Long March 2D lofts Gaofen-6

by Rui C. Barbosa

China launched a new remote sensing satellite called Gaofen-6 on Saturday from the Jiuquan Satellite Launch Center. Launch took place at 4:13 UTC from the LC9 launch complex using a Long March-2D – Chang Zheng-2D – rocket.

The new satellite is similar to the first Gaofen satellite launched on April 2013, carrying a one 2 meter panchromatic camera, an 8 meter multi-spectral camera and one 16m multispectral medium-resolution and wide-view camera.

The Gaofen civilian high-resolution remote sensing satellites (gao fen = high-resolution) are part of a program that is one of the 16 main programs announced by the State Council in a 15 year plan of Chinese national scientific and technology programs between 2006 and 2020.

This program will become the main civilian Earth observation project of China in the next years, combining the use of satellites as well as airplanes and even stratosphere balloons.

A GF-6 overview found on Chinese Social media

The program was started in 2010 and at least 14 satellites are planned, forming a near-real-time, all-weather, global surveillance network for agricultural planning, disaster relief, environment protection, and security purposes.

In May 2010, China officially initiated the development China High-Resolution Earth Observation System (CHEOS), which is established as one of the major national science and technology projects. The Earth Observation System and Data Center of China National Space Administration (EOSDC-CNSA) is responsible for organizing the construction of the CHEOS.

The Earth Observation System and Data Center, China National Space Administration was established in Mar 2010. The Center is principally responsible for organizing and implementing as well as managing CHEOS. It is also responsible for EO application services, commercial development, technology consultant and international cooperation.

By following an arrangement of integral observation from space, air and ground, the CHEOS develops space-based system, near space system, aerial system, ground system and application system as a whole to materialize earth observation at high temporal, spatial and spectral resolution, which is now in smooth progress. Overall, to meet the strategic demands of the national economic development and social progress.

The initial plan presented five satellites. Gaofen-1 employs a CAST2000 bus, configured with one 2 meter panchromatic / 8 meter multi-spectral camera and one 16m multispectral medium-resolution and wide-view camera. The satellite realizes an integration of imaging capacity at medium and high spatial resolution and with large swath, with a designed lifespan of over 5 years. It was launched on April 26, 2013.

Gaofen-2 employs CS-L3000A bus, configured with one 1 meter panchromatic/4m multi-spectral camera, with a designed lifespan of over 5 years. The satellite was launched on August 19, 2014.

Gaofen-3 employs CS-L3000B bus, configured with multi-polarized C band SAR at meter-level resolution, with a designed lifespan of 8 years. Gaofen-3 was launched on August 9, 2016.

Gaofen-4 is China’s first geosynchronous orbit remote sensing satellite featuring a visible light and infra-red staring optical imager with common optical system. The optical resolution is better than 50 meters, while the infrared resolution is better than 400 meters.


GF-4 can provide an imaging area of 7,000 km × 7,000 km with individual scene covering an area of 400 km × 400 km, and with capacity for high temporal resolution remote sensing monitor at minute-level. The satellite was launched on December 28, 2015 – from the Xichang Satellite Launch Center using a Long March-3B/G2.

Gaofen-5 is configured with six payloads, including a VIS and SWIR (Shortwave Infrared) hyperspectral camera, spectral imager, greenhouse gas detector, atmospheric environment infrared detector at very high spectral resolution, differential absorption spectrometer for atmospheric trace gas, and a multi-angle polarization detector.

Gaofen-5 was launched on May 8, 2018.

Charing the ride to orbit with Gaofen-6 was the Luojia-1 CubeSat. This is a CubeSat-6U sized earth observation satellite built by the Wuhan University that is a prototype for a future 60-80 earth observation satellite constellation. Luojia-1 features an imager with 100 meter ground resolution.

The Long March-2D (LM-2D) launch vehicle is a two-stage rocket developed by the Shanghai Academy of Spaceflight Technology. With storable propellants is mainly used to launch a variety of low earth orbit satellites.

The development of LM-2D was started in February 1990. From 2002, to meet the demand of SSO satellites, the payload fairing of 3350mm in diameter and attitude control engine for the second stage have been successfully developed; and the discharge of remaining propellant and de-orbit of the second stage have been realized. This launcher is mainly used for launching LEO and SSO satellites.

It is characterized by high reliability, wide application and mature technology.

The LM-2D can launch a 1,300 kg cargo in a 645 km SSO. The rocket is 41.056 meters long and the first, second stages and payload fairing are all 3.35 meters in diameter.

The first stage is the same of the Long March-4.

The Long March used for this mission

The second stage is based on LM-4 second stage with an improved equipment bay. Lift-off mass is 232,250 kg, total length 41,056 meters, diameter 3.35 meters and fairing length 6.983 meters. At launch, it develops 2961.6 kN engine thrust.

The first stage has a 27.910 meter length with a 3.35 meter diameter, consuming 183,200 kg of N2O4 / UDMH (launch mass of the first stage is 192,700 kg). Equipped with a YF-21C engine capable of a ground thrust of 2,961.6 kN and a ground specific impulse of 2,550 m/s. Burn time is 170 seconds.

The second stage has a 10.9 meter length with a 3.35 meter diameter, launch mass of 39,550 kg and consuming 45,550 kg of N2O4 / UDMH. Equipped with a YF-24C cluster engine with a main engine vacuum thrust of 742.04 kN and a vernier engine with a vacuum thrust of 47.1 kN (specific impulses of 2,942 m/s and 2,834 m/s, respectively).

The LM-2D can use two types of fairings depending on the cargo. Type A fairing has a 2.90 meters diameter (total launch vehicle length is 37.728 meters) and Type B fairing with a diameter of 3.35 meters – total launch vehicle length is 41.056 meters.

Long March 2D launch – photo from Chinese media.

Launch profile of the Long March-2D starts with engine ignition at 1.2 seconds before lift-off. Pitch over maneuver happens at 12 seconds into the flight and the end of the first stage ignition occurs at two minutes 33 seconds. Stage separation and second stage ignition occur one second latter. At 3 minutes 34 seconds the two parts of the fairing separate from the second stage.

Second stage main engine cut-off takes place at 4 minutes 21 seconds and second stage Vernier engines cut-off takes place at 9 minutes and 10 seconds. Nominally payload separation takes place three seconds later.

The first launch of the LM-2D was on August 9th, 1992 from the Jiuquan Satellite Launch Center orbiting the Fanhui Shei Weixing FSW-2-1 (22072 1992-051A) recoverable satellite.

The Jiuquan Satellite Launch Center, in Ejin-Banner – a county in Alashan League of the Inner Mongolia Autonomous Region – was the first Chinese satellite launch center and is also known as the Shuang Cheng Tze launch center.

The site includes a Technical Centre, two Launch Complexes, Mission Command and Control Centre, Launch Control Centre, propellant fuelling systems, tracking and communication systems, gas supply systems, weather forecast systems, and logistic support systems.

The Launch Site – Photo via Chinese Media

Jiuquan was originally used to launch scientific and recoverable satellites into medium or low earth orbits at high inclinations. It is also the place from where all the Chinese manned missions are launched.

The LC-43 launch complex, also known as South Launch Site (SLS) is equipped with two launch pads: 91 and 94. Launch pad 91 is used for the manned program for the launch of the Long March-2F launch vehicle (Shenzhou and Tiangong). Launch pad 94 is used for unmanned orbital launches by the Long March-2C, Long March-2D and Long March-4C launch vehicles.

Other launch zones at the launch site are used for launching the Kuaizhou, Kaituo and the Long March-11 solid propellant launch vehicles.

The first orbital launch took place on April 24, 1970 when the Long March-1 rocket launched the first Chinese satellite, the Dongfanghong-1 (04382 1970-034A).

Next in line for China will be the launch of a new meteorological satellite from the Xichang Satellite Launch Center. The Fengyun-2H satellite will be orbited by a Long March-3A launch vehicle.

Also is June is expected the launch of a new pair of navigation satellites from the Xichang Satellite Launch Center.

China is also preparing the launch of the PRSS-1 (Pakistan Remote Sensing Satellite) that will take place from the Taiyuan Satellite Launch Center using a Long March-2C/SMA, together with the PakTES-1 satellite.

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