II.

Spacecraft

The Voskhod spacecraft outwardly resembled the earlier Vostok spacecraft, but it required many changes in order to support spacewalks and flights by more than one cosmonaut. Voskhod climbed into space on a modified Vostok rocket. Fitting more than one cosmonaut into the spacecraft’s small space meant leaving off the Vostok ejection system, so the cosmonauts could not escape if the rocket had trouble on the launch pad, as early rockets often did. In fact, they could not escape until the rocket climbed above most of the atmosphere and ejected the streamlined shroud covering the capsule. Then they could blast free using the capsule’s primary retrorocket. The haste of construction and the parts removed in order to fit another person into the capsule made Voskhod into the riskiest piloted spacecraft ever flown.

Like Vostok, Voskhod had two basic parts—a capsule and an equipment module that together weighed about 5300 kg (about 11,700 lb). The capsule was a 2.3-m (7.5-ft) silver sphere with a round hatch for the cosmonauts to enter and exit. A second round hatch covered the compartment that held the parachute used for returning to Earth.

Four metal straps and a bundle of power and control cables joined the capsule to the equipment module, which was shaped like two blunt cones joined at their bases. Green spherical oxygen tanks ringed Voskhod where the capsule joined the equipment module's top cone. The bottom half of the equipment module was covered by plates of heat-radiating material. The primary retrorocket was mounted on the bottom of the equipment module. A cylindrical backup retrorocket on top of the capsule helped ensure that Voskhod could return to Earth even if the primary retrorocket failed. The backup retrorocket was important because Voskhod operated at a higher altitude than Vostok; this meant that it would not fall back to Earth naturally after ten days, as Vostok would.

For the spacewalk on Voskhod 2, a special fabric airlock compartment called Volga was added. The collapsed airlock fit over the crew hatch during launch. In orbit it inflated, forming a tube 2.5 m (8.2 ft) long. The airlock was necessary because Voskhod's electronics were air-cooled. If the entire crew cabin was depressurized to allow the spacewalker to climb outside (as occurred on Gemini) the electronics would overheat. After the spacewalker entered the airlock, the commander closed the hatch behind him, then released the air from the airlock. The spacewalker then opened Volga's outer hatch to enter space. When the spacewalk was complete, the airlock was ejected.

The Voskhod spacecraft dropped out of orbit using one of its retrorockets. The equipment module and backup retrorocket detached and burned up in the atmosphere while a heat shield protected the capsule. As the capsule entered the dense lower part of the atmosphere, a single parachute opened. Just before touchdown a special landing rocket attached to the parachute lines fired to soften the capsule’s impact with Earth.