Long March 4C lofts Yaogan Weixing-25 mission

by Rui C. Barbosa

The Chinese successfully launched the Yaogan Weixing-25 mission – consisting of three satellites – from the Jiuquan Satellite Launch Center on Wednesday. The launch took place from the 603 launch pad of the LC43 launch complex utilizing a Long March-4C (Chang Zheng-4C) launch vehicle.

Chinese Launch:

The Yaogan Weixing-25 mission is composed of three satellites, with Chinese media referring to the new satellite as “a new remote sensing bird that will be used for scientific experiments, land survey, crop yield assessment, and disaster monitoring.”

The designation of the Yaogan Weixing series is used to hide the true military nature of the satellites.

In particular this mission is similar to the Yaogan-9, Yaogan-16, Yaogan-17 and Yaogan-20, with three satellites flying in formation like a type of NOSS system, considered as the Jianbing-8 military series.

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, while Yaogan-16 was launched on November 25, 2012; Yaogan-17 was launched on September 1st, 2013, and Yaogan-20 launched on August 9, 2014.

This launch was the 202nd Chinese orbital launch and the 201st launch of the Long March launch vehicle family. It was also the 71st successful orbital launch from the Jiuquan Satellite launch Center, the 8th launch from Jiuquan this year and the 14th launch in 2014.

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).

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.

£¨Ð»ªÖ±»÷£©£¨2£©ÎÒ¹ú¡°Ò»¼ýÈýÐÇ¡±³É¹¦·¢Éä3¿Å¼¼Êõ¿ÆѧÊÔÑéÎÀÐÇIt 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.

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.2014-09-28 10_08_40-Shi Jian 11-07, CZ-2C, JSLC - 05_28UTC, September 28, 2014Jiuquan 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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