Science à
la Carte Menu
In a good restaurant, the à la Carte menu offers choices that are just as appetizing as the specials of the day. If MSL-1 were a restaurant, the science choices from the à la Carte menu alone would make the mission five-star.
Studying the Transition From Liquid to Solid
- PHaSE
The arrangement of atoms in a solid, and how they get to be arranged in this way upon cooling from the liquid phase, is an area of great interest in materials science. The arrangement of atoms in a solid helps determine many of the properties of the solid, such as its strength, electrical conductivity, and flexibility.
The Physics of Hard Spheres Experiment (PHaSE) uses tiny hard spheres as a model to study the transition that actually takes place on the atomic level. In many cases, one can treat the atoms in a solid like tiny bowling-balls, or similar impenetrable hard spheres, that only interact with one another when actually touching. On MSL-1, we're not necessarily studying the hard spheres themselves, but using them as a substitute to study the atomic interactions they represent.
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.
The advantage of using hard spheres to study these processes is that they are easier to measure, observe, and manipulate than atoms themselves. However, the drawback is that gravity interacts much more profoundly with the hard-sphere model system than the actual atomic system. By flying this experiment aboard the shuttle, scientists can study the physics of these liquid-solid systems, using the easier representation of hard spheres, without the interference of gravity.
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.
Studying Plant Growth in Microgravity
NASA has performed many life-science or biological experiments aboard the space shuttle in the past, and MSL-1, although not primarily dedicated to these science areas, continues this program with the Astro/Plant Generic Bioprocessing Apparatus (Astro/PGBA).
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.
Picture shows the plants inside the PGBA growth chamber from Spacehab mission in May, 1996.
Did You Know That:
Both the Astro/PGBA and PHaSE experiments are housed in the Express Rack, a laboratory facility designed like those to be used on the International Space Station, rather than the normal Spacelab racks that we've flown over the past 15 years.
CDHT apparatus (above)
Deformation of a drop of
water using ultrasound.
BDND/ MSL-1 July 4, 1997.
Studying the Behavior of Fluids in Microgravity
Although not the primary emphasis of the science performed on MSL-1, fluid studies are nevertheless an important part of the overall NASA microgravity program, and are well-represented in this flight.
Capillary-Driven Heat Transfer:
"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 of this process in microgravity, in an attempt to gain insight into the unstable operation and occasional failure of the heat-dissipation devices.
The picture at left is the CHT apparatus on MSL-1.
Bubbles and Drops:
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 as a dominating force. Scientists will also explore the possible uses of ultrasound to manipulate bubbles in microgravity.
Internal Flows in a Free Drop:
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.
Did You Know That:
The Comptel experiment aboard NASA's Compton Gamma Ray Observatory has used a fluid loop to cool the electronics boxes that control the volkswagen-sized gamma-ray telescope since the launch of the observatory aboard the shuttle Atlantis in 1991.
