STS users study (study 2.2). Volume 1: Executive summary

The space transportation system (STS) and ancillary equipment user studies are presented. Space shuttle data and planning requirements needed by the STS user are discussed along with the potential for common usage of multi-mission support equipment by the military and other aerospace personnel

Comparing the effectiveness of testing methods in improving programs: the effect of variations in program quality

We compare the efficacy of different testing methods for improving the reliability of software. Specifically, we use modelling to compare “operational” testing, in which test cases are chosen according to their probability of occurring in actual use of the software, against “debug” testing methods, in which the testers look for test cases which they consider likely to cause failure, or that satisfy some coverage criterion. We base our comparisons on the reliability reached by the program at the end of testing. Differently from previous studies, we consider the probability distribution of the achieved reliability, and thus the probability of satisfying specific requirements, rather than just the average reliability achieved. We take account of two sources of variation. The variation between the actual test histories that are possible for a given program and a given test method: and the fact that different programs start testing with different faults and initial reliability levels. By necessity, we use very simplified models of reality. Yet, we can show some interesting conclusions with important practical consequences. In general, there are stronger arguments in favor of operational testing than previous studies have show

Mars Geoscience Orbiter and Lunar Geoscience Orbiter

The feasibility of using the AE/DE Earth orbiting spacecraft design for the LGO and/or MGO missions was determined. Configurations were developed and subsystems analysis was carried out to optimize the suitability of the spacecraft to the missions. The primary conclusion is that the basic AE/DE spacecraft can readily be applied to the LGO mission with relatively minor, low risk modifications. The MGO mission poses a somewhat more complex problem, primarily due to the overall maneuvering hydrazine budget and power requirements of the sensors and their desired duty cycle. These considerations dictate a modification (scaling up) of the structure to support mission requirements

Space shuttle electrical power generation and reactant supply system

The design philosophy and development experience of fuel cell power generation and cryogenic reactant supply systems are reviewed, beginning with the state of technology at the conclusion of the Apollo Program. Technology advancements span a period of 10 years from initial definition phase to the most recent space transportation system (STS) flights. The development program encompassed prototype, verification, and qualification hardware, as well as post-STS-1 design improvements. Focus is on the problems encountered, the scientific and engineering approaches employed to meet the technological challenges, and the results obtained. Major technology barriers are discussed, and the evolving technology development paths are traced from their conceptual beginnings to the fully man-rated systems which are now an integral part of the shuttle vehicle

Software Engineering Laboratory (SEL) Data Base Maintenance System (DBAM) user's guide and system description

The Software Engineering Laboratory (SEL) Data Base Maintenance System (DBAM) is explained. The various software facilities of the SEL, DBAM operating procedures, and DBAM system information are described. The relationships among DBAM components (baseline diagrams), component descriptions, overlay descriptions, indirect command file listings, file definitions, and sample data collection forms are provided

TOPEX satellite option study

The basic design of the fleet satellite communication spacecraft (FLTSATCOM) can easily accommodate any of the three payload options for the ocean dynamic topography experiment (TOPEX). The principal mission requirements as well as the payload accommodations and communications systems needed for launching this payload are reviewed. The existing FLTSATCOM satellite design is identified and the approaches for the proposed propulsion system are described in addition to subsystems for mechanical; power; attitude and velocity control; and telemetry, tracking and control are described. The compatability of FLTSATCOM with the launch vehicle is examined and its capabilities vs TOPEX requirements are summarized. Undetermined changes needed to meet data storage, thermal control, and area to mass ratio requirements are discussed. Cost estimates are included for budgetary and planning purposes. The availability of the described design is assessed based on the continuing production of FLTSATCOM spacecraft during the schedule span planned for TOPEX

Performance interface document for the S-band diplexer for space users of NASA networks

This report discusses the test results and interfacing information of the S-band diplexer development program supported by RTOP 310 funding. The program was implemented to reduce the S-band transponder noise figure by minimizing the receive channel insertion loss and to also provide Space Transportation System (STS) compatibility by providing 70-db rejection up to 16 GHz in the receive channel. This compatibility includes rejection of signals from the Shuttle S-band Data Link, the K-band Data Link, and the K-band Rendezvous Radar. The first of many projects to benefit from this accomplishment was the Earth Radiation Budget Satellite (ERBS)

Space biology initiative program definition review. Trade study 2: Prototype utilization in the development of space biology hardware

The objective was to define the factors which space flight hardware developers and planners should consider when determining: (1) the number of hardware units required to support program; (2) design level of the units; and (3) most efficient means of utilization of the units. The analysis considered technology risk, maintainability, reliability, and safety design requirements for achieving the delivery of highest quality flight hardware. Relative cost impacts of the utilization of prototyping were identified. The development of Space Biology Initiative research hardware will involve intertwined hardware/software activities. Experience has shown that software development can be an expensive portion of a system design program. While software prototyping could imply the development of a significantly different end item, an operational system prototype must be considered to be a combination of software and hardware. Hundreds of factors were identified that could be considered in determining the quantity and types of prototypes that should be constructed. In developing the decision models, these factors were combined and reduced by approximately ten-to-one in order to develop a manageable structure based on the major determining factors. The Baseline SBI hardware list of Appendix D was examined and reviewed in detail; however, from the facts available it was impossible to identify the exact types and quantities of prototypes required for each of these items. Although the factors that must be considered could be enumerated for each of these pieces of equipment, the exact status and state of development of the equipment is variable and uncertain at this time

The aerodynamic challenges of the design and development of the space shuttle orbiter

The major aerodynamic design challenge at the beginning of the United States Space Transportation System (STS) research and development phase was to design a vehicle that would fly as a spacecraft during early entry and as an aircraft during the final phase of entry. The design was further complicated because the envisioned vehicle was statically unstable during a portion of the aircraft mode of operation. The second challenge was the development of preflight aerodynamic predictions with an accuracy consistent with conducting a manned flight on the initial orbital flight. A brief history of the early contractual studies is presented highlighting the technical results and management decisions influencing the aerodynamic challenges. The configuration evolution and the development of preflight aerodynamic predictions will be reviewed. The results from the first four test flights shows excellent agreement with the preflight aerodynamic predictions over the majority of the flight regimes. The only regimes showing significant disagreement is confined primarily to early entry, where prediction of the basic vehicle trim and the influence of the reaction control system jets on the flow field were found to be deficient. Postflight results are analyzed to explain these prediction deficiencies

Integrated payload and mission planning, phase 3. Volume 2: Logic/Methodology for preliminary grouping of spacelab and mixed cargo payloads

The logic and methodology for a preliminary grouping of Spacelab and mixed-cargo payloads is proposed in a form that can be readily coded into a computer program by NASA. The logic developed for this preliminary cargo grouping analysis is summarized. Principal input data include the NASA Payload Model, payload descriptive data, Orbiter and Spacelab capabilities, and NASA guidelines and constraints. The first step in the process is a launch interval selection in which the time interval for payload grouping is identified. Logic flow steps are then taken to group payloads and define flight configurations based on criteria that includes dedication, volume, area, orbital parameters, pointing, g-level, mass, center of gravity, energy, power, and crew time