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Material acquisition fundamentals were reviewed and include: mission profile definition, stress analysis, derating criteria, circuit reliability, failure modes, and worst case analysis. Military system reliability was examined with emphasis on the sparing of equipment. The Navy's organizational strategy for 1980 is presented.
Normal rates of dentinogenesis and osteogenesis in the body of the mandible were observed. The total calcium, inorganic phosphorus and hydroxyproline levels in the jaws and incisors of the flight rats were normal. Gravity density fractionation studies suggested, however, that spaceflight caused a delay in the normal maturation of bone mineral and matrix; normal values were reestablished by 6 days postflight. The teeth were spared. The circadian and ultradian patterns of dentin calcification were normal during spaceflight and recovery periods, but the enamel rhythms displayed a greater amplitude of sulfur concentrations and this abnormal calcium to sulfur ratios only during exposure to zero gravity. The rat mandible and teeth do not suffer the deficits of bone formation common to weight bearing parts of the skeleton during spaceflight. The only derangements detected were in the quality of the matrix and mineral moieties.
A methodology for the design of a tightly coupled, highly reliable microprocessor based computer system is described. The concept of triple modular redundancy with sparing is used. The notion of synchronizing by using a single crystal oscillator is examined. The use of decoders to replace voters is also used. The decoders not only isolate the failed module but also allow error identification to be accomplished. Each module is to have its own RAM memory. The necessary circuitry to select a correct memory and the corresponding DMA controller was designed.
The planned space shuttle mission STS-4 will use the Skylab flight spare ten-color (near UV to near IR) photopolarimeter with boresighted 16 mm camera. This 164-hour mission will observe the zodiacal light to within approximately 20 deg of the sun (in and out of the ecliptic). The mission consists of several distinct phases: (1) tail-to-sun (TTS), belly to earth for 18 hours; (2) nose-to-sun, solar inertial for 79 hours; (3) bay-to-sun for 26 hours; and (4) passive thermal control for 37 hours. During the TTS phase, where most observations are scheduled, the instrument will scan back and forth in elevation at 4 deg/sec while the orbiter moves across the sky at its 4 deg/min orbital rate. The combined orbiter/instrument motion will result in a saw-tooth pattern of observations projected on the sky (between the 14 deg and 120 deg elevation limits) and will enable extensive measurements of the brightness, polarization and color of the background starlight to be made.
The process of preparation for the first two shuttle flights was observed and information from both flights was gathered in order to confirm the concept and performance of the major elements of the space transportation system. To achieve truly operational operating safety, regularity, and minimum practical cost, the organization of efforts between the R&D community and any transportation service organization should be clearly separated with the latter organization assuming responsibilities for marketing its services; planning and acquiring prime hardware and spares; maintainance; certification of procedures; training; and creation of requirements for future development. A technical audit of the application of redundancy concepts to shuttle systems is suggested. The state of the art of space transportation hardware suggests that a number of concept changes may improve reliability, costs, and operational safety. For the remaining R&D flights, it is suggested that a redline audit be made of limits that should not be exceeded for ready to launch.
The TIGER algorithm, the inputs to the program and the output are described. TIGER is a computer program designed to simulate a system over a period of time to evaluate system reliability and availability. Results can be used in the Deep Space Network for initial spares provisioning and system evaluation.
The forecast is for the years 1981 - 2000 with benchmark years at 1985, 1990 and 2000. Two typs of markets are considered for this study: Hardware (worldwide total) - satellites, earth stations and control facilities (includes replacements and spares); and non-hardware (addressable by U.S. industry) - planning, launch, turnkey systems and operations. These markets were examined for the INTELSAT System (international systems and domestic and regional systems using leased transponders) and domestic and regional systems. Forecasts were determined for six worldwide regions encompassing 185 countries using actual costs for existing equipment and engineering estimates of costs for advanced systems. Most likely (conservative growth rate estimates) and optimistic (mid range growth rate estimates) scenarios were employed for arriving at the forecasts which are presented in constant 1980 U.S. dollars. The worldwide satellite market demand forecast predicts that the market between 181 and 2000 will range from $35 to $50 billion. Approximately one-half of the world market, $16 to $20 billion, will be generated in the United States.
The multiplexer-demultiplexer (MDM) project included the design, documentation, manufacture, and testing of three MDM Data Systems. The equipment is contained in 59 racks, and includes more than 3,000 circuit boards and 600 microprocessors. Spares, circuit card testers, a master set of programmable integrated circuits, and a program development system were included as deliverables. All three MDM's were installed, and were operationally tested. The systems performed well with no major problems. The progress and problems analysis, addresses schedule conformance, new technology, items awaiting government approval, and project conclusions are summarized. All contract modifications are described.
The rate of solution of a stationary bubble is limited by the diffusion of dissolved gas molecules away from the bubble surface. Diffusion coefficients computed from measured rates of solution give mean values higher than accepted literature values, with standard errors as high as 10% for a single observation. Better accuracy is achieved with sparingly soluble gases, small bubbles, and highly viscous liquids. Accuracy correlates with the Grashof number, indicating that free convection is the major source of error. Accuracy should, therefore, be greatly increased in a gravity-free environment. The fact that the bubble will need no support is an additional important advantage of Spacelab for this measurement.
The Dynamics Explorer Langmuir probe instrument (DE-LANG), a spare unit from the Pioneer Venus mission that has been modified to work with the DE spacecraft, is described. Two independent sensors are connected to individual adaptive sweep voltage circuits that continuously track the changing electron temperature and spacecraft potential while autoranging electrometers adjust their gain in response to the changing plasma density. The control signals used in achieving this automatic tracking provide a continuous monitor of the ionospheric parameters without telemetering each volt-ampere curve. In addition, internal data storage circuits permit high-resolution, high-data-rate sampling of selected volt-ampere curves for transmission to the ground to verify or correct the inflight processed data.
NASA near-earth orbit tracking and data acquisition activities are evolving from a network of ground tracking stations located in the U.S. and around the world, to a network of two, in synchronous orbit, tracking and data relay satellites plus an in orbit spare. This paper discusses the elements that make up this evolving Tracking and Data Relay Satellite System (TDRSS) Network, that will provide the basis for the tracking and data relay satellite (TDRS) operations in the 1980's.
Long-term adaptation mechanisms to maintain homeostasis at increased levels of exertion such as those caused by regular exercise are described. Mitochondrial changes have been found to be a result of endurance exercises, while mitochondrial responses to other types of exercise are small. Further discussion is devoted to long-term changes in glucose transport, hexokinase, phosphofructokinase, pyruvate kinase, and the increased sensitivity of an endurance trained muscle to insulin. Less lactate has been found to be produced by the skeletal muscles at the same work rate after adaptation to endurance exercise training, and the capacity for the flux of the two-carbon acetyl chain through the citric acid cycle increases in skeletal muscles in response to endurance training. Finally, endurance training is noted to result in glycogen sparing and an increase in the capacity to utilize fatty acids.
The handling and positioning aid which (HPA) provides a wide range of adjustable work stations both inboard and outboard of the cargo bay is discussed. It can assist with berthing and docking, it is robust, stiff, has a simple control system, and is modular. An articulated arm version of HPA employed in a typical servicing mission is shown. Mounted on a base frame that spans the Orbiter cargo bay, the 6 m arm is long enough to hold the satellite being serviced and keep its solar array clear of the Orbiter radiators. By adjusting the length and angle of the support platform mast, and rotating the tip of the HPA arm, almost every item on the satellite can be reached. Spares and change-out units can be brought to and from the work site by the RMS, which is controlled from the aft flight deck. The fore and aft position of the base frame can be changed between Orbiter flights and this, together with the 5 degrees of freedom (DOF) of the long arm, allows work sites to be chosen that meet the clearance, reach and vision requirements of many missions. Flight article activities are shown are shown above the dashed horizontal line and Development Test Article (DTA) work below. Flight article requirements and concepts and the design of the DTA are developed.
A fly by wire flight control system architecture designed for high reliability includes spare sensor and computer elements to permit safe dispatch with failed elements, thereby reducing unscheduled maintenance. A methodology capable of demonstrating that the architecture does achieve the predicted performance characteristics consists of a hierarchy of activities ranging from analytical calculations of system reliability and formal methods of software verification to iron bird testing followed by flight evaluation. Interfacing this architecture to the Lockheed S-3A aircraft for flight test is discussed. This testbed vehicle can be expanded to support flight experiments in advanced aerodynamics, electromechanical actuators, secondary power systems, flight management, new displays, and air traffic control concepts.
The Space Operations Center (SOC) is conceived as a permanent facility in low Earth orbit incorporating capabilities for space systems construction; space vehicle assembly, launching, recovery and servicing; and the servicing of co-orbiting satellites. The Shuttle Transportation System is an integral element of the SOC concept. It will transport the various elements of the SOC into space and support the assembly operation. Subsequently, it will regularly service the SOC with crew rotations, crew supplies, construction materials, construction equipment and components, space vehicle elements, and propellants and spare parts. The implications to the SOC as a consequence of the Shuttle supporting operations are analyzed. Programmatic influences associated with propellant deliveries, spacecraft servicing, and total shuttle flight operations are addressed.
Kennedy Space Center's primary institutional computer is a 4 megabyte IBM 4341 with 3.175 billion characters of IBM 3350 disc storage. This system utilizes the Software AG product known as ADABAS with the on line user oriented features of NATURAL and COMPLETE as a Data Base Management System (DBMS). It is operational under the OS/VSI and is currently supporting batch/on line applications such as Personnel, Training, Physical Space Management, Procurement, Office Equipment Maintenance, and Equipment Visibility. A third and by far the largest DBMS application is known as the Shuttle Inventory Management System (SIMS) which is operational on a Honeywell 6660 (dedicated) computer system utilizing Honeywell Integrated Data Storage I (IDSI) as the DBMS. The SIMS application is designed to provide central supply system acquisition, inventory control, receipt, storage, and issue of spares, supplies, and materials.
A comparison of the sensitivity and intrusion of twenty pilot workload assessment techniques was conducted using a psychomotor loading task in a three degree of freedom moving base aircraft simulator. The twenty techniques included opinion measures, spare mental capacity measures, physiological measures, eye behavior measures, and primary task performance measures. The primary task was an instrument landing system (ILS) approach and landing. All measures were recorded between the outer marker and the middle marker on the approach. Three levels (low, medium, and high) of psychomotor load were obtained by the combined manipulation of windgust disturbance level and simulated aircraft pitch stability. Six instrument rated pilots participated in four seasons lasting approximately three hours each.
The operational experience obtained for the GT404-4 gas turbine engines in the intercity and intracity Bus Demonstration Programs is described for the period January 1980 through September 1981. Support for the engines and automatic transmissions involved in this program provided engineering and field service, spare parts and tools, training, and factory overhauls. the Greyhound (intercity) coaches accumulated 183,054 mi (294,595 km) and 5154 hr of total operation. The Baltimore Transit (intracity) coaches accumulated 40,567 mi (65,285 km) and 1840 hr of total operation. In service, the turbine powered Greyhound and Transit coaches achieved approximately 25% and 40% lower fuel mileage, respectively, than did the production diesel powered coaches. The gas turbine engine will require the advanced ceramic development currently being sponsored by the DOE and NASA to achieve fuel economy equivalent not only to that of today's diesel engines but also to the projected fuel economy of the advanced diesel engines of the 1990s. Sufficient experience was not achieved with the coaches prior to the start of service to identify and eliminate many of the problems associated with the startup of new equipment. Because of these problems, the mean miles between incident were unacceptably low. The future gas turbine system should be developed sufficiently to establish satisfactory durability prior to evaluation in revenue service. Commercialization of the gas turbine bus engine remains a viable goal for the future.