Release No. 96-035
For Release: May 8, 1996
STS-77 Gas Permeable Polymer Materials (GPPM) Experiment
What Is The
The GPPM experiment uses the microgravity of space to produce
plastics that are more uniform and permeable than those produced on
Earth. The GPPM experiment is being carried out by the NASA Langley
Research Center in collaboration with Paragon Vision Sciences Inc.
of Mesa, Arizona.
What Are Permeable Plastics?
Plastics are made up of very large molecules called polymers.
Some polymers allow one or more types of gases to pass through
them. These polymers, and the plastics they create, are called gas
permeable. When used in extended wear contact lenses, gas permeable
plastics provide increased durability over soft lenses as well as
decreased health risks and easier maintenance. Permeable plastics
are ideal for the manufacture of extended wear contact lenses
because they allow more oxygen to reach the cornea, which is
essential to prevent swelling of the eye.
Why Fly GPPM Aboard The Space Shuttle?
Gravity may affect many properties of a polymer as it is formed.
The GPPM experiment, which flew aboard
STS-57 in 1993 and on
STS-63 in 1995, showed that plastics made in the
microgravity environment of the space shuttle are more uniform and
permeable than those made on Earth. Making polymers in microgravity
has also helped scientists better understand how polymers are
What Are Some Applications Of The GPPM Products?
Commercial applications of uniform, permeable plastics include
membranes for dialysis machines and monitoring blood gases,
controls for fermentation and other manufacturing processes, the
commercial production of pure gases, and highly sensitive sensors
that can monitor indoor air quality to detect dangerous gases such
as carbon monoxide.
How Does The GPPM Experiment Work?
Twenty-eight polymer materials are placed inside each of two
sealed aluminum Polymerization Modules. Each Polymerization Module
is installed in a Commercial Refrigerator/Incubator Module (CRIM),
a small refrigerator and oven in a single unit that can maintain
temperatures over a range of four to 40 degrees Celsius for
indefinite periods. Identical samples are placed in a CRIM that
will remain on Earth during the STS-77 mission. The samples made in
the microgravity environment of space will be compared to those
made in gravity on Earth.
What Will Be Done With The STS-77 GPPM Plastics?
If the GPPM experiment can produce far superior plastics once
again, Paragon Vision Sciences Inc. will apply for approval from
the U.S. Food and Drug Administration to test the contact lens
materials on humans as soon as analysis of the plastics is
complete. If FDA approval is received, Paragon could be ready to
market extended wear contact lenses made with plastics produced
commercially in space as early as the year 2000.
For more information on the GPPM experiment, contact the NASA
Langley Research Center Office of Public Affairs at (804)
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