Xinhua Insight: A look into China's latest space center

On the northeast coast of China's biggest tropical island, the country's fourth satellite launch center is preparing for lift off. If the small city of Wenchang was previously known to the world at all, it was for coconuts and a signature chicken dish. It is from here that, all being well, China's new generation Long March-7 carrier rocket will begin its first mission in the next few days.

The launch is scheduled for between Saturday and Wednesday. All of the city's hotel rooms -- enough for 80,000 people -- are booked out and there are eight viewing areas for space fans to observe the spectacle.

It took five years to build the center which was completed in November 2014 and covers an area of 20 square km, featuring two launch pads and a science theme park catering to young space science enthusiasts. The operational part of the site is divided into three areas: transfer, test, and launch. Coconut groves, wetlands and ponds are scattered here and there.

The 53-meter, 597-tonne rocket was moved to the launch pad on Wednesday morning from its assembly and testing building.

The two launch pads, around 600 meters from the beach, have 92 meter and 86 meter gantries, one for the new Long March-7 and and the other for the heavy-lift Long March-5 with its payload capacity of 25 tonnes to low Earth orbit, or 14 tonnes to geostationary transfer orbit.

Over 80 control and test rooms provide all-around technical support. Under each launch pad is a diversion ditch, which allows the huge amount of heat generated during the launch to dissipate.

Apart from the launch pads, the most outstanding structures in the center are the assembly and testing buildings. Standing 3.5 km from the sea, the two have one thing in common: immensity.

The taller one, 99 meters high, accommodates the heavy-lift Long March-5. It has 14 floors above ground and one underground. Its steel door, 81 meters high, is Asia's largest. The home of the medium-lift Long March-7, is slightly smaller but still impressive.

China's fourth launch site, Wenchang will be used to dispatch satellites, large space stations and deep-space probes. It is designed to handle up to 10-12 launches a year. The planned space station and all attendant cargo and service launches will be handled by Wenchang.

China's three other launch bases -- Jiuquan, Xichang and Taiyuan -- are located in sparsely-populated inland areas. Wenchang was specially selected for its low latitude: only 19 degrees north of the equator.

The lower the latitude, the larger the centrifugal force and consequently the lower the launch cost. As long ago as 2007, Chinese Academy of Engineering carrier rocket expert Long Lehao declared that, "Hainan is close to the equator, so much energy could be saved if a satellite base was built there."

Satellites launched from low latitudes are expected to have a longer service life as a result of the fuel saved by a shorter maneuver from transit to geosynchronous orbit. That extra fuel can later be used to regulate and sustain orbit.

Wenchang's latitudinal advantages will allow the payload to be increased by more than 300 kg, 7.4 percent more than from any of the other three centers. That translates into a saving of 6 million U.S. dollars each launch. The current world price for rocket payload is about 20,000 U.S. dollars per kg.

Another benefit of the coastal center is that rockets will pass over open sea for up to 1,000 km, which avoids the danger of burning wreckage falling on residential areas.

Moreover, coastal Wenchang can receive deliveries of modules of large spacecraft by sea, while the other launch centers are all landlocked in remote plateau and mountainous regions that can only be reached by rail.

The rocket now waiting on the launch pad was taken to Wenchang on May 16 from north China's port city of Tianjin. The 1,670-nautical-mile trip took eight days.

The tropical weather, however, is a source of concern. Not every day is a sunny one in low-altitude coastal areas, with typhoons and thunderstorms constant threats. Wenchang's designers have used new technology to protect the launch ground against the ravages of wind and rain.

Unlike the steel structure of the launch pad at the Jiuquan center, the structure in Wenchang is made of both steel and reinforced concrete. Since 2009 when construction began, the center has withstood eight typhoons, including Rammasun in 2014, the strongest in 41 years.

Wenchang sees more than 100 days of thunderstorms each year. To deal with this threat, four 105-meter steel lightning conductors surround each launch pad, effective against 98.6 percent of thunderstorm, much higher than the 90 percent in other domestic launch centers.

A special anti-corrosion dope is used on metal surfaces to protect against Wenchang's moist, salty environment.

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Space Center China