Human spaceflight

Edward White on a spacewalk during the Gemini 4 mission

Human spaceflight is spaceflight with a human crew and possibly passengers. This makes it unlike robotic space probes or remotely-controlled satellites. Human spaceflight is sometimes called manned spaceflight, a term now deprecated by major space agencies in favor of its gender-neutral alternative.

The first human spaceflight was accomplished on April 12, 1961 by Soviet cosmonaut Yuri Gagarin. The only countries to have independent human spaceflight capability are Russia, United States and China. As of 2010, human spaceflights are being actively launched by the Soyuz programme conducted by the Russian Federal Space Agency, the Space Shuttle program conducted by NASA, and the Shenzhou program conducted by the China National Space Administration.

The US will lose governmental human spaceflight launch capability upon retirement of the Space Shuttle, expected in 2011. Under the Bush administration, the Constellation program included plans for canceling the Shuttle and replacing it with the capability for spaceflight beyond low Earth orbit. In the 2011 United States federal budget, the Obama administration proposed canceling Constellation. Under the new plan, NASA would rely on transportation services provided by the private sector, such as Space X's Falcon 9. The period between the retirement of the Shuttle and the initial operational capability of new systems (either Constellation or the new commercial proposals), similar to the gap between the cancellation of Apollo and the first Space Shuttle flight, is often referred to as the human spaceflight gap.

In recent years there has been a gradual movement towards more commercial forms of spaceflight. A number of non-governmental startup companies have sprung up in recent years, hoping to create a space tourism industry. For a list of such companies, and the spacecraft they are currently building, see list of space tourism companies. NASA has also tried to stimulate private spaceflight through programs such as Commercial Crew Development (CCDev) and Commercial Orbital Transportation Services (COTS). With its 2011 budget proposals released in early February 2010^[1], the Obama administration is moving towards a model where commercial companies would supply NASA with transportation services of both crew and cargo to low Earth orbit. The vehicles used for these services would then serve both NASA and potential commercial customers. NASA intends to spend $6 billion in the coming years to develop commercial crew vehicles, using a model similar to that used under COTS.^[2]

History

First human spaceflights

Yuri Gagarin, the first man in space, in his space suit during the Vostok 1 mission

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 space program and designed by the rocket scientist Sergey Korolyov. 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.

Buzz Aldrin on the surface of the Moon during Apollo 11

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 achieve human spaceflight when Yang Liwei launched into space on a Chinese-made vehicle, the Shenzhou 5, on October 15, 2003. The flight made China the third nation to have launched 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 farthest destination for a human spaceflight mission has been the Moon, and as of 2010 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 and Buzz Aldrin became the first people to set foot on the Moon. Six missions landed in total, numbered Apollo 11–17, excluding Apollo 13. Altogether twelve men walked on the Moon, 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.^[3]

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 period 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^[update], citizens from 33 nations (including space tourists) have flown in space aboard Soviet, American, Russian, and Chinese spacecraft.

Space programs

As of 2010, human spaceflight missions have been conducted by the former 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 India (ISRO), Ecuador (EXA), Japan (JAXA), Iran (ISA) and Malaysia (MNSA.

Countries which have human spaceflight agendas.

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

• Soyuz with Soyuz rocket—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—Cape Canaveral Air Force Station
• Voskhod—Baikonur Cosmodrome
• X-15—Edwards Air Force Base,^[4] (two internationally recognized suborbital flights in program)
• Gemini—Cape Canaveral Air Force Station
• Apollo—Kennedy Space Center (Apollo 7 at Cape Canaveral Air Force Station)
• Salyut space station—Baikonur Cosmodrome
• Almaz space station—Baikonur Cosmodrome (Almaz was a series of military space stations under cover of the civilian name Salyut)
• 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 six 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

Successfully executed manned programs are in bold.

Suborbital spaceflights are in italics.

Nation/Organization	Space agency	National term	First launched astronaut	Date	Spacecraft	Launcher
Soviet Union	Soviet space program (OKB-1 Design Bureau)	cosmonaut космонавт (Russian) kosmonavt	Yuri Gagarin	April 12, 1961	Vostok spacecraft	Vostok
United States	National Aeronautics and Space Administration (NASA)	astronaut	Alan Shepard	May 5, 1961	Mercury spacecraft	Redstone
China	China space program	宇航员 (Chinese) yǔhángyuán 航天员 (Chinese) hángtiānyuán	...	1973 (abandoned)	Shuguang 1	Long March 2A
China	China space program	宇航员 (Chinese) yǔhángyuán 航天员 (Chinese) hángtiānyuán	...	1981 (abandoned)	Piloted FSW	Long March 2
ESA	European Space Agency (ESA)	astronaut spationaut spationaute (French)	...	1992 (abandoned)	Hermes	Ariane V
Iraq[5]	...	رجل فضاء (Arabic) rajul faḍāʼ رائد فضاء (Arabic) rāʼib faḍāʼ ملاح فضائي (Arabic) mallāḥ faḍāʼiy	...	2001 (abandoned)	...	Tammouz 2 or 3
Japan	Japan Aerospace Exploration Agency (JAXA)	宇宙飛行士 (Japanese) uchūhikōshi	...	2003 (abandoned)	HOPE-X	H-II
China	China National Space Administration (CNSA)	taikonaut 太空人 (Chinese) tàikōng rén 宇航员 (Chinese) yǔhángyuán 航天员 (Chinese) hángtiānyuán	Yang Liwei	October 15, 2003	Shenzhou spacecraft	Long March 2F
India	Indian Space Research Organisation (ISRO)	vyomanaut gaganaut aakashagaami आकाशगामि:  (Sanskrit) brahmāndagaami ब्रह्मान्डगामि:  (Sanskrit) antarikshyaatri अन्तरिक्षयात्रि: (Sanskrit)	...	2016 (approved)[6]	Orbital Vehicle (OV)	GSLV Mk II
Iran	Iranian Space Agency (ISA)	فضانورد (Persian) faza navard	...	2019 (planned)[7][8]	ISA manned spacecraft	...
ESA	European Space Agency (ESA)	astronaut spationaut spationaute (French)	...	2020 (approved conceptually but full development not begun)[9][10][11][12]	ARV phase-2 (may be changed to CSTS)	Ariane V
Japan	Japan Aerospace Exploration Agency (JAXA)	宇宙飛行士 (Japanese) uchūhikōshi	...	2025 (planned)	HTV-based spacecraft	H-IIB
Romania	Romanian Cosmonautics and Aeronautics Association (ARCASPACE)	astronaut astronaut (Romanian)	...	TBA (approved)	Stabilo-mission8	ARCASPACE air-balloon

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.

Medical issues

Effects of microgravity

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.^[13]

In a weightless environment, astronauts put almost no weight on the back muscles or leg muscles used for standing up. Those muscles then start to weaken and eventually get smaller. If there is an emergency at landing, the loss of muscles, and consequently the loss of strength can be a serious problem. Sometimes, astronauts can lose up to 25% of their muscle mass on long term flights. When they get back to ground, they will be considerably weakened and will be out of action for a while.

Astronauts experiencing weightlessness will often lose their orientation, get motion sickness, and lose their sense of direction as their bodies try to get used to a weightless environment. When they get back to Earth, or any other mass with gravity, they have to readjust to the gravity and may have problems standing up, focusing their gaze, walking and turning. Importantly, those body motor disturbances after changing from different gravities only get worse the longer the exposure to little gravity. These changes will affect operational activities including approach and landing, docking, remote manipulation, and emergencies that may happen while landing. This can be a major roadblock to mission success.

Radiation

Without proper shielding the crews of missions beyond low Earth orbit (LEO) might be at risk from high-energy protons emitted by solar flares. Lawrence Townsend of the University of Tennessee and others have studied the most powerful solar flare ever recorded. That flare was seen by the British astronomer Richard Carrington in September 1859. Radiation doses astronauts would receive from a Carrington-type flare could cause acute radiation sickness and possibly even death.^[14]

Another type of radiation, galactic cosmic rays, present further challenges to human spaceflight beyond LEO.^[15]

Radiation damage to the immune system

There is also some scientific concern that extended space flight might slow down the body’s ability to protect itself against diseases.^[16] Some of the problems are a weakened immune system and the activation of dormant viruses in the body. Radiation can cause both short and long term consequences to the bone marrow stem cells which create the blood and immune systems. Because the interior of a spacecraft is so small, a weakened immune system and more active viruses in the body can lead to a fast spread of infection.

Isolation

During long missions, astronauts are isolated and confined into small spaces. Depression, cabin fever and other psychological problems may result that impact crew safety and mission success.

Astronauts may not be able to quickly return to Earth or receive medical supplies, equipment or personnel if a medical emergency occurs. The astronauts may have to rely for long periods on their limited existing resources and medical advice from the ground.

Launch safety

Reentry safety

Reliability

Fatality risk

As of 2009^[update], 18 crew members have died during actual spaceflight missions (see table). Over 100 others have died in accidents during activity directly related to spaceflight missions or testing.

See also

Lists

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

References

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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