History of Research in Space Biology and Biodynamics
Later Subgravity Studies at Holloman, 1954 - 1958
[36] The sum total of subgravity research accomplished prior to 1954 still was not great, but it allowed certain tentative conclusions to be drawn. There seemed to be no major respiratory or circulatory hazards resulting from weightlessness, although Doctor David G. Simons carefully pointed out that respiratory and circulatory complications might arise as a secondary effect of "emotional and autonomic reactions which are essentially the same whether caused by weightlessness, a rough sea, or an obnoxious mother-in-law." Simons generalized further, on the basis of studies up to and including Von Beckh's, that subgravity should normally produce "minimal discoordination and no disorientation... as long as the subject retains tactile and visual references."12
What was needed now was a much greater accumulation of detailed test data to verify or revise preliminary conclusions and to reveal still other possible effects of subgravity. Better test instrumentation was also needed, especially to record all the variations of gravity force from true zero-gravity up to a normal one-g state. This would be of great help to any pilot attempting to fly a subgravity trajectory. In addition, most suggestions for future space stations have provided for some form of rotation in order to avoid absolute weightlessness, through the artificial creation of a centrifugal force, but nobody knew exactly how many hundredths of a g must be generated to produce what results. It might also turn out that no rotation at all is needed; but in any case there was an urgent requirement for research data on this and other ramifications of the subgravity question.13
By the same token, there was ample reason to establish a formal subgravity program at Holloman within the framework of the Space Biology Branch of the Aeromedical Field Laboratory. Unlike the earlier V-2 and Aerobee flights, the present program is part of the Center's own project workload. The Aeromedical Field Laboratory had been founded in 1951 as a field station for project scientists operating from the Aero Medical Laboratory at Wright Field, but in January 1953 it became a function of the local Center (then known as Holloman Air Development Center), and in October 1953 subgravity studies were specifically included in the Holloman laboratory's mission. In the following year, 1954, work on subgravity actually got underway as Task 78501 of the newly created Project 7851, Human Factors of Space Flight. Doctor (at that time Major) David G. Simons was project officer of Project 7851, as well as head of the laboratory's Space Biology Branch. Technical Sergeant John T. Conniff was the orginal task scientist for Task 78501, Subgravity Studies. 14
For some time, with funds and manpower both limited, the main task activity consisted of planning and preparation for an ultimate test program. Sergeant Conniff's subgravity duties were not so engrossing as to prevent him from continuing as head of the laboratory's Electronics Unit;15 indeed the latter position was presumably of advantage to him in collecting instrumentation for the subgravity program. Nevertheless, a preliminary, aircraft flight took place at least as early as September 1954, using a T-33, to evaluate some of the problems involved in flying [37] a parabolic subgravity trajectory. More flights were made early the following year with an F-89, again mostly for evaluating techniques and instrumentation. 16
The program was not really intensified until after the assignment of Captain Grover J. D. Schock as task scientist on 1 July 1955. Captain Schock--whose contributions to subgravity research later qualified him as the first known scientist to receive a Doctor of Philosophy degree in space physiology--initiated subgravity flights in an F-94C aircraft in the fall of 1955, using himself as one of the various test subjects. The F-94C became the standard test vehicle for subgravity research, and Task 78501 remained the primary duty of Captain Schock until the beginning of 1958, when Von Beckh took over as task scientist. Captain Schock then branched out into other lines of activity for the Aeromedical Field Laboratory, but without abandoning his previous interest and participation in the subgravity program. Moreover, he kept one special foothold as task scientist for Task 78530, Psychophysiology of Weightlessness. This was a task of the recently-established Project 7857, Research in Space Bio-Sciences. It is not concerned with the aircraft subgravity flights at Holloman, but with certain research to be done by outside investigators on a contract basis as well as a limited amount of "in-house" effort. 17
The F-94C flights, which have been the primary activity of Task 78501, are capable of giving subgravity trajectories of more than thirty seconds in duration; and more than one such trajectory or "run" can be scheduled on a single flight. The amount of actual zero-gravity is always considerably less, although exposures have increased steadily. Early in 1958, the maximum zero-gravity obtainable in a test trajectory was about twenty-two seconds, and even this exposure was not continuous but was interrupted by momentary lapses into some minute fraction of positive or negative g-force. Nevertheless, the period was long enough for many types of experimentation, and it compared favorably indeed with the two or three seconds of true weightlessness achieved on some of the very earliest parabolic test flights.18
This advance is of course due to improvements both in flight techniques and in test instrumentation. One item of instrumentation still in use when Captain Schock joined the program was a golf ball dangling on a string from the aircraft canopy--a gadget that accurately showed when pure weightlessness had been achieved but could not measure degrees of subgravity. The standard aircraft g-meter was not very satisfactory, either, for instrumenting subgravity flights. However, Captain Schock devoted a major part of his attention to the instrumentation problem. More precise methods have since been devised, using a combination of differently-placed accelerometers. Information on the exact g-forces being experienced is constantly relayed to the aircraft pilot by two sensitive microammeters installed in his field of vision, and the same information is carefully synchronized with a film record of the test subject's reactions.19
Unfortunately, the subgravity program was also afflicted with more than its share of aircraft trouble. Apart from normal maintenance problems, the F-94C aircraft used in the program developed such special troubles during subgravity flights as loss of oil pressure, loss of hydraulic fluid, and "sticking" of the trim tab motor. These difficulties, as well as the presence of extra equipment mounted inside the aircraft, caused a good bit of worry to flying safety and maintenance officers, and required suspension of tests on several occasions. But in the end all the difficulties were shown to be of little importance or else were corrected. Both Lockheed, the aircraft manufacturer, and Pratt-Whitney, the engine manufacturer, were extremely helpful in finding solutions. Moreover, the difficulties over hydraulic fluid and oil pressure suggested some profitable investigations on the behavior of fluids under subgravity conditions, shaking them or forcing them from a squeeze bottle in subgravity flight.20
Still another problem that arose was that standard microphones in the F-94 (and earlier in the F-89) were unable to transmit clear messages between pilot and test subject during subgravity. This led to research on the problem and installation of a more satisfactory type of microphone. As a result, Captain Schock is now able to conclude, "Voice communications in future space vehicles should present no problem." 21
It is worth noting that so many materiel problems of subgravity flight were discovered in the course of human factors research. Nevertheless, the main interest of the subgravity program does not lie in the effects of subgravity on aircraft parts and equipment but in the reactions of human test subjects. And it is well to note, first of all, that not all human subjects reacted the same way. Some have [38] positively enjoyed the gravity-free state, while others have on occasion felt extreme motion sickness with nausea and vomiting. Among the former can be included Sergeant Conniff, the original task scientist, and Captain Druey P. Parks, who has participated in this as in all other programs of the Space Biology Branch. Among those who have suffered varying amounts of discomfort, Captain Schock definitely includes himself. It is perhaps significant that one who professes no distaste for subgravity is Captain Joseph W. Kittinger, Jr., better known as the test pilot for the Man-High (I) balloon flight, who piloted a great many subgravity trajectories at Holloman before his recent transfer to Wright Air Development Center. In his case, it is likely that a broad previous flying career helped prepare him for the experience, although no number of flying hours is any guarantee in itself against feeling ill at ease during a subgravity exposure.22
The apparent existence of wide variations in human tolerance suggests that one criterion for selection of crews in space travel may well be a comparison of monitored responses during experimental subgravity exposures. However, still more information is needed on these varying personal sensations. The sickness felt by some may be related to the rapidly changing g-forces encountered in a complete test flight, including the high acceleration and deceleration that sometimes mark the plane's entry to and exit from the subgravity parabola. In that case, the same symptoms might not be associated with long-duration, continuous subgravity exposures. On the other hand, those who easily endure thirty seconds of subgravity might conceivably do less well with a three-minute--or three-month--dose of the same thing. Laika's experience is encouraging in this respect, but hardly conclusive.
The Holloman subgravity flights have also featured a variety of sensomotor performance tests. These indicate that subgravity need not seriously impair a subject's ability to touch his nose with his finger tip, mark x's in a row of squares, or perform other similar operations--provided always that he retains a visual frame of reference, and provided also, of course, that he has not first become violently ill with motion sickness. This conclusion closely parallels those tentatively drawn from the earlier test programs of Ballinger, Von Beckh and others. Neither does eating peanut brittle offer major problems during weightless trajectory, as long as the food is first well masticated and then forced to the back of the mouth where the swallowing reflex goes into action without regard to gravity. Drinking seems to require use of a squeeze bottle, cups and glasses being quite useless during weightlessness. Water must be forced to the back of the mouth tongue, but again the swallowing reflex is unimpaired.23
A somewhat different variety of experiment has demonstrated that human subjects, deprived of normal visual references, will perceive oculogravic illusions such as "apparent linear motion of a fixed 'target' during a ballistic [Keplerian] trajectory." For these tests both the subject's head and the "target"--a small luminous cross--were placed under a large and ominous-looking black hood. The illusion was always most pronounced during the periods of increased g-forces on entering and leaving the subgravity parabola. The target appeared to stabilize--though at a higher than normal position--during the weightless phase itself, except for certain oscillations that were attributed to the failure of the test aircraft to maintain an even weightless trajectory.24
When Doctor von Beckh joined the Holloman program, he brought with him as a carryover from his work in Argentina , special interest in the effects of subgravity on ease of recovery from acceleration-induced blackout or greyout. At Holloman, he has initiated flights designed to produce subgravity either just after or just before exposure to a force of roughly four g's, with a peak of five or six. This procedure duplicates the type of conditions to be met in takeoff and re-entry of manned space vehicles. The test services has only recently started, but when further advance should yield important research data.25
Nor have animal subjects been forgotten in the Holloman test flights. The current pet of subgravity research--at least in the Free World--is the familiar cat, which is of interest for its highly developed vestibular function. It is actually more reliant on this function for balance an orientation than are human beings. The cat is also noted for its reflex ability to land squarely on all fours even after being upside down, and tests were conducted to determine how this righting reflex operates during subgravity. Judging by the test results, it does not work very well. In order to examine the matter more closely, Captain Schock obtained certain cats that had undergone operations removing the vestibular apparatus wholly or partially. When these cats were tested in the same manner, it appeared that animals still [39] having even partial vestibular function were confused. On the other hand, animals wholly deprived of this function and accustomed to do without it remained fully oriented and in possession of normal reflex responses unless their eyes were covered. This last observation confirmed once again the critical importance of visual orientation.26
Although the test program has centered primarily around subgravity trajectories flown in jet aircraft, other tests have been performed in simulated subgravity conditions at ground level. Some of the reactions of a human subject immersed in water are similar to those encountered in a subgravity state; for instance, external pressure on the skin is so evenly distributed around the body surface, when under water, that this pressure is perceptible barely if at all, just as in a weightless condition. Accordingly, in the spring of 1957, Captain Schock staged a series of experiments at the indoor pool of the El Paso Young Men's Christian Association, with the subject on a rotating seat in eight feet of water and blindfolded. Later in the same year, underwater experiments were conducted in the pool of the New Mexico School for the Visually Handicapped in Alamogordo. Such tests have demonstrated an impairment of orientation somewhat like that experienced in aircraft experiments where the subject lacks normal visual cues. In one type of underwater experiment, subjects were tilted as much as twenty-two degrees before perceiving the tilt. The underwater tests have also made a definite contribution to the methodology of subgravity research, and offer the advantage of more prolonged exposure to test conditions than a comparable aircraft trajectory.27
The Aeromedical Field Laboratory has worked in close cooperation not merely with the owners of indoor pools but also with Air Force and private researchers interested in subgravity studies. The School of Aviation Medicine, in particular, has been conducting an active subgravity program at Randolph Air Force Base, Texas. Under the principal direction of Dr. Siegfried J. Gerathewohl, this program in its present form dates from 1955; it, too, has been centered around subgravity test parabolas flown in jet aircraft. The general categories of testing and research have been much the same as in the Holloman program, but in some respects work at Randolph has pointed the way, while in other respects--notably instrumentation--the Holloman program has been generally more advanced. Fortunately, there has been little if any sign of the rivalry that has sometimes marred relationships between research programs of the Aeromedical Field Laboratory and related efforts of the Aero Medical Laboratory at Wright Field. There has in fact been a mutually profitable exchange of data and ideas, and though a spokesman for the School of Aviation Medicine has admitted that some overlapping research effort exists in subgravity studies, he went on to explain that this was actually "necessary because of the importance of the role that subgravity states will play in the immediate future."28
In addition to the current subgravity flights at Holloman and Randolph Field, there is at least one more active program of a similar nature now going on. It is in Soviet Russia, and though the Russians do not seem to have publicized aircraft subgravity flights to the same extent as their animal rocket experiments, they claim to have exposed human subjects to about the same period of weightlessness--forty seconds--that has been achieved by similar research in the United States.29
There has been no direct exchange of information between Holloman and Soviet researchers in this field. However, the cooperation of various outside institutions in the United States has been enlisted for the Holloman subgravity program on a contract basis. Researchers at the University of Illinois assisted Captain Schock's study of the vestibular mechanism in cats, performing the special vestibular operations on cats used in Holloman subgravity flights. They have also been working on techniques for attaching a recording device directly to the vestibular portion of the eighth cranial nerve. The Yellow Springs Instrument Company developed an airborne galvanic skin resistance meter, to permit continuous recording of resistance to electric impulses under stress in subgravity experiments. This instrument is at present being fitted at Holloman with the necessary in-flight recording apparatus. Cornell Aeronautical Laboratories, finally, made a theoretical study under contract of animal experiments that might be performed both in test vehicles now available for subgravity research and in more advanced vehicles that may become available for such studies later on. Additional contracts related to subgravity research have recently been initiated; the efforts mentioned, however, antedate the launching of even the first Russian satellite, and have been substantially or wholly completed.30
The same Russian satellite hastened the end of an Air Force-wide austerity [40]  drive that was unleashed in the first quarter of fiscal year 1958 and which unfortunately had administered a temporary setback to the Holloman subgravity program. The Air Force Missile Development Center was ordered to slash expenditures, and research projects generally had to suffer more than missile development. Subgravity studies suffered more than most: a directive issued on 27 August 1957 ordered "cessation of work"effective immediately. The "cessation" was soon clarified to refer only to work that cost money, such as the F-94C flights, which were calculated to use up sixty-three dollars an hour in operating expense without counting maintenance and overhead. Captain Schock in his official role as task scientist could still go swimming, and could plan and theorize to his heart's content. His specially-treated cats arrived from the University of Illinois right in the middle of the austerity drive, but he was able to toss them up and down in the laboratory, taking observations on how they fell; these observations could be compared later with the results of in-flight experiments, as soon as an aircraft was again made available.31
Subgravity contracts outstanding, were scaled down slightly at the same time but this occurred under a _____ order for five percent reduction in ture on effort-type contracts. All research programs were similarly affected and the impact on subgravity studies was barely noticeable compared with suspension of F-94C flights. Moreover on October 1957 austerity was ____, Center decision to the point of authorizing a small number of test flights, for the specific purpose of having the cat at last. Later still, with the appearance of the Russian satellites, austerity was abandoned altogether. By the start the subgravity program was back in full swing, although time lost could never wholly regained.32