Model of the Vostok capsule with its upper stage
|Operator||Soviet space program|
|Mission duration||4 days, 23 hours, 7 minutes|
|Manufacturer||Experimental Design Bureau OKB-1|
|Launch mass||4,720 kilograms (10,410 lb)|
|Callsign||Ястреб (Yastreb - "Hawk")|
|Start of mission|
|Launch date||14 June 1963, 11:58:58UTC|
|Launch site||Baikonur 1/5|
|End of mission|
|Landing date||19 June 1963, 11:06UTC|
|Perigee altitude||162 kilometres (101 mi)|
|Apogee altitude||209 kilometres (130 mi)|
|Epoch||15 June 1963, 08:00:00 UTC|
Vostok 5 (Russian: Восток-5, Orient 5 or East 5) was a joint mission of the Soviet space program together with Vostok 6; as with the previous pair of Vostok 3 and Vostok 4 the two Vostok spacecraft came close to one another in orbit and established a radio link.
Several delays plagued the prelaunch preparations of Vostok 5, the biggest being concern over elevated solar flare activity. At this early phase, it was not well understood what effects this might have on the spacecraft and its passenger, so the planned launch date of 11 June was postponed a few days. On the 14th, Bykovsky was strapped into the capsule awaiting liftoff when further delays occurred. A gyroscope in the Blok E stage malfunctioned and needed to be replaced, but this would mean removing the propellants from the booster, taking it down from the pad back to the vehicle assembly building, and delaying the launch another several days. It was decided to take the calculated risk of simply doing the repair work on the fully fueled launch vehicle. A replacement gyroscope was quickly installed and liftoff took place at 2:59 PM Moscow time. One last minor problem popped up when a pad umbilical failed to disconnect, but as soon as the booster began lifting, it was yanked out. The launch proceeded without any difficulties, although the Blok E stage slightly underperformed and put the spacecraft into a lower-than-intended orbit at 108×137 miles (175×222 kilometers) versus the normal 112×146 miles (181×235 kilometers).
Cosmonaut Valery Bykovsky was originally intended to stay in orbit for eight days, but the mission details changed many times due to elevated levels of solar flare activity at the time and he was eventually ordered back after five days. This remains the record for solo crewed flight in Earth orbit. In addition, the low orbit of the spacecraft made it uncertain as to whether decay would not occur in under eight days. This combined with solar flare activity affecting the diameter of the Earth's atmosphere might potentially introduce drag that could not only cause premature reentry, but result in Vostok 5 landing almost anywhere on Earth.
Bykovsky performed a couple of simple scientific experiments in orbit and also practiced exercise and testing his body's reactions to weightlessness. In the postflight debriefing, he would say that the overall design of the spacecraft was good, but the clock was in a location that made it hard to see and the instrument panel was placed too far away. The first aid kit could not be reached at all without unstrapping from the seat. Like Valentina Tereshkova, he noted that the helmet headset produced sharp, unpleasant noise. He described the food as generally of good quality, although it probably should not be eaten before launch.
A problem with the spacecraft's waste collection system is reported to have made conditions "unpleasant" in the capsule. The only other difficulty encountered was that, like on Vostok 1 and Vostok 2, the re-entry module failed to separate cleanly from the service module when it was time for Bykovsky to come home and he experienced several seconds of sharp vibrations following separations.