The China Aerospace Science and Technology Corporation (CASC) is the main contractor for the Chinese space program. It is state-owned and has a number of subordinate entities which design, develop and manufacture a range of spacecraft, launch vehicles, strategic and tactical missile systems, and ground equipment. It was officially established in July 1999 as part of a Chinese government reform drive, having previously been one part of the former China Aerospace Corporation. Various incarnations of the program date back to 1956.
The Long March 3B / E (G2) (CZ-3B / E) is one of the most successful medium-range launchers and the strongest variant of the CZ-3 series. It was specially developed for the transport of heavy communications satellites into a geostationary transfer orbit. The additional designation "E" stands for a higher payload fairing, stretched boosters and extended fuel tanks at the first stage, over the CZ-3B.
The YF-20 is a basic engine when mounted in a four engine module forms the YF-21.
The YF-24E is a combination of (1)YF-22E and (4)YF-23F
The YF-75 engine replaced the YF-73 it is used in the H-18 third stage of the Long March rocket 3A,3B,3C.