By David Xia SinoDefence.com China’s space station plan emerged in the mid-1980s in the wake of a global race to establish...
By David Xia
SinoDefence.com
China’s space
station plan emerged in the mid-1980s in the wake of a global race to establish
permanent human presence in space. The Soviet Union had already launched a
number of Salyut/Almaz space stations and began to assemble a new multi-module
station Mir. The United States government unveiled its ambitious plan to build
Space Station Freedom. Japan and Europe also announced their plans to send
human into space. Chinese space professionals believed that the country should
have its own space station to avoid falling behind.
The goal of
constructing an Earth-orbiting manned space station was set very early on in
China’s manned space planning. Under Programme 863 (state high-tech R&D
initiative), two expert groups were set up in February 1987 to draw up designs
for the crew transportation system and manned space station respectively. While
the choice for the crew transportation system between space shuttle and manned
capsule sparked heated debates within the space community, having a space
station as the ultimate goal for the manned programme was never a point of
contention.
By 1991, the
Chinese space industry had formulated a thirty-year plan to develop China’s
human space flight technology in three phases: to send human into space aboard
manned capsule in the first phase, to develop advanced spaceflight techniques
including EVA and rendezvous docking and to launch 8 tonne temporarily
man-tended space laboratories in the second phase, and to eventually build a 20
tonne manned space station in the third phase by 2020.
In September
1992, the Chinese leadership gave go-ahead to the initial phase of the manned
programme, with the aim to send human into orbit aboard a manned capsule – the
first step towards establishing human Chinese presence in space. The programme
came to a conclusion in 2005 after having successfully launched four unmanned
Shenzhou test flights and two crewed missions, making China the third country
in the world to have the ability to send human into space independently.
In February
2005, the Chinese leadership approved the follow-up missions in the second
phase of the manned programme, with the objective to develop advanced space
flight techniques including extra-vehicular activity (EVA) and orbital
rendezvous docking in support of the future space station programme. The first
of these missions Shenzhou 7 was launched in 2008, which saw two Chinese
astronauts performing a 20-minute spacewalk.
In October 2005,
the State Council (central government) 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 various relevant institutions to
draw up a plan for the implementation of the space station programme.
The Chinese
leadership officially approved the manned space station plan in September 2010.
Chinese official writings described the objectives of the space station
programme as “to build an operational manned space station in the low Earth
orbit (LEO) around 2020, allowing the grasp of long-duration 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”.
The original
Project 921 writings called for the construction of a single-module station of
20 tonne orbital mass, essentially an enlarged space laboratory roughly
comparable in size and capability to second-generation Salyut stations. By the
time of the draft plan in 2010 this has evolved into a three-module
configuration with a total orbital mass of 60 tonnes. In addition to serve as a
scientific research facility in the low Earth orbit, Chinese space
professionals also viewed the station as a platform to perfect and demonstrate
long-duration life support, environment control, and resources recycle
technologies required for future Chinese crewed deep space exploration missions
including a temporarily-manned lunar base.
Early Tiangong Concept
An early concept
of the Tiangong Space Station
In October 2013,
the China Manned Space Agency (CMSA) announced the naming of the Chinese space
station. The station is named Tiangong (TG), the same name used by the two
space laboratories launched during the second phase of the manned space
programme but without a design number. The word Tiangong could be roughly
translated as “Heavenly Palace” in English. The core module is named Tianhe
(TH). The two laboratory modules are named Wentian (WT) and Xuntian (XT)
respectively. The resupply cargo spacecraft is named Tianzhou (TZ).
Later Tiangong
Space Station concept
Design
Tiangong is a third-generation modular space station, similar to the Russian Mir and the International Space Station but smaller in size. The space station in its basic configuration consists of a core module and two laboratory modules permanently docked together in a T-shape structure. Each of the three modules weighs about 20 tonnes. Together with two Shenzhou crew vehicles and a cargo resupply ship, the station will have a total mass of over 90 tonnes.
The three
modules will be launched atop the Chang Zheng-5B launcher from the Hainan
Satellite Launch Centre between 2018 and 2022. The station will station
operates in a 42—43° inclined orbit 340—450 km above Earth, with a designed
life of 10 years. If the International Space Station programme is to be retired
in 2020 as currently scheduled, by the time it is fully assembled Tiangong may
be the only operational space station in Earth orbit.
Between its
three modules, the space station provides a total useable volume of 90 cubic
metres for its crew. It is designed to support a three-man crew to live and
work onboard continuously, though it can also operate with two astronauts only
or completely autonomously. During its construction phase, the station will only
be visited intermittently and remain unoccupied between visits. Once fully
operational, the station will be continuously occupied. The station will also
require at least one cargo resupply mission every 12 months to remain
operational.
Modules
Tianhe Core
Module
The core module,
named Tianhe (“Heavenly Harmony”), is the backbone of the Tiangong space
station, providing the main living quarters and also serving as the primary
control element for the entire space station. The module is divided into three
sections: an uninhabitable service compartment at rear, a pressurised living
compartment in the middle, and a docking hub which also serves as an airlock at
front. The module has a total of five passive APAS-type docking ports, four
located on the docking hub at front and one on the rear end of the module.
The docking hub
located at the forward end of the core module provides four docking ports. The
two lateral docking ports are used as permanent attachment points for the two
laboratory modules. The docking ports on the axis and Earth-facing directions
are used for temporary docking of visiting Shenzhou crew vehicles. On the side
of the hub facing away from the Earth a sealable hatch allows EVA astronauts to
exit and re-enter the station. Externally the docking hub mounts a pair of
solar panel wings and docking radar antennas and optical sensors.
The docking hub
also doubles as an airlock to host EVAs, with a hatch located on the side
facing away from the Earth to allow spacewalking astronauts to exit and
re-enter the station. Spacesuits and other equipment will also be stored inside
the hub. The docking hub provides the only EVA airlock for the core module
during the initial construction phase. A permanent EVA airlock compartment will
become available once the Wentian laboratory module is in place, after which
the docking hub will only serves as a backup airlock.
The
unpressurised service compartment accommodates the main engines, propellant
tanks, power system, and communications system. A fifth docking port located at
the rear end of the module is used for temporary docking of the Tianzhou
resupply ship, though it can also be used as a backup docking point for the
Shenzhou crew vehicle. A pressurised internal tunnel links the docking port
through the service compartment to the living compartment to allow transfer of
cargo and crew.
Wentian
Laboratory Module
The first
laboratory module, named Wentian (“Exploring the Sky”), will be designed and
built by CAST in Beijing. The module divided into three sections: a fully
pressurised working compartment at front, an airlock compartment in the middle,
and an unpressurised service compartment at rear. The module is attached to the
starboard side of the core module’s docking hub through an active APAS-type
docking port at its front end. A pair of solar panel wings is mounted on a
large boom with its centre attached to the rear end of the module.
The working
compartment provides space for scientific and technological experiments, and is
also used as a storage space for consumables and supplies used by the crew. The
module is fitted with a secondary station control system as a backup to the
main control system in the core module. The primary application payload onboard
the Wentian module is a suite of Earth-observation instruments.
Xuntian
Laboratory Module
The second
laboratory module, named Xuntian (“Cruising the Sky”), will be designed and
built by SAST in Shanghai. The module is also divided into three sections: a
fully pressurised working compartment at front, an unpressurised application
compartment in the middle, and an unpressurised service compartment at rear. It
is attached to the port side of the core module’s docking hub through an active
APAS-type docking port at its front end. A pair of solar panel wings is mounted
on a large boom with its centre attached to the rear end of the module. The
primary application system onboard the Wentian module is a space telescope
mounted in the unpressurised application compartment, facing away from the
Earth.
The basic
three-module configuration of Tiangong
The expanded
six-module configuration of Tiangong
Spacecraft
Systems
Power to the
station is provided by an array of solar cells consisting of a pair of solar
panel wings attached to the core module providing power supply during the
initial flight demonstration and construction phase, and four large solar
panels wings on the two laboratory modules as the main power source. The two
solar panel wings on the core module are one-axis steerable, whereas the solar
panel wings on the laboratory modules are two-axis steerable to track the Sun.
The power management and distribution subsystem operates at a primary bus
voltage of 100 volts.
There are two
flight control systems providing most station control functions: a primary
system on the core module and a backup system on the Xuntian module. The
Tiangong space station will adopt an electrically-powered propulsion system
using ion thrusters to reduce the amount of propellants being consumed for
station keeping. All three modules of the space station are equipped with
digital wireless communications. Information sharing and management is through
three networks for spacecraft systems, communications, and payloads.
Communication with the ground is via unified S-band (USB) links either directly
to ground stations or through Tian Lian geostationary data relay satellites.
The space station is equipped with two robotic arms. The primary arm on the core module is developed by CAST and has a load capacity of 25 tonnes. The secondary arm on the Wentian laboratory module is developed by the Harbin Institute of Technology (HIT). The two robotic arms can be used either separately or jointly for assembling laboratory modules, installing and repairing external equipments and instruments, moving cargo and EVA astronaut around the station, and monitoring the station’s external conditions.
The space station is equipped with two robotic arms. The primary arm on the core module is developed by CAST and has a load capacity of 25 tonnes. The secondary arm on the Wentian laboratory module is developed by the Harbin Institute of Technology (HIT). The two robotic arms can be used either separately or jointly for assembling laboratory modules, installing and repairing external equipments and instruments, moving cargo and EVA astronaut around the station, and monitoring the station’s external conditions.
Map showing the orbits of the Tiandong-1, with
Toronto, Canada as the "home" location for tracking. Made at 10:08
EST on 06-01-2013 PreviSat is released under the GNU GPL license version 3. The
map is the generic public domain map from NASA
About The Author:
David Xia of SinoDefence.com and can be reached through email - sinodefenceblog@gmail.com | Thomson Reuters Researcher ID : L-1240-2015 / All Images are sourced from www.sinodefence.com and other open-source platforms.
AIDN: 001-10-2015-0362
