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Three teams of MIT students will travel to Houston next week to carry out experiments aboard an aircraft affectionately referred to by NASA as the "weightless wonder" and by experienced MIT riders as a "vomit comet." NASA uses the modified 707 airplane, the KC-135, to study the effects of weightlessness on scientific experiments.
The MIT research projects are designed to gather data about human physiology--sound localization, peripheral vision and heart rate--under microgravity conditions where gravitational pull has been reduced to near zero. The students hope their findings will be useful to astronauts making long flights or living on the International Space Station.
The 11 MIT undergraduates and several hundred of their counterparts from other universities are participating in NASA's Reduced Gravity Flight Opportunities Program, half of them during March and the remainder in August. They will spend two weeks (March 15-27) in Houston near the Johnson Space Center where they'll get preflight training and preparation before taking a spin--actually 40 parabolic loops--on the aircraft.
"This is the first time in the history of the NASA program that three teams from one university have been selected to fly in the same cycle. In my opinion, these three experiments are excellent preparation for graduate-level research," said Air Force Col. Peter Young, a senior lecturer in aero/astro who is coordinating the MIT projects and will make the trip to Houston with the students.
Professor Dava Newman of the Department of Aeronautics and Astronautics, an experienced KC-135 rider and research advisor to the three teams, said, "Flying in the KC-135 aircraft presents a remarkable experience that you never forget. It offers the only true means of flying in a microgravity or partial-gravity environment, short of flying on the shuttle."
ROLLER COASTER RIDE
During each two- to three-hour flight over the Gulf of Mexico, the KC-135 will make repeated steep climbs and descents (parabolas), each of which creates about 25 seconds of microgravity during the drop from 35,000 to 28,000 feet. In that 25-second time span, each experimental team will gather data, then spend the all-too-brief climbing interval preparing their equipment for the next descent.
The seats of the airplane have been removed and the walls, ceiling and floors covered with padding, making a soft tube-like interior divided into five five-foot zones allotted to teams. The students will work quickly in this small space, all the while bracing themselves--one hand on ceiling and feet on floor--so they don't float around during the 25-second microgravity period.
"The best analogy is really the roller coaster," said Col. Young, who rode the KC-135 10 years ago. The increased gravity on the ascent and reduced gravity on the descent can affect "even the strongest stomachs," he said. "It's a space version of sea sickness."
"What I fear most is that some of us get sick and can't finish our experiment," said Samidh Chakrabarti, a sophomore double-majoring in computer science and brain and cognitive sciences, who will work on a project to understand how humans detect the direction of sound in microgravity.
"Whatever you do, just don't look out the window," said Col. Young. "If you do that, you see the horizon at this odd angle" and all hope of maintaining vestibular equilibrium is lost, with an effect so strong that even the ablest mind and strongest body can't cope.
Most of the group will take medication to help prevent motion sickness, "but the best thing is to have something to do," said Col. Young, "which will be no problem for these people."
The PREVIEW team (PeRiphEral Vision Experiment in Weightlessness)--senior Tyra Rivkin and junior Stephanie Chen, both of aero/astro, and biology juniors Julie Gesch and Mark Sun--designed and built an apparatus to test peripheral vision in microgravity andhypergravity. In microgravity conditions, blood flow to the brain increases, but scientists aren't sure how that affects peripheral vision. Hypergravity, which is commonly experienced by fighter pilots, causes a decrease in blood flow to the brain and a reduction in peripheral vision called "grayout" or "tunnel vision."
"To my knowledge, this is the first time this type of experiment has been done in microgravity. They've tried to simulate it on the ground," but haven't been able to recreate the physiological aspects of weightlessness, said Ms. Chen, who did an extensive literature search on the topic last summer while working as a UROP for Professor Newman. Cory Hallam (SM 1997), a project engineer in aero/astro, came up with the team's experimental concept while doing graduate work for Professor Newman.
One team member will don a special light-blocking helmet with a visor that extends about a foot beyond the forehead. Inside the tip of the visor is a tiny light that shines continuously. Mounted to the left of the wearer's head, but still inside the helmet, is a motorized, retractable car antenna equipped with another tiny light on its tip. When the aircraft enters microgravity, the wearer will push a button and the antenna will extend, slowly bringing the light into the left side of her peripheral field of vision. At the moment the light becomes visible, she'll stop the movement by pushing another button, electronically recording the light's position.
The SOLO (SOund LOcalization) team--Mr. Chakrabarti; Raffi Krikorian, a junior in computer science; and sophomores Sharmila Singh of aero/astro and Boris Zbarsky of physics and mathematics--will test our ability to determine the originating direction of sound in microgravity. This type of research could be useful in designing space habitats and developing microgravity simulations.
"When a sound wave hits your head, the shape of your head distorts it, so each ear hears the sound differently. The brain is able to take the information from your two ears and perceive things like depth and spatial location," said Mr. Chakrabarti.
This group's tools include "Fritz," a high-tech device that looks much like a wig stand, but actually has digital recording capabilities that mimic the acoustical properties of the average human head, even down to its pliable, flesh-like ears. (Fritz is on loan to the team from the German firm Georg Neumann GmbH.) Using Fritz, the team has made recordings that give the illusion of spatial depth. The test subjects will wear headsets connected to laptop computers to test their own perceptions of the sounds' originating locales.
The NIMBLE (NonInvasive Microgravity Biomedical Life Sciences Experiment) team--seniors Christopher Carr and Elizabeth Walker and sophomore David Pinson, all of aero/astro--modified a flexible, wearable computer system for astronauts that serves as a biomonitoring device and multipurpose tool. During their flights, they'll monitor the heart rate by pulse and ECG measurements during both microgravity and hypergravity periods.
In addition to the extensive proposals pulled together as part of the application process and the required follow-up report, each team is asked to develop an outreach program for sharing their experimental results with teachers, students and the public, and to ask a professional journalist to fly with them. Abigail Mieko Vargus of Technology Review and Andrew Chaikin of National Public Radio will accompany the MIT students on board the KC-135.
The NASA program is administered by the Texas Space Grant Consortium in Austin.
A version of this article appeared in the March 10, 1999 issue of MIT Tech Talk (Volume 43, Number 22).