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At least 1,783 records · Page 99

Engineering in the 21st century

Reasonable evolutionary trends in federal outlays for aerospace research and development predict a continuing decline in real resources (1970 dollars) until the mid eighties, and a growth thereafter to the 1970 level by 2000, still well below the 1966 peak. Employment levels will parallel this trend with no shortage of available personnel foreseen. These trends characterize a maturing industry. Shifts in outlook toward the economic use of resources, rather than minimum risk at any cost, and toward missions aligned with societal needs and broad national goals will accompany these trends. These shifts in outlook will arise in part in academia, and will, in turn, influence engineering education. By 2000, space technology will have achieved major advances in the management of information, in space transportation, in space structures, and in energy. The economics of space systems must be the primary consideration if the space program foreseen for the 21st century is to become an actuality.

Mccarthy, J. F., Jr.↗

Methods of shield analysis for protection against electrons in space

It is anticipated that many future manned space operations will be radiation limited and that laminated wall structures and the use of new materials will be required to reduce radiation exposure. Methods for electron shield analysis are reviewed in light of anticipated needs in the space program. The most general method is still the Monte Carlo method, which is of limited usefulness for shield analysis due to excessive computer requirements. Methods based on energy deposition coefficients or energy transmission and reflection factors are quite accurate, but are currently limited to aluminum shield material. Analytical methods based on Mar's approximation for the electron transmission factor are relatively general and computer efficient but seriously underestimate shield requirements. A correction to methods using Mar's approximate transmission factor is derived herein and results in a slightly conservative estimate of shield requirements. Techniques for laminated shield design are still lacking.

Wilson, J. W.↗

On humanity's role in space

Manned spaceflight is considered within the framework of two broad categories: human exploitation of space for economic or scientific gain, and human habitation of space as a place where man may live, grow, and actualize himself. With the advent of the Space Shuttle, exploitation of space will take the form of new product development. This will continue during the 1990s as the new products are manufactured on a scale large enough to be profitable. The turn of the century should see major industries in space, and large space habitats. Thus, the question of mankind's existential needs arises. In addition to basic physical needs, the spiritual and cultural requirements of human beings must be considered. The impact of man's presence in space upon human culture in general is discussed with reference to international cooperation, public interest in space programs, scientific advancement, the basic urge to explore, and the density of mankind as a whole; which will become free of external constraints as we step into the cosmos.

Von Puttkamer, J.↗

Anthropometry

Data on body-size measurement are presented to aid in spacecraft design. Tabulated dimensional anthropometric data on 59 variables for 12 selected populations are given. The variables chosen were those judged most relevant to the manned space program. A glossary of anatomical and anthropometric terms is included. Selected body dimensions of males and females from the potential astronaut population projected to the 1980-1990 time frame are given. Illustrations of drawing-board manikins based on those anticipated body sizes are included.

Mcconville, J. T.↗

On-orbit spacecraft reliability

Operational and historic data for 350 spacecraft from 52 U.S. space programs were analyzed for on-orbit reliability. Failure rates estimates are made for on-orbit operation of spacecraft subsystems, components, and piece parts, as well as estimates of failure probability for the same elements during launch. Confidence intervals for both parameters are also given. The results indicate that: (1) the success of spacecraft operation is only slightly affected by most reported incidents of anomalous behavior; (2) the occurrence of the majority of anomalous incidents could have been prevented piror to launch; (3) no detrimental effect of spacecraft dormancy is evident; (4) cycled components in general are not demonstrably less reliable than uncycled components; and (5) application of product assurance elements is conductive to spacecraft success.

Bloomquist, C.↗

Formulation of consumables management models, executive summary

Future manned space programs that have increased launch frequencies and reusable systems require an implementation of new consumables and systems management techniques that relieve both the operations support personnel and flight crew activities. Analytical models and techniques were developed which consist of a Mission Planning Processor (MPP) with appropriate consumables data base, methods of recognizing potential constraint violations in both the planning and flight operations functions, and flight data files for storage/retrieval of information over extended periods interfacing with flight operations processors for monitoring of the actual flights. Consumables subsystems considered in the MPP were electrical power, environmental control and life support, propulsion, hydraulics and auxiliary power.

Torian, J. G.↗

Early space experiments in materials processing

A comprehensive survey of the flight experiments conducted in conjunction with the United States Materials Processing in Space Program is presented. Also included are a brief description of the conditions prevailing in an orbiting spacecraft and the research implications provided by this unique environment. What was done and what was learned are summarized in order to serve as a background for future experiments. It is assumed that the reader has some knowledge of the physical sciences but no background in spaceflight experimentation or in the materials science per se.

Naumann, R. J.↗

Reflections on the NASA standardization effort

The NASA standardization effort which has been in existence for four years is described. A significant number of equipments have been declared standard in order to achieve multimission utilization with the consequent avoidance of high nonrecurring development costs. The small numbers of equipments and significant gaps in time before the next user requires the item raise questions of the value of maintaining a standard, how to assure its producibility economically in the future, and how to prevent its technical obsolescence. Increasing pressures to broaden the participation of industry in the space program have also contributed to a reexamination of the philosophy of standardization.

Sonnemann, H.↗

Technology - The essential base

Establishing the technology base for building a strong viable space program is a complex systems problem which demands continuous attention with full recognition of the dynamic state of the environment in which we operate. In the present paper, an attempt is made to outline, in a condensed form, NASA's approach to selecting those technologies which deserve to be pursued and ensuring that the probability of selecting the right technologies is maximized.

Kramer, J. J.↗

Environmental requirements for flat plate photovoltaic modules for terrestrial applications

The environmental test requirements that have been developed for flat plate modules purchased through Department of Energy funding are described. Concurrent with the selection of the initial qualification tests from space program experience - temperature cycling and humidity - surveys of existing photovoltaic systems in the field revealed that arrays were experiencing the following failure modes: interconnect breakage, delamination, and electrical termination corrosion. These coupled with application-dependent considerations led to the development of additional qualification tests, such as cyclic pressure loading, warped mounting surface, and hail. Rationale for the selection of tests, their levels and durations is described. Comparisons between field-observed degradation and test-induced degradation show a positive correlation with some of the observed field effects. Also, the tests are proving useful for detecting design, process, and workmanship deficiencies. The status of study efforts for the development of environmental requirements for field-related problems is reviewed.

Hoffman, A. R.↗

Shuttle orbital flight test

The initial orbital flight of the shuttle vehicle will involve several operational aspects which differ from previous manned space programs. The asymmetrical shuttle launch configuration undergoes unique aero and thrust loads. The orbiter requires a complex interactive control system during entry. Techniques are described which will be used to minimize the ascent loads. Procedures are outlined which should maximize the entry control margins. The primary objective of the first shuttle flight is to obtain data from which to extract the loads and stability derivatives. Accomplishment of this objective will enable relaxation of constraints on launch winds, entry center of gravity, and crossrange during subsequent flights.

North, W. J.↗

Planetary ionospheres

An analogy is drawn between the Eath's ionosphere and the existence of ionospheres around other planets or natural satellites. An ionosphere is defined as a series of layers (D, E, E1, F2) and their characteristics are discussed. Emphasis is on the role of solar wind impacting with the potential ionosphere and the subsequent chemical and diffusion processes that can be observed. Data from the MARINER and PIONEER space programs are cited concerning measured electron density and ionospheric refractivity of extraterrestrial ionospheres, then an attempt is made to model these atmospheres based on Earth ionosphere theory.

Bauer, S. J.↗

A bibliography of space books and articles from non-aerospace journals, 1957-1977

This bibliography cites over 3,600 articles and books from the nonspecialized secondary literature relating to NASA and to aerospace-related themes. Entries are arranged alphabetically by author in the following categories: (1) space activity; (2) spaceflight: earliest times to the creation of NASA; (3) organization, administration, and management of NASA; (4) aeronautics; (5) boosters and rockets; (6) technology of spaceflight; (7) manned spaceflight; (8) space science; (9) applications; (10) space law; (11) international implications; (12) foreign space programs; (13) domestic public policy and opinion; and (14) economics: impact of NASA, analyses of aerospace industry, and patent policy.

Looney, J. J.↗

Space prospects

A strategy for keeping the Common Market's space effort independent of and competitive with NASA and the space shuttle is discussed. Limited financing is the chief obstacle to this. Proposals include an outer space materials processing project and further development of the Ariane rocket. A manned space program is excluded for the foreseeable future.

Source record↗

Materials processing - A matter of gravity

The paper examines the pervasive influences of gravitational forces on processes used in the preparation of materials employed in earth-based applications and considers the knowledge and benefits which may be derived from the microgravity environment of space in improving upon these constraints. Particular attention is given to the NASA Materials Processing in Space program, which is focused on crystal growth processes, solidification processes, containerless processing, fluid and chemical processes, and bioseparation processes.

Zoller, L. K.↗

Materials science and engineering in space

The influences of gravitational forces on processes used in the preparation of materials employed in earth-based applications are addressed and the benefits which may be derived from the microgravity environment of space in improving on such constraints are considered. Attention is given to the fact that Materials Processing in Space is directed toward the utilization of the unique space environment as a tool to establish a scientific characterization of materials processes for technological exploitation in the public benefit. In the context of enhancement to earth-based technology or implementation of space-based processes for specialized, low volume, high value materials, the thrust of the Materials Processing in Space program is surveyed.

Zoller, L. K.↗