Surprise Chinese launch of the Yaogan Weixing-31-01 mission

by Rui C. Barbosa

Aiming for a record-breaking year, the Chinese have successfully launched the Yaogan Weixing-31-01 mission – consisting of three satellites – from the Jiuquan Satellite Launch Center at 04:25 UTC on Tuesday morning. The surprise launch also carried another small – if unnamed – satellite. The launch took place from Launch Pad 94 of the LC43 launch complex using the Long March 4C (Y25) rocket.

The Yaogan Weixing-31-01 mission is composed of three satellites, with Chinese media referring to the new satellites to be used “for electromagnetic environment surveys and other related technology tests.”

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, 16, 17, 20 and 31 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.

Chinese TV video of a previous launch of this satellite range

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, Yaogan-20 launched on August 9, 2014, and Yaogan-25 was launched on December 10, 2014.

Together with the three Yaogan-30-01 satellites was launched a micro/nano technology test satellite. No specific designation was given to the small satellite.

This launch was the 271st launch of the Long March launch vehicle family and the 11th orbital this year.

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.

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 Long March 4C launches the three satellites – via Chinese social media

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.

The Jiuquan Satellite Launch Center

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).

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