Sergey Korolev, founder of the Soviet space program, in July 1954 with a dog that just returned to Earth after a lob to an altitude of 100 kilometers on an R-1D scientific rocket. In 1951, the Soviet Union became the first country to safely recover a living organism after a flight in space. In 1957, a dog, Layka, became the first living organism to reach Earth's orbit. Traveling aboard Sputnik 2, rising temperatures due to thermal control problems killed Layka on the fourth day of the mission.