China successfully launches its newest BeiDou navigation satellite
On Tuesday, March 29, China successfully launched the newest addition to the country’s homegrown BeiDou Navigation Satellite System. The spacecraft, designated Beidou-2 IGSO-6, lifted off atop a Long March 3A rocket 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, the first indication of the launch came from Chinese social media. The state-run Xinhua news agency confirmed liftoff of the rocket a couple of hours later.
The satellite separated from the launch vehicle nearly half-an-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.
After entering its designed work orbit and finishing in-orbit testing, Xinhua reports that the spacecraft 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 ft × 3.28 ft × 7.21 ft (2.25 m × 1.0 m × 2.2 m). It is based on the DFH-3 bus designed by the China Academy of Space Technology (CAST), and it can host payloads of 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 also features two deployable solar arrays and is expected to be operational for up to eight years.
The new satellite is a constituent of the Phase II constellation of the BeiDou Navigation Satellite System (BDS) and is the 22nd spacecraft overall in the series. Phase II will serve to replenish the currently operating regional system and ensure that it remains operational until the global system is initiated. This 2nd generation BDS 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 BDS has been operating since 2000. It is composed of three parts: the space section, the ground section, and the user section. The space section comprises five geostationary orbit satellites and 30 non-geostationary orbit satellites. The ground section consists of a certain number of stations: the main control stations, the injection stations, and the monitoring stations. The user section includes terminals of the BeiDou system and some compatible with other navigation satellite systems.
BeiDou is very similar to the navigation system provided by GPS and the European Galileo, and it is designed to achieve similar performances. The network will be dual use: a free service for civilians, and a licensed service for the Chinese government and military. The civilian service 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. The restricted military and authorized users’ service will provide higher tracking accuracies of 0.33 feet (0.1 meters).
The 172 feet (52 meters) tall, 11 feet (3.35 meters) wide Long March 3A rocket, which was used for Tuesday’s mission, is a three-stage launch vehicle. It is 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; in this case, unsymmetrical dimethyl hydrazine (UDMH) and nitrogen tetroxide (N2O4). The third stage employs the cryogenic propellants liquid hydrogen (LH2) and liquid oxygen (LOX).
Tuesday’s mission was the 225th launch of a Long March rocket and the third orbital flight of the 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 may also announce the launch of further missions until the end of June.
The nation also plans to return to the business of human space flight this year. Shenzhou-11, a proposed 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.
Video Courtesy of CCTV+
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