Long March 2D lofts latest Yaogan Weixing satellite

The Chinese have launched the Yaogan Weixing-31 remote sensing satellite via a Long March-2D (Chang Zheng-2D) on Sunday. The launch – from the Jiuquan Satellite Launch Center (JSLC) – took place at 04:10 UTC from the 603 Launch Platform at the LC43 Launch Complex.

Yaogan-31 Launch:

As per usual for the Chinese media, this spacecraft is once again classed 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 previous launches of the Yaogan Weixing series, analysts believe this class of satellites is used for military purposes.

A Y-W SatelliteAs was the case with the former Soviet Union (and in a smaller scale with Russia) with the ‘Cosmos’ designation, the ‘Yaogan’ designation is used to hide the true military nature of the vehicles orbited.

Yaogan-31 is probably an electro-optical observation satellite based on the military Jianbing-6 series or in follow-on series to Jianbing-6.

Similar satellites were the Yaogan-2 (31490 2007-019A) that was launched on 25 May, 2007; the Yaogan-4 (33446 2008-061A) launched on December 1, 2008; the Yaogan-7 (36110 2009-069A), launched on December 9, 2009; the Yaogan-11 (37165 2010-047A) launched on September 22, 2010.

It is possible that the Yaogan-24 launched on November 20, 2014 (40310 2014-072A) and the Yaogan-30 launched on May 15, 2016 (41473 2016-029A) are also Jianbing-6 satellites or the first two elements of a follow-on series.

All the satellites were launched by Long March-2D rockets from the Jiuquan Satellite Launch Center.

The Jianbing-6 electro-optical satellites carry high resolution optical sensors and reportedly have a resolution of between one to three meters and are placed in orbits that provide favorable illumination for the imaging missions.

Launch vehicle and launch site:

The Long March-2D (LM-2D) launch vehicle is a two-stage rocket developed by the Shanghai Academy of Spaceflight Technology. With storable propellants is mainly used to launch a variety of low earth orbit satellites.

The development of LM-2D was started in February 1990. From 2002, to meet the demand of SSO satellites, the payload fairing of 3350mm in diameter and attitude control engine for the second stage have been successfully developed; and the discharge of remaining propellant and de-orbit of the second stage have been realized. This launcher is mainly used for launching LEO and SSO satellites. It is characterized by high reliability, wide application and mature technology.

The LM-2D can launch a 1,300 kg cargo in a 645 km SSO. The rocket is 41.056 meters long and the first, second stages and payload fairing are all 3.35 meters in diameter.

Its first stage is the same of the Long March-4. The second stage is based on LM-4 second stage with an improved equipment bay. Lift-off mass is 232,250 kg, total length 41,056 meters, diameter 3.35 meters and fairing length 6.983 meters. At launch, it develops 2961.6 kN engine thrust.

The first stage has a 27.910 meter length with a 3.35 meter diameter, consuming 183,200 kg of N2O4 / UDMH (launch mass of the first stage is 192,700 kg). Equipped with a YF-21C engine capable of a ground thrust of 2,961.6 kN and a ground specific impulse of 2,550 m/s. Burn time is 170 seconds.

The second stage has a 10.9 meter length with a 3.35 meter diameter, launch mass of 39,550 kg and consuming 45,550 kg of N2O4 / UDMH. Equipped with a YF-24C cluster engine with a main engine vacuum thrust of 742.04 kN and a vernier engine with a vacuum thrust of 47.1 kN (specific impulses of 2,942 m/s and 2,834 m/s, respectively).

The LM-2D can use two types of fairings depending on the cargo. Type A fairing has a 2.90 meters diameter (total launch vehicle length is 37.728 meters) and Type B fairing with a diameter of 3.35 meters – total launch vehicle length is 41.056 meters.

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The first launch of the LM-2D was on August 9th, 1992 from the Jiuquan Satellite Launch Center orbiting the Fanhui Shei Weixing FSW-2-1 (22072 1992-051A) recoverable satellite.

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.

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 by South Launch Site (SLS) is equipped with two launch pads: 921 and 603. Launch pad 921 is used for the manned program for the launch of the Long March-2F launch vehicle (Shenzhou and Tiangong). The 603 launch pad 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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