Long March 5
Long March 5 (LM-5; ), or Changzheng 5 (CZ-5), and also by its nickname "Pang-Wu" (胖五, ""Fat-Five""), 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). As of 2021, a 3-core human -rated variant, tentatively referred to as CZ-5 (DengYue), is under development; this variant will be capable of launching a crewed spacecraft into lunar orbit. The Long March 5 roughly matches the capabilities of American NSSL heavy-lift launch vehicles such as the Delta IV Heavy. It is currently the most powerful member of the Long March rocket family and the world's third most powerful orbital launch vehicle currently in operation, trailing the Falcon Heavy and Delta IV Heavy. 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 vehicle's "return to flight" mission (third launch) successfully occurred on 27 December 2019 with the launch and placement of the experimental Shijian-20 communications satellite into geostationary transfer orbit, thereby opening the way for the successful launch of Tianwen 1 Mars mission, lunar Chang'e 5 sample-return mission, and the modular space station, which require the lifting capabilities of a heavy lift launch vehicle . Development. Since 2010, Long March launches (all versions) have made up 15–25% of the global launch totals. Growing domestic demand for launch services has also allowed China's state launch provider to maintain a healthy manifest. Additionally, China had been able to secure some international launch contracts by offering package deals that bundle launch vehicles with Chinese satellites, thereby circumventing the effects of U.S. embargo. 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, while launch was expected to occur at the new Wenchang Space Launch Site in the southernmost island province of Hainan. In July 2012, a new thrust LOX/kerosene engine to be used on the Long March 5 boosters was test-fired by China. 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. Design and specifications. The chief designer of CZ-5  is Li Dong () of the China Academy of Launch Vehicle Technology (CALT). The CZ-5 family include three primary modular core stages of 5.2-m diameter (maximum). The total length of the vehicle is 60.5 metres and its weight at launch is 643 tons, with a thrust of 833.8 tons. Boosters of various capabilities and diameters ranging from 2.25 metres to 3.35 metres would be assembled from three modular core stages and strap-on stages. The first stage and boosters would have a choice of engines that use different liquid rocket propellants: 1200 kN thrust LOX / kerosene engines or 1550 kN  thrust LOX / LH2. The upper stage would use improved versions of the YF-75 engine. Engine development began in 2000–2001, with testing directed by the China National Space Administration (CNSA) commencing in 2005. Versions of both new engines, the YF-100 and the YF-77, had been successfully tested by mid-2007. The CZ-5 series can deliver ~23 tonnes payload to LEO or ~14 tonnes payload to GTO (geosynchronous transfer orbit). It will replace the CZ-2, CZ-3, and CZ-4 series in service, as well as provide new capabilities not possessed by the previous Long March rocket family. The CZ-5 launch vehicle would consist of  a 5.0-m diameter core stage and four 3.35-m diameter strap-on boosters, which would be able to send a ~22 tonne payload to low Earth orbit (LEO). Six CZ-5 variants were originally planned, but the light variants were cancelled in favor of CZ-6 and CZ-7 family launch vehicles. In 2021, it is revealed that a 3-core variant tentatively named CZ-5(DengYue) is under development for potential crewed lunar missions. Notable launches. First flight. 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. Second flight. Its 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). Third flight. The Y3 mission of the Long March 5 program was launched on 27 December 2019, at about 12:45 UTC from the Wenchang Space Launch Site in Hainan, China. CASC declared the mission a success within an hour of launch, after the Shijian-20 communications satellite was placed in geostationary transfer orbit, thus marking the Long March 5 program's return to flight. Fourth flight (CZ-5B). The fourth flight of the Long March 5 program also marked the debut of the CZ-5B variant. The CZ-5B variant is basically equivalent to the Long March 5 core stage with  its four strapped-on liquid-fueled boosters; in place of the usual second stage of the base configuration, it is anticipated that heavier low Earth orbit payloads, such as components of the future modular space station, would be carried by the 5B variant. 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.