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Physics of Hard Spheres (PHaSE)
What is really happening when water turns into ice? Well, nobody's absolutely sure. The physics of basic chemistry - liquid-to-solid phase transitions (and vice versa) - is obscured by the effects of gravity. However, phase trasitions can be studied by suspending very small - a millionth of a meter across- very hard spheres in a liquid. Called a "colloidal mixture," when sent into orbit aboard the shuttle (or better yet on the International Space Station), these suspended spheres, which only interact when they touch - like bowling balls - behave like growing crystals.
The system of hard-spheres is one of the simplest models that represents and reproduces the physical characteristics of real atomic systems. The thermodynamic properties of the hard-spheres depend on the geometry of how the spheres are packed together. These geometrical considerations are the basis of the melting transition for many liquids. Flying this experiment aboard the shuttle allows scientists to study the physics of these liquid-solid systems without the interference of gravity.
The PhaSE experiment was developed at NASA's Lewis Research Center. Principal investigator is Dr. Paul Chaikin, of Princeton University, NJ.
Figure at left shows how the hard spheres arrange themselves in the different phases and the concentrations at which they occur on Earth. Click picture for full diagram.
Plant Generic BioProcessing Apparatus (PGBA)
How well can plants grow in space? That's one of the things scientists who developed the PGBA wants to find out. A complete answer to that question may help solve a number of others, such as growing enough plants to live on in space, and making better pharmaceutical drugs. This experiment is being conducted to study how particular plant systems adapt to spaceflight, especially the production of the plants structural elements, secondary products that are often used as pharmaceuticals, and the alterations in sugars and starches.
The PGBA principal investigator is Dr. Louis Stodieck, at the University of Colorado, Boulder. The growth chamber, pictured at left from a May '96 flight n Spacehab, will be housed in the EXPRESS rack during the MSL-1 mission.
Capillary-driven Heat Transfer (CHT)
"What is this?" you may ask yourself. Well, it is not as complicated as you may think. Imagine filling your kitchen sink with hot water, then taking a sponge in your right hand and dipping the sponge halfway into the sink. Now, hold it there. What happens? The hot water is "soaked-up" by the sponge, and if you hold your hand there long enough, eventually your fingers will feel the hot water. Heat has been transferred from the water in the sink to your fingers by the capillary action of the sponge, which in this simiple example, actually was strong enough to move the water against the force of gravity.
In spaceflight, capillary-pumped loops are used to transfer heat away from electrical devices to space radiators. These usually involve the evaporation and re-condensation of a fluid, making things more complicated that our simple example above. For a variety of reasons, these devices are not always totally reliable. However, they are very attractive because they require no power to operate, and are very economical in terms of weight, an important consideration in satellite design. The CHT experiment will help to give us a better understanding of the mechanisms behind the unstable operation and occasional failure of these devices. This experiment will be carried out using the Glovebox.
The picture at left is the CHT apparatus on MSL-1.
Deformation of a drop of
water using ultrasound.
BDND/ MSL-1 July 4, 1997.
Bubble and
Drop Nonlinear Dynamics (BDND)
Bubbles that form during the processing of materials can cause many complications in a variety of manufacturing processes. The Bubble and Drop Nonlinear Dynamics (BDND) experiment will explore the oscillation characteristics of bubbles when surface tension is a dominating force. Scientists will also explore the possible uses of ultrasound to manipulate bubbles in microgravity. This experiment will be carried out using the Glovebox.
Internal
Flows in a Free Drop (IFFD)
How do you position liquids in microgravity? Imagine, for example, how difficult the simple task of pouring yourself a glass of milk would be without gravity? In less mundane situations, the positioning of liquids with acoustic (sound) energy is important when processing materials in the absence of a container, or when making non-contact measurements of the viscosity and surface tension of materials.
The IFFD experiment on MSL-1 will test current non-contact and remote manipulation techniques for controlling the position and motion of free liquids in microgravity, as well as try to perform the first measurement of thermocapillary flows in a totally free drop.
This experiment will be carried out using the Glovebox.
Microgravity
Measurements
Just saying you're weightless isn't good enough. The sophistication of the experiments aboard MSL-1 and other missions requires special equipment to measure accelerations and vibrations so scientists can tell later what was happening when they see interesting features in their samples. The Principal Investigator Microgravity Services (PIMS) project at NASA's Lewis Research Center will maintain near-real time data display of acceleration data for each of the experiment modules during the MSL-1 mission.
