Oman claims that Skylab forced the issue. “Five out of nine got sick,” he says. “So NASA said, ‘Whoa, this is not some strange disease of Russian cosmonauts.’ ” Crew members on board Salyut, the Soviet space station, had been dealing with similar problems, he says. “Then space motion sickness came out of the closet in the first 50 shuttle missions.”
On Garriott’s next spaceflight, aboard space shuttle STS-9, which carried the large-volume Spacelab-1 in its cargo bay, he was first in after the vehicle reached orbit. He met the same fate as Lousma a decade earlier. “The adjustment was similar, except that I threw up, which I didn’t do on Skylab,” he says.
The simplest explanation for space sickness mirrors that of car sickness. It’s a sensory conflict in which the semicircular canals and otolith organs of the inner ear, which make up the vestibular system, tell you one thing—for example, that you’re moving—while your eyes, fixed on a book in the car or an instrument panel in the shuttle, tell you that you’re standing still.
A fundamental difference is that in a moving car, or even in the high performance T-38 supersonic jet that astronauts use to train, you’re still subject to Earth’s one-G pull. In orbit, you’re in continuous freefall, which just can’t be duplicated on Earth. People who can tolerate motion sickness on Earth sometimes suffer the most from space sickness. And the common pale face that precedes a bout of retching on Earth doesn’t happen in space because of the fluid shift upward.
There are few good predictors of who will suffer space sickness. But statistics show that between 70 percent and 90 percent feel it in some form on the shuttle, and about one in ten suffer severe symptoms including retching. Senator Jake Garn became the poster child of the puking shuttle flier on STS-51D in April, 1985, and astronauts now jokingly use the “Garn Scale” to rate their own severity.
Oman claims that vision plays a complex role in space sickness. “What seems to be happening in weightlessness is that when you put your feet toward the ceiling, something fundamentally changes. Your brain says, ‘Wait, that’s supposed to be the floor down there.’” Like the famous Necker Cube perception riddle, the orbiting brain goes through a series of visual illusions during its first days in orbit.
Medical doctor and two-time shuttle flier Bill Thornton, who got sick to his stomach on his first flight, STS-8, takes a scientific view of the process, calling it a “beautifully self-limiting adaptation” to an unusual environment. “Neuro-vestibular adaptation is an ancient evolutionary adaptation that conferred Darwinian survival advantages to our ancestors,” he assures, “especially to our arboreal ancestors. It’s a two-part process. The obvious component, miscalled sickness, protects the organism by more or less immobilization; while the second component, an individual adaptation, takes a day or so to reprogram components of the nervous system to allow for safe and effective activity in weightlessness.”
He admits that it tends to sneak up on you. “The first inclination you have is that you vomit your tonsils up in a couple heaves. I went on and on for about 36 hours. Then it was over, and I could do snap rolls and all the other tricks. So I had an invaluable firsthand experience.”
For some professional astronauts, the answer lies in taking antihistamines like promethizine (Phenergan), and scopalamine. But opinions are mixed about their risks. They cause drowsiness that some astronauts would rather avoid, even if it means gritting one’s teeth through a few days of space sickness. Many astronauts try to keep their heads as still as possible for the first 48 hours of a spaceflight, and definitely avoid the mirthful tumbling seen in countless film clips from orbit. Many shuttle commanders encourage their crews to remain upright with respect to each other and to any wall displays for the first few days of a flight.
Space tourism promoters may some day give similar advice to passengers bound for orbiting hotels. And if the bag has to be used, make it a good seal.