China launches Algerian communications satellite atop Long March 3B
China successfully launched a Long March 3B rocket on Sunday, December 10, 2017, with the first Algerian geostationary communications satellite, known as Alcomsat-1. Liftoff took place at 16:40 GMT (11:40 a.m. EST) from the Launch Complex 2 at the Xichang Satellite Launch Center (XSLC) in China’s Sichuan Province.
The satellite was initially planned to be launched in 2014, rescheduled to June 2017, and finally postponed by six months due to launch failures of Long March 3B and Long March 5 rockets that occurred in mid-2017. The final launch date was announced in early November. While this flight was performed for a foreign customer, not many details were released by Chinese media about the pre-launch preparations or about the mission itself.
The Long March 3B commenced a short vertical climb after liftoff. After ascending for a few seconds, the launch vehicle performed a pitch and roll maneuver and turned southeasterly to begin flying over the Pacific Ocean.
The shutdown of the four boosters occurred about two minutes and 20 seconds into the flight and were jettisoned about one minute later. Then, the vehicle continued its mission powered by its core stage (or first stage) alone and its one four-chamber engine, until its separation about two minutes and 40 seconds after the launch.
The second stage moved the mission forward, burning its engines for approximately three minutes until the rocket’s third stage took over control of the flight.
The vehicle’s third stage, fitted with one YF-75 engine, completed the deployment of its payload. The Alcomsat-1 satellite was released from the launch vehicle most likely about 26 minutes after liftoff and will be placed into a geostationary orbit (GEO).
The Alcomsat-1 satellite
Built by the China Academy of Space Technology (CAST), Alcomsat-1 is based on the DFH-4 platform. DFH-4 is the third-generation communications satellite bus and is described as having high power, strong payload capacity, and extended service life. It consists of a propulsion module, service modules, and two deployable solar arrays.
Alcomsat-1 weighs 5.2 metric tons and is equipped with both transponders in Ku-band, Ka-band for civil applications, and X-band, as well as UHF and EHF for the needs of the military and strategic state sectors. It will be operated by Algerian Space Agency (ASAL) for 15 years.
Alcomsat-1 is part of Algeria’s National Space Program (NSP). The satellite was launched to increase the capacity of the country’s national telecommunications network, offering mainly communications, and broadcasting services.
The Long March 3B/E rocket
The three-stage, 180-foot (55-meter) tall Long March 3B rocket that was used for Sunday’s flight is capable of launching up to 12 metric tons of payload to low-Earth orbit (LEO) or 5 metric tons of cargo to a geostationary transfer orbit (GTO).
The 3B/E version that was employed for the mission is an enhanced variant of the rocket, featuring an enlarged first stage and boosters, improved computer systems, and a larger payload fairing. The rocket’s first two stages, as well as the four strap-on boosters, use hypergolic fuel (unsymmetrical dimethylhydrazine with nitrogen tetroxide as the oxidizer), whereas the third stage burns cryogenic fuel (liquid hydrogen with liquid oxygen as the oxidizer).
This configuration of the launch vehicle was brought into service in 2007 to increase the rocket’s GTO cargo capacity – to allow it to be capable of lifting heavier GEO communications satellites. The Long March 3B is powered by its core stage equipped with a quartet of YF-21C engines and four strap-on boosters fitted with one YF-25 motor each.
Sunday’s flight was the 258th flight of the Long March rocket series. It was also the seventh orbital launch from XSLC and the 16th orbital mission for China in 2017. Until year end, Beijing plans to conduct another three or four space launches.
Video courtesy of CCTV+
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