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Software independent verification and validation (IV and V) implementation methods, specific approaches and accomplishments in the application of IV and V to NASA programs are discussed. Because software is mission critical, software assurance is a critical aspect of NASA's safety and mission assurance program. An overview of NASA's software IV and V facility is given.
To address concerns about time and expense associated with software aspects of certification, the Federal Aviation Administration (FAA) began the Streamlining Software Aspects of Certification (SSAC) program. As part of this program, a Technical Team was established to determine whether the cost and time associated with certifying aircraft can be reduced while maintaining or improving safety, with the intent of impacting the FAA's Flight 2000 program. The Technical Team conducted a workshop to gain a better understanding of the major concerns in industry about software cost and schedule. Over 120 people attended the workshop, including representatives from the FAA,commercial transport and general aviation aircraft manufacturers and suppliers, and procurers and developers of non-airborne systems; and, more than 200 issues about software aspects of certification were recorded. This paper provides an overview of the SSAC program, motivation for the workshop, details of the workshop activities and outcomes, and recommendations for follow-on work.
One of the major concerns of any maintenance organization is to understand and estimate the cost of maintenance releases of software systems. Planning the next release so as to maximize the increase in functionality and the improvement in quality are vital to successful maintenance management. The objective of this paper is to present the results of a case study in which an incremental approach was used to better understand the effort distribution of releases and build a predictive effort model for software maintenance releases. This study was conducted in the Flight Dynamics Division (FDD) of NASA Goddard Space Flight Center(GSFC). This paper presents three main results: 1) a predictive effort model developed for the FDD's software maintenance release process; 2) measurement-based lessons learned about the maintenance process in the FDD; and 3) a set of lessons learned about the establishment of a measurement-based software maintenance improvement program. In addition, this study provides insights and guidelines for obtaining similar results in other maintenance organizations.
Flight software (FSW) is a mission critical element of spacecraft functionality and performance. When ground operations personnel interface to a spacecraft, they are dealing almost entirely with onboard software. This software, even more than ground/flight communications systems, is expected to perform perfectly at all times during all phases of on-orbit mission life. Due to the fact that FSW can be reconfigured and reprogrammed to accommodate new spacecraft conditions, the on-orbit FSW maintenance team is usually significantly responsible for the long-term success of a science mission. Failure of FSW can result in very expensive operations work-around costs and lost science opportunities. There are three basic approaches to staffing on-orbit software maintenance, namely: (1) using the original developers, (2) using mission operations personnel, or (3) assembling a Center of Excellence for multi-spacecraft on-orbit FSW support. This paper explains a National Aeronautics and Space Administration, Goddard Space Flight Center (NASA/GSFC) experience related to the roles of on-orbit FSW maintenance personnel. It identifies the advantages and disadvantages of each of the three approaches to staffing the FSW roles, and demonstrates how a cost efficient on-orbit FSW Maintenance Center of Excellence can be established and maintained with significant return on the investment.
The broad objective of this expert system software based application was to demonstrate the enhancements and cost savings that can be achieved through expert system software utilization in a spacecraft ground control center. Spacelab provided a valuable proving ground for this advanced software technology; a technology that will be exploited and expanded for future ISS operations. Our specific focus was on demonstrating payload cadre command and control efficiency improvements through the use of "smart" software which monitors flight telemetry, provides enhanced schematic-based data visualization, and performs advanced engineering data analysis.
Originally, this project was to produce an animated Powerpoint presentation of the 'Shuttle Engine and its Software' and to produce a web page with animation including the same materials but with greater detail in the description of the software. The principal emphasis was to be on the web page. Midway through the first year of the project, we were advised by the technical coordinator of this work at MSFC to concentrate on the web page alone. Also, the project was expanded to include a web presentation of the MRECS (Modular Rocket Control System). For the SSME project, the web page presentation has been completed. The integration of the animation into the web page is complete although we have been asked to speed up the animation. Also, the addition of greater detail to the description of the SSME controller software has been added. Much of the work on this program was done by students as their task for their senior project course, the capstone course of their program of study. The students gained a great deal from this project. They have learned to use VISIO, POWERPOINT, PHOTOSHOP, and several web page software packages. The starting point for this project was a PowerPoint presentation by the PI while on a Summer Faculty Fellowship at MSFC. For this project, about half of the drawings of the SSME were improved and about half were completely redrawn. The original still drawings have been animated to illustrate the fuel flow through the SSME system.
This report describes the software products, system architectures and operational procedures developed by Lockheed-Martin in support of the Roll-Out and Turn-Off (ROTO) sub-element of the Low Visibility Landing and Surface Operations (LVLASO) program at the NASA Langley Research Center. The ROTO portion of this program focuses on developing technologies that aid pilots in the task of managing the deceleration of an aircraft to a pre-selected exit taxiway. This report focuses on software that produces a system of redundant deceleration cues for a pilot during the landing roll-out, and presents these cues on a head up display (HUD). The software also produces symbology for aircraft operational phases involving cruise flight, approach, takeoff, and go-around. The algorithms and data sources used to compute the deceleration guidance and generate the displays are discussed. Examples of the display formats and symbology options are presented. Logic diagrams describing the design of the ROTO software module are also given.
This paper discusses the following topics: (1) Autonomy for Future Missions- Mars Outposts, Titan Aerobot, and Europa Cryobot / Hydrobot; (2) Emergence of Autonomy- Remote Agent Architecture, Closing Loops Onboard, and New Millennium Flight Experiment; and (3) Software Engineering Challenges- Influence of Remote Agent, Scalable Autonomy, Autonomy Software Validation, Analytic Verification Technology, and Autonomy and Software Software Engineering.
A comprehensive package of scalable overset grid CFD software is reviewed. The software facilitates accurate simulation of complete aircraft aerodynamics, including viscous effects, unsteadiness, and relative motion between component parts. The software significantly lowers the manpower and computer costs normally associated with such efforts. The software is discussed in terms of current capabilities and planned future enhancements.
The Payload Planning System is for experiment planning on the International Space Station. The planning process has a number of different aspects which need to be stored in a database which is then used to generate reports on the planning process in a variety of formats. This process is currently structured as a 3-tier client/server software architecture comprised of a Java applet at the front end, a Java server in the middle, and an Oracle database in the third tier. This system presently uses CGI, the Common Gateway Interface, to communicate between the user-interface and server tiers and Active Data Objects (ADO) to communicate between the server and database tiers. This project investigated other methods and tools for performing the communications between the three tiers of the current system so that both the system performance and software development time could be improved. We specifically found that for the hardware and software platforms that PPS is required to run on, the best solution is to use Java Remote Method Invocation (RMI) for communication between the client and server and SQLJ (Structured Query Language for Java) for server interaction with the database. Prototype implementations showed that RMI combined with SQLJ significantly improved performance and also greatly facilitated construction of the communication software.
NASA and its international partners will increasingly depend on software-based systems to implement advanced functions for future space missions, such as Martian rovers that autonomously navigate long distances exploring geographic features formed by surface water early in the planet's history. The software-based functions for these missions will need to be robust and highly reliable, raising significant challenges in the context of recent Mars mission failures attributed to software faults. After reviewing these challenges, this paper describes tools that have been developed at NASA Ames that could contribute to meeting these challenges; 1) Program synthesis tools based on automated inference that generate documentation for manual review and annotations for automated certification. 2) Model-checking tools for concurrent object-oriented software that achieve memorability through synergy with program abstraction and static analysis tools.
The utility of software primarily depends on its reliability and performance; whereas, its significance depends solely on its credibility for intended use. The credibility of simulations confirms the credibility of software. The level of veracity and the level of validity of simulations determine the degree of credibility of simulations. The process of assessing this credibility in fields such as computational mechanics (CM) differs from that followed by the Defense Modeling and Simulation Office in operations research. Verification and validation (V&V) of CM simulations is not the same as V&V of CM software. Uncertainty is the measure of simulation credibility. Designers who use software are concerned with management of simulation uncertainty. Terminology and concepts are presented with a few examples from computational fluid dynamics.
AgentBuilder is a software component developed under an SBIR contract between Reticular Systems, Inc., and Goddard Space Flight Center. AgentBuilder allows software developers without experience in intelligent agent technologies to easily build software applications using intelligent agents. Agents are components of software that will perform tasks automatically, with no intervention or command from a user. AgentBuilder reduces the time and cost of developing agent systems and provides a simple mechanism for implementing high-performance agent systems.
001 is an integrated tool suited for automatically developing ultra reliable models, simulations and software systems. Developed and marketed by Hamilton Technologies, Inc. (HTI), it has been applied in engineering, manufacturing, banking and software tools development. The software provides the ability to simplify the complex. A system developed with 001 can be a prototype or fully developed with production quality code. It is free of interface errors, consistent, logically complete and has no data or control flow errors. Systems can be designed, developed and maintained with maximum productivity. Margaret Hamilton, President of Hamilton Technologies, also directed the research and development of USE.IT, an earlier product which was the first computer aided software engineering product in the industry to concentrate on automatically supporting the development of an ultrareliable system throughout its life cycle. Both products originated in NASA technology developed under a Johnson Space Center contract.
The Marshall Space Flight Center's (MSFC) Payload Operations Center (POC) ground system has evolved over a period of about 10 years. During this time the software processes have migrated from more traditional to more contemporary development processes in an effort to minimize unnecessary overhead while maximizing process benefits. The Software processes that have evolved still emphasize requirements capture, software configuration management, design documenting, and making sure the products that have been developed are accountable to initial requirements. This paper will give an overview of how the Software Processes have evolved, highlighting the positives as well as the negatives. In addition, we will mention the COTS tools that have been integrated into the processes and how the COTS have provided value to the project.
The Marshall Space Flight Center's (MSFC) Payload Operations Center (POC) ground system has been developed and has evolved over a period of about 10 years. During this time the software processes have migrated from more traditional to more contemporary development processes. The new Software processes still emphasize requirements capture, software configuration management, design documenting, and making sure the products that have been developed are accountable to initial requirements. This paper will give an overview of how the Software Process have evolved highlighting the positives as well as the negatives. In addition, we will mention the COTS tools that have been integrated into the processes and how the COTS have provided value to the project .
The paper will provide an overview of the web-based distributed simulation software system developed for end-to-end, multi-spacecraft mission design, analysis, and test at the NASA Goddard Space Flight Center (GSFC). This software system was developed for an internal research and development (IR&D) activity at GSFC called the Distributed Space Systems (DSS) Distributed Synthesis Environment (DSE). The long-term goal of the DSS-DSE is to integrate existing GSFC stand-alone test beds, models, and simulation systems to create a "hands on", end-to-end simulation environment for mission design, trade studies and simulations. The short-term goal of the DSE was therefore to develop the system architecture, and then to prototype the core software simulation capability based on a distributed computing approach, with demonstrations of some key capabilities by the end of Fiscal Year 2002 (FY02). To achieve the DSS-DSE IR&D objective, the team adopted a reference model and mission upon which FY02 capabilities were developed. The software was prototyped according to the reference model, and demonstrations were conducted for the reference mission to validate interfaces, concepts, etc. The reference model, illustrated in Fig. 1, included both space and ground elements, with functional capabilities such as spacecraft dynamics and control, science data collection, space-to-space and space-to-ground communications, mission operations, science operations, and data processing, archival and distribution addressed.
A collaborative software development approach is described. The software product is an adaptation of proven computational capabilities combined with new capabilities to form the Agency's next generation aerothermodynamic and aerodynamic analysis and design tools. To efficiently produce a cohesive, robust, and extensible software suite, the approach uses agile software development techniques; specifically, project retrospectives, the Scrum status meeting format, and a subset of Extreme Programming's coding practices are employed. Examples are provided which demonstrate the substantial benefits derived from employing these practices. Also included is a discussion of issues encountered when porting legacy Fortran 77 code to Fortran 95 and a Fortran 95 coding standard.