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NASA NTRS2004

Te-and Zn-Doped InSb Crystals Grown in Microgravity

In 2002, within the SUBSA (Solidification Using a Baffle in Sealed Ampoules) investigation, seven doped InSb crystals were grown in microgravity at the International Space Station. The key goals of the SUBSA investigation are: (a) to clarify the origin of the melt convection in space laboratories; (b) to reduce melt convection to the level which allows reproducible diffusion-controlled segregation; (e) to explore the submerged baffle process and liquid encapsulation in microgravity. 30 crystal growth experiments were conducted in the ground unit, to optimize the design of flight ampoules and to test the transparent SUBSA furnace developed by TecMasters Inc. The specially designed furnace, allowed observation of the crystal growth process (melting, seeding, motion of the solid-liquid interface, etc.). In the summer of 2002, eight crystal growth experiments were conducted in the Microgravity Science Glovebox (MSG) facility at the ISS. Four Te-doped (k = 0.5) and three Zn-doped (k2.9) crystals were grown on undoped seeds. In one experiment, we were not able to seed and grow. The seven grown crystals were sectioned and analyzed using SIMS. The design of the SUBSA ampoules, the segregation data and the video images obtained during the SUBSA flight experiments will be presented and discussed.

Ostrogorsky, A. G.↗

NASA NTRS1991

Neurosciences research in space - Future directions

In order to gain a better understanding of the effects of long-duration space missions on the central nervous system, near-term research, to take place from 1990-1995, will be directed at investigating the acute effects of microgravity and the 'space adaptation syndrome'. These include experiments scheduled for the Spacelab Life Sciences 1 which is designed to evaluate changes in the visual, vestibular, and proprioceptive systems. An extensive series of experiments, collectively termed Microgravity Vestibular Investigations (MVI), is also planned for the IML-1 mission to be flown in 1992. The IML-2 mission will emphasize behavior and performance, biological rhythms, and further vestibular studies. Mid-term goals, projected to be achieved from 1995-2000, include the use of new technology such as magnetic recording techniques. Long-term goals are also discussed including studies dealing with neuronal plasticity and sensory substitution, augmentation, and robotic telepresence.

Sulzman, Frank M.↗

NASA NTRS2001

Evidence of root zone hypoxia in Brassica rapa L. grown in microgravity

A series of experiments was conducted aboard the U.S. space shuttle and the Mir space station to evaluate microgravity-induced root zone hypoxia in rapid-cycling Brassica (Brassica rapa L.), using both root and foliar indicators of low-oxygen stress to the root zone. Root systems from two groups of plants 15 and 30 d after planting, grown in a phenolic foam nutrient delivery system on the shuttle (STS-87), were harvested and fixed for microscopy or frozen for enzyme assays immediately postflight or following a ground-based control. Activities of fermentative enzymes were measured as indicators of root zone hypoxia and metabolism. Following 16 d of microgravity, ADH (alcohol dehydrogenase) activity was increased in the spaceflight roots 47% and 475% in the 15-d-old and 30-d-old plants, respectively, relative to the ground control. Cytochemical localization showed ADH activity in only the root tips of the space-grown plants. Shoots from plants that were grown from seed in flight in a particulate medium on the Mir station were harvested at 13 d after planting and quick-frozen and stored in flight in a gaseous nitrogen freezer or chemically fixed in flight for subsequent microscopy. When compared to material from a high-fidelity ground control, concentrations of shoot sucrose and total soluble carbohydrate were significantly greater in the spaceflight treatment according to enzymatic carbohydrate analysis. Stereological analysis of micrographs of sections from leaf and cotyledon tissue fixed in flight and compared with ground controls indicated no changes in the volume of protoplast, cell wall, and intercellular space in parenchyma cells. Within the protoplasm, the volume occupied by starch was threefold higher in the spaceflight than in the ground control, with a concomitant decrease in vacuolar volume in the spaceflight treatment. Both induction of fermentative enzyme activity in roots and accumulation of carbohydrates in foliage have been repeatedly shown to occur in response to root zone oxygen deprivation. These results indicate that root zone hypoxia is a persistent challenge in spaceflight plant growth experiments and may be caused by microgravity-induced changes in fluid and gas distribution.

long duration↗

NASA NTRS1998

Experiment 3: Zeolite Crystal Growth in Microgravity- The USML-2 Mission

The extensive use of zeolites and their impact on the world's economy leads to many efforts to characterize their structure, and to improve the knowledge base for nucleation and growth of these crystals. The Zeolite Crystal Growth (ZCG) experiment on USML-2 aims to enhance the understanding of nucleation and growth of zeolite crystals while attempting to provide a means of controlling the defect concentration in microgravity. Zeolites A, X, Beta, and Silicalite were grown during the 16-day USML-2 mission. The solutions where the nucleation event was controlled yielded larger and more uniform crystals of better morphology and purity than their terrestrial/control counterparts. Space-grown Beta crystals were free of line defects while terrestrial/controls had substantial defects.

Bac, Nurcan↗

NASA NTRS1993

Opposed-Flow Flame Spreading in Reduced Gravity

Experimental results obtained in drop towers and in Space Shuttle based experiments coupled with modelling efforts are beginning to provide information that is allowing an understanding to be developed of the physics of opposed-flow flame spread at reduced gravity where the spread rate and flow velocity are comparable and of the role played by radiative and diffusive processes in flame spreading in microgravity. Here we describe one Space Shuttle based experiment on flame spreading in a quiescent environment, the Solid Surface Combustion Experiment, SSCE, one planned microgravity experiment on flame spreading in a radiatively-controlled, forced opposing flow environment, the Diffusive and Radiative Transport in Fires Experiment, DARTFire, modelling efforts to support these experiments, and some results obtained to date.

Altenkirch, Robert A.↗

NASA NTRS1997

SAMS Acceleration Measurements on Mir from November 1995 to March 1996

The NASA Microgravity Science and Applications Division (MSAD) sponsors science experiments on a variety of microgravity carriers, including Orbiter missions and Russia's Mir space station. The MSAD sponsors the Space Acceleration Measurement System (SAMS) at the NASA Lewis Research Center (LERC) to support these science experiments by providing acceleration measurements to characterize the microgravity environment to which the experiments were exposed. The LeRC Principal Investigator Microgravity Services (PIMS) project supports principal investigations of microgravity science experiments as they evaluate the effects of varying acceleration levels on their experiments. In 1994, a SAMS unit was installed on the Mir space station. In a manner similar to Orbiter mission support, the SAMS unit supports science experiments from the U.S. and Russia by measuring the microgravity environment during experiment operations. Previous reports have summarized the SAMS data acquired during the period from September 1994 to November 1995. During the time period from November 1995 to March 1996, the primary SAMS-supported experiment was a Protein Crystal Growth (PCG) experiment. SAMS data were obtained during the PCG operations on Mir in accordance with the requirements specified by the PCG Principal Investigator. Also included in this data are mission events of interest, such as the undocking of STS-74 from Mir (November 1995) and the docking of Atlantis (STS-76) to Mir in March 1996. This report presents an overview of the SAMS data recorded in the interval from November 1995 to March 1996.

DeLombard, Richard↗

NASA NTRS2015

The Zero Boil-Off Tank Experiment Contributions to the Development of Cryogenic Fluid Management

The Zero Boil-Off Technology (ZBOT) Experiment involves performing a small scale ISS experiment to study tank pressurization and pressure control in microgravity. The ZBOT experiment consists of a vacuum jacketed test tank filled with an inert fluorocarbon simulant liquid. Heaters and thermo-electric coolers are used in conjunction with an axial jet mixer flow loop to study a range of thermal conditions within the tank. The objective is to provide a high quality database of low gravity fluid motions and thermal transients which will be used to validate Computational Fluid Dynamic (CFD) modeling. This CFD can then be used in turn to predict behavior in larger systems with cryogens. This paper will discuss the current status of the ZBOT experiment as it approaches its flight to installation on the International Space Station, how its findings can be scaled to larger and more ambitious cryogenic fluid management experiments, as well as ideas for follow-on investigations using ZBOT like hardware to study other aspects of cryogenic fluid management.

Fluid management↗

NASA NTRS1991

Crystal Growth Furnace - An overview of the system configuration and planned experiments on the first United States Microgravity Laboratory mission

Attention is given to the Crystal Growth Furnace (CGF) currently in the Level IV integration cycle at the Kennedy Space Center in preparation for its maiden flight on the first United States Microgravity Laboratory (USML-1) mission to be launched in May 1992. CGF was developed for NASA under the Microgravity Science and Application division programs at NASA Headquarters. An overview of the CGF system and the system configuration for the USML-1 mission are presented, and the planned on-orbit experiments are described. The four important scientific experiments selected from industry and educational institutions for the CGF USML-1 mission will enable a better understanding of the complex phenomena inherent in materials processing that will lead to the ultimate improvement of both processes and materials. Crystal growth by chemical vapor transport has resulted in improved growth conditions with crystal morphology, lower defect densities, and higher growth rates than terrestrially observed.

Srinivas, R.↗

NASA NTRS1995

Crystal Growth Furnace System Configuration and Planned Experiments on the Second United States Microgravity Laboratory Mission

The Crystal Growth Furnace (CGF) is currently undergoing modifications and refurbishment and is currently undergoing modifications and refurbishment and is manifested to refly on the Second United States Microgravity Laboratory (USML-2) mission scheduled for launch in September 1995. The CGF was developed for the National Aeronautics and Space Administration (NASA) under the Microgravity Science and Applications Division (MSAD) programs at NASA Headquarters. The refurbishment and reflight program is being managed by the Marshall Space Flight Center (MSFC) in Huntsville, Alabama. Funding and program support for the CGF project is provided to MSFC by the office of Life and Microgravity Sciences and Applications at NASA Headquarters. This paper presents an overview of the CGF system configuration for the USML-2 mission, and provides a brief description of the planned on-orbit experiment operation.

Srinivas, R.↗

NASA NTRS2016

The Zero Boil-Off Tank Experiment Ground Testing and Verification of Fluid and Thermal Performance

The Zero Boil-Off Technology (ZBOT) Experiment involves performing a small scale International Space Station (ISS) experiment to study tank pressurization and pressure control in microgravity. The ZBOT experiment consists of a vacuum jacketed test tank filled with an inert fluorocarbon simulant liquid. Heaters and thermo-electric coolers are used in conjunction with an axial jet mixer flow loop to study a range of thermal conditions within the tank. The objective is to provide a high quality database of low gravity fluid motions and thermal transients which will be used to validate Computational Fluid Dynamic (CFD) modeling. This CFD can then be used in turn to predict behavior in larger systems with cryogens. This paper will discuss the work that has been done to demonstrate that the ZBOT experiment is capable of performing the functions required to produce a meaningful and accurate results, prior to its launch to the International Space Station. Main systems discussed are expected to include the thermal control system, the optical imaging system, and the tank filling system.This work is sponsored by NASAs Human Exploration Mission Directorates Physical Sciences Research program.

Fluid management↗

NASA NTRS1990

A hydroponic design for microgravity and gravity installations

A hydroponic system is presented that is designed for use in microgravity or gravity experiments. The system uses a sponge-like growing medium installed in tubular modules. The modules contain the plant roots and manage the flow of the nutrient solution. The physical design and materials considerations are discussed, as are modifications of the basic design for use in microgravity or gravity experiments. The major external environmental requirements are also presented.

Fielder, Judith↗

NASA NTRS1989

Lignification in young plant seedlings grown on earth and aboard the Space Shuttle

The Space Shuttle era has provided an opportunity for investigators to conduct experiments in a microgravity environment. Two Shuttle flights, STS-3 and STS-51F, each contained an experiment designed principally to determine whether young plant seedlings exposed to microgravity had reduced lignin content in comparison to seedlings grown at one gravity. Three different plant species, pine, oats, and mung beans, were exposed for eight days to the microgravity environment of the Shuttle. The lignin content of in-flight seedlings was less than the control seedlings in all seven sets of seedlings included in these two experiments. In five sets of seedlings, the reduction in lignin content in flight seedlings ranged from 6 to 24 percent and was statistically significant. In addition, the activity of two enzymes involved in lignin synthesis, phenylalanine ammonia lyase and peroxidase, were significantly reduced in pine seedlings. It was therefore concluded that microgravity, as perceived by young plant seedlings, results in reduced lignin synthesis.

Cowles, Joe R.↗

NASA NTRS1998

Experiment 2: Vapor Transport Crystal Growth of Mercury Cadmium Telluride in Microgravity- USML-2

The new epitaxial growth experiments of Hg(l-x)Cd(x)Te on (100) CdTe substrates by chemical vapor transport (CVT), using HgI2 as a transport agent, were performed in the transient growth regime of this ternary, heteroepitaxial system at normal and reduced gravity during the USML-2 flight. The surface and interface morphology, the compositional and structural uniformity, and carrier mobility of the epitaxial layer and islands grown in microgravity are measurably improved relative to ground specimens. These observations demonstrate the effects of convective flow on the transport, deposition, and growth processes of this solid-vapor system even in the transient growth regime. The properties of the Hg(l-x)Cd(x)Te layer grown in a microgravity environment compare quite favorably to those of layers obtained by other techniques.

Wiedemeier, H.↗

NASA NTRS2000

ISS Microgravity Environment Monitoring System (MEMS): System Design - Part 1

The Principal Investigator Microgravity Services project at the NASA Glenn Research center supports Principal Investigators of the microgravity science community as they evaluate the effects of acceleration on their experiments. The Principal Investigator Microgravity Services' primary responsibility is to support NASA sponsored investigators in the area of acceleration data analysis, interpretation and the monitoring of the microgravity environment on-board various carriers. The microgravity environment is a rich and very complex dynamic one. It is subject to quasi-steady accelerations, higher frequency acceleration, and transient disturbances. With the advent of the International Space Station operation, a significant amount of data is expected to be downlinked and processed for both the space station microgravity environment characterization (verification) and scientific experiments. Therefore, to help principal investigator teams monitor the microgravity environment on-board the International Space Station in order to avoid negative impact on their experiment, when possible, the NASA Glenn Principal Investigator Microgravity Services project is currently developing an artificial intelligence monitoring system, which will notify the principal investigator teams in near real time of any change in the microgravity environment susceptible to affect their experiments.

Jules, Kenol↗

NASA NTRS1995

Low velocity opposed-flow frame spread in a transport-controlled environment DARTFire

The overall objectives of the DARTFire project are to uncover the underlying physics and increase understanding of the mechanisms that cause flames to propagate over solid fuels against a low velocity of oxidizer flow in a low-gravity environment. Specific objectives are (1) to analyze experimentally observed flame shapes, measured gas-phase field variables, spread rates, radiative characteristics, and solid-phase regression rates for comparison with previously developed model prediction capability that will be continually extended, and (2) to investigate the transition from ignition to either flame propagation or extinction in order to determine the characteristics of those environments that lead to flame evolution. To meet the objectives, a series of sounding rocket experiments has been designed to exercise several of the dimensional, controllable variables that affect the flame spread process over PMMA in microgravity, i.e., the opposing flow velocity (1-20 cm/s), the external radiant flux directed to the fuel surface (0-2 W/cm(exp 2)), and the oxygen concentration of the environment (35-70%). Because radiative heat transfer is critical to these microgravity flame spread experiments, radiant heating is imposed, and radiant heat loss will be measured. These are the first attempts at such an experimental control and measurement in microgravity. Other firsts associated with the experiment are (1) the control of the low velocity, opposed flow, which is of the same order as diffusive velocities and Stefan flows; (2) state-of-the-art quantitative flame imaging for species-specific emissions (both infrared and ultraviolet) in addition to novel intensified array imaging to obtain a color image of the very dim, low-gravity flames.

West, Jeff↗

NASA NTRS1998

Fluids and Combustion Facility: Fluids Integrated Rack

The Fluids Integrated Rack (FIR) is a modular, multi-user facility to accommodate a wide variety of microgravity fluid physics science experiments on-board the US Laboratory Module of the International Space Station (ISS). The FIR is one of three racks comprising the Fluids and Combustion Facility (FCF). The FCF is being designed to increase the amount and quality of scientific data and decrease the development cost of an individual experiment relative to the era of Space Shuttle experiments. The unique, long-term, microgravity environment and long operational times on the ISS will offer experimenters the opportunity to modify experiment parameters based on their findings similar to what can be accomplished in ground laboratories. The FIR concept has evolved over time to provide a flexible, 'optics bench' approach to meet the wide variety of anticipated research needs. The FIR's system architecture presented is designed to meet the needs of the fluid physics community while operating within the constraints of the available ISS resources.

Corban, Robert R.↗

NASA NTRS2002

Optimal Control Design using an H(sub 2) Method for the Glovebox Integrated Microgravity Isolation Technology (G-Limit)

The acceleration environment on the International Space Station (ISS) will likely exceed the requirements of many micro-gravity experiments. The Glovebox Integrated Microgravity Isolation Technology (g-LIMIT) is being built by the NASA Marshall Space Flight Center to attenuate the nominal acceleration environment and provide some isolation for microgravity science experiments. G-LIMIT uses Lorentz (voice-coil) magnetic actuators to isolate a platform for mounting science payloads from the nominal acceleration environment. The system utilizes payload acceleration, relative position, and relative orientation measurements in a feedback controller to accomplish the vibration isolation task. The controller provides current commands to six magnetic actuators, producing the required experiment isolation from the ISS acceleration environment. This paper presents the development of a candidate control law to meet the acceleration attenuation requirements for the g-LIMIT experiment platform. The controller design is developed using linear optimal control techniques for frequency-weighted H(sub 2) norms. Comparison of the performance and robustness to plant uncertainty for this control design approach is included in the discussion.

Calhoun, Philip C.↗

NASA NTRSDate not supplied

The Zero-Boil-Off Tank Experiment: the Effects of Non-Condensable Gases on Pressurization and Pressure Control of Propellant Tanks in Microgravity

Introduction Integral to all phases of NASA’s projected planetary expeditions is affordable and reliable cryogenic fluid storage for use in propellant or life support systems. It is greatly advantageous to develop innovative vent-less pressure control designs based on cooling/mixing of the bulk tank fluid to allow storage of the cryogenic fluid with zero or reduced boil-off. The presence of noncondensable gases, can interfere with the condensation at the interface impacting tank pressure control during subcooled jet mixing especially in microgravity. The Zero-Boil-Off Tank (ZBOT) Experiments are a series of small-scale experiments aboard the International Space Station (ISS) that use a transparent volatile simulant fluid in a transparent sealed tank to delineate various fundamental fluid flow, heat and mass transport, and phase change phenomena associated with storage tank pressurization and pressure control in microgravity. The ZBOT-1 experiment was performed on the ISS 2017-2018 timeframe and collected data to validate a state-of-the-art CFD model for tank pressurization and pressure control for a pure system. The ZBOT-NC Experiment is the second experiment in the series to be performed on the International Space Station (ISS) in 2025. Its goal is to investigate the effects of noncondensable gases on interfacial evaporation and condensation during self -pressurization and jet-mixing pressure control in microgravity for a two-component system. Materials & Methods In this work, we will describe the detailed features of the ZBOT-NC experimental hardware and Diagnostics that includes nonintrusive Quantum Dot Thermometry (QDT) for whole field temperature measurement. All microgravity pressurization and pressure control tests will be performed for both the pure and the two-components systems with Xenon and Neon as the two noncondensable gases spanning small and large molecular weights and sizes. The two-phase CFD model that is developed as part of the project will be also presented and discussed. Results Ground-based pressurization and jet mixing experiments and CFD simulation results are compared to each other to validate both the fidelity of the CFD model predictions and the accuracy of the QDT measurement. Model simulations for noncondensable gas effects will also be compared against large Cryogenic LH2-GHe experiments to indicate the noncondensable gas effects on tank pressure control during jet mixing in 1G. Finally, CFD results will be presented to predict the effects of the noncondensable gas during subcooled jet mixing during the ZBOT-NC in advance of the microgravity experiment in 2015.

Evaporation Condensation↗