China launched a new remote sensing satellite on November 27 from the Taiyuan Satellite Launch Center, Shanxi Province. Launch of Gaofen-12 took place at 23:52 UTC from the LC9 launch complex using the Long March-4C (Y24) – Chang Zheng-4C – rocket.
The new Earth observation satellite is equipped with a high-resolution Earth observation system. It uses a microwave remote sensing system with ground cell resolution up to the sub-meter level, to be mainly used in land census, urban planning, land rights, road network design, crop estimation and disaster prevention and mitigation and other fields
The SAST built radar satellite will work together with other Gaofen satellites to form an Earth observation system with high resolution and high positioning accuracy, which will help promote international sci-tech industrial cooperation through data sharing and support the Belt and Road initiative.
Gaofen (“High Resolution”) is a series of civilian Earth observation satellites developed and launched for the state-sponsored program China High-definition Earth Observation System (CHEOS).
In May 2010, China officially initiated the development of the CHEOS system, 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 that is near-real-time, all-weather, global surveillance network consisting of the satellite, stratosphere airships, and aerial observation platforms.
The Earth Observation System and Data Center, China National Space Administration was established in March, 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 is developing a space-based system, near-space system, aerial system, ground system and application system.
This is to create Earth observation at a high temporal, spatial and spectral resolution, which is making good progress.
To meet the strategic demands of the national economic development and social progress, the initial plan involved five satellites.
Gaofen-1 employed 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 integrates imaging capacity at medium and high spatial resolution and with large swath, with a designed lifespan of over five years. It was launched on April 26, 2013.
Gaofen-2 employed a 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.
Designed by CAST (China Academy of Space Technology), Gaofen-3 employs the CS-L3000B bus configured with multi-polarized C-band SAR at meter-level resolution. The satellite had a designed lifespan of eight years and will mainly be used by the State Oceanic Administration (SOA) of China. GF-3 was launched on August 9, 2016.
Gaofen-4 was developed by CAST and is based on the new GEO remote-sensing satellite bus. It has an orbital mass of 4,600 kg, and was designed for a lifespan of 8 years. The satellite was placed into orbit by a Long March-3B launch vehicle from the Xichang Satellite Launch Centre on 29 December 2015.
Gaofen-5 employs SAST5000B bus and is configured with six types of payloads, including visible and short-wave infra hyperspectral camera, spectral imager, greenhouse gas detector, atmospheric environment infrared detector at the very high spectral resolution, differential absorption spectrometer for atmospheric trace gas, and multi-angle polarization detector. It is designed for 8 years and was launched on May 8, 2018, using a Long March-4C rocket from Taiyuan.
A Long March-2D orbited the Gaofen-6 satellite out of Jiuquan on June 2, 2018. This was an optical satellite similar to the Gaofen-1, but using a different instrument suite, consisting of a 2/8 m resolution panchromatic/hyperspectral camera with an image swath of >90 km and a 16 m resolution wide-angle camera with an 800 km image swath. Both cameras use a three-mirror anastigmat telescope. Both covers visible light to NIR bands.
On June 26, 2015, China launched the Gaofen-8 satellite. Developed by the China Aerospace Science and Technology Corporation (CASC), the satellite is part of a civilian program whose aim is to facilitate climate surveying, disaster response, precision agriculture mapping, urban planning and road network design. Its imagery will be mostly used by the Ministry of Land and Resources, the Ministry of Environmental Protection, and the Ministry of Agriculture. The satellite was launched from the Taiyuan Satellite Launch Center using a Long March-4B rocket.
On September 14, 2015, another Gaofen satellite, Gaofen-9, was launched from the Jiuquan Satellite Launch Center, using a Long March-2D. Possibly a civilian version of the Yaogan Weixing-2 (Jianbing-6) satellite, Gaofen-9 will provide sub-meter class resolution optical images for city planning, road network design, land ownership determination purposes.
A Gaofen-1 triplet was launched on March 31, 2017, by a Long March-4C from Taiyuan.
What appears to be a high-resolution optical Earth observation satellite, Gaofen-11, was launched on July 31, 2018, using a Long March-4B launch vehicle from Taiyuan.
On October 4, 2019, a new satellite designated Gaofen-10 was launched using a Long March-4C vehicle from Taiyuan.
Gaofen-7 was launched on November 3, 2019.
The feasibility study of the CZ-4 Chang Zheng-4 began in 1982 based on the FB-1 Feng Bao-1 launch vehicle. Engineering development was initiated in the following year.
📌：Launch media thread!
🚀：Long March 4C
— LaunchStuff (@LaunchStuff) November 28, 2019
Initially, the Chang Zheng-4 served as a backup launch vehicle for Chang Zheng-3 to launch China’s communications satellites.
After the successful launch of China’s first DFH-2 communications satellites by Chang Zheng-3, the main mission of the Chang Zheng-4 was shifted to launch sun-synchronous orbit meteorological satellites. On the other hand, the Chang Zheng-4B launch vehicle was first introduced in May 1999 and also developed by the Shanghai Academy of Space Flight Technology (SAST), based on the Chang Zheng-4.
The rocket is capable of launching a 2,800 kg satellite into low Earth orbit, developing 2,971 kN at launch. With a mass of 248,470 kg, the CZ-4B is 45.58 meters long and has a diameter of 3.35 meters.
SAST began to develop the Chang Zheng-4B in February 1989. Originally, it was scheduled to be commissioned in 1997, but the first launch didn’t take place until late 1999. The modifications introduced on the Chang Zheng-4B included a larger satellite fairing and the replacement of the original mechanical-electrical control on the Chang Zheng-4 with electronic control.
Other modifications were an improved telemetry, tracking, control, and self-destruction systems with smaller size and lighter weight; a revised nozzle design in the second stage for better high-altitude performance; a propellant management system for the second stage to reduce the spare propellant amount, thus increasing the vehicle’s payload capability and a propellant jettison system on the third-stage.
The first stage has a 24.65 meter length with a 3.35 meter diameter, consuming 183,340 kg of N2O4/UDMH (gross mass of the first stage is 193.330 kg). The vehicle is equipped with a YF-21B engine capable of a ground thrust of 2,971 kN and a ground specific impulse of 2,550 Ns/kg. The second stage has a 10.40 meter length with a 3.35 meter diameter and 38,326 kg, consuming 35,374 kg of N2O4/UDMH.
The vehicle is equipped with a YF-22B main engine capable of a vacuum thrust of 742 kN and four YF-23B vernier engines with a vacuum thrust of 47.1 kN (specific impulses of 2,922 Ns/kg and 2,834 Ns/kg, respectively).
The third stage has a 4.93 meter length with a 2.9 meter diameter, consuming 12,814 kg of N2O4/UDMH. Having a gross mass of 14,560 kg, it is equipped with a YF-40 engine capable of a vacuum thrust of 100.8 kN and a specific impulse in a vacuum of 2,971 Ns/kg.
Situated in the Kelan County in the northwest part of the Shanxi Province, the Taiyuan Satellite Launch Center (TSLC) is also known by the Wuzhai designation. It is used mainly for polar launches (meteorological, Earth resources and scientific satellites).
The launch center has two single-pad launch complexes, a technical area for rocket and spacecraft preparations, a communications center, a mission command and control center, and a space tracking center.
The stages of the rocket are transported to the launch center by railway and offloaded at a transit station south of the launch complex. They were then transported by road to the technical area for checkout procedures.
The launch vehicles were assembled on the launch pad by using a crane at the top of the umbilical tower to hoist each stage of the vehicle in place. Satellites were airlifted to the Taiyuan Wusu Airport about 300km away and then transported to the center by road.
The TT&C Centre, also known as Lüliang Command Post, is headquartered in the city of Taiyuan, It has four subordinate radar tracking stations in Yangqu (Shanxi), Lishi (Shanxi), Yulin (Shaanxi), and Hancheng (Shaanxi).