Microgravity Field Research Articles

Shapes of chondrules determined from the petrofabric of the CR2 chondrite NWA 801

AbstractThe approximately spherical shapes of chondrules has long been attributed to surface tension acting on ~1 mm melt droplets that formed and cooled in the microgravity field of the solar nebula. However, chondrule shapes commonly depart significantly from spherical. In this study, 109 chondrules in a sample of CR2 chondrite NWA 801 were imaged by X‐ray computed tomography and best‐fitted to ellipsoids. The analysis confirms that many chondrules are indeed not spherical, and also that the chondrules’ collective shape fabric records a definite 13% compaction in the host meteorite. Dehydration of phyllosilicates within chondrules may account for that strain. However, retro‐deforming all chondrules shows that a large majority were already far from spherical prior to accretion. Possible models for these initial shapes include prior deformation of individual chondrules in earlier hosts, and, as suggested by previous authors, rotation of chondrules as they were solidifying, and/or “streaming” of molten chondrules by their differential velocities with their gaseous hosts after melting. More in situ 3‐D work such as this study on a variety of unequilibrated chondrites, combined with detailed structural petrography, should help further constrain these models and refine our understanding of chondrite formation.

Placental Growth Factor Levels in Populations with High Versus Low Risk for Cardiovascular Disease and Stressful Physiological Environments such as Microgravity: A Pilot Study

This pilot study compared placental growth factor (PIGF) levels in populations with high versus low risk for cardiovascular disease. Previous experiments from our laboratory (Sundaresan et al. 2005, 2009) revealed that the angiogenic factor PIGF was up regulated in modeled microgravity conditions in human lymphocytes leading to possible atherogenesis and pathogenesis in microgravity. Since the findings came from microgravity analog experiments, there is a strong link to its usefulness in the microgravity field as a biomarker. It is important to understand, that these findings came from both studies on expression levels of this cardiovascular marker in human lymphocytes in microgravity (in vitro microgravity analog), and a follow up gene expression study in hind limb suspended mice (in vivo microgravity analog). The relevance is enhanced because in life on earth, PIGF is an inflammatory biomarker for cardiovascular disease. Studies on the levels of PIGF would help to reduce the risk and prevention of heart failures in astronauts. If we can use this marker to predict and reduce the risk of cardiac events in astronauts and pilots, it would significantly help aerospace medicine operations. The investigations here confirmed that in a cardiovascular stressed population such as coronary artery disease (CAD) and acute coronary syndrome (ACS) patients, PIGF could be overexpressed. We desired to re-evaluate this marker in patients with cardiovascular disease in our own study. PIGF is a marker of inflammation and a predictor of short-term and long-term adverse outcome in ACS. In addition, elevated PIGF levels may be associated with increased risk for CAD.PIGF levels were determined in thirty-one patients undergoing cardiovascular catheterization for reasons other than ACS and in thirty-three low-risk asymptomatic subjects. Additional data on traditional cardiovascular risk factors for both populations were also compiled and compared. We found that PIGF levels were significantly higher in the high-risk population as compared to low-risk population. Also we were able to ascertain that PIGF levels were inversely correlated with HDL-cholesterol but directly correlated with the triglyceride levels. With further validation, PIGF may prove a useful addition to the armamentarium of noninvasive biomarkers for cardiovascular disease including a new area of stressful physiological conditions such as microgravity.

Experimental and Analytical Techniques for Studying ZBLAN Crystallization in Microgravity

One of the promising new areas of materials research is in the field of microgravity. Microgravity experimentation enables new materials to be developed and traditional materials to be improved, which cannot be completed under terrestrial conditions. Recent experiments on ZBLAN (ZrF4–BaF2–LaF3–AlF3 –NaF) glass have shown that, when heated, there is a crystallization dependency on gravity. This crystallization dependency limits the optical transmissibility of this material, due to crystallites forming during the fiber drawing process. ZBLAN glass has the theoretical potential for optical transmission in the range of 0.3 –7 μm, which would facilitate much needed mid-infrared (IR) fiber technology. Past researchers have completed ZBLAN crystallizationmicrogravity experiments, with limited details on the experimental technique and analysis methods. This study demonstrates an alternative experimental technique for ZBLAN microgravity testing and postprocessing techniques that reveal crystallinity in the sample.

Using Parabolic Flights to Examine Quantitatively the Stability of Liquid Bridges under Varying Total Body Force

Liquid bridges were flown aboard a Boeing 727-200 aircraft in a series of parabolic arcs that produced multiple periods of microgravity. During the microgravity portion of each arc, geff, the effective total body acceleration due to external forces became negligibly small so that cylindrical liquid bridges could be suspended across two coaxial support posts. Near the bottom of each arc, geff slowly increased to a maximum of 1.84g, causing the liquid bridges to deform and in some cases collapse. Although the physics of liquid bridges subject to varying total body force is well-established and has been analyzed extensively both theoretically and experimentally, specific hardware was designed to vary geff in a precise way that overcomes the gravity-related limitations and high g-jitter associated with parabolic flights. Bridge-stability was examined for axial and lateral orientations with respect to geff by measuring the slenderness ratio as a function of Bond number at the instant of bridge collapse. Results exhibit remarkable agreement with theory as well as with the experimental results obtained in a magnetic levitation-based experiment. The parabolic flight method offers technical originality and provides experimental insights for researchers in the microgravity field. Here we present hardware development, experimental considerations, and results, and demonstrate that parabolic flight is a viable alternative to extant techniques for quantitative experiments on fluids.

Density-thermal dependence of sedimentary associations calls to reinterpreting detailed gravity surveys

<p>The modern gravimetric equipment allows to register very small effects of gravity field changes and can be applied solving different geological, geophysical and environmental problems. However, sometimes insufficient calculation of various kinds of geological noise complicates effective application of detailed gravity field analysis. One of such factors is the temperature regime over and outside different buried objects of investigation. In this paper temperature changes in a subvertical zone over a hydrocarbon deposit and outside its contour are analyzed. The integrated density change and corresponding gravity effects are calculated for the Muradkhanly oil deposit situated within the south-east part of the Middle Kura Depression (central Azerbaijan). Calculation of these effects on the basis of density- temperature data correlation analysis could significantly improve the microgravity field examination over the hydrocarbon deposits. The similar correction procedure may be applied also over underground water horizons and some environmental targets.</p>

Utilization of Microgravity Field for Combustion Research

Utilization of Microgravity Field for Combustion Research

Numerical simulation of InGaSb crystal growth by temperature gradient method under normal- and micro-gravity fields

InxGa1−xSb single crystals are to be grown by using a GaSb/InSb/GaSb-sandwich system onboard at the International Space Station (ISS). In order to have a better understanding for the transport phenomena occurring in the melt (solution) of this sandwich system, the dissolution and the growth processes were numerically simulated under a microgravity level of the ISS. Simulations were also performed under the gravitational field of Earth (1g) for comparison. The simulation domain includes the In–Ga–Sb solution (liquid phase) for fluid flow, and heat and mass transfer, and the crucible ampoule (solid phase) for heat transfer. Heat and mass balances were also used at the crystal–solution interfaces to examine the dissolution and growth processes globally. Simulation results showed that, at 1g, dissolution of the GaSb seed was enhanced due to the contribution of solutal natural convection, and the solution saturated faster compared with that under microgravity. Diffusion during growth was dominant at the both gravity levels. The GaSb concentration in the solution under microgravity was slightly affected by the temperature distribution in the ampoule.

Numerical Study of Transport Phenomena During Bulk Single Crystal Growth under Microgravity Fields

Numerical Study of Transport Phenomena During Bulk Single Crystal Growth under Microgravity Fields

Viscous Fingering through Two Dimensional Porous Layer in Microgravity Environment

Slow fluid-fluid displacement in a porous medium under the influence of real microgravity field is going to reveal important fluid physics associated with hydrology, chemical engineering and the physics of disordered media. Most systems of practical importance include fluids of different densities. Therefore it is important to study the effect of gravity on the front/displacement-structure (fingering: due to the nonlinear interactions among viscous, capillary and gravitational forces). CFD(Computational Fluid Dynamics) analysis glycerin/water mixture through two dimensional single layer aniso-tropic artificial porous layer have been performed in ground level condition as well as microgravity modifying the body force source term in the momentum equation through UDF(user defined functions) written in C. Ground level experiment to capture fingering has also been performed to validate the CFD results. Fingering structures in the microgravity and g-jitter conditions have been predicted using the validated CFD model.

Realization of modes of satellite attitude motion with a small level of microaccelerations using electromechanical executive devices

Quasi-static microaccelerations are estimated for a satellite specially designed to perform space experiments in the field of microgravity. Three modes of attitude motion of the spacecraft are considered: passive gravitational orientation, orbital orientation, and semi-passive gravitational orientation. In these modes the lengthwise axis of the satellite is directed along the local vertical, while solar arrays lie in the orbit plane. The second and third modes are maintained using electromechanical executive devices: flywheel engines or gyrodynes. Estimations of residual microaccelerations are performed with the help of mathematical modeling of satellite’s attitude motion under the action of gravitational and aerodynamic moments, as well as the moment produced by the gyro system. It is demonstrated that all modes ensure rather low level of quasi-static microaccelerations on the satellite and provide for a fairly narrow region of variation for the vector of residual microacceleration. The semi-passive gravitational orientation ensures also a limited proper angular momentum of the gyro system.

610 微小重力場における定在音場中の局所加熱/冷却により生じる二次流れの特性(OS9-1 微小重力を利用した燃焼の基礎研究I,OS9 微小重力を利用した燃焼の基礎研究)

610 微小重力場における定在音場中の局所加熱/冷却により生じる二次流れの特性(OS9-1 微小重力を利用した燃焼の基礎研究I,OS9 微小重力を利用した燃焼の基礎研究)

Effects of gravity on the electrodeposition and characterization of nickel foils

The effects of gravity on nickel electrodeposition, the morphology and mechanical properties of deposits were studied in a super gravity field. Predictions in a microgravity field were also presented based on the obtained experimental tendency. Linear sweep voltammetry reveals that the nickel electrodeposition process is enhanced by increasing the gravity coefficient (G). The limiting current density changes from 10.2 to 293.0 mA·cm−2 with the increase of the G value from 10−4 to 354. The morphology of deposits was analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The images show that the morphology deposited in the super gravity field has finer grain sizes and denser and smoother surfaces. The roughness reduces from 48.3 to 4.9 nm with the increase of the G value from 10−4 to 354. Meanwhile, mechanical tests indicate that the mechanical properties of nickel foils are greatly improved due to introducing a super gravity field during electrodeposition.

二次元密度成層界面への二次元渦対衝突過程におけるバロクリニックトルク生成の微小重力実験(熱工学,内燃機関,動力など)

The baroclinic torque, which is generated by density gradient and pressure gradient, is studied with a PIV (Particle Image Velocimetry) method. In this work, the two dimensional density gradient is formed in binary density planar boundary stratified by the gravity. The pressure gradient is introduced with penetration of a pair of two dimensional vortices into the density boundary. A series of the experiments is carried out in micro-gravity field so as to allow buoyancy-free condition. The results show that the baroclinic torque is induced on the boundary of binary density field by approaching the pair vortex to the boundary. This result indicates the possibility of numerical analysis where the baroclinic torque is introduced precisely by the discrete vortex method as one of Lagrange method at inhomogeneous density flow field.

Near-field instability of variable property jet in normal gravity and microgravity fields

The near-field instability of variable property jets of air, CO2, and He, issued into the ambient air, has been investigated experimentally within normal gravity and microgravity fields. The density ratio to the ambient air is unity for air jets, more than unity (1.53) for CO2 jets, and less than unity (0.14) for He jets, respectively. The ratio of kinematic viscosity to the ambient air is unity for air jets, less than unity for CO2 jets (0.53), and more than unity for He jets (7.75), respectively. The jet velocity is varied from 0.4 to 1.8 m/s and then the jet Reynolds number varies from 60 for Helium jet to 2,000 for CO2 jet, while the Richardson number varies from negative to positive values. The motion of the jet is visualized using a laser tomographic method and recorded by a high-speed digital video camera with 250 frames/s. The result shows that the instability of the jet is intensified when Re > 800 while it is weakened at Re < 800 at the microgravity field, indicating that the viscosity plays an important role in weakening the instability. Under a normal gravity field, the buoyancy also becomes important. In order to quantify the instability criteria, the quantity of the instability is introduced, which consists of the Kelvin–Helmholtz instability, buoyancy effect and viscous effect. When the ratio of the sum of Kelvin–Helmholtz and buoyancy forces to viscous force exceeds a certain value, around 12 in the present study, the jet becomes unstable even when Re < 800. These results reveal that the instability of variable property jets is influenced by the Kelvin–Helmholtz instability, the viscous effect and the buoyancy effect.

A141 微小重力場におけるポリエチレンフィルムの溶解・燃焼挙動(燃焼科学と技術の新展開IV)

The objective of this research is to investigate the melting and the burning characteristics of polyethylene film in microgravity field. This experiment was conducted using Drop Experiment Facility in Micro-gravity Laboratory of Japan. The flame and the droplet became spherical shape in micro gravity field. For 850K and 900K temperature in the furnace, the droplet diameter first increased and then decreased due to occurrence of expansion and vaporization before polyethylene film ignited. After ignition, droplet diameter suddenly increased, and then decreased. For the 950K temperature in the furnace, the droplet diameter increased gradually until polyethylene film ignited. After ignition, droplet diameter, d, suddenly increased, and then d^2 decreased lineally, showing d^2 low.

Study of the factors affecting the karst volume assessment in the Dead Sea sinkhole problem using microgravity field analysis and 3-D modeling

Abstract. Thousands of sinkholes have appeared in the Dead Sea (DS) coastal area in Israel and Jordan during two last decades. The sinkhole development is recently associated with the buried evaporation karst at the depth of 25–50 m from earth's surface caused by the drop of the DS level at the rate of 0.8–1.0 m/yr. Drop in the Dead Sea level has changed hydrogeological conditions in the subsurface and caused surface to collapse. The pre-existing cavern was detected using microgravity mapping in the Nahal Hever South site where seven sinkholes of 1–2 m diameter had been opened. About 5000 gravity stations were observed in the area of 200×200 m2 by the use of Scintrex CG-3M AutoGrav gravimeter. Besides the conventional set of corrections applied in microgravity investigations, a correction for a strong gravity horizontal gradient (DS Transform Zone negative gravity anomaly influence) was inserted. As a result, residual gravity anomaly of –(0.08÷0.14) mGal was revealed. The gravity field analysis was supported by resistivity measurements. We applied the Emigma 7.8 gravity software to create the 3-D physical-geological models of the sinkholes development area. The modeling was confirmed by application of the GSFC program developed especially for 3-D combined gravity-magnetic modeling in complicated environments. Computed numerous gravity models verified an effective applicability of the microgravity technology for detection of karst cavities and estimation of their physical-geological parameters. A volume of the karst was approximately estimated as 35 000 m3. The visual analysis of large sinkhole clusters have been forming at the microgravity anomaly site, confirmed the results of microgravity mapping and 3-D modeling.

Numerical Simulation of Thermo-Solutal Marangoni Convection in the Floating-Zone under Microgravity Fields

Numerical Simulation of Thermo-Solutal Marangoni Convection in the Floating-Zone under Microgravity Fields

Thermal convection in square porous cavity under transverse oscillatory micro gravity field

Two-dimensional thermal convection in saturated square porous cavity under transverse sinusoidal micro-gravity field, has been analyzed by solving mass and transient momentum and energy balance equations, using Darcy’s law and Boussinesq’s approximation. Isothermal boundary conditions are considered at the two vertical walls but at different temperatures and other two horizontal walls are adiabatic. Average Nusselt numbers are presented as a function of Darcy-Rayleigh number (Ramod) and dimensionless time. Thermally convective, transient nature of the flow field has also been presented for different Darcy-Rayleigh number (Ramod).

4D reservoir volumetrics: a case study over the Izaute gas storage facility

Dr Duncan Bate (ARK Geophysics) presents a recent oil company sponsored case study in France pointing to the value of 4D microgravity modelling as a cost-effective and unintrusive way of enhancing reservoir information. Measuring the Earth’s gravitational field as a means to mapping subsurface density distributions has been an exploration technique for decades. Gravitational anomalies may be related to subsurface geological structures and thus indicate features including faults, intrusives, and salt structures. High spatial resolution gravity data (as acquired with 3D seismic surveys) may be used in combination with 3D modelling to help define end member salt volumes in seismic imaging processes such as pre-stack depth migration (PSDM). The measurement of the time varying (4D) gravity field as a method of observing subsurface fluid flow in a hydrocarbon reservoir is a more recent application of gravity data. ARK Geophysics (ARK) conducted a time-lapse microgravity field trial over the Izaute gas storage reservoir in the Gascoigne district of South-Western France approximately 60 km north of Pau, between January 2003 and June 2004. The reservoir is operated by Total Infrastructure Gaz France (TIGF). The project was coordinated by ITF and funded by Statoil, Shell, and Total. The reservoir is a domestic gas storage buffer – filled throughout the summer months and depleted during the winter. The objective of this trial was to investigate whether time changes in the observed gravity field could practically be measured and if so, whether the observations correlated to known changes in gas stock levels. Twelve repeat gravity surveys were performed (each comprising over 200 stations) and two continuous gravity meters were employed. Overall the measured time-lapse gravity data correlate well with the predicted gravity changes from the reservoir model. Any observed differences between the predicted gravitational response of the reservoir model and the measured time varying gravity field requires further investigation. Sources of such observed discrepancies include system noise but also geological information that may not have been captured in the reservoir model such as reservoir compartmentalization, porosity, and permeability differentials as well as unmapped thief zones. The continuous data recorded over the reservoir show a good correlation with the reservoir gas pressure data. The aim of this study was to assess whether the time varying gravity field generated by a propagating density interface (e.g. oil-water or gas-water contact) can be measured by currently available cost-effective instrumentation. A two-fold approach was employed, utilizing time-lapse (or dynamic) and continuous gravity acquisition techniques. A dynamic gravity project comprises repeat static gravity surveys and is sometimes referred to as time-lapse or 4D. Workers in this field have successfully applied this technique to hydrothermal energy exploration (Hallinan et al., 1989; Allis et al., 1986) and hazard monitoring (Rymer &amp; Brown, 1986; Yokoyama, 1989). A continuous gravity survey involves recording the variations in gravity continuously over a period of time. This technique has previously been used for long term studies of earth tides and volcano monitoring. There are several designs of gravity meter that can measure to the required accuracy for this project. The LaCoste and Romberg G and D meters with Aliod electrostatic feedback nulling system were used. This system has a range of approximately 100 mgal (+/-50) with a resolution of 0.01, or 0.001 mgal depending on which version is fitted. The Izaute, and its neighbouring Lussagnet, gas storage facilities have been created from porous submolassic sand reservoirs in the upper section of a vast multi-layer reservoir that contains the ‘inframolassic aquifer’ stretching from the Pyrenees to north of Bordeaux. The Izaute reservoir is formed by a gently plunging anticline, with an overburden of approximately 500 m. The reservoir thickness ranges from 50 to 80 m, has a porosity of between 25% and 35% and a permeability of between 6 and 20 Darcys. Gas is injected in the summer months (May to October) and recovered in the winter months (November to April). The total seasonal variation in the depth to the gas-water contact is 24 m.

Effect of magnetic field on metallurgical structure of magnetostrictive alloys solidified unidirectionally in microgravity

TbFe2 alloy solidification experiments were conducted in a static magnetic field in microgravity using a 10 m drop tower. When TbFe2 melt was solidified in a magnetic field from 0 to 0.12T in microgravity, a [111] crystallographic alignment dominated with an increased magnetic field, but the planar macrostructure was random. The magnetostrictive constant of TbFe2 solidified in magnetic field of 0.12T in microgravity was 2000 ppm at the external 1. 6T magnetic field. When TbFe2 melt was solidified unidirectionally in a 0. 1 T magnetic field in microgravity, a [111] crystallographic alignment dominated, and the planar structure grew and oriented along the solidification direction. The magnetostrictive constant of TbFe2 solidified unidirectionally in a 0. 1 T magnetic field in microgravity was 4500 ppm at the external 1. 6T static magnetic field. For all solidification in normal gravity, the maximum magnetostrictive constant remained at 2000 ppm at the external 1. 6T static magnetic field. TbFe2 crystals grew predominantly along the same direction as the magnetic field, and the planar structure oriented along the solidification direction in microgravity.