Significant Achievements in Space Bioscience 1958-1964 Part 9

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 s.p.a.ce flight leading to lunar and Martian landings increased, more attention was devoted to experiments designed to show the effects of the s.p.a.ce 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 alt.i.tude 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. .h.i.t the water.

Two South American squirrel monkeys (Gordo and Baker) and a rhesus monkey (Able) were launched into s.p.a.ce from Cape Canaveral in 1958 and 1959 by U.S. Army Jupiter missiles. The vehicles reached speeds of approximately 10 000 mph and alt.i.tudes 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 p.r.o.nounced 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 a.s.sociated 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 a.s.sociated instrumentation was flown in a "boilerplate" model of the Mercury s.p.a.cecraft. 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 00.02 g. The peak alt.i.tude obtained in the last ballistic flight was about 280 000 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 s.p.a.ce 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 s.p.a.ce-flight studies.

The suborbital ballistic flight of Ham on January 31, 1961, was the prelude to Alan R. Shepard's suborbital s.p.a.ce 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 s.p.a.ce. 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 s.p.a.ce 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 s.p.a.ce flight. The Mercury chimpanzee program marked the first time that physiological and behavioral a.s.sessment techniques were combined for evaluating the functional efficiency of the total organism in s.p.a.ce.

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 s.p.a.ce 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 s.p.a.ce 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 ma.s.sive 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 s.h.i.+elding and that aluminum s.h.i.+elding may be better than lead.

In 1949, the U.S.S.R. began a systematic, uninterrupted research program in biological s.p.a.ce experimentation. They have studied the effects of physical stress, immune reactions, psychobiology and behavior, genetics, and responses to environmental factors such as s.p.a.cecraft dynamics and ambient radiation. The organisms and biological materials included tobacco mosaic and influenza viruses; T2 and T4 bacteriophage; _Bacillus aerogenes_; lysogenic bacteria; _Clostridium butyric.u.m_; _Escherichia coli_; actinomycetes; yeasts; _Chlorella pyrenoidosa_; seeds of fir, pine, onion, corn, lettuce, wheat, cabbage, carrot, buckwheat, cuc.u.mber, beet, _Euonymus_, fennel, mustard, pea, broad bean, tomato, and nutmeg; _Tradescantia paludosa_; _Ascaris_ eggs; snail sp.a.w.n; _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]).

Table VII.-_Orbital and Suborbital Animal Flights for 1957-64_

---------------------------------------------------------------- Year Animal subject Flight profile ---------------------------------------------------------------- United States ---------------------------------------------------------------- 1958 Mice _Wickie_, 1400 miles. None of the three _Laska_, and flights were recovered.

_Benji_ ---------------------------------------------------------------- 1958 Squirrel monkey 300-mile maximum alt.i.tude over a _Old Reliable_ 1300-mile distance via a Jupiter rocket. Not recovered.

---------------------------------------------------------------- 1959 Rhesus monkeys 300-mile maximum alt.i.tude over a _Able_ and _Baker_ 1500-mile distance via a Jupiter rocket. Recovered.

---------------------------------------------------------------- 1959 Black mice 500 seconds of weightlessness in Discoverer III via a Thor-Able rocket. The Discoverer vehicle did not go into orbit and the animals were lost.

---------------------------------------------------------------- 1959 Rhesus monkey 53-mile alt.i.tude in Little Joe.

_Sam_ Recovered.

---------------------------------------------------------------- 1960 Rhesus monkey 9-mile alt.i.tude in Little Joe.

_Miss Sam_ Recovered.

---------------------------------------------------------------- 1960 C-57 black mice 650-mile alt.i.tude over a 5000-mile distance via Atlas RVX-2A.

Recovered.

---------------------------------------------------------------- 1961 Chimpanzee _Ham_ 156-mile alt.i.tude over a 414-mile distance via a Redstone booster, Mercury capsule. Recovered.

---------------------------------------------------------------- 1961 Chimpanzee _Enos_ 2 Earth orbits. 183 minutes of weightlessnessat an apogee of 146 miles anda perigee of 99 miles.

Atlas booster, Mercury capsule.

Recovered.

---------------------------------------------------------------- Soviet Union ---------------------------------------------------------------- 1958 Dogs _Belyanka_ 280-mile alt.i.tude in hermetically and _Pestraya_ sealed cabin. Recovered.

---------------------------------------------------------------- 1959 Dog _Otyazhnaya_ Over 100-mile alt.i.tude. Recovered.

and a rabbit ---------------------------------------------------------------- 1960 Dogs _Belka_ and 16 Earth orbits (24 hours) via _Strelka_, 21 Sputnik V. First successful recovery black and 21 white of living creature from orbital mice flight.

---------------------------------------------------------------- 1960 Dogs _Pchelka_ and 16 Earth orbits (24 hours).

_Mushka_ s.p.a.cecraft destroyed during reentry.

---------------------------------------------------------------- 1961 1 dog, mice, 1 Earth orbit at an apogee of 155 guinea pigs, and miles and a perigee of 114 miles.

frogs Recovered.

---------------------------------------------------------------- 1961 Dog _Laetzpochka_ 1 Earth orbit. Recovered.

---------------------------------------------------------------- France ---------------------------------------------------------------- 1961 Rat _Hector_ 95-mile att.i.tude in a capsule boosted by a Veronique rocket.

Recovered.

---------------------------------------------------------------- 1963 Cat Felicette 95-mile alt.i.tude in a capsule boosted by a Veronique rocket. Over 5 min of weightlessness. Recovered.