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Tiangong-1 () was China's first prototype
space station A space station is a spacecraft capable of supporting a human crew in orbit for an extended period of time, and is therefore a type of space habitat. It lacks major propulsion or landing systems. An orbital station or an orbital space station i ...
. It orbited Earth from September 2011 to April 2018, serving as both a crewed laboratory and an experimental testbed to demonstrate
orbital rendezvous A space rendezvous () is a set of orbital maneuvers during which two spacecraft, one of which is often a space station, arrive at the same orbit and approach to a very close distance (e.g. within visual contact). Rendezvous requires a precise ma ...
and docking capabilities during its two years of active operational life. Launched uncrewed aboard a Long March 2F launch vehicle on 29 September 2011, it was the first operational component of the Tiangong program, which launched a larger, modular station into orbit in 2021. Tiangong-1 was initially projected to be deorbited in 2013,"China to launch module for future space station"
PhysOrg 28 September 2011 Retrieved 10 March 2013
to be replaced over the following decade by the larger Tiangong-2 and Tiangong-3 space stations, but it orbited until 2 April 2018. Tiangong-1 was visited by a series of Shenzhou spacecraft during its two-year operational lifetime. The first of these, the uncrewed Shenzhou 8, successfully docked with the module in November 2011, while the crewed Shenzhou 9 mission docked in June 2012. A third and final mission to Tiangong-1, the crewed Shenzhou 10, docked in June 2013. The crewed missions to Tiangong-1 were notable for including China's first
female astronauts The following is a list of women who have traveled into space, sorted by date of first flight. This list includes Russian cosmonauts, who were the first women in outer space. Valentina Tereshkova became the first woman to go to space in 1963, ...
, Liu Yang and Wang Yaping. On 21 March 2016, after a lifespan extended by two years, the China Manned Space Engineering Office announced that Tiangong-1 had officially ended its service. They went on to state that the telemetry link with Tiangong-1 had been lost. A couple of months later, amateur satellite trackers watching Tiangong-1 found that China's space agency had lost control of the station. In September 2016, after conceding they had lost control over the station, officials speculated that the station would re-enter and burn up in the atmosphere late in 2017. According to the China Manned Space Engineering Office, Tiangong-1 started reentry over the
southern Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
, northwest of Tahiti, on 2 April 2018 at 00:16 UTC.


Design and development

The
China National Space Administration China National Space Administration (CNSA; ) is the government agency of the People's Republic of China that is responsible for civil space administration and international space cooperation, including organizing or leading foreign exchanges ...
(CNSA) designed Tiangong-1 as an "space-laboratory module", capable of supporting the docking of crewed and autonomous spacecraft. In 2008, the China Manned Space Engineering Office (CMSEO) released a brief description of Tiangong-1, along with its larger successor modules, Tiangong-2 and Tiangong-3. A model of the space station was revealed in the
Chinese Lunar New Year Chinese New Year is the festival that celebrates the beginning of a new year on the traditional lunisolar and solar Chinese calendar. In Chinese and other East Asian cultures, the festival is commonly referred to as the Spring Festival () as ...
celebration program on CCTV on 25 January 2009. On 29 September 2008, Zhang Jianqi (), vice-director of the CMSEO, declared in an interview with
China Central Television China Central Television (CCTV) is a Chinese state- and political party-owned broadcaster controlled by the Chinese Communist Party (CCP). Its 50 different channels broadcast a variety of programing to more than one billion viewers in six lan ...
(CCTV) that Tiangong-1 would be launched in 2010 or 2011. Xinhua News Agency later stated that Tiangong-1 would be launched in late 2010, and declared that the renovation of ground equipment was in progress. However, the launch did not ultimately take place until 2011. By mid-2011, the construction of Tiangong-1 was complete, and its systems and thermal properties were undergoing testing. Testing was also conducted on the Long March 2F launch vehicle on which Tiangong-1 would be launched. Technicians undertook particularly extensive safety tests on the launch vehicle due to the recent launch failure of a Long March 2C launch vehicle.


Structure

Tiangong-1 had a pressurised habitable volume of approximately , and used passive APAS-type docking connectors. Structurally, Tiangong-1 was divided into two primary sections: a resource module, which mounted its
solar panel A solar cell panel, solar electric panel, photo-voltaic (PV) module, PV panel or solar panel is an assembly of photovoltaic solar cells mounted in a (usually rectangular) frame, and a neatly organised collection of PV panels is called a photo ...
s and propulsion systems, and a larger, habitable experimental module.


Onboard facilities

Tiangong-1's experimental module was equipped with exercise gear and two sleep stations. The interior walls of the spacecraft had a two-color paint scheme – one color representative of the ground, and the other representative of the sky. This was intended to help the astronauts maintain their orientation in zero gravity. High-resolution interior cameras allowed crewed missions to be closely monitored from the ground, and the two sleep stations had individual lighting controls."Living on Tiangong"
SpaceDaily 25 October 2011 Retrieved 29 October 2011
Toilet facilities and cooking equipment for the crewed missions were provided by the docked Shenzhou (spacecraft), rather than being integrated into the Tiangong module itself. Similarly, one member of the module's three-person crew slept in the Shenzhou spacecraft, preventing overcrowding.


Mission profile


Background

Tiangong-1 was originally intended to be launched in August 2011, and was delivered to the Jiuquan Satellite Launch Center on 23 July 2011, successfully passing a launch rehearsal test on 17 August 2011. However, following the failed launch of a Long March 2C launch vehicle in August 2011, the launch was postponed. Following an investigation into the August 2011 launch failure, Tiangong-1's launch was rescheduled for late September 2011, partly to coincide with the Chinese National Day on 1 October 2011.


Launch

On 20 September 2011, the spacecraft was again rolled out to Pad 1 of the South Launch Site at Jiuquan Satellite Launch Center in preparation for the rescheduled launch attempt. The launch occurred at 13:16 UTC on 29 September 2011, successfully placing Tiangong-1 into low Earth orbit. Chinese television broadcast the launch animation accompanied by an instrumental version of the American patriotic song '' America the Beautiful'', a choice of music for which it later offered no explanation.


Orbital transfers and testing

On 30 September 2011, Tiangong-1 completed the second of two
orbital transfer In spaceflight, an orbital maneuver (otherwise known as a burn) is the use of propulsion systems to change the orbit of a spacecraft. For spacecraft far from Earth (for example those in orbits around the Sun) an orbital maneuver is called a ' ...
maneuvers, reaching an apogee altitude of ."天宫一号成功完成二次变轨" (in Chinese)
''
People's Daily The ''People's Daily'' () is the official newspaper of the Central Committee of the Chinese Communist Party (CCP). The newspaper provides direct information on the policies and viewpoints of the CCP. In addition to its main Chinese-language ...
'' 1 October 2011 Retrieved 21 November 2011
This was the precursor to a week-long program of orbital testing, conducted from the
Beijing Aerospace Command and Control Center Beijing Aerospace Flight Control Center (), formerly known as Beijing Aerospace Command and Control Center (; BACCC or BACC), is a command center for the Chinese space program which includes the Shenzhou missions, and is located in a suburb nor ...
, to prepare the module for future orbital docking operations. On 10 October 2011, Tiangong-1 released its first orbital photo, showing a view of its outer hull and satellite relay antenna.


Autonomous orbital docking

The uncrewed Shenzhou 8 mission successfully docked with Tiangong-1 on 2 November 2011 UTC, marking China's first orbital docking."Chinese spacecraft dock in orbit"
BBC News 2 November 2011 Retrieved 15 June 2013
Shenzhou 8 undocked from Tiangong-1 on 14 November 2011, before successfully completing a second rendezvous and docking, thus testing the reusability of the docking system."China completes second space docking"
Agence France Presse via Google 14 November 2011 Retrieved 15 November 2011

Xinhua 7 November 2011 Retrieved 15 June 2013
Shenzhou 8 deorbited on 17 November 2011, and landed intact in
Siziwang Banner Dorbod (Siziwang) Banner ( mn, , , ; ) is a banner (county equivalent) in Ulanqab, Inner Mongolia, China, bordering Mongolia's Dornogovi Province to the northwest. It is located about north of Hohhot, the capital of Inner Mongolia. The banner ...
in Inner Mongolia. After the mission, the CNSA reported that Tiangong-1's systems were in optimal condition.


Crewed missions


Preparations

In December 2011, the Tiangong-1 module began automated internal checks for toxic gas, to ensure that its interior would be safe for astronauts to enter. In January 2012, reports emerged in British publication Spaceflight alleging that the American Boeing X-37B robotic spaceplane was shadowing Tiangong-1 for surveillance purposes. However, former United States Air Force orbital analyst Brian Weeden later refuted this claim, emphasizing that the X-37B occupied a 100 degree right ascension offset orbit from Tiangong-1, and would not be able to closely observe the module as they would only pass each other twice an orbit at a closing speed of 7 km/s.


Shenzhou 9 (Expedition 1)

In March 2012, it was reported that China had finished the initial crew selection for the Shenzhou 9 mission. Niu Hongguang, the deputy chief commander of the China Manned Space Engineering Office, stated that Shenzhou 9 would dock with Tiangong-1 before August 2012. The Shenzhou 9 spacecraft was delivered to Jiuquan Satellite Launch Center for launch preparations on 9 April 2012, while its Long March 2F launch vehicle arrived a month later on 9 May 2012. Shenzhou 9 launched successfully on 16 June 2012, carrying with it China's first female astronaut, Liu Yang."China sends its first female astronaut into space"
The Daily Telegraph 16 June 2012 Retrieved 4 November 2013
The spacecraft docked with Tiangong-1 on 18 June 2012 at 06:07 UTC (14:07 Beijing time)."Shenzhou-9 docks with Tiangong-1"
BBC 18 June 2012 Retrieved 4 November 2013.
After about three hours, when the air pressures inside the two vessels were equalized, mission commander Jing Haipeng entered Tiangong-1. The first docking was entirely computer-controlled, without input from the three astronauts; a second, crew-guided docking was successfully conducted on 24 June 2012 at 20:42 UTC (12:42 Beijing time)."Video: China's first manual space docking"
People's Daily 24 June 2012 Retrieved 4 November 2013
Shenzhou 9 landed safely in Inner Mongolia on 29 June 2012. In August 2012, Shenzhou 9's crew travelled to Hong Kong to discuss their mission with university students.


Shenzhou 10 (Expedition 2)

The crewed Shenzhou 10 spacecraft, the final Shenzhou mission to rendezvous with Tiangong-1 before its deorbit, was launched on 11 June 2013. The launch of Shenzhou 10 was originally planned for earlier in the year, but was delayed to allow the mission to incorporate more complex scientific experiments. The mission's crew included China's second female astronaut, Wang Yaping. Shenzhou 10 docked successfully with Tiangong-1 on 13 June 2013. On 15 June 2013, the Shenzhou 10 crew completed China's first orbital maintenance operation, replacing Tiangong-1's interior cladding. Additional maintenance work was conducted on the space station's seal rings. On 20 June 2013, Wang Yaping delivered a remote video lecture from orbit to students across China, demonstrating physics in
microgravity The term micro-g environment (also μg, often referred to by the term microgravity) is more or less synonymous with the terms ''weightlessness'' and ''zero-g'', but emphasising that g-forces are never exactly zero—just very small (on the I ...
with her colleagues. On 24 June 2013,
CPC general secretary The general secretary of the Chinese Communist Party () is the head of the Chinese Communist Party (CCP), the sole ruling party of the People's Republic of China (PRC). Since 1989, the CCP general secretary has been the paramount leader ...
Xi Jinping contacted the astronauts via remote video link to congratulate them. After a series of successful docking tests, Shenzhou 10 undocked and returned safely to Earth on 26 June 2013. With a duration of 15 days, Shenzhou 10 was China's longest crewed space mission, until Shenzhou 11's 30-day mission to Tiangong-2 in 2016.


Post-mission

The Tiangong-1 was launched in September 2011, with an intended service span of two years. After the last crew departed the module in June 2013, it was put into sleep mode. It was intended that it would remain in orbit for some time, allowing China to collect data on the longevity of key components before being commanded to gradually re-enter the atmosphere. The
Permanent mission A diplomatic mission or foreign mission is a group of people from a state or organization present in another state to represent the sending state or organization officially in the receiving or host state. In practice, the phrase usually deno ...
of China to the United Nations ( Vienna) informed the United Nations Committee on the Peaceful Uses of Outer Space that communication with Tiangong-1 had ceased functioning on 16 March 2016. One week later on 21 March 2016, the China Manned Space Engineering Office announced that they had officially disabled data service and ended the mission. According to the office, the space laboratory was under continued and close monitoring until it finally burned up in the Earth's atmosphere during an uncontrolled re-entry.


Re-entry

The orbit of Tiangong-1 decayed gradually, and the space laboratory was predicted to be destroyed upon re-entry into Earth's atmosphere. At the request of China and the United Nations Office for Outer Space Affairs (UNOOSA), the Inter-Agency Space Debris Coordination Committee (IADC), led by the
European Space Agency , owners = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre , seal = File:ESA emblem seal.png , seal_size = 130px , image = Views in the Main Control Room (1205 ...
(ESA), conducted an international campaign to monitor the re-entry of Tiangong-1. ESA's Space Debris Office in
Darmstadt Darmstadt () is a city in the States of Germany, state of Hesse in Germany, located in the southern part of the Frankfurt Rhine Main Area, Rhine-Main-Area (Frankfurt Metropolitan Region). Darmstadt has around 160,000 inhabitants, making it th ...
, Germany hosted and administered the campaign, with participation from other space agencies and organizations including the
China National Space Administration China National Space Administration (CNSA; ) is the government agency of the People's Republic of China that is responsible for civil space administration and international space cooperation, including organizing or leading foreign exchanges ...
(CNSA), the
Indian Space Research Organisation The Indian Space Research Organisation (ISRO; ) is the national space agency of India, headquartered in Bengaluru. It operates under the Department of Space (DOS) which is directly overseen by the Prime Minister of India, while the Chairman ...
(ISRO), the
Japan Aerospace Exploration Agency The is the Japanese national air and space agency. Through the merger of three previously independent organizations, JAXA was formed on 1 October 2003. JAXA is responsible for research, technology development and launch of satellites into orb ...
(JAXA), the Korea Aerospace Research Institute (KARI), and Roscosmos of Russia. The IADC predicted that Tiangong-1 would break up during re-entry, but that parts of the station would survive and fall to the Earth's surface, potentially falling across an area thousands of kilometres long and tens of kilometres wide. However, because most of the re-entry area was ocean or uninhabited land, the IADC stated that the odds of a person being hit by falling debris to be "10 million times smaller than the yearly chance of being hit by lightning". The IADC's final prediction before re-entry was that Tiangong-1 would re-enter at around 01:00 UTC on 2 April 2018, plus or minus 2 hours, falling somewhere on Earth between 42.8° North and 42.8° South latitudes, with the most likely re-entry sites being at the north and south extremes of that range. This is because an inclined orbit has the smallest north-south speed at the extreme latitudes, and the greatest north-south speed near the
equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can als ...
. Independently, the non-profit Aerospace Corporation's Center for Orbital and Re-entry Debris Studies (CORDS) predicted that Tiangong-1 would most likely re-enter the atmosphere around 00:30 UTC on 2 April 2018, plus or minus 1.7 hours. CORDS scientists also predicted that it would re-enter somewhere between the 42.7° North and 42.7° South latitudes, a range that covered two-thirds of the Earth's surface, with a high likelihood of an ocean landing of whatever did not burn up during re-entry. They predicted that if any parts of the station survived re-entry, the small amount of debris would impact the ground over an area a few hundred square kilometers in size. The final prediction of likely areas for debris impact covered southern South America, Africa, the Middle East, and central Asia. However, even in those high-probability areas, they still estimated the odds of a specific person being hit by debris to be "about one million times smaller than the odds of winning the Powerball jackpot". Tiangong-1 reentered the Earth's atmosphere at approximately 00:16 UTC on 2 April 2018 over the South Pacific Ocean at . According to Chinese state news agency Xinhua, the station mostly burnt up upon re-entry. A fisherman from the nearby island of
Maupiti Maupiti is an island in the western Leeward Islands in French Polynesia. It is the westernmost volcanic high island in the archipelago, northwest of Tahiti and west of Bora Bora. It has a population of 1,286 people. The largest town is Vaiea. ...
was able to witness the event. It was the largest spacecraft to re-enter the atmosphere since Fobos-Grunt in January 2012. This was about from Point Nemo, a location often used as a
spacecraft cemetery The spacecraft cemetery, known more formally as the South Pacific Ocean(ic) Uninhabited Area, is a region in the southern Pacific Ocean east of New Zealand, where spacecraft that have reached the end of their usefulness are routinely crashed. Th ...
to crash defunct satellites. As the spacecraft made an uncontrolled reentry, this was an unintended coincidence.


Program developments

Tiangong-1 was designed as a test bed for key technologies later used on another test station called Tiangong-2, which was launched on 15 September 2016. Both experimental space stations were short-lived and meant to test technologies and systems for the Tiangong space station, which is planned to be assembled from 2021 to 2022. The design of Tianzhou, an automated cargo spacecraft intended to resupply the Tiangong space station, is based on Tiangong-1.


See also

* Agena target vehicle * Chinese space program *
Chinese women in space In 2012, China became the third nation to send women into space with its own space program, after the Soviet Union/Russia and the United States, 49 years after the first female cosmonaut, Valentina Tereshkova. History Following the successful ...
* International Space Station * List of space stations * Salyut 1 * Skylab


References


External links

* {{Orbit, satcat, 37820, hide 2011 in China Chinese space stations Space stations Spacecraft launched in 2011 Spacecraft which reentered in 2018 Tiangong program Satellites in low Earth orbit