China launches Long March 3B rocket with Beidou-3 navigation satellite
On Tuesday, Sept. 29, 2015, China successfully launched its third-generation navigation satellite into orbit. The BDS I2-S satellite lifted off atop the country’s Long March 3B/E launch vehicle at 7:13 p.m. EDT (23:13 GMT) from Launch Complex 3 at the Xichang Satellite Launch Center. It is the 20th satellite for the Chinese Beidou Navigation Satellite System (BDS).
The rocket completed a short vertical ascent before aligning itself on a southeasterly trajectory toward an inclined geosynchronous satellite orbit (IGSO). It took the Chinese media more than an hour to acknowledge the launch.
The BDS I2-S satellite represents the third phase of the BDS system (Beidou-3). It is the final stage of te establishment of a Chinese space-based navigation architecture. The constellation will consist of 27 Beidou-3M satellites in medium-Earth orbit (MEO), five Beidou-3G satellites in geostationary orbit (GTO), and three Beidou-3I satellites in IGSO.
The BDS I2-S spacecraft, which weighs about 4.5 metric tons, uses a new bus that includes a phased array antenna for navigation signals and a laser retroreflector. The Chinese satellite that was launched on Tuesday featured a hydrogen maser-based atomic clock. A series of tests related to the clock and a new navigation-signal system will be undertaken, according to a statement from the Xichang Satellite Launch Center. The satellite has an operational lifespan of 10 years.
The satellite has two navigation payloads: the Beidou-3 Radio Navigation Satellite Service (RNSS) and the heritage Radio Determination Satellite Service that provides compatibility with existing Beidou-1 terminals on the ground. RNSS is very similar to the U.S. GPS and European Galileo systems and is designed to achieve similar performances.
The first Beidou-3 satellite was launched in March 2015; the next two were delivered into orbit in July 2015.
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.
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/E rocket used in Tuesday’s flight is currently the most powerful Chinese launch vehicle. The 180-foot (55-meter) tall booster is capable of launching up to 12 metric tons of payload into low-Earth orbit or 5 metric tons of cargo into GTO. For the Sept. 29 launch, the rocket was equipped with a Yuanzheng-1 upper stage.
Thanks to this successful flight, China wraps up a record-breaking month in the country’s history of spaceflight. In September, Chinese rockets have conducted five orbital launches in the span of only 18 days. China has already performed nine space missions this year (2015), including the debuts of the Long March 6 and 11 rockets. At present, the nation plans six more launches. The next flight is scheduled for Oct. 7, 2015, when a Long March 2D rocket will loft three Jilin-1 Earth observation satellites.
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