Thursday, March 29, 2018

China Launches Another Pair of BeiDou-3 Navigation Satellites into Space

Long March 3B launch on March 29. Credit: weibo.com

China has successfully launched on Thursday, March 29, a Long March 3B rocket carrying two BeiDou-3 spacecraft for its satellite navigation system. The booster took to the skies lifted at 17:56 GMT (1:56 p.m. EDT) from the LC2 Launch Complex at Xichang Satellite Launch Center (XSLC) in China’s Sichuan province.

Powered by its first stage and four liquid rocket boosters, Long March 3B completed a short vertical ascent after liftoff. Next, the launch vehicle started heading southeast in order to fly over the island of Hainan, toward South China Sea.

Although China keeps the details about the mission under tight wraps, it is assumed that the whole flight should last several hours as the rocket is tasked with inserting the payload into a medium-Earth orbit (MEO). For today’s mission the Long March 3B rocket fles with a Yuanzheng-1 (YZ-1) upper stage attached, which ignited its YF-50D engine some 20 minutes after launch and should burn out about four hours into the flight, releasing the two BeIDou-3 satellites into MEO.

Thursday’s mission was initially targeted for March 12, but was postponed by two and a half weeks. However, Beijing has not informed the public why the flight was rescheduled.

The two passengers of the mission, BeiDou-3 M5 and M6, are based on a newly-developed dedicated satellite bus and weigh about one metric ton a piece. Both satellites have two deployable solar arrays and were designed to be operational for about 12 years. Once deployed, the duo will offer their services from MEO at an altitude of some 13,360 miles (21,500 kilometers), with an inclination of approximately 55.5 degrees.

The BeiDou (BDS) project, named after the Chinese term for the plough or the Big Dipper constellation, was formally launched in 1994. The first BeiDou satellite was sent aloft in 2000. By 2012, a regional network had already begun to take shape, which provided positioning, navigation, timing, and short message services in China and several other Asian countries.

BeiDou-3 M5 and M6 satellites represent the third phase of the BDS system (BeiDou-3). It is the final stage of the establishment of a Chinese space-based navigation architecture. The constellation should consist of 27 BeiDou-3M satellites in MEO, five BeiDou-3G satellites in a geostationary orbit (GTO), and three BeiDou-3I satellites in an inclined geosynchronous satellite orbit (IGSO). The first BeiDou-3 satellite was launched in March of 2015.

BeiDou is expected to provide navigation and positioning services to countries under the “Belt and Road Initiative” (more than 60 countries in Asia, Europe, Oceania and East Africa) by late 2018.

"The BeiDou system not only belongs to China, but the whole world," Yang Changfeng, chief designer of the BeiDou system.

The three-stage Long March 3B rocket that was employed for Thursday’s flight is a 180-foot (55-meter) tall launch vehicle that is capable of sending up to 12 metric tons of payload to low-Earth orbit or 5 metric tons of cargo into GTO. For some launches, this rocket can be equipped with a Yuanzheng-1 upper stage.

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