Of all the strange experiences that may await the astronaut, none will be quite so strange, the experts agree, as weightlessness. This phenomenon will occur as soon as the spaceship reaches a speed at which the rocket’s centrifugal force cancels the pull of the earth’s gravity, and when it does, the space man, whether settling into orbit or making for Venus or Mars, will know for certain that he has arrived in outer space. He will weigh nothing. The air in his cabin will weigh nothing. The warm carbon dioxide he breaths out, being no lighter than the air in the cabin, will not rise, so he will have to exhale forcibly. Momentum, the force whirling the ship on its course, will rule its interior as well, and with possibly weird results. All objects that are not in some way fastened down—a map, a flashlight, a pencil—will float freely, subjecting the space man to a haphazard crossfire. If he were to drink water from an ordinary tumbler, the water might dash into his nostrils, float there, and drown him. Ordinary tumblers will not be used, however; plastic squeeze bottles will. (“The proper-size orifice is being worked out,” I was told by Major Henry G. Wise, of the Human Factors Division, Air Force Directorate of Research and Development.) Far more startling than the movement of objects, though, will be the space man’s own movements. Normally, in making a movement of any kind, a man has to overcome the body’s inertia plus its weight; a weightless man has only the inertia to overcome, and the chances are that it will take a long time for his muscles to grow accustomed to the fact. “What would be a normal step on earth would . . . send the ‘stepper’ sailing across the cabin or somersaulting wildly in the air,” the Air University Command and Staff School study declares. “A mere sneeze could propel the victim violently against the cabin wall and result in possible injury.”
Actually, very little is known about weightlessness. Until a few years ago, it was something that man had experienced only in very special circumstances, and then for no more than a fraction of a second—at the start of a roller coaster’s plunge, for example, or at the instant of going off a high diving board. With the man-in-space program moving along, however, weightlessness has been deliberately arranged in certain flights undertaken at the Air Force School of Aviation Medicine, in San Antonio; in these, jet planes, flying along a prescribed parabolic course, manage to escape the effects of gravity for as long as thirty seconds. The exposure to weightlessness, brief as it is, has had widely varying effects on the airmen. “The sensation can best be described as one of incredulity, or even slight amusement,” a colonel with a great deal of flying experience has reported, ascribing this reaction to “the incongruity of seeing objects and one’s own feet float free of the floor without any muscular effort.” Another airman, who was a gymnast in college, was reminded of “having started a back flip from a standing position and then become hung up part way over—looking toward the sky but not completing the flip.” The sensation, he said, gave him “no particular enjoyment or dislike”—only “a feeling of indifference.” Other airmen have found the experience extremely unpleasant—accompanied by nausea, sleepiness, weakness, sweating, and/or vertigo—and, to confuse matters, still others have discovered that their reactions differ on different flights. All told, one expert estimates, about a third of the subjects regard weightlessness as “definitely distressing,” while a fourth regard it as “not exactly comfortable.”
The experts realize, of course, that weightless voyages lasting a good deal longer than half a minute would have physical and mental results that can only be guessed at now. “Most probably, nature will make us pay for the free ride,” one scientist has said, almost superstitiously. For one thing, a long trip would raise hob with a man’s muscles. In any earthly condition of inactivity, no matter how extreme, they still have the job of resisting gravity, and without this they are bound to grow flabby. Moreover, the space man’s sense of balance would be thrown out of whack; this sense is governed by a liquid in our inner ear, and without gravity that liquid, floating freely in the chambers of the ear, could not be relied on to do its work. Not only would the space man be uncertain of where he was in his cabin at any particular moment, I learned from Lieutenant Colonel Robert Williams, a consultant in neurology and psychiatry to the Surgeon General, but he would run the risk of losing his “body image.” This image, Dr. Williams told me, is the deeply rooted conception that we all have of ourselves as a physical entity; it is one of the major constituents of our equanimity. “Without a body image,” he went on, “a person has difficulty in determining what is inside oneself and what is outside, in distinguishing one’s fantasy life from one’s real environment. In losing it, we face a possible complete disruption of personality.”
Assuming that the space traveler returns to earth with his personality undamaged, other difficulties may be in store for him. “A man who has been weightless for a couple of weeks would find it as hard to move around as a hospital patient taking his first steps after a long siege in bed,” Dr. Savely told me. “If he were to travel in a cooped-up posture over a long period of time—and, for all we know now, that may be the only way he can travel—the whole architecture of his skeleton might change. Of course, we simply cannot allow that to happen.” In view of such forebodings, it is not surprising that the man-in-space people are seeking to avoid weightlessness, altogether or in part, by developing an artificial substitute for gravity, but they don’t seem to have made much headway. According to one scheme, the space man’s cabin would be attached to the rocket by a long cable and would be swung around it continuously, thus creating a field of gravity that would restore the passenger’s weight and, presumably, his efficiency. Discussing this in the Scientific American, Dr. Heinz Haber, of the Air Force School of Aviation Medicine, guesses that it would work only as long as the passenger stood absolutely still. “Every voluntary movement,” he writes, “would give the traveler the peculiar illusion that he was being moved haphazardly.” Another approach would be to have the astronaut tread a magnetized floor in iron shoes, but Dr. Haber isn’t too sanguine about this one, either. Not only would the magnetism throw off the ship’s electronic instruments, he points out, but it would “probably add to the traveler’s confusion, for while his shoes would be attracted to the floor, his nonmagnetic body would not.”
If the problem of weightlessness is solved, the pilot may know where he is in the cabin, but, owing to the vastness of space, he will still be uncertain of his whereabouts in the universe. This will be so, I was told, regardless of how informative the ship’s instrument panel may be. A trip to Venus, around it, and back to earth would require a million miles of travel every day for three years, Dr. Seville Chapman, director of the Physics Division of the Cornell Aeronautical Laboratory, told me, and went on to say that the human mind may find the simple statistics of space flight baffling. “Suppose I tell you that our nearest star, Proxima Centauri, is four and two-tenths light-years away, a light-year being the distance a beam of light travels in twelve months at about a hundred and eighty-six thousand three hundred miles per second,” he added. “Just what does that mean to you?” (Compared to such destinations, writes Major General Dan C. Ogle, the Surgeon General of the Air Force, our present space-travel aspirations—merely reaching the moon, for example—are “relatively provincial,” taking in no more than “our own back yard.”) Certainly nothing the space man will see is going to make him feel at home. He will have no horizon to look out on; in fact, he will be engulfed by blackness, for space has none of the air particles that diffuse the sun’s rays to give us our daylight. In this nightlike setting, the sun itself will be painfully brilliant, and the constellations will seem to be spread out flat and to take on bizarre shapes. There will be stars both above and below, but they will not twinkle, for twinkling is caused by the same air particles. They will appear, rather, as steady points of light, and in their true colors— red, blue, yellow, white.