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| Microgravity Science Glovebox (MGBX) |
| SpaceHab |
| Prime: Chiaki Mukai | Principal Investigator: see individual experiments |
| Backup: Pedro Duque | Project Scientist: Dr. Donald A. Reiss, Space Sciences Laboratory, Marshall Space Flight Center, Huntsville, Ala. |
| Overview |
| Three investigations will be performed in MGBX during the STS-95 mission: Internal Flows in a Free Drop (IFFD), Colloidal Disorder-Order Transition (CDOT), and Structural Studies of Colloidal Suspensions (CGEL). Internal Flows in a Free Drop (IFFD) Surface tension is the property of a liquid's surface that, like a skin, holds it together. Investigators want to measure the internal fluid flows induced by the acoustic field and areas of different temperature on the surfaces of the drops. Researchers want to measure the surface tension of the drops. This investigation uses acoustic energy or sound to remotely control the position and motion of free-floating drops of liquid in the experiment facility. Findings may have applications for improving manufacturing processes on Earth and in space by providing new techniques for accurately measuring the properties of a liquid. This will allow manufacturers to better predict the behavior of a liquid during processing and, consequently, control the process to produce materials with more desirable properties. Results of this experiment may be relevant to many processes in chemical manufacturing industries, such as petroleum, cosmetics, and food sciences. Free, single drops will be deployed in the MGBX, then positioned and manipulated using sound waves. Droplets will be heated unevenly to cause fluid flow within the droplets. Tracer particles in the drops will allow researchers to see and record the movement of the drops and internal flows at various temperatures. The principal investigator is Dr. S.S. Sadhal, Jet Propulsion Laboratory, Pasadena, Calif. Colloidal Disorder-Order Transition (CDOT) Everything in the universe is made up of atoms. All physical properties of matter, such as weight, hardness, and color, are determined by the kinds of atoms present in a substance, the way they interact with each other, and the type of arrangements they form. The size of atoms and the complex ways groups of atoms organize themselves to form various states of matter make them very difficult to study. One way to overcome these problems is by studying systems of simple, larger particles that behave in similar ways. The Colloidal Disorder-Order Transition experiment will test fundamental theories that describe atomic behavior. Colloids are systems of fine particles suspended in fluid. Milk, orange juice, and paint are some common examples. The experiment uses colloidal suspensions of uniformly sized microscopic solid plastic spheres as a model of atomic interactions. On Earth, gravity causes the denser particles in a colloidal suspension to settle to the bottom, which is why some colloids, like orange juice and paint, must be stirred before use. Microgravity enables scientists to study colloids because the effects of density differences between particles and their surrounding fluids are decreased, thus eliminating settling and maintaining an even distribution of particles in the fluid. During the STS-95 mission, researchers will use colloids to learn more about how the organization of atoms changes as they form into orderly solid structures. Researchers are using colloidal hard spheres suspended in liquid in varying concentrations to model this behavior. In samples with a certain level of concentration of hard spheres, crystal-like structures form. The behavior of these systems is similar to the changes in atomic structure that take place in the transition from liquid to solid, such as when water freezes and becomes ice. Initially, atoms in the water are randomly distributed. As the water freezes, atoms organize themselves into crystalline arrangements. Experiment test samples will contain plastic spheres that are about one-tenth of the thickness of a human hair in diameter. In orbit, the samples will be allowed to sit for several days while the spheres organize themselves. The spheres, like atoms, will settle into an arrangement that gives each sphere the most space. A sample with a low concentration of spheres is expected to maintain fluid movement, like atoms in a liquid. Samples with higher concentration levels of hard spheres should form crystal-like structures. In samples with a very high concentration of spheres, no crystals will form. This last behavior is similar to the solidification of liquids into glass materials in which the atoms move so slowly that it takes millions of years for them to organize into crystalline structures. Researchers will use laser light directed at the colloidal samples to study the arrangements of spheres that form in the samples. The laser light will be scattered off the surface of the structures, similar to the way sunlight "sparkles" on snow flakes. The scattered light will reveal information about the pattern the structures have taken. With this information, scientists will gain insight into the validity of current theories of atomic behavior and will begin to answer questions of condensed matter physics regarding the transition between liquid and solid phases. The principal investigator is Paul Chaikin, Princeton University, Princeton, N.J. Structural Studies of Colloidal Suspensions (CGEL) Understanding the structures of colloids may allow scientists to manipulate their physical properties, a process called "colloidal engineering," for the manufacture of novel materials and products. Colloid research may even improve the processing of known products for the enhancement of desirable properties. CFGEL will further colloid research through the study of three kinds of colloids: binary alloy colloids, a colloid possessing particles of different sizes; colloid polymers, a colloid that in addition to possessing spherical particles also possesses long, chain-like molecules; and fractal colloid aggregates, colloids possessing repeating structural patterns or networks. In orbit, all three types of colloid samples will be mixed to distribute the suspended particles and then allowed to sit for several days. During this interval, particles in the samples will organize themselves in crystal-like arrangements. Laser light will be used to gather structural information about the samples. The light will be directed at the samples and scatter as it is reflected off the surface of the crystalline structures, revealing the placement of particles in the colloids. Observations of the properties resulting from particular structures can then be made. With this information, researchers will develop models to predict the structures and properties of different kinds of colloids. The ability to predict a material's characteristics could result in decreased product development time and may lead to more efficient manufacturing. Industries using semiconductors, electro-optics, ceramics, and composites are among those that may benefit from colloid research. The principal investigator is David Weitz, University of Pennsylvania, Philadelphia, Penn. |
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| History/Background |
| MGBX offers scientists the capability to conduct investigations, test science procedures, and develop new technologies in microgravity. The glovebox provides an enclosed work area about the size of a microwave for these small-scale investigations. MGBX also provides a work area with two levels of containment--physical barrier and negative pressure--between the crew working space and the microgravity investigations. The glovebox provides a sealable, controlled workspace for performing investigations that require hands-on attention, while protecting the astronaut researcher and the rest of the crew. Fluids, powders, bioproducts, and irritants are among the materials that may be used by researchers during their investigations. It is a facility designed to support investigations and demonstrations in five microgravity research disciplines: materials science, biotechnology, combustion science, fluid dynamics, and fundamental physics. Within MGBX, while investigations are being conducted, three video cameras can record the development of the investigation. These data may be transmitted to the principal investigators on Earth, allowing them to instruct the crew to make experimental adjustments if necessary. The Microgravity Glovebox Flight Program is part of the Microgravity Research Program at Marshall Space Flight Center in Huntsville, Ala. |
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| Benefits |
| Gravity dominates everything on Earth, from the way life has developed to the way materials interact. But aboard a spacecraft orbiting the Earth, the effects of gravity are barely felt. In this "microgravity environment," scientists can conduct experiments that are all but impossible to perform on Earth. In this virtual absence of gravity as we know it, space flight gives scientists a unique opportunity to study the states of matter (solids, liquids, and gases), and the forces and processes that affect them. |
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