July 21, 2018

Chinese navigation network expanded with pair of new Beidou satellites


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A Long March 3B rocket launched from the Xichang space center at 2318 GMT (6:18 p.m. EST) on Jan. 11. Credit: Xinhua

Two satellites destined to join China’s Beidou network successfully launched Thursday aboard a Long March 3B rocket, the first two of up to 18 new Chinese navigation craft scheduled for deployment this year.

The newest Beidou satellites lifted off at 2318 GMT (6:18 p.m. EST) Thursday from the Xichang launch center in Sichuan province, a mountainous region in the southwest part of China, the state-run Xinhua news agency reported.

The launch occurred at 7:18 a.m. Beijing time Friday, and the 184-foot-tall (56-meter) Long March 3B turned to the southeast from Xichang, dropping its four strap-on liquid-fueled boosters and core stage to fall back to Earth around two-and-a-half minutes after liftoff.

Dramatic video published on Chinese social media channels appeared to show a piece of the Long March 3B rocket plummeting back to the ground downrange from the Xichang space base, then exploding on impact.

Another video apparently shows the burning wreckage of a booster surrounded by onlookers in Guangxi province, according to a GB Times report.

China’s primary launch sites were constructed in the Cold War era in well-defended inland areas of the country, forcing rockets launched from those locations to drop debris on land, GB Times reported. Chinese authorities say they send notices to the public warning of the possibility of falling debris on each launch, but imagery shared on China’s Weibo social media network after some launches in recent years show rocket parts strewn in villages and on roads.

The Long March 3B rocket burns a toxic mixture of hydrazine and nitrogen tetroxide propellants, a hypergolic combination that ignites when the two liquids make contact.

China has a newer launch base on Hainan Island, allowing for trajectories over the ocean.

The satellites launched Thursday were the 26th and 27th to join the Beidou navigation network, but some were test satellites and are no longer operational.

After a four-hour coast, the Yuanzheng upper stage maneuvered the Beidou satellites into a near-circular orbit around 13,700 miles (22,000 kilometers) above Earth, according to U.S. military tracking data. The orbit was tilted 55 degrees to the equator.

The completed Beidou constellation will consist of 27 satellites in medium Earth orbits, five in geostationary-type orbits around 22,300 miles (36,800 kilometers) over the equator, and three in inclined geosynchronous orbits that oscillate north and south of the equator.

Named for the Chinese word for the Big Dipper constellation, the Beidou constellation achieved an initial operating capability with coverage over the Asia-Pacific region in 2012. Development of the Beidou program began in 1994.

When complete, the Beidou system will join the U.S. Air Force’s Global Positioning System, Russia’s Glonass satellite network, and Europe’s Galileo fleet — which is still being deployed — as the world’s four navigation services with global reach.

The third-generation satellites now being launched by China feature higher-performance rubidium and hydrogen atomic clocks, inter-satellite links, improved spatial signal accuracy, better compatibility with other countries’ navigation satellites, and offer search-and-rescue services, according to a Chinese government release published on the Beidou program’s official website.

Chinese officials aim to have 30 Beidou satellites operational by 2020, enough to offer independent global navigation services.

Up to 16 additional Beidou spacecraft are scheduled for launch by the end of 2018, according to Yang Changfeng, chief designer of the Beidou system.

The launches planned for this year will be sufficient for the Beidou fleet to provide navigation coverage over China and its neighbors, Yang said in an interview posted on the Beidou program’s official government website. The Beidou system achieved an initial operating capability over the Asia-Pacific in 2012.

“The intensive launches will pose a great challenge. We must exercise strict control over quality specifications to ensure each of them is a success,” Yang said.

The Beidou satellites are designed to be interoperable with U.S., Russian and European navigation networks.

“(The) Beidou system is China’s Beidou, but also the world’s Beidou,” Yang said.

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Follow Stephen Clark on Twitter: @StephenClark1.


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