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ABOUT THE INSTITUTE
News of the JFI
New center formed to study space materials
for satellites, space stations
April 12, 2001
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The University will become headquarters for a new national center
devoted to investigating the long-term performance of high-tech
materials in space with a $5 million grant from the U.S. Department
of Defense.
The center’s unclassified fundamental research program could
potentially lead to the development of new and improved materials
for satellites, space stations, high-altitude aircraft, as well
as advanced terrestrial applications.
“We’re trying to understand how all sorts of materials
are going to perform in a very aggressive chemical environment,”
said project leader Steven Sibener, Professor in Chemistry and
Director of the Materials Research Science and Engineering Center.
“Right now, in spite of the massive effort in physical chemistry
of materials that’s gone on around the world, the actual
atomic-level details by which high-performance materials react,
erode and ultimately age when subjected to the harsh chemical
environment of low-earth orbit are very poorly understood. This
is a superb opportunity to explore materials chemistry in an extreme
environment; there is a long tradition of important scientific
advances coming from studying systems under such unusual conditions.”
The grant is part of the Multidisciplinary University Research
Initiative, a program designed to address large and complex science
and engineering problems that have potential for future Department
of Defense and civilian applications. The Chicago-led center survived
a funding competition that began with 416 proposals, 48 of which
resulted in grants.
Five years of funding will begin Tuesday, May 1, for the new
effort, called the Center for Materials Chemistry in the Space
Environment.
Collaborating with Sibener are Luping Yu, Professor in Chemistry;
John Tully (Ph.D. ’64), Yale University; George Schatz, Northwestern
University; Dennis Jacobs, University of Notre Dame; Barbara Garrison,
Pennsylvania State University; and Timothy Minton, Montana State
University. Other collaborators will come from the National Aeronautics
and Space Administration, U.S. Air Force Research Laboratories
and Boeing.
The collaboration will initially focus its attention on understanding
the chemistry of polymers in space. Polymers, a class of relatively
soft, lightweight materials that includes Teflon and Kaptan, are
widely used in spacecraft design. Hard coatings such as diamond
films also will be examined. “The current materials being
used in space are still what I would call first-generation space
materials that just happen to work at some level,” said Sibener.
“We seek to go beyond such fortuitous situations and actually
develop improved new materials using molecular-level understanding
of the relevant chemistry to achieve intentionally designed performance
advantages. Recent advances in materials experimentation, chemical
synthesis and theory make this the right time to tackle this challenging
problem.”
Many people think that the orbital environment in space is benign
because outer space is perceived to be empty and quiet, Sibener
said. In fact, it is a hotbed of corrosive forces capable of eradicating
a wide variety of materials. The space environment is bathed continuously
in highly energetic and destructive ultraviolet radiation from
the sun, for example. Equally destructive, swarms of electrons,
electrically charged particles and oxygen atoms also permeate
the orbital environment, depending on the altitude, time of day
and cycle of solar activity.
Much of what is known about the effects of such phenomena on
materials resulted from the study of the Long Duration Exposure
Facility. Launched in 1984 by the space shuttle Challenger, LDEF
was mounted with a variety of metals, polymers and ceramics to
see how they would fare in the extreme space environment. The
satellite completed more than 32,000 Earth orbits at altitudes
ranging from 275 to 175 miles before the shuttle Columbia returned
it to Earth in 1990.
LDEF demonstrated how little scientists knew about the durability
of materials in space. Some samples that experts thought would
survive disappeared, while others that were expected to be destroyed
managed to endure. “It tells us that we do not yet really
have a good predictive understanding of the underlying chemistry
that determines how many of these materials will age in space,”
Sibener said.
Complicating the issue are the synergistic effects of space chemistry.
It’s one thing to understand what happens when electrons,
ions, oxygen atoms or ultraviolet radiation separately react with
a material and quite another matter to understand the reactions
when any two or three of the phenomena operate at the same time.
Orbital debris –both man-made and meteoritic–takes
its toll, too, as LDEF also showed. One question Sibener and his
colleagues hope to answer is how the microscopic defects left
by debris impacts influence the subsequent chemistry and structural
evolution of such materials.
A synthetic chemist, Yu will produce experimental polymer materials
for the collaboration similar to those used in space. Then Yu,
along with Sibener, Minton and Jacobs, will conduct laboratory
experiments on the materials with gas-surface scattering instruments
and powerful microscopes capable of monitoring material structure
at the atomic level. Theoreticians Garrison, Schatz and Tully,
meanwhile, will perform calculations to learn how various chemical
reactions would be expected to affect the new materials. The combined
experimental and theoretical insights will provide guidance to
Yu’s critical synthetic effort to ultimately design improved
compounds for space applications.
The team is eager to tackle the center’s work. “There
are not only some technological issues, but some fundamental science
that you have to address,” Yu said. “That’s why
I’m very excited about this.”
Especially appealing to Yu is the challenge presented by trying
to synthesize a polymer that resists multiple sources of corrosion
in space. In theory, a polymer coated with aluminum or some other
metal could possibly resist the corrosion.
When a marauding oxygen atom strikes the material, the atom and
the metal will react to form a surface film of aluminum oxide
that prevents further corrosion. At the same time, the aluminum
oxide would serve as a good conductor, potentially draining away
damaging floods of electrons.
Even if the new center falls short of synthesizing a new high-performance
material for space, “the fundamental science from this collaboration
will be very interesting,” Yu said.
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