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History of Research in Space Biology
and Biodynamics
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- - PART III -
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- Later Subgravity Studies at
Holloman, 1954 - 1958
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- [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
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- 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
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- 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
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- 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
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- 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
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- 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
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- 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
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- 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
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- 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
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- 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
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- 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.
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- 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
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- 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
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- 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
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- 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
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- 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
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- 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
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- 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
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- 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
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- 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
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- 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
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