China is preparing for the launch of one of the heaviest ever satellites to geostationary orbit next month, with the country's second Long March 5 heavy-lift launch vehicle being assembled at the Wenchang Satellite Launch Centre.

Shijian-18 is an experimental telecommunications satellite which, at around seven metric tonnes or more launch mass, will possibly be the most massive satellite launched to geostationary orbit, nearly 36,000 km above the Earth.

It will be the first deployment of the new Dongfanghong-5 (DFH-5) satellite platform, the country's most advanced and heaviest, which requires the new Long March 5 to send it into geosynchronous transfer orbit.

Shijian-13, launched last month, was China's first high-throughput satellite with a capacity of more than 20 Gbps, and marked the country's first full use of electric propulsion with LIPS-200 engines, developed by the Lanzhou Institute of Physics.

Shijian-18 will immediately overshadow those capabilities, boasting a capacity of around 70 Gbps, while also feature more powerful LIPS-300 ion thrusters.

Like SJ-13, the Ka band SJ-18 telecommunications satellite will also test space-based laser communications.
 

The DFH-5 was developed by the China Academy of Space Technology (CAST) under the China Aerospace Science and Technology Corporation (CASC), the main contractor for the Chinese space programme.

While official figures have not been released, DFH-5 could have a mass of between 6,500 - 9,000 kg, with a payload greater than 1500 kg.

Above: Apparent DFH-5 design capabilities (CAST).

The components of the Long March 5 (Y2) were delivered to the island province of Hainan in late April by specially designed cargo ships Yuanwang-21 and 22.

Boosting China's launch capabilities

The first Long March 5 was launched in dramatic circumstances in November last year, carrying the Shijian-17 (Shijian means 'practice') satellite to geosynchronous transfer orbit.

The third flight of Long March 5 is expected in late November to launch Chang'e-5, a complex and ambitious mission to collect samples from the lunar surface and return to Earth.

The Chang'e-5 return capsule (right) and lander and ascent vehicles (left, background) (Framegrab/CCTV).

At over 50m high and with a diameter of 5m, the Long March 5 will have a mass at liftoff of close to 800 metric tonnes and its development greatly boosted China's space capabilities.

Background: Five things to know about China's Long March 5

The Long March 5B variant is capable of putting a 25 metric tonne payload into low Earth orbit and will be used to launch the 20mt core module of the Chinese Space Station, Tianhe, sometime around early 2019.

Above: The maiden flight of Long March 5 in November 2016.

China's space programme in 2017

Shijian-18 is likely to be China's sixth orbital launch of 2017, following Shijian-13, TJS-2, a Kuaizhou-1A rocket launch, Tiankun-1, and China's first orbital cargo vessel, Tianzhou-1.

However, a potentially busy June launch schedule and the opaque nature of China's space activities means that other missions expected in June could proceed it. 

The Hard X-ray Modulation Telescope (HXMT) space science mission is set to launch from Jiuquan in the Gobi Desert on a Long March 4B, while a Long March 3B is expected to loft Zhongxing-9A telecomms satellite to geostationary orbit from Xichang.

The China Aerospace Science and Technology Corporation (CASC), the main contractor for the Chinese space programme and of which CAST is a subsidiary, is aiming for close to 30 launches in 2017, with further solid-fuelled rocket launches of small satellites also expected for another state-run space actor, CASIC.

Quelle: gbtimes