||This article contains orbital elements but does not include an epoch, or date when those elements, which typically vary over time, were correct.|
|Harvard designation||1962 Alpha Mu 1|
|Mission duration||3 days, 22 hours, 28 minutes|
|Launch mass||4,722 kilograms (10,410 lb)|
|Callsign||Сокол (Sokol - "Falcon")|
|Start of mission|
|Launch date||August 11, 1962, 08:24UTC|
|Launch site||Baikonur 1/5|
|End of mission|
|Landing date||August 15, 1962, 06:52UTC|
|Perigee||166 kilometres (103 mi)|
|Apogee||218 kilometres (135 mi)|
Vostok 3 (Russian: Восток-3, Orient 3 or East 3) was a spaceflight of the Soviet space program intended to determine the ability of the human body to function in conditions of weightlessness and test the endurance of the Vostok 3KA spacecraft over longer flights. Cosmonaut Andriyan Nikolayev orbited the Earth 64 times over nearly four days in space, August 11–15, 1962, a feat which would not be matched by NASA until the Gemini program (1965–1966).
Vostok 3 and Vostok 4 were launched a day apart on trajectories that brought the spacecraft within approximately 6.5 km (4.0 mi) of one another. The cosmonauts aboard the two capsules also communicated with each other via radio, the first ship-to-ship communications in space. These missions marked the first time that more than one manned spacecraft was in orbit at the same time, giving Soviet mission controllers the opportunity to learn to manage this scenario.
- Mass: 4,722 kg (10,410 lb)
- Perigee: 166 km (103 mi)
- Apogee: 218 km (135 mi)
- Inclination: 65.0°
- Period: 88.5 minutes
Gherman Titov had suffered space sickness during his record-breaking one-day mission aboard Vostok 2. This condition was unknown at the time, leading Soviet scientists to devote efforts to study the effect of spaceflight on the human body.
In 1961, Soviet rocket engineer Sergei Korolev pushed for a three-day spaceflight as a follow-up to Vostok 2. Such a mission was opposed by the head of cosmonaut training Nikolai Kamanin and the cosmonauts themselves, who were concerned about unforeseen health effects that might result from extending space flights too quickly. Plans for a three-day mission only went forward when the approval of Soviet Premier Nikita Khrushchev was obtained; in the end, Vostok 3 would last nearly four days.
One objective of the missions of Vostok 3 and Vostok 4 was the study of how the reactions of Nikolayev and Pavel Popovich might differ during a series of tests under similar circumstances. The close orbits and near-rendezvous of the two spacecraft would keep the number of variables to a minimum, allowing the measurement of individual differences in adaptation to spaceflight. The Vostok spacecraft were upgraded to increase the volume of information collected about the flight conditions and the crew.
Training was expanded to condition cosmonauts against space sickness and select those candidate spacefarers deemed least susceptible. Informed by Titov's experience in Vostok 2, Nikolayev and Popovich thoroughly rehearsed their spacecraft maneuvers and other planned activities in a simulator.
The Vostok 3/4 flights were delayed by more than a month due to an accident in June when an attempted launch of a Zenit photo reconnaissance satellite failed and resulted in extensive damage to LC-1. Soviet officials claimed that manned spaceflights were impossible for a time due to a high-altitude nuclear test by the United States—probably Starfish Prime.
Vostok 3 lifted off from Gagarin's Start at Baikonur Cosmodrome at on August 11, 1962 at 08:24 UTC atop a Vostok 8K72K rocket. During his first day in orbit, Nikolayev unstrapped himself from his seat and became the first spacefarer to float freely in conditions of microgravity in space.
Nikolayev's orbital companion Popovich was launched the next day aboard Vostok 4. Data on the two spacecraft's orbital parameters that were released periodically by Soviet news agency TASS seemed to indicate a change in Vostok 3's orbital trajectory within ten hours of Vostok 4's launch, leading to speculation that the former spacecraft modified its orbit to bring it closer to that of the latter. The Vostok spacecraft is not believed to have had the ability to modify its orbit. Plans were for the spacecraft to approach to 5 km (3.1 mi), but the closest distance achieved was 6.5 km (4.0 mi). At the start of Vostok 3's thirty-third orbit this distance had diverged to 850 km (530 mi), and to 2,850 km (1,770 mi) at the start of the sixty-fourth.
Nikolayev and Popovich made contact with one another via shortwave radio soon after their spacecraft approached one another; they would maintain regular ship-to-ship communications over the course of their mission in addition to their contact with the ground. Nikolayev reported sighting the Vostok 4 capsule after it entered orbit near him.
Both Nikolayev and Popovich spent time out of their seats each day, conducting a series of tests to determine their ability to maneuver and work in conditions of weightlessness. Each test was said to last "about one hour." The physical and mental state of the cosmonauts were monitored: biometric sensors relayed the cosmonauts vital statistics to the ground; the cosmonauts' behavior and coordination was observed via a cabin-mounted video camera; and the cosmonauts' ability to perform various operations in coordination with ground controllers was considered. The cosmonauts' speech was monitored both by controllers on the ground and one another. The results of the tests were deemed positive, evidence of the ability of humans to function and work over longer periods in microgravity.
Attention was paid to the cosmonauts' ability to sleep, and their vital signs were monitored during their sleep periods. Nikolayev reported that he slept well, but always woke after only six hours of his scheduled eight-hour sleep period, feeling "refreshed".
Nikolayev fired his retrorocket pack and returned to Earth on August 15, 1962, landing at 06:52 UTC at , near Karaganda. As with Titov on Vostok 2—but unlike Gagarin on Vostok 1—Nikolayev would admit to reporters that he ejected and parachuted to earth separately from his spacecraft.
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