Human spaceflight

• 1. Introduction

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  Human spaceflight has been continuous since the 2nd of November 2000, when the first crew boarded the International Space Station and never fully left. For more than two decades, humans have maintained an unbroken presence in orbit, passing the torch from crew to crew without a single gap. But that constancy obscures how improbable it all was. The story begins not with cooperation, but with nuclear anxiety, and the question of who would reach space first between two superpowers who had just built rockets capable of ending civilization. What followed was a race that put the first human in orbit, landed men on the Moon, killed crews in training and in flight, and eventually gave way to a commercial industry that now sells tickets beyond the Karman line. How did a Cold War arms program become humanity's permanent address in space? And who got left out along the way?

• 2. The Race Begins

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  On the 12th of April 1961, Soviet cosmonaut Yuri Gagarin lifted off aboard Vostok 1 on a Vostok 3KA rocket and completed a single orbit of Earth. He was the first human in space, and the Soviet Union had beaten the United States to the milestone without warning. The Americans had been working on Project Mercury, aiming to launch men into orbit, but the USSR had been pursuing the Vostok program in secrecy. Less than a month later, on the 5th of May 1961, Alan Shepard flew a suborbital arc aboard Freedom 7 on a Mercury-Redstone rocket, becoming the first American in space. Unlike Gagarin, Shepard manually controlled his spacecraft's attitude. John Glenn followed on the 20th of February 1962, orbiting Earth aboard Friendship 7 on a Mercury-Atlas rocket, becoming the first American to reach orbit. The Soviets continued accumulating firsts: five more cosmonauts flew in Vostok capsules, including Valentina Tereshkova aboard Vostok 6 on the 16th of June 1963, the first woman in space. Two North American X-15 flights by Joseph A. Walker also crossed the Karman line, the 100-km altitude boundary used by the Federation Aeronautique Internationale to mark the edge of space. That boundary would become a contested line in the commercial era, but in 1963 the race to cross it was entirely a government affair between two nations pointing missiles at each other.

• 3. Apollo and the Moon

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  In 1961, US President John F. Kennedy publicly committed to landing a man on the Moon and returning him safely by the end of the decade. That single speech redirected billions of dollars and set the pace for the entire decade of American spaceflight. Project Gemini, begun in 1962, flew ten missions with two-man crews on Titan II rockets in 1965 and 1966. Its purpose was to build the orbital skills Apollo would need: spacewalks, rendezvous, docking, and endurance. The USSR competed by cramming extra cosmonauts into an adapted Vostok capsule called Voskhod. Alexei Leonov performed the first spacewalk from Voskhod 2 on the 8th of March 1965. But the Voskhod could not maneuver in orbit the way Gemini could, and the program ended. The Americans solved the problem of astronaut fatigue in zero gravity, demonstrated two weeks of human endurance in orbit, and performed the first space rendezvous and docking. Apollo 8 carried Frank Borman, James Lovell, and William Anders into ten orbits around the Moon in December 1968. Then on the 20th of July 1969, Neil Armstrong and Buzz Aldrin landed on the Moon during Apollo 11, with Michael Collins holding position in the Command Module. They returned safely on the 24th of July. Through 1972, a total of six Apollo missions landed twelve men on the lunar surface, and half of those crews drove electric-powered vehicles across it. The crew of Apollo 13, Jim Lovell, Jack Swigert, and Fred Haise, survived an in-flight oxygen tank failure, flew by the Moon without landing, and returned to Earth using the lunar lander as a lifeboat. Meanwhile, the Soviets pursued their own crewed lunar program in secret. They developed the three-person Soyuz spacecraft but failed to build the N1 rocket capable of a human lunar landing, and quietly discontinued their lunar ambitions in 1974.

• 4. Stations, Shuttles, and Détente

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  After the Moon race, the US and USSR took divergent paths that eventually converged. In 1969, President Nixon appointed Spiro Agnew to lead a Space Task Group that proposed an ambitious Space Transportation System: a reusable shuttle, a permanent space station, a reusable space tug, a nuclear interplanetary ferry, and a human Mars mission as early as 1986. Nixon approved only the Shuttle. Plans were scaled back repeatedly, replacing the piloted booster with solid rocket boosters and substituting an expendable external tank for the planned fully reusable design. The Soviets, after losing the Moon race, concentrated on space stations. They launched a series of Salyut sortie stations from 1971 to 1986, and three disguised Almaz military stations from 1973 to 1977. During this same period, Nixon and Soviet General Secretary Leonid Brezhnev were negotiating détente. The Apollo-Soyuz mission of 1975 was one result: an Apollo spacecraft with a special docking adapter rendezvoused with Soyuz 19, and the American and Soviet crews shook hands in orbit. The purpose was purely symbolic, and the two nations continued competing. The Space Shuttle began flying in 1981. Four shuttles were built: Columbia, Challenger, Discovery, and Atlantis. From 1983 to 1998, twenty-two Shuttle flights carried components for a European Space Agency science facility called Spacelab in the payload bay. Challenger was destroyed during launch on the 28th of January 1986, killing all seven crew members, 73 seconds after liftoff when a solid rocket booster seal failed in extreme cold. A fifth shuttle, Endeavour, was built to replace it. The Soviets built their own shuttle called Buran, capable of robotic orbital flight and landing but carrying no main engines of its own. A single uncrewed orbital test flight took place in November 1988. The program was canceled after the dissolution of the Soviet Union in 1991. The one orbiter that had flown was destroyed in a hangar roof collapse in May 2002.

• 5. China Enters Orbit

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  On the 14th of July 1967, Mao Zedong and Zhou Enlai decided China should not be left out of the space age and launched the top-secret Project 714, which aimed to put two people in space by 1973 using the Shuguang spacecraft. Nineteen People's Liberation Army Air Force pilots were selected for training in March 1971. The program was canceled on the 13th of May 1972 for economic reasons, and two subsequent crewed spacecraft concepts also came to nothing. In 1992, under the China Manned Space Program, also known as Project 921, China authorized a third attempt. The Shenzhou spacecraft and Long March 2F rocket were developed alongside new launch infrastructure. Shenzhou 1, the first uncrewed test spacecraft, launched on the 20th of November 1999 and was recovered the next day. Three more uncrewed missions followed to verify key technologies. On the 15th of October 2003, Shenzhou 5 carried Yang Liwei into orbit for 21 hours and returned him safely to Inner Mongolia, making China the third nation to independently launch a human into orbit. China then pursued spacewalking, rendezvous, and docking capabilities. On the 25th of September 2008, Zhai Zhigang and Liu Boming completed China's first spacewalk during the flight of Shenzhou 7. China's first automatic rendezvous and docking was completed on the 3rd of November 2011, between Tiangong 1 and the uncrewed Shenzhou 8. Liu Yang, China's first female astronaut, flew aboard Shenzhou 9 for the first manual docking. The Tiangong Space Station followed, with its Tianhe core module launched by the Long March 5B rocket on the 29th of April 2021.

• 6. Who Gets to Go

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  Valentina Tereshkova flew in 1963, but it was not until the 1980s that another woman reached space. The reason had an institutional cause: all astronauts were required to be military test pilots at the time, a career women could not enter. After the rules changed, Svetlana Savitskaya became the second woman in space. Sally Ride followed as the first American woman in the program. The first all-female spacewalk did not occur until 2019, when Christina Koch and Jessica Meir conducted it together. Both had previously participated in separate spacewalks with NASA. During Artemis II in 2026, Koch became the first woman to travel beyond low Earth orbit. The first lunar surface mission with a woman aboard is planned for 2028. The numbers remain stark: more than 600 people have flown in space, but only 75 have been women. Agencies have at times limited women to half as much time in space as men, on the stated basis of cancer risk assumptions. A shortage of space suits sized for female astronauts has also constrained the missions women are eligible for. Representation by nationality expanded gradually. Vladimír Remek of Czechoslovakia became the first non-American and non-Soviet person in space on the 2nd of March 1978, through the Soviet Interkosmos program. Citizens from 38 nations have since flown in space aboard Soviet, American, Russian, and Chinese spacecraft. The Justspace Alliance and the IAU-featured Inclusive Astronomy organization have formed in recent years to push for broader human representation in spaceflight.

• 7. Commercial Spaceflight

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  SpaceShipOne made the first private human spaceflight launch on the 21st of June 2004, reaching space on a suborbital trajectory. The commercial era that followed took two decades to become operational. SpaceX flew its first crewed orbital mission, the Demo-2, in May 2020, transporting NASA astronauts to the International Space Station under US government contract. A tourist mission called Inspiration4 launched in September 2021. Blue Origin flew its New Shepard vehicle on its first crewed flight on the 20th of July 2021, carrying founder Jeff Bezos, his brother Mark Bezos, aviator Wally Funk, and 18-year-old Oliver Daemen. As of May 2025, Blue Origin had conducted thirty-one launches including twenty uncrewed test flights and eleven crewed flights. Virgin Galactic's SpaceShipTwo reached space in December 2018. Boeing developed the Starliner capsule as part of NASA's Commercial Crew Development program, with its first crewed flight launching in June 2024. SpaceX is also developing Starship, a fully reusable two-stage system, with a first integrated test flight in April 2023. Starship has been proposed for point-to-point Earth travel carrying more than 100 passengers suborbitorally between two locations in under one hour.

• 8. The Hazards of Space

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  Twenty-three crew members have died in accidents aboard spacecraft. Over 100 others have died in accidents during activities directly related to spaceflight or testing. The fatalities cluster around a few recurring failure modes: fire in pure oxygen environments, parachute and reentry failures, launch abort system gaps, and the catastrophic loss of structural integrity. An electrical fire in the cabin of Apollo 1 killed Gus Grissom, Ed White, and Roger Chaffee on the 27th of January 1967 during a ground test, because the high-pressure pure oxygen atmosphere allowed it to spread too rapidly to permit escape. The Soyuz 1 pilot Vladimir Komarov was killed on the 24th of April 1967 when his capsule's parachutes failed. The crew of Soyuz 11 were asphyxiated on the 30th of June 1971 when a cabin ventilation valve was jolted open at 168 km altitude by the shock of explosive separation bolts that fired simultaneously rather than sequentially. Pressure became fatal within about 30 seconds. Beyond the accidents on record, ongoing physiological hazards affect every crew member in orbit. Astronauts can lose up to twenty per cent of their muscle mass on flights lasting five to eleven days. Upon returning from long missions, they are not allowed to drive a car for twenty-one days. MRI studies reported in 2017 found significant changes in the position and structure of the brain in astronauts who had traveled in space, with longer missions producing greater changes. Radiation beyond low Earth orbit presents a separate threat: a solar storm in August 1972, between Apollo 16 and Apollo 17, could have caused acute radiation sickness or death for any astronaut caught in extravehicular activity or on the lunar surface at the time. Valeri Polyakov holds the record for the longest single spaceflight, from the 8th of January 1994 to the 22nd of March 1995, 437 days, 17 hours, 58 minutes, and 16 seconds. Oleg Kononenko has accumulated the most total time in space across multiple missions: 1,110 days, 14 hours, and 57 minutes.