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China successfully launches a duo of BeiDou-3 navigation satellites

CZ-3B / YZ-1 launch with the BeiDou-3 duo (M1 and M2)

CZ-3B / YZ-1 launch with the BeiDou-3 duo (M1 and M2). Photo Credit: Yang Zhiyuan / Xinhua

Using a Long March 3B booster, China successfully launched its newest duo of BeiDou-3 navigation satellites to orbit. The rocket took to the skies on Sunday, November 5, 2017, at around 11:44 UTC (6:44 a.m. EST) from the LC3 Launch Complex at the Xichang Satellite Launch Center, located in China’s Sichuan province.

The mission was initially planned to launch in July; however, China experienced a partial failure of its Long March 3B rocket and a failure of its Long March 5 booster, which forced Beijing to halt orbital flights for almost three months.

Very little is known about Sunday’s pre-launch and launch preparations as Chinese media have not released any details about the mission. In mid-September, the state-run Xinhua press agency only noted that the launch would take place in November. About a month later, the rocket was rolled out to the launch pad.

Beidou Navigational Satellite System logo image credit BNSS

Beidou Navigational Satellite System logo. Image Credit: BNSS

The Long March 3B rocket started its short vertical flight on Sunday by firing its core stage equipped with a quartet of YF-21C engines and four strap-on boosters fitted with one YF-25 motor each. A few seconds later, the launch vehicle conducted a pitch and roll maneuver and turned Southeasterly to begin flying over the Pacific Ocean.

The boosters were jettisoned some two minutes and 20 seconds into the flight. Afterward, the core stage continued to power the rocket alone for about 18 seconds, until it also detached from the launch vehicle.

At this point in the flight, the second stage took control of the mission firing its DaFY-20-1 main engine. It powered the launch vehicle for nearly three minutes until it was separated some five and a half minutes after liftoff. It was at this point in the flight that the protective payload fairing, its job of shielding the spacecraft through Earth’s turbulent atmosphere now complete, detached and left to fall back to Earth.

What took place during the next part of the mission’s timeline is uncertain. However, the rocket’s third stage most likely powered the mission for the next 10-20 minutes, until its separation. Then, the Yuanzheng-1 (YZ-1) upper stage started its roughly six-hour-long mission to deliver the dual payload into orbit.

The two BeiDou-3 satellites will reside in a medium-Earth orbit at an altitude of 13,360 miles (21,500 kilometers), inclined 55.5 degrees.

The passengers of Sunday’s mission were designated BeiDou-3 M1 and BeiDou-3 M2. 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 a medium-Earth orbit (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. 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 by 2020.

The three-stage Long March 3B rocket used in Sunday’s flight is a 180-foot (55-meter) tall booster capable of launching up to 12 metric tons of payload to low-Earth orbit or 5 metric tons of cargo into a Geostationary Transfer Orbit (GTO). For some launches, this rocket could be optionally equipped with a Yuanzheng-1 upper stage.

Sunday’s mission was the 11th flight for China and the fifth orbital mission conducted from Xichang this year. The next Chinese launch is currently scheduled for November 15, when a Long March 4C rocket is slated to orbit the country’s Fengyun 3D meteorology satellite and the Head-1 ship tracking spacecraft for the Dutch company Head Aerospace.

Video courtesy of CCTV+



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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