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Portions of the LANDSAT-D systems operation plan are presented. An overview of the data processing operations, logistics and other operations support, prelaunch and post-launch activities, thematic mapper operations during the scrounge period, and LANDSAT-D performance evaluation is given.
This paper describes the Pacific Basin Communications Study, an assessment of Pacific islands telecommunications requirements, recently completed by the Public Service Satellite Consortium under contract with the National Aeronautics and Space Administration (NASA). The study describes extant and planned telecommunications systems in the region, examines user needs in terms of the development of governmental, social and commercial activities, and proposes and describes alternative technological solutions to communications problems. Questions of financing, implementation, management, costs and benefits of a regional telecommunications system are discussed. This paper describes user requirements based on six months of field investigation and technological options for improving telecommunications in the Pacific islands.
The present investigation takes into account the published literature on outer planet satellites for 1979-1982. It is pointed out that all but three (the moon and the two Martian satellites) of the known planetary satellites are found in the outer solar system. Most of these are associated with the three regular satellite systems of Jupiter, Saturn, and Uranus. The largest satellites are Titan in the Saturn system and Ganymede and Callisto in the Jupiter system. Intermediate in size between Mercury and Mars, each has a diameter of about 5000 km. Presumably each has an internal composition about 60 percent rock and 40 ice, and each is differentiated with a dense core extending out about 75 percent of the distance to the surface, with a mantle of high-pressure ice and a crust of ordinary ice perhaps 100 km thick. Attention is also given to Io, Europa, the icy satellites of Saturn, the satellites of Uranus, the small satellites of Jupiter and Saturn, Triton and the Pluto system, and plans for future studies.
With the emergence of a new era in satellite communications brought about by NASA's thrust into the Ka band with multibeam and onboard processing technologies, new and innovative techniques for evaluating these concepts and systems are required. To this end, NASA, in conjunction with its extensive program for advanced communications technology development, has undertaken to develop a concept for the simulation and evaluation of a complete communications network. Incorporated in this network will be proof of concept models of the latest technologies proposed for future satellite communications systems. These include low noise receivers, matrix switches, baseband processors, and solid state and tube type high power amplifiers. To accomplish this, numerous supporting technologies must be added to those aforementioned proof of concept models. These include controllers for synchronization, order wire, and resource allocation, gain compensation, signal leveling, power augmentation, and rain fade and range delay simulation. Taken together, these will be assembled to comprise a system capable of addressing numerous design and performance questions. The simulation and evaluation system as planned will be modular in design and implementation, capable of modification and updating to track and evaluate a continuum emerging concepts and technologies.
With the emergence of a new era in satellite communications, brought about by NASA's thrust into the Ka band with multibeam and onboard processing technologies, new and innovative techniques for evaluating these concepts and systems are required. To this end, NASA, in conjunction with its extensive program for advanced communications technology development, has undertaken to develop a concept for the simulation and evaluation of a complete communications network. Incorporated in this network will be proof-of-concept models of the latest technologies proposed for future satellite communications systems. These include low noise receivers, matrix switches, baseband processors, and solid state and tube type high power amplifiers. To accomplish this, numerous supporting technologies must be added to those aforementioned proof-of-concept models. These include controllers for synchronization, order wire, resource allocation, gain compensation, signal leveling, power augmentation, and rain fade and range delay simulation. Taken together, these will be assembled to comprise a system capable of addressing numerous design and performance questions. The simulation and evaluation system, as planned, will be modular in design and implementation, capable of modification and updating to track and evaluate a continuum of emerging concepts and technologies. Previously announced in STAR as N84-13400
The first priority of the NSTS program is to make the Space Shuttle system fully operational and cost effective in providing routine access to space. In support of this priority an integrated logistics support system was planned, structured and is being implemented to support a launch-on-time goal of 95 percent. In achieving a 95 percent spares 'fill rate' in an environment of small fleet size, highly unique and high cost assets, significant spares cost can be incurred. A major portion of these costs are for the additional spares required when repair or acquisition times are lengthy. This paper provides a fundamental analysis of the costs and other factors involved in the spare and repair process and provides an optimized cost and process solution for the Space Shuttle program - a centralized repair depot located at KSC.
An integrated logistics support system, which would provide routine access to space and be cost-competitive as an operational space transportation system, was planned and implemented to support the NSTS program launch-on-time goal of 95 percent. A decision was made to centralize the Shuttle logistics functions in a modern facility that would provide office and training space and an efficient warehouse area. In this warehouse, the emphasis is on automation of the storage and retrieval function, while utilizing state-of-the-art warehousing and inventory management technology. This consolidation, together with the automation capabilities being provided, will allow for more effective utilization of personnel and improved responsiveness. In addition, this facility will be the prime support for the fully integrated logistics support of the operations era NSTS and reduce the program's management, procurement, transportation, and supply costs in the operations era.
The results of three separate investigations performed by Science Applications International Corporation (SAIC) between August 1985 and October 1986 as the second phase of the two-phase Satellite Services System Program Plan contract for the Engineering Directorate of the Lyndon B. Johnson Space Center are discussed. The objectives of the first phase of this contract (reported in SAIC-85/1762) were to determine the potential for servicing a diverse range of spacecraft from the Space Shuttle Orbiter and to assess NASA's role as the catalyst in enabling routine on-orbit servicing. The second area of investigation was prompted by the need to understand satellite servicing requirements in the far term (1995 to 2010) and how results from the first phase of this contract could support these requirements. The mission model developed during the first phase was extended using new data and information from studies which address the later time period. The third area of investigation looked at a new servicing mode which had not been studied previously. This mode involves the on-orbit exchange of very large modules with masses greater than approximately 9,000 kilograms and/or lengths greater than approximately nine meters. The viewgraphs used for the final briefing for each of the three investigations, as presented to NASA are given.
Instrumentation presently being developed by NASA for the collection and analysis of organic gases and aerosols in Titan's atmosphere is described together with the results of the preliminary experiments. For the aerosols, stepwise pyrolysis was shown to be a suitable method for preparing complex organic material for gas chromatography (GC), and a pyrolysis-gas chromatograph was developed and successfully used to analyze a simulated Titan aerosol. Atmospheric gases will be collected by a low-pressure gas sampling system using large-volume sample loops and analyzed by GC. The results of preliminary studies using a 20 cu cm sampling system and a very sensitive metastable ionization detector showed that hydrocarbon components at the 10 ppb level can be detected. Studies are in progress on shortening the overall analysis time by improving the pyrolysis system, the gas sampling system, and the associated gas chromatograph. Further development of the gas sampling system is planned to ensure rapid collection of samples adequate for analysis by GC over the entire range of pressures to be encountered during the probe's descent.
The Data Management System network is a complex and important part of manned space platforms. Its efficient operation is vital to crew, subsystems and experiments. AI is being considered to aid in the initial design of the network and to augment the management of its operation. The Intelligent Resource Management for Local Area Networks (IRMA-LAN) project is concerned with the application of AI techniques to network configuration and management. A network simulation was constructed employing real time process scheduling for realistic loads, and utilizing the IEEE 802.4 token passing scheme. This simulation is an integral part of the construction of the IRMA-LAN system. From it, a causal model is being constructed for use in prediction and deep reasoning about the system configuration. An AI network design advisor is being added to help in the design of an efficient network. The AI portion of the system is planned to evolve into a dynamic network management aid. The approach, the integrated simulation, project evolution, and some initial results are described.
A hierarchical functional autonomous controller architecture is introduced. In particular, the architecture for the control of future space vehicles is described in detail; it is designed to ensure the autonomous operation of the control system and it allows interaction with the pilot and crew/ground station, and the systems on board the autonomous vehicle. The fundamental issues in autonomous control system modeling and analysis are discussed. It is proposed to utilize a hybrid approach to modeling and analysis of autonomous systems. This will incorporate conventional control methods based on differential equations and techniques for the analysis of systems described with a symbolic formalism. In this way, the theory of conventional control can be fully utilized. It is stressed that autonomy is the design requirement and intelligent control methods appear at present, to offer some of the necessary tools to achieve autonomy. A conventional approach may evolve and replace some or all of the `intelligent' functions. It is shown that in addition to conventional controllers, the autonomous control system incorporates planning, learning, and FDI (fault detection and identification).
Research has been undertaken to achieve an improved understanding of physical phenomena present when a supersonic flow undergoes chemical reaction. A detailed understanding of supersonic reacting flows is necessary to successfully develop advanced propulsion systems now planned for use late in this century and beyond. In order to explore such flows, a study was begun to create appropriate physical models for describing supersonic combustion, and to develop accurate and efficient numerical techniques for solving the governing equations that result from these models. From this work, two computer programs were written to study reacting flows. Both programs were constructed to consider the multicomponent diffusion and convection of important chemical species, the finite rate reaction of these species, and the resulting interaction of the fluid mechanics and the chemistry. The first program employed a finite difference scheme for integrating the governing equations, whereas the second used a hybrid Chebyshev pseudospectral technique for improved accuracy.
The design plan for the personal computer multiple information system interface (PC/MISI) project is discussed. The document is intended to be used as a blueprint for the implementation of the system. Each component is described in the detail necessary to allow programmers to implement the system. A description of the system data flow and system file structures is given.
The radar altimeter being developed for the Ocean Topography Experiment (TOPEX) will have an inherent instrument precision of 2 to 3 cm. While some minor refinements may be possible in the future, major geophysical advances could be made if altimetric measurements over a wide swath of the Earth's surface were possible. The NASA Headquarters Oceanic Processes Branch is supporting a 3-year investigation of the technological issues inherent in the precision measurement of topography from spaceborne platforms at angles off-nadir. To explore the off-nadir measurement of topography, a flexible, airborne radar instrument system is being developed. Its hardware design is now complete, and it is made up of several subsystems. The antenna selected is a dielectric lens of .894 m diameter. The RF subsystem uses phase-locked oscillators, FET solid-state amplifiers, and times four frequency multipliers to develop a transmit signal at a frequency of 36.0 GHz and a local oscillator signal at a frequency of 35.4 GHz. Lecroy 6880 digitizers under computer control digitize the five receiver outputs. The digital subsystem consists of six single-board Heurikon processors. At this time, the instrument construction continues with final system integration planned for November 1988.
An engineering flight demonstration of a 100 kW3 Space Reactor Power System is planned for the mid to late 1990s. An arcjet based propulsion subsystem will be included on the flight demonstraction as a secondary experiment. Two studies, sponsored by the Kay Technologies Directorate of the SDI Organization and managed by the Jet Propulsion Laboratory are currently under way to define that propulsion subsystem. The principal tasks of those contracts and the plans for two later phases, an experimental verification of the concept and a flight qualification/delivery of a flight unit, are described.
The Voyager mission to the giant outer planets of our solar system is described. Scientific highlights include interplanetary cruise, Jupiter, Saturn, Uranus, and their vast satellite and ring systems. Detailed plans are provided for the August 1989 Neptune encounter and subsequent interstellar journey to reach the heliopause. As background, the elements of an unmanned space mission are explained, with emphasis on the capabilities of the spacecraft and the scientific sensors. Other topics include the Voyager Grand Tour trajectory design, deep-space navigation, and gravity-assist concepts. The Neptune flyby is animated through the use of computer-generated, flip-page movie frames that appear in the corners of the publication. Useful historical information is also presented, including facts associated with the Voyager mission. Finally, short summaries are provided to describe the major objectives and schedules for several space missions planned for the remainder of the 20th century.
Software technologies relevant to workstation executives are discussed. Evaluations of problems, potential or otherwise, seen with IBM's Workstation Executive (WEX) 2.5 preliminary design and applicable portions of the 2.5 critical design are presented. Diverse graphics requirements of the Johnson Space Center's Mission Control Center Upgrade (MCCU) are also discussed. The key is to use tools that are portable, compatible with the X window system, and best suited to the requirements of the associated application. This will include a User Interface Language (UIL), an interactive display builder, and a graphic plotting/modeling system. Work sheets are provided for POSIX 1003.4 real-time extensions and the requirements for the Center's automated information systems security plan, referred to as POSIX 1003.6, are discussed.
Creation of an Allotment Plan for the Fixed Satellite Service at the 1988 Space World Administrative Radio Conference (WARC) represented a complex satellite plan synthesis problem, involving a large number of planned and existing systems. Solutions to this problem at WARC-88 required the use of both automated and manual procedures to develop an acceptable set of system positions. Development of an Allotment Plan may also be attempted through solution of an optimization problem, known as the Satellite Location Problem (SLP). Three automated heuristic procedures, developed specifically to solve SLP, are presented. The heuristics are then applied to two specific WARC-88 scenarios. Solutions resulting from the fully automated heuristics are then compared with solutions obtained at WARC-88 through a combination of both automated and manual planning efforts.