Long March 5

Chinese heavy lift rocket

Long March 5B: 5 May 2020 is a Chinese heavy lift launch vehicle developed by the China Academy of Launch Vehicle Technology (CALT). It is the first Chinese launch vehicle designed to use exclusively non hypergolic liquid propellants. It is the fifth iteration of the Long March rocket family. There are currently two CZ 5 variants: CZ 5 and CZ 5B. The maximum payload capacities are approximately to low Earth orbit (for CZ 5B) and approximately to geostationary transfer orbit (for CZ 5). The first CZ 5 launched from Wenchang Space Launch Site on 3 November 2016 and placed its payload in a suboptimal but workable initial orbit. The second CZ 5 rocket, launched on 2 July 2017, failed due to an engine problem in the first stage. After an interval of almost two and a half years, the Long March 5 successfully returned to flight with its third launch on 27 December 2019, which placed the experimental Shijian 20 communications satellite into geostationary transfer orbit, thereby paving the way for the ultimately successful launch of the Tianwen 1 Mars mission, the lunar Chang'e 5 sample return mission, and the modular space station,

China's main objective for initiating the new CZ 5 program in 2007 was in anticipation of its future requirement for larger LEO and GTO payload capacities during the next 20–30 years period. Formal approval of the Long March 5 program occurred in 2007 following two decades of feasibility studies when funding was finally granted by the Chinese government. At the time, the new rocket was expected to be manufactured at a facility in Tianjin, a coastal city near Beijing,

The first photos of a CZ 5, undergoing tests, were released in March 2015. The first production CZ 5 was shipped from the port of Tianjin in North China to Wenchang Space Launch Site on Hainan Island on 20 September 2015 for launch rehearsals. The maiden flight of the CZ 5 was initially scheduled for 2014, but this subsequently slipped to 2016. The final production and testing of the first CZ 5 rocket to be launched into orbit were completed at its Tianjin manufacturing facility on or about 16 August 2016 and the various segments of the rocket were shipped to the launch center on Hainan island shortly thereafter.

The launch was planned to take place at around 10:00 UTC on 3 November 2016, but several issues, involving an oxygen vent and chilling of the engines, were detected during the preparation, causing a delay of nearly three hours. The final countdown was interrupted three times due to problems with the flight control computer and the tracking software. The rocket finally launched at 12:43 UTC. The second launch on 2 July 2017 experienced an anomaly shortly after launch and was switched to an alternate, gentler trajectory. However, it was declared a failure 45 minutes into the flight. Investigations revealed the source of the second flight's failure to be located in one of the core stage's YF 77 engines (specifically, in the oxidizer's turbo pump).

The fourth flight of the Long March 5 program also marked the debut of the CZ 5B variant. This variant retains the base Long March 5's core stage and its four strap on boosters; however, the CZ 5's second stage (with 2 YF 75D engines) has been removed from the CZ 5B. This variant is used to launch heavy low Earth orbit payloads such as components of the Tiangong space station. The 5B variant may also be considered for launching satellite constellations in the future using the Yuanzheng upper stage. The first flight of the 5B variant ("Y1 mission") carried an uncrewed prototype of China's future deep space crewed spacecraft, and, as a secondary payload, the Flexible Inflatable Cargo Re entry Vehicle. The Y1 mission was launched on 5 May 2020, at 10:00 UTC from the Wenchang Space Launch Site in Hainan Island. CASC declared the launch a success after the payloads were placed in low Earth orbit. The flight's secondary payload, the experimental cargo return craft, malfunctioned during its return to Earth on 6 May 2020. Nevertheless, the return capsule of the prototype next generation crewed spacecraft, the flight's primary payload, successfully landed in north China's Inner Mongolia Autonomous Region at 05:49 UTC, on 8 May 2020. The prototype spacecraft flew in orbit for two days and 19 hours and carried out a series of successful experiments and technological verifications. The Y1 mission's core stage may have been the most massive object to make an uncontrolled re entry since the Soviet Union's Salyut 7 space station in 1991 and the United States' Skylab in 1979, excluding the failed controlled reentry of Space Shuttle Columbia over populated areas of the Continental United States in 2003.

Long March 5B was the workhorse during the Tiangong space station construction. The second Long March 5B mission was the launch of Tianhe core module, the first component of the Chinese space station.

Rockets in the Long March 5 family currently have accumulated a total of 12 launches as of 2024. Of these, 11 were successful with a single failed launch. The cumulative success rate is .