Vostok programme it into an even higher orbit. The orbit eventually decayed, and it re-entered the atmosphere several years later. The next six launches were all of the "Vostok 1K" design, equipped with life-support facilities, and planned to be recovered after orbit. The first spacecraft launched on July 28, 1960 carried two space dogs named Chayka and Lisichka. An explosion destroyed the spacecraft shortly after launch, killing both dogs, and the mission was not given a name. The next mission, designated Korabl-Sputnik 2, was launched on August 19, 1960, carrying two more dogs, Belka and Strelka, as well as a variety of
Soviet space dogs the preferred animal for the experiments because scientists felt dogs were well suited to endure long periods of inactivity. As part of their training, they were confined in small boxes for 15–20 days at a time. Stray dogs, rather than animals accustomed to living in a house, were chosen because the scientists felt they would be able to tolerate the rigorous and extreme stresses of space flight better than other dogs. Female dogs were used because of their temperament and because the suit the dogs wore in order to collect urine and feces was equipped with a special device, designed