Sunday, August 26, 2018

Two New BeiDou-3 Navigation Satellites Launched atop Long March 3B

Long March 3B launches with BeiDou-3 M11 and M12 satellites on August 25, 2018. Photo Credit: Xinhua/Liang Keyan.

China successfully launched on Saturday, August 25, its Long March 3B booster carrying two new BeiDou-3 spacecraft to replenish the homegrown satellite navigation network. The launch occurred at 7:52 a.m. local time (23:52 GMT; 7:52 p.m. EDT on August 24) from the Launch Complex 3 of the Xichang Satellite Launch Center (XSLC) in China’s Sichuan Province.

Mission success was confirmed by the state-run Xinhua press agency some nine hours after liftoff.

“China on Saturday successfully sent twin BeiDou navigation satellites into space on a single carrier rocket,” Xinhua informed.

Very little is known about pre-launch preparations and about the orbital flight. Xinhua only noted that both satellites were deployed into orbit more than three hours after the launch and that they will become operational after a series of in-orbit tests.

The duo was most likely inserted into a medium-Earth orbit (MEO) at an altitude of some 13,360 miles (21,500 kilometers) with an inclination of approximately 55.5 degrees.

The two satellites orbited on Saturday are designated BeiDou-3 M11 and M12, and were developed by the Innovation Academy for Microsatellites of the Chinese Academy of Sciences (CAS). Both spacecraft are based on a newly-developed dedicated satellite bus with phased array antenna for navigation signals and a laser retroreflector.

Each BeiDou-3 MEO satellite weighs about one metric ton, has two deployable solar arrays and is designed to be operational for about 12 years. The dimensions a spacecraft of this type are: 7.38 by 3.28 by 4.0 feet (2.25 by 1.0 by 1.22 meters).

BeiDou-3 M11 and M12, which belong to the third phase of the BeiDou (BDS) satellite navigation system, are 35th and 36th satellites of the program. Named after the Chinese term for the Big Dipper, the project was formally launched in 1994 and the first satellite was orbited in 2000. By 2012, a regional network had begun to take shape, which provided positioning, navigation, timing, and short message services in China and several other Asian countries.

China intends to have the BeiDou-3 constellation consisting of some 27 BeiDou-3M satellites in MEO, five BeiDou-3G satellites in a geostationary orbit, and three BeiDou-3I satellites in an inclined geosynchronous satellite orbit. The first BeiDou-3 satellite was launched in March of 2015.

“A basic system with 18 BeiDou-3 satellites orbiting will be in place by the year end, which will serve countries participating in the China-proposed Belt and Road Initiative,” Xinhua informed last month when BeiDou-3 M5 and M6 were launched into space.

The three-stage Long March 3B rocket is 180 feet (55 meters) tall and capable of sending up to 12 metric tons of payload into low-Earth orbit or five metric tons of cargo into a geostationary transfer orbit. For Saturday’s launch, this rocket was equipped with a Yuanzheng-1 (YZ-1) upper stage.

Saturday’s mission was the 283rd flight of the Long March rocket series and the 23rd launch carried out by China in 2018. Beijing’s next orbital flight is currently targeted for September 20 when a Kuaizhou 1A rocket is planned to deliver the Centispace-1 1S into a Sun-synchronous orbit (SSO). However, some other launched may be conducted earlier as China performs many orbital flights without any prior notice.

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