On 15 May 1960 an uncrewed prototype performed 64 orbits of the Earth, but the reentry maneuver failed. On 28 July 1960, two dogs by the names of Chaika and Lishichka were launched into space, but the mission was unsuccessful when an explosion killed the dogs. However, on 19 August, the Soviet Union became the first to successfully recover living creatures back to Earth. The dogs, Belka and Strelka were successfully launched into space on a Vostok spacecraft and they completed eighteen orbits. Following this, the Soviet Union sent a total of six dogs into space, two in pairs, and two paired with a dummy. Unfortunately, not all the missions were successful. After gaining approval from the government, a modified version of Korolev's R-7 was used to launch Yuri Alexeevich Gagarin into orbit on 12 April 1961, which was before the United States was able to put Alan Shepard into space. Korolev served as capsule coordinator, and was able to speak to Gagarin who was inside the capsule. The first human in space and Earth orbit returned to Earth via a parachute after ejecting at an altitude of . Gagarin was followed by additional Vostok flights, culminating with 81 orbits completed by Vostok 5 and the launch of Valentina Tereshkova as the first woman cosmonaut in space aboard Vostok 6.