Before humans flew into orbit—even before an artificial satellite circled the earth—an American program put people at the threshold of space, 19 miles above the earth. They made their dangerous ventures into the unknown aboard sealed containers suspended from balloons, and experienced conditions that were virtually the same as those in outer space, with practically no air pressure and a temperature of minus 90 degrees Fahrenheit.
The program was Manhigh. It received international press coverage, with its second flight featured on the cover of the September 2, 1957, issue of Life magazine. Then, about a month after the Life article, the Soviets launched Sputnik 1, the starting gun for the space race. Manhigh was quickly overshadowed by Vanguards, Explorers and additional Sputniks even before its nearly disastrous final flight in late 1958.
Project Manhigh’s purpose was to study the physiological stresses of high-altitude flight on the human body and the effects of cosmic rays. Cosmic rays are highly charged, extremely powerful nuclear particles that move at nearly the speed of light and typically originate from millions of light years away. The earth’s upper atmosphere filters out these rays and keeps them from striking the surface. Airplanes of the future were expected to reach altitudes of up to 100,000 feet, and no one knew the dangers of sustained flight at those heights—perhaps blindness or cognitive impairment. Scientists and the military, already thinking ahead to the time when humans would venture into outer space, wanted to know the risks.
Investigations of cosmic rays on living cells by the U.S. Air Force in the early 1950s sent balloon-borne instrument packages and small animals as high as 90,000 feet for hours at a time. Aerobee and V-2 rockets launched animals to even greater altitudes. These tests provided some evidence that cosmic radiation would not necessarily be a barrier to high-altitude flying. For example, two monkeys exposed to cosmic rays for a total ofapparent learning difficulties. Mice experienced significant graying of their fur after their flights, but showed no other ill effects.
