A research project 10 years in the making is now orbiting
the Earth, much to the delight of its creator Rohit Trivedi, a senior
metallurgist at the U.S. Department of Energy’s Ames Laboratory. Equipment
recently delivered to the International Space Station by the Space Shuttle
Discovery will allow the Earth-bound Trivedi to conduct crystal growth
experiments he first conceived more than a decade ago.
The equipment is actually a mini laboratory, known as DECLIC
– DEvice for the study of Critical LIquids and Crystallization – will allow
Trivedi to study and even control crystal growth pattern experiments, in real
time, from his laboratory in Wilhelm Hall on the Iowa
State University
campus in Ames.
The goal is to use the microgravity environment on board the Space Station to
determine how materials form crystals as they move from liquid to solid and
what effect variations in growth conditions have on crystallization patterns.
Trivedi hopes the experiments will help explain how certain materials, under certain conditions produce particular crystal growth patterns, such as these nickel-based superconductors.
“When materials ‘freeze’ there are specific crystalline
growth patterns that appear,” Trivedi said, “and there are fundamental physics
that govern these patterns. However, small effects can have significant
influence on the patterns that form. Snow flakes, for example, form the same
basic six-sided pattern, but because of minute variations, no two are exactly
alike. These crystallization patterns play a critical role in governing the
properties of a solidified material.”
The equipment is actually a mini laboratory, known as DECLIC
– DEvice for the study of Critical LIquids and Crystallization – will allow
Trivedi to study and even control crystal growth pattern experiments, in real
time, from his laboratory in Wilhelm Hall on the Iowa
State University
campus in Ames.
The goal is to use the microgravity environment on board the Space Station to
determine how materials form crystals as they move from liquid to solid and
what effect variations in growth conditions have on crystallization patterns.
“When materials ‘freeze’ there are specific crystalline
growth patterns that appear,” Trivedi said, “and there are fundamental physics
that govern these patterns. However, small effects can have significant
influence on the patterns that form. Snow flakes, for example, form the same
basic six-sided pattern, but because of minute variations, no two are exactly
alike. These crystallization patterns play a critical role in governing the
properties of a solidified material”
While Trivedi, who is also an ISU distinguished professor of
materials science and engineering, studies primarily metals, the material to be
used in the DECLIC experiments is a transparent, wax-like substance called
succinonitrile. With a relatively low melting point, 57 degrees Celsius, the
material lends itself to study in the controlled confines of the Space Station,
and its transparency will make it possible for researchers to view the crystal
growth process as the material solidifies. However, the basic principles
governing crystal growth will be the same.
So why conduct the experiment in low gravity? Trivedi hopes
that the low gravity will “erase” the effects of convection, the natural
circulation of fluid.
“On Earth, the small effects are masked by convection,” he
said. “We hope that in a low-gravity environment, convection will be minimized
so that we can more clearly see the importance of the small effects and see how
the experimental data match our theoretical modeling.”
Much of that modeling has been done by collaboration with
Trivedi’s colleague, Alain Karma, a theoretical physicist at Northeastern University
in Boston. The
pair has also collaborated closely with the Centre National d'Etudes Spatiales
(CNES), the French government space agency that along with NASA, helped fund
the work.
After preliminary testing in September, DECLIC is scheduled
to be online in October and the first set of experiments will run through
February 2010 according to Trivedi. Through a connection with the computation
center in Toulouse, France, Trivedi’s research group
will be able to view video of the material as it solidifies. To pick up the
necessary detail, Trivedi’s lab is outfitted with a big-screen, high definition
monitor. But they won’t be just passive spectators.
“If we see something unusual, we can repeat the experiment,
all in real time,” Trivedi said. “Likewise, if we don’t see much happening, we
can alter the conditions and move on.”
All the video from the DECLIC experiments will be captured
and stored for future reference by CNES in Toulouse, France.
Trivedi’s research proposal was originally selected by NASA for funding back in
1998, receiving approximately $2 million in total through ISU’s Institute for
Physical Research and Technology, and was later selected as one of only six
projects in materials science selected for actual flight. To now be this close
to seeing the project in operation is exciting for Trivedi.
“It’s been a long time since we started,” Trivedi said, “but
it’s also given us time to finalize the experiments and work on the theoretical
side. Now we’re just anxious to get experimental results to see if things
behave as we expect.”
Trivedi’s research isn’t the only Ames Laboratory science in
outer space. Materials developed at the Lab’s Materials Preparation
Center are on board the
Planck satellite as part of the instrument cooling system.
Original article
