The space program “Vostok" (East) — was the Soviet program intended to create a series of single piloted spacecraft for flights on a circumterraneous orbit. Several spaceships of the name “Vostok" were created under direction of general designer, Sergey Pavlovich Korolyov from 1958 to 1963.
Work on creation of the piloted ship demanded deep study of such new areas as descent in an atmosphere, creation of reliable heat-shielding, hypersonic aerodynamics etc. In particular, it has been noted that ballistic descent from an orbit can result in a 10G load on the astronaut.
During the medical research conducted in April, 1958, several tests on pilots in a centrifuge had shown that at certain positions, the human body is capable of withstanding loads up to 10G without serious consequences for the health of the person. It had predetermined a choice of the spherical form for the first piloted ship, as it allowed the desired position and had the least problems when dealing with various "attack angles" in aspects of drag and lift-to-drag ratio. The most comprehensible way of returning of a cosmonaut was ejection at height of several kilometers and the further descent with a parachute.
First piloted "Vostok" flight, which took place on April, 12th, 1961, became the first-ever space vehicle to carry a person into space. The day of April, 12th, is marked in the Soviet Union – now Russia - and in many other countries of the world, as the World Day of Aircraft and Astronautics.
The first "Vostok" that was piloted by Yury Gagarin made only 1 revolution around the Earth, having flown about our planet for 108 minutes. Flight of the ship, Vostok-5, with cosmonaut Valery Bykovsky lasted about 5 days. During this voyage the ship and cosmonaut orbited the Earth 81 times. At the same time, Vostok-6, the last spacecraft of the series, was piloted by Valentina Tereshkova, first woman in space. It was also the first time that 2 ships were in orbit simultaneously.