Long March 5 version
Long March 5 CZ-5B
The CZ-5B is the Long March 5 variant built for heavy low Earth orbit payloads. It keeps the core stage and the four boosters of the CZ-5 but drops the cryogenic second stage: the core itself reaches orbit with the payload on top, which lets it place about 25,000 kg at 200 km altitude, the largest capacity of any Chinese launcher. It stands 53.66 m against the 56.97 m of the standard version and lifts off at 837,500 kg. It flew seven times between 5 May 2020 and 13 August 2025.
- May 5, 2020
- First launch
- 25,000 kg
- LEO capacity
- No
- Reusable
History
A rocket for the space station
The fourth mission of the Long March 5 programme introduced the CZ-5B on 5 May 2020. The variant was born from a very specific requirement: to place the modules of the Tiangong station in low Earth orbit, twenty-tonne pieces that no other Chinese rocket could lift. To achieve it the engineers of the China Academy of Launch Vehicle Technology did something unusual — they removed the second stage. The hydrolox core, with its two YF-77 engines and the four kerolox boosters, pushes the payload straight to orbit, so the fairing, far larger than the CZ-5's, sits on the core itself.
The maiden flight carried an uncrewed prototype of the Mengzhou lunar crew module. In 2021 and 2022 the CZ-5B lofted the three station modules: Tianhe, Wentian and Mengtian. Since 2024 it has also been deploying ten-satellite clusters of the Guowang internet constellation into polar orbit.
The reentry controversy
Dropping the second stage has an awkward consequence: the core stage reaches orbit and comes back uncontrolled. The core of the first flight, in May 2020, was probably the most massive object to make an uncontrolled reentry since the Soviet Salyut 7 in 1991 and the American Skylab in 1979; debris was found in a village in Ivory Coast. The core of the second mission stayed in a decaying orbit for over a week and reentered above the Arabian Peninsula in May 2021, with a possible debris footprint in the Indian Ocean near the Maldives. The CZ-5B reentries opened an international debate on responsibility in orbital stage design.
Status
The seventh and so far last CZ-5B flight took place on 13 August 2025. The variant is due to launch the Xuntian space telescope, which will co-orbit with Tiangong, and is being considered with a Yuanzheng upper stage for constellation deployment.