Tiangong Bandwidth Set to Grow [Long March 3B/E]

Another Tianlian-2 satellite is heading toward geostationary orbit.

The Long March 3B/E vehicle lifting off from the Xichang Satellite Launch Center carrying Tialian-2-05.

Blasting off from Launch Complex 2 at the Xichang Satellite Launch Center on April 27th at 23:54 pm China Standard Time (15:54 pm Universal Coordinated Time), a Long March 3B/E headed toward a geostationary transfer orbit, carrying a single satellite.

The satellite launched atop of today’s Long March 3B/E was Tianlian-2-05 (天链二号05星), from the China Academy of Space Technology. This satellite is based on the DongFangHong-4 spacecraft bus, along with the previous satellites of the same series. Just over one month ago, Tianlian-2-04 was launched following a three-year hiatus for the satellite series. The likely strategic decision to launch additional Tianlian-2 satellites is due to increased scientific activity onboard Tiangong, as well as future expansions, and testing of crewed lunar mission hardware in low Earth orbit. All of those activities require greater bandwidth, through more active Tianlian-2 satellites.

The fleet of Tianlian satellites is used to relay communications and data from crewed spacecraft in low Earth orbit, such as the Tiangong Space Station and transiting Shenzhou vehicles, as well as for other critical spacecraft in medium Earth orbit. These satellites also remove communications dead zones where ground stations and communication ships aren’t present for crewed launches. NASA operates a similar series of satellites with its Tracking and Data Relay Satellite constellation.

The patch for the Long March 3B/E’s April 27th 2025 launch mission.

With the increase in geostationary satellite launches from China, various officially undisclosed objects have been released into orbit. Naturally, in the West, this has led to some concern, but Slingshot Aerospace has pointed out that these are likely apogee kick-motors, used to send each satellite toward its target orbit without expending onboard fuel.

Seven Long March 3B/E’s have flown this year with today’s mission, all successfully. Toward the end of last year, the China Academy of Launch Vehicle Technology boasted that they were aiming to launch the Long March 3B/E over a dozen times this year as part of a period of high-frequency launches. With the current launch rate, around twenty launch missions utilizing the rocket could occur before the end of 2025, becoming by far the vehicle’s busiest year.

Today’s mission was the 108th launch of a Long March 3B vehicle, and the 572nd launch of the Long March launch vehicle series. This was also the 23rd launch from China in 2025.

Launch footage via Cosmic Penguin on Twitter.

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Check out the previous Long March 3B/E launch

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What is the Long March 3B/E?

This section is for those less familiar with China's Long March series of launch vehicles.

The Long March 3B is an older-generation geostationary orbit workhorse of the China Academy of Launch Vehicle Technology. The first two stages and four boosters of the rocket burn Dinitrogen Tetroxide and Unsymmetrical Dimethylhydrazine, with liquid hydrogen and liquid oxygen in the third-stage.

Over the rocket's almost twenty-eight-year launch history, two versions of the vehicle have flown, the 3B and 3B/E. Since 2012 only the 3B/E variant has flown due to its increased payload capacity. The payload capacity of the launch vehicle is currently as follows:

• 11,500 kilograms to low Earth orbit

• 7,100 kilograms to a sun-synchronous orbit

• 5,500 kilograms into a geostationary transfer orbit

• 2,000 kilograms into geostationary orbit

The Long March 3B/E launch vehicle at Launch Complex 2 prior to its mission on April 27th.

The first-stage is powered by four YF-21C engines that burn Dinitrogen Tetroxide and Unsymmetrical Dimethylhydrazine to generate 302 tons of thrust, while the boosters are powered by one YF-25 engine burning the same fuel to generate 72 tons of thrust each. Combined the four boosters and first stage generate a thrust of 590 tons. The second stage is powered by one YF-22E and four YF-23F vernier engines that also burn Dinitrogen Tetroxide and Unsymmetrical Dimethylhydrazine to generate 81 tons of thrust. The third-stage is powered by two YF-75 engines that burn liquid hydrogen and liquid oxygen to generate 17 tons of thrust.

On the launch pad, the Long March 3B/E is 56.3 meters tall and weighs 458,970 kilograms when fully fuelled. The first and second-stage have a diameter of 3.35 meters, while the third-stage has a diameter of 3 meters, along with the four boosters diameter of 2.25 meters, and the fairing has a diameter of 4.2 meters.

So far every Long March 3B launch has occurred from the Xichang Satellite Launch Center, in the south of Sichuan province.

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