Human spaceflight

Human spaceflight (also referred to as crewed spaceflight, or more historically manned spaceflight) is spaceflight with a crew or passengers aboard a spacecraft, often with the spacecraft being operated directly by the onboard human crew. Spacecraft can also be remotely operated from ground stations on Earth, or autonomously, without any direct human involvement. People trained for spaceflight are called astronauts (American or other), cosmonauts (Russian), or taikonauts (Chinese); and non-professionals are referred to as spaceflight participants or spacefarers.

The first human in space was Soviet cosmonaut Yuri Gagarin, who launched as part of the Soviet Union's Vostok program on 12 April 1961 at the beginning of the Space Race. On 5 May 1961, Alan Shepard became the first American in space, as part of Project Mercury. Humans traveled to the Moon nine times between 1968 and 1972 as part of the United States' Apollo program, and have had a continuous presence in space for 24 years and 362 days on the International Space Station (ISS). On 15 October 2003, the first Chinese taikonaut, Yang Liwei, went to space as part of Shenzhou 5, the first Chinese human spaceflight. As of March 2025, humans have not traveled beyond low Earth orbit since the Apollo 17 lunar mission in December 1972.

Currently, the United States, Russia, and China are the only countries with public or commercial human spaceflight-capable programs. Non-governmental spaceflight companies have been working to develop human space programs of their own, e.g. for space tourism or commercial in-space research. The first private human spaceflight launch was a suborbital flight on SpaceShipOne on June 21, 2004. The first commercial orbital crew launch was by SpaceX in May 2020, transporting NASA astronauts to the ISS under United States government contract.

Human spaceflight capability was first developed during the Cold War between the United States and the Soviet Union (USSR). These nations developed intercontinental ballistic missiles for the delivery of nuclear weapons, producing rockets large enough to be adapted to carry the first artificial satellites into low Earth orbit.

After the first satellites were launched in 1957 and 1958 by the Soviet Union, the US began work on Project Mercury, with the aim of launching men into orbit. The USSR was secretly pursuing the Vostok program to accomplish the same thing, and launched the first human into space, the cosmonaut Yuri Gagarin. On 12 April 1961, Gagarin was launched aboard Vostok 1 on a Vostok 3KA rocket and completed a single orbit. On 5 May 1961, the US launched its first astronaut, Alan Shepard, on a suborbital flight aboard Freedom 7 on a Mercury-Redstone rocket. Unlike Gagarin, Shepard manually controlled his spacecraft's attitude. On 20 February 1962, John Glenn became the first American in orbit, aboard Friendship 7 on a Mercury-Atlas rocket. The USSR launched five more cosmonauts in Vostok capsules, including the first woman in space, Valentina Tereshkova, aboard Vostok 6 on 16 June 1963. Through 1963, the US launched a total of two astronauts in suborbital flights and four into orbit. The US also made two North American X-15 flights (90 and 91, piloted by Joseph A. Walker), that exceeded the Kármán line, the 100 kilometres (62 mi) altitude used by the Fédération Aéronautique Internationale (FAI) to denote the edge of space.

In 1961, US President John F. Kennedy raised the stakes of the Space Race by setting the goal of landing a man on the Moon and returning him safely to Earth by the end of the 1960s. That same year, the US began the Apollo program of launching three-man capsules atop the Saturn family of launch vehicles. In 1962, the US began Project Gemini, which flew 10 missions with two-man crews launched by Titan II rockets in 1965 and 1966. Gemini's objective was to support Apollo by developing American orbital spaceflight experience and techniques to be used during the Moon mission.

Meanwhile, the USSR remained silent about their intentions to send humans to the Moon and proceeded to stretch the limits of their single-pilot Vostok capsule by adapting it to a two or three-person Voskhod capsule to compete with Gemini. They were able to launch two orbital flights in 1964 and 1965 and achieved the first spacewalk, performed by Alexei Leonov on Voskhod 2, on 8 March 1965. However, the Voskhod did not have Gemini's capability to maneuver in orbit, and the program was terminated. The US Gemini flights did not achieve the first spacewalk, but overcame the early Soviet lead by performing several spacewalks, solving the problem of astronaut fatigue caused by compensating for the lack of gravity, demonstrating the ability of humans to endure two weeks in space, and performing the first space rendezvous and docking of spacecraft.

The US succeeded in developing the Saturn V rocket necessary to send the Apollo spacecraft to the Moon, and sent Frank Borman, James Lovell, and William Anders into 10 orbits around the Moon in Apollo 8 in December 1968. In 1969, Apollo 11 accomplished Kennedy's goal by landing Neil Armstrong and Buzz Aldrin on the Moon on 21 July and returning them safely on 24 July, along with Command Module pilot Michael Collins. Through 1972, a total of six Apollo missions landed 12 men to walk on the Moon, half of which drove electric powered vehicles on the surface. The crew of Apollo 13—Jim Lovell, Jack Swigert, and Fred Haise—survived an in-flight spacecraft failure, they flew by the Moon without landing, and returned safely to Earth.