Wednesday, March 30, 2016

China Successfully Launches Its Newest BeiDou Navigation Satellite

A Long March 3A rocket carrying the 22nd satellite in the BeiDou Navigation Satellite System lifts off from Xichang Satellite Launch Center, southwest China's Sichuan Province, Mar. 29, 2016. Photo Credit: Xinhua/Wang Yulei

China has successfully launched on Tuesday, Mar. 29, its newest addition for the country’s homegrown BeiDou navigation satellite system. The spacecraft, designated Beidou-2 IGSO-6 was lifted off on top a Long March 3A at 4:11 p.m. EDT (20:11 GMT) from the Launch Complex 2 at the Xichang Satellite Launch Center, located in southwest China's Sichuan Province.

The launch was shrouded in secrecy and no information was available before liftoff. According to Gbtimes.com, first indication of the launch came from Chinese social media. The state-run Xinhua news agency confirmed the liftoff couple of hours later.

The satellite separated from the launch vehicle nearly half-hour after blastoff. It is expected to reach an inclined geosynchronous orbit (IGSO) at an altitude of about 22,000 miles (35,400 km) with an inclination of about 55 degrees.

Xinhua reports that the spacecraft, after entering its designed work orbit and finishing in-orbit testing, will join other BeiDou satellites already in orbit and improve the stability of the system. It will prepare the network to offer global coverage.

Weighing slightly over two metric tons, Beidou-2 IGSO-6 has dimensions of 7.38 by 3.28 by 7.21 feet (2.25 by 1.0 by 2.2 meters). It is based on the DFH-3 bus designed by the China Academy of Space Technology (CAST), that can host payloads up to 440 lbs. (200 kg). DFH-3 is fitted with a phased array antenna for the transmission of navigation signals, an S- and L-Band dish antenna, a C-Band ranging antenna and a laser retroreflector. The satellite features also two deployable solar arrays and is expected to be operational for up to eight years. 

The new satellite belongs to the Phase II of the BeiDou and is the 22nd spacecraft overall in the series. Phase II is used to replenish the currently operating regional system and ensure it remains operational until the global system will be started. This phase began offering services for the Asia-Pacific region in December 2012. The deployment of the third phase commenced in 2015 and is expected to reach its full operational capability by 2020.

The BeiDou Navigation Satellite System has been operating since 2000. It is composed of three parts: the space section, the ground section and the user section. The space section contains five geostationary orbit satellites and 30 non-geostationary orbit satellites. The ground section consists of a certain number of stations: including the main control stations, the injection stations and the monitoring stations. The user section includes terminators of BeiDou system, and some compatible with other navigation satellite system.

BeiDou is very similar to that provided by GPS and European Galileo and is designed to achieve similar performances. The network will be dual use, based on a civilian service that will provide an accuracy of about 33 feet (10 meters) in the user position, 0.45 mph (0.2 m/s) on the user velocity and 50 nanoseconds in time accuracy; as well as the military and authorized user’s service, providing higher accuracies. The restricted service will have a tracking accuracy of 0.33 feet (0.1 meters).

The 172 feet (52 meters) tall, 11 feet (3.35 meters) wide Long March 3A rocket that was used in Tuesday’s mission is a three-stage launch vehicle, designed to deliver up to 2.6 metric tons of payload into a geostationary transfer orbit (GTO) and up to 8.5 metric tons to low-Earth orbit (LEO). The rocket has a launch mass of approximately 241 metric tons. Its maiden launch was conducted on Feb. 8, 1994. The booster is usually used to place communications satellites and BeiDou navigation spacecraft into orbit.

The first stage and second stage of the rocket use storable propellants, like unsymmetrical dimethyl hydrazine (UDMH) and nitrogen tetroxide (N2O4). The third stage employs cryogenic propellants, like liquid hydrogen (LH2) and liquid oxygen (LOX).

Tuesday’s mission was the 225th launch of the Long March rocket and the third orbital flight of this booster this year. It was also the third liftoff from Xichang in 2016.

This year, China intends to carry out more than 20 space missions. The country’s next launch is currently planned for June, when a Long March 7 rocket is slated to conduct its maiden flight. China could also launch more announced missions until June.

The nation also plans to return to the business of human space flight this year. Shenzhou-11, a planned crewed mission, is slated to lift off from the Jiuquan Satellite Launch Center and dock with China’s second planned space station, Tiangong-2, which should be in orbit by the time the crew’s Shenzhou spacecraft is sent aloft. The exact launch dates for these missions have yet to be released.

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