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Space exploration
Human beings enter space


Human beings enter space

In 1958, scientists in the United States and the Soviet Union began serious efforts to design a spacecraft that could carry human beings. Both nations chose to develop a wingless capsule atop a launch vehicle that would consist of a modified long-range missile. The prospect of human beings traveling in space greatly worried scientists. Tests with animals had shown that space travel probably involved no physical danger, but there were serious concerns about possible psychological hazards. Some experts feared that the stresses of launch, flight, and landing might drive a space traveler to terror or unconsciousness.

Vostok and Mercury: The first human beings in space

The Soviet Union's Vostok (East) program and the Mercury program of the United States represented the first efforts to send a human being into space. The Vostok capsule weighed about 10,000 pounds (4,500 kilograms). It was to be carried into orbit atop a modified R-7 missile. The capsule consisted of a spherical pilot's cabin and a cylindrical service module, the section containing the propulsion system. An ejection seat was designed to provide an escape for the astronaut in case of a mishap during launch. The life-support system used a mixture of oxygen and nitrogen similar to the atmosphere at sea level.

The U.S. Mercury capsule weighed about 3,000 pounds (1,360 kilograms) and was to be carried into space atop a Redstone or Atlas rocket. The cone-shaped capsule would use parachutes to land in the ocean, where the water would provide extra cushioning. The life-support system used pure oxygen at low pressure. In the event of a booster malfunction during launch, the capsule and pilot would be pulled free by a solid-fuel rocket attached to the nose of the capsule.

While U.S. plans proceeded in the glare of publicity, Soviet developments took place in great secrecy. Both nations made unpiloted orbital tests in 1960 and 1961, some of which suffered booster failures. Both nations also sent animals into space during this period. One of these animals was a chimpanzee named Ham, who made an 18-minute flight in a Mercury capsule on Jan. 31, 1961.

The first fatality in a piloted space program occurred on March 23, 1961. A Soviet cosmonaut trainee named Valentin V. Bondarenko burned to death in a pressure chamber fire. Soviet officials covered up the accident.

The first human being in space was a Soviet air force pilot named Yuri A. Gagarin. He was launched aboard Vostok (later referred to as Vostok 1) on April 12, 1961. In 108 minutes, Gagarin orbited Earth once and returned safely. An automatic flight control system managed the spacecraft's operations during the entire flight. A 25-hour, 17-orbit flight by cosmonaut Gherman Titov aboard Vostok 2 followed in August of that year.

The Mercury program made its first piloted flight on May 5, 1961, when a Redstone rocket launched astronaut Alan B. Shepard, Jr., in a capsule he named Freedom 7. Shepard flew a 15-minute suborbital mission-that is, a mission that did not reach the speed and altitude required to orbit Earth.

A suborbital flight on July 21, 1961, by astronaut Virgil I. Grissom almost ended tragically. The Mercury capsule's side hatch opened too soon after splashdown in the Atlantic Ocean, and the spacecraft rapidly filled with water. Grissom managed to swim to safety.

On Feb. 20, 1962, John H. Glenn, Jr., became the first American to orbit Earth. Glenn completed three orbits in less than five hours. He pointed his capsule in different directions, tested its various systems, and observed Earth.

Three months later, astronaut M. Scott Carpenter repeated Glenn's three-orbit mission. A six-orbit mission by Walter M. Schirra, Jr., in October 1962 further extended the testing of the spacecraft. The final Mercury mission took place in May 1963, with L. Gordon Cooper aboard. The mission lasted 11/2 days.

Meanwhile, the Soviet Union continued to launch Vostok missions. In August 1962, Vostok 3 and Vostok 4 lifted off just a day apart and passed near each other in space. Another two capsules-Vostok 5 and Vostok 6-were launched in June 1963. One of the pilots spent almost five days in orbit, a new record. The other pilot, Valentina Tereshkova, became the first woman in space.

Voskhod and Gemini: The first multiperson space flights

In 1961, the United States announced the Gemini program, which would send two astronauts into space in an enlarged version of the Mercury capsule. This announcement spurred Soviet planners to modify their Vostok capsule to carry up to three cosmonauts. Political pressure to upstage U.S. efforts was so intense that Soviet engineers sacrificed certain safety features, such as ejection seats, to enlarge the capsule.

The world's first multiperson space capsule, Voskhod (Sunrise)-later referred to as Voskhod 1-was launched on Oct. 12, 1964. Cosmonauts Vladimir M. Komarov, Konstantin P. Feoktistov, and Boris B. Yegorov spent 24 hours in orbit. They became the first space travelers to land inside their capsule on the ground, rather than in the ocean.

In March 1965, cosmonaut Alexei A. Leonov stepped through an inflatable air lock attached to Voskhod 2 to become the first person to walk in space. After the capsule's automatic flight control system failed, Leonov and Pavel I. Belyayev had to land it manually. They missed their planned landing zone and came down in an isolated forest. The cosmonauts had to fend off hungry wolves until rescuers reached them the following day.

The first piloted Gemini mission, Gemini 3, was launched on March 23, 1965. Astronauts Grissom and John W. Young used the capsule's maneuvering rockets to alter its path through space. With Gemini 4, launched on June 3, 1965, copilot Edward H. White II became the first American to walk in space. The astronauts aboard Gemini 5, launched on Aug. 21, 1965, spent almost eight days in space, a record achieved by using fuel cells to generate electricity.

Gemini 6 was originally intended to link up with an Agena rocket sent into space a few hours earlier. After the unpiloted Agena was lost in a booster failure, NASA combined Gemini 6 with an already scheduled 14-day Gemini 7 mission. Gemini 7 was launched as planned, on Dec. 4, 1965, and Gemini 6 took off 11 days later. Within hours, Schirra and Thomas P. Stafford moved their spacecraft to within 1 foot (30 centimeters) of Gemini 7 and its crew, Frank Borman and James A. Lovell, Jr. The two spacecraft orbited Earth together for several hours before separating.

On March 16, 1966, Gemini 8 completed the world's first docking of two space vehicles when it linked up with an Agena rocket in space. However, the spacecraft went into a violent tumble. Astronauts Neil A. Armstrong and David R. Scott managed to regain control of the spacecraft and make an emergency splashdown in the western Pacific Ocean.

Additional tests of docking and extravehicular activity took place on the remaining four Gemini missions. On these missions, astronauts and flight controllers also gained vital experience in preparation for the tremendous challenges of piloted lunar flight.

Contributor: James Oberg, M.S., Spaceflight Engineer; author, UFOs and Outer Space Mysteries.
Source : World Book 2005

Space exploration
What is space?
Getting into space and back
Living in space
Meeting basic needs in space
Communicating with Earth
The dawn of the space age
Space probes
Probes to Venus
Probes to Jupiter and beyond
Probes to comets
Human beings enter space
Apollo: Mission to the moon
Exploring the moon
Returning to Earth
The International Space Station
Space shuttles
Types of shuttle missions