BALLOONS

Biological and medical experiments carried out on balloon flights, both manned and unmanned, antedate the establishment of NASA. Aside from the early use of balloons in flights that could be called simply flight-survival studies, balloons have made important contributions to our present knowledge of the effects of cosmic radiation and to various aspects of space travel.

The achievements of the Strato-Lab and Man High series by the U.S. Navy and Air Force include a wealth of information on balloon travel and on the survival of man at altitudes close to and above 100000 feet. Generally, balloon launches of animals, which reached a maximum in 1953 when 23 balloons were released, have established the feasibility of a program of extended manned balloon flights to high altitudes.

Atmospheric life studies outside the area of cosmic radiation effects have been comparatively few. Results from two manned flights, Strato-Lab I and II, indicate that the flights did produce pronounced changes in white blood cell count; however, the data suggest that these changes were due to psychological rather than physical stress. Exposure to altitudes above 90000 feet for a total of 62 hours did not produce any general behavioral change in two Java monkeys, according to other balloon flights. Many of these flights were effective in testing equipment, telemetering devices, and in pointing the way for other flights.

Stratoscope I and II, originally undertaken by the Office of Naval Research (ONR), are projects involving various astronomical observations with the aid of a balloon-borne telescope and television and camera systems. NASA cooperated with ONR on Stratoscope II (36-inch telescope compared with Stratoscope I's 12-inch telescope) which has already resulted in significant discoveries about the nature of the planets and stars. Water vapor has been identified in the atmosphere of cool red stars and an analysis of the Martian spectra showed a greater abundance of carbon dioxide than had previously been believed. Since the balloon-borne telescope was carried beyond Earth's obscuring atmosphere, the Stratoscope projects have yielded valuable photographs of the Sun, stars, and various planets.

ROCKETS AND SATELLITES

Historically, biological experiments aboard rockets and satellites have been limited to a "piggyback" and "noninterference" basis on military rockets. For the past few years, however, as the effort toward manned space flight leading to lunar and Martian landings increased, more attention was devoted to experiments designed to show the effects of the space environment on living systems. As in the balloon flight programs, the U.S. Army, Navy, and Air Force played an important role, reaching what might be considered a high point with the successful launch and recovery of a ballistic rocket experiment with monkeys Able and Baker. Aerobee rockets as well as Thor IRBM's carried biological payloads consisting of mice and monkeys on six launches, contributing to our knowledge of the effects of weightlessness and radiation on higher animals.

Van der Wal and Young ([ref.78]) used Thor-Able combinations to serve as boosters for lifting a 20-pound biocapsule to a peak altitude of 1400 miles and over a distance of about 5300 miles from Cape Canaveral to the west coast of Africa. Weightlessness was attained for a period of almost 40 minutes. During reentry into the atmosphere, a peak deceleration of about 60 g was reached. Each of the three capsules flown carried one mouse (Mouse-in-Able); two of the mice were instrumented for heart-rate telemetry. Although all three mice were lost, the two experiments with Laska and Benji yielded physiological results.

The experimenters designed effective instrumentation for registering the electrical activity of the mouse's heart through a single commutated telemetry channel. Records were obtained for both animals during various portions of the flight. The results indicate that both animals were alive when the nose cones hit the water.

Two South American squirrel monkeys (Gordo and Baker) and a rhesus monkey (Able) were launched into space from Cape Canaveral in 1958 and 1959 by U.S. Army Jupiter missiles. The vehicles reached speeds of approximately 10000 mph and altitudes of 300 miles on flights which lasted about 15 min.

Time courses of cardiac and respiratory rates ([ref.80]) of the two squirrel monkeys showed that the noise of the engine at liftoff immediately produced an increase in their heart rates. Respiration also increased temporarily, but slowed later with increasing acceleration. Heart rates fluctuated considerably during launch acceleration, which reached about 15 g at cutoff.

The period of free flight and weightlessness was characterized by pronounced fluctuations of heart activity in the postacceleration phase. Thereafter, the heart rate of Baker remained relatively constant, whereas the cardiac activity of Gordo fluctuated markedly and decreased slowly almost to the end of his flight. Slight changes, which were transient and not pathological in nature, were also noted in the electrocardiogram. Gordo's respiration was very shallow during maximum launch acceleration, when Baker's reached its highest value, only to be approximated again during reentry when forces of about 35 g were encountered.

Able's cardiac and respiratory rates indicated that, after an initial startle reaction, the heart rate dropped transiently and then increased steeply, reaching a maximum of 259 during the 10-second interval at peak acceleration. Respiration increased only slightly throughout the launching phase. There was a period of tachycardia during postacceleration weightlessness, after which the heart rate declined steadily and was disturbed only by several startling missile events. At the end of the subgravity phase, Able's cardiac rate was slightly below normal.

Although the periods of high g force and free flight were short, the extremes were considerable, and the changes from one state to the next were rapid. In spite of this, the cardiovascular, hemodynamic, and electrocardiographic phenomena were remarkably well maintained. Apparently the animals were not in serious plight at any time. That psychological factors entered into the observed phenomena is clearly evident from the increase in cardiac rate associated with the noise of the engine prior to liftoff and also from the cinematographic record of facial expressions. Nevertheless, the integrated responses indicated that the animals' physiological states remained sufficiently normal to insure a safe flight.

LITTLE JOE FLIGHTS

The first step in an attempt at animal verification of the adequacy of the Mercury flight program was the development of two tests by NASA in collaboration with the U.S. Air Force School of Aviation Medicine in which there would be a biomedical evaluation of the accelerations experienced during the abort of a Mercury flight at and shortly after liftoff. These flights were launched at the NASA Wallops Station with a Little Joe solid-fuel launch vehicle.

Two Little Joe launches were made with activation of the escape rockets during the boost phase to secure maximum acceleration; only a brief period of weightlessness was attained. The first launch was on December 4, 1959, and the other on January 21, 1960. A 36 by 18-inch sealed, 125-pound, cylindrical capsule containing the subject, an 8-pound Macaca mulatta, the necessary life-support system, and associated instrumentation was flown in a "boilerplate" model of the Mercury spacecraft. The rhesus monkeys were named "Sam" and "Miss Sam."

The flight profile included maximum accelerations of about 10 to 12 g and periods of about 3 minutes at 0±0.02 g. The peak altitude obtained in the last ballistic flight was about 280000 feet. The experimental capsule was pressurized at 1 atmosphere with 100 percent oxygen at the start of the experiment and fell to just below a half atmosphere of oxygen due to breathing during flight. The capsule temperature was kept between 10° and 20°C in both flights.

The measurements taken from the rhesus monkeys were the electrocardiogram, respiration, body temperature, eye movements, and bar pressing, but only partial results were obtained in the first flight. Oxygen tension, total pressure, capsule temperature, and relative humidity were recorded. Both animals were recovered alive and did not show pathologic alterations in their physiologic and psychological reactions.

MERCURY ANIMAL TEST FLIGHTS

In the Mercury animal test program a Redstone missile carried the chimpanzee Ham on a ballistic flight to a height of 155 miles to provide animal verification of the success with which the Mercury system could be applied to manned flight. The male chimpanzee was trained to perform a two-phased reaction task during the 16 minutes of flight. The chimpanzee Enos was put into orbit for 3 hours and 20 minutes. Results of the two flights gave the following information:

1. Pulse and respiration rates during both the ballistic (MR-2) and the orbital (MA-5) flights remained within normal limits throughout the weightless state. Effectiveness of heart action, as evaluated from the electrocardiograms and pressure records, was also unaffected by the flights.

2. Blood pressures, both arterial and venous, were not significantly changed from preflight values during 3 hours of the weightless state.

3. The performance of a series of tasks involving continuous and discrete avoidance, fixed ratio responses for food reward, delayed response for a fluid reward, and solution of a simple oddity problem was unaffected by the weightless state.

4. Animals trained in the laboratory to perform during simulated acceleration, noise, and vibration of launch and reentry were able to maintain performance throughout an actual flight.

From the results of the MR-2 and MA-5 flights, the following conclusions were drawn:

1. The numerous objectives of the Mercury animal test program were met. The MR-2 and MA-5 tests preceded the first ballistic and orbital manned flights, respectively, and provided valuable training in countdown procedures and range monitoring and recovery techniques. The bioinstrumentation was effectively tested and the adequacy of the environmental control system was demonstrated.

2. A 7-minute (MR-2) and a 3-hour (MA-5) exposure to the weightless state were experienced by the subjects in an experimental design which left visual and tactile references unimpaired. There was no significant change in the physiological state or performance of the animals as measured during a series of tasks of graded motivation and difficulty.

3. Questions were answered concerning the physical and mental demands that the astronauts would encounter during space flight, and it was shown that these demands would not be excessive.

4. It was also demonstrated that the young chimpanzee can be trained to be a highly reliable subject for space-flight studies.

The suborbital ballistic flight of Ham on January 31, 1961, was the prelude to Alan R. Shepard's suborbital space flight, while the orbital flight of Enos on November 29, 1961, preceded the orbital flight of John H. Glenn.

The fact that we now categorize these events as belonging to the rather distant past, although they occurred only about 4 years ago, serves to emphasize the pace of development in the exploration of space. While the chimpanzee program may pale in the light of subsequent successes, its scientific and technological contribution should not be overlooked.

The significance of this project can be fully appreciated, and its contribution judged, only by considering the lack of knowledge existing at the time of its conception. In addition to its essential training function, this project verified the feasibility of manned space flight through operational tests of the Mercury life-support system. It demonstrated that complex behavioral processes and basic physiological functions remained essentially unperturbed during brief exposures to space flight. The Mercury chimpanzee program marked the first time that physiological and behavioral assessment techniques were combined for evaluating the functional efficiency of the total organism in space.

Perhaps the ultimate contribution of this program was in providing the framework of knowledge upon which future scientific experiments on biological organisms, exposed to flights of extended durations, must be based. Biosatellite experiments designed to seek more subtle and elusive effects of prolonged space flight on biological functioning will require even more refined and difficult techniques, but will depend heavily on the groundwork laid in these early steps of Project Mercury.

A summary of the more important animal suborbital and orbital flights during the period 1957 to 1964 is presented in table VII.

In another NASA-supported flight, NERV 1, various experiments were carried in a suborbital flight of 20 minutes. Neurospora molds showed a surprisingly high level of mutation, but the control molds also had high rates.

The Discoverer XVII and XVIII flights, to which the Air Force contributed, resulted in many interesting findings relative to the responses of living systems to space flight. On the Discoverer XVII flight, samples of human gamma globulin and rabbit antiserum specific for human gamma globulin showed an increase in reactivity, and samples of synovial and conjunctival cells showed no changes in their cytological characteristics.

Discoverer XVIII was launched during a massive solar flare which lasted for the first 13 hours of the 48-orbit, 3-day flight. Neurospora conidia, nerve tissue, algae, human bone marrow, eyelid tissue, gamma globulin, and cancer cells were put in orbit. The results indicated that biological specimens may be able to withstand radiation from solar flares with a minimum of shielding and that aluminum shielding may be better than lead.

In 1949, the U.S.S.R. began a systematic, uninterrupted research program in biological space experimentation. They have studied the effects of physical stress, immune reactions, psychobiology and behavior, genetics, and responses to environmental factors such as spacecraft dynamics and ambient radiation. The organisms and biological materials included tobacco mosaic and influenza viruses; T2 and T4 bacteriophage; Bacillus aerogenes; lysogenic bacteria; Clostridium butyricum; Escherichia coli; actinomycetes; yeasts; Chlorella pyrenoidosa; seeds of fir, pine, onion, corn, lettuce, wheat, cabbage, carrot, buckwheat, cucumber, beet, Euonymus, fennel, mustard, pea, broad bean, tomato, and nutmeg; Tradescantia paludosa; Ascaris eggs; snail spawn; Drosophila melanogaster; loach roe; frog eggs and sperm; guinea pigs; mice; rats; hamsters; rabbits; dogs; monkeys; human and rabbit skin; HeLa tissue cultures and other tissues (refs. [ref.167] and [ref.168]).

THE NASA BIOSATELLITE PROGRAM³

The space environment offers a unique opportunity to study the basic properties of living Earth organisms with new tools and opens up new areas of research for which biological theory fails to provide adequate predictions. Unique components of the space environment of biological importance are weightlessness or greatly decreased gravity, the imposition of an environment disconnected from Earth's 24-hour rotation (particularly its effect on biorhythms), and cosmic radiation with energies and particle sizes unmatched by anything produced artificially on Earth ([ref.169]).

As progress is made in the manned exploration of space, the biological effects of its unique environmental factors become of greater importance. It is essential to determine the effects of space environment on man's ability to perform physical and mental tasks. In addition, it is necessary to develop those systems required for his survival and for his physiological and psychological well-being, both in space and in his subsequent resumption of normal life patterns. Despite nearly a century of research and development in environmental physiology, a number of phenomena will be encountered in long-term space flight with which we have had neither the experience that would enable us to predict the effects nor to develop the necessary protective or remedial measures ([ref.170]). Many of the experimental programs in bioscience are being carried out or planned so that the deleterious effects of these phenomena may be determined, predicted, or avoided before they are encountered in manned flight.

Biological experimentation has been carried out in orbiting spacecraft by Soviet and American scientists preparatory to manned space flight. These first-generation exploratory experiments had the following objectives:

1. To discover whether complex organisms could survive space conditions and to test life-support systems

2. To determine whether complex organisms (dogs and primates) could survive launch, orbital space flight, reentry, and recovery

3. To determine the effects of space radiation and any obvious effects of weightlessness on biological organisms

These biological studies indicate that manned space flight was practicable, and the various cosmonaut and astronaut flights have proven the validity of the results.

The National Academy of Sciences' Space Science Board summer study ([ref.171]) recommended that—

NASA should exploit special features of the space environment as unique situations for the general analysis of the organism-environment relationships including, especially, the role environmental inputs play in the establishment and maintenance of normal organization in the living system. NASA should support studies in ground-based and in orbiting laboratories [biosatellites] on the biological effects of gravity fields both above and below normal. This should be considered a major responsibility of NASA in the area of environmental opportunities. NASA should support studies of biological rhythms in plants and animals including man as part of its effort in environmental biology. Investigate by observation of rhythms in organisms in space in (a) polar and equatorial low orbits; (b) orbits less than, equal to and greater than 22,000 miles. Properly designed experiments should be conducted to explore the effects of different environmental factors when these impinge simultaneously on test organisms.

The Panel on Gravity of the Space Science Board ([ref.67]) stated that the major effects of low gravity would be expected in heterocellular organisms that develop in more or less fixed orientation with respect to terrestrial gravity and which respond to changes in orientation with relatively long induction periods, including the higher plants. On the other extreme are the complex primates which respond rapidly, but whose multiplicity of organs and correlative mechanisms make the occurrence of malfunction and disorganization probable, but not certain. The Panel recommended emphasis on early embryogenesis and histogenesis, particularly of plants during exposure to low gravity, and anatomical studies after low gravity. They stated that perturbations of the environment to which the experimental organism is exposed must be limited or controlled to reduce uncertainties in interpretation of results. At the same time, the introduction of known perturbations may assist in isolating the effects due solely to gravity. Ground-based clinostats and centrifuges should be used in conjunction with the experiments, and an attempt should be made to extrapolate effects of low gravity with the clinostat.

The study of the effects of unique or unknown space environmental factors will probably yield unexpected results which may drastically modify future technical approaches. The results from these biosatellite studies will have broad application to longer term, manned space flight, including manned space stations and lunar and planetary exploration.

The biosatellite program is a second-generation series of carefully planned and selected experiments, including some highly sophisticated experiments which have required several years of baseline study and equipment development. These orbiting recoverable biosatellites will provide opportunities for critical testing of major biological hypotheses in the areas of genetics, evolution, and physiology.

The scientific community showed great interest in the biosatellite program, and scientists from universities, industry, and Government have submitted 185 flight experiments involving primates and other mammals, vertebrate and invertebrate animals, micro-organisms, and plants.

The selected biosatellite experiments include studies at the cellular, tissue, and organism levels, including embryological development and growth experiments at the tissue level and physiological, behavioral, reproductive, and genetic studies at the organism level. The experiments are divided into six categories:

1. Primates

2. Mammals (nonprimate)

3. Animal, cellular, and egg

4. Plant morphogenesis, photosynthesis, and growth

5. Biorhythm

6. Radiation

Twenty experiments have been selected for flight to study the effects of weightlessness and decreased gravity during 3- to 30-day orbital periods. The experiments include a wide variety of plants and animals from single-celled organisms to higher plants and animals. The effects of weightlessness on the primate will be studied, especially the central nervous, the cardiovascular, and the skeletal systems during 30-day orbits.

Experiments have been selected to study the genetic and somatic effects of weightlessness combined with a known source of radiation (Sr⁸⁵) to determine if there are any antagonistic or synergistic effects ([ref.172]). Experiments are also included for studying the effects of the unique environment of the Earth-orbiting satellite and removal from the Earth's rotation in relation to biological rhythms of plants and animals.

Six biosatellites are included in the presently approved program, with the first flight in 1966. They will be launched from Cape Kennedy by the improved two-stage, thrust-augmented Thor-Delta into a nearly equatorial circular orbit at an altitude of 180-200 miles for periods up to 30 days. Recovery will be by Air Force airplane during capsule/parachute descent. The spacecraft weigh 1000-1200 pounds, have a 280-pound recoverable capsule and, while in orbit, will not experience greater than 1/10000 g of acceleration. The life-support system will provide an environment at sea-level pressure of 80 percent nitrogen, 20 percent oxygen, and no more than 0.5 percent carbon dioxide with a temperature of 75°F ±5°F.

All experiments are in various stages of development or testing and flight test hardware has been and is being constructed. The experiments and hardware are being subjected to preflight tests simulating launch and recovery stresses. Rhesus, pigtail, and squirrel monkeys have been subjected to the dynamic forces of the simulated flight under conditions of complete, partial, and no restraint. Three types of centrifuges have been used to simulate the flight profile. Primates were fully instrumented with deep brain electrode implants, implanted catheters, and other implanted sensors. During centrifugation, motion pictures were taken. These primates were semirestrained in form-fitted couches which allowed movement of the body while facing the accelerative force in a ventrodorsal position (eyeballs in). In this series of tests, all primates were normal following the tests and exhibited no unusual behavior or effects. X-rays showed that implanted catheters and electrodes remained in place, and there were no movements causing tissue damage. However, when the primates were placed with their backs toward the accelerative force, dorsoventral (eyeballs out), the animals suffered visible damage. At 6 g there was no visible stress, but at 8 g swelling of the lower eyelids was noticeable. At 11 g both eyelids were swollen shut. In the biosatellite program, primates will be placed in the semirestraint couches in a position facing accelerative forces, ventrodorsal (eyeballs in), to prevent these effects.