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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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This paper describes the Automated Scheduling and Planning Environment (ASPEN). ASPEN encodes complex spacecraft knowledge of operability constraints, flight rules, spacecraft hardware, science experiments and operations procedures to allow for automated generation of low level spacecraft sequences.
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A backup bar designed to use both vacuum and air pressure provides a method of sealing the weld root of a faulty section of seam weld. With slight redesign, the bar can be made sufficiently flexible to fit any large cylindrical surface.
Electron beam and resistance welding evaluated for application to fabrication of structures in extraterrestrial environment
Application of protective redundancy in digital systems in spacecraft guidance computer and extension to multiprocessing
Experiment designs for collecting human factors engineering data on advanced space systems maintenance
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STAR computer has five redundant modular function units, fixed store, arithmetic, memory, input, and output. Each unit is connected to a diagnostic control unit, each is coded for error detection and error correction. Separation into function units permits assembly of many different systems from the set of units.
Evaluating toxicity of propellant within space station, leakage criteria of propellant and nitrogen, and weight comparisons of five candidate resupply systems - graphs
Design and reliability of digital systems for hard cores of fault tolerant computers /hybrid- redundant systems/, discussing advantages over multiplexed systems
Mammalian tissues metabolic and genetic alteration during weightlessness, relating rats liver regeneration delay to centrifuging intensity following hepatectomy
Successful planetary exploration missions have been completed by unmanned Mariner spacecraft, which were designed at the Jet Propulsion Laboratory. Mariner II completed a 109-day flyby mission to Venus on December 14, 1962. This mission was followed by the flyby of Mars and return of 21 historic photographs of its surface by Mariner IV in July 1965. Further successful missions followed: Mariner V to Venus in 1967, Mariners VI and VII to Mars in 1969. In all of these missions, a Central Computer and Sequencer onboard the spacecraft was used to provide on-board control functions, although complete ground backup was also available.
This paper presents the results obtained in a continuing investigation of fault-tolerant computing which is being conducted at the Jet Propulsion Laboratory. Initial studies led to the decision to design and construct an experimental computer with dynamic (standby) redundancy, including replaceable subsystems and a program rollback provision to eliminate transient errors. This system, called the STAR computer, began operation in 1969. The following aspects of the STAR system are described: architecture, reliability analysis, software, automatic maintenance of peripheral systems, and adaptation to serve as the central computer of an outer-planet exploration spacecraft.
A summary is presented of various methods available to the engineer for dealing with fatigue problems. Design, metallurgical, and service factors are considered. An attempt is made to provide a rational basis for each approach, resorting in each case to an understanding of the fundamental mechanism of the fatigue process.
New forming and patching methods have been developed for high-quality graphite/epoxy laminates. Laminates range in thickness from 0.012 to 0.018 in. (0.31 to 0.46 mm).
Refill/leveling technique, which consists of spreading slurry refill material to affected areas and then sanding until surfaces are flat, extends service life of platen up to 50 production cycles between downtime.
A method was developed for the construction of probabilistic state-space models for nonrepairable systems. Models were developed for several systems which achieved reliability improvement by means of error-coding, modularized sparing, massive replication and other fault-tolerant techniques. From the models developed, sets of reliability and coverage equations for the systems were developed. Comparative analyses of the systems were performed using these equation sets. In addition, the effects of varying subunit reliabilities on system reliability and coverage were described. The results of these analyses indicated that a significant gain in system reliability may be achieved by use of combinations of modularized sparing, error coding, and software error control. For sufficiently reliable system subunits, this gain may far exceed the reliability gain achieved by use of massive replication techniques, yet result in a considerable saving in system cost.