Thank You for Flying the Vomit Comet

Contents

• BODY OF ARTICLE
• T-Minus Eight Months
• T-Minus One Week
• Flight Week
• Our Flight
• Acknowledgments
• REFERENCES
• About the Author
• FIGURES

This paper describes our flight aboard NASA's C9 “Weightless Wonder,” an aircraft that creates multiple periods of microgravity by conducting a series of parabolic maneuvers over the Gulf of Mexico. Because passengers often develop motion sickness during these parabolic maneuvers, the C9 is more affectionately known as the “Vomit Comet.” To celebrate the 2005 World Year of Physics, AAPT, APS, and NASA co-sponsored a contest in which teams of high school students and their mentors could fly an experiment aboard the Vomit Comet. If selected, students would develop their experiment and travel to Houston to serve as “ground crew” while the mentors would actually fly aboard the C9 to perform the experiment.

Our proposal explored how thin strands of liquid, suspended between two moveable supports, would handle the stresses of entering and exiting microgravity. To record the stability of these “liquid bridges,” we would construct an apparatus that films the bridges while a three-axis accelerometer records the motion of the C9. In January 2005, AAPT announced that our experiment was one of six proposals that had been selected to fly. Our experimental results have been posted online.¹ Also, NASA's website, http://zerog.jsc.nasa.gov, has hundreds of photographs of our experience (under the “Student Campaign” link).

Our flight was scheduled for late September 2005 and was coordinated by NASA's Reduced Gravity Program (RGP) out of Ellington Airfield, located a few miles northwest of the Johnson Space Center. We were assigned a NASA mentor to help us meet the RGP's experimental hardware constraints as well as navigate us past the mountain of paperwork required for flight aboard the C9. Each flyer was then required to be certified “flight-ready” by submitting to an FAA flight physical, the same head-to-toe exam pilots undergo that places heavy emphasis on visual acuity.

Through the summer of 2005, we constructed our experimental apparatus. Our device was simple in concept but grew in complexity as we attempted to meet NASA's requirements for flight-worthy hardware. Every piece of equipment that flies aboard the C9 must be described in a “Test Equipment Data Package” (TEDP), a comprehensive report of the hardware's safety qualifications and ability to withstand a catastrophic 9-g crash of the C9 without injuring the flight crew or passengers. Specification sheets for every nut and bolt of hardware must be submitted. Even for a simple off-the-shelf mounting bracket, we had to supply NASA with the bracket's dimensions, tolerances, operating temperature, impact strength, etc. The entire apparatus must then be described in terms of its electrical power consumption, flammability, laser usage, operational pressure range, etc. Our TEDP was resubmitted a dozen times before the actual flight.

As our flight week of Sept. 21–30 arrived, so too did Hurricane Rita. Our flight was scheduled for the exact day that Rita slammed into Houston and forced the first and only shut down of Mission Control while Americans were in space. Like many NASA flights, ours was postponed several more times. We were eventually rescheduled for May 2006.

The additional eight months of time allowed us to improve our hardware and rehearse the procedures needed to perform the in-flight experiment. Most notably, we automated most of our experimental procedures. Because head movement is the leading cause of motion sickness while flying aboard the C9, automating our apparatus helped keep our team members from becoming victims of the Vomit Comet. When our rescheduled flight week of May 3–12 finally arrived, we shipped our improved apparatus to Ellington and headed for the now calm waters of the Gulf of Mexico.

Our first two days at Ellington were spent in physiological training courses culminating in a ground-based altitude chamber test that simulated atmospheric conditions at 25,000 ft. The purpose of this simulation was to see how each flyer would react to hypoxia if the C9 experienced a rapid decompression during flight. After hours of coursework, we started the chamber test by donning fighter pilot's masks and “denitrogenizing” our bodies by breathing pressurized oxygen for 30 minutes. Once we were denitrogenized, the chamber simulated an ascent to 25,000 ft at a rate of 5,000 ft/min. During this ascent, the gas in everyone's intestinal tract expanded to three times its normal volume. At some time, everyone in the chamber had to release this gas, which we were encouraged to do as often as possible. Luckily we were wearing oxygen masks for most of the simulation. Unfortunately we were not wearing earplugs. Once at 25,000 ft, half of us were asked to remove our oxygen masks for five minutes while the other half noted our response to hypoxia. When I removed my mask, I felt no symptoms of hypoxia for the first three minutes. At three minutes, my head began to throb and I couldn't perform basic tasks. NASA personnel inside the chamber (who thankfully keep their masks on) distributed a 5th-grade-level quiz to test our brain function. I was able to spell my last name but could only remember three of the past five presidents. Some people in the chamber became giddy and just laughed uncontrollably for the remaining two minutes. One gentleman simply sat with a blank gaze. He never responded to various instructions and eventually had to be helped back into his mask. At four minutes, my peripheral vision was totally gone. By five minutes, I was unable to write and was beginning to black out. Once everyone was back on oxygen, the chamber simulated a descent to ground at a rate of 2,000 ft/min. Following the chamber flight, NASA had a little surprise waiting for us—we were secretly filmed during the chamber test. We all gathered to watch the reaction of various participants and were shocked to learn that everyone thought they acted normally until they saw themselves on film.

We spent the next day preparing for and undergoing our team's “Test Readiness Review” (TRR). During the TRR, a group of roughly 10 stern-faced NASA personnel (scientists, pilots, and flight surgeons) inspected every piece of experimental hardware flying aboard the C9. To get an idea of what a TRR is, imagine a giant science fair occurring in a 120°F airplane hangar underneath the wings of the C9. Each apparatus was set up on a table and surrounded by the high school students and mentors. The NASA personnel moved from table to table demanding that each apparatus be modified in some way to guarantee flight safety, then revisited a few tables to see how the modifications were progressing. Figure 1 shows a nervous moment during our TRR, while Fig. 2 shows the joyous moment when our apparatus was “officially certified for flight” and loaded aboard the C9.

Figure 1.

Figure 2.

After 18 months of preparation, the day of our flight finally arrived. The C9 was scheduled to take off at 10:00 a.m. At 9:00 a.m., a flight surgeon administered a “cocktail” of Scop-Dex to each member of our flight crew. Scop-Dex is a combination of Scopolamine and Dexedrine tablets, given to help with motion sickness. Historically, 60% of first-time flyers aboard the C9 experience significant motion sickness, including nausea and vomiting; however, when using the recommended dosage of Scop-Dex, this motion sickness rate drops to 15% or less. Finally, each member donned an olive-colored flight suit, complete with a highly coveted personalized name patch and multiple plastic “barf-bags” on the chest and legs. To avoid any messy surprises during microgravity, a thorough tutorial on proper vomiting techniques was given, and twice reviewed, in the half-hour before flight.

After takeoff, the C9 quickly reached 25,000 ft and the crew gave us the OK to leave our seats and prepare our experiment, which had been locked-down for takeoff. The interior of the C9 is the size of a typical DC-9 aircraft—I'm 58 and could easily reach the ceiling of the C9 with both arms outstretched. The striking feature of the interior is that with the exception of a few seats at the rear of the aircraft, where we sat for takeoff and landing, the entire aircraft is void of seats. Instead, the interior is covered by a shiny white two-inch-thick foam padding, brilliantly illuminated by two banks of overhead lights that run the entire length of the aircraft. Every 10 ft, an experimental apparatus is bolted to the floor. As shown in Fig. 3, VELCRO® belts are also located in front of each apparatus so that experimenters can secure themselves during moments of microgravity.

Figure 3.

The C9 then climbed from 25,000 ft to 35,000 ft at a 4 ° ascent angle. This ascent only took ~25 seconds, during which time we experienced a 2-g force towards the floor. The C9's trajectory is designed such that all g-forces are normal to the floor with almost no variations occurring in other directions. I remember the eerie sensation of my flight suit being pulled to the floor and feeling like it was a very heavy liquid being poured over my body. When the C9 reached the top of each parabola (see Fig. 4), a crew member screamed out, “Over the Top!” As the C9 angled 45° down and returned to the 25,000-ft altitude, we experienced the ~25-second interval of microgravity. At the bottom of each parabola, as the C9 pulled out of its nosedive and into another 45° ascent, the crew member then screamed, “Feet Down,” which was our warning that the 2-g forces would soon hit us. We had perhaps two seconds to orient our feet to the floor before the oppressing 2-g's kicked back on. This cycle repeated 42 times: the flight plan called for 10 parabolas out of Houston to Mexico; a five-minute turn; 10 parabolas back to Houston; another five-minute turn; 10 parabolas back to Mexico; a final turn; then 10 parabolas back to Houston. After these 40 parabolas, we were treated to a single parabola simulating lunar gravity, then a final parabola simulating Martian gravity. Each flight lasted two hours from takeoff to landing, with the 42 parabolas lasting only about an hour. Each team was given two days of flight for a total of 84 parabolas.

Figure 4.

During the ascent portion of each parabola, I mostly recall hearing the C9's engines straining to climb. As the C9 went “over the top” and through its descent, the sounds of the straining engines were replaced with the stark silence of idle engines. Strangely, one can anticipate the periods of microgravity by listening to the plane. The silence was then quickly interrupted by the happy (usually) outbursts of the flyers. During periods of microgravity, I was completely free to bounce around the interior of the C9—the slightest touch of a wall sent me spinning and bouncing against the padded surfaces, perhaps the best demonstration of Newton's laws of motion one can imagine. If you've ever ridden a roller coaster, you've experienced that brief exhilarating instant as the coaster goes over the top of the first hill and you feel that split instant of microgravity. If you're like me, your body just instinctively craves for gravity to kick in, at the bottom of the hill. Aboard the C9, that feeling of going “over the top” lasts for ~25 seconds. You need a few parabolas to get accustomed to the prolonged feeling of exhilaration and to realizing that gravity isn't immediately returning.

NASA hopes that each flight of the C9 is a “No Kill” flight, meaning that no one onboard vomits. Though no one on our team vomited, neither of our two flights were “No Kill.” On each flight, two to three flyers became sick enough that they vomited and had to leave the experimental area and return to their seats at the back of the plane. Each flight had at least one flyer who vomited during all 42 parabolas. NASA emphasized that conflicting sensory signals to the brain are the most common cause of nausea and that no factors predict who will get sick during flight. We were encouraged not to move our heads too rapidly, not to look out the window at the horizon (feeling weightless while seeing a vertical horizon certainly will send confusing sensory feedback to the brain), and not to try any overly ambitious gymnastic feats. For whatever reason, everyone on our team seemed to do very well in microgravity and we were all able to enjoy a few parabolas of somersaults, handstands, and Superman-stunts as shown in Fig. 5. One memorable moment was taking several self-portraits by activating the timer on my digital camera and aiming it at me while the camera floated in microgravity. NASA graciously provided onboard photographers and videographers to preserve our experience on DVD.

Figure 5.

The authors wish to acknowledge our student “ground crew,” chaperones, and various personnel for their hard work and expertise over the past 18 months: Carrie Blakeley, Doug Blakeley, Dick Bradley, Adam Cain, Carmela DiLisi, Emily Infeld, Laura Manson, Leslie Okeson, Tom Phillips, Larry Stevanus, and Jay Tarby. We also acknowledge the scores of individuals from AAPT, APS, and NASA's RGP who made this experience possible—we cannot mention everyone by name, but the entire staff couldn't have been more generous or more professional to our team.

Auxiliary Material (EPAPS)

Reference

1. See the file Reduced Gravity Program Results.pdf at E-PAPS-PHTEAH-45-005702. For more information on EPAPS, see http://www.aip.org/pubservs/epaps.html. [EPAPS] first citation in article
   

1. Orbital Motion of Electrically Charged Spheres in Microgravity
   Shubho Banerjee et al., Phys. Teach. 46, 460 (2008)

Robert Dempsey received his B.S. from the University of Michigan in astronomy and physics and his Ph.D. from the University of Toledo. He is currently a Johnson Space Center flight controller for the International Space Station, where he has received numerous NASA awards including citations for his service during on-orbit crises and recovery.NASA/Johnson Space Center - DF25, Houston, TX 77058

Gregory A. DiLisi received his B.S. from Cornell University in applied and engineering physics and his Ph.D. from Case Western Reserve University in experimental physics. He is currently an assistant professor of science education at John Carroll University, where he teaches physics, science methods, and instructional technology courses.20700 North Park Blvd., University Heights, OH 44118; gdilisi@jcu.edu

Lori A. DiLisi received her B.S. in aerospace engineering and M.S. in fluid and thermal sciences from Case Western Reserve University. Her graduate work focused on the spread of flames across pools of alcohol. She works for the Parker Hannifin Corporation's Nichols Airborne Division, where she designs fuel pumps for aircrafts and missiles.711 Taylor St., Elyria, OH 44035

Gretchen Santo received her B.S. from the University of Dayton and is currently the science department chair at Beaumont High School for Girls. For the last twenty years, she has been teaching life science courses and currently teaches senior-level biology courses and laboratories.3301 North Park Blvd., Cleveland Heights, OH 44118

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Fig. 1. During our “Test Readiness Review,” the Vomit Comet's flight crew, ground crew, and flight surgeons inspected every piece of experimental hardware for flight worthiness. First citation in article

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Fig. 2. After passing the TRR, our student team loaded our experiment aboard the Vomit Comet. First citation in article

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Fig. 3. During our flight, we used VELCRO® belts to hold us in place while conducting our experiment. Researchers wore olive-colored flight suits while NASA personnel and videographers wore blue flight suits. For safety, each team of flyers was closely monitored by several NASA personnel who made sure our feet were oriented to the floor of the C9 whenever the plane reached the bottom of its arc. (Photo courtesy of NASA) First citation in article

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Fig. 4. One parabolic arc in the flight of the Vomit Comet. After reaching an altitude of 25,000 ft, the C9 climbs to 35,000 ft, at a 45° angle, creating the ~25-s period of 2 g. After going “over the top,” the C9 drops back to an altitude of 25,000 ft, creating the ~25-s period of microgravity. This maneuver is repeated 42 times. (Photo courtesy of NASA) First citation in article

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Fig. 5. NASA encouraged each team to focus on their experiment, but to also allot some time to enjoy microgravity. NASA asked each flyer to plan “a fun moment” for his/her flight—a simple but fun thing that each flyer could do to remember the flight. I floated my digital camera in microgravity and activated its timer to take my picture. (Photo courtesy of NASA) First citation in article

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Fig. 6. Our student team: (backrow l-to-R) Anna Faist, Grace Kozan, Bridget McMurray, Gretchen Santo, Suzanne Maloney, Jennifer Haag, and Anna Mohr. (kneeling L-to-R) Mary Ryan and Rachel Hubbard. First citation in article

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