Chinese Long March 3B rocket successfully launches Gaofen-4 Earth observation satellite
China has closed out the 2015 launch manifest with the flight of its most sophisticated Earth-observation satellite, Gaofen-4. A Chinese Long March 3B rocket was used to deliver the spacecraft to orbit. The booster blasted off at 11:04 a.m. EST (16:04 GMT) on Monday, Dec. 28, from the Launch Area 2 at the Xichang Satellite Launch Center, located in the southwestern Sichuan province.
The Long March 3B launch vehicle fired its four boosters and the central core stage to start its standard ascent mission. The boosters were jettisoned about two minutes and 20 seconds into the flight and the rocket moved into a southeasterly direction over the Pacific Ocean. The Gaofen-4 satellite separated from the launch vehicle approximately 26 minutes after liftoff and was delivered into a geostationary orbit (GEO) at an altitude of 22,370 miles (36,000 km).
A Long March 3B rocket launches Gaofen-4 satellite on Dec. 28, 2015. Photo Credit: 81.cn/Weibo via 9ifly.cn
The exact date of the mission was kept under wraps by Chinese officials. A confirmation of the successful launch was released by the state-run media nearly three hours after liftoff.
Weighing 4.6 metric tons, Gaofen-4 features a hexagonal platform with two two-panel solar arrays. The satellite is equipped with a visible light and infrared staring optical imager with a common optical system. The ground resolution for the visible light imager is 164 feet (50 m) and for the infrared payload is 1,312 feet (400 m). It can provide an imaging area of 4,350 by 4,350 miles (7,000 by 7,000 km) with individual scene covering an area of 248 by 248 miles (400 by 400 km), and with a capacity for high temporal resolution remote sensing monitor at minute-level. The satellite is expected to be operational for eight years.
Gaofen-4 can “see” an oil tanker on the sea with a huge CMOS camera, reaching the best imaging level among global high-orbit remote sensing satellites, according to Li Guo, chief designer of the satellite.
According to Tong Xudong, the chief designer of the Gaofen project at the State Administration of Science, Technology and Industry for National Defense (SASTIND), the satellite will be used for disaster prevention as well as relief, surveillance of geological disasters and forest disasters, and meteorological forecast. The spacecraft is China’s first geosynchronous orbit HD optical imaging satellite and, according to the Chinese, the world’s most sophisticated HD geosynchronous orbit remote sensing satellite.
“The main breakthrough of Gaofen-4 is it will realize high-precision survey and image synthesis, long-distance imaging and data processing and transmission,” said Li Bin of the Department of International Relations at Tsinghua University.
However, Western analysts believe that the Gaofen-4 will be also used to detect U.S. aircraft carriers in China’s neighborhood. The spacecraft could also be a part of a network that will work together to locate, target, and destroy aircraft carriers and destroyers.
The first Gaofen satellite was launched in April of 2013 and it is expected that the Gaofen project will see some seven high-definition Earth-observation satellites launched before 2020.
The Gaofen satellites are part of the China High-Resolution Earth Observation System (CHEOS). The system plans to provide real-time, all-day global Earth observation in any weather. The Earth Observation System and Data Center of China National Space Administration (EOSDC-CNSA) is responsible for organizing the construction of CHEOS.
China has carried out an array of launches in 2015 – with little sign of slowing in the coming year. Photo Credit: Daderot
The CHEOS program comprises the elements of the space-borne system, the near-space system, aerial system, the ground system, and application system as a whole to realize Earth observation at high temporal, spatial, and spectral resolution. The primary data users of the program are the Ministry of Land and Resources, the Ministry of Environmental Protection, and the Ministry of Agriculture.
The three-stage Long March 3B rocket used in Monday’s flight is currently the most powerful Chinese booster in service. The 180-foot (55-meter) tall booster is capable of launching up to 12 metric tons of payload to low-Earth orbit (LEO) or 5 metric tons of cargo to a geostationary transfer orbit (GTO).
The 3B/E version that was employed for the mission is an enhanced variant of the rocket, featuring an enlarged first stage and boosters. This version was brought into service in 2007 to increase the rocket’s GTO cargo capacity and lift heavier GEO communications satellites.
Monday’s mission was the 222th flight of the Long March rocket series and the 34th flight overall for the 3B version. It’s also the 9th launch from Xichang this year.
With the Gaofen-4 launch, China wraps up a very busy year in terms of sending payloads to orbit. In 2015, the country carried out 19 missions into the blackness of space – according to the Chinese, all of them were successful. In comparison, the U.S. conducted 20 launches and Russia 29 (26 successful) in 2015.
In 2016, China plans to return to human space flight. Shenzhou-11, a planned crewed mission is slated to lift off from the Jiuquan Satellite Launch Center and dock with China’s upcoming second space lab, Tiangong-2, which should be on 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+
Tomasz Nowakowski
Tomasz Nowakowski is the owner of Astro Watch, one of the premier astronomy and science-related blogs on the internet. Nowakowski reached out to SpaceFlight Insider in an effort to have the two space-related websites collaborate. Nowakowski's generous offer was gratefully received with the two organizations now working to better relay important developments as they pertain to space exploration.
