Fact sheet
number: FS-2004-01-02-MSFC
Release date: 01/04
Miscible
Fluids in Microgravity (MFMG) Investigation
Experiment
Name: Miscible Fluids in Microgravity (MFMG)
Mission:
Uses onboard apparatus and materials to conduct an experiment during
International Space Station Expedition 8 and/or Expedition 9
Experiment
Location: Destiny Laboratory Module
Principal
Investigators: Dr. John Pojman, University of Southern Mississippi,
Hattiesburg, Miss., Co PI: Vitaly Volpert, Université Lyon I, Hermann
Wilke, Institute of Crystal Growth, Berlin, Germany
Project
Scientist: Mark Paley, NASA Marshall Space Flight Center, Huntsville,
Ala.
NASA Managers:
Melanie Bodiford and Ron Young, NASA Marshall Space Flight Center
Overview
On Earth
and in space, fluids are essential for most living things and for making
materials and operating machines. But fluids do not behave the same on
Earth and in the low-gravity, or microgravity, environment inside the
orbiting International Space Station.
In space,
processes usually masked by Earth's gravity become much more evident --
playing a bigger role in the process of mixing fluids to make materials.
This experiment
studies how miscible fluids -- those that completely dissolve -- interact
without the interference of gravity.
Studying
the interactions between molecules that make up liquids is important for
improving numerous processes ranging from making plastics to manufacturing
medicines.
Experiment
Operations
Immiscible
fluids, like oil and water, exhibit "interfacial tension" or surface tension.
Oil and water are made of different types of molecules that pull on each
other -- preventing the two substances from remaining mixed together --
even after stirring.
On the other
hand, when miscible fluids -- like the honey and water -- are mixed on
Earth, they dissolve and combine easily because they are made of similar
types of molecules.
This experiment
will test a 100-year-old-theory impossible to confirm on Earth. In the
mid-1800s, Dutch scientist Diedrick Korteweg predicted that until the
molecules of miscible fluids like honey and water diffuse together and
become a uniform solution, these fluids would act like immiscible fluids.
In microgravity,
if a stream of one immiscible fluid is injected into another, the stream
will break into drops. This happens because of a surface-tension-driven-phenomenon
called Rayleigh-Tomotika instability. This test will determine if the
same breakup occurs with two miscible fluids by injecting honey into water
and observing if the honey stream breaks into drops.
Gravity
prevents this experiment on Earth. Because the honey is denser than water,
the honey sinks in the water. Also in microgravity, a drop of immiscible
fluid injected into another fluid will always become spherical. For this
experiment, the crew will inject a drop of water into honey to see if
it behaves the same way.
Another interesting
phenomenon that a drop of an immiscible fluid can exhibit is droplet migration.
An immiscible drop can move in weightlessness when it is placed in another
fluid that has a variation in a temperature - a temperature gradient.
Using honey and water, the crew member will test if a drop of water in
honey and a stream of honey in water will migrate in a temperature gradient.
To conduct
this experiment, astronauts will use equipment already on board the Space
Station: honey used to sweeten tea and syringes used for life sciences
experiments.
For the first
experiment, astronauts will use a syringe to inject dyed honey into water.
Within 2 seconds, they will create a stream of honey 2 centimeters long.
Under normal gravity, the stream would sink. In weightlessness, the stream
can be formed but it is not known if the stream will break up like a stream
of oil in water would do - an effect known as the Rayleigh-Tomotiak instability.
In the second
part of the experiment, astronauts will inject an aspherical drop of dyed
water, approximately 0.5 milliliters (0.02 fluid ounces) into the honey
for 5 seconds. The process will be videotaped for 30 seconds to determine
if the aspherical drop of water will spontaneously assume a spherical
shape-which is what a drop of water would do in oil.
To test for
thermal migration of miscible fluids, the syringe will be attached to
the Commercial Generic Bioprocessing Apparatus (CGBA), maintained at body
temperature, 37 °C. This will create a temperature variation across the
fluid in the syringe. When the drop of water or the stream of honey is
injected, video will reveal its migration and show the direction of its
movement.
Investigators
on the ground will be able to watch video of the experiments as they are
conducted in space. The results will be compared to computer simulations
performed by Vitaly Volpert and Nick Bessonov at the Université Lyon I
in France.
Benefits
Demonstrating
the existence of an effective interfacial tension in miscible fluids will
open up a new area of study in materials science. These fluid flow processes
may affect the way many polymers are made. This research could help scientists
improve the way plastics and other polymers are produced on Earth and
in space.
More Information
More information
on this experiment and other Expedition Eight experiments is available
at:
http://www.spaceresearch.nasa.gov/
http://www.scipoc.msfc.nasa.gov/
http://www.spaceflight.nasa.gov/
http://www.microgravity.nasa.gov/
http://www.pojman.com/
