Long March 3B

The Long March 3B/E, also known as 3B/G2, is an enhanced variant of the Long March 3B, featuring an enlarged first stage and boosters, increasing its GTO payload capacity to 5,500 kg (12,100 lb).[11] Its maiden flight took place on 13 May 2007, when it successfully launched Nigeria's NigComSat-1, the first African geosynchronous communications satellite. In 2013, it successfully launched China's first lunar lander Chang'e 3 and lunar rover Yutu.

Since 2015, the Long March 3B and 3C can optionally accommodate a YZ-1 upper stage, which has been used to carry dual launches or BeiDou navigation satellites into medium Earth orbit (MEO).

A modified version of the Long March 3B, the Long March 3C, was developed in the mid-1990s to bridge the gap in payload capacity between the Long March 3B and 3A. It is almost identical to the Long March 3B, but has two boosters instead of four, giving it a reduced GTO payload capacity of 3,800 kg (8,400 lb). Its maiden launch took place on 25 April 2008.

On 14 February 1996, the launch of the first Long March 3B with Intelsat 708 failed just after liftoff when the launch vehicle veered off course and exploded when it hit the ground at T+23 seconds. One person on the ground was killed by the explosion (the total number of casualties is unknown). The cause of the accident was traced to short-circuiting of the vehicle's guidance platform at liftoff.[17]

The participation of Space Systems/Loral in the accident investigation caused great political controversy in the United States since the information provided during the accident investigation would help China improve its rockets and ballistic missiles. The U.S. Congress reclassified satellite technology as a munition and placed it back under the restrictive International Traffic in Arms Regulations in 1998.[18] No license to launch United States spacecraft on Chinese rockets has been approved by the U.S. State Department since then, and an official at the Bureau of Industry and Security emphasized in 2016 that "no U.S.-origin content, regardless of significance, regardless of whether it's incorporated into a foreign-made item, can go to China".[19]

On 31 August 2009, during the launch of Palapa-D, the third stage engine under-performed and placed the satellite into a lower than planned orbit. The satellite was able to make up the performance shortfall using its own engine and reach geosynchronous orbit, but with its lifetime shortened to 10.5 years from the originally projected 15–16 years. The investigation found that the failure was due to burn-through of the engine's gas generator, and that "the most likely cause of the burn-through was a foreign matter or humidity-caused icing in the engine's liquid-hydrogen injectors".[20]

On 19 June 2017, a Long March 3B/E mission carrying ChinaSat-9A ended in partial failure. Officials did not release details regarding the status of the mission for at least 4 hours after liftoff.[21] Two weeks later, on 7 July 2017, officials confirmed that the mission had been anomalous, with Space Daily reporting that "an anomaly was found on the carrier rocket's rolling control thruster, part of the attitude control engine, during the third gliding phase". The failure in the rocket's third stage left the payload in a lower than intended orbit, and the payload was forced to spend two weeks reaching its intended orbit under its own power.[22]

On 9 April 2020, a Long March 3B launcher failed after lifting off from the Xichang Satellite Launch Center in the southwestern Sichuan province at 11:46 UTC during the launch of an Indonesian communications satellite, Palapa-N1 (Nusantara Dua) of a mass of 5500 kg and was expected to enter service in geostationary orbit at 113.0° East, replacing the Palapa-D satellite. But one of the two YF-75 third stage engines appeared failed to ignite, preventing the Palapa-N1 (Nusantara Dua) satellite to reach orbit.[23] Wreckage from the third stage and the Palapa-N1 spacecraft re-entered the atmosphere, leading to sightings of fiery debris in the skies over Guam. With the Long March 3B failure, Chinese rockets have faltered on two missions in less than a month. A Long March 7A rocket failed to place a satellite in orbit on 16 March 2020 after taking off from the Wenchang Spacecraft Launch Site on Hainan Island, located in southern China.[24] After two Chinese launch failures in less than a month, further Chinese launches will be likely delayed until it is sure that the quality control is satisfactory.[25]