Animal testing is a common practice in the experimental science field. Biologists test new drugs on mice, monkeys, and other mammals to identify their effects. Psychologists analyze the behavior of mice in groups and compare it to human behavior. Other experts utilize rabbits and other small mammals to assess the effects of business products on living organisms. Some scientists even test out the medical effects of marijuana on pets. Aside from these experimentations, animals have also contributed to space exploration which is one of mankind’s best achievements. Exploring outer space is a dangerous endeavor and scientists had to perform various tests to understand the conditions in it. Before humans went to space, scientists were cautious about various factors, such as the effects of microgravity and space radiation. Animal testing allowed scientists to better understand the conditions in space without the risk of human death.

The First Animal in Space

During the 1930s and 1940s, scientists conducted various experiments to understand outer space and prepare humans for space exploration. These experiments involved sending different types of animals to space which included dogs and monkeys. However, the first animal in space was not a mammal but an insect. American scientists sent fruit flies into space in 1947 aboard the United States V2 rocket (The History, n.d.). The scientists chose fruit flies as the best candidate for the test since they have a similarity to human genes. Fruit fly genetic codes have a 75% similarity with the disease-causing genes in humans (Mancini, n.d.). This allowed scientists to observe the changes that space may cause to specific genes.

Scientists conducted fruit fly experiments to assess the possible effects of microgravity and space radiation on living organisms. According to the Merriam-Webster Dictionary, microgravity is the weightless condition in outer space. Microgravity causes objects in space to move in various dimensions which were foreign to humans. Earlier scientists theorized that microgravity may cause lethal effects in humans after long-term exposure (Dorminey, 2019). When the American scientists successfully sent the fruit flies to space and retrieved them upon reentry to Earth, they discovered that microgravity and space radiation does not have an adverse effect on the creatures. The fruit flies returned to Earth in normal conditions which assured scientists that space radiation does not cause any mutation to genes. The discovery and success during the fruit fly experiment prompted scientists to perform more animal space experiments which eventually brought humans to space.

Monkeys in Space

Monkeys, chimpanzees, and gorillas are common animals that scientists use for animal testing and various research. These animals have a similar genetic code to humans as well as identical anatomy which makes them great candidates for scientific experiments. Due to this, scientists have sent 32 monkeys and apes to space (Forrester & Smalley, n.d.). The first monkey in space was a rhesus monkey named Albert who boarded a V2 rocket in 1948. Scientists followed this experiment with three more flights that involved monkeys which involved the monkeys named Albert II, Albert III, and Albert IV (The History, n.d.). The flights involved injecting anesthetics into the monkeys to keep them calm during the strenuous flights. While the monkeys successfully reached suborbital space, the four individual flights experienced mechanical failures that led to the death of the animals.

Aside from the four monkeys, the chimpanzees that went to space contributed to the mission of bringing humans to space. Ham, the first chimpanzee in space, boarded a rocket in January 1961 and successfully returned to Earth. The experiments regarding Ham included training in lever pulling and the use of space equipment (Gorman, 2021). The successful experiments revealed that living organisms can still move effectively in space and perform necessary tasks. With this knowledge, science stepped closer to successfully sending humans to space. Additionally, a chimp named Enos became the first chimpanzee to orbit the Earth and safely return. Enos’ successful orbit and return led to the successful orbital flight of American astronaut John Glenn. This showed the great contribution of animals in space exploration as they allowed humans to safely travel with less risk.

Dogs in Space

While American scientists utilized monkeys and chimpanzees, the Soviet Union preferred to use dogs in their space-related experiments. One of the earlier dogs in space was a mongrel named Laika. Laika boarded Sputnik 2 in November 1957 which the Soviets programmed to orbit the Earth. However, Laika died a few hours during the flight due to a thermal malfunction causing the dog to overheat (The History, n.d.). Despite the setback, the Soviets continued to train dogs for space exploration. In August 1960, they sent two mongrels named Belka and Strelka to orbit the Earth. The flight was successful and the two mongrels orbited the Earth 17 times before returning to the ground (Hollingham, 2017). While one of the dogs experienced vomiting during the orbit, both were in healthy condition upon their return to Earth. This successful flight further provided scientists with data on the effects of space on living organisms. Additionally, the two dogs became ambassadors between the United States and the Soviet Union. One of Strelka’s puppies became a resident of the White House and strengthened the diplomatic relationship between the two nations.

Other Animals that Visited Space

Monkeys and dogs became iconic animals that visited space. However, scientists have also sent amphibians, fishes, and reptiles to space. The experiments involving these animals focuses more on identifying the effects of outer space condition on living organisms than helping scientists develop methods to safely send humans into space. In 1970, NASA sent two bullfrogs to space to assess the effects of microgravity on vestibular systems. Frog ears have similarities with humans which makes them great candidates for the experiments. The various experiments revealed that microgravity caused changes in the frogs’ liver and vertebra while not affecting other organs (Yamashita et al., 1998). In microgravity, the frogs spread their limbs which were similar to their freefall pose. This pose is their reaction towards microgravity as they experience the sensation of freefalling. The frogs in space eventually adapted to microgravity after 8 days in orbit where they displayed natural behaviors. Once the frogs experienced normal gravity, they readapted after 12 hours. These studies showed that frogs can easily adapt to microgravity despite the minor effects it can pose to their organs.

As mentioned earlier, fruit flies were the first animal in space. Their similarity with human genes makes them effective subjects for space experiments. A recent study regarding fruit flies in space revealed that long-term exposure to microgravity causes cardiac issues to fruit flies (Walls et al., 2020). Space flight caused the fruit flies’ hearts to become smaller and contract. Microgravity also affected the chemicals present in the fruit flies’ hearts which had underlying effects on the animals. Additionally, according to Iwase et al. (2020), microgravity affects human neuro vestibular, cardiovascular, ocular, musculoskeletal, bone metabolic, immunological, and nervous systems. The results from fruit fly experiments as well as the data from astronauts show that long-term exposure to microgravity can cause serious health issues. Scientists must further investigate these theories in preparation for distant space travel and developing better living conditions in space. 

Spiders, fishes, tortoises, and worms have also made it to space. In 1968, the Russians sent tortoises, worms, soil, and seed to space via the Zond 5 Spaceship. The spaceship went around the moon and successfully returned to Earth. The tortoises on the ship experienced a ten percent weight loss. This could be due to microgravity’s effect or the diet that the animals had during the flight. Other space experiments involved observing fishes and spiders in space. The experiments showed that spiders spin finer webs while in space. The fishes that experienced microgravity swam in loops in an attempt to adjust to the weightlessness. The fishes eventually adapted to microgravity after a few days and showed normal behavior. Scientists also utilized medaka fish to assess the effects of space radiation on bone degradation and muscle wastage (Forrester & Smalley, n.d.). These experiments aim to further provide data regarding the effects of space on human anatomy, motor skills, and other physiological conditions.

Ethics of Animal Testing in Space Programs

While animal testing greatly contributed to space exploration progress, the ethics of the practice is a controversial topic. According to Lori Marino, an evolutionary neurobiologist, previous space experiments regarding animals were mostly one-way trips (as cited in Dorminey, 2019). The experiments regarding Laika and the Albert monkeys support this fact as most of them died due to mechanical failures. The spaceships that the monkeys boarded failed to launch their parachutes which caused the premature death of the animals. There was also the 1959 flight where the monkeys Able and Baker went to space and successfully returned to the ground. However, Able died due to an anesthetic reaction to an infected electrode (The History, n.d.). In Laika’s case, a thermal system malfunction led to the death of the dog. However, the Soviets initially claimed that Laika survived for a week with enough sustenance and died painlessly (Hollingham, 2017). Sputnik 2’s design, which was Laika’s spaceship, shows that the vehicle was irretrievable. This implied that Laika’s fight was a one-way trip and the scientists did not intend for the dog to return to earth. While most of these animal deaths are not deliberate, they show the high risk of space experiments. However, this high risk is the main reason for scientists to practice animal testing instead of experiencing human casualties during the early space flights.

The ethics of animal testing is an extensive argument that involves legal, social, and philosophical factors. While the early animal testing involved painful deaths for the creatures, it allowed the Soviets and the Americans to avoid losing human life (NASA, as cited in Dorminey, 2019). If scientists skipped animal testing and sent humans to space without prior experiments, the space programs would have experienced a high number of casualties and slowed the progress in space exploration. Despite this, individuals such as Marino argue that humans do not have the right to put animal lives at risk for the advancement of human progress and science (as cited in Dorminey, 2019). Still, the scientific community acknowledges the contributions of animals, especially dogs and monkeys, to space exploration.


The animals that went to space paved the way for astronauts to safely travel the atmosphere and survive the conditions in space. The initial experiment with fruit flies motivated scientists to continue sending animals to space to better understand the alien environment. These proceeding experiments involved the help of monkeys, dogs, chimpanzees, and other animals. The earlier experiments provided optimistic results with suboptimal outcomes that led to the death of many animal subjects. Early spaceships were prone to malfunctions while some are one-way vehicles that were irretrievable. These consequences led to arguments regarding the ethics of animal testing, however, scientists acknowledge the importance of animals in space programs and are continuously utilizing them to learn more about space. Animals like Laika, the Albert monkeys, Ham, Strelka, Belka, and Enos contributed their lives to the advancement of science and allowed humans to leave their mark in space.

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Reference List

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Gorman, A. (2021). Apes, Robots, and Men: The Life ad Death of the First Space Chimp. Available at Accessed October 27, 2021.

Hollingham, R. (2017). The Stray Dogs that Led the Space Race. BBC. Available at Accessed October 27, 2021.

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Yamashita, M., Izumi, A., Mogami, Y., & Okuno, M. (1998). The Frog in Space (FRIS) Experiment Onboard Space Station Mir: Final Report and Follow-on Studies. Available at Accessed October 27, 2021.