Zero Gravity: Experiments on the Vomit Comet

Zero Gravity Space Team

We’ve all watched those space movies—Sandra Bullock floating around trying to repair a space ship, her hair twirling around her head, waving herself around the universe. It’s as fun as it looks, which I found out in 2004 on a trip on NASA’s Vomit Comet. In order to train astronauts for the feeling of zero gravity, NASA has a special plane taking off from Johnson Space Flight Center near Houston, Texas. In order to achieve zero gravity, the aircraft, a large C-130 cargo jet aircraft, follows a parabolic flight plan going up in an arc followed by descending in a similar arc. During the upward climb, gravity is about double Earth’s gravity; on the downward trajectory, gravity goes to zero.

            My opportunity to fly on the Vomit Comet was made possible by working with Jake Maule, a postdoc working with Andrew Steele. Jake, now a physician at Duke University Hospital, is a trim, sharp-looking Brit who had dreams of joining the astronaut core. His Ph.D. is in medicine, so he was looking to use that training combined with an astrobiology theme to be attractive to the very competitive NASA program for selecting astronauts. Jake and I were both interested in immunology at that time. I had purchased an instrument capable making the types of measurements that can detect complex diseases like HIV-AIDS. The instrument, an ELISA reader (enzyme-linked immuno-sorbent assay) measures the amount and strength that antibodies have in binding to the molecules, antigens, they are trying to remove from harming our bodies. To neutralize antigens, which are potentially harmful compounds, antibodies hook up with antigens in complex physical structures.

            Jake’s idea was to use the ELISA reader, to find out whether and how antibodies and antigens hook up together without the benefit of gravity. He asked to borrow my instrument. I told him, “OK, but you have to take me with you!” He thought about it briefly, and agreed. We flew down to Johnson Space Flight Center for 2 days of training. After a morning of lectures, we went into a space simulation chamber that was evacuated leaving almost no air, but all was fine because we were wearing oxygen masks. The chamber was then filled with nitrogen gas—which does not support life—and we were asked to remove our masks. It took me only 20 seconds to feel the effects—I was unable to count to five! My mask went right back on.

            Jake and I practiced our experiments in a lab on the ground. We planned to fly 40 cycles alternating between zero gravity and two-times gravity (2-G) during our 3 hour flight. Each cycle lasted 20 seconds—barely enough time to complete the manipulations needed. The morning of our flight we were given two medications to help—Dexedrine and scopolamine-one to keep you awake and the other to keep you from getting airsick. Donning NASA flight suits, 15 scientists, a flight supervisor, and the flight surgeon entered the plane. Excitedly, we set up our experiments. Ours was inside of a newborn baby’s Isolette, a plastic box with armholes for two people to attend to a premature infant, which kept our supplies from floating around the aircraft.

            We were seated for takeoff, then at 10,000 feet we moved to our workstations, where our feet were placed under straps so we wouldn’t float away. When we were about to enter zero-G, special lights flashed on. Then, as we switched to 2-G, the flight supervisor shouted, “Feet down! Comin’ up!” We heard that phrase more than 40 times.

            The first zero-G experience made your stomach do a flip-flop. Your hair raises up, your equipment floats around. Wow! Then, all too soon, you feel 2-G making you twice your body weight. A slight movement of your head and you felt nauseous, even going so far as to cause vomiting. On the second cycle, we began the manipulations. My skills on working at sea on ships tossed around by big waves trained me for this work. Opposite to me, Jake was turning a bit green. The flight surgeon floated by, offered him a barf bag, wrapped it up, and then went on to the next scientist who needed some help. I’m proud to say my stomach remained in check.

            After 40 cycles of zero G, Jake and I unplugged and floated for the next couple of parabolas. The feeling of weightlessness, even for 20 seconds, is something my body has never forgotten. The ability to float in air, even fly, is something we only dream about but never experience. The trip on the Vomit Comet let my soul soar!

            Because I was a trooper on the flight, the pilots invited me to sit in the jump seat just behind them when we were returning to Johnson. What an eye opener!  First, I saw how close we were to another airplane and how the pilots handled that. Then, a warning light came on in the panel of instruments on the plane’s dashboard. We were all connected via headsets, so I could hear them discussing the meaning of the orange light. Apparently, it had to do with the functioning of one of the two jet engines. After we safely landed, the plane was taken into a hanger for maintenance to figure out what was happening with that engine. Turns out that it needed to be completely overhauled. Our 2^nd flight was cancelled and the Vomit Comet was out of commission for months.

            Our experiments were successful. We determined that antibodies and antigens had no problems working in the absence of gravity. Although humans evolved with the benefits of a gravitational field, our biochemical systems could adapt to spaceflight.