Monday, November 19, 2018

Long March 3B Orbits Another BeiDou-3 Satellite Duo

Long March 3B launch with BeiDou-3 M17 and M18 satellites on November 19, 2018. Photo Credit: Xinhua/Ju Zhenhua

Using its long-serving Long March 3B rocket, China orbited on Monday, November 19 (local time), another pair of BeiDou-3 spacecraft for the country’s homegrown satellite navigation system. This is the eight time this year when Beijing launches BeiDou-3 duo to replenish its navigation network in space.

Liftoff took place at 2:07 a.m. local time (18:07 GMT November 18 / 1:07 p.m. EST November 18) from the Xichang Satellite Launch Center (XSLC) located in China’s Sichuan Province.

Very little information was revealed by Chinese media about pre-launch preparations. While the date of the launch was known, the exact time of the liftoff remained undisclosed. Only brief notice to airmen (NOTAM) issued on November 16 offered some indications when exactly the launch would take place.

Success of the mission was confirmed by the state-owned Xinhua press agency, nearly five hours after liftoff.

“China sent two new satellites of the BeiDou Navigation Satellite System (BDS) into space on a Long March 3B carrier rocket from the Xichang Satellite Launch Center in Sichuan Province at 2:07 a.m. Monday,” a brief press release issued by Xinhua reads.

The two satellites, designated BeiDou-3 M17 and M18, were inserted into a medium-Earth orbit (MEO) at an altitude of some 13,360 miles (21,500 kilometers) with an inclination of approximately 55.5 degrees. In order to get this orbital spot, the flight of the spacecraft duo lasted at least three hours.

BeiDou-3 M17 and M18 were developed by the Innovation Academy for Microsatellites of the Chinese Academy of Sciences (CAS). Both spacecraft are based on a newly-developed dedicated satellite bus with phased array antenna for navigation signals and a laser retroreflector.

Each BeiDou-3 MEO satellite weighs about one metric ton, has two deployable solar arrays and is designed to be operational for about 12 years. The dimensions a spacecraft of this type measure: 7.38 by 3.28 by 4.0 feet (2.25 by 1.0 by 1.22 meters).

Named after the Chinese term for the plough or the Big Dipper constellation, the BeiDou (BDS) project was formally launched in 1994. The first BeiDou satellite was sent aloft in 2000. By 2012, a regional network had already begun to take shape, which provided positioning, navigation, timing, and short message services in China as well as several other Asian countries. The first BeiDou-3 satellite was launched in March of 2015.

With the launch of BeiDou-3 M17 and M18, China completes basic navigation system of BDS. The two newly orbited satellites will work with 17 other BeiDou-3 spacecraft already in space to provide services for countries participating in the Belt and Road initiative by the end of this year.

"This is a key step for BDS developing from a domestic Chinese system to a regional and then a global navigation system," said Yang Changfeng, chief designer of the BeiDou system.

In general, China intends to have the BeiDou-3 constellation consisting of some 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. By the end of 2020, Beijing expects that the system should become global, providing high-precision, reliable positioning, navigation and timing services anywhere in the world.

The three-stage Long March 3B rocket is 180 feet (55 meters) tall and capable of sending up to 12 metric tons of payload into low-Earth orbit (LEO) or five metric tons of cargo into a geostationary transfer orbit (GTO). For the launch of BeiDou-3 M17 and M18, this rocket was equipped with a Yuanzheng-1 (YZ-1) upper stage.

Monday’s launch marked the 291st mission of the Long March rocket series and the 33rd launch conducted by China in 2018.

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