Monday, February 12, 2018

Long March 3B Sends a Doublet of BeiDou-3 Navigation Satellites into Orbit

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 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 doublet of BeiDou-3 navigation satellites. Although Chinese media have not disclosed any details about the mission, it is assumed that the flight lasted few hours as the payload was intended to be delivered into a medium-Earth orbit (MEO).

Monday’s mission, which delivered BeiDou-3 M3 and M4 spacecraft into orbit, was originally scheduled for January 11. However, China decided to send BeiDou-3 M7 and M8 on that day instead of M3 and M4. Next launch date was set for February 11, but then the flight was delayed by 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. Next, it started heading southeast in order to fly over the island of Hainan, towards South China Sea. The launch vehicle flew in a configuration with the Yuanzheng-1 (YZ-1) upper stage, which ignited its YF-50D engine some 20 minutes after liftoff and burnt out of fuel about three hours into the flight, what was followed by the deployment of the mission’s passengers into MEO.

The successful orbital insertion was confirmed by Xinhua. The state-run press agency informs 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 are posting pictures 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 BeiDou-3 spacecraft.

Both spacecraft have two deployable solar arrays and were designed to be operational for about 12 years. The duo will 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. 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 not launched until 2000, however. Nonetheless, by 2012, a regional network had already 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 launch of the Long March rocket family and the seventh orbital mission out of about 35-40 for China 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 February 20, when the Taurus-1 CubeSat will be orbited from the Taiyuan Satellite Launch Center in China’s Shanxhi Province. However, the officials have not yet disclosed which rocket will be employed for this mission.

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