China launched the Long March 5, its largest-ever rocket

The 879-ton rocket flew an experimental satellite into space.

China’s space program has surged forward once more, having launched its largest-ever rocket, the Long March 5 (“Chang Zheng 5” in Chinese). Built by the Chinese Academy of Launch Vehicle Technology, the heavy space launch LM-5 has a thrust of 1060 tons and a payload capacity of 25 tons, putting it in the same class as global heavyweights like the American Atlas V, Delta IV Heavy, and European Ariane V. The Long March 5 launched on Nov. 3, ultimately carrying the experimental Shijian 17 electronic propulsion satellite (pictured below) into geostationary orbit (GEO).

Long March Rocket Family

This CASIC graphic goes into detail on the various Long March 5 variants, including the 25 ton payload to low earth orbit, and 14 ton payload to geosynchronous earth orbit (the later is taller since it has an additional stage to reach the higher orbit).

Originally, there would have been six LM-5 variants, but they have been superseded by the Long March 6, which first flew in September 2015, and Long March 7 in June 2016. Together, the Long March 5, 6, and 7 will be the workhorses of the modernized Chinese space launch program.

Rollout

After nine years of research and development, the LM-5 rolled out in October 2016 for its first flight.

The LM-5’s research and development phase began in 2007, followed by fabrication of the rocket fuselage, with integrated testing of components like fuel lines, propellant tanks, jetpumps, and electronic controls, beginning November 2015. With a fuselage skin only 3 millimeters thick, the LM-5’s safety features include doubly redundant critical systems, such as electronic controls. LM-5’s rocket motors burn liquid oxygen and liquid hydrogen (LOX/LH), with only water as a byproduct, making it very environmentally friendly compared to previous Long March rockets, which used dinitrogen tetroxide and the carcinogenic unsymmetrical dimethylhydrazine.

Core Stage

The core of the LM-5’s first stage consists of a 16.4-foot-diameter rocket with two LH/LOX YF-77 engines, each producing 120 tons of thrust, for a total 240 tons of thrust.

The LM-5 has a payload faring diameter of 17 feet, enabling it to carry much wider cargos than smaller previous Chinese rockets. This is critical for payloads like permanent space station modules and large diameter spy satellites. Both LM-5 variants have a 16.4-foot diameter for the first stage and uses four booster rockets. Each booster rocket has a thrust of over 140 tons from its twin YF-77 engines.

Second Act

The LM-5E’s second stage consists of two 10-ton thrust YF-75D engines for orbit maneuvers and power to break free of LEO to reach a GTO position.

The LM-5 that flew on Nov. 3 was the Long March 5E variant, which is geared toward geostationary orbit (GTO) launches. In its first stage, it uses two 72-ton thrust YF-77 liquid hydrogen and oxygen engines in its core stage, assisted by its four boosters. Operating in the vacuum of deep space, the Yuanzheng 2 (YZ-2)”space tug” and second stage, powered by two 10-ton thrust YF-75D engines, places the payload into GEO. Objects in GEO are high enough to stay over the same geographical location, making them critical for activities which require continuous line of sight to specific areas, like communications and navigation.

LM-5 Boosters

The Long March 5’s four boosters each use twin YF-100 engines for a combined thrust of 240 tons from each booster. The role of boosters in space launch is to provide an initial surge of thrust to give momentum and velocity to the longer burning core stage.

In contrast, the Long March 5B deletes the second stage, but retains the same four booster set-up. The weight savings from removing the second stage LM-5B enable it to carry 25 tons to low earth orbit (LEO), including massive payloads like space stations. In contrast, the previous Chinese rocket, the Long March 2, could only carry 10 ton payloads into LEO.

China Martian Probe Mission
China’s Martian rover will come equipped with various scientific tools and instruments, such as a laser spectrometer. In addition to meeting the demands of Martian environmental challenges like atmospheric interference with solar power collection, Chinese scientists hope the rover will make new discoveries about Martian characteristics like weather and geology. Only the LM-5E’s large GTO payload can launch the Chinese Martian rover for its 2018-2019 target date. xyz at China Defense Forum

The LM-5 has a long mission manifest in the years to come. Next year, it’s rumored to be launching a next generation Chinese military communications satellite to GEO, and then the Chang’e 5 lunar soil return mission and the Martian rover in 2018-19. More heavy lifting will follow, for the 20-ton modules of the Chinese permanent space station. Potential future missions after that include launching large spy satellites, and even a possible manned lunar mission involving multiple LM-5s.

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