Laika (from the Russian: Лайка, a breed of dog, literally meaning "Barker" or "Howler") was a Soviet space dog (c. 1954–November 3, 1957) who became the first living mammal to orbit the Earth and the first orbital casualty. Little was known about the impact of space flight on living things at the time Laika's mission was launched. Some scientists believed humans would be unable to survive the launch or the conditions of outer space, so engineers viewed flights by non-human animals as a necessary precursor to human missions. The United States used chimpanzees; the Soviet program elected to use dogs. Laika, a stray, originally named Kudryavka (Russian: кудрявка Little Curly-Haired One), underwent training with two other dogs, and was eventually chosen as the occupant of the Soviet spacecraft Sputnik 2 that was launched into outer space on November 3, 1957.
Laika died a few hours after launch, presumably from stress and overheating, probably due to a malfunction in the thermal control system. The true cause and time of her death was not made public until 2002; instead, it was widely reported that she lived for several days. However, the experiment proved that a living passenger could survive being launched into orbit and endure weightlessness. It paved the way for human spaceflight and provided scientists with some of the first data on how living organisms react to spaceflight environments. On April 11, 2008, Russian officials unveiled a monument to Laika. A small monument in her honour was built near the military research facility in Moscow which prepared Laika's flight to space. It features a dog standing on top of a rocket.