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Opportunities for research at Marshall Space Flight Center's Materials and Processes Laboratory, Space Sciences Laboratory, and Systems Dynamics Laboratory are described. Information is provided for applicants desiring designation as a research associate and a list of laboratory directors and research advisors is provided.
The Communications Link Analysis and Simulation System (CLASS) is a comprehensive, computerized communications and tracking system analysis tool under development by the Networks Directorate of the NASA/GSFC. The primary use of this system is to provide the capability to predict the performance of the Tracking and Data Relay Satellite system (TDRSS) User Communications and Tracking links through the TDRSS. The general capabilities and operational philosophy of the current and final versions of the CLASS are described along with some examples of analyses which have been performed utilizing the capabilities of this system.
An executable assertion is a logical statement about the variables or a block of code. If there is no error during execution, the assertion statement results in a true value. Executable assertions can be used for dynamic testing of software. They can be employed for validation during the design phase, and exception and error detection during the operation phase. The present investigation is concerned with the problem of writing executable assertions, taking into account the use of assertions for testing flight software. They can be employed for validation during the design phase, and for exception handling and error detection during the operation phase The digital flight control system and the flight control software are discussed. The considered system provides autopilot and flight director modes of operation for automatic and manual control of the aircraft during all phases of flight. Attention is given to techniques for writing and using assertions to test flight software, an experimental setup to test flight software, and language features to support efficient use of assertions.
As the NASA Center responsible for assembly, checkout, servicing, launch, recovery, and operational support of Space Transportation System elements and payloads, Kennedy Space Center is placing increasing emphasis on the Center's research and technology program. In addition to strengthening those areas of engineering and operations technology that contribute to safe, more efficient, and more economical execution of our current mission, we are developing the technological tools needed to execute the Center's mission relative to Space Station and other future programs. The Engineering Development Directorate encompasses most of the laboratories and other Center resources that are key elements of research and technology program implementation and is responsible for implementation of the majority of the projects in this Kennedy Space Center 1985 Annual Report. The report contains brief descriptions of research and technology projects in major areas of Kennedy Space Center's disciplinary expertise.
The NASA Lewis Research Center's research and technology accomplishments for fiscal year 1985 are summarized. The report is organized into five major sections covering aeronautics, aerospace technology, spaceflight systems, space station systems, and computational technology support. This organization of the report roughly parallels the organization of the Center into directorates. Where appropriate, subheadings are used to identify special topics under the major headings. Results of all research and technology work performed during the fiscal year are contained in Lewis-published technical reports and presentations prepared either by Lewis scientists and engineers or by contractor personnel. In addition, significant results are presented by university faculty or graduate students in technical sessions and in journals of the technical societies. For the reader who desires more information about a particular subject, the Lewis contact will provide that information or references. In 1985, five Lewis products were selected by Research and Development Magazine for IR-100 awards. All are described and identified. In addition, the Lewis Distinguished Paper for 1984 to 1985, which was selected by the Chief Scientist and a research advisory board, is included and so identified.
Excerpts from a chapter of a monograph, Oceanology in the Year 2000, which has been prepared for publication at the USSR Academy of Sciences' Institute of Oceanology, is presented. The author of this chapter is A. S. Morin, corresponding member of the USSR Academy of Sciences and director of the oceanology institute. The monograph is said to be the collective work of a group of specialists. Monin views prospective developments of oceanology and oceanology related research and development, technology and expedition research.
This volume contains all the hearings of the Presidential Commission on the Space Shuttle Challenger accident from 26 February to 2 May 1986. Among others is the testimony of L. Mulloy, Manager, Space Shuttle Solid Rocket Booster Program, Marshall Space Flight Center and G. Hardy, Deputy Director, Science and Engineering, Marshall Space Flight Center.
A piloted simulation of three head-down display (HDD) concepts with flight-director guidance superimposed on forward-looking infrared (FLIR) imagery was performed to evaluate the task of low-level, terrain-following (TF), manual helicopter flight. The three display concepts were examined for the purpose of finding ways by which aircraft flight-attitude and command symbols and FLIR imagery could be integrated onto one instrument. In all cases, the FLIR imagery was centered on the flight-path vector of the aircraft. The three displays were then characterized by having: (1) pitch attitude conformal to the FLIR imagery; (2) pitch attitude conformal to the FLIR imagery, but with an increase in the scaling; and (3) pitch attitude nonconformal to the FLIR imagery with the same pitch scaling as in (2). The simulation was conducted on the Vertical Motion Simulator (VMS) at Ames Research Center, using NASA and Air Force test pilots. The pilots indicated that the nonconformal pitch attitude and FLIR display was the preferred way to display information because of the absence of pitch-attitude information on displays (1) and (2) during some portions of the operational flight envelope.
This paper discusses the terminal area guidance and terrain following system developed for the USAF HH-60A Night Hawk Search and Rescue Helicopter. A Multi-Mode Radar and three-cue Flight Path Vector Director provide a terrain following capability at all airspeeds, allowing a decelerating approach to a hover over varying terrain to a designated point. Properties of the terrain following design are discussed. Simulation results using the NASA Ames piloted Vertical Motion Simulator are presented.
Trials were run on a six degree of freedom combat helicopter simulator to evaluate head-down displays with integrated FLIR imagery for terrain-following, course-steering, and transition to approach and hover helicopter pilot tasks. Three display formats were tested, providing varying levels of symbology for, e.g., the flight path angle, pitch-attitude data, vertical speed, altitude, etc. The pilots were also furnished flight director guidance, i.e., terrain-following, course steering, airspeed hold, and approach to hover. All the displays permitted the pilots to fly satisfactory mission in the CGI scenarios. The results revealed that the pilots preferred a nonconformal FLIR display superposition.
The Space Station Program (SSP) will consist, in part, of a permanently orbiting facility composed of a mix of manned and unmanned elements. To insure that such a facility will be an operationally viable and productive one, capable of performing a myriad of assigned missions, special attention must be given to the following operational disciplines during the design and development of the SSP systems and subsystems: (1) Automation/Autonomy, (2) Customer Interfaces/Operations, (3) Habitability/Crew Productivity, (4) Maintainability, and (5) Logistics. In order to properly address these disciplines, from an operations point of view, the Director of the Space Station Task Force (SSTF) formed the Operations Working Group (OWG) in July 1982, and chartered this group to develop the top level operational technical and management-approach philosophies and requirements for the SSP. This paper attempts to summarize the results and conclusions reached by the OWG after an 18 month intensive study effort.
The NASA Lyndon B. Johnson Space Center Mission Operations Directorate (MOD) has the responsibility for planning, training, and implementing of flight operations in support of the National Space Transportation System (STS) Program. In this role, MOD has responsibility for the operational interface with customers and the translation of customer requirements into operating plans to satisfy their objectives. The basic objectives of flight operations are to maximize mission success, to minimize risks to the Orbiter and the crew, to decrease operating costs, and to achieve an effective balance in the application of all operational resources. In the National STS Program, to date, 20 missions have been flown and the process for planning, training, and flight operations has been thoroughly exercised. In this paper, MOD's performance is assessed, and those areas in which our initial operating concepts have been successful as well as those in which significant additional work is required are identified.
An experimental and analytical study was undertaken to investigate human interaction with a simple multiloop manual control system in which the human's activity was systematically varied by changing the level of automation. The system simulated was the longitudinal dynamics of a hovering helicopter. The automation-systems-stabilized vehicle responses from attitude to velocity to position and also provided for display automation in the form of a flight director. The control-loop structure resulting from the task definition can be considered a simple stereotype of a hierarchical control system. The experimental study was complemented by an analytical modeling effort which utilized simple crossover models of the human operator. It was shown that such models can be extended to the description of multiloop tasks involving preview and precognitive human operator behavior. The existence of time optimal manual control behavior was established for these tasks and the role which internal models may play in establishing human-machine performance was discussed.
Simplified structures for longitudinal control laws that reduce an aircraft's response to the strong head-tailwind and downdraft variations associated with microbursts are presented. They are based on non-zero-set-point linear-quadratic regulators that command throttle setting and angle of attack as functions of velocity and flight path angle, and they can incorporate direct measurements of the wind profile if available. Selection of cost functions to be minimized by feedback control has been aided by a prior study of classical control laws and exact nonlinear-optimal flight paths through realistic microburst wind profiles. The resulting optimal control laws have an adaptive, dual-mode structure that can be implemented either in flight-director logic or in an autopilot.
The design of the model rotor and the comparative study of coupled beam theory and the finite element analysis performed earlier at the Aerostructures Directorate by Robert Hodges and Mark Nixon is examined. Attention is focused upon two matters: (1) an examination of the small discrepancies between twist angle predictions under pure torque and radial loading, and (2) an assessment of nonclassical effects in bending behavior. The primary objective is understanding, particularly with regard to cause and effect relationships. Understanding, together with the simple, affordable nature of the coupled beam analysis, provides a sound basis for design.
The Lewis Strategic Plan was updated for 1985 and beyond. Major programs for the space station, the advanced turboprop, the Advanced Communications Technology Satellite (ACTS), and the Altitude Wind Tunnel were begun or greatly expanded during 1984. In parallel, The Lewis aeropropulsion research and technology program was extensively evaluated and reviewed; a reduced and reoriented program emerged. The thrusts and implementation plans for these programs are described as they pertain to the individual directorates. Other key accomplishments and plans are summarized.
This report describes the low-temperature transistor modules designed for use with the MSFC mid-infrared array. The modules were developed in the Space Science Laboratory at Marshall Space Flight Center with Center Director's Discretionary Funds. The transistors (JFETs), which operate at a temperature of 77 K, are epoxied to a copper surface attached to a Teflon substrate. The module substrate insulates the JFETs from the 1.5K detector work surfaces and provides a convenient mounting structure for additional components such as solder pins. These modules have maintained their structural integrity during repeated temperature cycling, and they have to be convenient during maintenance and servicing of the infrared array.
Existing international space law as well as the best interest of all nations are consistent with the establishment of a user-based international organization, herein called INTERMARS. INTERMARS would provide access to facilities and services at a Martian base which would be of high functional potential, quality, safety, and reliability. These opportunities would be available on an open and nondiscriminatory basis to all peaceful users and investors. INTERMARS is a model organization concept tailored to provide cooperative international management of a Martian base for the benefit of its members, users, and investors. Most importantly, INTERMARS would provide such management through a sharing of both sovereignty and opportunity rather then unilateral control by any one nation or set of competing nations. Through an Assembly of Parties, a Board of Governors, a Board of Users and Investors, and a Director General, INTERMARS would meet its primary goal as it would be in the self-interest of all members, users, and investors to do so. The internal structure and philosophy of INTERMARS would provide not only for all participants to have representation in decisions affecting its activities, but also would insure effective and responsive management. Surely this is the precedent wished for, to establish for mankind at the now not-so-distant shores of the new ocean of space.