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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Local oscillator distribution using a geostationary satellite

A satellite communication system suitable for distribution of local oscillator reference signals for a widely spaced microwave array has been developed and tested experimentally. The system uses a round-trip correction method of the satellite This experiment was carried out using Telstar-5, a commercial Ku-band geostationary satellite. For this initial experiment, both earth stations were located at the same site to facilitate direct comparison of the received signals. The local oscillator reference frequency was chosen to be 300MHz and was sent as the difference between two Ku-band tones. The residual error after applying the round trip correction has been measured to be better than 3psec for integration times ranging from 1 to 2000 seconds. For integration times greater then 500 seconds, the system outperforms a pair of hydrogen masers with the limitation believed to be ground-based equipment phase stability. The idea of distributing local oscillators using a geostationary satellite is not new; several researchers experimented with this technique in the eighties, but the achieved accuracy was 3 to 100 times worse than the present results. Since substantially and the performance of various components has improved. An important factor is the leasing of small amounts of satellite communication bandwidth. We lease three 100kHz bands at approximately one hundredth the cost of a full 36 MHz transponder. Further tests of the system using terminal separated by large distances and comparison tests with two hydrogen masers and radio interferometry is needed.

hydrogen maser↗
NASA NTRS1987

TAVERNS and the space station software support environment

The Space Station Information System (SSIS) provides the data processing capability for the Space Station Program (SSP). The Software Support Environment (SSE) System for the SSP is the collection of software, procedures, standards, hardware specification, documentation, policy, and training materials. The Ada programming language was baselined by the Space Station Program Office as the language for development and maintenance of all space station software including the software of the SSE itself. The Test And Validation Environment for Remote Networked Systems (TAVERNS) is a distributed philosophy for development and validation of Ada applications software for the space station and as such is closely related to the SSE. An overview of the system is provided.

Howes, Norman R.↗
NASA NTRS2015

Conceptual Design Aspects of Three General Sub-Classes of Multi-Rotor Configurations: Distributed, Modular, and Heterogeneous

Quadcopters and other multi-rotor configurations are poised to make a substantial contribution to commercial and public service aviation. Small multi-rotor configurations already see almost ubiquitous use as radio-controlled toys and hobbyist platforms. In particular, their use as flying cameras has seen rapid adoption by the public. But their greatest contribution to our society may likely be seen in public service missionsapplications. Their potential utility for supporting emergency response missions is discussed in some detail. The multi-rotor design space is then explored from high-level perspective with the emphasis on distributed, modular, and heterogeneous multi-rotor systems. Following this design space examination, a number of specific, detailed technical issues related multi-rotor conceptual design and sizing is also considered.

Configurations↗
NASA NTRSDate not supplied

SpaceFOM: An Interoperability Standard for Space Systems Simulations

There is a long history of simulation supporting space systems development. This includes relatively simple parametric simulations to more complex trajectory simulations to large scale integrated vehicle simulation. One area of relatively recent development is in the area of distributed or interoperable simulation. Distributed simulation has been in wide use by the US military for years but is being used more broadly in the aerospace community. To support large scale distributed simulation, the military community has developed a number of standards to support a-priori interoperability between large collections of disparate simulations. For example, the IEEE 1516 High Level Architecture (HLA) and the Real-time Platform Reference Federation Object Model (RPR FOM). While HLA is suitable for space systems, there are a number of design decisions made in the development of the RPR FOM that prevent it from working well for space applications. In order to address these deficiencies, the Simulation Interoperability Standards Organization (SISO) developed a new HLA-based interoperability standard to support the needs of complex space systems. This standard is the Space Reference Federation Object Model (SpaceFOM). This paper presents an overview of the SpaceFOM including the fundamentals of the SpaceFOM, the key features of the SpaceFOM, and how the SpaceFOM supports large scale distributed simulation of complex space systems.

SpaceFOM↗
NASA NTRS1983

Data systems - Optical bus will connect distributed system

The fiber optics buses currently under consideration for the NASA space station program will have data rates of at least 20 Mb/sec. The network interconnection scheme that will eventually be used is, however, uncertain. A NASA-Langley effort on graph networks includes adaptive, fault-tolerant and self-correcting operations. A breadboard program at NASA-Johnson includes evaluations of standard devices, called 'bus interface units', in an adaptive and fault-correcting chordal or concentric ring type of network. Fiber optics would allow an evolution to wavelength modulation techniques in such systems.

Swingle, W. L.↗
NASA NTRS1989

Development of Ada language control software for the NASA power management and distribution test bed

The Ada language software developed to control the NASA Lewis Research Center's Power Management and Distribution testbed is described. The testbed is a reduced-scale prototype of the electric power system to be used on space station Freedom. It is designed to develop and test hardware and software for a 20-kHz power distribution system. The distributed, multiprocessor, testbed control system has an easy-to-use operator interface with an understandable English-text format. A simple interface for algorithm writers that uses the same commands as the operator interface is provided, encouraging interactive exploration of the system.

Wright, Ted↗
NASA NTRS1993

The R-Shell approach - Using scheduling agents in complex distributed real-time systems

Large, complex real-time systems such as space and avionics systems are extremely demanding in their scheduling requirements. The current OS design approaches are quite limited in the capabilities they provide for task scheduling. Typically, they simply implement a particular uniprocessor scheduling strategy and do not provide any special support for network scheduling, overload handling, fault tolerance, distributed processing, etc. Our design of the R-Shell real-time environment fcilitates the implementation of a variety of sophisticated but efficient scheduling strategies, including incorporation of all these capabilities. This is accomplished by the use of scheduling agents which reside in the application run-time environment and are responsible for coordinating the scheduling of the application.

Natarajan, Swaminathan↗
NASA NTRSDate not supplied

AEGIS: Autonomous Entity Global Intelligence System for Urban Air Mobility

This paper presents a global intelligence system that synthesizes aerial vehicles’ real-time physical data, planned actions, and historical behavior into engineered data frames representing the collective state of the airspace and suitable for efficient machine learning consumption. These data frames are then learnt by a deep neural net to build a prediction model that estimates the expected evolution path of the current state, thereby identifying potential future conflicts. This approach lends itself to an automated early warning system that the aerial vehicles can implement onboard with a suitable edge computing module more efficiently and effectively than non-AI methods, and eventually take preventive or corrective measures towards self/collaborative resolution of the issues. Contrary to a centralized early warning system where all vehicles’ task-space eventually converges to a global optimum state, the presented distributed global intelligence system brings in a balance between local utility functions of each vehicle and the global operating framework. This contributes to effectively handle the potential massive scaling in urban air mobility in the near future.

Artificial Intelligence↗
NASA NTRS2004

Wireless Communications in Space

In 1992, NASA and the U.S. Department of Defense jointly commissioned the research and development of a technology solution to address the challenges and requirements of communicating with their spacecraft. The project yielded an international consortium composed of representatives from the space science community, industry, and academia. This group of experts developed a broad suite of protocols specifically designed for space-based communications, known today as Space Communications Protocol Standards (SCPS). Having been internationally standardized by the Consultative Committee on Space Data Systems and the International Standards Organization, SCPS is distributed as open source technology by NASA s Jet Propulsion Laboratory (JPL). The protocols are used for every national space mission that takes place today.

Source record↗
NASA NTRS1992

Marshall Space Flight Center's role in the Space Station Freedom program

The Space Station Freedom (S.S. Freedom) is composed of many distributed systems and elements being designed, built, and tested at various United States work centers and international locations. This paper will illustrate the key role of the Marshall Space Flight Center (MSFC) located in Huntsville, Alabama, U.S.A., in support of the S.S. Freedom program.

Abraham, R. N.↗
NASA NTRS1992

A probabilistic fracture mechanics approach for structural reliability assessment of space flight systems

A probabilistic fracture mechanics approach for predicting the failure life distribution due to subcritical crack growth is presented. A state-of-the-art crack propagation method is used in a Monte Carlo simulation to generate a distribution of failure lives. The crack growth failure model expresses failure life as a function of stochastic parameters including environment, loads, material properties, geometry, and model specification errors. A stochastic crack growth rate model that considers the uncertainties due to scatter in the data and mode misspecification is proposed. The rationale for choosing a particular type of probability distribution for each stochastic input parameter and for specifying the distribution parameters is presented. The approach is demonstrated through a probabilistic crack growth failure analysis of a welded tube in the Space Shuttle Main Engine. A discussion of the results from this application of the methodology is given.

Sutharshana, S.↗
NASA NTRS2000

A Future Vision of a Data Acquisition: Distributed Sensing, Processing, and Health Monitoring

This paper presents a vision fo a highly enhanced data acquisition and health monitoring system at NASA Stennis Space Center (SSC) rocket engine test facility. This vision includes the use of advanced processing capabilities in conjunction with highly autonomous distributed sensing and intelligence, to monitor and evaluate the health of data in the context of it's associated process. This method is expected to significantly reduce data acquisitions costs and improve system reliability. A Universal Signal Conditioning Amplifier (USCA) based system, under development at Kennedy Space Center, is being evaluated for adaptation to the SSC testing infrastructure. Kennedy's USCA architecture offers many advantages including flexible and auto-configuring data acquisition with improved calibration and verifiability. Possible enhancements at SSC may include multiplexing the distributed USCAs to reduce per channel cost, and the use of IEEE-485 to Allen-Bradley Control Net Gateways for interfacing with the resident control systems.

Figueroa, Fernando↗
NASA NTRS2000

Advanced Engineering Environments for Space Transportation System Development

There are significant challenges facing today's launch vehicle industry. Global competition, more complex products, geographically-distributed design teams, demands for lower cost, higher reliability and safer vehicles, and the need to incorporate the latest technologies quicker, all face the developer of a space transportation system. Within NASA, multiple technology development and demonstration projects are underway toward the objectives of safe, reliable, and affordable access to space. New information technologies offer promising opportunities to develop advanced engineering environments to meet these challenges. Significant advances in the state-of-the-art of aerospace engineering practice are envisioned in the areas of engineering design and analytical tools, cost and risk tools, collaborative engineering, and high-fidelity simulations early in the development cycle. At the Marshall Space Flight Center, work has begun on development of an advanced engineering environment specifically to support the design, modeling, and analysis of space transportation systems. This paper will give an overview of the challenges of developing space transportation systems in today's environment and subsequently discuss the advanced engineering environment and its anticipated benefits.

Thomas, L. Dale↗
NASA NTRS1987

Critical issues in NASA information systems

The National Aeronautics and Space Administration has developed a globally-distributed complex of earth resources data bases since LANDSAT 1 was launched in 1972. NASA envisages considerable growth in the number, extent, and complexity of such data bases, due to the improvements expected in its remote sensing data rates, and the increasingly multidisciplinary nature of its scientific investigations. Work already has begun on information systems to support multidisciplinary research activities based on data acquired by the space station complex and other space-based and terrestrial sources. In response to a request from NASA's former Associate Administrator for Space Science and Applications, the National Research Council convened a committee in June 1985 to identify the critical issues involving information systems support to space science and applications. The committee has suggested that OSSA address four major information systems issues; centralization of management functions, interoperability of user involvement in the planning and implementation of its programs, and technology.

Source record↗
NASA NTRS1992

Autonomous power system: Integrated scheduling

The Autonomous Power System (APS) project at NASA Lewis Research Center is designed to demonstrate the abilities of integrated intelligent diagnosis, control and scheduling techniques to space power distribution hardware. The project consists of three elements: the Autonomous Power Expert System (APEX) for fault diagnosis, isolation, and recovery (FDIR), the Autonomous Intelligent Power Scheduler (AIPS) to determine system configuration, and power hardware (Brassboard) to simulate a space-based power system. Faults can be introduced into the Brassboard and in turn, be diagnosed and corrected by APEX and AIPS. The Autonomous Intelligent Power Scheduler controls the execution of loads attached to the Brassboard. Each load must be executed in a manner that efficiently utilizes available power and satisfies all load, resource, and temporal constraints. In the case of a fault situation on the Brassboard, AIPS dynamically modifies the existing schedule in order to resume efficient operation conditions. A database is kept of the power demand, temporal modifiers, priority of each load, and the power level of each source. AIPS uses a set of heuristic rules to assign start times and resources to each load based on load and resource constraints. A simple improvement engine based upon these heuristics is also available to improve the schedule efficiency. This paper describes the operation of the Autonomous Intelligent Power Scheduler as a single entity, as well as its integration with APEX and the Brassboard. Future plans are discussed for the growth of the Autonomous Intelligent Power Scheduler.

Ringer, Mark J.↗
NASA NTRS1984

An intelligent robotics control scheme

The problem of robot control is viewed at the level of communicating high-level commands produced by intelligent algorithms to the actuator/sensor controllers. Four topics are considered in the design of an integrated control and communications scheme for an intelligent robotic system: the use of abstraction spaces, hierarchical versus heterarchical control, distributed processing, and the interleaving of the steps of plan creation and plan execution. A scheme is presented for an n-level distributed hierarchical/heterarchical control system that effectively interleaves intelligent planning, execution, and sensory feedback. A three-level version of this scheme has been successfully implemented in the Intelligent Systems Research Lab at NASA Langley Research Center. This implementation forms the control structure for DAISIE (Distributed Artificially Intelligent System for Interacting with the Environment), a testbed system integrating AI software with robotics hardware.

Orlando, N. E.↗