Duke Engineers Work on NASA’s Vomit Comet

Isaac Chan (left) and Dan Choi run their experiment
and try to keep track of Duke-jersey clad Cookie Monster

In late July four Pratt seniors took turns enduring parabolic roller coaster-style rides on a NASA KC135A aircraft – nicknamed the "Vomit Comet" – to perform cellular experiments of their own design during fleeting minutes of weightlessness.

Isaac Chan, Daniel Choi, John Fang and Gary Sing, all senior year biomedical engineering majors, came away from the experience with a possible research paper to publish, vivid memories of briefly escaping gravity's bonds, new perspectives on their own futures and healthy respect for the U.S. space agency.

It all began when Choi, from Cary N.C., opened up an email from NASA linked to a video showing "college students floating around in microgravity," he recalled.

NASA's Reduced Gravity Student Flight Opportunities Program offers undergraduates chances to experience nearly 30 seconds of semi-weightlessness at a time if their proposals to use the unusual environment for research are accepted.

"I thought, 'whatever we've got to do, this is definitely going to be something cool that you won't be able to experience anywhere else,'" said Choi, who shared the video with Chan, of Raleigh, N.C., and Sing, of St. Louis, Mo.

Gary Sing (left) and John Fang

Fang, of Houston, Tex., then joined the others at Duke's Armadillo Grill to begin sketching out possible research scenarios on napkins. They then approached George Truskey, the chair of Pratt's biomedical engineering department, about possible ideas.

Truskey told them that he and William Kraus at Duke Medical Center had a grant from NASA to study changes in muscle cells. Furthermore, Kraus had hypothesized that the absence of gravity might alter the structures of the central nuclei in cells, perhaps affecting how genes behave.

"We discussed the possibility of the nuclei moving when cells were exposed to microgravity," said Fang. "So we went on from there and did some research ourselves and found this might be something to look at."

Previous studies had already revealed that muscles and bones of astronauts are altered during periods of prolonged weightlessness. The Pratt students proposed to study individual muscle and bone cells during the first 30 weightless seconds. Their logic was that a half minute was time enough for nuclei to move and deform, causing other cellular structures to alter in response.

Each experimental run could last only 30 seconds because that was the length of the Vomit Comet's periods of controlled freefall, which induced weightlessness during maneuvers over Gulf of Mexico. By the end of each of those "windows," the students would have to abruptly stop cellular motion in a way that allowed any changes to be documented.

Working with Truskey, they decided on a strategy of injecting the preservative formaldehyde to "fix" the cells in place. After fixing, the nuclei and the surrounding cellular membranes could be stained with different color dyes to track any respective movements and shape shifting.

The students also wanted to contrast cellular changes during microgravity with behavior under normal conditions as well as under elevated gravity – or "hypergravity" – that could be simulated by acceleration.

NASA's "Comet" and everything in it endured about twice normal gravity during each powered climb it made before descending into free-fall. And the students also proposed subjecting cells to up to 80 times normal G-forces by spinning them within two arms of a centrifuge.

Building an open-air centrifuge in which formaldehyde could be precisely injected into cells proved a special challenge. A graduate student in Truskey's lab helped the undergraduates develop a design allowing the chemical to flow evenly through tubes to each spinning arm after being injected through a syringe. But "the first time we did it, the needle broke off and went flying off into one of the shelves," Sing said.

NASA approved the Pratt students' proposal following a review that was "like that for a regular scientific proposal," Truskey said. "I did talk to them at a certain point, but it was largely their work. They really did it themselves, and it was very gratifying to see them do it."

After the other students joined Fang in Houston, they commuted each day to the NASA's Johnson Space Center to perform pre-flight preparations before making 15-minute trips to Ellington Field to board the aircraft.

They split up into two two-man teams that rode the Comet on different days. Since the team that flew had to receive pre-flight briefings and take powerful motion sickness medications, the two left on the ground also stayed very busy.

It was up to the ground team to keep cells alive and then load them into a student-built "experiment box" for the flight. The ground team also had to perform the hypergravity centrifuge test at the same time that the KC-135A was going through its maneuvers aloft.

Choi and Chan rode the Comet first, on July 27, and ran into problems with the experiment box. The box was designed to confine the cells inside slide flasks that were punctured by needles to inject the formaldehyde. As one needle was injecting formaldehyde, an adjacent needle had to extract air to keep the filling flask from bursting.

A major task of the in-flight team was pushing and pulling syringe plungers along the box's exterior to control these injections and evacuations. All parts of the box, plungers included, were enclosed in a plastic bag that provided the final of three levels of containment to keep formaldehyde from escaping into the aircraft's cabin.

Unfortunately on the first flight some of the formaldehyde leaked into two of the three containment barriers after a flask cracked and some sealant failed, said Chan. "Before the second flight Dan and I cleaned up the box and used a better sealant and the second flight went a lot smoother.

Sing, who rode the second flight on July 28 along with Fang, said Chan and Choi "did all the hard work the night before" by staying up to do the repairs before serving as the ground crew the next day.

Though Fang and Choi are both prone to motion sickness, NASA's anti-nausea medication got them through the stomach-dropping sensation that announces the Comet has gone into free fall. "Then you find your new frame of reference and you're just there," Sing said. "You just start floating. I can't really describe it."

BME senior John Fang
enjoys weightlessness aboard
NASA's Vomit Comet.

The foursome's Web log included plenty of words with exclamation points to describe weightlessness. "Awesome! Sweet! Totally Cool! Radical! Superb! Awe Inspiring! Amazing! Stunning! Mind Blowing! Shocking! Wonderful! Breathtaking! Thrilling! Uncanny! Marvelous! Staggering! Fantastic!," wrote Chan in his post-flight blog entry. Accompanying illustrations show the students in mid-float, a grinning Chan sharing the cabin ceiling with a bug eyed Cookie Monster clad in a Duke jersey.

More than a month after their trip to the space center, the students described how the experience has changed them.

Chan, who plans to be a physician, said the dedication he saw in NASA employees makes him "want that same enthusiasm in my work, the same professionalism and feeling of respect in everything I do."

Fang, who will also go to medical school, is "thinking I would like to get more involved in the space program and perhaps maybe investigate flight medicine," he said. "It just brought up my childhood desires to learn more about our world. I had kind of lost sight of the dreams and goals I had as a child."

Choi, who had thought about going into business after graduating from Duke, is now thinking about graduate school. "I would say the experience definitely changed me," he said. "I really want to do whatever I can to get back on the plane."

In the meantime, they are expecting to write a research paper if their continuing analysis of their formaldehyde fixed and dyed cells points to publishable results. "As an experiment it's a bit tricky because they can't go back and repeat it or vary it," said Truskey. "If the results pan out that there is an effect I'd like to see it published."

According to Truskey, between 60 percent to 70 percent of biomedical engineering undergraduates do at least one semester of independent research while at Pratt. While all four Comet riders are majoring in biomedical engineering, Choi and Sing are also double majoring in electrical engineering.