Tiangong 1

Temporarily crew-tended space laboratory module, serving as a ‘target vehicle’ for the perfection of orbital rendezvous and docking, as well as demonstrating short-term orbital living. A total of three expeditions, including an unmanned and two crewed missions, were made to the station during its 2-year orbital life.

A.k.a.: Target Vehicle. Type: Crew-tended space laboratory. Crew size: 3. Programme: Project 921-II.
Agency: CMSA. Primary contractor: CAST/CASC. Status: Deactivated. Launch: 2011-09-29. Designed life: 2 Years. Launch vehicle: CZ-2F. Launch complex: Jiuquan-SLS2.

Programme

History

“Space Laboratory” is not a term officially recognised by the international spaceflight community as a specific type of spacecraft, and should not be confused with the space module named ‘Spacelab’ that was developed by the European Space Agency (ESA) and flew onboard the Space Shuttle in the 1980s and 90s. Chinese official writings described the Space Laboratory as a temporarily-manned Earth-orbiting spacecraft, which can be visited and tended by astronauts on a short-term basis and fly in automated mode on a 300—400 km low-Earth orbit between visits.

According to some Chinese publications, the Space Laboratory is a crossover between conventional manned spacecraft vehicles (e.g. Apollo, Soyuz, Shenzhou, etc.) and more sophisticated multi-modular space stations (e.g. Mir and the International Space Station). Although a Space Laboratory may well carry some mission payloads for both manned and unmanned scientific researches and experiments, it’s main purpose is to serve as a technology demonstrator to develop the techniques and technologies required for building a ‘real’ space station.

Compared with previous space stations launched by Russia and the United States, Tiangong 1 is much smaller (8.5 t orbital mass), with a shorter operational life (2 years). It only carried 60 man-days worth of food and supplies, and cannot be resupplied. The spacecraft is single-module, and non-expandable, with only a single docking port for the visiting Shenzhou vehicle. However, it provided a prototype design for the core module of China’s future space station, as well as the resupply ship Tianzhou.

Launch Campaign

Tiangong 1 was delivered to the Jiuquan Satellite Launch Centre in late June 2011 for final checkout and fuelling. However, on 22 August, days before the scheduled launch of Tiangong 1, a scientific satellite Shijian 11-04 failed to enter its intended orbit due to a malfunction of its CZ-2C launcher rocket. The launch of Tiangong 1 was postponed so that a full examination could be carried out on the CZ-2F (T1) launcher to ensure no similar design flaw existed. As a result, the fuelled Tiangong 1 module was left inside the spacecraft hangar in the launch centre for a month.

Finally, on 29 September 2011, Tiangong 1 was launched from the Pad 921 atop the CZ-2F (T1) launch vehicle. About 9 and a half minutes into the flight, Tiangong 1 was separated from the launched rocket and entered its initial parking orbit. After two orbit elevation manoeuvres, Tiangong 1 entered a 360 km near circular orbit, where it was tested remotely by the ground control.

Orbital Life

During its two-year operational life, Tiangong 1 was visited by three Shenzhou missions, including the unmanned Shenzhou 8 mission, and the crewed Shenzhou 9 and 10 mission. The two crewed missions, each with a three-person crew including a female astronaut, each spent about 10 days aboard Tiangong 1 to experience short-term orbital living. During each expedition mission, the Shenzhou vehicle remained docked with the Space Laboratory module most of the time but demonstrated one more undocking and docking procedure with its crew onboard, using either manual or automatic method.

During the Shenzhou 10 mission in June 2013, China’s second female astronaut Wang Yaping gave a physics lesson to Chinese school students live from orbit through video link. More than 60 million students across the country were expected to watch the lecture. The 45-min lecture covered a range of subjects including Newton’s second law of motion, as well as a brief Q&A session.

Re-entry

Tiangong 1 was designed for an operational life span of two years. After the departure of the last crew in June 2013, the space module was put into a sleep mode to continue flying in orbit, in order to allow the ground control to collect data on the longevity of key components before the module is commanded to gradually re-enter the atmosphere. Tiangong 1 remained flying normally in orbit for another 2 years and 9 months after the final visit (or 1,630 days since launch).

On 21 March 2016, the China Manned Space Agency (CMSA) announced that the ground mission control had lost all telemetry and communications with Tiangong 1, leaving no ability to safely control its descent. On 14 September, the CMSA confirmed that Tiangong 1 had descended to a 370 km orbit, and was losing altitude at a rate of 100 m per day. The space module is expected to burn up during an uncontrolled atmospheric re-entry sometime in the second half of 2017.

During the press conference for the Tiangong 2 launch on 14 September 2016, the spokeswoman of the CMSA, Wu Ping, confirmed that Tiangong 1 was intact and operating on a 370 km orbit, with an orbital depletion rate of about 100 m daily. The space module is expected to burn up during an uncontrolled atmospheric re-entry sometime in late 2017.

Although the CMSA did not give a reason for the abrupt ending of the Tiangong 1 mission, it is understood that the mission had ended unexpectedly due to a dysfunctional battery charger, leaving the space module unable to recharge its batteries from its solar panels. Tiangong 1 has two four-panel solar wings attached to its service compartment, each about 3.1 m x 10 m in size. These can be rotated to obtain maximum solar insolation regardless of spacecraft attitude. Sun sensors between the panels measure the sunlight incidence angle which allows the panels to be automatically commanded to an optimum angle.

The space module also carries a number of silver-zinc batteries in its service module, which can provide emergency power for about 6 hours in case of failure of the solar arrays. However, without a functioning batter charger to recharge, these batteries eventually ran out. Without power supply, the space module lost all communications and telemetry transmissions with the earth, so the ground control could no longer to command the space module for a controlled re-entry.

Despite some concerns, the majority of the Tiangong 1 module would burn up during the atmospheric re-entry, though It is probable that some large pieces will survive re-entry and hit the Earth’s surface. While it is impossible to accurately predict the time and location of the re-entry, the likelihood of this taking place over a populated area is minimal.

Spacecraft Design

General Design

The space laboratory module is 10.4 m in length and 3.35 m in diameter, and has an orbital mass of 8,506 kg. The module consists of two cylinder-shape sections: a habitable Experimental Compartment with an internal space of 14.4 cubic metres (2.0 x 1.8 x 4.0 m), and an inhabitable Service Compartment that houses propulsion, power, life support, and communications systems. A pair of solar wings each with 4 solar panels are attached to the Service Compartment. Visiting astronauts can enter the Experimental Compartment via the 0.8m-diametre hatch of the docking port on the front end of the compartment.

The module is connected to the visiting Shenzhou spacecraft via an androgynous docking mechanism developed by the Shanghai Academy of Spaceflight Technology (SAST). The system is believed to be similar to the Russian APAS-75, consisting of a docking port, radio beacons, transponders, communication antenna, UHF radar, laser rangefinder, and electro-optical tracking system. The inside diameter of the docking port is about 0.8 m.

The Shenzhou spacecraft carrying the visiting astronauts will act as the ‘chasing’ spacecraft, while the Space Laboratory will act passively as the ‘target’. In order to dock successfully, the two spacecraft will need to have a relative velocity of less than 0.2 m/s and lateral deviation of fewer than 18 cm. The rendezvous docking can be controlled manually by the astronauts onboard the Shenzhou spacecraft, under the remote control from ground, or automatically by onboard computer.

Mission Payloads

While flying unpiloted between docking missions, Tiangong 1 can serve as a platform for a range of Earth observation and scientific research missions using its onboard mission payloads. Its mission payloads included:

Earth environmental monitoring – A hyperspectral imager (HSI) developed by the Changchun Institute of Optics, Fine Mechanics, and Physics (CIOMP) and the Shanghai Institute of Technical Physics (SITP) is carried in the non-habitable section of the spacecraft’s Experimental Compartment. The imager can collect image data simultaneously in multiple narrow, adjacent spectral bands to provide a wealth image data of the Earth surface.

Material science – The spacecraft also carries mission payload for crystal growth experiments. Images and video data of the experiments are transmitted to ground via the downlink.

Space environment – The spacecraft carries instruments to detect and analyse solar energetic particles, atmospheric chemistry and physics, and ionospheric disturbances.

Specifications

Orbit (km):....................380—400
Inclination (º):...............42.77
Length (m):....................10.4
Diameter (m):..................3.35
Solar panel span (m):..........18.4
Pressurised volume (m3):.......14
Orbital Mass (kg):.............8,506
Propellants:...................N2O4/MMH

Mission History

Date         Mission       Type               Crew             Launch Site    Launch Vehicle
------------------------------------------------------------------------------
2011-09-29   Tiangong 1    Space laboratory   None             Jiuquan        CZ-2F (T1)
2011-11-02   Shenzhou 8    Unmanned test      None             Jiuquan        CZ-2F (Y8)
2012-06-16   Shenzhou 9    Crewed             Jing Haipeng     Jiuquan        CZ-2F (Y9)
                                               Liu Wang
                                               Liu Yang
2013-06-11   Shenzhou 10   Crewed             Nie Haisheng     Jiuquan        CZ-2F (Y10)
                                               Zhang Xiaoguang
                                               Wang Yaping

Image Gallery

Chronology

1993 – Second 863 Space Expert Committee formed. The new space expert committee was tasked with the draft of the space station plan. Under the committee were three expert groups: Comprehensive, Space Station, and Heavy Launch Vehicle. The committee produced three proposals for developing the space station:

Proposal A: to first launch 20 t space laboratory modules using the proposed heavy-lift launch vehicle, followed by the launch of the 20-tonne-class space station;
Proposal B: to first launch 10 to 20 t space laboratory modules using a newly developed launch vehicle, followed by the launch of the 20-tonne-class space station using the proposed heavy-lift launch vehicle;
Proposal C: to first launch 8 t space laboratory modules using the CZ-2F launch vehicle, followed by the launch of the 20-tonne-class space station using the proposed heavy-lift launch vehicle;

A financial evaluation of the three proposals conducted by the Management School of the Beijing University of Aeronautics and Astronautics (BUAA) showed that Proposal A and C would have roughly same amount of cost, while Proposal B would have a slightly higher costs due to the requirement to develop a new launch vehicle with 10 to 20-tonne payload capacity. Proposal B would have the highest risk in development cost, while Proposal C would have the highest risk in development time. In addition, Proposal C would not allow the technologies for the future space station to be fully validated since the 8-tonne-class space laboratory module has much less capacity for crew occupation and space applications payloads compared with the 20-tonne-class space station.


1996 – Space station plan signed off. The plan for developing space laboratories and space station was signed off.


2005 February – Phase-II of Project 921 approved. The objective of this phase of the programme was to develop advanced space flight techniques including extra-vehicular activity (EVA) and orbital rendezvous docking in support of the future space station.


2005 October – Human spaceflight included in the national science and technology development plan. The State Council published the National Outline on Medium- and Long-Term Science and Technology Development (2006—2020), which put human space flight and lunar exploration as one of the China’s 16 key science and technology projects over the next fifteen years, effectively enshrining the space station programme into national strategy. Over the next three years, the PLA General Armaments Department (GAD) that oversees China’s manned space programme worked with the space industry and other research institutions to draw up a plan for the implementation of the space station construction.


2010 September – Space station programme approved. Chinese official writings described the objectives of the space station programme as “to build an operational manned space station in LEO around 2020, allowing the grasp of long-term inhabitation of space, acquiring the capability to conduct long-duration, man-tended scientific and technological experiments in orbit, and enabling comprehensive exploration and utilisation of space resources”.


2011 July – Tiangong 1 launch campaign began. The Tiangong 1 space laboratory, also known as the ‘Target Vehicle’ was delivered by air to the Jiuquan Satellite Launch Centre. The CZ-2F (T1) launch vehicle also arrived at the launch centre shortly after.


2011 August 26 – Shenzhou 8 launch campaign began. The Shenzhou 8 spacecraft vehicle was delivered to Jiuquan by air.


2011 September 1 – Tiangong 1 launch delayed.  A CZ-2C launch vehicle that lifted off from the Jiuquan launch centre on 18 August failed to place its payload, an engineering experiment satellite named Shijian 11-04, into its intended orbit due to a second-stage engine malfunction. A spoke person of the China Manned Space Programme confirmed that the launch schedule for Tiangong 1 “had been adjusted”. He emphasized that the preparation for China’s first rendezvous docking was still progressing smoothly. However, following the unsuccessful launch of the Shijian 11-04, the mission planners had decided to postpone the Tiangong 1 launch as a precaution to allow engineers time to investigate the reasons of the failure.


2011 September 29 — Tiangong 1. Following nearly a month delay, Tiangong 1 was launched atop the CZ-2F (T1) launch vehicle from Pad 921 at the Jiuquan Satellite Launch Centre at 21:16 CST. The space module was primarily intended as a target vehicle to perfect orbital rendezvous docking, in order to pave way for the construction of the future permanently-manned space station.


2011 November 1 – Shenzhou 8 mission. Shenzhou 8 was launched atop the CZ-2F (Y8) launcher rocket from Jiuquan at 05:58 CST. After five orbit elevation manoeuvres in 44 hours, the spacecraft vehicle reached a position about 52 km away from Tiangong 1. The first docking was scheduled to take place while the two vehicles flew over the Chinese territory, where ground-based tracking stations could provide intensive tracking and telemetry support. The time of the docking was in midnight local time in order to avoid the interruptions of sun flares to the spacecraft’s docking and tracking systems. The two vehicles established an initial contact at 01:28 CST on 2 November, and the hard mate was established at 01:36 CST, marking the success in China’s first ever orbital rendezvous docking. On 14 November, Shenzhou 8 undocked with Tiangong 1 and retreated to a position 140 m away under the ground control, and then performed another automated docking with Tiangong 1. The vehicle left Tiangong 1 and landed on 17 November.


2012 April-June – Shenzhou 9 launch campaign began. The Shenzhou 9 vehicle was delivered to Jiuquan for initial preparation. The CZ-2F (Y9) launch vehicle arrived at the launch centre in early May. The fuelling the Shenzhou 9 vehicle was completed on 29 May. The launch vehicle and spacecraft stack was rolled out to the launch pad on 9 June.


2012 June 16 – Shenzhou 9 mission. The Shenzhou 9 spacecraft vehicle carrying Jin Haipeng (mission commander), Liu Wang (flight engineer and pilot), and China’s first female astronaut Liu Yang was launched atop the CZ-2F (Y9) launch vehicle from Pad 921 at the Jiuquan launch centre at 18:37 CST. In the first 40 hours of the flight, Shenzhou 9 made five orbit elevation manoeuvres to match the orbit of Tiangong 1. It reached a position about 52 km away from Tiangong 1 in the mid-day of 18 June. The two vehicles made the first contact at 14:07 CST on 18 June. Three hours after the docking, the three astronauts entered Tiangong 1 for the first time. On 24 June, Shenzhou 9 undockced with Tiangong 1 to perform a manual docking. The vehicle undocked with Tiangong 1 at 11:08 CST and retreated in the automated mode to a hold point 400 m away, and then closed in to Tiangong 1 again under auto pilot. When the vehicle paused at the 140 m hold point, astronaut Liu Wang switched on manual flight control and took over the control of the spacecraft. Initial contact and capture occurred at about 12:48 CST. On 28 June, Shenzhou 9 carrying the crew undocked with Tiangong 1 at 09:22 CST. The vehicle first retreated to a hold point 140 m away from Tiangong 1 under the manual control of astronaut Liu Wang, and then switched to automated guidance mode and continued retreating to a 5 km hold point. It then repeated the automated rendezvous procedure and closed in to Tiangong 1 again until the 140 m hold point, before eventually departing for re-entry. The re-entry sequence was initiated at 09:17 CST on 29 June. The re-entry capsule carrying the crew touched down in the at 10:03 CST. Strong wind caused the capsule to land 16 km off its targeted landing spot, but the search and rescue helicopters quickly reached the landing spot.


2013 March-June – Shenzhou 10 launch campaign began. The Shenzhou 10 spacecraft vehicle completed its initial testing in the Beijing Space City and was airlifted to the Jiuquan Satellite Launch Centre. The CZ-2F (Y10) launch vehicle arrived at the launch centre by railway on 2 May. The fuelling of the spacecraft’s service and re-entry modules was completed on 23 May. The crew was flown to the launch centre on 3 June. The rollout of the CZ-2F / Shenzhou 10 stack occurred at 09:00 CST on 3 June.


2013 June 11 – Shenzhou 10 mission. The Shenzhou 10 vehicle carrying Nie Haisheng (mission commander and pilot), Zhang Xiaoguang (flight engineer), and female astronaut Wang Yaping (mission specialist) lifted off atop the CZ-2F (Y10) launch vehicle from Pad 921 at the Jiuquan launch centre at 17:38 CST. After several orbit elevation manoeuvres, Shenzhou 10 entered the docking orbit. At 10:48 CST on 13 June, the spacecraft initiated its rendezvous docking sequence. Commander Nie Haisheng and Flight Engineer Zhang Xiaoguang were on standby to take over the control should the automated docking fail. The two spacecraft vehicles made first contact at 13:11 CST. On 20 June, Astronaut Wang Yaping gave a lesson to Chinese school students on live television from orbit, the first of its kind in China. More than 60 million students across the country were expected to watch the lecture. The 45-minute lecture covered a range of subjects including Newton’s second law of motion, as well as a brief Q&A session. On 23 June, Shenzhou 10 undocked with Tiangong 1 to perform a manual docking. Undocking occurred at 08:26 CST under the manual control of Nie Haisheng. The spacecraft vehicle retreated to a hold position, where it’s status was examined by the ground control, before closed in to Tiangong 1 again under manual control. The two spacecraft vehicles made initial contact at 10:00 CST. On 25 June, the crew exited from Tiangong 1 and sealed the hatch in the docking port at 05:07 CST. Shenzhou 10 then undocked with Tiangong 1 for the last time. Shortly after the undocking, Shenzhou10 completed a 180° manoeuvre around Tiangong 1, from a plus V-bar position to a minus V-bar position. The whole manoeuvre took about 2 hours to complete. The re-entry capsule of Shenzhou 10 carrying the three crew members safely landed in Inner Mongolia at 08:07 CST on 26 June.


2016 March 21 – Loss of Tiangong 1 telemetry. Tiangong 1 was designed for an operational life span of two year. After the departure of the last crew in June 2013, the space module was put into a sleep mode to continue flying in orbit, in order to allow the ground control to collect data on the longevity of key components before the module is commanded to gradually re-enter the atmosphere. Tiangong 1 remained flying normally in orbit for another 2 years and 9 months after the final visit (or 1,630 days since launch). On 21 March 2016, the China Manned Space Agency announced that all telemetry on the space module had failed, leaving no ability to safely control its descent. The space module is expected to re-enter the atmosphere in the coming months.


References

Leave a Reply