Berkeley - For a brief time last February,
Diana Chai was her own guinea pig. Strapped to a treadmill
in a NASA research plane, she calmly jogged in place as the
KC-135 executed a series of zero-G dives 50,000 feet over
"It was amazing, the best experience ever," said Chai,
a junior majoring in bioengineering at the University of
California, Berkeley. "And I didn't even throw up."
Chai, 20, and three other UC Berkeley students participated
in a special NASA program that gives college students access
to one of its unique assets, a research plane - often referred
to as the "vomit comet" - that simulates the weightlessness
This Saturday (May 5), the four-person team will demonstrate
an experiment they conducted on the NASA plane at the Lawrence
Hall of Science from noon to 2 p.m.
The NASA Reduced Gravity Student Flight Opportunities Program
has been in existence since 1995 out of NASA 's Johnson
Spaceflight Center in Houston, administered by the Texas
Space Grant Consortium. Chai and her co-scientists, the
first UC Berkeley students to apply for the program, proposed
to test an improvement to the treadmills astronauts pound
regularly in space to prevent bone loss and potential injury.
Without such high-impact exercise, astronauts can lose as
much as 2-3 percent of their bone mass per week.
With the help of NASA scientists and a borrowed 500-pound
treadmill, the team spent two weeks, Feb. 8-17, at Ellington
Field near Houston setting up their experiment for two flights
of the same Boeing KC-135A used to train astronauts. On
Feb. 13, during their first series of 30 zero-G dives, each
30 seconds long, Chai and recent UC Berkeley integrative
biology graduate Lanny Rudner, 22, were the guinea pigs,
running at 6.5 miles per hour while strapped into the treadmill.
A day later, Chris Hamerski and Bev Guo, both 22, flew another
series of tests.
Just for fun, each group reserved a few parabolic dives
for floating and tumbling around the plane, an experience
Chai compared to the Drop Zone ride at Great America.
"I'm still on a high from the trip," she said.
As for the experiment, preliminary results indicate it
was a success.
"This was a very challenging project to pull off, but they
did it, thanks to an enormous amount of help from NASA people,"
said Rodger Kram, a former UC Berkeley assistant professor
of integrative biology who first suggested the idea to the
team and served as their faculty advisor. "This project
not only may benefit NASA and astronauts, but it also gave
the students a great experience. They were totally charged
Chai and Rudner first got excited about zero-G experiments
while taking a course called "Mars by 2012," taught each
year at UC Berkeley by former NASA engineer Larry Kuznetz.
After presenting a class paper about simulating reduced
gravity on Earth, they cast about for ways to further their
interest until Kram suggested they propose an experiment
for the NASA program.
The two teamed up with Guo, now a senior majoring in integrative
biology, and Hamerski, who graduated last year in molecular
and cell biology, to write and submit a proposal. It was
accepted last summer, but postponed because of airplane
maintenance until this spring, when the foursome flew with
47 other teams from around the country.
The idea behind treadmills in space is to mimic the pounding
and leg stresses astronauts would experience while walking
or running on Earth, in hopes of preventing the bone deterioration
seen on long space flights.
The problem, said Kram, now in the Department of Kinesiology
and Applied Physiology at the University of Colorado, Boulder,
is that treadmills in use today are not very effective,
primarily because they rely upon awkward and uncomfortable
rubber bands to pull astronauts down onto the treadmill
as they run. The elastic straps hurt so much that astronauts
run in a crouched position with bent knees. While this is
less painful, "they're not banging their bones the way they
need to," Kram said.
Based on laboratory experiments with simulated reduced
gravity, Kram and his UC Berkeley colleagues recently showed
that runners could increase peak impact forces while using
only a moderate downward pull from the shoulder straps if,
at the same time, another rubber band pulled them forward.
"The idea is, if you could combine a moderate downward
pulling force with this forward pulling force, they'd get
the same kind of impacts that you'd need to stimulate the
bones," he said. It's like running downhill, added Chai.
Hamerski, who will enter medical school this fall at UC
San Francisco, had performed essentially the same experiment
in simulated reduced gravity for his senior thesis in Kram's
Earth-bound Locomotion Laboratory.
"In the Locomotion Lab, we used a modified mountain climbing
harness to pull upward with rubber bands to simulate reduced
weight," Hamerski said. "The KC-135 gave us the chance to
try this in zero-G."
In an article in the May 2001 issue of the Journal of Biomechanics,
UC Berkeley graduate student Young-Hui Chang, Hamerski and
Kram provide convincing evidence that this forward-pulling
harness works. While pulling down with only 38 percent of
a runner's weight - the force of gravity on Mars - and pulling
forward with about 1/5 the runners' weight, they found they
could increase the impact force to more than a runner would
experience under normal gravity.
"We've shown that you can increase the functional loading
a runner experiences and mimic what they experience on Earth,"
said Chang, now a post-doctoral fellow at Emory University
in Atlanta, who got the idea of pulling forward while studying
the metabolic costs of alternately braking and speeding
up when running. "Now it's up to NASA to give it a try and
see if impact forces comparable to those on Earth actually
prevent bone loss."
The airborne experiment by Chai, Rudner, Hamerski and Guo
was the first microgravity test of this hypothesis, and
it confirmed what Chang and Kram had predicted.
"We got to one-G impacts with only a half-G downward force
and 20 percent reduced G horizontal force," Chai said. "That's
in the comfort zone, and a lot easier than running when
you're pulled down by a force of one G."
Staff members with the NASA program seemed intrigued by
the students' experiment, and Kram thinks that NASA scientists
would be interested in looking more closely at the technique.
"This project is going somewhere. It's not very fancy,
but it seems to be one of the more promising solutions to
bone loss during long-term space flight," he said.
As for the students, they're captivated by space. Rudner
has been accepted at Baylor College of Medicine, where he
hopes to become a flight surgeon, and Hamerski said he would
find it "awesome" to some day practice medicine in space.
"These students are the dreamers who want to be astronauts,"
Chai, who plans to pursue an MD/PhD, is hooked too. "I
want to find another project and fly again," she said.
Funding for this project was provided by the California
Space Grant program, the University of California's California
Space Institute (CalSpace), the new Center for Excellence
at UC Berkeley's Space Sciences Laboratory, the University
of California Chancellor's Fund and the Texas Space Grant