Sunday, November 5, 2017

China Successfully Launches a Duo of BeiDou-3 Navigation Satellites

Long March 3B launch on November 5. Credit: news.cn

Using a Long March 3B booster China successfully launched into space its newest duo of BeiDou-3 navigation satellites. The rocket took to the skies Sunday, November 5 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 be launched in July, however China experienced a partial failure of its Long March 3B launcher and and a failure of its Long March 5 booster, what forced Beijing to halt orbital flights for nearly three months.

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

The Long March 3B rocket started its short vertical flight on Sunday, firing its core stage equipped with a quartet of YF-21C engines and four strap-on boosters fitted with one YF-25 motor each. 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 was also detached from the launch vehicle. 

Next, the second stage took control over the mission firing its DaFY-20-1 main engine. It powered the launch vehicle for nearly three minutes, until it was separated approximately five and a half minutes after liftoff. During this phase of the flight, the protective payload fairing was detached.

The exact timeline of the rest of the flight 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 about 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 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 into 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.

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

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