(SpaceFlightInsider)– China successfully launched a Long March-3B rocket carrying two BeiDou-3 spacecraft for its satellite navigation system. The booster took to the skies at 1:56 p.m. EDT (17:56 GMT) March 29, 2018, from the Xichang Satellite Launch Center in China’s Sichuan province.
Powered by its first stage and four liquid rocket boosters, the Long March-3B completed a short vertical ascent after liftoff before pitching toward the southeast in order to fly over the island of Hainan, toward South China Sea.
Although China keeps the details about its missions under tight wraps, it is assumed that the whole flight should have lasted several hours as the rocket was tasked with inserting the payload into a medium-Earth orbit (MEO).
Thursday’s mission was initially targeted for March 12, but was postponed by 2.5 weeks. Beijing, however, has not disclosed why the flight was rescheduled.
The two passengers of the mission, BeiDou-3 M5 and BeiDou-3 M6, are based on a newly-developed dedicated satellite bus. Each have a mass of about one metric ton and both satellites have two deployable solar arrays and were designed to be operational for about 12 years. Once deployed, the duo will offer services from MEO at an altitude of some 13,360 miles (21,500 kilometers), with an inclination of approximately 55.5 degrees.
The BeiDou (BDS) project, named after the Chinese term for the plough or the Big Dipper constellation, was formally launched in 1994. The first BeiDou satellite was sent aloft in 2000 and by 2012 a regional network had already begun to take shape, which provided positioning, navigation, timing, and short message services in China and several other Asian countries.
BeiDou-3 M5 and BeiDou-3 M6 represent the third phase of the BDS system and it is the final stage of the establishment of a Chinese space-based navigation architecture. The constellation should consist of 27 BeiDou-3M satellites in MEO, five BeiDou-3G satellites in a geostationary orbit, and three BeiDou-3I satellites in an inclined geosynchronous satellite orbit. The first BeiDou-3 satellite was launched in March of 2015.
BeiDou as a constellation is expected to provide navigation and positioning services to countries under the “Belt and Road Initiative” (more than 60 countries in Asia, Europe, Oceania and East Africa) by late 2018.
“The BeiDou system not only belongs to China, but the whole world,” said Yang Changfeng, chief designer of the BeiDou system, in a Xinhuanet report.
The three-stage Long March-3B rocket that was employed for this flight is a 180-foot (55-meter) tall launch vehicle that is capable of sending up to 12 metric tons of payload to low-Earth orbit or five metric tons of cargo into a geostationary transfer orbit. For some launches, such as this one, this rocket can be equipped with a Yuanzheng-1 upper stage.
This was the ninth Chinese launch so far in 2018 and the third Long March-3B. The next rocket flight from the Asian country is expected to be on April 21 when it lofts another Long March-3B with the Apstar 6C communications satellite. However, China has been known to fly many of its missions unannounced.
The launch of three BeiDou satellites in February 2018. Video courtesy of SciNews