History of manned space exploration

The history of manned space exploration is essentially the history of the United States and Soviet/Russian space programs. Although the European Space Agency and China are expected to begin manned exploration of space in the early twenty-first century—manned exploration of space in the twentieth century resulted initially from a hotly contested "space race" that was, perhaps, the most visible of Cold War competitions between the Soviet and American superpowers. Initially driven by national pride and a quest for perceived strategic military advantage, over the last two decades, the exploration of space has become a more scientifically oriented and cooperative enterprise, especially in the ongoing joint construction of the International Space Station (ISS).

The official Soviet Space Program (SSP) began in May 1946, as it was then that the government made the decision to set up an industrial branch for missile "armamentation" in the Union of Soviet Socialist Republics (USSR).

The decision to create a space program, however, was not made overnight. Since the early 1930s in the USSR, small groups of enthusiasts attempted to create rockets. These groups were made up of engineers who afterwards would play leading roles in the Soviet Space Program; among them was Soviet aeronautical engineer Sergei Pavlovich Korolev (1906–1966). A victim of Soviet purges during the late 1930s, Korolev survived a term in Stalin's Gulag system to become the "Chief Designer" of the Soviet Space Program. Although during his lifetime Korolov's identity was never publicly revealed to western sources, Korolev became the eventual leader of most of the SSP projects.

The success of missile building in Nazi Germany, including the creation of the V-2 rocket, influenced the beginning of rocket system development in the USSR. Immediately after the end of the World War II, a group of Soviet engineers traveled to Germany, where they carefully studied captured German documents and equipment intended for missile creation. The group even worked in Germany for a time before returning to the USSR. By 1948, the P-1 missile was already developed (the analogue of V-2) and was officially accepted as the main armament in the Soviet army. In 1950, an improved version of this missile was created, and in 1951, the new P-2 missile was first created. By 1956, the army accepted the new missile, which could carry a nuclear charge and reach its target from a distance of about 932 mi (1,500 km).

The future United States space program also received an important boost from German scientists who either fled to the United States before the war, or who intentionally fled the advancing Soviet armies to surrender to United States and British forces. Notable among these scientists was Wernher von Braun (1912–1977). Greatly advancing the work of early American rocket designer Robert H. Goddard (1882–1945), and others, von Braun would become one of the chief architects of the American Space Program and go on to design the Saturn V rocket that ultimately achieved the escape velocities needed to propel America's Apollo program astronauts to the Moon .

In 1957, the two-stepped intercontinental ballistic missile P-7 was created in the USSR. Using this rocket, the world's first Earth-orbiting satellite , Sputnik, was launched on September 4, 1957 from the Baikonur cosmodrome (now in Kazakhstan). Sputnik weighed 187 lb (83.6 kg) and completed an elliptical orbit around the earth every 98 minutes. Sputnik was designed to return data about the composition and density of Earth's upper atmosphere. Sputnik transmitted via radio signals for approximately three weeks.

Also in the 1950s, the largest and most famous Soviet space vehicle-launching site, Baikonur, was built. This launching site is located in the Kazakhstan steppe, and the most important launches of Soviet/Russian spacecraft, in particular all spacecraft with men and women (cosmonauts) aboard, were launched from the Baikonur launch complex. Following the collapse of the USSR, the Baikonur launching site was located in an independent Kazakhstan, but Russia continues to rent and use the site for its space program.

The experimental research component of space study began under Korolev's supervision as early as 1949. Gradually, geophysics and meteorological rockets began to be launched, measurements of different geophysical field parameters at different heights were executed, and later, launching of rockets with animals on board were executed. Also in the 1950s, in parallel with military missile projects, work began on sending man into space. The result was the launch on April 12, 1961, of the spacecraft Vostok with the first cosmonaut, Yuri Gagarin. Aboard Vostok, Gagarin spent about one hour in space and completed one circuit around the earth. Shortly afterward, on August 6, 1961, the second cosmonaut, German Titov, flew to space on board the spacecraft Vostok 2, spending approximately one day orbiting the earth (Titov died in Moscow in 2000).

The launch of the first Sputnik and Gagarin's flight were triumphs of the Soviet Space Program, and the start of the unofficial space race with the Americans.

The effect on America of the spectacular early success of the Soviet Union in space exploration can rarely be overstated. Despite the design-based successes of Soviet-made MiG jet aircraft used against American forces during the Korean War, since 1947, when Charles E. "Chuck" Yeager (1923–) became the first man to break the sound barrier, America assumed it held a vast technological superiority over the Soviet Union in aeronautics and other science and engineering fields. Americans regarded the Soviet Union as nation with a struggling economy and often politically repressed scientific research programs (e.g., the debilitating effects of Lysenkoism—a Stalin-supported pseudoscientific interpretation of genetics that suppressed early Russian advances in genetics and contributed widespread Soviet agricultural shortages).

The Soviet launch of Sputnik and subsequently of launching the first man into orbit inflicted a deep wound to America's pride and assumed technological superiority. Near hysteria swept the American government as it feared—at a time of increasing nuclear tensions—that the demonstrated Soviet capabilities in peaceful space exploration would easily be translated into a destabilizing advantage in nuclear weapons delivery capability. Decimating the manpower and budgets of its successful high altitude aeronautics programs, the United States military and, after its founding in 1958, the National Aeronautics and Space Administration (NASA) accelerated rocket development programs. Moreover, the Soviet successes in space so rocked the American psyche that major reforms were undertaken in the educational system to close an apparent gap in scientific and engineering expertise. Education of scientists became a strategic national priority.

Although Soviet secrecy made direct comparisons difficult, the early record of the American space programs was notable for its very public failures. Rockets continually destroyed themselves in spectacular launch explosions. America's first attempted response to Sputnik, the Vanguard TV3 on December 6, 1957 ended in a launch failure. During 1958, four out of five intended American Pioneer probe missions (intended for lunar flybys) ended in launch failures.

Consistently behind the Soviet Union, the Americans finally successfully launched Explorer 1 on February 1, 1958. Weeks after Gagarin's orbital flight, on May 5, 1961, the United States launched its first astronaut, Alan B. Shepard Jr. into a sub-orbital flight from Cape Canaveral. It was not until February 20, 1962, that astronaut John Glenn became the first American to orbit the earth. Shepard's flight so captivated and buoyed Americans, that then U.S. President John F. Kennedy issued a challenge that America would dedicate the resources needed to land a man on the Moon and return him safely before the end of the 1960s.

Before America could complete its one-man Mercury program—a series of 20 unmanned and six manned flights designed principally to test elements of rocketry and whether humans could survive and work in space—the Soviet Union increased its number of "firsts" in space exploration. One of the lone bright spots for the American space program was the success of the Mariner 2 interplanetary probe. Launched in December 1962, Mariner passed within approximately 21,000 mi (33,800 km) of Venus and was able to transmit back to Earth the first useful data from an interplanetary probe.

On July 14–16, 1963, two spacecraft, Vostok 5 and Vostok 6, were launched with cosmonaut V. Bykovskii on board one, and with the first woman cosmonaut Valentina Tereshkova on board the second. On March 18, 1965, cosmonaut Aleksei Leonov was the first to go out in open space (spacewalk) from onboard the three-man Voskhod spacecraft.

On June 3, 1965, American astronaut Edward H. White II became the first American to "walk in space" (i.e., perform an Extra Vehicular Activity or EVA). White's tethered EVA was part of a methodical two-man Gemini program, designed to test equipment and refine skills in maneuver and rendezvous that would be required on subsequent three-man Apollo lunar missions. Although the Soviets maintained an impressive lead in space "firsts," it was during the Gemini program—consisting of 2 unmanned and 10 manned missions—that America gained the technological ability to move into the ambitious Apollo missions.

In contrast, despite being shrouded in secrecy, by the mid-1960s, the first failures of the Soviet Space Program were apparent. First launches of Soviet N-1 rockets (the rocket intended to take Soviet cosmonauts to the Moon) were not successful, and during tests, the rocket did not reach past an altitude of 70,000 ft (21,335 m). While the "Moon race" between the United States and the USSR continued, the Soviets spent vast amounts of money (equivalent to over 600 million U.S. 1969 dollars), but when it became obvious that the USSR would not win the race—i.e., it would not be able to be the first country which would land a man on the Moon—the Moon project stagnated and the remaining N-1 rockets were dismantled.

A devastating fire during a prelaunch test on January 27, 1967, killed three Apollo 1 astronauts and put NASA's quest to put a man on the moon by the end of the decade in jeopardy. The Soviet space program also encountered fatalities. During the first test of the Soyuz spacecraft in April 1967, cosmonaut V. M. Komarov was killed in a crash resulting from entangled parachute shroud lines. Another Soyuz accident occurred in June 1971, when a pressure leak during reentry killed all three Soyuz cosmonauts.

After a series of unmanned test flights, Americans returned to space on October 11, 1968, with the launch of Apollo 7. The success of the mission, and the stellar performance of the redesigned Apollo spacecraft put NASA on the fast track to a lunar mission. In December 1968, Apollo 8 astronauts Frank Borman, James A. Lovell Jr., and William A. Anders became the first manned spacecraft to leave Earth orbit when they traveled to the Moon and completed 10 orbits before returning to Earth. In March 1969, the flight of Apollo 9 remained in Earth orbit to successfully test the Lunar Excursion Module (LEM)—the first true spacecraft never designed to enter Earth's atmosphere. The 2-stage LEM was designed to carry astronauts from lunar orbit to the lunar surface and the upper stage was designed to return them to the Apollo command module that would remain in lunar orbit. In May, 1969, the flight of Apollo 10 tested the LEM in the lunar gravitational field, as astronauts undocked the LEM from the Apollo command module and flew within approximately 50,000 ft (15,420 m) of the lunar surface.

On July 16, 1969, the launch of Apollo 11 propelled astronauts Neil A. Armstrong (Commander), Edwin E. "Buzz" Aldrin, Jr. (Lunar Module Pilot), and Michael Collins (Command Module Pilot) toward the Moon. On July 20, 1969, Armstrong became the first man to set foot on another world. Armstrong and Aldrin left behind an American flag and a plaque that read: "Here Men From Planet Earth First Set Foot Upon the Moon. July 1969 A.D. We Came In Peace For All Mankind."

Having won the "space race," the American public's interest in lunar exploration quickly waned. Other than a renewed concern for the astronauts about the ill-fated Apollo 13 mission, public interest and the political will to continue to shoulder the financial burdens of lunar exploration brought the Apollo program to a halt after the flight of Apollo 17 in December, 1972.

Interestingly, it was only on the last flight of Apollo that a trained professional scientist—geologist astronaut Jack Schmitt—was able to conduct observations and conduct experiments on the lunar surface. Apollo 17's emphasis on lunar geology and science heralded a new age of space exploration.

Also frustrating and unsuccessful for the Soviets was the Soviet space shuttle project, begun in 1974. In the middle of the 1980s, an experimental version of the shuttle was created, the Buran, but the spacecraft executed only one flight in the automatic mode (without a pilot on board) on November 15, 1988. After the collapse of the USSR, work on this project was cut because of lack of funding.

One of the most successful projects of the Soviet Space Program, however, was the creation and work of the Mir orbital space station. Based on extensive experience with earlier Salyut space stations, Mir became the premier Earth orbiting laboratory. The base module of Mir, which weighed 36 tons (32.7 metric tons), was launched on February 20, 1986. In 1987, the Kvant module was linked up with the station; in 1990, the Kristall module was also linked up with the station, and in 1990, special equipment for docking of American shuttles in the station was placed aboard Mir.

For several years, Soyuz TM spacecraft with cosmonauts on board were regularly sent to Mir, changing crews after periods of about 5–6 months. After launch, the spacecraft docked with the Mir station after traveling in space for about two days. During several missions, the crews of the spacecraft and the station conducted joint exercises, and afterwards, the old crew "passed watch" to the new one. Several days after the spacecraft's arrival at the station, it returned to the earth with the crew who had finished the last watch.

Many scientific research projects were carried out on board Mir ; 73 persons from nine countries visited the station and it was calculated that the total time spent onboard by all the cosmonauts was about 40 years. During 1988, cosmonauts Musa Manrov and Vladimir Titov set records for what was then the longest period of time in space for humans (366 days). Subsequently, the longest flight record was extended to 438 days by cosmonaut Vladimir Polyakov. The duration of Mir's active status was much longer then expected. After ten years of utilization, different mechanical drawbacks occurred more frequently, and eventually the decision was made to end the project. The Soviet/Russian space station Mir was taken out of orbit and re-entered Earth's atmosphere in 2001; its fragments sank in the Pacific Ocean.

Following the Apollo lunar program, the United States completed a more modest Skylab program. In a welcome deescalation of Cold War tensions in 1975, the U.S. and Soviet Space programs cooperated in a joint Apollo-Soyuz rendezvous and docking mission. The mission was designed to pave the way for future cooperation in spaceflight.

NASA development of the Space Transportation System (STS)—the Space Shuttle—has made space more accessible to a wider variety of scientists and experts. The space shuttle has become the American workhorse for orbital delivery of wide range of satellites and repair of science instruments (e.g., the Hubble Space Telescope ). America's first shuttle, Columbia, was launched in April, 1981.

In January 1986, a disastrous explosion 73 seconds after liftoff destroyed the space shuttle Challenger. The explosion was due to a faulty "O" ring—a ring sealing joints in the segmented solid rock boosters—that was made less flexible by the cold weather conditions prevailing during the launch sequence. A ring failure allowed hot gasses to escape the right solid rocket booster and then to burn through to the main auxiliary fuel tank used at liftoff. The explosion claimed the life of the seven-member crew—including America's first teacher in space, astronaut Christa McAuliffe—and halted manned U.S. space flight for more than two years. In general, after the collapse of the USSR, the Russian space program was reduced and only recently began a revival. In spite of many different difficulties, Russia participated in the project of creating and utilizing the International Space Station. The first module (Zarya ) of the ISS was created in Russia and launched on November 20, 1998, from Baikonur.

On December 4, 1998, the United States shuttle Endeavor was launched, carrying the ISS module Unity. American and Russian astronauts joined the two modules in open space. This event marked the beginning of the International Space Program (ISP), the official opening of which occurred on December 10, 1998. Construction of and research aboard the ISS continues.

See also History of exploration I (Ancient and classical); History of exploration II (Age of exploration); History of exploration III (Modern era); Hubble Space Telescope (HST); Space and planetary geology; Space physiology; Space probe; Spacecraft, manned