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Long March 3B sends a doublet of BeiDou-3 navigation satellites to orbit

Long March 3B launches with two BeiDou-3 satellites on February 12, 2018.

Long March 3B launches with two BeiDou-3 satellites on February 12, 2018. Photo Credit: Xinhua/Liang Keyan

A Long March 3B rocket lifted off from the Xichang Satellite Launch Center (XSLC) on Monday, Feb. 12 on a mission to replenish China’s homegrown satellite navigation system.

The booster took the skies from XSLC’s Launch Complex 2 at 5:03 GMT (0:03 a.m. EST) with a duo of BeiDou-3 navigation satellites. Although Chinese media have not disclosed any details about the mission, it is assumed that the flight lasted a few hours as the payload was intended to be delivered into a medium-Earth orbit (MEO).

Monday’s mission, which delivered the BeiDou-3 M3 and M4 spacecraft to orbit, was originally scheduled for Jan. 11. However, China decided to send BeiDou-3 M7 and M8 on that day instead of M3 and M4. The next launch date was set for Feb. 11, but then the flight was delayed by an additional 24 hours. reports that this delay was due to the visit of Chinese President Xi Jinping to the launch site.

After liftoff, the Long March 3B rocket completed a short vertical ascent. It then started heading southeast in order to fly over the island of Hainan, towards the South China Sea. The launch vehicle flew with a Yuanzheng-1 (YZ-1) upper stage, which ignited its YF-50D engine some 20 minutes after lifting off from the pad. It expended its fuel about three hours into the flight, this was followed by the deployment of the mission’s passengers into MEO.

The successful orbital insertion of the spacecraft was confirmed by Xinhua. The state-run press agency stated that the satellites “entered orbit more than three hours after the launch.”

Parts of the Long March 3B’s boosters apparently fell down to Earth in Tianlin county located in southern China. Various journalists and social media users posted images of the rocket’s wreckage.

BeiDou-3 M3 and BeiDou-3 M4 are based on a newly-developed dedicated satellite bus and weigh about one metric ton a piece.

“China developed a new generation of platform for navigation satellites that enable a single rocket to send two or more satellites into space in 2010,” said Wang Ping, the chief designer of the BeiDou-3 spacecraft.

Both spacecraft have two deployable solar arrays and were designed to be operational for about 12 years. The duo should offer their services from MEO at an altitude of some 13,360 miles (21,500 kilometers), inclined 55.5 degrees.

BeiDou-3 M3 and M4 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. When complete, 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).

Named after the Chinese term for the plough or the Big Dipper constellation, the BeiDou project was formally launched in 1994. The first BeiDou satellite was launched in 2000. By 2012, a regional network had already begun taken shape, which provided positioning, navigation, timing, and short message services in China and several other Asian countries. The first BeiDou-3 satellite was launched in March of 2015.

The three-stage Long March 3B rocket that was used for Monday’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.

Monday’s mission was the 267th flight for a member of the Long March rocket family and the seventh launch out of about 35-40 that China has planned for this year. It was also the third launch of a BeiDou-3 duo within a time span of slightly more than three months.

Beijing’s next launch is currently scheduled for Feb. 20, when the Taurus-1 CubeSat is slated to be orbited from the Taiyuan Satellite Launch Center in China’s Shanxhi Province. However, officials have not yet disclosed which rocket will be employed for this mission.





Tomasz Nowakowski is the owner of Astro Watch, one of the premier astronomy and science-related blogs on the internet. Nowakowski reached out to SpaceFlight Insider in an effort to have the two space-related websites collaborate. Nowakowski's generous offer was gratefully received with the two organizations now working to better relay important developments as they pertain to space exploration.

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