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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS1974

Immiscible materials and alloys

Only immiscible materials which involve a fluid phase have a potential advantage when considered for space processing. Processing of such systems at low gravity can lead to a material which is very homogeneous and contains a finely dispersed mixture of phases. Materials with such structures may exhibit potentially useful properties for such applications as superconductors, dispersion-strengthened materials, superplastic materials, permanent magnets, etc. These conclusions have resulted from review of past efforts in the field of low-g processing of materials containing a liquid phase miscibility gap and from present efforts dealing with such systems. These studies have concentrated on precipitation of liquid droplets in a host liquid during cooling through the miscibility gap. This effort has been to study the agglomeration of the droplets both experimentally and through computer simulation in order to understand the mechansism involved and to deduce the effect of gravity on the droplet distribution and resulting structure of the solidified material. The agglomeration mechanisms treated in detail are those due to diffusional growth and collision processes caused by Stokes on convection current-induced droplet migration.

Markworth, A. J.↗
NASA NTRS1974

External field effects on solidification - Macroscopic and microscopic models

Comparison of theoretical effects of magnetic and gravitational fields on melts of metals and semiconductors provides two kinds of insight into space processing materials problems. First, the task of comparing effects of the two fields yields mathematical models which may be used to estimate material properties and responses to processing under various field conditions. Then, by using these models, microgravity effects can be inferred from magnetic field data already obtained in laboratories on earth. Magnetohydrodynamics (static and oscillating fields) and the Free Volume Model are used to study macroscopic effects, and Sekerka's interface stability theory is used to show how external fields can affect microsegregation. It is demonstrated that the mathematical formalism is essentially the same for describing macroscopic effects of both microgravity and magnetic fields.

Miller, R. I.↗
NASA NTRS1974

Skylab experiments on semiconductors and alkali halides

The space processing experiments performed during the Skylab missions included one on single crystal growth of germanium selenide and telluride, one on pure and doped germanium crystals, two on pure and doped indium antimonide, one on gallium-indium-antimony systems, and one on a sodium chloride-sodium fluoride eutectic. In each experiment, three ampoules of sample were processed in the multipurpose electric furnace within the Skylab Materials Processing Facility. All were successful in varying degrees and gave important information about crystal growth removed from the effects of earth surface gravity.

Lundquist, C. A.↗
NASA NTRS1975

Apollo-Soyuz test project

Experiments proposed for the Apollo-Soyuz space mission are discussed. Data focus of space processing and manufacturing, earth surveys, and life sciences. Special efforts were made to test the compatibility of the rendezvous and docking systems for manned spacecraft. Mission planning programs, personnel training, and spacecraft modifications for both spacecraft are included.

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NASA NTRS1975

Investigation of immiscible systems and potential applications

The droplet coalescence kinetics at 0 g and 1 g were considered for two systems which contained liquid droplets in a host liquid. One of these (Al-In) typified a system containing a liquid phase miscibility gap and the order (oil-water) a mixture of two essentially insoluble liquids. A number of coalescence mechanisms potentially prominent at low g in this system were analyzed and explanations are presented for the observed unusual stability of the emulsion. Ground base experiments were conducted on the coalescence of In droplets in and Al-In alloy during cooling through the miscibility gap at different cooling rates. These were in qualitative agreement with the computer simulation. Potential applications for systems with liquid phase miscibility gaps were explored. Possibilities included superconductors, electrical contact materials, superplastic materials, catalysts, magnetic materials, and others. The role of space processing in their production was also analyzed.

Markworth, A. J.↗
NASA NTRS1975

High purity tungsten targets

High purity tungsten, which is used for targets in X-ray tubes was considered for space processing. The demand for X-ray tubes was calculated using the growth rates for dental and medical X-ray machines. It is concluded that the cost benefits are uncertain.

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NASA NTRS1974

Space station 'Skylab' - The harvest begins

Initial difficulties connected with the damage suffered by the space station during the launching operation and approaches for overcoming these difficulties are discussed along with the results obtained by the astronauts in their investigations. Attention is given to biomedical results, new solar discoveries, observations of the earth, materials research, and the new products obtained as a result of space processing.

Von Puttkamer, J.↗
NASA NTRS1975

The Concept Verification Testing of a materials science payload

The Concept Verification Testing (CVT) project at the Marshall Space Flight Center, Alabama is a developmental activity that supports Shuttle Payload projects such as Spacelab. It provides an operational one-g environment for testing NASA and other agency experiment and support systems concepts that may be used in Shuttle. A dedicated Materials Science Payload was tested in the General Purpose Laboratory (GPL) in December 1974 in order to assess the requirements of a Space Processing payload on a Spacelab type facility. Physical and functional integration of the experiments into the facility was studied, and the impact of the experiments on the facility (and vice versa) was evaluated. The Principal Investigators (PI) who had proposed experiments were onboard and in a consulting status on the ground. The significant results of the week-long simulation will be discussed.

Griner, C. S.↗
NASA NTRS1975

Studies of rotating liquid floating zones on Skylab IV

Liquid zones of water, soap solution and soap foam were deployed between two aligned circular disks which were free to rotate about the zone axis in the microgravity environment of Skylab IV. Such a configuration is of interest in the containerless handling of melts for possible future space processing crystal growth experiments. Three basic types of zone surface deformation and instability were observed for these rotational conditions; axisymmetric shape changes under single disk rotation, nonaxisymmetric, whirling, C-modes for long zones with equal rotation of both disks, and capillary wave phenomena for short zones with equal rotation of both disks. The sources of these instabilities and the conditions promoting them are analyzed in detail from video tape recordings of the Skylab experiments.

Carruthers, J. R.↗
NASA NTRS1975

The design, development, fabrication and testing of two (2) Non-Spin Platforms, (NSP)

The non spin platform is a means for achieving the very low acceleration requirements for cost effective space processing experiments on research rocket flights. These platforms have a low initial cost, are re-usable and have extremely low refurbishment cost. In order to attain this goal, commercially available components were used and only the necessary quality control standards were imposed. A detailed system description, the very few design problems encountered, the operational procedures (both pre-flight and post-flight), and the maintenance requirements are described.

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NASA NTRS1976

The concept verification testing of materials science payloads

The concept Verification Testing (CVT) project at the Marshall Space Flight Center, Alabama, is a developmental activity that supports Shuttle Payload Projects such as Spacelab. It provides an operational 1-g environment for testing NASA and other agency experiment and support systems concepts that may be used in shuttle. A dedicated Materials Science Payload was tested in the General Purpose Laboratory to assess the requirements of a space processing payload on a Spacelab type facility. Physical and functional integration of the experiments into the facility was studied, and the impact of the experiments on the facility (and vice versa) was evaluated. A follow-up test designated CVT Test IVA was also held. The purpose of this test was to repeat Test IV experiments with a crew composed of selected and trained scientists. These personnel were not required to have prior knowledge of the materials science disciplines, but were required to have a basic knowledge of science and the scientific method.

Griner, C. S.↗
NASA NTRS1976

Solution to the differential equation for combined radiative and convective cooling for a heated sphere

A solution is presented for the differential equation relating the combined effects of radiative and forced convective cooling for a heated sphere. The equation has the form where T and t are the variables temperature and time, respectively, and K sub o, T sub o, and H are constants. The solution can be used as a guideline for the design and understanding of space processing phenomena.

Wills, F. D.↗
NASA NTRS1976

Undercooling of materials during solidification in space

A theoretical research program was undertaken on the under cooling and solidification of materials under variable external field conditions. A catalog of theories and models of nucleation of solid phases in the melt is provided, as is a discussion of the relation of undercooling to intermolecular potentials, the dependence of growth rate on undercooling, the influence of undercooling on liquid-solid interface stability and solid structure, the direct effects of external fields on melts, the relation of solid physical properties to structure and the role of nucleants in solidification. Results of the theoretical analysis of several experiments related to the space processing applications program are given, and recommendations for future experiments and further theoretical developments along with procedures for correlation of theory and experiment are specified.

Miller, R. I.↗
NASA NTRS1976

Rate-control system /RCS/ for zero-gravity experiments

A sounding rocket payload, free falling in space, with low angular body rates provides a near zero gravity environment. To efficiently utilize the time above the earth's atmosphere, a positive means of controlling angular body rates must be provided for the payload. A rate-control system (RCS) was designed at the Goddard Space Flight Center (GSFC) to meet the requirements of the Space Processing Applications Rocket Program and for use on the Black Brant-V sounding rocket. After the sounding rocket exits the atmosphere, the payload separates, the RCS reduces the initial angular rates to low levels and maintains the low levels until the payload reenters the atmosphere. The maiden flight of the RCS was aboard a NASA sounding rocket. The system performed as expected, and the payload experienced a low-G environment below 0.0001 G for 300 sec. This paper describes the design criteria, the components used, and the mode of operation.

Schuler, B. C.↗
NASA NTRS1976

Low-gravity homogenization and solidification of aluminum antimonide

The III-V semiconducting compound AlSb shows promise as a highly efficient solar cell material, but it has not been commercially exploited because of difficulties in compound synthesis. Liquid state homogenization and solidification of AlSb were carried out in the Apollo-Soyuz Test Project Experiment MA-044 in the hope that compositional homogeneity would be improved by negating the large density difference between the two constituents. Post-flight analysis and comparative characterization of the space-processed and ground-processed samples indicate that there are major homogeneity improvements in the low-gravity solidified material.

Ang, C.-Y.↗
NASA NTRS1976

Crystal growth from the vapour phase (ASTP experiment MA-085)

The positive effects of microgravity on crystal quality and fundamental properties of the vapor transport reaction were established by analyzing the results of three transport experiments on multi-component systems performed during the Apollo Soyuz Test Project (ASTP) mission. The systems employed were GeSe(0.99)Te(0.01) - GeI4 (A), GeS(0.98)Se(0.02) - GeCl4 (B), and GeS - GeCl4-Ar (C). The crystallographic analysis is based on a direct comparison of space and ground-based (prototype) crystals, employing X-ray diffraction, microprobe, microscopic, and chemical etching techniques. The results demonstrate a considerable improvement of the space-grown crystals in terms of chemical and crystalline homogeneity, surface morphology, and bulk perfection relative to ground specimens. The confirmation of greater mass transport rates than predicted for micro-gravity by present vapor transport models is of basic scientific and practical importance for the improvement of transport models and techniques on earth and for the development of a transport model for space conditions. The internal consistency and agreement between ASTP and Skylab results obtained for different compounds, transport agents, and temperature gradients strongly support the validity of these observations. The combined findings of improved crystal quality and high mass transport rates are of technological significance for space-processing applications.

Wiedemeier, H.↗
NASA NTRS1977

Space station systems analysis study. Part 2, Volume 2

Specific system options are defined and identified for a cost effective space station capable of orderly growth with regard to both function and orbit location. Selected program options are analyzed and configuration concepts are developed to meet objectives for the satellite power system, earth servicing, space processing, and supporting activities. Transportation systems are analyzed for both LEO and GEO orbits.

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