On September 29, 2011 China successfully launched its first space station TianGong-1, written in Chinese as 天宫一号, which means heavenly palace 1. With this article I want to give a overview of the TianGong project and an outlook on what we can expect in the next months.
The completely assembled TianGong-1 space station
Two weeks ago China launched the TianGong-1 space station. However, TianGong-1 is a rather tiny station and only works together with the Shenzhou spacecraft. TianGong-1 can be seen as the science part. The ShenZhou space crafts which arrive later are not only a taxi and resources transporter, they will also bring along the habitation module.
TianGong-1 weighs 8,506 kg and has a pressurized volume of 15 m². I think these two numbers are the most important when estimating the size of a space station. Another important number is the electric output of the solar panels, unfortunately the number hasn’t been published. Compared to other stations, the Chinese is really small. The pressurized volume is the inside volume of the completely empty station. Therefore pressurized volume minus volume of stored objects, experiments and cargo equals space for the astronauts. Here are a few space stations for comparison:
|Space Station||Launch date||mass||Pressurized volume||Days occupied|
|Salyut 1 (USSR)||1971-04-19||18,425 Kg||90 m³||24|
|Skylab (USA)||1973-05-14||77,088 kg||283 m³||171|
|MIR (USSR)||1986-02-19||124,340 kg||350 m³||4594|
|ISS (int.)||1998-11-20||417,289 kg||907 m³||4000|
|TianGong-1||2011-09-29||8,506 kg||15 m³||0|
TianGong-1 orbits the earth at an inclination of 42.75 degree, which means at its most northern / southern point of each orbit it is above 42.75 degree latitude. Its altitude currently is at 375 km, which is roughly equal to the ISS. Keep in mind, altitude is constantly changing as there is a very tiny amount of atmosphere that slows down orbiting objects. A very rough estimate is, it loses 1 km of altitude per month, but that depends on a lot of factors like sun activity, aerodynamic properties and current altitude of the station and others. Of course there is some fuel aboard to raise the orbit if necessary.
Time line up to launch
There were rumors about a Chinese space station for a long time. In 1986 a space station plan was presented by the Chinese space agency to leading politicians of that time, but the plans were rejected. Instead a comparatively simple space capsule was chosen, which ultimately led to the ShenZhou space capsule.
In 1999 the space station was authorized, which means engineers started making plans on how the station can be built. At the World Expo 2000 in Hanover a first mockup was show, however it was quite different from today’s TianGong-1. That presentation can be counted as a political message to show the world, China is in the space flight business.
The next few years were pretty quiet, regarding the Chinese space station. The first sketches for a space station involved 2 or 3 ShenZhou space crafts making a rendezvous in space to create a space station. In 2007 a true space station module was announced, TianGong-1. The ShenZhou spacecrafts will merely bring supply and crew up to the space station and act as a habitation module. In 2009 at Chinese new year a scale model of TianGong-1 was finally shown to the public:
During 2011 the media coverage changed, maybe because China wanted to show something to the people. More pictures and videos of TianGong-1 appeared and during the last few months before the start pictures from the construction site were made public every week.
TianGong-1 in the construction site mid-2011
And finally they put the space station on top of a Long March 2F/G rocket at the JiuQuan space center. The original launch day was scheduled in late August, however at 17th of August 2011 a unmanned rocket of the type Long March 2C failed during the launch. These two rockets are to some degree related to each other and the engineers wanted to find out what went wrong before launching TianGong-1. Therefore the launch of the space station was postponed to end September or later. Finally the rocket scientists concluded that the faulty part of the unmanned Long March 2C was not used in the Long March 2F/G and TianGong-1 got green light for late September, just before 1. October which is an important day to praise the country.
The launch was as smooth as it possibly could be. I’ll just ad a picture:
You can also view the video of the launch: TianGong-1 launch video
Currently TianGong-1 is pretty lonely up there. But that will change soon. For late 2011 it is planned to send ShenZhou 8 in an unmanned configuration to the Chinese space station. There it will test the automated rendezvous and docking system. If this test goes well, ShenZhou 8 will return to earth after a few weeks in space.
In 2012 we can expect two manned flights with the ShenZhou spacecraft. ShenZhou 9 and ShenZhou 10. At this moment it is unclear how many Taikonauts will be aboard. Previously some officials said 3 Taikonauts will be sent to the space station with each flight, however lately others voiced their idea of sending only two each flight to be able to stay in space much longer, because each ShenZhou can only transport limited amounts of supply.
To the left you can see a ShenZhou spacecraft as it was used in previous manned Chinese space missions. For TianGong missions the orbital module will be used as habitation module for visitors to the TianGong-1 space station.
China’s plan for the next decade indicates they are serious about building space stations. The rough outline is to launch TianGong-2 in 2013, which will be pretty similar to TianGong-1. For 2015 or 2016 TianGong-3 is planned, which will be bigger. And for the early 2020s an even bigger space station is planned.
China clearly wants to gain knowledge on how to build space stations. Furthermore, a space station creates more economic value than a flight to the moon. Visiting the moon will improve knowledge about the moon. A space station around earth however is best to gain medical knowledge and make biological and material science experiments. And that can be useful for the Chinese industry.