The dogs were caught in Moscow’s alleyways, and soldiers and doctors selected strays that were no heavier than about 13 pounds and no taller than about 14 inches, the dimension of the rocket’s nosecone. Chernushka, shown here during a routine weight check, went up into orbit in September 1963 accompanied by a mannequin human. She made it back safely.

The dogs had to be trained to relieve themselves once inside their space suits. The suits had special receptacles, but convincing the animals to use them was difficult and only the dogs who took to it were selected. For orbital flights, all the dogs were female. There was no room in the cabin for a male dog to cock its leg, so females were better suited to space.

Before sending dogs into space, the Soviets sent them up for suborbital test flights. From the July 2 1957 issue of Komsomolskaya Pravda: “They made their way back to their Motherland, back down to Earth, by parachute, from out of the heavens beyond the clouds. ... Throughout this time, the dogs experienced all the effects of outer space.”

Laika, the most famous space dog, went up in November 1957. During training she showed a great capacity for endurance and tolerance. She died soon after launch, though, a fact not revealed until 2002. At the time, the Soviets kept her “alive” for seven days in orbit, and newspapers would report on her health. She became a national hero and her face was emblazoned on everything from cigarettes…

… to spinning tops. This Japanese toy shows her boldly astride a Sputnik. But reality was more harrowing. First, she spent three days in the capsule on the launchpad. During launch, her heart rate tripled and her breathing quadrupled. In zero gravity, everything went back to normal. But the capsule’s cooling fans were useless, and Laika basically baked to death.

Countries were still putting her on stamps as late as the 1980s. Top row: Polish stamp (1964), Beninian stamp (1977). Bottom row: Mongolian stamp (1982), DPR Korean stamp (1987).

Belka and Strelka, shown here with American pianist Van Cliburn who met them when he was in Moscow on tour, had a happier fate. They spent a day in orbit in 1960, after which they were recovered safely, the first cosmonauts to return to Earth. They became massive celebrities, and one of Strelka’s puppies (Strelka is the one with the eye patches) was sent to John F Kennedy as a diplomatic gift.

These two dogs appeared on a huge range of products and memorabilia as well, including postcards, buttons, and this ceramic flask. They received fan mail from around the world, which was answered by the scientists who took care of them. When they died, their bodies were stuffed. Today they are on display at the Memorial Museum of Cosmonautics in Moscow.