Laika was a Soviet space dog who was one of the first animals in space and the first to orbit the Earth. A stray mongrel from the streets of Moscow, she flew aboard the Sputnik 2 spacecraft, launched into low orbit on 3 November 1957. As the technology to de-orbit had not yet been developed, Laika's survival was never expected. She died of overheating hours into the flight, on the craft's fourth orbit.

During the 1950s and 1960s the Soviet space program used dogs for sub-orbital and orbital space flights to determine whether human spaceflight was feasible. These dogs, including Laika, the first animal to orbit Earth, were surgically modified to provide the necessary information for human survival in space. The Soviet space program typically used female dogs due to their anatomical compatibility with the spacesuit. Similarly, they used mix-breed dogs due to their apparent hardiness.