TU students try to explain Saturn's rings
Rings give Saturn a distinctive look, one that has intrigued man for
centuries. They float in bands above that world in tantalizing patterns
that always seem just out of reach.
Exploration may one day determine what comprises those rings. Long
before that day, however, a group at the University of Tulsa is trying
to develop an answer to even more fundamental queries about the rings:
How did they get there and what keeps them up?

"What makes the rings around Saturn stable?" TU physics professor
Michael Wilson said. "We know there are all these little collisions
going on in the rings and that the components of the rings are built up
and destroyed through these collisions."

Gravity is not enough to hold the rings together, Wilson said, so how
much of a role do the collisions within the rings play?

"That is what I would like to learn, something about how clusters
form," Wilson said.

There are models, schematics and postulations on what could be
happening. So far, there has been only one actual test of those
theories, and that test lasted less than 3 minutes. This summer, a group
of TU students under Wilson's supervision plans to conduct an hour's
worth of experiments using tiny, brass balls to detail how these systems
work.

Their project, known as granular agglomeration in non-gravitating
systems or Gr.A.I.N.S. for short, is scheduled for flight as part of
NASA's reduced gravity student flight opportunity program this July.
Eventually, it will journey into outer space aboard the Space Shuttle.

Their system of eight boxes, shaker, battery pack and cameras is
steadily moving from drawing board to reality. Each week the project,
funded by the Research Corp., a non-profit foundation based in Tucson,
Ariz., and TU, comes a little closer to flight.

The eight team members, including the four who will fly on the NASA
jet, share common backgrounds in physics and engineering. When they meet
each week, comments are a constant and questions fly in from every
corner. Each time the group gets together there is a sense of barely
controlled chaos and the inexorable march of time.

During one meeting, Aaron Coyner passes around a camera wrapped in foam
and encased in aluminum to record the tests. That same day, Rebecca
Ragar details construction of the cube that will hold the eight test
areas for the 0.5mm brass balls. Later, Jeremy Cain tries to use the two
dimensions of a dry-erase board to describe his three-dimensional shaker
arm and shaker motor. A few weeks later, Whitney Marshall demonstrates
how the infrared sensor that trips the camera works and Adrienne McVey
discusses ways to wrap the experiment and bolt it to the floor of the
plane.

It's kind of what you would expect from a group that refers to itself
as "Spaceballs, The Experiment," on its Web site and in casual
conversation. But there is a very serious science behind what this group
is attempting to do.

Matt Olson, the alternate for the flight and the designer of the
computer hardware for the project, takes a long look at the shaker
assembly and voices his doubts.

"If you're off, it will take forever to reset," he said. "And by
forever, we mean three to five seconds."

It's not much, but knowing that there are only 200 seconds of data in
existence, well, it means a lot. The team has 60 minutes to experiment
in the reduced gravity created by the KC-135A's parabolic loops. The
team plans 16 separate tests during that hour, leaving less than four
minutes per test.

Olson tries to put the experiment into context.

"We have to be able to show them at NASA how it works," he said.
"We
have to be able to reset it.

"Anything that happens then needs to be reversible. The experiment is
unaware that we're in Cape Canaveral or outer space."

Wilson predicted that the summer flight out of Houston would lead to a
redesign for some of the components.

"We'll have to redesign, I'm sure of it," he said. "But it will
all be
good experience for us."

In Gr.A.I.N.S., the group is trying to study the conditions "under
which a gas of balls will display behavior dominated by the formation of
a clustered state vs. that of an ideal kinetic gas," according to their
proposal to NASA. In simpler terms, they want to see if the tiny balls
used in their experiment will form clumps. What they learn on the
reduced gravity flight will go into the final design for an orbit-bound
experiment aboard a future Space Shuttle mission.

Wilson, who admits that he is most intrigued by how this work could be
applied to the rings around Saturn, said there are other Earth-bound
applications for the work.

"We're looking at how a large system of particles move," Wilson said.
"There are lots of situations where you get fluidization of particle. In
such systems, there's this tendency to form clusters."

An avalanche coming down a hillside acts like a large fluid, he said.

"How strong is the tendency to cluster," Wilson asked. "How
important
are those tendencies?"

Rather than re-create an avalanche in zero gravity, the experiment
consists of tiny brass balls moving in sapphire-walled boxes. This
summer, the finished shaker will shake, the spheres will move and
cameras will whirr. Controlled by the group's software, the project will
generate data on how the objects in each chamber relate and move.

Ian Zedalis, another member of the team, has been busy developing
computer simulations of what the 4,000 balls in identical-sized boxes
will do when shaken. How will energy transfer between them in
collisions, and at what point will they cluster should be covered by
simulations, Wilson said.

However, the group may find that predictions for what will happen by
"X" time will happen at "X" minus 3 seconds, Wilson said.

"Odds are, it will be a problem without understanding of the
simulation."

And better information to build better simulations ultimately may lead
to a better understanding of what keeps those rings orbiting Saturn.

Web site: www.granular.utulsa.edu .

Shaun Schafer, World staff writer, can be reached at 581-8320 or via
e-mail at shaun.schafer@tulsaworld.com .