China churns out yet another launch with flight of BeiDou-2 I7 navigation satellite
On Monday, July 9, China utilized a Long March 3A rocket to send the BeiDou-2 I7 satellite on its way to orbit. The flight marked the second successful launch in less than two days – and added another spacecraft to the nation’s homegrown BeiDou satellite navigation system.
The launch of the BeiDou-2 I7 spacecraft was conducted some 17 hours after the country’s space agency used a Long March 2C rocket to deliver a dual payload for Pakistan.
The launch of Long March 3A took place at 20:58 GMT (4:58 p.m. EDT) from Launch Complex 2 located at the Xichang Satellite Launch Center (XSLC) in China’s Sichuan Province.
The mission had originally been slated to get underway on July 19 but apparently Beijing decided to conduct the launch ten days earlier than scheduled. As usual, Chinese media remain silent about the cause of this reschedule.
The details about pre-launch preparations and the flight itself were also under an informational embargo. What is known is that after launch, the Long March 3A rocket started its short vertical climb before turning southeasterly to fly over mainland China, toward the South China Sea. The whole flight most likely lasted a few hours as the payload was delivered into an inclined geosynchronous orbit (IGSO).
State-run Xinhua press agency confirmed the launch within two hours after liftoff.
“China sent a new Beidou navigation satellite into orbit on a Long March 3A rocket from the Xichang Satellite Launch Center, in the southwestern Sichuan Province, at 4:58 a.m. Tuesday [local time],” the agency informed.
Developed by the China Academy of Space Technology (CAST), BeiDou-2 I7 is based on the DFH-3 satellite bus. The spacecraft features two deployable solar arrays, a phased array antenna for navigation signals and a laser retroreflector. The satellite is designed to be operational for some eight years and will reside in IGSO at an altitude of about 22,232 miles (35,780 kilometers), inclined 55.1 degrees.
BeiDou-2 I7 belongs to the second generation of BeiDou satellites. Although China lately launches spacecraft representing the third generation of the system (BeiDou-3), upgraded BeiDou-2 are still being sent to space to replace the old ones nearing the end of their operational life.
“The launch of a backup Beidou-2 satellite will ensure the system’s continuous and stable operation,” said Yang Hui, chief designer of the Beidou-2 series.
Yang Hui went on to note that BeiDou-2 I7 is not a simple repeat of previous satellites, but has been upgraded to improve its reliability, adding that the spacecraft carries a rubidium clock. This device is considered to be key to the accuracy of BeiDou-2 I7’s positioning and timing.
The previous backup BeiDou-2 satellite, named Compass-G7, was launched on June 12, 2016.
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.
“In the past five years, the system has helped rescue more than 10,000 fishermen. More than 40,000 fishing vessels and around 4.8 million commercial vehicles in China have been equipped with BeiDou,” said BeiDou spokesperson Ran Chengqi.
The 172-foot (52-meter) tall, 11-foot (3.4-meter) wide Long March 3A rocket that was used for Monday’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 launch of BeiDou-2 I7 marks the 280th flight of the Long March rocket series and the 20th mission that China has carried out in 2018.
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