Laika became the first animal to orbit Earth when she flew aboard the Soviet spacecraft Sputnik 2.
Laika was a stray dog selected from Moscow and launched on November 3, 1957, less than a month after Sputnik 1. Sputnik 2 was designed and built rapidly, so it had no system for returning its passenger safely to Earth. The mission therefore provided data about how a living creature might tolerate launch and weightlessness, but Laika died several hours after reaching orbit because of overheating and stress.
Her flight was a major milestone in space biology and attracted worldwide attention. The mission proved that an animal could survive launch and enter orbit, though it also became an enduring example in debates about the ethics of animal experimentation.
Laika is often confused with Belka and Strelka, who later became the first dogs to orbit Earth and return alive. The American chimpanzee Ham also flew in space, but he did not orbit Earth.