The first animals to reach space were fruit flies that the United States launched aboard captured German rockets in 1947. The first mammal to reach space was a rhesus monkey named Albert II, who flew two years later.
Both these missions were suborbital, as were all animal flights for about a decade. The first animal to orbit Earth was Laika, a dog launched by the Soviet Union in 1957 who died in orbit. The first animals to orbit Earth and land safely were the host of animals on the Soviet Sputnik 5 mission in 1960, led by dogs Strelka and Belka.
In these early days of rocket science, no one knew what spaceflight was like. Engineers flew animals, particularly dogs, monkeys and chimps, to learn how to launch and land living beings safely and to better understand how spaceflight might affect human bodies.
Since then, animals continue to play an important role in understanding the impact of microgravity on many biological functions. Astronauts have studied all kinds of animals — wasps, beetles, tortoises, flies, worms, fish, spiders, rabbits, bees, ants, frogs, mice, crickets, rats, minnows, newts, snails, urchins, moths, brine shrimp, jellyfish, guinea pigs, butterflies, scorpions and cockroaches, among many others.
Photos: Pioneering animals in space
Animal astronaut firsts
Although there is no distinct boundary between the atmosphere and space, an imaginary line about 68 miles (110 kilometers) from the surface, called the Karman line, is usually where scientists say Earth's atmosphere meets outer space.
The first animals to reach space — not counting any bacteria that may have hitched a ride on previous rockets — were fruit flies. On Feb. 20, 1947, the United States put fruit flies aboard captured German V-2 rockets to study radiation exposure at high altitudes. In 3 minutes and 10 seconds of flight, the fruit flies reached an altitude of 68 miles.
The first mammal in space was Albert II, a rhesus monkey launched by NASA who reached an altitude of 83 miles (134 km) on June 14, 1949. Albert was anesthetized during flight and implanted with sensors to measure his vital signs but died upon impact at re-entry.
While the United States chose monkeys to stand in for humans on the earliest flights, the Soviet Union used dogs instead. The first dogs launched, Tsygan and Dezik, were aboard the R-1 IIIA-1. The dogs reached space on July 22, 1951, but did not orbit. They were the first mammals successfully recovered from spaceflight.
The first animal to orbit Earth was Laika, another Soviet dog who launched in 1957. American reporters dubbed her "Muttnik" as a pun on Sputnik, which the Soviet Union had launched about a month prior and which became the first satellite to reach orbit. Laika died in orbit as a re-entry strategy could not be worked out in time for the launch.
The first mammals to orbit Earth and survive were a host of animals that the Soviet Union launched on a mission called Sputnik 5 on Aug. 19, 1960. The most famous crewmembers on this flight were two other Soviet space dogs, Belka and Strelka, but the flight also carried "a gray rabbit, 40 mice, 2 rats, and 15 flasks of fruit flies and plants," according to NASA (opens in new tab).
In 1968, two steppe tortoises became the first animals to fly around the moon as part of the Soviet Zond 5 mission, which was the first successful mission around the moon, according to NASA (opens in new tab). The Zond 5 tortoises survived the trip, but were dissected after their return to Earth so that scientists could compare them with grounded counterparts for any impact of spaceflight. (None of the eight tortoises involved in the experiment were allowed to eat beginning 12 days before launch, and apparently "the main structural changes in the tortoises were caused by starvation," according to NASA.)
Other famous animals in space
In the early decades of spaceflight, many animals reached space — and fame — even after the notable "firsts" were all claimed.
Gordo, a squirrel monkey, launched 600 miles high on Dec. 13, 1958. He died on splashdown when a flotation device failed.
Able, a Rhesus monkey, and Baker, a squirrel monkey, were launched together on May 28, 1959. Able and Baker flew 300 miles high and returned unharmed. However, Able died during an operation to remove an electrode from under her skin. Baker lived until 1984, dying of kidney failure at age 27.
Ham was a chimpanzee trained to perform tasks during spaceflight. Ham, named after the Holloman Aerospace Medical Center, became a celebrity after his flight on Jan. 31, 1961. Ham learned to pull levers to receive banana pellets and avoid electric shocks. He successfully became the first animal to actually interact with a space vessel rather than simply ride in it.
On Oct. 18, 1963, French scientists launched the first cat into space; Félicette survived her flight and was successfully retrieved after a parachute descent.
Two Russian dogs, Veterok and Ugolyok were launched into space on Feb. 22, 1966. They orbited for a record-breaking 22 days; humans did not surpass that record until 1974.
Living nematodes were found in the wreckage of the space shuttle Columbia three months after the spacecraft broke up while re-entering Earth's atmosphere, according to NASA (opens in new tab).
Animals in space research
Although the early animal astronauts achieved great fame, many other animals have quietly contributed to the body of scientific knowledge about life in space. As humans have grown more accustomed to space travel, fewer animals make the front-page news.
Still, their contributions are important. Nearly all of their flights have been designed to study the effects of microgravity on the biological functions of creatures from Earth.
Some of the biological functions that have been studied are (to name just a few): brain states, behavioral performance, cardiovascular status, fluid and electrolyte balance, metabolic state, tissue development, and mating in zero gravity.
Here are some examples of specific experiments:
Nov. 9, 1970: Two bullfrogs were launched on a one-way mission to learn more about space motion sickness.
July 28, 1973: Two garden spiders named Arabella and Anita (opens in new tab) were used to study how orbiting earth would impact spiders' ability to spin webs. Arabella spun a fairly symmetric web even though the thread thickness varied — something that earthbound spiders don't experience.
July 10, 1985: Ten newts flew on the Soviet-launched Bion 7 (opens in new tab) satellite. Their front limbs were amputated in order to study regeneration in space to better understand how humans might recover from space injuries.
April 17, 1998: More than 2,000 creatures joined in 16 days of neurological testing alongside the seven-member human crew of the shuttle Columbia.
Animals on the International Space Station
Animals continue to be studied in space today, particularly on the International Space Station. Some examples of space station experiments include:
2014: A student experiment sent a colony of ants to the ISS and compared them to other colonies on Earth. The aim was to see how microgravity affects the movements of the space ants as they search for food.
2016: Twelve male mice were sent to the orbiting complex for 30 days so that researchers could look at changes in the animals' DNA.
2017: Healthy mouse babies arose from mice sperm hosted on the ISS for nearly 300 days in 2013-14, suggesting that sperm for other species could be hosted off-Earth in case of catastrophe.
2021: A SpaceX cargo capsule carried research equipment including bobtail squid to the International Space Station in June 2021. On Earth, these animals host microbes that allow the squid to glow in the dark, according to NASA (opens in new tab), making baby squid a helpful model for studying how the microbiome endures conditions in space. The human microbiome is vital for processes like digesting food, and researchers want to understand how these partnerships are affected by spaceflight.
Additional resources and reading
Read an interview with author Stephen Walker about the role animals played in early spaceflight. A TIME photo feature (opens in new tab) highlights several of the early animals in space, and a feature in The Atlantic (opens in new tab) digs into why Soviets focused on dogs and Americans on monkeys.
- Gray, T. "A Brief History of Animals in Space," NASA, 1998. https://history.nasa.gov/animals.html (opens in new tab)
- Mains, R., et al. "A Researcher's Guide to International Space Station Rodent Research," NASA, 2015. https://www.nasa.gov/sites/default/files/atoms/files/np-2015-03-016-jsc_rodent-iss-mini-book-508.pdf (opens in new tab)
- NASA, "Project Mercury Ballistic and Orbital Chimpanzee Flights (CHIMP)," https://lsda.jsc.nasa.gov/Experiment/exper/907 (opens in new tab)
- NASA, "Skylab 3: Return to Skylab," July 25, 2018. https://www.nasa.gov/feature/skylab-3-return-to-skylab (opens in new tab)
- NASA, "Zond 5," Feb. 25, 2019. https://solarsystem.nasa.gov/missions/zond-5/in-depth/ (opens in new tab)
- NASA Space Science Data Coordinated Archive, "Bion 7," https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1985-059A (opens in new tab)
- Ibid., "Cosmos 110," https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1966-015A (opens in new tab)
- Uri, J. "60 Years Ago: Soviets Select Their First Cosmonauts," NASA, Feb. 25, 2020. https://www.nasa.gov/feature/60-years-ago-soviets-select-their-first-cosmonauts (opens in new tab)