Tianlian

Tianlian
Manufacturer	China Academy of Space Technology (CAST)
Country of origin	China
Operator	China Aerospace Science and Technology Corporation (CASC)
Applications	Tracking and Data Relay Satellite System
Specifications
Bus	DFH-3 - first generation; DFH-4 - second generation;
Regime	Geostationary
Production
Status	In service
Launched	8
Operational	8
Maiden launch	Tianlian I-01; 25 April 2008
Last launch	Tianlian II-03; 12 July 2022

Tianlian (Simplified Chinese: 天链, Traditional Chinese: 天鏈, English: Sky Link) also known as CTDRS, is a Chinese data relay communication satellite constellation. The constellation serves to relay data from ground stations to spacecraft and rockets, most significantly China's crewed spaceflight program. The system currently consists of seven satellites in two generations, with the first satellite being launched in 2008.

Mission

Tianlian is used to provide real-time communications between orbiting satellites and ground control stations. The Chinese tracking and data relay satellites were developed by the China Academy of Space Technology (CAST) and it is similar to the American Tracking and Data Relay Satellite System (TDRSS) in concept. The system is designed to support near-real-time communications between orbiting spacecraft and ground control, as well as complement the ground-based space tracking and telemetry stations and ships in tracking spacecraft.^[1] This is necessary because ground stations can only maintain contact with a satellite while it is overhead. Positioning multiple satellites in geostationary orbit ensures that the ground station and satellite are both always in view of at least one relay satellite, allowing for constant communication between the ground station and target satellite. The system provides data relay services for crewed Shenzhou missions, from Shenzhou 7 onwards, the Tiangong space station, and interplanetary missions.^[2]^[3]^[4] All satellites were launched from the Xichang Satellite Launch Center and operate in geostationary orbit.^[5]^[6]^[7]^[8]

Tianlian I

Tianlian I consists of five satellites, all based on the DFH-3 satellite bus. The first satellite of the series, Tianlian I-01, was launched on the maiden flight of the Long March 3C launch vehicle on 25 April 2008.^[9]^[10] With the launch of Tianlian I-03, a spacecraft could be tracked for 70% of its orbit, compared to only 15% without the constellation.^[11]

Tianlian II

Tianlian II is the second generation of the constellation and currently consists of 3 satellites based on the DFH-4 satellite bus. The second generation system greatly improves data transmission rates and its multi-targeting ability. This in turn improves spacecraft operational safety and flexibility.^[12]^[13]

Satellites


Satellite	Simplified Chinese Name	Launch (UTC)^[14]	Carrier Rocket^[14]	Launch Site^[14]	Bus	Longitude^[15]	Status	COSPAR ID	SATCAT no.
First Generation
Tianlian I-01	天链一号01星	25 April 2008, 15:35	Long March 3C	XSLC LC-2	DFH-3	77.0° East	Active	2008-019A	32779
Tianlian I-02	天链一号02星	11 July 2011, 15:41	Long March 3C	XSLC LC-2	DFH-3	176.72° East	Active	2011-032A	37737
Tianlian I-03	天链一号03星	25 July 2012, 15:43	Long March 3C	XSLC LC-2	DFH-3	16.86° East	Active	2012-040A	38730
Tianlian I-04	天链一号04星	22 November 2016, 15:24	Long March 3C	XSLC LC-2	DFH-3	76.95° East	Active	2016-072A	41869
Tianlian I-05	天链一号05星	6 July 2021, 15:53	Long March 3C	XSLC LC-2	DFH-3	106.2653° East	Active	2021-063A	49011
Second Generation
Tianlian II-01	天链二号01星	31 March 2019, 15:51	Long March 3B	XSLC LC-3	DFH-4	79.9° East	Active	2019-017A	44076
Tianlian II-02	天链二号02星	13 December 2021, 16:09	Long March 3B	XSLC LC-3	DFH-4	171.04° East	Active	2021-124A	50005
Tianlian II-03	天链二号03星	12 July 2022, 16:30	Long March 3B	XSLC LC-2	DFH-4		Active	2022-078A	53100

References

^ "Display: Tianlian 2-01 2019-017A". nssdc.gsfc.nasa.gov. NASA. Retrieved 16 November 2020. This article incorporates text from this source, which is in the public domain.
^ "China's relay satellites facilitate clear, smooth space-ground communication". Xinhua News Agency. 24 June 2021. Retrieved 29 June 2021.
^ Stephen Clark (25 April 2008). "Chinese data relay spacecraft put into orbit". Spaceflight Now. Retrieved 26 April 2008.
^ Li, Guoli; Wang, Ran (21 July 2020). "我国天基测控系统团队完成多项技术状态准备静待天问一号发射" (in Chinese). Xinhua News Agency. Retrieved 23 June 2021.
^ David Todd (26 July 2012). "Chinese data relay satellite TianLian-1C is launched successfully on a Long March 3C". Flightglobal. Retrieved 17 August 2012.
^ "Display: Tianlian 1-02 2011-032A". NASA. 14 May 2020. Retrieved 11 December 2020. This article incorporates text from this source, which is in the public domain.
^ "Display: Tianlian 1-03 2012-040A". NASA. 14 May 2020. Retrieved 11 December 2020. This article incorporates text from this source, which is in the public domain.
^ "Display: Tianlian 1-04 2016-072A". NASA. 14 May 2020. Retrieved 11 December 2020. This article incorporates text from this source, which is in the public domain.
^ Yan Liang (25 April 2008). "China blasts off first data relay satellite". Xinhua. Archived from the original on 29 April 2008. Retrieved 26 April 2008.
^ 我国成功发射首颗数据中继卫星(组图)
^ Xin Dingding (27 July 2012). "Satellite launch completes network". China Daily. Retrieved 17 August 2012.
^ "中国成功发射"天链二号01星"-中新网". chinanews.com. Retrieved 16 November 2020.
^ "China successfully launches second generation data relay satellite". The Economic Times. Retrieved 16 November 2020.
^ ^a ^b ^c McDowell, Jonathan. "Launch Log". Jonathan's Space Report. Retrieved 11 December 2020.
^ "Union of Concerned Scientists Satellite Database". UCS. 1 January 2021. Retrieved 8 July 2021.

[Display-1] "Display: Tianlian 2-01 2019-017A". nssdc.gsfc.nasa.gov. NASA. Retrieved 16 November 2020. This article incorporates text from this source, which is in the public domain.

[2] "China's relay satellites facilitate clear, smooth space-ground communication". Xinhua News Agency. 24 June 2021. Retrieved 29 June 2021.

[SFN-3] Stephen Clark (25 April 2008). "Chinese data relay spacecraft put into orbit". Spaceflight Now. Retrieved 26 April 2008.

[4] Li, Guoli; Wang, Ran (21 July 2020). "我国天基测控系统团队完成多项技术状态准备静待天问一号发射" (in Chinese). Xinhua News Agency. Retrieved 23 June 2021.

[5] David Todd (26 July 2012). "Chinese data relay satellite TianLian-1C is launched successfully on a Long March 3C". Flightglobal. Retrieved 17 August 2012.

[Display02-6] "Display: Tianlian 1-02 2011-032A". NASA. 14 May 2020. Retrieved 11 December 2020. This article incorporates text from this source, which is in the public domain.

[Display03-7] "Display: Tianlian 1-03 2012-040A". NASA. 14 May 2020. Retrieved 11 December 2020. This article incorporates text from this source, which is in the public domain.

[Display04-8] "Display: Tianlian 1-04 2016-072A". NASA. 14 May 2020. Retrieved 11 December 2020. This article incorporates text from this source, which is in the public domain.

[Launch-9] Yan Liang (25 April 2008). "China blasts off first data relay satellite". Xinhua. Archived from the original on 29 April 2008. Retrieved 26 April 2008.

[10] 我国成功发射首颗数据中继卫星(组图)

[11] Xin Dingding (27 July 2012). "Satellite launch completes network". China Daily. Retrieved 17 August 2012.

[:0-12] "中国成功发射"天链二号01星"-中新网". chinanews.com. Retrieved 16 November 2020.

[13] "China successfully launches second generation data relay satellite". The Economic Times. Retrieved 16 November 2020.

[launchlog-14] McDowell, Jonathan. "Launch Log". Jonathan's Space Report. Retrieved 11 December 2020.

[ucs-15] "Union of Concerned Scientists Satellite Database". UCS. 1 January 2021. Retrieved 8 July 2021.

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v t e Chinese spacecraft
Earth observation	Double Star (joint with ESA) Fengyun Gaofen FSW Huanjing HY Jilin Shiyan SMMS TanSat Tansuo Tianhui Yaogan Ziyuan
Communication and engineering	Dong Fang Hong FH-1 Apstar APMT Asiasat ChinaSat ChinaStar HKSTG LGSP OlympicSat Qianfan Shijian Sinosat Tiantong 1 Tsinghua-1 Xiwang 1
Data relay satellite system	Queqiao and Queqiao 2 Tiandu 1 and 2 Tianlian Constellation
Satellite navigation system	BeiDou-1 BeiDou-2 Beidou-3
Astronomical observation	ASO-S CHASE DAMPE GECAM HXMT Kuafu Longjiang-2 Queqiao Lobster Eye Imager for Astronomy Einstein Probe (joint with ESA) SST SVOM Xuntian SMILE
Lunar exploration	Chinese Lunar Exploration Program Chang'e 1 Chang'e 2 Chang'e 3 Yutu Chang'e 5-T1 Chang'e 4 Yutu-2 Chang'e 5 Chang'e 6 Chang'e 7 Chang'e 8
Planetary exploration	Yinghuo-1 Chang'e 2 Tianwen-1 Zhurong Shensuo Tianwen-2 Tianwen-3 Tianwen-4
Microsatellites	Fengniao Xinyan
Future spacecraft in italics.

v t e ← 2007 Orbital launches in 2008 2009 →
January	Thuraya 3 TecSAR Ekspress AM-33
February	Progress M-63 STS-122 (Columbus) Thor 5 Kizuna
March	Jules Verne ATV STS-123 (Kibō ELM-PS, Dextre, Spacelab MD002) USA-200 AMC-14 USA-201 DirecTV-11 SAR-Lupe 4
April	Soyuz TMA-12 ICO G1 C/NOFS Vinasat-1, Star One C2 Tianlian I-01 GIOVE-B Cartosat-2A, Rubin-8, AAUSat-2, CanX-2, CanX-6, Compass-1, CUTE-1.7 + APD II, Delfi-C3, SEEDS-2 Amos-3
May	Progress M-64 Galaxy 18 Kosmos 2437, Kosmos 2438, Kosmos 2439, Yubileiny Fengyun 3A STS-124 (Kibō PM)
June	ChinaSat 9 Fermi Skynet 5C, Türksat 3A Orbcomm FM29, Orbcomm FM37, Orbcomm FM38, Orbcomm FM39, Orbcomm FM40, Orbcomm FM41 OSTM/Jason-2 Kosmos 2440
July	Badr-6, ProtoStar 1 EchoStar XI SAR-Lupe 5 Kosmos 2441
August	Trailblazer, NanoSail-D, PRESat, Explorers Superbird-C2, AMC-21 Omid Inmarsat-4 F3 Tachys, Mati, Choma, Choros, Trochia
September	Huan Jing 1A, Huan Jing 1B GeoEye-1 Progress M-65 Nimiq-4 Galaxy 19 Kosmos 2442, Kosmos 2243, Kosmos 2444 Shenzhou 7 (Banxing-1) Ratsat
October	THEOS Soyuz TMA-13 IBEX Chandrayaan-1 (MIP) Shijian 6E, Shijian 6F COSMO-3 Venesat-1
November	Chuang Xin 1B, Shiyan Weixing 3 Astra 1M Kosmos 2445 STS-126 (Leonardo MPLM, PSSC-1) Progress M-01M
December	Yaogan 4 Kosmos 2446 Yaogan 5 Hot Bird 9, Eutelsat W2M Fengyun 2E Kosmos 2447, Kosmos 2448, Kosmos 2449
Launches are separated by dots ( • ), payloads by commas ( , ), multiple names for the same satellite by slashes ( / ). Crewed flights are underlined. Launch failures are marked with the † sign. Payloads deployed from other spacecraft are (enclosed in parentheses).