The Limits of the Human Body in Space: An Illustrated Guide

By Alexis C. Madrigal

As soon as we saw outer space as a frontier to be visited, all of the things our bodies took for granted had to be considered problems


Perhaps nothing has reminded humans more of our fundamental organismness than traveling to outer space. All of the things our bodies take for granted on Earth -- gravity, atmosphere, oxygen, a relatively narrow range of temperatures -- suddenly had to be considered as problems to be solved. NASA scientists and their corporate counterparts at places like Douglas Aircraft attacked the problem like engineers, not biologists.


To them, the body was, or at least could be viewed as, a machine. And that meant its materials and processes could be subjected to QA. What kind of exposure could humans take to heat and radiation? What level of vibration caused debilitating testicular pain? What kind of acceleration knocked them out? How long could they operate under stress? What did weightlessness do to them? They drew curves, extrapolating out to death and incapacitation, and then began to work on the solutions that would keep people out of the danger zone.

In later years, everything seems very official and thought-out, but in the couple of years after Yuri Gagarin's milestone flight into outer space, very little was actually known about how humans would respond to the extraterrestrial environment or what kinds of spaceships they might need to stay alive.

In this post, we look back at Albert Schwichtenberg's 1962 address to medical colleagues, which was transcribed in a paper "Space Medicine and Astronaut Selection." In it, he discusses some of the knowledge that people had acquired about human limits. Those facts were acquired at the Lovelace Clinic in Albuquerque, New Mexico, where bright-eyed volunteers gave their bodies up for experimentation in the name of space science beginning at the end of the 1950s and continuing into the most glorious decade of human spaceflight. Stephanie Nolen recounted this time period in her book, Promised the Moon:

In 1959, no one had ever traveled beyond the pull of gravity, and nobody knew what being in space would do to the human body: would the heart cease to beat and the control of the other muscles fall away? Would eyeballs lose their shape, perhaps drift out of sockets? Would food stick in the throat, refusing to be swallowed? The doctors at Lovelace had no idea, and so they did every test they could think of. They tried to shake the men's bones with blasts of sound, sat them under pulsing strobe lights, induced vertigo, plunged them from light to dark and counted how long it took to focus their eyes again.

All those tests, and others performed around the country, generated the charts you'll see below. But the way of thinking about the human body in this way came from other fields -- astronautics, electronics, cybernetics and classic engineering. Manfred Clynes coined the word "cyborg" the year before Gagarin's flight, a portmanteau of cybernetics and organism. The concept arose specifically from the challenges of putting Homo sapiens in space.

"Space travel challenges mankind not only technologically but spiritually, in that it invites man to take an active part in his own biological evolution," Clynes and coauthor Nathan Kline wrote in their cyborg paper in Astronautics. "Scientific advances of the future may thus be utilized to permit man's existence in environments which differ radically from those provided by nature as we know it."

The body, if it was just a machine, could be reengineered. So, the charts below form simply the starting point for a new kind of human organism. These were nature's limits, but the act of reaching space had shown that people did not have to be bound by the earthly or natural.

And now, we present you with the illustrated guide, drawn from Schwichtenberg's paper, on the limits of the human body and how they might be overcome.












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