China launches two BeiDou-3 spacecraft to replenish its homegrown satellite navigation system
Long March 3B lifts off with two BeiDou-3 satellites on January 11, 2018. Photo Credit: Xinhua/Liang Keyan
China has conducted its second flight of 2018 by launching a Long March 3B rocket with a duo of BeiDou-3 spacecraft for its homegrown BieDou Navigation Satellite System (BDS).
The Long March 3B lifted off at 23:18 GMT (6:18 p.m. EST) on Thursday, January 11, from Launch Complex 2 at the Xichang Satellite Launch Center (XSLC) in China’s Sichuan Province.
Artist’s depiction of Beidou-3 navigation satellite. Image Credit: China Academy of Sciences
The Long March 3B booster most likely stuck to its nominal flight plan, starting with a short vertical ascent before it began heading in a southeasterly direction. The rocket’s first stage burned for about two minutes and 20 seconds – accelerating the launch vehicle throughout the first phase of the flight. Some 20 seconds later, the first stage was jettisoned and the second stage assumed control over the flight.
The rocket’s second stage, burned for about three minutes, continuing to lift the spacecraft, raising its altitude. When the second stage separated, the third stage led the payload higher, and was detached at approximately 20 minutes into the flight. Then, the Yuanzheng-1 (YZ-1) upper stage commenced its roughly four-hour-long journey to deliver its precious cargo to a medium-Earth orbit (MEO) at an altitude of some 13,360 miles (21,500 kilometers), with an inclination of 55.5 degrees.
China has kept the details about both the mission and the pre-launch preparations under wraps. However, the information released by Chinese media indicate that the launch was originally scheduled for November 2017, but was later delayed by one month. Then, the officials decided to postpone it once again, this time to January of this year (2018).
The satellites launched by the Long March 3B on Thursday received designation BeiDou-3 M7 and BeiDou-3 M8 (26th and 27th satellites of the BeiDou system). They are based on a newly-developed dedicated satellite bus and weigh about one metric ton each. Both spacecraft have two deployable solar arrays and were designed to be operational for about 12 years.
The two newly-launched 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 will 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).
“Compared to earlier generation satellites, the BeiDou-3 is able to send signals that are better compatible with other satellite navigation systems and provide satellite-based augmentation, as well as search and rescue services in accordance with international standards,” the state-run Xinhua press agency informs.
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 sent aloft 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. China plans to expand the BeiDou services to most of the countries covered in its “Belt and Road” initiative by 2018, and it hopes to offer global coverage as early as 2020.
The three-stage Long March 3B rocket that was employed for Thursday’s flight is a 180-foot (55-meter) tall launch vehicle 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 could be optionally equipped with a Yuanzheng-1 upper stage.
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