to provide real-time insight into the underlying drivers of alloying processes.

Description: Lattice Boltzmann (LB) Method is a relatively new method for flow simulations. The start point of LB method is statistic mechanics and Boltzmann equation. The LB method tries to set up its model at molecular scale and simulate the flow at macroscopic scale. LBM has been applied to mostly incompressible flows and simple geometry.

Description: The objective of GRC CNIS/IE work is to build a plug-n-play infrastructure that provides the Grand Challenge Applications with a suite of tools for coupling codes together, numerical zooming between fidelity of codes and gaining deployment of these simulations onto the Information Power Grid. The GRC CNIS/IE work will streamline and improve this process by providing tighter integration of various tools through the use of object oriented design of component models and data objects and through the use of CORBA (Common Object Request Broker Architecture).

Description: This document is a quick reference guide with an overview of the processes required to certify safety-critical and mission-critical flight software at selected NASA centers and the FAA. Researchers and software developers can use this guide to jumpstart their understanding of how to get new or enhanced software onboard an aircraft or spacecraft. The introduction contains aerospace industry definitions of safety and safety-critical software, as well as, the current rationale for certification of safety-critical software. The Standards for Safety-Critical Aerospace Software section lists and describes current standards including NASA standards and RTCA DO-178B. The Mission-Critical versus Safety-Critical software section explains the difference between two important classes of software: safety-critical software involving the potential for loss of life due to software failure and mission-critical software involving the potential for aborting a mission due to software failure. The DO-178B Safety-critical Certification Requirements section describes special processes and methods required to obtain a safety-critical certification for aerospace software flying on vehicles under auspices of the FAA. The final two sections give an overview of the certification process used at Dryden Flight Research Center and the approval process at the Jet Propulsion Lab (JPL).

Description: The objective is to increase the usability of the current NPSS code/architecture by incorporating an advanced space transportation propulsion system capability into the existing NPSS code and begin defining advanced capabilities for NPSS and provide an enhancement for the NPSS code/architecture.

Description: The goal was to perform 3D simulation of GE90 combustor, as part of full turbofan engine simulation. Requirements of high fidelity as well as fast turn-around time require massively parallel code. National Combustion Code (NCC) was chosen for this task as supports up to 999 processors and includes state-of-the-art combustion models. Also required is ability to take inlet conditions from compressor code and give exit conditions to turbine code.

Description: NASA is currently developing technologies for the 3rd Generation Reusable Launch Vehicle (RLV) that is being designed to enter service around the year 2025. In particular, NASA's Glenn Research Center (GRC) is working on advanced high temperature structural seal designs including propulsion system and control surface seals. Propulsion system seals are required along the edges of movable panels in advanced engines, while control surface seals seal the edges and hinge lines of movables flaps and elevons on the vehicle. The overall goal is to develop reusable, resilient seals capable of operating at temperatures up to 2000 F. High temperature seal preloading devices (e.g., springs) are also being evaluated as a means of improving seal resiliency. In order to evaluate existing and potential new seal designs, GRC has designed and is installing several new test rigs capable of simulating the types of conditions that the seals would endure during service including temperatures, pressures, and scrubbing. Two new rigs, the hot compression test rig and the hot scrub test rig, will be used to perform seal compression and scrub tests for many cycles at temperatures up to 3000 F. Another new test rig allows simultaneous flow and scrub tests to be performed on the seals at room temperature to evaluate how the flow blocking performance of the seals varies as they accumulate damage during scrubbing. This presentation will give an overview of these advanced seal development efforts.

Description: This distribution contains several simulation models created for the hybrid simulation language, Hybrid Concurrent Constraint (HCC). An HCC model contains the information specified in the widely-accepted academic definition of a hybrid system: this includes expressions for the modes of the systems to be simulated and the differential equations that apply in each mode. These expressions are written in the HCC syntax. The models included here were created by either applying basic physical laws or implementing equations listed in previously published papers.

Description: We report on a study to determine the maturity of different verification and validation technologies (V&V) on a representative example of NASA flight software. The study consisted of a controlled experiment where three technologies (static analysis, runtime analysis and model checking) were compared to traditional testing with respect to their ability to find seeded errors in a prototype Mars Rover. What makes this study unique is that it is the first (to the best of our knowledge) to do a controlled experiment to compare formal methods based tools to testing on a realistic industrial-size example where the emphasis was on collecting as much data on the performance of the tools and the participants as possible. The paper includes a description of the Rover code that was analyzed, the tools used as well as a detailed description of the experimental setup and the results. Due to the complexity of setting up the experiment, our results can not be generalized, but we believe it can still serve as a valuable point of reference for future studies of this kind. It did confirm the belief we had that advanced tools can outperform testing when trying to locate concurrency errors. Furthermore the results of the experiment inspired a novel framework for testing the next generation of the Rover.

Description: To achieve its science objectives in deep space exploration, NASA has a need for science platform vehicles to autonomously make control decisions in a time frame that excludes intervention from Earth-based controllers. Round-trip light-time is one significant factor motivating autonomy capability, another factor is the need to reduce ground support operations cost. An unsolved problem potentially impeding the adoption of autonomy capability is the verification and validation of such software systems, which exhibit far more behaviors (and hence distinct execution paths in the software) than is typical in current deepspace platforms. Hence the need for a study to benchmark advanced Verification and Validation (V&V) tools on representative autonomy software. The objective of the study was to access the maturity of different technologies, to provide data indicative of potential synergies between them, and to identify gaps in the technologies with respect to the challenge of autonomy V&V. The study consisted of two parts: first, a set of relatively independent case studies of different tools on the same autonomy code, second a carefully controlled experiment with human participants on a subset of these technologies. This paper describes the second part of the study. Overall, nearly four hundred hours of data on human use of three different advanced V&V tools were accumulated, with a control group that used conventional testing methods. The experiment simulated four independent V&V teams debugging three successive versions of an executive controller for a Martian Rover. Defects were carefully seeded into the three versions based on a profile of defects from CVS logs that occurred in the actual development of the executive controller. The rest of the document is structured a s follows. In section 2 and 3, we respectively describe the tools used in the study and the rover software that was analyzed. In section 4 the methodology for the experiment is described; this includes the code preparation, seeding of defects, participant training and experimental setup. Next we give a qualitative overview of how the experiment went from the point of view of each technology; model checking (section 5), static analysis (section 6), runtime analysis (section 7) and testing (section 8). The find section gives some preliminary quantitative results on how the tools compared.

Description: Technology development is inevitably a dynamic process in search of an elusive goal. It is never truly clear whether the need for a particular technology drives its development, or the existence of a new capability initiates new applications. Technology development for the thermal control of spacecraft presents an excellent example of this situation. Nevertheless, it is imperative to have a basic plan to help guide and focus such an effort. Although this plan will be a living document that changes with time to reflect technological developments, perceived needs, perceived opportunities, and the ever-changing funding environment, it is still a very useful tool. This presentation summarizes the current efforts at NASA/Goddard and NASA/JPL to develop new thermal control technology for future robotic NASA missions.

Description: This viewgraph presentation attempts to develop a model of factors which need to be considered in the design and construction of spacecraft to lessen the effects of space weather on these vehicles. Topics considered include: space environments and effects, radiation environments and effects, space weather drivers, space weather models, climate models, solar proton activity and mission design for the GOES mission. The authors conclude that space environment models need to address issues from mission planning through operations and a program to develop and validate authoritative space environment models for application to spacecraft design does not exist at this time.

Description: NASA Ames Research Center is one of NASA s oldest centers, having started out as part of the National Advisory Committee on Aeronautics, (NACA). The site, about 40 miles south of San Francisco, still houses many wind tunnels and other aviation related departments. In recent years, with the growing realization that space exploration is heavily dependent on computing and data analysis, its focus has turned more towards Information Technology. The Computational Sciences Division has expanded rapidly as a result. In this article, I will give a brief overview of some of the past and present projects with a Bayesian content. Much more than is described here goes on with the Division. The web pages at http://ic.arc. nasa.gov give more information on these, and the other Division projects.

Description: In order to promote NASA-wide educational outreach program to educate and inform the public of space exploration, NASA, at Kennedy Space Center, is seeking efficient ways to add more contents to the web by streaming audio/video files. This project proposes a high level overview of a framework for the creation, management, and scheduling of audio/video assets over the web. To support short-term goals, the prototype of a web-based tool is designed and demonstrated to automate the process of streaming audio/video files. The tool provides web-enabled users interfaces to manage video assets, create publishable schedules of video assets for streaming, and schedule the streaming events. These operations are performed on user-defined and system-derived metadata of audio/video assets stored in a relational database while the assets reside on separate repository. The prototype tool is designed using ColdFusion 5.0.

Description: Space-based Telemetry And Range Safety (STARS) is a Kennedy Space Center (KSC) led proof-of-concept demonstration, which utilizes NASA's space network of Tracking and Data Relay Satellites (TDRS) as a pathway for launch and mission related information streams. Flight Demonstration 1 concluded on July 15,2003 with the seventh flight of a Low Power Transmitter (LPT) a Command and Data Handler (C&DH), a twelve channel GPS receiver and associated power supplies and amplifiers. The equipment flew on NASA's F-I5 aircraft at the Dryden Flight Research Center located at Edwards Air Force Base in California. During this NASA-ASEE Faculty Fellowship, the author participated in the collection and analysis of data from the seven flights comprising Flight Demonstration 1. Specifically, the author examined the forward and return links bit energy E(sub B) (in Watt-seconds) divided by the ambient radio frequency noise N(sub 0) (in Watts / Hertz). E(sub b)/N(sub 0) is commonly thought of as a signal-to-noise parameter, which characterizes a particular received radio frequency (RF) link. Outputs from the data analysis include the construction of time lines for all flights, production of graphs of range safety values for all seven flights, histograms of range safety E(sub b)/N(sub 0) values in five dB increments, calculation of associated averages and standard deviations, production of graphs of range user E(sub b)/N(sub 0) values for the all flights, production of graphs of AGC's and E(sub b)/N(sub 0) estimates for flight 1, recorded onboard, transmitted directly to the launch head and transmitted through TDRS. The data and graphs are being used to draw conclusions related to a lower than expected signal strength seen in the range safety return link.

Description: This tutorial provides an overview of the PVS strategy language, and explains how to define new PVS strategies and load them into PVS, and how to create a strategy package. It then discusses several useful techniques that can be used in developing user strategies, and provides examples that illustrate many of these techniques.

Description: steady increase in computational power of general purpose computers, our ability to analyze routine software artifacts is also steadily increasing. As a result, we are witnessing a shift in emphasis from the verification of abstract hand-built models of code, towards the direct verification of implementation level code. This change in emphasis poses a new set of challenges in software verification. We explore some of them in this paper.

Description: This study benchmarks several FSS techniques and reports several studies where a large set metrics were reduced to a handful with little loss of detection accuracy. This result raises the possibility that software defect detection may be much simpler than previously believed.

Description: This paper focuses on describing the custom software tool, DDP, that was developed to support the TIMA process, and on showing how the needs of the TIMA process have influenced the development of the structure and capabilities of the DDP software.

Description: APGEN (Activity Plan GENerator - 314), a multi-mission planning tool, must interface with external software to vest serve its users. AP-GEN's original method for incorporating external software, the User-Defined library mechanism, has been very successful in allowing APGEN users access to external software functionality.

Description: This paper describes the architecture of the JPL multi-mission sequencing system and the sequence automation process, discusses the cost savings associated with both of these changes.

Description: A common science data processing software framework yields the benefits of reuse while remaining adaptable to address requirements that are unique to the mission.

Description: The RTSJ is a specification for supporting real-time execution in the Java programming language. The specification has been shaped by several guiding principles, particularly: predictable execution as the first priority in all tradeoffs, no syntactic extensions to Java, and backward compatibility.