For better or worse, humans have sent an ark’s worth of other animals into space. This veritable zoo of space travelers includes dogs, mice, fish, tortoises, frogs, spiders and non-human primates.

But let’s start with some little guys — fruit flies. 

First Animals in Space: Fruit Flies

Fruit flies were the first animals of any kind to leave the planet. Fruit flies make good experimental subjects because they’re remarkably similar to humans at the genetic and cellular levels. 

They’d been a darling of the research world for years, so they were an obvious choice for conducting biomedical research in space. However, the biggest advantage of fruit flies for off-planet research is that they don’t take up much room on an already small spaceship. 

Primates in Space

Fruit flies may be suitable for biomedical research, but mammals were needed when it came to testing the physiological effects of spaceflight on humans. The first mammal sent into space was a rhesus monkey named Albert II. 

The US Air Force launched Albert II in 1949 after his predecessor, Albert I, was launched in 1948. Unfortunately, Albert I died before reaching space, and sadly, Albert II didn’t survive his mission, either — though he did make it to space and into the record books. He died after his capsule’s parachute failed to open on reentry. Albert III, IV, V and VI (also known as Yorick) suffered similar fates. 

In 1958, a squirrel monkey named Gordo was launched into space on a Jupiter rocket. Gordo died on splashdown when a flotation mechanism failed. Rhesus monkeys Sam and Miss Sam (Sam’s mate) fared better. Both survived their missions to be returned to the training colony.

The early days of spaceflight were hard on monkeys. Arguably it was no easier for chimpanzees, but at least more of them survived the ordeal. In January 1961, a chimpanzee named Ham became the first chimp in space. His suborbital flight path was similar to the one Alan Shepard would soon take. Later that year, Enos, the first chimp to orbit Earth, returned from his flight in good condition. The successful missions of primates in space paved the way for human spaceflight.

Read More: A Brief History of Chimps in Space 

Russian Dog in Space

While the US was sending monkeys into space, the Soviet Union preferred to send dogs. The most famous canine space traveler was Laika, though she was not the first dog in space. Dezik and Tsygan, two dogs launched by the Soviets in 1951, have that honor. Between 1951 and 1952, Soviet rockets ferried nine dogs into space. Two dogs named Strelka and Belka, along with 40 mice, were aboard the 1960 launch of Sputnik 5. 

Laika, however, was the first animal of any kind to orbit the Earth. Laika didn’t survive her journey, though this was not a surprise. At the time, there was no way to bring her back. It was expected that she would run out of oxygen after about ten days, but according to NASA’s recounting, she likely died after a day or two due to “thermal problems” when a fan on the craft failed. 

First Cat in Space

For reasons you might be able to guess if you share your home with a cat, felines were not often used in space programs. However, a dainty French cat named Félicette spent 15 minutes in space in 1963. The five-pound, black and white cat made it safely back to Earth. She was euthanized soon after her return so scientists could study how spaceflight had affected her body. France never sent another cat into space (nor did any other space program).

Read More: Details on Space Aging Informs Health Research

Other Animals Sent to Space

Once it was clear humans could survive the rigors of space travel, animals were used less as test-flight dummies. Instead, they were pressed into service in space labs as subjects in various scientific experiments. Plenty of mice, frogs, spiders, fish, and even tiny tardigrades (not to mention bacteria) have spent time off the planet.              

On its website, NASA states:

“[T]hese animals have taught the scientists a tremendous amount more than could have been learned without them. Without animal testing in the early days of the human space program, the Soviet and American programs could have suffered great losses of human life. These animals performed a service to their respective countries that no human could or would have performed. They gave their lives and/or their service in the name of technological advancement, paving the way for humanity’s many forays into space.”

No doubt, these space programs have provided tremendous benefits to both humans and other animals, but these animals didn’t volunteer. Still, we could not have done it without them; they deserve to be remembered.