Edward White on a spacewalk during the Gemini 4 mission.

As of 2008, only United States Space Shuttle program, the Russian Soyuz programme, and the Chinese Shenzhou program are actively launching human spaceflights.

Early attempts at human spaceflight

At around 125 AD, a Greek satirist named Lucian wrote a book on space flight called True Histories^[1]. The book was full of tall, unbelieveable tales and travelogues on visits to the sun and the moon. Today, the book could easily be discarded as the fantasy of a people of a bygone era. But it was significant in the sense that it kindled the curiosities of the people of the day and stimulated interest in outer space and space travel.

In 1638, a Christian writer from England named Wilkins wrote a book on moon travel and suggested four methods to accomplish it. Firstly, he said, the divine soul could take man to the moon; secondly, some large and powerful birds could transport man to the moon; thirdly, man himself could make the journey by tying wings to his arms and fourthly, he said, a flying machine could transport man to the moon.

American author Herbert S. Zim claimed in 1945^[2] that there is a Chinese legend where a scientist named Wan Hu^[3] in the early Ming dynasty attempted to travel through space with the help of rockets. In the story, Wan tied 47 rockets filled with explosives to the chair in which he was sitting and ignited them. There was a large explosion, but when the smoke cleared Wan Hu was gone and never seen again.

History

The first human spaceflight was undertaken on April 12, 1961, when cosmonaut Yuri Gagarin made one orbit around the Earth aboard the Vostok 1 spacecraft launched by the Soviet Union. Valentina Tereshkova became the first woman in space on board Vostok 6 on June 16, 1963. Both spacecraft were launched by Vostok 3KA launch vehicles. Alexei Leonov made the first spacewalk when he left the Voskhod 2 on March 8 1965. Svetlana Savitskaya became the first woman to do so on July 25, 1984.

The United States became the second nation (and for four decades, one of only two) to achieve manned spaceflight, with the suborbital flight of astronaut Alan Shepard aboard Freedom 7, carried out as part of Project Mercury. The spacecraft was launched on May 5, 1961 on a Redstone rocket. The first U.S. orbital flight was that of John Glenn aboard Friendship 7, which was launched February 20, 1962 on an Atlas rocket. Since April 12, 1981 the U.S. has conducted all its human spaceflight missions with reusable Space Shuttles. Sally Ride became the first American woman in space in 1983. Eileen Collins was the first female Shuttle pilot, and with Shuttle mission STS-93 in July 1999 she became the first woman to command a U.S. spacecraft.

The People's Republic of China became the third nation to acheive human spaceflight when astronaut Yang Liwei launched into space on a Chinese-made vehicle, the Shenzhou 5, on October 15, 2003. This flight made China the third nation capable of launching its own manned spacecraft using its own launcher. Previous European (Hermes) and Japanese (HOPE-X) domestic manned programs were abandoned after years of development, as was the first Chinese attempt, the Shuguang spacecraft.

The furthest destination for a human spaceflight mission has been the Moon, and as of 2007 the only missions to the Moon have been those conducted by NASA as part of the Apollo program. The first such mission, Apollo 8, orbited the Moon but did not land. The first Moon landing mission was Apollo 11, during which -- on July 20, 1969 -- Neil Armstrong became the first person to set foot on the Moon. Six missions landed in total, numbered Apollo 11?17, excluding Apollo 13. Altogether twelve men reached the Moon's surface, the only humans to have been on an extraterrestrial body. The Soviet Union discontinued its program for lunar orbiting and landing of human spaceflight missions on June 24, 1974 when Valentin Glushko became General Designer of NPO Energiya.^[4]

The longest single human spaceflight is that of Valeriy Polyakov, who left earth on January 8, 1994, and didn't return until March 22, 1995 (a total of 437 days 17 hr. 58 min. 16 sec. aboard). Sergei Krikalyov has spent the most time of anyone in space, 803 days, 9 hours, and 39 seconds altogether. The longest perdiod of continuous human presence in space lasted as long as 3,644 days, eight days short of 10 years, spanning the launch of Soyuz TM-8 on September 5, 1989 to the landing of Soyuz TM-29 on August 28, 1999.

For many years beginning in 1961, only two countries, the USSR (later Russia) and United States, had their own astronauts. Later, cosmonauts and astronauts from other nations flew in space, beginning with the flight of Vladimir Remek, a Czech, on a Soviet spacecraft on March 2 1978. As of 2007, citizens from 33 nations (including space tourists) have flown in space aboard Soviet, American, Russian, and Chinese spacecraft.

Space programs

As of 2007, human spaceflight missions have been conducted by the Soviet Union (/Russia), the United States, the People's Republic of China and by the private spaceflight company Scaled Composites.

Several other countries and space agencies have announced and begun human spaceflight programs by their own technology, including Japan (JAXA), India (ISRO), Iran (ISA), Malaysia (MNSA) and Turkey.

Currently the following spacecraft and spaceports are used for launching human spaceflights:

• Soyuz with Soyuz launch vehicle?Baikonur Cosmodrome
• Space Shuttle?Kennedy Space Center
• International Space Station (ISS)?Assembled in orbit; crews transported by the previous two spacecraft
• Shenzhou spacecraft with Long March rocket?Jiuquan Satellite Launch Center

Historically, the following spacecraft and spaceports have also been used for human spaceflight launches:

• Vostok?Baikonur Cosmodrome
• Mercury?Kennedy Space Center
• Voskhod?Baikonur Cosmodrome
• X-15?Edwards Air Force Base,^[5]

(two internationally recognized suborbital flights in program)

• Gemini?Kennedy Space Center
• Apollo?Kennedy Space Center
• Salyut space station?Baikonur Cosmodrome
• Almaz space station?Baikonur Cosmodrome
• Skylab space station?Kennedy Space Center
• Mir space station?Baikonur Cosmodrome
• SpaceShipOne with White Knight?Mojave Spaceport

Numerous private companies attempted human spaceflight programs in an effort to win the $10 million Ansari X Prize. The first private human spaceflight took place on June 21, 2004, when SpaceShipOne conducted a suborbital flight. SpaceShipOne captured the prize on October 4, 2004, when it accomplished two consecutive flights within one week.

Most of the time, the only humans in space are those aboard the ISS, whose crew of three spends up to six months at a time in low Earth orbit.

NASA and ESA now use the term "human spaceflight" to refer to their programs of launching people into space. Traditionally, these endeavors have been referred to as "manned space missions".

National spacefaring attempts

Safety concerns

Planners of human spaceflight missions face a number of safety concerns.

Life support

The immediate needs for breathable air and drinkable water are addressed by the life support system of the spacecraft.

Adverse effects of radiation

The effect of radiation on space travelers depends on two main factors: the intensity of the radiation, and the time over which the exposure occurs. Astronauts in low earth orbit are exposed to radiation of relatively low intensity for long periods of time. The Apollo astronauts were exposed to much more intense radiation, but only for a matter of days. Astronauts on hypothetical future interplanetary missions would be exposed to high intensities for long periods, causing the accumulation of very large doses; this is currently one of the most important unsolved problems facing planners of such efforts.

Adverse effects of the microgravity environment

Medical data from astronauts in low earth orbits for long periods, dating back to the 1970s, show several adverse effects of a microgravity environment: loss of bone density, decreased muscle strength and endurance, postural instability, and reductions in aerobic capacity. Over time these deconditioning effects can impair astronauts? performance or increase their risk of injury.^[7]

Launch safety

Reentry safety

Reliability

References

See also

Lists

• List of astronauts by name
• List of human spaceflights
• List of human spaceflights by program
• List of manned spacecraft
• List of space agencies
• List of space disasters
• List of spacewalks

External links

• NASA Human Space Flight
• Official Constellation NASA Web Site
• Official Orion NASA Web Site
• Official Ares NASA Web Site
• Human Spaceflight Profile by NASA's Solar System Exploration
• Transitioning to the NASA Constellation Program
• U.S. Spaceflight History

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