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Gravitational Relativistic Physics (GRP)
Low Temperature and Condensed Matter Physics
    PRESENT: Ongoing Research

Launch Date: 2005
Mission Duration: 4.5 months
Principle Investigator: Prof. Robert Duncan, University of New Mexico


DYNAMX image

Key Questions We Want to Answer:

To prove current theories about the nature of the phase transitions like the one that liquid helium passes through-when changing from a normal fluid to a superfluid-every aspect of the change must be studied. The Critical Dynamics in Microgravity Experiment (DYNAMX) examines dynamic properties of the helium superfluid transition in microgravity conditions, by studying the fluid's ability to conduct heat near the transition.

What We Already Know:

When liquid helium is cooled into the superfluid state, the helium gains new properties, including the ability to transfer heat without loss. Helium is used in these studies because it is relatively easy to obtain in a very pure form and behaves in ways that make it easy to manipulate and to study. On Earth a sample of helium is nonuniform because the weight of the liquid makes the bottom denser than the top. By testing how helium attains the superfluid state in the microgravity, it is possible to get more precise measurements of the fluid properties near the phase transition because the fluid sample is more uniform.

What We Hope to Find Out:

In the microgravity environment of orbit, the sample is uniform, so the phase transition between the normal fluid and superfluid phases occurs at the same temperature throughout the sample. This sample uniformity allows the experiment to be performed to within 10-9K of the transition. Measurements of greater accuracy are thus made possible. The data from these measurements allow for a better understanding of the physical nature of objects, and could ultimately help improve the way we live by helping transform manufacturing techniques.

How We'll Conduct Our Experiment:

To create the DYNAMX measurement cell, a special container with stainless steel sidewalls will be built. Copper foils will be placed at several heights in the cell sidewalls and will be attached to special thermometers to precisely measure the temperatures at these positions in the cell. The special high-resolution thermometers can measure temperature differences smaller than one billionth of a degree. The experiment's cell is small, about the size of a stack of quarters. The experiment consists of applying heat with a heater at a small,fixed heat-flow level and measuring the temperatures at each of the thermometer positions. The temperature differences at the thermometer positions demonstrate how well the fluid conducts heat. The temperature is then adjusted, and the measurements are repeated. By carefully scanning the temperature through the phase transition, the change in how the fluid conducts heat very near the phase transition can be deduced. In preparation for the space experiment, measurements are being made on the ground with this type of experimental cell. The DYNAMX team will use the results of ground-based heat conduction measurements to help design the experimental cell and the measurement techniques for the measurements to be conducted in orbit. More details of the experiment and its science goals can be found at the DYNAMX web site below.

Additional information:

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