A new museum exhibit in Washington, D.C., is honouring 11 deaf volunteers who participated in experiments in the 1950s aimed at preparing early astronauts for the stomach turning experience of spaceflight. Their hearing loss made them uniquely valuable subjects because they were immune to motion sickness.

Spaceflight is not always as glamourous as it appears. In the weightless environment, many astronauts feel nauseous when they arrive in orbit. That's because the organs of balance in their ears, the vestibular apparatus, are no longer receiving cues from gravity to detect up and down, producing uncomfortable space sickness similar to what passengers on a boat experience on rolling seas.

Galludet 11 on a vomit-comet

Deaf test volunteers preparing for a Zero-G flight (Courtesy of Gallaudet University Archives: David Meyers Collection)

One of the causes of motion sickness is a conflict between what the eyes are seeing and what the vestibular system is feeling. So if you are inside a moving ship, your body is moving with the room. Your eyes don't see the motion, but your body is feeling it. When the brain detects a conflict of information between different senses, it doesn't know which one to believe, so balance is thrown off.

It turns out that some toxins have the same effect, which is why too much alcohol makes you stagger and fall down. The body's natural response is to get rid of that poison, so it empties the stomach.

For astronauts, getting sick in space is a serious issue because if vomit is not contained, it will float around the spacecraft. That's not very pleasant for your companions, but more importantly, the vomit could get into electronic equipment and cause dangerous problems. And if the astronaut is wearing a spacesuit, the spew will remain in the helmet and could become a choking hazard and interfere with vision. That's why spacewalks are never scheduled for the first day in orbit. It takes a day or so for the brain to learn to ignore the confusing signals from the ears, until they become fully adapted to a world without up and down.

Donald Peterson in Centrifuge Tank

Volunteer Donald Peterson in a centrifuge tank. (Courtesy of Gallaudet University Archives: Jerald Jordan Collection)

Which brings us back to the our deaf volunteers. In the late 1950s, during the birth of NASA, 11 deaf volunteers were recruited from Gallaudet University in Washington D.C., a campus specializing in deaf and hard of hearing students. They became known as the "Gallaudet Eleven" and are now being honoured in a new exhibit at the university called "Deaf Difference and Space Survival" curated by student Margaret Kopp.

All but one of the volunteers lost their hearing from spinal meningitis, which can kill nerve and hair cells in the inner ear. These are essential elements of the vestibular system which helps us sense orientation and keep our balance. And it's also the system that can trigger motion sickness. For the volunteers, though, their ear damage gave them effective immunity to motion sickness. This made them perfect test subjects for devices that would be used to train astronauts. They could be spun around, tumbled end over end, fly on zero-G airplanes, even go out on a boat in stormy seas in the North Atlantic, without becoming nauseous. In fact, some experiments had to be cut short because the scientists testing them were getting too sick — while the volunteers were fine.  

Their work, which the volunteers enjoyed tremendously, provided valuable information about the effects of spaceflight on the human body. Measurements on blood pressure, eye movement, digestion and other physiological effects on the body and mind were all made possible because the volunteers could put up with gruelling environments that would make most people violently ill. If you want to understand why some people suffer motion sickness, you can learn a lot by studying those who don't.

Of course, their efforts, as well as the efforts of the female "human computers" portrayed in the movie Hidden Figures, have not appeared in traditional history books, which is why they are being honoured now.

High-flying astronauts and flight controllers in Mission Control have long been front and centre in the public eye, but now, the full picture of the many people behind the scenes who got humans into space and to the moon is finally coming to light.