Animals are indispensable to the space program. Their continued use could have many significant results. Those who are opposed to using animals in space should remember that space animals are treated humanely; they are necessary because results can be obtained from them that would be unobtainable from humans; and results from animal experiments can be applied to human systems. Therefore, NASA should continue to use animals in space research

White, Angela

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NASA Technical Reports Server

ANIMALS IN SPACE 
Angela White 
Animals have always been important to the space program. The United States 
flew monkeys in rockets between 1948 and 1952, ten years before the first orbit of the 
Earth by a man. The Soviet Union used dogs in their space program--a Soviet dog 
orbited the Earth in Sputnik II for a week in 1957. Monkeys were tested in the early 
years of NASA to determine whether it was safe for humans to fly into space. After Yuri 
Gagarin of the USSR became the first man to orbit the Earth, space animals were all 
but dropped in favor of using humans. However, recently, more animals are going into 
space, mainly for research purposes. On Spacelab 3 (SL-3), 26 animals experienced 
weightlessness and were studied thoroughly afterward, yielding valuable data. Ani- 
mals are a valuable part of the space program and NASA should support sending 
more animals in the future. 
The history of animals in space is not nearly complete. Such a history would 
show how well animals have been treated in the space program. Certain activist 
groups have advocated the total elimination of animal use in research, including 
space research, because of reports of inhumanity in too many research laboratories. 
A ban on animal use in research would decrease the number of animals killed and 
tortured each year in the nation. Such a ban, however, would severely cripple the 
space program. So far, NASA has an excellent record of humane treatment of ani- 
mals. For example, 24 rats and two squirrel monkeys were part of the last Spacelab 
mission, SL-3. Originally, the animals were sent only as a test of the research animal 
holding facility, or RAHF (fig. 1). 
Fortunately, the mission produced much more useful data than expected. It was 
discovered that the cage was an acceptable, nonstressful environment. One indica- 
tion that the RAHFs were nonstressful environments was the growth rate of the rats. 
Mission rats grew slightly less than rats in similar housing on the ground, and those 
rats grew less than rats in vivarium cages. However, according to Christopher 
Schatte, project scientist of the SL-3 life sciences payload, weight loss was probably 
caused by reduced energy requirements owing to microgravity, and also adaptation to 
a new environment. Another indication of low stress levels was the fact that the 
weights of certain organs, such as the spleen, brain, and heart, were within normal 
limits of variation. Other indications of chronic stress, such as adrenal hypertrophy and 
liver atrophy were mobserved. 
The monkeys were not analyzed postflight as thoroughly as the rats were, so 
data on life processes are not available for them. However, it was shown that squirrel 
monkeys will probably be acceptable in studies of space-adaptation syndrome, or 
space sickness. One monkey maintained normal eating behavior, but one showed 
decreased food intake during the first four days of the mission, then returned to normal 
eating behavior in the last three days. Videotape records of behavior showed 
decreased activity, followed by normal activity. Although no actual sickness was 
observed, these results are consistent with symptoms of sickness in monkeys cen- 
trifuged at 1.5 g (1.5 times normal gravity) and with human space sickness. No post- 
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flight abnormalities were observed. It is hoped that the squirrel monkey will be a good 
model for future studies. 
Although space research has been humane, some people are concerned about 
the necessity of animal research. If it is not absolutely necessary, then it should not be 
conducted. Animals are necessary to the space program and have been from the 
beginning of the program. Some experiments are performed on animals that could not 
be performed on humans. 
The rats on SL-3 are an example of vital studies possible only on animals. In 
order for the researchers to obtain data, the rats were sacrificed as soon as was possi- 
ble after landing. (There was a 12-hr gap between landing and sacrifice, due to a late 
change in landing site.) The detailed studies made of conditions such as bone and 
muscle loss would not be possible on humans. 
Future payloads of animals will be necessary in order to provide answers not 
available from human studies. Spacelab 4, renamed Spacelab Life Sciences 1 
(SLS-l), will carry the newly modified RAHF. (The RAHF was redesigned after it 
allowed particulates to escape on SL-3.) The RAHF will carry no animals, but will be 
tested to see if it allows particles to escape. SLS-1 will also carry jellyfish for 
observations not possible on mammals, such as graviceptor formation, graviceptor 
function, and swimming abilities. Graviceptors of jellyfish are easily observable, unlike 
those of humans. Studies of graviceptors and swimming behavior could give clues as 
to how graviceptors work in humans. Rats will go up on SLS-1; not in the RAHF, but in 
the animal enclosure module, or AEM (fig. 2). It is bigger than a single RAHF unit and 
holds five rats in the same area, or ten rats total in two areas. It has gone up on two 
previous missions and hopefully will go up on several others. Catheters attached to 
blood vessels near the heart in the rats will provide blood-flow data difficult, if not 
impossible, to obtain in humans. The rats will also be sacrificed postflight. 
On a future Spacelab mission, Spacelab Japan (SL-J), frog embryos will be 
fertilized in space in the frog embryology unit (FEU--fig. 3). Knowledge of embryology 
in space has potential applications in future projects, especially the Space Station. 
However, until the station is built, studies of embryology must be limited to animal 
embryos that develop quickly, which is necessary in a seven-to-ten-day shuttle flight. 
The rapid development of frog embryos makes this experiment possible, which would 
be impossible with humans. 
No matter how humane animal experiments are or how much data can be 
obtained which are unavailable from humans, all animal experiments would be use- 
less if their results were not applicable to humans in useful ways. Nonhuman (animal) 
life processes are appropriate models for human life processes, and useful data can 
be obtained from them. As indicated above, on the next Spacelab mission, SLS-1 , 
rats and jellyfish will be part of the payload. The jellyfish are included in order to study 
their graviceptors and methods of swimming in space. This is applicable to humans 
because of the lack of information we have on human graviceptors. If the mechanism 
of jellyfish graviceptors is studied, it might provide some clues to human graviceptors 
and how they work. 
136 
The rats will be monitored internally by implants in a flap in their backs. (The 
rats show no evidence of noticing these after about one day.) Information from the 
monitoring, such as blood flow, blood chemistry and rate of metabolism will provide 
more clues as to how the human body adapts to space, in good ways as well as bad. 
Postflight dissection will yield information on the inner ear, bone, bone marrow, 
spleen, muscles, and blood. Even the frogs on SL-J will provide embryology informa- 
tion that will be applicable to humans. Stages of development in frog embryos which 
are gravity-sensitive will be examined and analyzed. The data will then be compared 
with current knowledge of human embryos. Future flights such as these will provide 
much useful data. 
SL-3 has already produced results and data from the rat and monkey experi- 
ments, most of which will be applicable to humans, but some of which will have to be 
interpreted before being of use. The decrease in production of gamma interferon by 
spleen cells cultured postflight is one of several changes that were previously linked to 
stress and are now linked to the microgravity environment. This particular change has 
not been explained and may be, like the other hematology, immunology, and blood 
chemistry results, invalid, since they would be most susceptible to the 12-hr gap 
between landing and sample acquisition. 
However, there are some results that are valid and can be explained only by 
speculation at this time. ("Speculations" made here are mainly those of Christopher 
Schatte (1986).) The overall heart rate of the rats decreased slightly from preflight 
measurements, although it was steady. This probably comes from the reduced activity 
of the rats. A more important observation was the fact that body temperature rhythms 
disassociated from cardiac rhythms and began to free run. When these two rhythms 
disassociate, it can produce adverse effects, such as jet lag. Further experiments will 
be needed to test rhythm disassociation and determine its effects. 
Other areas where the rats showed changes possibly applicable to humans 
were muscles, bones, and growth hormone production. "Growth" hormone is involved 
in maintenance of muscles and bones, which showed deterioration. Flight animals 
produced less growth hormone than controls. This reduction could have caused the 
deterioration in muscles and bones. If this is true in humans, hormone therapy and 
exercise might counteract those effects. Loss of mass in muscles was evident, espe- 
cially in anti-gravity muscles. There were two groups of rats--mature rats and imma- 
ture, growing rats. The immature rats lost less muscle mass, but since they were sup- 
posed to be growing, there was a greater difference in weight between the flight and 
control immature rats than between the flight and control mature ones. Loss of mass 
tended to occur because of cell shrinkage rather than self-destruction. This could 
explain why no apparent long-term damage has been observed in humans. The main 
changes in bone were not in mass; they were increased fragility, reduced bone-plate 
growth activity, and shifting of bone mineral from lower to higher specific gravity frac- 
tions. Increased bone demineralization, usually considered an indicator of decreased 
bone integrity, did not occur in significant amounts. This integrity indicator may have to 
be reassessed, since an increase in bone fragility did occur. A decrease in a certain 
polypeptide (osteocalcin) might be responsible, since decreases correlated with min- 
eral loss. If it is, therapy might be possible. The little demineralization that did occur 
was found even in bones that did not play a significant anti-gravity role. This indicates 
137 
that a systemic factor might be involved. There is much to be learned from SL-3, if we 
can discover what the results mean. However, the results that we do understand are 
probably applicable to humans. 
Animals are indispensable to the space program. Their continued use could 
have many significant results. Those who are opposed to using animals in space 
should remember that space animals are treated humanely; they are necessary 
because results can be obtained from them that would be unobtainable from humans; 
and results from animal experiments can be applied to human systems. Therefore, 
NASA should continue to use animals in space research. 
BIBLIOGRAPHY 
I P. X. Callahan, et al., Ames Research Center Life Sciences Payload: Overview of 
Results of a Spaceflight of 24 Rats and 2 Monkeys. AIAA Paper 86-0583, AIAA 
24th Aerospace Sciences Meeting 1986, American Institute of Aeronautics and 
Astronautics, New York, 1986. 
C. Kelly Hill (Editor), Spacelab Mission 3 Experiment Descriptions, NASA TM-82502, 
Marshall Space Flight Center, Alabama, 1982. 
Management and Technical Services Company, Ames Research Center Spacelab 
Life Sciences- 1 Payload Integrated Experiment Requirements Document, Doc. 
No. ADE-82-50-002 Rev-1 , Moffett Field, CAI 1986. 
C. Schatte, R. Grindeland, P. Callahan, G. Funk, W. Lencki, and W. Berry, Animal 
I 
I 
Studies on Spacelab-3, NASA Technical Memorandum 8821 2, National Aero- 
nautics and Space Administration, Moffett Field, CAI 1986. 
I C. Schatte, Significance of the SL-3 Results, Unpublished (1 986). 
I 
I 
~ 
SLS-1 Rodent Experiments Science Working Group, Meeting Report (Untitled), Ames 
Research Center--Life Sciences Flight Experiments Projects Office, 1 986. 
. 
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Figure 1 .- The research animal holding facility (RAHF). 
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Figure 2.- Animal enclosure module. 
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Figure 3.- Frog embryology unit. 
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