Tianzhou

Tianzhou (paper model)

Tianzhou ( Chinese 天 舟, Pinyin Tiānzhōu  - "sky ship") is an unmanned and non-reusable supply spaceship built by the Chinese Academy for Space Technology . It will be launched with launch vehicles of the Langer Marsch 7 type .

Surname

For the naming of the spaceship, the agency for manned space flight launched a competition on April 8, 2011, in which all Chinese, whether at home or abroad, could submit proposals from April 25 to May 20, 2011. From the 9640 proposals submitted, a commission chaired by the writer Bi Shumin (毕淑敏, * 1952) made a pre-selection of 30 names, from which 377,778 participants then selected 10 names in an internet vote from May 26th to June 20th. After two years of discussion, the commission finally selected “Tianzhou” or “sky ship” from suggestions such as “god dragon”, “dragon ship” etc. because this name expressed its function as a “ cargo ship ” on the one hand and also with the manned one on the other "Shenzhou "- or" Godship "spaceship matched. The name was approved by the State Council of the People's Republic of China and officially announced on October 31, 2013.

Layout and function

The space freighter, which was developed on the basis of the Tiangong 1 space station , originally had a payload of 6.5 t (including 2 t propellant ), the version used from 2021 to supply the Chinese space station with 6.8 t. Its length is 10.6 meters, its maximum diameter 3.35 meters, in both versions it has a take-off weight of 13.5 t when fully loaded. That means up to 48%, in the revised version 50% of the total mass is freight. Inside the freighter there is 18 m³ of empty space for stowing food packages, etc. The propellants transported by Tianzhou are divided into eight tanks with a capacity of 400 liters each, four for the fuel and four for the oxidizer . The freighter's solar modules provide 2.7 kW of energy. Since Tianzhou 2, around 1 kW of this can be branched off to supply the Tianhe core module of the space station with power; on the other hand, the core module can also provide the freighter with up to 2 kW via its own 9 kW solar cell wing, if the latter is powered by the Mass of the space station is shadowed. These amounts of electricity are necessary, among other things, because the internet connection to earth runs through the cargo spacecraft. The astronauts can use mobile devices to communicate with their relatives in video conferences, listen to music or surf the web. Special security measures have been taken so that no malicious programs can be uploaded via this connection to the public Internet (there is also the intranet of the People's Liberation Army) .

With a coupling adapter developed by the Research Institute 805 of the Shanghai Academy of Space Technology , Tianzhou can perform fully automatic rendezvous and coupling maneuvers. As with the Russian Progress transporters , space station crews can take control of the approaching spacecraft. For use with the Chinese space station, which has significantly more mass than the room laboratories of the Tiangong series, a greatly improved, adjustable shock absorption has been used on the coupling adapter since Tianzhou 2. Once docked, the freighter is also used to change the station's orbit with its relatively powerful engines, for example to avoid space debris. Tianzhou 1 was only able to cope with this up to a weight of 8.6 t, since Tianzhou 2 rail maneuvers controlled by the freighter up to a weight of 180 t have been possible, i.e. the final expansion of the station to a 干 shape.

In addition to freight transport, Tianzhou is also used to remove garbage from the space station and to carry out its own autonomous missions. The spaceship can work independently for a total of three months, plus the time it spends docked at the space station. Due to the attitude of the Chinese space station, the engine room of the freighter (the rear, slim section) is often exposed to solar radiation, which can lead to an unacceptable increase in the temperature in the vicinity of the engines. For this reason, the engineers installed 2 shading areas there from Tianzhou, of course at a safety distance from the engines that had previously been determined in numerous simulations. This allowed the temperature around the nozzles to be reduced significantly.

Tianzhou 1 (TZ-1)

The first Tianzhou 1 (TZ-1) was launched on April 20, 2017 at 11:40:45 UTC from launch pad 102 of the Chinese Wenchang Cosmodrome with a CZ-7 launcher to the Tiangong 2 space station . With a launch mass of almost 13 t, Tianzhou-1 was the heaviest cargo that had ever been launched into space by a Chinese launcher. The main task of the Tianzhou 1 mission was to refuel the Tiangong 2 space station, and material was also transported to the space station. The space freighter docked at the station on April 22, 2017. Refueling tests were carried out on April 27 and June 15.

After 60 days of joint flight, the Beijing Space Control Center radioed the order to disconnect on Monday, June 19, 2017 at 01:37 UTC. The retaining mechanism released and the two spacecraft separated from each other. After a pre-programmed sequence, the space freighter withdrew in several steps until it finally reached a position 5000 m behind the space station, where it stayed for 90 minutes. After the control center verified that neither spacecraft had been damaged during the maneuver, the order was given to Tianzhou 1 to orbit the space station. The space transporter flew to a position 5000 m in front of the space station and during this time turned 180 ° around the yaw axis , so that it was now flying backwards. Tiangong 2 also rotated 180 ° around the yaw axis and was now flying forward. The freighter then began braking maneuvers in order to gradually allow the space station to come closer to 30 m, which, however, caused its orbital height to drop for mechanical and physical reasons. H. the freighter had to steer towards the zenith at the same time . Finally, the actual coupling maneuver was initiated, which was completed at 06:55 UTC, a good five hours after the start of the test. The maneuvers carried out during this test and the technology tested for docking from different directions formed an important preliminary stage for the construction of the modular space station at the beginning of the 2020s.

On August 2, Tianzhou 1 launched a small satellite. Another coupling and refueling maneuver took place on September 12, 2017, during which a fast approach was tested, as will later also be carried out on the modular space station. With the maneuver practiced here, astronauts can be at the space station a few hours after take-off instead of the two-day journey to Tiangong 1 and Tiangong 2. After decoupling from the space laboratory, Tianzhou 1 was targeted over the Pacific Ocean on September 22, 2017 Crashed.

Tianzhou 2 (TZ-2)

Tianzhou 2 was originally scheduled to launch on May 19, 2021 and refuel the Tianhe core module of the Chinese space station, which was launched on April 29 of that year . Due to technical problems, however, the start-up process was canceled and a new date was set for May 29th. While Tianzhou 1 needed almost two days for the flight to the Tiangong 2 space laboratory, a new trajectory was tested here that made it possible to reach the space station after just eight hours. Further tests are to be carried out for this purpose. It is hoped that when the technology is fully developed, space travelers will also be able to arrive at the space station within a few hours of take-off.

Besides functioning as a tanker, the freighter brought two Feitian space suits for spacewalks with as well as food and consumer goods for a three-month stay of three flying in June to station astronauts. On this mission, Tianzhou 2 transported 1.95 t of liquid fuel for the station's chemical engines as well as 4.69 t of other material, making a total of 6.64 t. In the hold there were 160 packages with a total of 200 items, including 20 gas bottles and more than ten water bags. The latter not only serves to replenish the water required by the space travelers - drinking water is recovered from wastewater and the moisture in the air we breathe - but above all to produce oxygen by means of electrolysis.

After a few months, the freighter is supposed to decouple again in order to free the stern lock of the core module for Tianzhou 3. However, Tianzhou 2 remains in orbit near the space station. After the crew of Shenzhou 13 will have docked at the lower bow lock in October 2021 , Tianzhou 2 will dock at the forward bow lock. The fuel lines from Tianzhou 3, the core module and Tianzhou 2 are to be connected to a network and refueling attempts are to be carried out via the bow lock. After the actual space station has been completed, the planned Xuntian space telescope will occasionally dock there in order to be refueled and, if necessary, serviced.

Then Tianzhou 2 will be used to test the assembly of the science modules. The empty freighter is to be brought from the forward lock to the port lock using the station's mechanical arm . About 12 months after launch, Tianzhou 2 is said to be deliberately crashed.

Mission overview

No.	Spaceship	Start (UTC)	carrier rocket	Launch site	coupling			crash	Hints
					station	Docking (UTC)	Uncoupling (UTC)
1	Tianzhou 1	April 20, 2017 11:41 am	CZ-7	Wenchang LC-102	Tiangong 2	April 22, 2017, 4:16 am June 19, 2017, 6:55 am	June 19, 2017, 1:37 am September 22, 2017, 8:15 am	Sept. 22, 2017, ~ 10 a.m.	First flight
2	Tianzhou 2	May 29, 2021 12:55 PM	CZ-7	Wenchang LC-102	Chinese space station	May 29, 2021, 9:01 pm

Comparison with other space transporters

Spaceship	progress	Space Shuttle with MPLM	ATV	HTV HTV-X	Dragon 1 Dragon 2	Cygnus	Tianzhou	Dream Chaser
Starting capacity	2.2-2.4 t	9 t	7.7 t	6.0 t 5.8 t	6.0 t	2.0 t (2013) 3.5 t (2015) 3.75 t (2019)	6.5 t (2017) 6.8 t (2021)	5.5 t
Landing capacity	150 kg (with VBK-Raduga )	9 t	-	20 kg (from HTV-7)	3.0 t	-	-	1.75 t
Special skills	Reboost, fuel transfer	Transport of ISPR, transport of external loads, station construction, reboost	Reboost, fuel transfer	Transportation of ISPR , transportation of external loads	Transportation of ISPR, transportation of external loads	Transport of ISPR	Fuel transfer
carrier	Soyuz	STS	Ariane 5	H-2B H3	Falcon 9	Antares / Atlas 5	Long March 7	Vulcan
Start-up costs (rough information)	$ 65 million	$ 450 million	$ 600 million	HTV: $ 300-320 million	$ 150/230 million (Dragon 1/2)	$ 260/220 million (Cygnus 2/3)
Manufacturer	RKK Energija	Alenia Spazio (MPLM)	Airbus Defense and Space	Mitsubishi Electric	SpaceX	Orbital Sciences	CAST	Sierra Nevada
Period of use	since 1978	2001-2011	2008-2015	2009–2020 from 2022	2012–2020 since 2020	since 2014	since 2017	from 2022

italic = planned

Individual evidence

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