What We Already Know:
Scientists describe the Microgravity Scaling Theory
Experiment (MISTE) as a "big, fundamental
experiment," because it has the potential to gather
a broad range of basic information about the
elemental behavior of all materials.
All materials, under the right conditions, become a fluid
or gas. There is a unique thermodynamic state, called the "critical
point," where the liquid and gas phases have the same density and
thus become indistinguishable. Many thermodynamic quantities go
to infinity, or zero, as this liquid-gas critical point is approached.
Advanced theoretical models-called scaling theories-have been
developed to explain these unusual phenomena. Dr Kenneth Wilson
won a Nobel Prize in Physics for discovering an elegant
mathematical method to explain these phenomena.
What We Hope to Find Out:
It is possible to study this critical point more precisely in
microgravity. Working in space avoids the stratification of the sample
that gravity causes.
The MISTE experimental cell is comprised of a coffee cup-sized
copper cylinder containing a series of thermally-conducting plates
with lots of small holes. Copper is used because it is a very good
heat conductor and helps stabilize the temperature of the fluid. The
cell is filled with liquid helium-3, which has the lowest temperature
for its liquid-gas critical point of all fluids. The low temperatures
permit using superconducting instruments so precise measurements
of pressure, temperature and density can be performed. During one of the
proposed series of experiments, the sample is heated with a specific
pulse of energy to determine its heat capacity. Extraordinarily
accurate sensors will measure these minute temperature changes.
How We'll Conduct Our Experiment:
Each time a measurement is performed, a parameter is then changed, so
that a wide range of variables can be observed in what is called the
"critical region" around the "critical point." The experiment will involve
manipulating various combinations of pressure, temperature, and density,
then measuring the fluid's properties. The results of these studies
in space will be used to test the predictions of Dr. Wilson's theory
and other theories.