Monday, December 28, 2015

Chinese Long March 3B Rocket Successfully Launches Gaofen-4 Earth Observation Satellite

A Long March 3B rocket launches Gaofen-4 satellite on Dec. 28, 2015. Photo Credit: via

China has closed out the year with the launch its most sophisticated Earth observation satellite, Gaofen-4. A Chinese Long March 3B rocket was used to deliver the spacecraft into orbit. The booster blasted off at 12:04 p.m. EDT (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 a 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 was moving into the south-east direction over the Pacific Ocean. The Gaofen-4 satellite separated from the launch vehicle approximately 26 minutes after the liftoff and was delivered into a geostationary orbit (GEO) at an altitude of 22,370 miles (36,000 km).

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 the liftoff.

Weighing 4.6 tons, Gaofen-4 features a hexagonal platform with two two-panel solar arrays. The satellite is equipped in an visible light and infra-red staring optical imager with common optical system. The ground resolution for the visible light imager is 164 feet (50 m) and for the infra-red 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 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 and relief, surveillance of geological disasters and forest disasters, and meteorological forecast. It is China's first geosynchronous orbit HD optical imaging satellite and 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 Gaofen-4 will be also used to detect US aircraft carriers in China’s neighborhood. The spacecraft could 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 2013. The Gaofen project aims to launch seven high-definition observation satellites 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.

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 rocket in service. The 180-foot (55-meter) tall booster is capable of launching up to 12 metric tons of payload into low-Earth orbit (LEO) or 5 metric tons of cargo into 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 geosynchronous equatorial orbit (GEO) communications satellites.

Monday’s mission was the 222th flight of the Long March rocket series and the 34th liftoff 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 of orbital flights. In 2015, the country carried out 19 space missions, all of them successful. In comparison, the US has conducted 20 orbital launches but only 18 ended in success. Russia remains the leader, conducting 29 orbital missions (26 successful) in 2015.

In 2016, China plans to return to human spaceflight. Shenzhou-11, a planned crewed mission will lift off from the Jiuquan Satellite Launch Center and dock with China’s upcoming second space lab, Tiangong-2, which will be launched earlier. However, exact dates for these missions haven’t been released yet.

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