Long March 3B/E launching Beidou-3G2Q

Tiantong-1-03 | Long March 3B/E

Launch Window/Lift Off Time
(Subject to change)
January 19, 2021 – 16:18:00 UTC | 00:18:00 BJT
Mission Name
Tiantong-1-03, the third Tiantong-1 mobile communication satellite
Launch Provider
(What rocket company is launching it?)
China Aerospace and Science Technology Corporation (CASC)
(Who’s paying for this?)
China Telecom
Long March 3B/E
Launch Location
Xichang Space Center (Songlin), Sichuan, China
Payload mass
~5,400 kg (~11900 lbs)
Where is the satellite going?
Geosynchronous Earth Orbit (GSO), ~36,000 km (~22,000 mi)
Will they be attempting to recover the first stage?
No. The boosters of the rocket are not recoverable.
Where will the first stage land?
It will crash back over land in North-West China
Will they be attempting to recover the fairings?
No. The fairings are not recoverable.
Are these fairings new?
How’s the weather looking?
No information available
This will be the:
– 73rd flight of a Long March 3B (any variant)
– 1st Chinese launch in 2021
– 1st launch of a Long March 3B/E variant in 2021

– 3rd orbital launch attempt of 2021
Where to watch
Official livestream (if available)

What’s all this mean?

The China Aerospace and Science Technology Corporation (CASC) will launch the Tiantong-1-03 satellite atop a Long March 3B/E. It is a mobile telecommunication satellite that will be deployed into a Geosynchronous Earth Orbit (GSO).

Tiantong Satellites

China Telecom are the operators of the Tiantong satellites, a set of mobile telecommunication satellites. The satellites are built by China Academy of Space Technology (CAST). The Tiantong 1 set of satellites is part of China’s space-based information infrastructure and is the country’s answer to the Inmarsat network.

Tiantong-1-01, the first satellite of its kind, launched back in 2016 and went to a Geosynchronous Orbit (GSO). Most people are familiar with Geostationary Earth Orbit (GEO). GEO is a special class of GSO. A geosynchronous orbit is one in which it takes 24 hours to orbit the Earth, but this can be at any inclination. The GEO orbit is a GSO orbit with exactly 0° inclination, i.e. an equatorial orbit.

Tiantong 1-02 is the second satellite in the Tiantong 1 system, and it went into orbit on November 12, 2020. It is also in a GSO. CAST derived the Tiantong 1-02 satellite from the DFH-4 platform, unlike its predecessor. According to China Great Wall Industry Corporation (CGWIC), “DFH-4 is the third generation communications satellite bus in China with high power, strong payload capacity, and extended service life. It consists of propulsion module, service modules and solar arrays.” DFH-4 has 10.5 kW solar array power, compared with only 1.7 kW on its predecessor, DFH-3.

Tiantong satellite
Tiantong satellite (Credit: @ChinaScience on Twitter)

Coming only two months later, Tiantong 1-03 is thought to also be built from the DFH-4 satellite platform. It is believed to provide an S-band mobile communications payload.

What are the Tiantong satellites for?

The satellites are tasked with providing all-weather, all-time, stable and reliable mobile communication services to users in China and its surrounding areas, the Middle East and Africa, as well as most sea areas in the Pacific and Indian oceans.

On January 10, 2020, China Telecom officially opened up the Tiantong satellite communication services to all sectors of society, and satellite mobile phones were one of these services.

The satellites, chips, and terminals in the Tiantong system are all developed and produced in China, which has eliminated long-term dependence by Chinese users on foreign satellite mobile communication services. This means that, from the perspective of China, they can rely on their own hardware going forwards.

What is the Long March 3B?

Despite the Chinese rockets having different heritages, most of China’s orbital launch vehicles use the “Long March” (Chang Zheng) naming scheme. The Long March 3B is a three stage rocket, with an optional fourth stage. The rocket has four liquid-fueled side boosters, and first launched in 1996.

The Long March 3B/E, the enhanced version of the Long March 3B, was first launched in 2007 and has greater Geostationary Transfer Orbit (GTO) payload capacity. The enhanced 3B/E’s have a larger first stage and larger side boosters, compared to the original Long March 3B. As a result, its payload capacity to GTO was increased from 5,100 kg to 5,500 kg.

The Long March 3B series features the following sections or stages:

  • Side boosters
  • First (center) stage (ignited at launch)
  • Second stage
  • Third stage
  • Optional fourth stage

Side boosters

There are 4 side boosters that each use one YF-25 engine, which is powered by Unsymmetrical Di-Methyl Hydrazine (UDMH) and Nitrogen Tetroxide (N2O4).

The regular Long March 3B’s side boosters are 15.33 m (50.3 ft) long, but on the enhanced version they are 16.1 m (52.3 ft) long, producing 740 kN of thrust. The YF-25 engine has a specific impulse (ISP) of 260 seconds, and burns for 140 seconds on the 3B/E variant.

First (center) stage

The first stage has 4 YF-21C engines, which also use UDMH / N2O4 for propellant. The first stage has an ISP of 260 seconds and produces 2,960 kN of thrust. The LM-3B first stage is 23.27 m (76.35 ft) tall, but the 3B/E is 24.76 m (81.23 ft) tall.

Long March 3B/E launch with APStar-9
Long March 3B/E launch with APStar-9 (Credit: ChinaNews.com)

Second Stage

The second stage is powered by a single YF-22E engine. However, attitude control is provided by a single YF-23 Vernier engine, and combined, these engines are known as a YF-24 module. The engine runs on UDMH and N2O4 and produces 742 kN of thrust. The second stage is 12.9 m (42.3 ft) tall and burns for 185 seconds.

The Long March 3 family of rockets
The Long March 3 family of rockets (Credit: CGWIC)

Third stage

The third stage is 12.4 m (40.7 ft) long and is powered by 2 YF-75 engines. Unlike the other stages, this stage is powered by liquid hydrogen (LH2) and liquid oxygen (LOX).

The third stage will burn after the second stage is jettisoned, in order to continue to raise the orbital apogee (maximum altitude). Once the target apogee has been achieved, it shuts down. The vehicle will then coast to apogee, where the stage relights and burns to raise the perigee (lowest altitude) of the orbit.

Optional fourth stage

The fourth stage runs on UDMH / N2O4, and has a singular YF-50D engine.


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