Microgravity simulator:

ISU students experience  "Weightless Wonder"
Four Iowa State University students recently studied some weighty topics in a weightless environment, namely, in NASA's KC-135A microgravity simulator, sometimes known as the "Weightless Wonder" or the "Vomit Comet."  Their project, on acoustic liquid manipulation (ALM) in microgravity, was supported in part by the Iowa Space Grant Consortium.

The students, Trey Cauley, Joe Hynek, Sibil Joseph and Jason Schmid, tried to determine if the gas bubbles in fuel tanks can be manipulated by ALM techniques.  They worked under the direction of  J. Adin Mann, a professor in the department of aerospace engineering and engineering mechanics at ISU.

In microgravity, bubbles tend to remain stationary and can create problems in fuel tanks when they become lodged to baffles or in filters.   ALM could eliminate the need for mechanical devices like filters and screens, which are currently used in microgravity to separate bubbles from liquids in closed containers.

The students designed an experiment to test whether or not ALM could be used to loosen bubbles from baffles in a tank.  The experiment was tested in microgravity aboard the KC-135A, a plane specially fitted out for such experiments.

During the actual experiment, which took place in March in Texas, bubbles did not stick to the baffles, as the students had expected, so they were unable to test the effectiveness of the ALM techniques.  One possible explanation is that the surface tension of the bubbles in microgravity was too strong for the bubbles to adhere to the baffles.  However, there is a good chance that an improved version of the experiment will be performed in the spring of 2002.

For more detailed information, visit the project's website.

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The Experiment

The students built a small tank with movable baffles.  Transducers mounted on the outside of the tank were aimed at the baffles.  The tank was attached to four springs, which allowed the tank to be shaken so that bubbles would form.  Once bubbles became attached to the baffle walls, the transducers were turned on to determine if the bubbles could be knocked off.   The transducer creates ultrasonic waves; energy from the waves pushes the liquid, which in turn pushes whatever the liquid contains, such as bubbles.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

The KC-135A

The KC-135A takes a parabolic flight path to achieve Zero-G.  When the plane begins to reach the top of the parabola, it starts to fall back down.  The Zero-G period lasts about 25 seconds, during which time the plane goes from 36,000 ft to 14,000 ft.

In case the plane became depressurized, the students were trained by NASA to recognize the signs of hypoxia, a condition that occurs when a person is subjected to oxygen deprivation.  In such a situation, the students would have needed to quickly don an oxygen mask before they blacked out.