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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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NASA NTRS2000

EVA Design, Verification, and On-Orbit Operations Support Using Worksite Analysis

The International Space Station (ISS) design is a very large and complex orbiting structure with thousands of Extravehicular Activity (EVA) worksites. These worksites are used to assemble and maintain the ISS. The challenge facing EVA designers was how to design, verify, and operationally support such a large number of worksites within cost and schedule. This has been solved through the practical use of computer aided design (CAD) graphical techniques that have been developed and used with a high degree of success over the past decade. The EVA design process allows analysts to work concurrently with hardware designers so that EVA equipment can be incorporated and structures configured to allow for EVA access and manipulation. Compliance with EVA requirements is strictly enforced during the design process. These techniques and procedures, coupled with neutral buoyancy underwater testing, have proven most valuable in the development, verification, and on-orbit support of planned or contingency EVA worksites.

Hagale, Thomas J.↗
NASA NTRS2001

Platform-Independence and Scheduling In a Multi-Threaded Real-Time Simulation

Aviation research often relies on real-time, pilot-in-the-loop flight simulation as a means to develop new flight software, flight hardware, or pilot procedures. Often these simulations become so complex that a single processor is incapable of performing the necessary computations within a fixed time-step. Threads are an elegant means to distribute the computational work-load when running on a symmetric multi-processor machine. However, programming with threads often requires operating system specific calls that reduce code portability and maintainability. While a multi-threaded simulation allows a significant increase in the simulation complexity, it also increases the workload of a simulation operator by requiring that the operator determine which models run on which thread. To address these concerns an object-oriented design was implemented in the NASA Langley Standard Real-Time Simulation in C++ (LaSRS++) application framework. The design provides a portable and maintainable means to use threads and also provides a mechanism to automatically load balance the simulation models.

Sugden, Paul P.↗
NASA NTRS1991

Onboard navigation rendezvous expert system

The Onboard Navigation rendezvous expert system is designed to aid the ground flight controller in monitoring the shuttle onboard navigation system. The system is designed to keep track of the navigation sensors and relative state vectors. In addition, the system also keeps an event log and fills out forms usually handled by the flight controller. This expert system is one of the few rendezvous specific systems being developed for the Mission Control Center. The expert system has been in development for six years. Through these years the system has seen hardware, software, and personnel changes. Initial development was done by the Information Systems Directorate (ISD) and Mission Operations Directorate (MOD) at Johnson Space Center. As of October 1, 1991 the system has been turned over to MOD. The system is completely developed except for some minor adjustments to the user interface. The rule base is in the verification stage with total certification of the system due to be completed by May 1992. Test cases for verification are obtained by saving data used for flight controller integrated simulations. The actual data comes from both the shuttle mission simulator and the Mission Control Center Computer. So far no actual flight data has been available. This paper covers all aspects of the system from the development history to the current hardware, software, and use of the system.

Kocen, Michelle↗
NASA NTRS1996

Solid Surface Combustion Experiment Completes a Series of Eight Successful Flights

The Solid Surface Combustion Experiment (SSCE) was the first combustion experiment to fly in the space shuttle and the first such experiment in the NASA spaceflight program since Skylab. SSCE was actually a series of experiments designed to begin to characterize flame spreading over solid fuels in microgravity and the differences of this flame spreading from normal gravity behavior. These experiments should lead to a better understanding of the physical processes involved--increasing our understanding of fire behavior, both in space and on Earth. SSCE results will help researchers evaluate spacecraft fire hazards. These experiments were conceived by the principal investigator, Professor Robert A. Altenkirch, Dean of Engineering at Washington State University. In the first five flights, the fuel sample--ashless filter paper instrumented with three thermocouples--was mounted in a sealed chamber filled with a 50-percent or 35-percent mixture of oxygen in nitrogen at pressures of 1.0, 1.5, and 2.0 atm. In the next three flights, a polymethyl methacrylate (plexiglass) fuel was instrumented with three thermocouples and tested in a 70-percent or 50-percent mixture of oxygen and nitrogen at pressures of 1.0 and 2.0 atm. SSCE is a self-contained, battery-operated experiment that can be flown either in the shuttle middeck or in the Spacelab module. More information about the hardware configuration have been published. This past year, the final two of eight flights were completed on STS-64 and STS-63. The NASA Lewis Research Center designed and built the SSCE payload and performed engineering, testing, scientific, and flight operations support. The SSCE project was supported in some way by nearly every major sector of Lewis' organization. Professor Altenkirch developed a numerical simulation of the flame-spreading process from first principles (of fluid mechanics, heat transfer, and reaction kinetics). The spread rates, flame shape, and thermodynamic data from the SSCE flights are being compared directly with the results of the computational model. Results from the eight flights will be used to formulate an improved solid-phase pyrolysis model. In addition, some results of the flights have been published and presented at international combustion symposiums. Additional solid fuel combustion experiments are being investigated for future tests with the existing hardware.

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NASA NTRS1971

Space shuttle low cost/risk avionics study

All work breakdown structure elements containing any avionics related effort were examined for pricing the life cycle costs. The analytical, testing, and integration efforts are included for the basic onboard avionics and electrical power systems. The design and procurement of special test equipment and maintenance and repair equipment are considered. Program management associated with these efforts is described. Flight test spares and labor and materials associated with the operations and maintenance of the avionics systems throughout the horizontal flight test are examined. It was determined that cost savings can be achieved by using existing hardware, maximizing orbiter-booster commonality, specifying new equipments to MIL quality standards, basing redundancy on cost effective analysis, minimizing software complexity and reducing cross strapping and computer-managed functions, utilizing compilers and floating point computers, and evolving the design as dictated by the horizontal flight test schedules.

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NASA NTRS1971

Analysis of parallel systems.

A formal analysis procedure for hardware and software computer systems is described. A system is described by a flow table model. The concept of an output hazard is introduced to account for effects of unbounded line delays. Necessary and sufficient conditions for the absence of output hazards are given. A system that contains no output hazards is said to operate correctly if the system state graph that describes all system states and state transitions is free from forbidden states and forbidden state sequences. A flow table solution for the two-component mutual exclusion problem is analyzed and shown to be correct.

Bredt, T. H.↗
NASA NTRS1992

Functional requirements document for NASA/MSFC Earth Science and Applications Division: Data and information system (ESAD-DIS). Interoperability, 1992

These Earth Science and Applications Division-Data and Information System (ESAD-DIS) interoperability requirements are designed to quantify the Earth Science and Application Division's hardware and software requirements in terms of communications between personal and visualization workstation, and mainframe computers. The electronic mail requirements and local area network (LAN) requirements are addressed. These interoperability requirements are top-level requirements framed around defining the existing ESAD-DIS interoperability and projecting known near-term requirements for both operational support and for management planning. Detailed requirements will be submitted on a case-by-case basis. This document is also intended as an overview of ESAD-DIs interoperability for new-comers and management not familiar with these activities. It is intended as background documentation to support requests for resources and support requirements.

Stephens, J. Briscoe↗
NASA NTRS1993

Interferometric tracking system for the tracking and data relay satellite

This report documents construction and testing of the Interferometric Tracking System project developed under the NASA SBIR contract NAS5-30313. Manuals describing the software and hardware, respectively entitled: 'Field Station Guide to Operations' and 'Field Station Hardware Manual' are included as part of this final report. The objective of this contract was to design, build, and operate a system of three ground stations using Very Long Baseline Interferometry techniques to measure the TDRS orbit. The ground stations receive signals from normal satellite traffic, store these signals in co-located computers, and transmit the information via phone lines to a central processing site which correlates the signals to determine relative time delays. Measurements from another satellite besides TDRS are used to determine clock offsets. A series of such measurements will ultimately be employed to derive the orbital parameters, yielding positions accurate to within 50 meters or possibly better.

Effland, John E.↗
NASA NTRS1993

Real-time expert system diagnostics and monitoring for the High Resolution Microwave Survey Targeted Search

An automated monitoring and diagnostics system (MDS) using virtual real-time software was developed for NASA's High Resolution Microwave Survey (HRMS) Targeted Search System (TSS). The four main tasks required of the MDS were monitoring and recording system health, alerting operators of problems, diagnosing poor system performance, and performing an emergency system shutdown. The MDS was implemented using commercial expert system software tools in addition to interface hardware and software developed on site. The expert system used objects, rules, and schematics in its TSS knowledge representation. The MDS was successfully integrated into the HRMS computer environment, and its performance met or exceeded its requirements.

Macalou, A.↗
NASA NTRS2021

Assessing Relay Communications for Mars Sample Return Surface Mission Concepts

The Mars Sample Return (MSR) Campaign would be a 3-mission campaign concept supported by NASA and ESA to return samples from the Mars surface. MSR would, for the first time ever, present a need to communicate with multiple surface assets that are co-located on Mars in a coordinated effort to accomplish the unified objective of fetching, transporting, and returning samples from Mars. Currently, Mars surface assets relay data to and from Earth using a number of orbiters in what’s known as the Mars Relay Network (MRN). This network is characterized by a small number of surface assets distributed across the Martian globe and a larger number of orbiters to provide relay services. As of June 2020, there are two surface assets for which five orbiters are providing relay. During the MSR Campaign, there would be two rovers and a lander that all would require relay communication from a small number of Mars orbiters to meet the aggressive MSR timeline. The inversion of the current MRN paradigm, a system of many surface assets requiring relay and few orbiters to provide relay, necessitates the unique challenge of optimally allocating relay passes to maximize the operational capability of all assets. The allocation must consider a large number of trade variables including Mars asset operational requirements and Earth ground system constraints, including staffing schedules, operations planning across time zones, and more. To address these telecommunication challenges, the Mars Asset Relay Mission Link Allocation Design Environment (MARMLADE) tool was developed. It is a MATLAB-based tool to assign orbiter passes or Direct-From-Earth (DFE) links to each of the three surface assets and quantify the operational efficiency of each surface asset.MARMLADE uses a data set of simulated Mars relay orbiter geometry and telecommunication capabilities provided by JPL’s Telecom Orbit Analysis and Simulation Tool (TOAST) software to compute which asset should get each pass based on a series of heuristics and predictions of all assets’ states. Within MARMLADE, the user can provide inputs including the option for time-based pass splitting, fixed FWD data rate capabilities, DFE communication capabilities, and link parameters allowing for the assessment of complex operations and hardware trades using surface mission operational efficiency as a primary figure of merit. As the MSR mission concepts continue to mature, MARMLADE is being used to assess ability of all MSR elements to meet the surface mission timeline requirements and to provide relay link allocations to each of the MSR surface assets.This paper will describe the motivation and design of the MARMLADE tool and how it is being used to perform campaign and mission level trades, generate requirements, and support development of the MSR surface mission scenarios.

Lee, Charles↗
NASA NTRS1972

Guidance system operations plan for manned CM earth orbital missions using program Skylark 1. Section 2: Data links

A computer program to define the digital uplink and downlink for use in manned command module orbital missions is presented. The subjects discussed are: (1) digital uplink to command module, (2) CMC digital downlink, (3) downlist formats, (4) description of telemetered qualities, (5) flagbits, and (6) effects of Fresh Start (V36) and Hardware Restart on flagword and channel bits.

Hamilton, M. H.↗
NASA NTRS1971

Mariner-Venus 1967

Detailed information on the spacecraft performance, mission operations, and tracking and data acquisition is presented for the Mariner Venus 1967 and Mariner Venus 1967 extension projects. Scientific and engineering results and conclusions are discussed, and include the scientific mission, encounter with Venus, observations near Earth, and cruise phase of the mission. Flight path analysis, spacecraft subsystems, and mission-related hardware and computer program development are covered. The scientific experiments carried by Mariner 5 were ultraviolet photometer, solar plasma probe, helium magnetometer, trapped radiation detector, S-band radio occultation, dual-frequency radio propagation, and celestial mechanics. The engineering experience gained by converting a space Mariner Mars 1964 spacecraft into one flown to Venus is also described.

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NASA NTRS1975

Data management for Large Space Telescope

The data management system for the Large Space Telescope (LST) must be capable of meeting requirements of 160 million bits per 95 min orbit with a bit error rate of less than 0.00001 for data. The system will be supported by the Tracking and Data Relay Satellite System of the Space Tracking and Data Network. The on-board system includes a general purpose computer that controls the vehicle as a stable observation platform and the array of instruments used for data collection. The ground-based system comprises a Mission Operations Center (MOC), a Science Institute where instrument data is processed, and a communications service for the space and point-to-point data flow. The allocation of hardware and software between on-board and ground-based components to achieve design objectives of maximum flexibility at minimum cost is discussed.

Hope, G. R., Jr.↗
NASA NTRS1982

Cost effective development of a Shuttle-based astronomical instrument control system

The high level language FORTH is used for the electronic control of the Space Shuttle-based Ultraviolet Imaging Telescope, in a flight computer system which minimizes costs. The greater part of the breadboard version of the flight computer is assembled from commercially available components, reducing novel circuit design features and permitting simultaneous development of both hardware and software. The commercial boards are then refabricated on aluminum core heat conducting stock, using high reliability parts to produce the flight versions of the system. The system's ground support equipment employs a MINC-25 minicomputer which performs such functions as flight computer software development, PROM programming, test and integration support, and flight operations support. The implementation of these concepts in flight computer telescope controls is described.

Parise, R. A.↗
NASA NTRS1985

SSME failure detection

During ground testing of the Space Shuttle Main Engine (SSME), there have been twenty-six major incidents resulting in substantial hardware damage and loss. Historical characteristics, advances in detection technology, and advances in computing technology led to plans for study of an advanced real time SSME test stand failure detection system which would reduce damage and preserve evidence when a failure with major incident potential occurs. This detection system will speed recognition of dangerous engine operation, and quicken the shutdown decision. The scope of this study, SSME characteristics, SSME test history, the problem definition, and some technical issues will be addressed herein.

Cikanek, H. A., III↗
NASA NTRS1989

A methodology for validating software reliability

A significant problem associated with fault tolerant computer system design is how to insure that there are no embedded software errors, so that an avionics computer system meets the required reliability level. To accomplish this, it is necessary to associate a 'probability of failure' with the operational flight program. It would be more correct to say that the probability of excitation of existing latent design errors within the program is required. In this sense, latent software errors are like latent hardware faults, and techniques that were previously used to measure the probability of failure of hardware due to fault latency can be used to measure the probability of failure of the software. A methodology was developed and applied to a flight control program that was known to operate in a well defined environment. The results indicated that the technique could be used to provide a final validation of the software to a specified reliability level and to evaluate the role of flight test in software validation.

Swern, Frederic L.↗
NASA NTRS1976

A Remotely Operated Multiple Array Acoustic Range (ROMAAR) and its application for the measurement of airplane flyover noise footprints

The ROMAAR now in operation at NASA will allow direct measurement and display of aircraft noise in several measurement units during takeoff, landing, and flyby operations. This information, in addition to its application in terms of ground noise footprints, will also permit determination of the statistical variation of footprints or contours due to the atmosphere or aircraft operational parameters, and a measure of the impact of various noise reduction techniques and hardware on ground noise footprints. The methods, techniques, and equipment developed for the ROMAAR concept are applicable to CTOL, STOL, General Aviation, and VTOL aircraft. ROMAAR represents a unique combination of state of the art digital and analog noise recording methods, computer-controlled digital communications methods, radar-tracking facilities, quick-look weather capabilities, and a large data handling facility complemented by a large capacity curve fitting and plotting routine. The ROMAAR is set apart from the standard airport noise monitoring system by having the unique features mentioned above plus the fact that at present as many as 38 separate (but simultaneous) noise measurements can be made for each aircraft overflight.

Hilton, D. A.↗
NASA NTRS1981

Selecting an image analysis minicomputer system

Factors to be weighed when selecting a minicomputer system as the basis for an image analysis computer facility vary depending on whether the user organization procures a new computer or selects an existing facility to serve as an image analysis host. Some conditions not directly related to hardware or software should be considered such as the flexibility of the computer center staff, their encouragement of innovation, and the availability of the host processor to a broad spectrum of potential user organizations. Particular attention must be given to: image analysis software capability; the facilities of a potential host installation; the central processing unit; the operating system and languages; main memory; disk storage; tape drives; hardcopy output; and other peripherals. The operational environment, accessibility; resource limitations; and operational supports are important. Charges made for program execution and data storage must also be examined.

Danielson, R.↗