Why Soviets Sent Dogs to Space While Americans Used Primates

The cosmonaut ran away a day before his flight. The training had been grueling and confusing. The food was bad. The cosmonaut hadn’t signed up for this at all.

It couldn’t have: It was a dog.

The researchers at the Institute of Aviation Medicine in Moscow rushed to find a replacement. They plucked a stray dog off the street and named it ZIB, a Russian acronym that means “substitute for missing Bobik,” a common name for a small dog. The mutt was placed inside a capsule, strapped to a rocket, and blasted to the edge of space. It returned in one piece.

This historic flight happened in September 1951. The Soviet Union was developing a program to launch men into orbit, and dogs were their test subjects. On the other side of the world, the United States was carrying out similar biomedical research, only with primates, including monkeys and chimpanzees.

Human beings had lived for all of history beneath the cosmic tarp we call an atmosphere, safe from the universe. No one knew how our bodies would react to weightlessness. Some physicians thought basic functions, like swallowing and pumping blood to the heart, would be impossible without the steady tug of gravity.

“We take for granted now that animals and humans can function in space, but back then we knew absolutely nothing,” says Bill Britz, an American veterinarian who worked with the chimpanzees who flew to space in the early 1960s.

The goal for the Cold War rivals was the same: to prove that animals could survive in orbit so that people could, too. But why did the Soviets use dogs, while the Americans used primates?

The story of ZIB illustrates one rather pragmatic reason: Dogs were everywhere. The Moscow streets were crowded with stray dogs—free, if unwilling, volunteers.

The Soviet Union already had a long tradition of using dogs as research participants, says Amy Nelson, a history professor at Virginia Tech who has studied the Soviet space dogs. At the turn of the century Ivan Pavlov’s work with canines uncovered the learning process known as classical conditioning, a reflexive behavior that ties together a stimulus and a response. Pavlov had been studying canine digestion when he noticed that his pup subjects drooled before he even gave them meat, a hint that something had tipped them off that a delicious treat was coming.

Primates were more difficult to acquire. The chimpanzees were brought over from the Congo region in Africa, Britz says. The Air Force, which conducted some of the earliest primate flights before NASA was established in 1958, paid catchers in African nations to collect dozens of young chimps. Many of the test subjects arrived at the headquarters of the program, Holloman Air Force Base in New Mexico, in poor shape. Out of nine veterinarians, eight contracted hepatitis from the chimps. Britz was the only one who didn’t get sick.

The chimps were one to two years old. “They were just like kids,” Britz says. “We would play with them.” He remembers getting a call at home about flickering lights inside one of Holloman’s buildings. When he arrived, he found that one chimp had opened a padlock, escaped his cage, and helped another chimp out of his own. They were running around the lab, flipping light switches, and pulling chemical wipes from their container, one by one, as if they were Kleenex tissues.

American researchers picked primates because of their physiological similarities to humans, according to veterinarians and historians. They wanted chimps for their intelligence, too. The researchers taught the chimpanzees to conduct simple tasks during flight to test another important unknown—whether it was possible to remain conscious and actually do something in weightlessness. The chimps were taught to push levers in a certain sequence, prompted by flashing lights. If they got it wrong in training, they received a mild electric shock to their feet. For correct moves, they were rewarded with banana pellets. During the short flights, the chimps touched the levers from launch to reentry.

Nelson says that the Soviets did consider using primates, particularly monkeys. They visited the circus and asked monkey handlers how the animals might fare in a rocket launch. “And they’re like, ‘No, they’re way too high-strung, they’re temperamental, they’ll succumb to the stress of the experiment,’” Nelson says.

In both countries, the training for the animals was intense, according to Animals in Space, a comprehensive history by Colin Burgess and Chris Dubbs, and might be labeled animal abuse today. The Soviet dogs were restrained in small containers for hours to simulate the confinement of spaceflight. They were exposed to loud banging noises and spun around in centrifuges to mimic the extremes of spaceflight, from launch to landing. On the American side, primates were subjected to similar shakes and sounds, on top of their motor-skills training.

The Americans began their test flights in 1948 with rhesus macaques. The first six died of suffocation, explosions in flight, or upon impact. Britz says the chimpanzees who flew in the early 1960s fared better. He remembers seeing Ham, the first chimp in space, after he was recovered from a successful flight to the boundary where space begins. “He was in such mint condition,” Britz said of Ham, who went on to live in zoos until his death in 1983. Enos, the second and last chimp to fly, survived the journey but died several months later of a bacterial infection that Britz said was unrelated to spaceflight.

The memory of the Soviet space dogs lives on today in a menagerie of merchandise, from T-shirts to nesting dolls, a legacy that glosses over a less charming reality. Laika, the first dog to go beyond the edge of space and complete an orbit of Earth, breathed frantically during launch, her heart racing at triple the normal speed. The Soviets didn’t design the mission for a safe return, and Laika died in space not long after launch, from the excessive heat in the capsule, in 1958.

“The Russians felt very badly about it, especially about Laika,” says Cathy Lewis, a curator in the space-history department at the Smithsonian National Air and Space Museum. “The principal investigator, Oleg Gazenko, who sent Laika up into space, and knowing full well that she was not going to return—before he died, [he said] that was the one thing in his career that he had really regretted.” Before the flight, Gazenko had brought Laika home with him to play with his children, Lewis says.

Researchers switched to the animals that were becoming the preferred subject in laboratory study: rodents. These smaller creatures would help answer more complex questions about spaceflight, like how space radiation affects health. “If something changes in one animal, you don’t know if it’s truly representative of the science, but if it changes in 30 mice, you’ve got a pretty good cause and effect,” says Richard Simmonds, a veterinarian who worked at NASA in the early 1970s and oversaw the handful of mice that went to the moon on Apollo 17. “By the time I got there, it was pretty well-determined that flying the animals just to prove the safety of the flight had been done.”

Today, nearly 70 years after that Soviet dog bolted and lived out a life firmly on the ground, scientists continue to send animals into space as research proxies for people. According to NASA, there are some mice on the International Space Station right now, circling the Earth along with the astronauts on board.