Vanguard Six

At the Gromov Flight Research Institute, a spacecraft simulator had been built, called the TDK-1. Owing to the inefficiency of training all 20 cosmonauts in the simulator, it was decided they would select six men who would go through accelerated training.^[7] This group, which would be known as The Vanguard Six, was decided on May 30, 1960, and initially consisted of Gagarin, Kartashov, Nikolayev, Popovich, Titov, and Varlamov.^[7] Alexei Leonov recalls that these six were the shortest of the group of 20.^[8]

In July, shortly after relocation to Star City, two of the six were replaced on medical grounds. Firstly, during a centrifuge test of 8 g, Kartashov experienced some internal damage, causing minor hemorrhaging on his back.^[9] Despite Gagarin's requests for him to stay, the doctors decided to remove Kartashov from the group of six. Later in July, Varlamov was involved in a swimming accident. During a dive into a lake near the training center, he hit his head on the bottom, displacing a cervical vertebra.^[10] So by the end of July, the Vanguard Six were: Gagarin, Bykovskiy, Nelyubov, Nikolayev, Popovich, and Titov.^[7]

By January 1961, these six had all finished parachute and recovery training, as well as three-day regimes in simulators.^[11] On January 17, the six participated in their final exams, including time spent in a simulator, and a written test. Based on these results, a commission, supervised by Kamanin, recommended the use of the cosmonauts in the following order: Gagarin, Titov, Nelyubov, Nikolayev, Bykovskiy, Popovich.^[11] At this stage Gagarin was the clear favorite to be the first man in space, not only based on the exams, but also among an informal peer evaluation.^[12]

Korabl-Sputnik 1

The first Vostok spacecraft was a variant not designed to be recovered from orbit; the variant was also called Vostok 1KP (or 1P).^[15] At Korolev's suggestion, the media would call the spacecraft Korabl-Sputnik, ("Satellite-ship"); the name Vostok was still a secret codename at this point.^[15] This first Vostok spacecraft was successfully sent into orbit on May 15, 1960.^[15] Owing to a system malfunction, on the spacecraft's 64th orbit the thrusters fired and sent it into an even higher orbit. The orbit eventually decayed, and it re-entered the atmosphere several years later.^[16][17]

Vostok 1K

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.^[17] 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 other biological specimens such as mice, insects, and strips of human skin.^[18] This mission was successful, and Belka and Strelka became the first living beings recovered from orbit.^[18] The spacecraft was only the second object ever to have been recovered from orbit, the first being the return capsule of the American Discoverer 13 the previous week. During the mission there was some concern for Belka and Strelka's health, after images of Belka vomiting had been obtained from the onboard cameras.^[18] The spacecraft and dogs were recovered following the 26-hour spaceflight, and extensive physiological tests revealed that the dogs were in good health.^[19] This represented a significant success for the Vostok programme.^[19]

The success of Korabl-Sputnik 2 gave the designers confidence to put forward a plan leading to a human spaceflight. A document regarding a plan for the Vostok programme, dated September 10, 1960, and declassified in 1991, was sent to the Central Committee of the Communist Party, and approved by Premier Nikita Khrushchev.^[19] This document had been signed by the top leaders in the Soviet defence industry at the time, the most senior being Deputy Chairman Dmitriy Ustinov; this indicated the elevated importance of the document.^[19] The plan called for one or two more Vostok 1K flights, followed by two uncrewed Vostok 3K flights, followed by a crewed flight in December 1960.^[20]

A major setback occurred on October 24, when a rocket explosion killed over 100 people, including Chief Marshal of Artillery Mitrofan Nedelin, in what is now called the Nedelin catastrophe. This was one of the worst disasters in the history of spaceflight. It involved a rocket that was not designed by Korolev, and was not necessary for the Vostok programme; the rocket was by rival designer Mikhail Yangel, intended to be a new generation of intercontinental ballistic missiles.^[21] It would be two weeks before work on the Vostok programme continued, and it was realised that the original target of a December crewed launch was unrealistic.^[21]

On December 1, 1960, the next Vostok 1K spacecraft, called Korabl-Sputnik 3 by the press, was launched. It carried the two dogs Pchyolka and Mushka. After about 24 hours, the engines were intended to fire to begin re-entry, but they fired for less time than had been expected. This meant that the spacecraft would enter the atmosphere, but not over Soviet territory. For this reason the self-destruct system was activated, and the spacecraft and the two dogs were destroyed.^[22] At the time, the press reported that an incorrect altitude caused the cabin to be destroyed upon re-entry.^[22]

The next Vostok 1K spacecraft was launched on December 22, 1960, but it was unnamed because it failed to reach orbit. It carried two dogs, named Kometa and Shutka. The third stage of the launch system malfunctioned, and the emergency escape system was activated. The spacecraft landed 3,500 kilometres downrange of the launch site. The resulting rescue operation took several days, in -40 °C conditions. After a few days, the dogs were both recovered alive, and the spacecraft was returned to Moscow a few weeks later.^[23] Despite Korolev's desire to announce this failure to the press, the State Commission vetoed the idea.

Vostok 3KA

The two uncrewed missions immediately preceding the first human flight used the same spacecraft design as in the crewed missions, a design called Vostok 3KA (or 3A). The only differences were that they would carry a single dog into orbit, a life-size mannequin would be strapped into the main ejection seat, and (unlike the crewed missions) they had a self-destruct system.^[24] The recent failures of Vostok 1K were not encouraging, but it was decided to proceed with launches of an automated variant of Vostok 3KA, the spacecraft design that would conduct a human spaceflight. The approval of a crewed mission was contingent upon the success of the two automated Vostok 3KA missions.^[25] Unlike the previous Vostok 1K flights, the two uncrewed Vostok 3KA flights were planned to last only a single orbit, to imitate the plan for the first human flight.

The first of these uncrewed flights, Korabl-Sputnik 4, was launched on March 9, 1961. It carried the dog Chernushka into orbit, as well as a mannequin called Ivan Ivanovich, who wore a functioning SK-1 spacesuit.^[26] The dog was contained in a small pressurized sphere, which also contained 80 mice, several guinea pigs, and other biological specimens.^[26] Additional mice, guinea pigs, and other specimens were placed within the mannequin.^[26] After one orbit, the descent module successfully re-entered the atmosphere, the mannequin was safely ejected, and the dog and other specimens landed separately in the descent module by parachute.^[27] The spaceflight lasted 106 minutes, and the dog was recovered alive after landing. The mission was a complete success.^[27]

On March 23, before the next mission, an accident occurred during training which led to the death of cosmonaut candidate Valentin Bondarenko. He was burned in a fire in an oxygen-rich isolation chamber, and died in a hospital eight hours after the incident.^[27] Bondarenko's death was the first known cosmonaut or astronaut fatality. It is not clear whether other cosmonauts were told of his death immediately;^[27] the media did not learn of Bondarenko's death – or even of his existence – until many years later, in 1986.^[28] Unsubstantiated reports of other cosmonaut deaths created the myth of the lost cosmonaut.

The next uncrewed flight, Korabl-Sputnik 5, was launched on March 25, two days after Bondarenko's death. Like the previous Vostok 3KA flight, it lasted for only a single orbit, carried a mannequin and a dog, Zvezdochka ("Starlet",^[30] or "Little star"^[31]). This mission was also a complete success, which was the final step required to get approval for a crewed mission. The re-entry module of the Korabl-Sputnik 5 spacecraft, also called Vostok 3KA-2, was auctioned at Sotheby's on April 12, 2011, the 50th anniversary of the first human spaceflight, Vostok 1. Evgeny Yurchenko, a Russian investment banker, paid $2,882,500 for the capsule.^[32]

Crewed flights

Cancelled missions

One different (1963) and seven original (going through to April 1966) Vostok flights were originally planned:

• Vostok 6A - pair to Vostok 5 group flight with female cosmonaut instead fulfilled Vostok 6 flight
• Vostok 7 - 8-days high-altitude flight for radiological-biological studies with natural re-entry from orbit
• Vostok 8 - pair to Vostok 9 10-days group high-altitude flight for extended scientific studies with natural re-entry from orbit
• Vostok 9 - pair to Vostok 8 10-days group high-altitude flight for extended scientific studies with natural re-entry from orbit
• Vostok 10 - 10-days high-altitude flight for extended scientific studies with natural re-entry from orbit
• Vostok 11 - supplemental flight for extra-vehicular activity tests
• Vostok 12 - supplemental flight for extra-vehicular activity tests
• Vostok 13 - 10-days high-altitude flight for extended scientific studies with natural re-entry from orbit

All these original missions were cancelled in early 1964 and the components recycled into the Voskhod programme, which was intended to achieve more Soviet firsts in space.