Ground crews at the Xichang launch center China are preparing to fire a Long March 3B rocket into orbit Tuesday to complete the deployment of the Beidou navigation fleet, a project approved by the Chinese government in 1994 to end reliance on the U.S. military’s GPS network.
The Long March 3B rocket is set to loft China’s final Beidou navigation satellite toward a position in geostationary orbit more than 22,000 miles (nearly 36,000 kilometers) over the equator.
Liftoff of the liquid-fueled Long March 3B launcher is scheduled for a window opening at 0211 GMT Tuesday (10:11 p.m. EDT Monday), or 10:11 a.m. Beijing time, according to Chinese government officials.
Chinese state media and government agencies announced the Long March 3B rocket’s launch ahead of time, a break from the standard practice of not publicizing the launch of space missions before they take off, other than customary airspace and maritime notices warning pilots and mariners to steer clear of booster drop zones.
Some high-profile Chinese space missions, such as launches of astronauts and flights of the country’s heavy-lift Long March 5 rocket, have been similarly publicized ahead of time.
The final Beidou satellite to round out the Chinese navigation network was built by the China Academy of Space Technology. Based on the DFH-3B satellite platform, the spacecraft weighs more than 10,000 pounds, or about 4,600 kilograms, filled with propellants for maneuvers in orbit.
China designed the Beidou Navigation Satellite System, or BDS, as an independent version of the GPS network, providing Chinese military and civilian users with a home-grown system in case the U.S. military interrupts GPS signals during a conflict. Like the GPS network, Russia’s Glonass fleet and Europe’s Galileo navigation constellation, the Beidou system is designed for global service.
The Long March 3B rocket launch Tuesday will complete the deployment of the Beidou program’s third-generation, or BDS-3, satellite network.
It will be the 35th BDS-3 satellite launched since 2015 — including test and validation satellites — and the 59th Beidou spacecraft launched since 2000.
The Beidou network, named for the Chinese word for the Big Dipper constellation, includes satellites positioned in three different types of orbits. The Beidou system needs at least 30 satellites operating at any one time for uninterrupted global navigation service.
In December, China launched the last of 24 operational satellites into a medium-altitude orbit more than 13,000 miles (21,000 kilometers) above Earth, similar to the orbits used by GPS, Glonass and Galileo satellites.
But unlike the other global navigation systems, the fully-operational Beidou network includes six spacecraft in geosynchronous orbits, with three permanently over the equator and three others in inclined orbits that swing north and south of the equator during each 24-hour orbit.
China launched three satellites into inclined geosynchronous orbits last year, and the spacecraft set for launch Tuesday is the third of three to be permanently stationed over the equator.
The first four Beidou satellites broadcast positioning and timing signals over China. The second phase of the Beidou system, known as BDS-2, was completed in 2012 to provide navigation services over the broader Asia-Pacific region.
As of Monday, China’s Beidou network had 44 operational spacecraft, including BDS-2 and BDS-3 satellites.
In addition to military uses, China says Beidou services are used in transportation, agriculture, fishing, and disaster relief. More than 70 percent of smartphones in China are equipped to receive Beidou signals, and more than half of countries worldwide are using Beidou services, according to the state-run Xinhua news agency.
The satellite scheduled for launch Tuesday is expected to enter operational service in a few months, once its maneuvered from the Long March 3B rocket’s elliptical insertion orbit into a circular geostationary orbit above the equator.
“After the global system is completed this year, the BDS can provide satisfactory services to every corner of the world,” said Yang Changfeng, chief designer of the Beidou system, according to Xinhua.
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