Long March 4C launches three Yaogan Weixing-17 satellites

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Another super-secretive launch took place on Sunday from the Jiuquan Satellite Launch Center as China orbited three satellites under the Yaogan Weixing-17 mission. Launch took place at 19:16 UTC from the 603 launch pad of the LC43 launch complex using a Long March-4C (Chang Zheng-4C) launch vehicle.


Chinese Launch:

This is the Yaogan Weixing-17 mission composed of three satellites. Chinese media refer the new satellite as a new remote sensing bird that will be used for scientific experiments, land survey, crop yield assessment, and disaster monitoring.

As was the case in the last launches of the Yaogan Weixing series, western analysts believe this class of satellites is being used for military purposes.

In particular this mission is similar to the Yaogan Weixing-9 and Yaogan Weixing-16, with three satellites flying in formation like a type of NOSS system.

Designed for locating and tracking foreign warships the satellites will collect the optical and radio electronic signatures of the maritime vessels that will be used in conjunction with other information valuable for the Chinese maritime forces.

Yaogan-9 was launched on March 5, 2010 and Yaogan-16 was launched on November 25, 2012.

This was the 180th successful Chinese orbital launch, all of which have used the Chang Zheng launch vehicle. It was also the 60th successful orbital launch from Jiuquan – the fourth from Jiuquan this year – becoming the sixth successful orbital Chinese launch in 2013.

Looking back to the Yaogan Weixing launch series:

The first Yaogan Weixing satellite (29092 2006-015A) was launched by a 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 Jianbing-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 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 also known as JB-6 Jianbing-6, complementing the results of the Yaogan Weixing-1.

Another SAR mission similar to Yaogan-1 was launched on November 11, 2007 – with the Yaogan Weixing-3 (32289 2007-055A) satellite orbited by a Chang Zheng-4C (Y3) launch vehicle from Taiyuan.

A Y-W SatelliteYaogan Weixing-4 (33446 2008-061A) was then launched on December 1, 2008. This was the second electro-optical satellite on the series and was launched by a Chang Zheng-2D (Y9) from Jiuquan.

Other satellite in the Jianbing-6 series were Yaogan Wexing-7 (36110 2009-069A), launched on December 9, 2009 from Jiuquan by a Chang Zheng-2D (Y10), and Yaogan Weixing-11 (37165 2010-047A) launched on September 22, 2010, by the Chang Zheng-2D (Y11) launch vehicle from Jiuquan.

The first second-generation electro-optical reconnaissance satellite developed by CAST, Yaogan Weixing-5 (33456 2008-064A), was launched on December 15, 2008. The launch took place from Taiyuan by the Chang Zheng-4B (Y20) rocket.

Yaogan Weixing-12 (37875 2011-066B) was other second-generation electro-optical reconnaissance satellite, launched on November 11, 2011, by the Chang Zheng-4B (Y21) launch vehicle from Taiyuan.

Yaogan Weixing-6 (34839 2009-021A), launched by a Chang Zheng-2C-III (Y19) from Taiyuan on April 22, 2009, was a second-generation SAR satellite developed by SAST, having a spatial resolution of 1.5m.

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Other second-generation SAR satellites were the Yaogan Weixing-10 (36834 2010-038A) launch on August 9, 2010, by the Chang Zheng-4C (Y6) launch vehicle from Taiyuan; and the Yaogan Weixing-13 (37941 2011-072A) launch on November 29, 2011, by the Chang Zheng-2C (Y20) launch vehicle from Taiyuan.

The Yaogan Weixing-8 (36121 2009-072A), launched on December 15, 2009, by the CZ-4C (Y4) from Taiyuan was a new generation of optical reconnaissance satellite. Similar to the Yaogan-8 was the mission of Yaogan Weixing-14 launched on May 10th, 2012 by the Chang Zheng-4B (Y12) from Taiyuan.

The YaoGan Weixing-9 mission, launched March 5, 2010 from Jiuquan, had an architecture different from the previous missions on the series. Launched by 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.

The Yaogan Wrinxing-15 was a optical reconnaissance satellite launched on May 29, 2012 by the Chang Zheng-4C (Y10) from Taiyuan. The launch used a Long March 4C (Chang Zheng-4C) launch vehicle, an optimized version of the Long March 4B (Chang Zheng-4B), using an upper stae with restart capability and a new interstage adapter between the first and second stages. This vehicle also used a 3.35m diameter fairing for the Yaogan 15 ride uphill.

Launch Vehicle and Launch Site:

With its main commonality matched to the Long March 4B, 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 first stage is 193.330 kg).

Long March 4CThe 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.

It includes 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 vacuum of 2,971 Ns/kg.

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.

Launch SiteThe 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.

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.

Presently, only the LC-43 launch complex, also known by South Launch Site (SLS) is in use. This launch complex is equipped with two launch pads: 921 and 603. Launch pad 921 is used for the manned program for the launch of the Chang Zheng-2F launch vehicle (Shenzhou and Tiangong). The 603 launch pad is used for unmanned orbital launches by the Chang Zheng-2C, Chang Zheng-2D and Chang Zheng-4C launch vehicles.

The first orbital launch took place on April 24, 1970 when the CZ-1 Chang Zheng-1 (CZ1-1) rocket launched the first Chinese satellite, the Dongfanghong-1 (04382 1970-034A).

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