China’s YaoGan Weixing-12 (YG-12) satellite – highly likely to be used for military purposes – has been launched into orbit by a CZ-4B Chang Zheng-4B (Long March 4B) rocket on Wednesday. The launch took place from the Taiyuan Satellite Launch Center at 11:21am local time.
Another Chinese Launch:
Once again, the Chinese media classed the satellite as a new remote sensing bird that will be used for “scientific experiments, land survey, crop yield assessment, and disaster monitoring.”
Also on board the launch vehicle was the small TX-1 Tian Xun-1 satellite, which is equipped with a 2.5 kg CCD camera that was built by Suzhou University, sporting a maximum resolution of 30 meters. The satellite is 0.60 m x 0.75 cm in size, with a weight of 35 kg.
As was the case for the other launches of the YaoGan Weixing series, Western analysts believe this class of satellites is being used for military purposes. The previous satellite in the series, YaoGan Weixing-11, was launched September 22, 2010 from the Jiuquan Satellite Launch Center by a CZ-2D Chang Zheng-2D.
Looking back to the YaoGan Weixing launch series we can calculate the potential purpose of this new new electro-optical observation spacecraft.
The first YaoGan Weixing satellite (29092 2006-015A) was launched by a CZ-4C Chang Zheng-4C (Y1) from the Taiyuan Satellite Launch Center on April 27, 2006. Developed by Shanghai Academy of Spaceflight Technology (SAST), the details about this satellite were closely guarded, but later it was said that this was the first Jian Bing-5 satellite, equipped with the first space-based synthetic aperture radar (SAR).
The second satellite on the series, the YaoGan Weixing-2 (31490 2007-019A), was launched on 25 May, 2007, by a CZ-2D Chang Zheng-2D (Y8) from the Jiuquan Satellite Launch Center. Details were also restricted, though it is claimed that this spacecraft is an electro-optical military observation satellite, complementing the results of the YaoGan Weixing-1. This satellite was developed by the China Academy of Space Technology (CAST).
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Another SAR mission was launched on November 11, 2007 with the YaoGan Weixing-3 (32289 2007-055A) satellite orbited by a CZ-4C Chang Zheng-4C (Y3) launch vehicle from Taiyuan. Other SAR missions were the YaoGan Weixing-6 (34839 2009-021A), launched by a CZ-2C Chang Zheng-2C-III (Y19) from Taiyuan on April 22, 2009, and the YaoGan Weixing-8 (36121 2009-072A), launched on December 15, 2009, by the CZ-4C (Y4) also from Taiyuan.
On December 1, 2008, YaoGan Weixing-4 (33446 2008-061A) – the second electro-optical satellite on the series – was launched by a CZ-2D Chang Zheng-2D (Y9) from Jiuquan, and on December 15, 2008, YaoGan Weixing-5 (33456 2008-064A) was launched by a CZ-4B Chang Zheng-4B (Y20) from Taiyuan. It is now believed that this satellite was the fourth electro-optical bird on the series, as well as the YaoGan Wexing-7 (36110 2009-069A) launch on December 9th, 2009 from Jiuquan by a Chang Zheng-2D (Y10).
The YaoGan Weixing-9 mission, launched March 5th 2010 from Jiuquan, had an architecture different from the previous missions on the series. Launched by CZ-4C Chang Zheng-4C (Y5) rocket, the mission put not one but a triplet of satellites in Earth orbit. Flying in formation this three satellites form what looks like a type of NOSS system.
So, looking back at the launch sequence on the series and taking into account that this launch took place from Taiyuan and used a CZ-4B Chang Zheng-4B launch vehicle, is possible that YG-12 YaoGan Weixing-12 is a new electro-optical observation satellite developed by CAST.
This was the 145th successful Chinese orbital launch, the 144th launch of a Chang Zheng launch vehicle, the 33rd successful orbital launch from Taiyuan (the 1st in 2011) and the 8th orbital Chinese launch in 2011.
The CZ-4B Chang Zheng-4B launch vehicle:
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. Initially, the Chang Zheng-4 served as a back-up 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. In other hand The CZ-4B 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 CZ-4 Chang Zheng-4.
The rocket is capable of launching a 2,800 kg satellite into low Earth orbit, developing 2,960,000 kN at launch. With a mass of 249,000 kg, the CZ-4B is 45.80 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 introduce on the CZ-4B Chang Zheng-4B included a larger satellite fairing and the replacement of the original mechanical-electrical control on the Chang Zheng-4 with an electronic control.
Other modifications were an improved telemetry, tracking, control, and self-destruction systems with smaller size and lighter weight; a revised nuzzle 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 Chang Zheng-4B uses UDMH/N2O4 for all three stages. The first stage uses a YF-21B motor consisting of four 75,000kg thrust YF-20B thrust chambers motors with swinging nozzles. The second stage is similar to that of the CZ-3A, with a YF-24F rocket motor consisting of one 75,000kg thrust YF-22B main motor with fixed nozzles, and a YF-23F swivelling venire motor with four chambers motors (4,700kg thrust in total).
The third stage is a specially designed unit powered by a 98kN YF-40 rocket motor.
The Taiyuan Satellite Launch Center:
Situated in the Kelan County on 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 center is based at a location 1400-1900m above sea level, and is surrounded by mountains to the east, south and north, with the Yellow River to its west. The annual average temperature is 4-10 degrees C, with maximum of 28 degrees C in summer and minimum of -39 degrees C in winter.
TSLC is suitable for launching a range of satellites, especially for low earth and sun-synchronous orbit missions. The center has state-of-the-art facilities for launch vehicle and spacecraft testing, preparation, launch and in-flight tracking and safety control, as well as for orbit predictions.